Patent Application
20210292907
The present invention relates to sealing compositions and methods for treating a metal substrate. The present invention also relates to a coated metal substrate.
The use of protective coatings on metal substrates for improved corrosion resistance and paint adhesion is common. Conventional techniques for coating such substrates include techniques that involve pretreating the metal substrate with chromium-containing compositions. The use of such chromate-containing compositions, however, imparts environmental and health concerns.
As a result, chromate-free pretreatment compositions have been developed. Such compositions are generally based on chemical mixtures that react with the substrate surface and bind to it to form a protective layer. For example, pretreatment compositions based on a Group IIIB metal or Group IVB metal have become more prevalent. Such compositions often contain a source of free fluoride, i.e., fluoride available as isolated ions in the pretreatment composition as opposed to fluoride that is covalently or ionically bound to another element cation, such as the Group TIM or a Group IVB metal ion or hydrogen ion. Free fluoride can etch the surface of the metal substrate, thereby promoting deposition of a Group TIM or Group IVB metal coating. Nevertheless, the corrosion resistance capability of these pretreatment compositions has generally been significantly inferior to conventional chromium-containing pretreatments.
It would be desirable to provide compositions and methods for treating a metal substrate that overcome at least some of the previously described drawbacks of the prior art, including the environmental drawbacks associated with the use of chromates. It also would be desirable to provide compositions and methods for treating metal substrate that impart corrosion resistance properties that are equivalent to, or even superior to, the corrosion resistance properties imparted through the use of phosphate- or chromium-containing conversion coatings. It would also be desirable to provide related coated metal substrates.
Disclosed herein is a system for treating a substrate comprising: a first composition for contacting at least a portion of the substrate, the first composition comprising a lanthanide series element cation and an oxidizing agent.
Also disclosed herein is a method of treating a substrate comprising: contacting at least a portion of the substrate with a first composition comprising a lanthanide series element cation and an oxidizing agent.
Also disclosed are substrates obtainable by the system and/or methods.
As mentioned above, disclosed herein is a system comprising, or in some cases, consisting essentially of, or in some cases, consisting of, a first composition comprising, or in some cases, consisting essentially of, or in some cases, consisting of, a lanthanide series element cation and an oxidizing agent. The system may further comprise, or in some cases, consist essentially of, or in some cases, consist of, a second composition comprising, or in some cases, consisting essentially of, or in some cases, consisting of, a Group IA metal cation, or a third composition comprising, or in some cases, consisting essentially of, or in some cases, consisting of, a Grope IVB metal cation. The first, second, and third composition each may be a sealing composition or a conversion composition, as defined herein.
According to the method of the present invention, at least a portion of the substrate may be contacted with the first composition, and may optionally be contacted with the second composition or the third composition. According to the invention, the contacting with the first composition may precede or follow the contacting with the second and/or third composition. As described more fully herein, there may, in some instances, there may be rinse steps that intervene the contacting with the first composition and the second and/or third composition.
The present invention also is directed to a substrate comprising a film formed from a pretreatment composition comprising a lanthanide series element source and an oxidizing agent, wherein the level of the lanthanide series element in the film is at least 100 counts greater than on a surface of a substrate that does not have the film thereon as measured by X-ray fluorescence (60 second timed assay, 15 Kv, 45 μA, filter 3, T(p)=1.5 μs).
The substrate may further comprise a film or a layer formed from the Group IA metal cation or the Group IVB metal cation.
Suitable substrates that may be used in the present invention include metal substrates, metal alloy substrates, and/or substrates that have been metallized, such as nickel plated plastic. According to the present invention, the metal or metal alloy can comprise or be steel, aluminum, zinc, nickel, and/or magnesium. For example, the steel substrate could be cold rolled steel, hot rolled steel, electrogalvanized steel, and/or hot dipped galvanized steel. Aluminum alloys of the 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, or 7XXX series as well as clad aluminum alloys also may be used as the substrate. Aluminum alloys may comprise 0.01% by weight copper to 10% by weight copper. Aluminum alloys which are treated may also include castings, such as 1XX.X, 2XX.X, 3XX.X, 4XX.X, 5XX.X, 6XX.X, 7XX.X, 8XX.X, or 9XX.X (e.g.: A356.0). Magnesium alloys of the AZ31B, AZ91C, AM60B, or EV31A series also may be used as the substrate. The substrate used in the present invention may also comprise titanium and/or titanium alloys, zinc and/or zinc alloys, and/or nickel and/or nickel alloys. According to the present invention, the substrate may comprise a portion of a vehicle such as a vehicular body (e.g., without limitation, door, body panel, trunk deck lid, roof panel, hood, roof and/or stringers, rivets, landing gear components, and/or skins used on an aircraft) and/or a vehicular frame. As used herein, “vehicle” or variations thereof includes, but is not limited to, civilian, commercial and military aircraft, and/or land vehicles such as cars, motorcycles, and/or trucks.
According to the present invention, the first composition may comprise a lanthanide series element cation. The first composition also may further comprise an ion of a Group IIA metal, a Group VB metal, a Group VIB metal, a Group VIIB metal, and/or a Group XII metal (together with the lanthanide series cation, the Group TIM metal cation, and/or the Group IVB metal cation, referred to collectively herein as “first composition metal cations”).
According to the present invention, the lanthanide series metal cation may be present in the first composition in an amount of at least 5 ppm, such as at least 150 ppm, such as at least 300 ppm, (calculated as metal cation) based on total weight of the first composition, and in some instances may be present in the first composition in an amount of no more than 25,000 ppm, such as no more than 12,500 ppm, such as no more than 10,000 ppm, (calculated as metal cation) based on total weight of the first composition. According to the present invention, lanthanide series metal cation may be present in the first composition in an amount of 5 ppm to 25,000 ppm, such as 150 ppm to 12,500 ppm, such as 300 ppm to 10,000 ppm, (calculated as metal cation) based on total weight of the first composition.
According to the present invention, the lanthanide series element cation may, for example, comprise cerium, praseodymium, terbium, or combinations thereof; the Group IIA metal cation may comprise magnesium; the Group IIIB metal cation may comprise yttrium, scandium, or combinations thereof; the Group IVB metal cation may comprise zirconium, titanium, hafnium, or combinations thereof; the Group VB metal cation may comprise vanadium; the Group VIB metal may comprise molybdenum; the Group VIIB metal cation may comprise trivalent or hexavalent chromium or manganese; and the Group XII metal cation may comprise zinc (collectively, the “conversion composition metal cations”).
According to the present invention, the first composition may further comprise an anion that may be suitable for forming a salt with the first composition metal cations, such as a halogen, a nitrate, a sulfate, a phosphate, a silicate (orthosilicates and metasilicates), carbonates, hydroxides, and the like. According to the present invention, the first composition metal salt may be present in the first composition in an amount of at least 50 ppm (calculated as metal salt) based on total weight of the first composition, such as at least 1000 ppm, and in some instances, may be present in an amount of no more than 30,000 ppm, such as no more than 2000 ppm. According to the present invention, the first composition metal salt may be present in an amount of 50 ppm to 30,000 ppm, such as 1000 ppm to 2000 ppm (calculated as metal salt) based on total weight of the first composition.
According to the present invention, the halogen may be present in the first composition, if at all, in an amount of at least 5 ppm (calculated as anion) based on total weight of the first composition, such as at least 50 ppm, such as at least 150 ppm, such as at least 500 ppm, and may be present in an amount of no more than 25,000 ppm (calculated as anion) based on total weight of the first composition, such as no more than 18,500 ppm, such as no more than 4000 ppm, such as no more than 2000 ppm. According to the present invention, the halogen may be present in the first composition, if at all, in an amount of 5 ppm to 25,000 ppm (calculated as anion) based on total weight of the first composition, such as 50 ppm to 18,500 ppm, such as 150 ppm to 4000, such as 500 ppm to 2000 ppm.
According to the present invention, the nitrate may be present in the first composition, if at all, in an amount of at least 2 ppm (calculated as anion) based on total weight of the first composition, such as at least 50 ppm, such as at least 250 ppm, and may be present in an amount of no more than 10,000 ppm (calculated as anion) based on total weight of the first composition, such as no more than 5000 ppm, such as no more than 2500 ppm. According to the present invention, the halogen may be present in the first composition, if at all, in an amount of 2 ppm to 10,000 ppm (calculated as anion) based on total weight of the first composition, such as 50 ppm to 5000 ppm, such as 250 ppm to 2500 ppm.
According to the present invention, the first composition metal cation may be present in the first composition in an amount of at least 5 ppm, such as at least 150 ppm, such as at least 300 ppm, (calculated as metal cation) based on total weight of the first composition, and in some instances may be present in the first composition in an amount of no more than 25,000 ppm, such as no more than 12,500 ppm, such as no more than 10,000 ppm, (calculated as metal cation) based on total weight of the first composition. According to the present invention, the first composition metal cation may be present in the first composition in an amount of 5 ppm to 25,000 ppm, such as 150 ppm to 12,500 ppm, such as 300 ppm to 10,000 ppm (calculated as metal cation) based on total weight of the first composition.
According to the present invention, the first composition may comprise an oxidizing agent. Non-limiting examples of the oxidizing agent include peroxides, persulfates, perchlorates, hypochlorite, nitric acid, sparged oxygen, bromates, peroxi-benzoates, ozone, or combinations thereof.
According to the present invention, the oxidizing agent may be present in an amount of at least 100 ppm, such as at least 500 ppm, based on total weight of the first composition, and in some instances, may be present in an amount of no more than 13,000 ppm, such as no more than 3000 ppm, based on total weight of the first composition. In some instances, the oxidizing agent may be present in the first composition in an amount of 100 ppm to 13,000 ppm, such as 500 ppm to 3000 ppm, based on total weight of the first composition.
According to the present invention, the first composition may exclude chromium or chromium-containing compounds. As used herein, the term “chromium-containing compound” refers to materials that include hexavalent chromium. Non-limiting examples of such materials include chromic acid, chromium trioxide, chromic acid anhydride, dichromate salts, such as ammonium dichromate, sodium dichromate, potassium dichromate, and calcium, barium, magnesium, zinc, cadmium, and strontium dichromate. When a composition and/or a coating or a layer, respectively, formed from the same is substantially free, essentially free, or completely free of chromium, this includes chromium in any form, such as, but not limited to, the hexavalent chromium-containing compounds listed above.
Thus, optionally, according to the present invention, the first compositions and/or coatings or layers, respectively, deposited from the same may be substantially free, may be essentially free, and/or may be completely free of one or more of any of the elements or compounds listed in the preceding paragraph. A first composition and/or coating or layer, respectively, formed from the same that is substantially free of chromium or derivatives thereof means that chromium or derivatives thereof are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the conversion composition; in the case of chromium, this may further include that the element or compounds thereof are not present in the first compositions and/or coatings or layers, respectively, formed from the same in such a level that it causes a burden on the environment. The term “substantially free” means that the compositions and/or coating or layers, respectively, formed from the same contain less than 10 ppm of any or all of the elements or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the conversion compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppm of any or all of the elements or compounds listed in the preceding paragraph, if any at all. The term “completely free” means that the compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppb of any or all of the elements or compounds listed in the preceding paragraph, if any at all.
According to the present invention, the first composition may, in some instances, exclude phosphate ions or phosphate-containing compounds and/or the formation of sludge, such as aluminum phosphate, iron phosphate, and/or zinc phosphate, formed in the case of using a treating agent based on zinc phosphate. As used herein, “phosphate-containing compounds” include compounds containing the element phosphorous such as ortho phosphate, pyrophosphate, metaphosphate, tripolyphosphate, organophosphonates, and the like, and can include, but are not limited to, monovalent, divalent, or trivalent cations such as: sodium, potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. When a composition and/or a layer or coating comprising the same is substantially free, essentially free, or completely free of phosphate, this includes phosphate ions or compounds containing phosphate in any form.
Thus, according to the present invention, composition and/or layers deposited from the same may be substantially free, or in some cases may be essentially free, or in some cases may be completely free, of one or more of any of the ions or compounds listed in the preceding paragraph. A composition and/or layers deposited from the same that is substantially free of phosphate means that phosphate ions or compounds containing phosphate are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the composition; this may further include that phosphate is not present in the conversion compositions and/or layers deposited from the same in such a level that they cause a burden on the environment. The term “substantially free” means that the compositions and/or layers deposited from the same contain less than 5 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the conversion compositions and/or layers comprising the same contain less than 1 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph. The term “completely free” means that the compositions and/or layers comprising the same contain less than 1 ppb of any or all of the phosphate anions or compounds listed in the preceding paragraph, if any at all.
Optionally, according to the present invention, the first composition may contain no more than one lanthanide series element and/or no more than one lanthanide series element source, such that the first composition may contain one lanthanide series element and/or a single lanthanide series element source, and in some instances, may be substantially free, or in some instances, essentially free, or in some instances, completely free, of more than one lanthanide series element and/or more than one lanthanide series element source.
In some instances, the first composition according to the present invention may be substantially free, or, in some cases, completely free of gelatin, such as, but not limited to, bovine, porcine, or fish.
In some instances, the first composition according to the present invention may be substantially free, or, in some cases, completely free of oxides. As used herein, the term “substantially free,” when used with respect to oxides in the first composition, means that oxides are not purposefully added to the first composition, and, if present at all, only is present in the pretreatment composition in a trace amount of 5 ppm or less, based on a total weight of the composition. As used herein, the term “essentially free,” when used with respect to oxides in the first composition, means that if oxide is present at all in the first composition, only is present in the pretreatment composition in an amount of 1 ppm or less, based on a total weight of the composition. As used herein, the term “completely free,” when used with respect to oxide in the first composition, means that oxide is present in the pretreatment composition in an amount of 1 ppb or less, based on a total weight of the composition.
According to the present invention, the pH of the first composition may be 1.0 to 4.5, such as 3 to 4, and may be adjusted using, for example, any acid and/or base as is necessary. According to the present invention, the pH of the first composition may be maintained through the inclusion of an acidic material, including water soluble and/or water dispersible acids, such as nitric acid, sulfuric acid, and/or phosphoric acid. According to the present invention, the pH of the composition may be maintained through the inclusion of a basic material, including water soluble and/or water dispersible bases, such as sodium hydroxide, sodium carbonate, potassium hydroxide, ammonium hydroxide, ammonia, and/or amines such as triethylamine, methylethyl amine, or mixtures thereof.
The first composition may comprise an aqueous medium and may optionally contain other materials such as nonionic surfactants and auxiliaries conventionally used in the art of conversion compositions. In the aqueous medium, water dispersible organic solvents, for example, alcohols with up to about 8 carbon atoms such as methanol, isopropanol, and the like, may be present; or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol, or propylene glycol, and the like. When present, water dispersible organic solvents are typically used in amounts up to about ten percent by volume, based on the total volume of aqueous medium.
Other optional materials include surfactants that function as defoamers or substrate wetting agents. Anionic, cationic, amphoteric, and/or nonionic surfactants may be used. Defoaming surfactants may optionally be present at levels up to 1 weight percent, such as up to 0.1 percent by weight, and wetting agents are typically present at levels up to 2 percent, such as up to 0.5 percent by weight, based on the total weight of the first composition.
The first composition may comprise a carrier, often an aqueous medium, so that the composition is in the form of a solution or dispersion of the lanthanide and/or Group IIIB metal cation in the carrier. In these embodiments, the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the invention, the solution or dispersion when applied to the metal substrate is at a temperature ranging from 40° F. to 160° F., such as 60° F. to 110° F., such as 70° F. to 90° F. For example, the conversion process may be carried out at ambient or room temperature. The contact time is often from 1 second to 15 minutes, such as 4 minutes to 10 minutes, such as 5 seconds to 4 minutes.
According to the present invention, following the contacting with the first composition, the substrate optionally may be dried in place, e.g., air dried at room temperature or be dried with hot air, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as by drying the substrate in an oven at 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls. According to the present invention, the substrate surface may be partially, or in some instances, completely dried prior to any subsequent contact of the substrate surface with any water, solutions, compositions, or the like. As used herein with respect to a substrate surface, “completely dry” or “completely dried” means there is no moisture on the substrate surface visible to the human eye. According to the present invention, following the contacting with the first composition, the substrate (either wet or dried in place) optionally may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents in order to remove any residue and then optionally may be dried, for example air dried or dried with hot air as described in the preceding sentence. According to the present invention, such water rinses may be eliminated and the substrate (either wet or dried in place) may be contacted with subsequent treatment compositions.
Optionally, a substrate (wet or dried as described above) treated with the first composition (and optionally with second or third compositions or electrocaot, powder coat or liquid coatings described herein) may be heated in an oven or heater such as ones described above at a temperature of 100 C to 240 C, such as 110 C to 232 C. It has been surprisingly discovered that such substrates have a b* value of less than 3.09 (spectral component excluded, 25 mm aperture).
According to the present invention, the second composition may comprise a Group IA metal cation, such as a lithium cation, which may be in the form of a salt. In addition, the second composition also may further comprise at least one Group IA metal cation other than lithium, a Group VB metal cation, and/or Group VIB metal cation. The at least one Group IA metal cation other than lithium, a Group VB metal cation, and/or Group VIB metal cation may be in the form of a salt. Nonlimiting examples of anions suitable for forming a salt with the lithium, Group IA cations other than lithium, Group VB cations, and/or Group VIB cations include carbonates, hydroxides, nitrates, halogens, sulfates, phosphates and silicates (e.g., orthosilicates and metasilicates) such that the metal salt may comprise a carbonate, an hydroxide, a nitrate, a halide, a sulfate, a phosphate, a silicate (e.g., orthosilicate or metasilicate), a permanganate, a chromate, a vanadate, a molybdate, and/or a perchlorate.
According to the present invention, the metal salts of the second composition (i.e., the salts of lithium, Group IA metals other than lithium, Group VB, and/or Group VIB) each may be present in the second composition in an amount of at least 25 ppm, such as at least 150 ppm, such as at least 500 ppm (calculated as total compound) based on total weight of the second composition, and in some instances, no more than 30000 ppm, such as no more than 2000 ppm, such as no more than 1500 ppm (calculated as total compound) based on total weight of the second composition. According to the present invention, the metal salts of the second composition (i.e., the salts of lithium, Group IA metals other than lithium, Group VB, and/or Group VIB) each may be present in the second composition in an amount of 25 ppm to 30000 ppm, such as 150 ppm to 2000 ppm, such as 500 ppm to 1500 (calculated as total compound) based on total weight of the second composition.
According to the present invention, the lithium cation, the Group IA cation other than lithium, the Group VB metal cation, and the Group VIB metal cation each may be present in the second composition in an amount of at least 5 ppm, such as at least 50 ppm, such as at least 150 ppm, such as at least 250 ppm (calculated as cation) based on total weight of the second composition, and in some instances, may be present in an amount of no more than 5500 ppm, such as no more than 1200 ppm, such as no more than 1000 ppm, such as no more than 500 ppm, (calculated as cation) based on total weight of the second composition. In some instances, according to the present invention, the lithium cation, the Group IA cation other than lithium, the Group VB metal cation, and the Group VIB metal cation each may be present in the second composition in an amount of 5 ppm to 5500 ppm, such as 50 ppm to 1000 ppm, (calculated as cation) based on total weight of the second composition, such as 150 ppm to 500 ppm.
According to the present invention, the lithium salt of the present invention may comprise an inorganic lithium salt, an organic lithium salt, or combinations thereof. According to the present invention, the anion and the cation of the lithium salt both may be soluble in water. According to the present invention, for example, the lithium salt may have a solubility constant in water at a temperature of 25° C. (K; 25° C.) of at least 1×10−11, such as least 1×10−11, and in some instances, may be no more than 5×10+2. According to the present invention, the lithium salt may have a solubility constant in water at a temperature of 25° C. (K; 25° C.) of 1×10−11 to 5×10+2, such as 1×10−4 to 5×10+2. As used herein, “solubility constant” means the product of the equilibrium concentrations of the ions in a saturated aqueous solution of the respective lithium salt. Each concentration is raised to the power of the respective coefficient of ion in the balanced equation. The solubility constants for various salts can be found in the Handbook of Chemistry and Physics.
According to the present invention, the second composition of the present invention may an include oxidizing agent, such as hydrogen peroxide, persulfates, perchlorates, sparged oxygen, bromates, peroxi-benzoates, ozone, and the like, or combinations thereof. For example, the second composition may comprise 0.1 wt % to 15 wt % of an oxidizing agent based on total weight of the second composition, such as 2 wt % to 10 wt %, such as 6 wt % to 8 wt %. Alternatively, according to the present invention, the second composition may be substantially free, or in some cases, essentially free, or in some cases, completely free, of an oxidizing agent.
According to the present invention, the second composition may exclude Group IIA metal cations or Group IIA metal-containing compounds, including but not limited to calcium. Non-limiting examples of such materials include Group IIA metal hydroxides, Group IIA metal nitrates, Group IIA metal halides, Group IIA metal sulfamates, Group IIA metal sulfates, Group IIA carbonates and/or Group IIA metal carboxylates. When a second composition and/or a coating or a layer, respectively, formed from the same is substantially free, essentially free, or completely free of a Group IIA metal cation, this includes Group IIA metal cations in any form, such as, but not limited to, the Group IIA metal-containing compounds listed above.
According to the present invention, the second composition may exclude chromium or chromium-containing compounds. As used herein, the term “chromium-containing compound” refers to materials that include hexavalent chromium. Non-limiting examples of such materials include chromic acid, chromium trioxide, chromic acid anhydride, dichromate salts, such as ammonium dichromate, sodium dichromate, potassium dichromate, and calcium, barium, magnesium, zinc, cadmium, and strontium dichromate. When a second composition and/or a coating or a layer, respectively, formed from the same is substantially free, essentially free, or completely free of chromium, this includes chromium in any form, such as, but not limited to, the hexavalent chromium-containing compounds listed above.
Thus, optionally, according to the present invention, the present second compositions and/or coatings or layers, respectively, deposited from the same may be substantially free, may be essentially free, and/or may be completely free of one or more of any of the elements or compounds listed in the preceding paragraph. A second composition and/or coating or layer, respectively, formed from the same that is substantially free of chromium or derivatives thereof means that chromium or derivatives thereof are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the second composition; in the case of chromium, this may further include that the element or compounds thereof are not present in the second compositions and/or coatings or layers, respectively, formed from the same in such a level that it causes a burden on the environment. The term “substantially free” means that the second compositions and/or coating or layers, respectively, formed from the same contain less than 10 ppm of any or all of the elements or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the second compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppm of any or all of the elements or compounds listed in the preceding paragraph, if any at all. The term “completely free” means that the second compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppb of any or all of the elements or compounds listed in the preceding paragraph, if any at all.
According to the present invention, the second composition may, in some instances, exclude phosphate ions or phosphate-containing compounds and/or the formation of sludge, such as aluminum phosphate, iron phosphate, and/or zinc phosphate, formed in the case of using a treating agent based on zinc phosphate. As used herein, “phosphate-containing compounds” include compounds containing the element phosphorous such as ortho phosphate, pyrophosphate, metaphosphate, tripolyphosphate, organophosphonates, and the like, and can include, but are not limited to, monovalent, divalent, or trivalent cations such as: sodium, potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. When a composition and/or a layer or coating comprising the same is substantially free, essentially free, or completely free of phosphate, this includes phosphate ions or compounds containing phosphate in any form.
Thus, according to the present invention, second composition and/or layers deposited from the same may be substantially free, or in some cases may be essentially free, or in some cases may be completely free, of one or more of any of the ions or compounds listed in the preceding paragraph. A second composition and/or layers deposited from the same that is substantially free of phosphate means that phosphate ions or compounds containing phosphate are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the composition; this may further include that phosphate is not present in the second compositions and/or layers deposited from the same in such a level that they cause a burden on the environment. The term “substantially free” means that the second compositions and/or layers deposited from the same contain less than 5 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the second compositions and/or layers comprising the same contain less than 1 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph. The term “completely free” means that the second compositions and/or layers comprising the same contain less than 1 ppb of any or all of the phosphate anions or compounds listed in the preceding paragraph, if any at all.
According to the present invention, the second composition may, in some instances, exclude fluoride or fluoride sources. As used herein, “fluoride sources” include monofluorides, bifluorides, fluoride complexes, and mixtures thereof known to generate fluoride ions. When a composition and/or a layer or coating comprising the same is substantially free, essentially free, or completely free of fluoride, this includes fluoride ions or fluoride sources in any form, but does not include unintentional fluoride that may be present in a bath as a result of, for example, carry-over from prior treatment baths in the processing line, municipal water sources (e.g.: fluoride added to water supplies to prevent tooth decay), fluoride from a pretreated substrate, or the like. That is, a bath that is substantially free, essentially free, or completely free of fluoride, may have unintentional fluoride that may be derived from these external sources, even though the composition used to make the bath prior to use on the processing line was substantially free, essentially free, or completely free of fluoride.
For example, the second composition may be substantially free of any fluoride-sources, such as ammonium and alkali metal fluorides, acid fluorides, fluoroboric, fluorosilicic, fluorotitanic, and fluorozirconic acids and their ammonium and alkali metal salts, and other inorganic fluorides, nonexclusive examples of which are: zinc fluoride, zinc aluminum fluoride, titanium fluoride, zirconium fluoride, nickel fluoride, ammonium fluoride, sodium fluoride, potassium fluoride, and hydrofluoric acid, as well as other similar materials known to those skilled in the art.
Fluoride present in the second composition that is not bound to metals ions such as Group IVB metal ions, or hydrogen ion, defined herein as “free fluoride,” may be measured as an operational parameter in the second composition bath using, for example, an Orion Dual Star Dual Channel Benchtop Meter equipped with a fluoride ion selective electrode (“ISE”) available from Thermoscientific, the Symphony® Fluoride Ion Selective Combination Electrode supplied by VWR International, or similar electrodes. See, e.g., Light and Cappuccino, Determination of fluoride in toothpaste using an ion-selective electrode, J. Chem. Educ., 52:4, 247-250, April 1975. The fluoride ISE may be standardized by immersing the electrode into solutions of known fluoride concentration and recording the reading in millivolts, and then plotting these millivolt readings in a logarithmic graph. The millivolt reading of an unknown sample can then be compared to this calibration graph and the concentration of fluoride determined. Alternatively, the fluoride ISE can be used with a meter that will perform the calibration calculations internally and thus, after calibration, the concentration of the unknown sample can be read directly.
Fluoride ion is a small negative ion with a high charge density, so in aqueous solution it is frequently complexed with metal ions having a high positive charge density, such as Group IVB metal ions, or with hydrogen ion. Fluoride anions in solution that are ionically or covalently bound to metal cations or hydrogen ion are defined herein as “bound fluoride.” The fluoride ions thus complexed are not measurable with the fluoride ISE unless the solution they are present in is mixed with an ionic strength adjustment buffer (e.g.: citrate anion or EDTA) that releases the fluoride ions from such complexes. At that point (all of) the fluoride ions are measurable by the fluoride ISE, and the measurement is known as “total fluoride”. Alternatively, the total fluoride can be calculated by comparing the weight of the fluoride supplied in the sealer composition by the total weight of the composition.
According to the present invention, the treatment composition may, in some instances, be substantially free, or in some instances, essentially free, or in some instances, completely free, of cobalt ions or cobalt-containing compounds. As used herein, “cobalt-containing compounds” include compounds, complexes or salts containing the element cobalt such as, for example, cobalt sulfate, cobalt nitrate, cobalt carbonate and cobalt acetate. When a composition and/or a layer or coating comprising the same is substantially free, essentially free, or completely free of cobalt, this includes cobalt ions or compounds containing cobalt in any form.
According to the present invention, the treatment composition may, in some instances, be substantially free, or in some instances, essentially free, or in some instances, completely free, of vanadium ions or vanadium-containing compounds. As used herein, “vanadium-containing compounds” include compounds, complexes or salts containing the element vanadium such as, for example, vanadates and decavanadates that include counterions of alkali metal or ammonium cations, including, for example, sodium ammonium decavanadate. When a composition and/or a layer or coating comprising the same is substantially free, essentially free, or completely free of vanadium, this includes vanadium ions or compounds containing vanadium in any form.
Optionally, the second composition of the present invention may further comprise a nitrogen-containing heterocyclic compound. The nitrogen-containing heterocyclic compound may include cyclic compounds having 1 nitrogen atom, such as pyrroles, and azole compounds having 2 or more nitrogen atoms, such as pyrazoles, imidazoles, triazoles, tetrazoles and pentazoles, 1 nitrogen atom and 1 oxygen atom, such as oxazoles and isoxazoles, or 1 nitrogen atom and 1 sulfur atom, such as thiazoles and isothiazoles. Nonlimiting examples of suitable azole compounds include 2,5-dimercapto-1,3,4-thiadiazole (CAS:1072-71-5), 1H-benzotriazole (CAS: 95-14-7), 1H-1,2,3-triazole (CAS: 288-36-8), 2-amino-5-mercapto-1,3,4-thiadiazole (CAS: 2349-67-9), also named 5-amino-1,3,4-thiadiazole-2-thiol, and 2-amino-1,3,4-thiadiazole (CAS: 4005-51-0). In some embodiments, for example, the azole compound comprises 2,5-dimercapto-1,3,4-thiadiazole. Additionally, according to the present invention, the nitrogen-containing heterocyclic compound may be in the form of a salt, such as a sodium salt.
The nitrogen-containing heterocyclic compound may be present in the second composition at a concentration of at least 0.0005 g per liter of composition, such as at least 0.0008 g per liter of composition, such as at least 0.002 g per liter of composition, and in some instances, may be present in the second composition in an amount of no more than 3 g per liter of composition, such as no more than 0.2 g per liter of composition, such as no more than 0.1 g per liter of composition. According to the present invention, the nitrogen-containing heterocyclic compound may be present in the second composition (if at all) at a concentration of 0.0005 g per liter of composition to 3 g per liter of composition, such as 0.0008 g per liter of composition to 0.2 g per liter of composition, such as 0.002 g per liter of composition to 0.1 g per liter of composition.
According to the present invention, the second composition may comprise an aqueous medium and optionally may contain other materials such as at least one organic solvent. Nonlimiting examples of suitable such solvents include propylene glycol, ethylene glycol, glycerol, low molecular weight alcohols, and the like. When present, if at all, the organic solvent may be present in the second composition in an amount of at least 1 g solvent per liter of second composition, such as at least about 2 g solvent per liter of second solution, and in some instances, may be present in an amount of no more than 40 g solvent per liter of second composition, such as no more than 20 g solvent per liter of second solution. According to the present invention, the organic solvent may be present in the second composition, if at all, in an amount of 1 g solvent per liter of second composition to 40 g solvent per liter of second composition, such as 2 g solvent per liter of second composition to 20 g solvent per liter of second composition.
According to the present invention, the pH of the second composition may be at least 8, such as at least 9, such as at least 10, such as at least 11, and in some instances may be no higher than 13, such as no higher than 12, such as no higher than 11.5. According to the present invention, the pH of the second composition may be 8 to 13, such as 10 to 12, such as 11 to 11.5. The pH of the second composition may be adjusted using, for example, any acid and/or base as is necessary. According to the present invention, the pH of the second composition may be maintained through the inclusion of an acidic material, including carbon dioxide, water soluble and/or water dispersible acids, such as hydrochloric acid, nitric acid, sulfuric acid, and/or phosphoric acid. According to the present invention, the pH of the second composition may be maintained through the inclusion of a basic material, including water soluble and/or water dispersible bases, including carbonates such as Group I carbonates, Group II carbonates, hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, or ammonium hydroxide, ammonia, and/or amines such as triethylamine, methylethyl amine, or mixtures thereof.
As mentioned above, the second composition may comprise a carrier, often an aqueous medium, so that the composition is in the form of a solution or dispersion of the lithium cation in the carrier. According to the present invention, the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the invention, the solution or dispersion when applied to the metal substrate may be at a temperature ranging from 40° F. to about 160° F., such as 60° F. to 110° F. For example, the process of contacting the metal substrate with the second composition may be carried out at ambient or room temperature. The contact time is often from about 1 second to about 15 minutes, such as about 5 seconds to about 2 minutes.
According to the present invention, following the contacting with the second composition, the substrate optionally may be dried in place, e.g., air dried at room temperature or be dried with hot air, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as by drying the substrate in an oven at 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls. According to the present invention, the substrate surface may be partially, or in some instances, completely dried prior to any subsequent contact of the substrate surface with any water, solutions, compositions, or the like. As used herein with respect to a substrate surface, “completely dry” or “completely dried” means there is no moisture on the substrate surface visible to the human eye. According to the present invention, following the contacting with the second composition, the substrate (either wet or dried in place) optionally may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents in order to remove any residue and then optionally may be dried, for example air dried or dried with hot air as described in the preceding sentence. Acording to the present invention, such water rinses may be eliminated and the substrate (either wet or dried in place) may be contacted with subsequent treatment compositions.
Optionally, according to the present invention, following the contacting with the second composition, the substrate optionally is not rinsed or contacted with any aqueous solutions prior to contacting at least a portion of the substrate surface with subsequent treatment compositions to form films, layers, and/or coatings thereon (described below).
Optionally, according to the present invention, following the contacting with the second composition, the substrate optionally may be contacted with tap water, deionized water, RO water and/or any aqueous solution known to those of skill in the art of substrate treatment, wherein such water or aqueous solution may be at a temperature of room temperature (60° F.) to 212° F. The substrate then optionally may be dried, for example air dried or dried with hot air as described in the preceding paragraph such that the substrate surface may be partially, or in some instances, completely dried prior to any subsequent contact of the substrate surface with any water, solutions, compositions, or the like.
As mentioned above, the system and method of the present invention may comprise a third composition comprising a Group IVB metal cation. The third composition also may further comprise a Group IA metal cation and/or a Group VIB metal cation (together with the Group IVB metal cation, referred to collectively herein as “third composition metal cations”).
According to the present invention, the Group IA metal cation may comprise lithium; the Group IVB metal cation may comprise zirconium, titanium, hafnium, or combinations thereof; and the Group VIB metal may comprise molybdenum.
For example, the Group IVB metal cation used in the third composition may be a compound of zirconium, titanium, hafnium, or a mixture thereof. Suitable compounds of zirconium include, but are not limited to, hexafluorozirconic acid, alkali metal and ammonium salts thereof, ammonium zirconium carbonate, zirconyl nitrate, zirconyl sulfate, zirconium carboxylates and zirconium hydroxy carboxylates, such as zirconium acetate, zirconium oxalate, ammonium zirconium glycolate, ammonium zirconium lactate, ammonium zirconium citrate, zirconium basic carbonate, and mixtures thereof. Suitable compounds of titanium include, but are not limited to, fluorotitanic acid and its salts. A suitable compound of hafnium includes, but is not limited to, hafnium nitrate.
According to the present invention, the Group IVB metal cation may be present in the third composition in a total amount of at least 20 ppm metal (calculated as metal cation), based on total weight of the third composition, such as at least 50 ppm metal, or, in some cases, at least 70 ppm metal. According to the present invention, the Group IVB metal may be present in the third composition in a total amount of no more than 1000 ppm metal (calculated as metal cation), based on total weight of the third composition, such as no more than 600 ppm metal, or, in some cases, no more than 300 ppm metal. According to the present invention, the Group IVB metal cation may be present in the third composition in a total amount of 20 ppm metal to 1000 ppm metal (calculated as metal cation), based on total weight of the third composition, such as from 50 ppm metal to 600 ppm metal, such as from 70 ppm metal to 300 ppm metal. As used herein, the term “total amount,” when used with respect to the amount of Group IVB metal cation, means the sum of all Group IV metals present in the third composition.
According to the present invention, the third composition also may comprise a Group IA metal cation such as a lithium cation. According to the invention, the source of Group IA metal cation in the third composition may be in the form of a salt. Non-limiting examples of suitable lithium salts include lithium nitrate, lithium sulfate, lithium fluoride, lithium chloride, lithium hydroxide, lithium carbonate, lithium iodide, and combinations thereof.
According to the present invention, the Group I metal cation may be present in the third composition in an amount of at least 2 ppm (as metal cation), based on a total weight of the third composition, such as at least 5 ppm, such as at least 25 ppm, such as at least 75 ppm, and in some instances, may be present in amount of no more than 500 ppm (as metal cation), based on a total weight of the third composition, such as no more than 250 ppm, such as no more than 125 ppm, such as no more than 100 ppm. According to the present invention, the Group IA metal cation may be present in the third composition in an amount of 2 ppm to 500 ppm (as metal cation), based on a total weight of the third composition, such as 5 ppm to 250 ppm, such as 5 ppm to 125 ppm, such as 5 ppm to 25 ppm. The amount of Group IA metal cation in the third composition can range between the recited values inclusive of the recited values.
According to the present invention, the third composition may also comprise a Group VIB metal cation. According to the present invention, the source of Group VIB metal cation in the third composition may be in the form of a salt. Non-limiting examples of suitable molybdenum salts include sodium molybdate, lithium molybdate, calcium molybdate, potassium molybdate, ammonium molybdate, molybdenum chloride, molybdenum acetate, molybdenum sulfamate, molybdenum formate, molybdenum lactate, and combinations thereof.
According to the present invention, the Group VIB metal cation may be present in the third composition in an amount of at least 5 ppm (as metal cation), based on a total weight of the third composition, such as at least 25 ppm, such as 100 ppm, and in some instances, may be present in the third composition in an amount of no more than 500 ppm (as metal cation), based on total weight of the third composition, such as no more than 250 ppm, such as no more than 150 ppm. According to the present invention, the Group VIB metal cation may be present in the third composition in an amount of 5 ppm to 500 ppm (as metal cation), based on total weight of the third composition, such as 25 ppm to 250 ppm, such as 40 ppm to 120 ppm. The amount of Group VIB metal cation in the third composition can range between the recited values inclusive of the recited values.
According to the present invention, the third composition may further comprise an anion that may be suitable for forming a salt with the third composition metal cations, such as a halogen, a nitrate, a sulfate, a silicate (orthosilicates and metasilicates), carbonates, hydroxides, and the like.
According to the present invention, the nitrate may be present in the third composition, if at all, in an amount of at least 2 ppm, such as at least 50 ppm, such as at least 50 ppm, (calculated as nitrate anion) based on total weight of the third composition, and may be present in an amount of no more than 10,000 ppm, such as no more than 5000 ppm, such as no more than 2500 ppm, (calculated as nitrate anion) based on total weight of the third composition. According to the present invention, the halogen may be present in the third composition, if at all, in an amount of 2 ppm to 10,000 ppm, such as 25 ppm to 5000 ppm, such as 50 ppm to 2500 ppm, (calculated as nitrate anion) based on total weight of the third composition.
According to the present invention, the third composition also may comprise an electropositive metal ion. As used herein, the term “electropositive metal ion” refers to metal ions that will be reduced by the metal substrate being treated when the third solution contacts the surface of the metallic substrate. As will be appreciated by one skilled in the art, the tendency of chemical species to be reduced is called the reduction potential, is expressed in volts, and is measured relative to the standard hydrogen electrode, which is arbitrarily assigned a reduction potential of zero. The reduction potential for several elements is set forth in Table 1 below (according to the CRC 82nd Edition, 2001-2002). An element or ion is more easily reduced than another element or ion if it has a voltage value, E*, in the following table, that is more positive than the elements or ions to which it is being compared.
Thus, as will be apparent, when the metal substrate comprises one of the materials listed earlier, such as cold rolled steel, hot rolled steel, steel coated with zinc metal, zinc compounds, or zinc alloys, hot-dipped galvanized steel, galvanealed steel, steel plated with zinc alloy, aluminum alloys, aluminum plated steel, aluminum alloy plated steel, magnesium and magnesium alloys, suitable electropositive metal ions for deposition thereon include, for example, nickel, copper, silver, and gold, as well mixtures thereof.
According to the present invention, when the electropositive metal ion comprises copper, both soluble and insoluble compounds may serve as a source of copper ions in the third compositions. For example, the supplying source of copper ions in the third composition may be a water soluble copper compound. Specific examples of such compounds include, but are not limited to, copper sulfate, copper nitrate, copper thiocyanate, disodium copper ethylenediaminetetraacetate tetrahydrate, copper bromide, copper oxide, copper hydroxide, copper chloride, copper fluoride, copper gluconate, copper citrate, copper lauroyl sarcosinate, copper lactate, copper oxalate, copper tartrate, copper malate, copper succinate, copper malonate, copper maleate, copper benzoate, copper salicylate, copper amino acid complexes, copper fumarate, copper glycerophosphate, sodium copper chlorophyllin, copper fluorosilicate, copper fluoroborate and copper iodate, as well as copper salts of carboxylic acids such as in the homologous series formic acid to decanoic acid, and copper salts of polybasic acids in the series oxalic acid to suberic acid.
When copper ions supplied from such a water-soluble copper compound are precipitated as an impurity in the form of copper sulfate, copper oxide, etc., it may be desirable to add a complexing agent that suppresses the precipitation of copper ions, thus stabilizing them as a copper complex in the composition.
According to the present invention, the copper compound may be added as a copper complex salt such as or Cu-EDTA, which can be present stably in the third composition on its own, but it is also possible to form a copper complex that can be present stably in the third composition by combining a complexing agent with a compound that is difficult to solubilize on its own. An example thereof includes a Cu-EDTA complex formed by a combination of CuSO4 and EDTA.2Na.
According to the present invention, the electropositive metal ion may be present in the third composition in an amount of at least 2 ppm (calculated as metal ion), based on the total weight of the third composition, such as at least 4 ppm, such as at least 6 ppm, such as at least 8 ppm, such as at least 10 ppm. According to the present invention, the electropositive metal ion may be present in the third composition in an amount of no more than 100 ppm (calculated as metal ion), based on the total weight of the third composition, such as no more than 80 ppm, such as no more than 60 ppm, such as no more than 40 ppm, such as no more than 20 ppm. According to the present invention, the electropositive metal ion may be present in the third composition in an amount of from 2 ppm to 100 ppm (calculated as metal ion), based on the total weight of the third composition, such as from 4 ppm to 80 ppm, such as from 6 ppm to 60 ppm, such as from 8 ppm to 40 ppm, The amount of electropositive metal ion in the third composition can range between the recited values inclusive of the recited values.
According to the present invention, a source of fluoride may be present in the third composition. As used herein the amount of fluoride disclosed or reported in the third composition is referred to as “free fluoride,” as measured in part per millions of fluoride. Free fluoride is defined herein as being able to be measured by a fluoride-selective ISE. In addition to free fluoride, a third may also contain “bound fluoride, which is described above. The sum of the concentrations of the bound and free fluoride equal the total fluoride, which can be determined as described herein. The total fluoride in the third composition can be supplied by hydrofluoric acid, as well as alkali metal and ammonium fluorides or hydrogen fluorides. Additionally, total fluoride in the third composition may be derived from Group IVB metals present in the third composition, including, for example, hexafluorozirconic acid or hexafluorotitanic acid. Other complex fluorides, such as H2SiF6 or HBF4, can be added to the third composition to supply total fluoride. The skilled artisan will understand that the presence of free fluoride in the third bath can impact third deposition and etching of the substrate, hence it is critical to measure this bath parameter. The levels of free fluoride will depend on the pH and the addition of chelators into the third bath and indicates the degree of fluoride association with the metal ions/protons present in the third bath. For example, third compositions of identical total fluoride levels can have different free fluoride levels which will be influenced by the pH and chelators present in the third solution.
According to the present invention, the free fluoride of the third composition may be present in an amount of at least 15 ppm, based on a total weight of the third composition, such as at least 50 ppm free fluoride, such as at least 100 ppm free fluoride, such as at least 200 ppm free fluoride. According to the present invention, the free fluoride of the third composition may be present in an amount of no more than 2500 ppm, based on a total weight of the third composition, such as no more than 1000 ppm free fluoride, such as no more than 500 ppm free fluoride, such as no more than 250 ppm free fluoride. According to the present invention, the free fluoride of the third composition may be present in an amount of 15 ppm free fluoride to 2500 ppm free fluoride, based on a total weight of the third composition, such as 50 ppm fluoride to 1000 ppm, such as no more than 200 ppm free fluoride to 500 ppm free fluoride, such as no more than 100 ppm free fluoride to 250 ppm free fluoride.
The third composition may further comprise an amino compound. The amino compound can be primary, secondary, tertiary, or quaternary amine. Specific examples of the alpha amino compounds can be sarcosine, glycine and oleyl imidazoline. According to the present invention, the alpha amino acid compound may be a substituted or an unsubstituted glycine. The substituted glycine can be sarcosine, iminodiacetic acid, leucine or tyrosine. Illustrative but non-limiting examples of the beta amino acid compounds include taurine and N-methyl taurine. An illustrative but non-limiting example of the gamma amino acid compound includes gamma aminobutyric acid. Illustrative but non-limiting examples of the cyclic amino compound having an amine group and an acid group on the same ring include aminobenzoic acid and derivatives thereof. Illustrative but non-limiting examples of the beta amino alcohol compounds includes imidazoline and derivatives thereof, choline, triethanolamine, diethanol glycine and 2-amino-2-ethyl-1,3-propanediol. An illustrative but non-limiting example of the gamma amino alcohol compounds includes aminopropanol. Illustrative but non-limiting examples of the cyclic amino compounds having an amine group and a hydroxyl group on the same ring includes amino phenols and derivatives thereof.
The amino compound may be present in the third composition in an amount of at least 50 ppm based on total weight of the third composition such as at least 100 ppm, and in some instances may be present in an amount of no more than 100,000 ppm, such as no more than 10,000 ppm. According to the present invention, the amino compound may be present in the third composition in an amount of 50 ppm to 100,000 ppm based on total weight of the third composition, such as 100 ppm to 10,000 ppm.
According to the present invention, the third composition may, in some instances, comprise an oxidizing agent. Non-limiting examples of the oxidizing agent include peroxides, persulfates, perchlorates, chlorates, hypochlorite, nitric acid, sparged oxygen, bromates, peroxi-benzoates, ozone, or combinations thereof. According to the present invention, the oxidizing agent may be present, if at all, in an amount of at least 50 ppm, such as at least 500 ppm, based on total weight of the third composition, and in some instances, may be present in an amount of no more than 13,000 ppm, such as no more than 3000 ppm, based on total weight of the third composition. In some instances, the oxidizing agent may be present in the third composition, if at all, in an amount of 100 ppm to 13,000 ppm, such as 500 ppm to 3000 ppm, based on total weight of the third composition. As used herein, the term “oxidizing agent,” when used with respect to a component of the third composition, refers to a chemical which is capable of oxidizing at least one of: a metal present in the substrate which is contacted by the third composition, and/or a metal-complexing agent present in the third composition. As used herein with respect to “oxidizing agent,” the phrase “capable of oxidizing” means capable of removing electrons from an atom or a molecule present in the substrate or the third composition, as the case may be, thereby decreasing the number of electrons of such atom or molecule.
According to the present invention, the third composition may exclude chromium or chromium-containing compounds. As used herein, the term “chromium-containing compound” refers to materials that include trivalent and/or hexavalent chromium. Non-limiting examples of such materials include chromic acid, chromium trioxide, chromic acid anhydride, dichromate salts, such as ammonium dichromate, sodium dichromate, potassium dichromate, and calcium, barium, magnesium, zinc, cadmium, strontium dichromate, chromium(III) sulfate, chromium(III) chloride, and chromium(III) nitrate. When a third composition and/or a coating or a layer, respectively, formed from the same is substantially free, essentially free, or completely free of chromium, this includes chromium in any form, such as, but not limited to, the trivalent and hexavalent chromium-containing compounds listed above.
Thus, optionally, according to the present invention, the present third compositions and/or coatings or layers, respectively, deposited from the same may be substantially free, may be essentially free, and/or may be completely free of one or more of any of the elements or compounds listed in the preceding paragraph. A third composition and/or coating or layer, respectively, formed from the same that is substantially free of chromium or derivatives thereof means that chromium or derivatives thereof are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the third composition; in the case of chromium, this may further include that the element or compounds thereof are not present in the third compositions and/or coatings or layers, respectively, formed from the same in such a level that it causes a burden on the environment. The term “substantially free” means that the third compositions and/or coating or layers, respectively, formed from the same contain less than 10 ppm of any or all of the elements or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the third compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppm of any or all of the elements or compounds listed in the preceding paragraph, if any at all. The term “completely free” means that the third compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppb of any or all of the elements or compounds listed in the preceding paragraph, if any at all.
According to the present invention, the third composition may, in some instances, exclude phosphate ions or phosphate-containing compounds and/or the formation of sludge, such as aluminum phosphate, iron phosphate, and/or zinc phosphate, formed in the case of using a treating agent based on zinc phosphate. As used herein, “phosphate-containing compounds” include compounds containing the element phosphorous such as ortho phosphate, pyrophosphate, metaphosphate, tripolyphosphate, organophosphonates, and the like, and can include, but are not limited to, monovalent, divalent, or trivalent cations such as: sodium, potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. When a composition and/or a layer or coating comprising the same is substantially free, essentially free, or completely free of phosphate, this includes phosphate ions or compounds containing phosphate in any form.
Thus, according to the present invention, third composition and/or layers deposited from the same may be substantially free, or in some cases may be essentially free, or in some cases may be completely free, of one or more of any of the ions or compounds listed in the preceding paragraph. A third composition and/or layers deposited from the same that is substantially free of phosphate means that phosphate ions or compounds containing phosphate are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the composition; this may further include that phosphate is not present in the third compositions and/or layers deposited from the same in such a level that they cause a burden on the environment. The term “substantially free” means that the third compositions and/or layers deposited from the same contain less than 5 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the third compositions and/or layers comprising the same contain less than 1 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph. The term “completely free” means that the third compositions and/or layers comprising the same contain less than 1 ppb of any or all of the phosphate anions or compounds listed in the preceding paragraph, if any at all.
Optionally, according to the present invention, the third composition may further comprise a source of phosphate ions. For clarity, when used herein, “phosphate ions” refers to phosphate ions that derive from or originate from inorganic phosphate compounds. For example, in some instances, phosphate ions may be present in an amount of greater than 5 ppm, based on total weight of the third composition, such as 10 ppm, such as 20 ppm. In some instances, phosphate ions may be present in an amount of no more than 60 ppm, based on total weight of the third composition, such as no more than 40 ppm, such as no more than 30 ppm. In some instances, phosphate ions may be present in an amount of from 5 ppm to 60 ppm, based on total weight of the third composition, such as from 10 ppm to 40 ppm, such as from 20 ppm to 30 ppm.
According to the present invention, the pH of the third composition may be 6.5 or less, such as 5.5 or less, such as 4.5 or less, such as 3.5 or less. According to the present invention, the pH of the third composition may, in some instances, be 2.0 to 6.5, such as 3 to 4.5, and may be adjusted using, for example, any acid and/or base as is necessary. According to the present invention, the pH of the third composition may be maintained through the inclusion of an acidic material, including water soluble and/or water dispersible acids, such as nitric acid, sulfuric acid, and/or phosphoric acid. According to the present invention, the pH of the composition may be maintained through the inclusion of a basic material, including water soluble and/or water dispersible bases, such as sodium hydroxide, sodium carbonate, potassium hydroxide, ammonium hydroxide, ammonia, and/or amines such as triethylamine, methylethyl amine, or mixtures thereof.
According to the present invention, the third composition also may further comprise a resinous binder. Suitable resins include reaction products of one or more alkanolamines and an epoxy-functional material containing at least two epoxy groups, such as those disclosed in U.S. Pat. No. 5,653,823. In some cases, such resins contain beta hydroxy ester, imide, or sulfide functionality, incorporated by using dimethylolpropionic acid, phthalimide, or mercaptoglycerine as an additional reactant in the preparation of the resin. Alternatively, the reaction product can for instance be that of the diglycidyl ether of Bisphenol A (commercially available e.g. from Shell Chemical Company as EPON 880), dimethylol propionic acid, and diethanolamine in a 0.6 to 5.0:0.05 to 5.5:1 mole ratio. Other suitable resinous binders include water soluble and water dispersible polyacrylic acids such as those disclosed in U.S. Pat. Nos. 3,912,548 and 5,328,525; phenol formaldehyde resins such as those described in U.S. Pat. No. 5,662,746; water soluble polyamides such as those disclosed in WO 95/33869; copolymers of maleic or acrylic acid with allyl ether such as those described in Canadian patent application 2,087,352; and water soluble and dispersible resins including epoxy resins, aminoplasts, phenol-formaldehyde resins, tannins, and polyvinyl phenols such as those discussed in U.S. Pat. No. 5,449,415
According to the present invention, the resinous binder often may be present in the third composition in an amount of 0.005 percent to 30 percent by weight, such as 0.5 to 3 percent by weight, based on the total weight of the composition. Alternatively, according to the present invention, the third composition may be substantially free or, in some cases, completely free of any resinous binder. As used herein, the term “substantially free”, when used with reference to the absence of resinous binder in the third composition, means that, if present at all, any resinous binder is present in the third composition in a trace amount of less than 0.005 percent by weight, based on total weight of the composition. As used herein, the term “completely free” means that there is no resinous binder in the third composition at all.
The third composition may comprise an aqueous medium and may optionally contain other materials such as nonionic surfactants and auxiliaries conventionally used in the art of third compositions. In the aqueous medium, water dispersible organic solvents, for example, alcohols with up to about 8 carbon atoms such as methanol, isopropanol, and the like, may be present; or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol, or propylene glycol, and the like. When present, water dispersible organic solvents are typically used in amounts up to about ten percent by volume, based on the total volume of aqueous medium.
Other optional materials include surfactants that function as defoamers or substrate wetting agents. Anionic, cationic, amphoteric, and/or nonionic surfactants may be used. Defoaming surfactants may optionally be present at levels up to 1 weight percent, such as up to 0.1 percent by weight, and wetting agents are typically present at levels up to 2 percent, such as up to 0.5 percent by weight, based on the total weight of the third composition.
Optionally, according to the present invention, the third composition and/or films deposited or formed therefrom may further comprise silicon, such as silanes, silicas, silicates, and the like, in amounts of at least 10 ppm, based on total weight of the third composition, such as at least 20 ppm, such as at least 50 ppm. According to the present invention, the third composition and/or films deposited or formed therefrom may comprise silicon in amounts of less than 500 ppm, based on total weight of the third composition, such as less than 250 ppm, such as less than 100 ppm. According to the present invention, the third composition and/or films deposited or formed therefrom may comprise silicon in amounts of 10 ppm to 500 ppm, based on total weight of the third composition, such as 20 ppm to 250 ppm, such as 50 ppm to 100 ppm. Alternatively, the third composition of the present invention and/or films deposited or formed therefrom may be substantially free, or, in some cases, completely free of silicon.
The third composition may comprise a carrier, often an aqueous medium, so that the composition is in the form of a solution or dispersion of the Group IVB metal in the carrier. According to the present invention, the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the invention, the solution or dispersion when applied to the metal substrate is at a temperature ranging from 40° F. to 185° F., such as 60° F. to 110° F., such as 70° F. to 90° F. For example, the third process may be carried out at ambient or room temperature. The contact time is often from 5thirds to 15 minutes, such as 10 thirds to 10 minutes, such as 15 thirds to 3 minutes.
Following the contacting with the third composition, the substrate may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents in order to remove any residue. The substrate optionally may be air dried at room temperature or may be dried with hot air, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as by drying the substrate in an oven at 15° C. to 200° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls. According to the present invention, following the contacting with the third composition, the substrate optionally may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents in order to remove any residue and then optionally may be dried, for example air dried or dried with hot air as described in the preceding sentence.
According to the present invention the film coverage of the residue of the third coating composition generally ranges typically from 1 to 1000 milligrams per square meter (mg/m2), for example, from 10 to 400 mg/m2. The thickness of the third coating may for instance be less than 1 micrometer, for example from 1 to 500 nanometers, or from 10 to 300 nanometers. Coating weights may be determined by removing the film from the substrate and determining the elemental composition using a variety of analytical techniques (such as XRF, ICP, etc.). Pretreatment thickness can be determined using a handful of analytical techniques including, but not limited to XPS depth profiling or TEM.
According to the present invention, at least a portion of the substrate surface may be cleaned and/or deoxidized prior to contacting at least a portion of the substrate surface with one of the compositions described above, in order to remove grease, dirt, and/or other extraneous matter. At least a portion of the surface of the substrate may be cleaned by physical and/or chemical means, such as mechanically abrading the surface and/or cleaning/degreasing the surface with commercially available alkaline or acidic cleaning agents that are well known to those skilled in the art. Examples of alkaline cleaners suitable for use in the present invention include Chemkleen™ 166HP, 166M/C, 177, 490MX, 2010LP, and Surface Prep 1 (SP1), Ultrax 32, Ultrax 97, Ultrax 29, and Ultrax92D, each of which are commercially available from PPG Industries, Inc. (Cleveland, Ohio), and any of the DFM Series, RECC 1001, and 88X1002 cleaners commercially available from PRC-DeSoto International, Sylmar, Calif.), and Turco 4215-NCLT and Ridolene (commercially available from Henkel Technologies, Madison Heights, Mich.). Such cleaners are often preceded or followed by a water rinse, such as with tap water, distilled water, or combinations thereof.
As mentioned above, according to the present invention, at least a portion of the cleaned substrate surface may be deoxidized, mechanically and/or chemically. As used herein, the term “deoxidize” means removal of the oxide layer found on the surface of the substrate in order to promote uniform deposition of the conversion composition (described below), as well as to promote the adhesion of the conversion composition coating to the substrate surface. Suitable deoxidizers will be familiar to those skilled in the art. A typical mechanical deoxidizer may be uniform roughening of the substrate surface, such as by using a scouring or cleaning pad. Typical chemical deoxidizers include, for example, acid-based deoxidizers such as phosphoric acid, nitric acid, fluoroboric acid, sulfuric acid, chromic acid, hydrofluoric acid, and ammonium bifluoride, or Amchem 7/17 deoxidizers (available from Henkel Technologies, Madison Heights, Mich.), OAKITE DEOXIDIZER LNC (commercially available from Chemetall), TURCO DEOXIDIZER 6 (commercially available from Henkel), or combinations thereof. Often, the chemical deoxidizer comprises a carrier, often an aqueous medium, so that the deoxidizer may be in the form of a solution or dispersion in the carrier, in which case the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the present invention, the skilled artisan will select a temperature range of the solution or dispersion, when applied to the metal substrate, based on etch rates, for example, at a temperature ranging from 50° F. to 150° F. (10° C. to 66° C.), such as from 70° F. to 130° F. (21° C. to 54° C.), such as from 80° F. to 120° F. (27° C. to 49° C.). The contact time may be from 30 seconds to 20 minutes, such as 1 minute to 15 minutes, such as 90 seconds to 12 minutes, such as 3 minutes to 9 minutes.
Following the cleaning and/or deoxidizing step(s), the substrate optionally may be rinsed with tap water, deionized water, and/or an aqueous solution of rinsing agents in order to remove any residue. According to the present invention, the wet substrate surface may be treated with a conversion composition (described below) and/or a sealing composition (described above), or the substrate may be dried prior to treating the substrate surface, such as air dried, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls.
As mentioned above, at least a portion of the substrate surface optionally may be contacted with a second or a third composition prior to or after being contacted with the first composition of the present invention.
Color measurements can be determined for substrates treated with the first composition (cerium) to characterize the degree of yellowing of the treated substrate. Color parameters may be determined using an Xrite Ci7800 Benchtop Sphere Spectrophotometer, 25 mm aperture available from X-Rite, Incorporated, Grandville, Mich. or such similar instruments. The Xrite Ci7800 instrument measures according to the L*a*b* color space theory. The term b* indicates a more yellow hue for positive values and a more blue hue for negative values. The term a* indicates a more green hue when negative and a more red hue when positive. The term L* indicates a black hue when L*=0 and a white hue when L*=100.
According to the present invention, substrate that was pretreated with the first composition had b* values that typically range from 9 to 15. Application of a heating step significantly reduced the b* value of substrate contacted with the first composition, for example, a b* value that ranges from −20 to +8, such −15 to +5, such as −10 to +4, such as −5 to +2.5. Substrate treated according to the present invention may have a YI-E313 (yellow index) as determined by ASTM E313-00 of, for example, +5 to +22 prior to heating and after heat treatment, of +2 to +10, such +3 to +9, such as +4 to +8.
The effect of heating a panel after contacting with a cerium-containing composition has minimal effect on the values of a* and L*. Values for a*, regardless of heat treatment will range from −15 to +15, such as −10 to +10, such as −5 to +5. L* values, regardless of heat treatment will range from 50 to 90, such as 60 to 80.
According to the present invention, disclosed herein is a substrate comprising, or in some instances consisting essentially of, or in some instances consisting of: a film formed from a pretreatment composition comprising, or in some cases consisting essentially of, or in some instances consisting of, a lanthanide and an oxidizing agent, wherein the level of the lanthanide in the film is at least 100 counts greater than on a surface of a substrate that does not have the film thereon as measured by X-ray fluorescence (60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.5 μs).
According to the present invention, the level of the lanthanide series element in the film formed on the substrate surface from the pretreatment composition is at least 100 counts greater than on a surface of a substrate that does not have the film thereon as measured by X-ray fluorescence (60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.5 μs). For example, the lanthanide series element may be present in the film formed on the substrate surface, as shown by counts of greater than 340 counts, such as greater than 500 counts, such as greater than 1000 counts, such as greater than 1200 counts, as measured by X-ray fluorescence (60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.5 μs). It has been surprisingly discovered herein that pretreatment of a sanded substrate with the pretreatment composition of the present invention surprisingly resulted in superior corrosion performance compared to an unsanded substrate pretreated with conventional pretreatment composition.
According to the present invention, the substrate having the film formed from the pretreatment composition has at least a 5% decrease in scribe creep on the substrate surface compared to a substrate treated with a zirconium-containing pretreatment further including lithium and molybdenum (ASTM-B 368-09 Copper Acetic Acid Salt Spray, 480 hours).
It has been surprisingly discovered that, whereas a cured electrocoated panel treated with a zirconium-containing pretreatment composition is visibly yellow to the naked eye, in contrast, a cured electrocoated panel treated with a lanthanide-containing pretreatment composition is not visibly yellow to the naked eye. This result was unexpected.
Furthermore, also surprisingly, it has been discovered that heating a substrate pretreated with the conversion composition of the present invention at a temperature of 110 C to 232 C surprisingly reduced the yellowing seen on unheated panels pretreated with the conversion composition of the present invention. For example, it has been surprisingly discovered that the b* value and YI-E313 value of panels (sanded and unsanded) treated with the conversion composition of the present invention were significantly reduced when such panels were pretreated with the conversion composition of the present invention, and were even further reduced when such panels were heated at a temperature of 110 C to 232 C.
It also has been surprisingly discovered that an electrocoated panel pretreated with a pretreatment composition comprising cerium results in a 27% reduction in the scribe creep following 480 hours exposure to copper acetic salt spray (ASTM-B 368-09) compared to an electrocoated panel pretreated with a zirconium-containing pretreatment. This result was unexpected.
It also has been surprisingly discovered that an electrocoated panel pretreated with a pretreatment composition comprising cerium results in a 65% reduction in the scribe creep following 480 hours exposure to copper acetic salt spray (ASTM-B 368-09) compared to an electrocoated panel pretreated with a zinc phosphate pretreatment. This result was unexpected.
According to the present invention, the coating composition may comprise a thermosetting film-forming resin or a thermoplastic film-forming resin. As used herein, the term “film-forming resin” refers to resins that can form a self-supporting continuous film on at least a horizontal surface of a substrate upon removal of any diluents or carriers present in the composition or upon curing at ambient or elevated temperature. Conventional film-forming resins that may be used include, without limitation, those typically used in automotive OEM coating compositions, automotive refinish coating compositions, industrial coating compositions, architectural coating compositions, coil coating compositions, and aerospace coating compositions, among others. As used herein, the term “thermosetting” refers to resins that “set” irreversibly upon curing or crosslinking, wherein the polymer chains of the polymeric components are joined together by covalent bonds. This property is usually associated with a cross-linking reaction of the composition constituents often induced, for example, by heat or radiation. Curing or crosslinking reactions also may be carried out under ambient conditions. Once cured or crosslinked, a thermosetting resin will not melt upon the application of heat and is insoluble in solvents. As used herein, the term “thermoplastic” refers to resins that comprise polymeric components that are not joined by covalent bonds and thereby can undergo liquid flow upon heating and are soluble in solvents.
As previously indicated, according to the present invention, an electrodepositable coating composition comprising a water-dispersible, ionic salt group-containing film-forming resin that may be deposited onto the substrate by an electrocoating step wherein the electrodepositable coating composition is deposited onto the metal substrate by electrodeposition.
The ionic salt group-containing film-forming polymer may comprise a cationic salt group containing film-forming polymer for use in a cationic electrodepositable coating composition. As used herein, the term “cationic salt group-containing film-forming polymer” refers to polymers that include at least partially neutralized cationic groups, such as sulfonium groups and ammonium groups, that impart a positive charge. The cationic salt group-containing film-forming polymer may comprise active hydrogen functional groups, including, for example, hydroxyl groups, primary or secondary amine groups, and thiol groups. Cationic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, cationic salt group-containing film-forming polymers. Examples of polymers that are suitable for use as the cationic salt group-containing film-forming polymer include, but are not limited to, alkyd polymers, acrylics, polyepoxides, polyamides, polyurethanes, polyureas, polyethers, and polyesters, among others.
The cationic salt group-containing film-forming polymer may be present in the cationic electrodepositable coating composition in an amount of 40% to 90% by weight, such as 50% to 80% by weight, such as 60% to 75% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. As used herein, the “resin solids” include the ionic salt group-containing film-forming polymer, curing agent, and any additional water-dispersible non-pigmented component(s) present in the electrodepositable coating composition.
Alternatively, the ionic salt group containing film-forming polymer may comprise an anionic salt group containing film-forming polymer for use in an anionic electrodepositable coating composition. As used herein, the term “anionic salt group containing film-forming polymer” refers to an anionic polymer comprising at least partially neutralized anionic functional groups, such as carboxylic acid and phosphoric acid groups that impart a negative charge. The anionic salt group-containing film-forming polymer may comprise active hydrogen functional groups. Anionic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, anionic salt group-containing film-forming polymers.
The anionic salt group-containing film-forming polymer may comprise base-solubilized, carboxylic acid group-containing film-forming polymers such as the reaction product or adduct of a drying oil or semi-drying fatty acid ester with a dicarboxylic acid or anhydride; and the reaction product of a fatty acid ester, unsaturated acid or anhydride and any additional unsaturated modifying materials which are further reacted with polyol. Also suitable are the at least partially neutralized interpolymers of hydroxy-alkyl esters of unsaturated carboxylic acids, unsaturated carboxylic acid and at least one other ethylenically unsaturated monomer. Still another suitable anionic electrodepositable resin comprises an alkyd-aminoplast vehicle, i.e., a vehicle containing an alkyd resin and an amine-aldehyde resin. Another suitable anionic electrodepositable resin composition comprises mixed esters of a resinous polyol. Other acid functional polymers may also be used such as phosphatized polyepoxide or phosphatized acrylic polymers. Exemplary phosphatized polyepoxides are disclosed in U.S. Patent Application Publication No. 2009-0045071 at [0004]-[0015] and U.S. patent application Ser. No. 13/232,093 at [0014]-[0040], the cited portions of which being incorporated herein by reference.
The anionic salt group-containing film-forming polymer may be present in the anionic electrodepositable coating composition in an amount 50% to 90%, such as 55% to 80%, such as 60% to 75%, based on the total weight of the resin solids of the electrodepositable coating composition.
The electrodepositable coating composition may further comprise a curing agent. The curing agent may react with the reactive groups, such as active hydrogen groups, of the ionic salt group-containing film-forming polymer to effectuate cure of the coating composition to form a coating. Non-limiting examples of suitable curing agents are at least partially blocked polyisocyanates, aminoplast resins and phenoplast resins, such as phenolformaldehyde condensates including allyl ether derivatives thereof.
The curing agent may be present in the cationic electrodepositable coating composition in an amount of 10% to 60% by weight, such as 20% to 50% by weight, such as 25% to 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. Alternatively, the curing agent may be present in the anionic electrodepositable coating composition in an amount of 10% to 50% by weight, such as 20% to 45% by weight, such as 25% to 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition.
The electrodepositable coating composition may further comprise other optional ingredients, such as a pigment composition and, if desired, various additives such as fillers, plasticizers, anti-oxidants, biocides, UV light absorbers and stabilizers, hindered amine light stabilizers, defoamers, fungicides, dispersing aids, flow control agents, surfactants, wetting agents, or combinations thereof.
The electrodepositable coating composition may comprise water and/or one or more organic solvent(s). Water can for example be present in amounts of 40% to 90% by weight, such as 50% to 75% by weight, based on total weight of the electrodepositable coating composition. If used, the organic solvents may typically be present in an amount of less than 10% by weight, such as less than 5% by weight, based on total weight of the electrodepositable coating composition. The electrodepositable coating composition may in particular be provided in the form of an aqueous dispersion. The total solids content of the electrodepositable coating composition may be from 1% to 50% by weight, such as 5% to 40% by weight, such as 5% to 20% by weight, based on the total weight of the electrodepositable coating composition. As used herein, “total solids” refers to the non-volatile content of the electrodepositable coating composition, i.e., materials which will not volatilize when heated to 110° C. for 15 minutes.
The cationic electrodepositable coating composition may be deposited upon an electrically conductive substrate by placing the composition in contact with an electrically conductive cathode and an electrically conductive anode, with the surface to be coated being the cathode. Alternatively, the anionic electrodepositable coating composition may be deposited upon an electrically conductive substrate by placing the composition in contact with an electrically conductive cathode and an electrically conductive anode, with the surface to be coated being the anode. An adherent film of the electrodepositable coating composition is deposited in a substantially continuous manner on the cathode or anode, respectively, when a sufficient voltage is impressed between the electrodes. The applied voltage may be varied and can be, for example, as low as one volt to as high as several thousand volts, such as between 50 and 500 volts. Current density is usually between 1.0 ampere and 15 amperes per square foot (10.8 to 161.5 amperes per square meter) and tends to decrease quickly during the electrodeposition process, indicating formation of a continuous self-insulating film.
Once the cationic or anionic electrodepositable coating composition is electrodeposited over at least a portion of the electroconductive substrate, the coated substrate is heated to a temperature and for a time sufficient to cure the electrodeposited coating on the substrate. For cationic electrodeposition, the coated substrate may be heated to a temperature ranging from 110° C. to 232° C., such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.). For anionic electrodeposition, the coated substrate may be heated to a temperature ranging from 200° F. to 450° F. (93° C. to 232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.), such as 200° F. to 210.2° F. (93° C. to 99° C.). The curing time may be dependent upon the curing temperature as well as other variables, for example, the film thickness of the electrodeposited coating, level and type of catalyst present in the composition and the like. For example, the curing time can range from 10 minutes to 60 minutes, such as 20 to 40 minutes. The thickness of the resultant cured electrodeposited coating may range from 2 to 50 microns.
Alternatively, as mentioned above, according to the present invention, after the substrate has been contacted with the sealing composition, a powder coating composition may then be deposited onto at least a portion of the surface of the substrate. As used herein, “powder coating composition” refers to a coating composition which is completely free of water and/or solvent. Accordingly, the powder coating composition disclosed herein is not synonymous to waterborne and/or solvent-borne coating compositions known in the art.
According to the present invention, the powder coating composition may comprise (a) a film forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. Examples of powder coating compositions that may be used in the present invention include the polyester-based ENVIROCRON line of powder coating compositions (commercially available from PPG Industries, Inc.) or epoxy-polyester hybrid powder coating compositions. Alternative examples of powder coating compositions that may be used in the present invention include low temperature cure thermosetting powder coating compositions comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,470,752, assigned to PPG Industries, Inc. and incorporated herein by reference); curable powder coating compositions generally comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,432,333, assigned to PPG Industries, Inc. and incorporated herein by reference); and those comprising a solid particulate mixture of a reactive group-containing polymer having a Tg of at least 30° C. (such as those described in U.S. Pat. No. 6,797,387, assigned to PPG Industries, Inc. and incorporated herein by reference).
After deposition of the powder coating composition, the coating is often heated to cure the deposited composition. The heating or curing operation is often carried out at a temperature in the range of from 150° C. to 200° C., such as from 170° C. to 190° C., for a period of time ranging from 10 to 20 minutes. According to the invention, the thickness of the resultant film is from 50 microns to 125 microns.
As mentioned above, according to the present invention, the coating composition may be a liquid coating composition. As used herein, “liquid coating composition” refers to a coating composition which contains a portion of water and/or solvent. Accordingly, the liquid coating composition disclosed herein is synonymous to waterborne and/or solventborne coating compositions known in the art.
According to the present invention, the liquid coating composition may comprise, for example, (a) a film forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. In other examples, the liquid coating may contain a film forming polymer that may react with oxygen in the air or coalesce into a film with the evaporation of water and/or solvents. These film forming mechanisms may require or be accelerated by the application of heat or some type of radiation such as Ultraviolet or Infrared. Examples of liquid coating compositions that may be used in the present invention include the SPECTRACRON® line of solvent based coating compositions, the AQUACRON® line of waterbased coating compositions, and the RAYCRON® line of UV cured coatings (all commercially available from PPG Industries, Inc.).
Suitable film forming polymers that may be used in the liquid coating composition of the present invention may comprise a (poly)ester, an alkyd, a (poly)urethane, an isocyanurate, a (poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane, or combinations thereof.
According to the present invention, the substrate that has been contacted with the sealing composition may also be contacted with a primer composition and/or a topcoat composition. The primer coat may be, for examples, chromate-based primers and advanced performance topcoats. According to the present invention, the primer coat can be a conventional chromate based primer coat, such as those available from PPG Industries, Inc. (product code 44GN072), or a chrome-free primer such as those available from PPG (DESOPRIME CA7502, DESOPRIME CA7521, Deft 02GN083, Deft 02GN084). Alternately, the primer coat can be a chromate-free primer coat, such as the coating compositions described in U.S. patent application Ser. No. 10/758,973, titled “CORROSION RESISTANT COATINGS CONTAINING CARBON”, and U.S. patent application Ser. Nos. 10/758,972, and 10/758,972, both titled “CORROSION RESISTANT COATINGS”, all of which are incorporated herein by reference, and other chrome-free primers that are known in the art, and which can pass the military requirement of MIL-PRF-85582 Class N or MIL-PRF-23377 Class N may also be used with the current invention.
As mentioned above, the substrate of the present invention also may comprise a topcoat. As used herein, the term “topcoat” refers to a mixture of binder(s) which can be an organic or inorganic based polymer or a blend of polymers, typically at least one pigment, can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. A topcoat is typically the coating layer in a single or multi-layer coating system whose outer surface is exposed to the atmosphere or environment, and its inner surface is in contact with another coating layer or polymeric substrate. Examples of suitable topcoats include those conforming to MIL-PRF-85285D, such as those available from PPG (Deft 03W127A and Deft 03GY292). According to the present invention, the topcoat may be an advanced performance topcoat, such as those available from PPG (Defthane® ELT™ 99GY001 and 99W009). However, other topcoats and advanced performance topcoats can be used in the present invention as will be understood by those of skill in the art with reference to this disclosure.
According to the present invention, the metal substrate also may comprise a self-priming topcoat, or an enhanced self-priming topcoat. The term “self-priming topcoat”, also referred to as a “direct to substrate” or “direct to metal” coating, refers to a mixture of a binder(s), which can be an organic or inorganic based polymer or blend of polymers, typically at least one pigment, can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. The term “enhanced self-priming topcoat”, also referred to as an “enhanced direct to substrate coating” refers to a mixture of functionalized fluorinated binders, such as a fluoroethylene-alkyl vinyl ether in whole or in part with other binder(s), which can be an organic or inorganic based polymer or blend of polymers, typically at least one pigment, can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. Examples of self-priming topcoats include those that conform to TT-P-2756A. Examples of self-priming topcoats include those available from PPG (03W169 and 03GY369), and examples of enhanced self-priming topcoats include Defthane® ELT™/ESPT and product code number 97GY121, available from PPG. However, other self-priming topcoats and enhanced self-priming topcoats can be used in the coating system according to the present invention as will be understood by those of skill in the art with reference to this disclosure.
According to the present invention, the self-priming topcoat and enhanced self-priming topcoat may be applied directly to the sealed substrate. The self-priming topcoat and enhanced self-priming topcoat can optionally be applied to an organic or inorganic polymeric coating, such as a primer or paint film. The self-priming topcoat layer and enhanced self-priming topcoat is typically the coating layer in a single or multi-layer coating system where the outer surface of the coating is exposed to the atmosphere or environment, and the inner surface of the coating is typically in contact with the substrate or optional polymer coating or primer.
According to the present invention, the topcoat, self-priming topcoat, and enhanced self-priming topcoat can be applied to the sealed substrate, in either a wet or “not fully cured” condition that dries or cures over time, that is, solvent evaporates and/or there is a chemical reaction. The coatings can dry or cure either naturally or by accelerated means for example, an ultraviolet light cured system to form a film or “cured” paint. The coatings can also be applied in a semi or fully cured state, such as an adhesive.
In addition, a colorant and, if desired, various additives such as surfactants, wetting agents or catalyst can be included in the coating composition (electrodepositable, powder, or liquid). As used herein, the term “colorant” means any substance that imparts color and/or other opacity and/or other visual effect to the composition. Example colorants include pigments, dyes and tints, such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA), as well as special effect compositions.
In general, the colorant can be present in the coating composition in any amount sufficient to impart the desired visual and/or color effect. The colorant may comprise from 1 to 65 weight percent, such as from 3 to 40 weight percent or 5 to 35 weight percent, with weight percent based on the total weight of the composition.
For purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be read as if prefaced by the word “about,” even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open-ended numerical range is described herein, all numbers, values, amounts, percentages, subranges and fractions within or encompassed by the numerical range are to be considered as being specifically included in and belonging to the original disclosure of this application as if these numbers, values, amounts, percentages, subranges and fractions had been explicitly written out in their entirety.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.
As used herein, unless indicated otherwise, a plural term can encompass its singular counterpart and vice versa, unless indicated otherwise. For example, although reference is made herein to “a” first composition, “a” second composition, and “an” oxidizing agent, a combination (i.e., a plurality) of these components can be used. In addition, in this application, the use of “or” means “and/or” unless specifically stated otherwise, even though “and/or” may be explicitly used in certain instances.
As used herein, “including,” “containing” and like terms are understood in the context of this application to be synonymous with “comprising” and are therefore open-ended and do not exclude the presence of additional undescribed and/or unrecited elements, materials, ingredients and/or method steps. As used herein, “consisting of” is understood in the context of this application to exclude the presence of any unspecified element, ingredient and/or method step. As used herein, “consisting essentially of” is understood in the context of this application to include the specified elements, materials, ingredients and/or method steps “and those that do not materially affect the basic and novel characteristic(s)” of what is being described.
Unless otherwise disclosed herein, the term “substantially free,” when used with respect to the absence of a particular material, means that such material, if present at all in a composition, a bath containing the composition, and/or layers formed from and comprising the composition, only is present in a trace amount of 5 ppm or less based on a total weight of the composition or layer(s), as the case may be, excluding any amount of such material that may be present or derived as a result of drag-in, substrate(s), and/or dissolution of equipment). Unless otherwise disclosed herein, the term “essentially free,” when used with respect to the absence of a particular material, means that such material, if present at all in a composition, a bath containing the composition, and/or layers formed from and comprising the composition, only is present in a trace amount of 1 ppm or less based on a total weight of the composition or layer(s), as the case may be. Unless otherwise disclosed herein, the term “completely free,” when used with respect to the absence of a particular material, means that such material, if present at all in a composition, a bath containing the composition, and/or layers formed from and comprising the composition, is absent from the composition, the bath containing the composition, and/or layers formed from and comprising same (i.e., the composition, bath containing the composition, and/or layers formed from and comprising the composition contain 0 ppm of such material).
As used herein, the terms “on,” “onto,” “applied on,” “applied onto,” “formed on,” “deposited on,” “deposited onto,” mean formed, overlaid, deposited, and/or provided on but not necessarily in contact with the surface. For example, a coating layer “formed over” a substrate does not preclude the presence of one or more other intervening coating layers of the same or different composition located between the formed coating layer and the substrate.
As used herein, a “salt” refers to an ionic compound made up of metal cations and non-metallic anions and having an overall electrical charge of zero. Salts may be hydrated or anhydrous.
As used herein, “aqueous composition” refers to solution or dispersion in a medium that comprises predominantly water. For example, the aqueous medium may comprise water in an amount of more than 50 wt. %, or more than 70 wt. % or more than 80 wt. % or more than 90 wt. % or more than 95 wt. %, based on the total weight of the medium. The aqueous medium may for example consist substantially of water.
As used herein, “conversion composition” refers to a composition that is capable of reacting with and chemically altering the substrate surface and binding to it to form a film that affords corrosion protection.
As used herein, “conversion bath” refers to an aqueous bath containing the conversion composition and that may contain components that are byproducts of the process of contacting a substrate with the conversion composition.
As used herein, the term “first composition metal cation(s)” refers to metal cations of a lanthanide series element, a Group IIA metal, a Group IIIB metal, a Group IVB metal, a Group VB metal, a Group VIB metal, a Group VIM metal, and/or a Group XII metal.
As used herein, a “sealing composition” refers to a composition, e.g. a solution or dispersion, that affects a substrate surface or a material deposited onto a substrate surface in such a way as to alter the physical and/or chemical properties of the substrate surface (i.e., the composition affords corrosion protection).
As used herein, the term “Group IA metal” refers to an element that is in Group IA of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63rd edition (1983), corresponding to Group 1 in the actual IUPAC numbering.
As used herein, the term “Group IA metal compound” refers to compounds that include at least one element that is in Group IA of the CAS version of the Periodic Table of the Elements.
As used herein, the term “Group IIIB metal” refers to yttrium and scandium of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63rd edition (1983), corresponding to Group 3 in the actual IUPAC numbering. For clarity, “Group IIIB metal” expressly excludes lanthanide series elements.
As used herein, the term “Group IIIB metal compound” refers to compounds that include at least one element that is in group IIIB of the CAS version of the Periodic Table of the Elements as defined above.
As used herein, the term “Group IVB metal” refers to an element that is in group IVB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63rd edition (1983), corresponding to Group 4 in the actual IUPAC numbering.
As used herein, the term “Group IVB metal compound” refers to compounds that include at least one element that is in Group IVB of the CAS version of the Periodic Table of the Elements.
As used herein, the term “Group VB metal” refers to an element that is in group VB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63rd edition (1983), corresponding to Group 5 in the actual IUPAC numbering.
As used herein, the term “Group VB metal compound” refers to compounds that include at least one element that is in Group VB of the CAS version of the Periodic Table of the Elements.
As used herein, the term “Group VIB metal” refers to an element that is in group VIB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63rd edition (1983), corresponding to Group 6 in the actual IUPAC numbering.
As used herein, the term “Group VIB metal compound” refers to compounds that include at least one element that is in Group VIB of the CAS version of the Periodic Table of the Elements.
As used herein, the term “lanthanide series elements” refers to elements 57-71 of the CAS version of the Periodic Table of the Elements and includes elemental versions of the lanthanide series elements. In embodiments, the lanthanide series elements may be those which have both common oxidation states of +3 and +4, referred to hereinafter as +3/+4 oxidation states.
As used herein, the term “lanthanide compound” refers to compounds that include at least one of elements 57-71 of the CAS version of the Periodic Table of the Elements.
As used herein, the term “halogen” refers to any of the elements fluorine, chlorine, bromine, iodine, and astatine of the CAS version of the Periodic Table of the Elements, corresponding to Group VIIA of the periodic table.
As used herein, the term “halide” refers to compounds that include at least one halogen.
As used herein, the term “aluminum,” when used in reference to a substrate, refers to substrates made of or comprising aluminum and/or aluminum alloy, and clad aluminum substrates.
As used herein, the term “oxidizing agent,” when used with respect to a component of the conversion composition, refers to a chemical which is capable of oxidizing at least one of: a metal present in the substrate which is contacted by the conversion composition, a lanthanide series element present in the conversion composition, and/or a metal-complexing agent present in the conversion composition. As used herein with respect to “oxidizing agent,” the phrase “capable of oxidizing” means capable of removing electrons from an atom or a molecule present in the substrate or the conversion composition, as the case may be, thereby decreasing the number of electrons of such atom or molecule.
Unless otherwise disclosed herein, as used herein, the terms “total composition weight”, “total weight of a composition” or similar terms refer to the total weight of all ingredients being present in the respective composition including any carriers and solvents.
In view of the foregoing description the present invention thus relates in particular, without being limited thereto, to the following Aspects 1-29:
1. A system for treating a substrate comprising: a first composition for contacting at least a portion of the substrate, the first composition comprising a lanthanide series element cation and an oxidizing agent
2. The system of Aspect 1, wherein the oxidizing agent is present in the first composition in an amount of 25 ppm to 25,000 ppm based on total weight of the first composition.
3. The system of Aspect 1 or 2, wherein the lanthanide series element cation comprises cerium, praseodymium, or combinations thereof.
4. The system of any of the preceding Aspects, wherein the lanthanide series element cation is present in the first composition in an amount of 50 ppm to 200 ppm (calculated as cation) based on total weight of the first conversion composition.
5. The system of any of the preceding Aspects, further comprising a second composition for treating at least a portion of the substrate, the second composition comprising a Group IA metal cation.
6. The system of Aspect 5, wherein the Group IA metal cation comprises lithium, sodium, potassium, or combinations thereof.
7. The system of Aspect 5 or 6, wherein the Group IA metal cation is present in the second composition in an amount of 5 ppm to 30,000 ppm (as metal cation) based on a total weight of the second composition.
8. The system of any of Aspects 5 to 7, wherein the second composition has a pH of 8 to 13.
9. The system of any of Aspects 1 to 4, further comprising a third composition for treating at least a portion of the substrate, the second composition comprising a Group IVB metal cation.
10. The system of Aspect 9, wherein the Group IVB metal cation comprises zirconium, titanium, or combinations thereof.
11. The system of Aspect 9 or 10, wherein the Group IVB metal cation is present in the third composition in an amount of 110 ppm to 170 ppm (as metal cation) based on a total weight of the third composition.
12. The system of any of Aspects 9 to 11, wherein the third composition has a pH of 4 to 5.
13. The system of any of Aspects 9-12, wherein the third composition further comprises an amino compound.
14. The system of any of the preceding Aspects, wherein the system is substantially free of phosphate.
15. A substrate treated with the system of any of the preceding Aspects.
16. The substrate of Aspect 15, wherein the substrate treated with the system has at least a 5% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising zirconium as measured by CASS testing.
17. The substrate of Aspect 15 or Aspect 16, wherein at least a portion of the substrate surface is sanded, and wherein the substrate treated with the system has at least a 55% decrease in scribe creep on the sanded substrate surface compared to a sanded substrate treated with a composition comprising zirconium as measured by filiform corrosion testing.
18. The substrate of any of Aspect 15 to 17, wherein at least a portion of the substrate surface is sanded, and wherein the substrate treated with the system has at least a 78% decrease in scribe creep on the sanded substrate surface compared to a sanded substrate treated with a composition comprising zirconium as measured by ASTM G85 A2 corrosion testing.
19. A substrate treated with the system of Aspect 5.
20. The substrate of Aspect 19, wherein the substrate treated with the system has at least a 25% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising zirconium as measured by ASTM G85 A2 testing.
21. The substrate treated with the system of Aspect 9.
22. The substrate of Aspect 21, wherein the substrate treated with the system has at least one of the following: a 13% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising a lanthanide series element cation or a Group IVB metal cation but not both as measured by CASS testing; a 47% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising a lanthanide series element cation or a Group IVB metal cation but not both as measured by SAE J2635; and/or at least a 42% increase in crosshatch adhesion compared to a substrate treated with a composition comprising a lanthanide series element cation or a Group IVB metal cation but not both.
23. A method of treating a substrate comprising: contacting at least a portion of the substrate surface with a first composition comprising a lanthanide series element cation and an oxidizing agent.
24. The method of Aspect 23, wherein the substrate surface is contacted with the first composition to result in a level of the lanthanide series element cation on the contacted substrate surface of at least 100 counts greater than on a surface of a substrate that is not contacted with the first composition as measured by X-ray fluorescence (measured using X-Met 7500, Oxford Instruments; operating parameters 60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.5 μs).
25. The method of Aspect 23 or 24, further comprising contacting at least a portion of the substrate surface with a second composition comprising a Group IA metal cation and/or a Group IVB metal cation.
26. The method of any of Aspects 23 to 25, wherein the contacting with the first composition occurs prior to the contacting with the second composition.
27. The method of any of Aspects 23 to 25, wherein the contacting with the second composition occurs prior to the contacting with the first composition.
28. The method of any of Aspects 23 to 27, wherein the contacting with the first composition is 15 seconds to 4 minutes.
29. The method of any of Aspects 23 to 28, further comprising heating the substrate for 15 minutes to 30 minutes at a temperature of 110° C. to 232° C.
30. A substrate treated according to the method of Aspect 29, wherein the substrate has a b* value of less than 3.09 (spectral component excluded, 25 mm aperture).
Whereas particular features of the present invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the coating composition, coating, and methods disclosed herein may be made without departing from the scope in the appended claims.
Illustrating the invention are the following examples that are not to be considered as limiting the invention to their details. All parts and percentages in the examples, as well as throughout the specification, are by weight unless otherwise indicated.
A cleaner bath was prepared at 1.25% v/v concentration of Chemkleen 2010LP (a phosphate-free alkaline cleaner available from PPG) and 0.125% of Chemkleen 181 ALP (a phosphate-free blended surfactant additive, available from PPG). For spray cleaning, a 10 gallon bath was prepared. The bath was made up with deionized water. The temperature of the bath was 120° F. and when panels were run through the cleaner it was utilized for 2 minutes. The pressure of the spray cleaning was that of 10-15 psi with the utilization of a series of “vee jet” spray nozzles.
A five gallon vessel was filled approximately three-fourths full with deionized water. To this was added 700 ml of Chemfos 700A, 1.5 ml Chemfos FE, 51 ml Chemfos AFL, and 375m1s of Chemfos 700B (all available from PPG). To this was added 28.6 g zinc nitrate hexahydrate and 2.5 grams of Sodium Nitrite (both available from Fischer Scientific). The free acid of the bath was operated at 0.7-0.8 points of free acid, 15-19 points of total acid, and 2.2-2.7 gas points of nitrite. Free acid and total acid were measured as follows:
Equipment:
Reagents:
Procedure for Free Acid Titration:
Procedure for Total Acid Titration:
The amount of nitrite in solution was measured using a fermentation tube using the protocol described in the technical data sheet for Chemfos Liquid Additive (PPG Industries, Inc., Cleveland, Ohio). A fermentation tube was filled with a 70 mL sample of the pretreatment bath to just below the mouth of the tube. Approximately 2.0 g of sulfamic acid was added to the tube, and the tube was inverted to mix the sulfamic acid and pretreatment solution. Gas evolution occurred, which displaced the liquid in the top of the fermentation tube, and the level was read and recorded. The level corresponded to the gas points measured in the solution in milliliters.
To adjust to obtain the correct amounts of free and total acid, CF700 B was utilized to adjust according to product data sheet. The temperature of the bath was 125° F. and when panels were run through the bath it was utilized for 2 minutes.
1.1 g/L of Versabond RC (also known as RC30, commercially available from PPG Industries, Inc.) was added to a filled 5 gallon (18.79 liters) vessel of deionized water to be utilized immediately prior to the use of the zinc phosphate bath described above. The temperature of the bath was 80° F. and when panels were run through the bath it was utilized for 1 minute.
Zircobond 1.5 (a zirconium-containing pretreatment composition commercially available from PPG Industries, Inc.) was added to 5 gallons of deionized water according to manufacturer's instructions to yield a composition containing 175 ppm of zirconium.
The resultant solution had a pH of 4.72, measured using a Thermo Scientific Orion Dual Star pH/ISE Bench Top Reader attached to an Accumet Cat #13-620-221 pH probe. The temperature of the bath was 80° F. and when panels were run through the bath it was utilized for 2 minutes.
Zircobond 2.0 (a zirconium-containing pretreatment composition commercially available from PPG Industries, Inc.) was added to 5 gallons of deionized water according to manufacturer's instructions to yield a composition containing 175 ppm of zirconium, 5 ppm lithium, and 40 ppm Mo.
The resultant solution had a pH of 4.72. The temperature of the bath was 80° F. and when panels were run through the bath it was utilized for 2 minutes.
To a 2 liter vessel of deionized water was added 3 Grams Cerium (III) Chloride Heptahydrate (Available from Acros Organics) and 5 Grams 29-32% Hydrogen Peroxide (Available from Alfa Aesar). The temperature of the bath was ambient, and the bath was still when the panel was immersed (i.e., not stirred or agitated). When the panels were run through the bath it was utilized for 2 minutes.
Aluminum Panel Preparation: X610 (ACT Test Panels LLC, Hillsdale, Mich.) were cut in half to make panel size 4″×6″. The bottom 3 inches of each panel was sanded with P320 grit paper available from 3M which was utilized on a 6″ random orbital palm sander available from ATD (Advanced Tool Design Model-ATD-2088). The sanding was utilized to help determine any corrosion performance that may have been on sanded and unsanded parts of the metal. Sanding is used in the field as a means to increase the adhesion of subsequent paint surfaces.
For each run, two half sanded X610 Aluminum panels (cut to 4″×6″ from ACT Test Panels, LLC) were first cleaned as follows: All testing panels were spray cleaned in a stainless steel spray cabinet using Vee-jet nozzles at 10 to 15 psi, using the standard Chemkleen 2010LP/181ALP bath detailed above for two minutes at 49° C., followed by immersion rinse in DI water for 15 seconds and spray rinse with DI water for 15 seconds.
Panels were then introduced into one of the pretreatment baths described above as follows:
Set 1—Panels were immersed in the Rinse Conditioner Bath 1 minute and then immediately were immersed in Pretreatment Bath 1 for 2 minutes.
Set 2—Panels were immersed in Pretreatment Bath 2 for 2 minutes.
Set 3—Panels were immersed in Pretreatment Bath 3 for 2 minutes.
Set 4—Panels were immersed in Pretreatment Bath 4 for 2 minutes.
Following immersion in one of the Pretreatment Baths, all panels then were spray rinsed with DI water for 20-30 seconds. Panels were warm air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until the panel was dry (about 1-5 minutes).
After drying, the panels were electrocoated with ED7000Z electrocoat, available from PPG. The electrocoat was applied to target a 0.60 mil thickness. The rectifier (Xantrex Model XFR600-2) was set to the “Coulomb Controlled” setting. The conditions were set with 23 coulombs for Zinc Phosphate and 24 Coulombs for Zirconium and Experimental Ce Chloride Pretreatment, 0.5 amp limit, voltage set point of 220 V for Zinc Phosphate and 180V for Zirconium and Experimental Ce Chloride Pretreatment, and a ramp time of 30s. The electrocoat was maintained at 90° F., with a stir speed of 340 rpms. After the electrocoat was applied, the panels were baked in an oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes. The coating thickness was measured using a film thickness gauge (Fischer Technology Inc. Model FMP40C).
Panels were evaluated for a yellowing of the electrocoat layer by visual inspection by the naked eye. Panels also were tested for scribe creep blistering using the ASTM-B 368-09 Copper Acetic Acid Salt Spray, to measure scribe creep. Scribe creep was measured from affected paint to affected paint to the left and right of the scribe. The scribe was placed into the panel prior to being placed into the cabinet for a length of 20 Days or 480 Hours.
The scribe was measured according to the following protocol: the scribe length was 4 Inches/10.16 cm. A reading of affected paint to affected paint was measured at each cm along the scribe creating a total of 10 points of measurement. From this the average of the two panels led to average scribe creep reported in Table 1 below. The measurements were made by the use of a Fowler Sylvac digital caliper Model S 235.
The table below provides Scribe Creep Measurements from the panels tested as described above.
The data in Table 1 demonstrate that an electrocoated panel pretreated with a pretreatment composition comprising cerium results in a 5% reduction in the scribe creep following 480 hours exposure to copper acetic salt spray (ASTM-B 368-09) compared to an electrocoated panel pretreated with a zirconium/molybdenum/lithium-containing pretreatment. Notably, an electrocoated panel treated with a zirconium-containing pretreatment composition is visibly yellow to the naked eye, while an electrocoated panel treated with a lanthanide-containing pretreatment composition is not visibly yellow to the naked eye.
The data in Table 1 also demonstrate that an electrocoated panel pretreated with a pretreatment composition comprising cerium results in a 27% reduction in the scribe creep following 480 hours exposure to copper acetic salt spray (ASTM-B 368-09) compared to an electrocoated panel pretreated with a zirconium-containing pretreatment.
The data shown in Table 1 also demonstrate that an electrocoated panel pretreated with a pretreatment composition comprising cerium results in a 65% reduction in the scribe creep following 480 hours exposure to copper acetic salt spray (ASTM-B 368-09) compared to an electrocoated panel pretreated with a zinc phosphate pretreatment.
Aluminum 6111 panels (from ACT Test Panels, LLC) were cut to 4″×6″ sample size. The bottom 3″ of the panels were sanded with P320 grit silicon carbide paper (available from 3M) on a 6″ random orbital palm sander (Advanced Tool Design Model-ATD-2088). Half-sanding the panel surface served to determine any corrosion performance difference between as-milled (unsanded) and sanded substrates. Surface sanding or abrasion is conducted in the field to promote adhesion of subsequent paint applications.
Each of the half-sanded 6111 aluminum panels were spray cleaned with standard Chemkleen 2010LP/181ALP bath (composed of 1.25 vol. % of Chemkleen 2010LP (a phosphate-free alkaline cleaner available from PPG Industries, Inc.) and 0.125 vol. % of Chemkleen 181 ALP (a phosphate-free blended surfactant additive, available from PPG Industries, Inc.) in deionized water) in a stainless steel spray tank using vee-jet nozzles at 10 to 15 psi, for two minutes at 120° F. This was followed by immersion rinse in DI water for 15 seconds, and final spray rinse with DI water for 15 seconds.
Immediately after spray rinsing, the cleaned panels were introduced to the pretreatment baths.
The first set of panels were pretreated with Zircobond 1.5, a zirconium-containing pretreatment composition commercially available from PPG Industries, Inc. A 5-gallon bath was prepared as per manufacturer's instruction to yield a pH of 4.72, a zirconium concentration of 200 ppm, and a free fluoride concentration of 101 ppm. The panels were pretreated by immersion into the pretreatment bath at 80° F. with low agitation, for 2 minutes.
The second set of panels were pretreated with a cerium chloride pretreatment composition. The cerium chloride pretreatment bath was composed of 0.15 wt. % of cerium (III) chloride heptahydrate (available from Acros Organics) and 0.25 wt. % of a 29 to 32% solution of hydrogen peroxide (available from Alfa Aesar) in deionized water. The panels were pretreated by immersion into a 3 gallon pretreatment bath at ambient temperature without any agitation for 2 minutes.
Upon removal from the pretreatment baths, the pretreated panels were spray rinsed with DI water for 20 to 30 seconds. Panels were air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until fully dry (about 3 to 5 minutes).
The pretreated panels were electrocoated with cationic ED6280Z paint (available from PPG) using a direct current rectifier (Xantrex Model XFR600-2). A coating dry film thickness of 0.8 mil was achieved by passing a 24.5 C or 20.0 C charge for the zirconium and cerium pretreatments, respectively, at a current limit of 0.5 A, and an applied electrical potential of 220 V after a 30 second ramp time. The ED6280Z paint bath was maintained at 90° F. with a stir rate of 340 rpm. The electrocoated panels were spray rinsed with DI water. The panels were baked in an electric oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes. The coating thickness was measured using a Permascope (Fischer Technology Inc. Model FMP40C).
Two corrosion test methods were utilized to evaluate the corrosion performance of the panels: ASTM G85 A2 Cyclic Acidified Salt Fog Testing for 3 weeks, and a filiform corrosion for 6 weeks. For the latter test, the panels were placed horizontally in a desicator containing a thin layer of 12 N hydrochloric acid (HCl) for 1 hour at ambient temperature, such that only the HCl fumes came into contact with the sample, within 5 minutes, the panels were placed in a vertical orientation in the humidity cabinet maintained at 40 C and 80% relative humidity for 6 weeks. Duplicate panels were included for each testing. Prior to corrosion testing, the panels were scribed with an X-configuration. The scribe was positioned with the top legs on the as-milled surface and the bottom legs on the sanded surface. Each leg is 40 mm long.
Corrosion damage is measured as the perpendicular distance from the scribe to tip of the filament or blister. Each panel provided two sets of five measurements: a set from the top legs for the as-milled surface, and another set from the bottom legs for the sanded surface. Measurements were taken from the five longest corrosion sites. The average corrosion damage was calculated based on a total of ten measurements from duplicate panels. All readings were measured using a Fowler Sylvac digital caliper Model S 235.
The average corrosion damage is reported in Table 1.1 below. Relative to the control zirconium pretreatment, the cerium chloride pretreated panels displayed better corrosion performance on sanded and unsanded 6111 aluminum alloys.
Aluminum 6111 panels (from ACT Test Panels, LLC) were cut to 4″×6″ sample size. The bottom 3″ of the panels were sanded with P320 grit silicon carbide paper (available from 3M) on a 6″ random orbital palm sander (Advanced Tool Design Model-ATD-2088). Half-sanding the panel surface served to determine any corrosion performance difference between as-milled (unsanded) and sanded substrates. Surface sanding or abrasion is conducted in the field to promote adhesion of subsequent paint applications.
Each of the half-sanded 6111 aluminum panels were spray cleaned with standard Chemkleen 2010LP/181ALP bath (composed of 1.25 vol. % of Chemkleen 2010LP (a phosphate-free alkaline cleaner available from PPG Industries, Inc.) and 0.125 vol. % of Chemkleen 181 ALP (a phosphate-free blended surfactant additive, available from PPG Industries, Inc.) in deionized water in a stainless steel spray tank using vee-jet nozzles at 10 to 15 psi, for two minutes at 120° F. This was followed by immersion rinse in DI water for 15 seconds, and final spray rinse with DI water for 15 seconds.
Immediately after spray rinsing, the cleaned panels were introduced to the pretreatment baths.
The first set of panels were pretreated with Zircobond 1.5, a zirconium-containing pretreatment composition commercially available from PPG Industries, Inc. A 5-gallon bath was prepared according to manufacturer's instruction to yield a pH of 4.72, a zirconium concentration of 200 ppm, and a free fluoride concentration of 101 ppm. The panels were pretreated by immersion into the pretreatment bath at 80° F. with low agitation, for 2 minutes. The panels were spray rinsed with DI water for 20 to 30 seconds, and air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until fully dry (about 3 to 5 minutes).
The second through fifth sets of panels were pretreated with a two-step pretreatment process wherein the panel is pretreated with two separate pretreatment compositions prepared as three-gallon baths with the compositions as described below.
The cerium chloride pretreatment bath was composed of 0.15 wt. % of cerium (III) chloride heptahydrate (available from Acros Organics) and 0.25 wt. % of hydrogen peroxide, 29 to 32% solution, (available from Alfa Aesar) in deionized water.
The lithium hydroxide pretreatment bath was composed of 0.17 wt. % of lithium hydroxide monohydrate (available from Acros Organics) in deionized water.
The lithium carbonate pretreatment bath was composed of 0.15 wt. % of lithium carbonate (available from Acros Organics) in deionized water.
The second set of panels were treated with a cerium chloride/lithium hydroxide two-step pretreatment process. The panels were first pretreated by immersion into the cerium chloride pretreatment composition at ambient temperature for 2 minutes, without agitation. The panels were spray rinsed with DI water, followed by full immersion pretreatment in the lithium hydroxide pretreatment composition for 1 minute at ambient temperature. The panels were air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until fully dry (about 3 to 5 minutes).
The third set of panels were treated with a cerium chloride/lithium carbonate two-step pretreatment process. The panels were first pretreated by immersion into the cerium chloride pretreatment composition at ambient temperature for 2 minutes, without agitation. The panels were spray rinsed with DI water, followed by full immersion pretreatment in the lithium carbonate pretreatment for 1 minute at ambient temperature. The panels were air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until fully dry (about 3 to 5 minutes).
The fourth set of panels were pretreated with a lithium hydroxide/cerium chloride two-step pretreatment process. The panels were first pretreated by immersion into the lithium hydroxide pretreatment composition at ambient temperature for 1 minute, and directly followed by immersion into the cerium chloride pretreatment composition for 2 minutes. The panels were spray rinsed with DI water for 20 to 30 seconds, and air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until fully dry (about 3 to 5 minutes).
The fifth set of panels were pretreated with a lithium carbonate/cerium chloride two-step pretreatment process. The panels were first pretreated by immersion into the lithium carbonate pretreatment composition at ambient temperature for 1 minute, and directly followed by immersion into the cerium chloride pretreatment composition for 2 minutes. The panels were spray rinsed with DI water for 20 to 30 seconds, and air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until fully dry (about 3 to 5 minutes).
The pretreated panels were electrocoated with cationic ED6280Z paint (available from PPG) using a direct current rectifier (Xantrex Model XFR600-2). A coating dry film thickness of 0.8 mil was achieved with the coat out parameters listed in Table 2.2. The ED6280Z paint bath was maintained at 90° F., with a stir rate of 340 rpm. The electrocoated panels were spray rinsed with DI water. The panels were baked in an electric oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes. The coating thickness was measured using a Permascope (Fischer Technology Inc. Model FMP40C).
Two corrosion test methods were utilized to evaluate the corrosion performance of the panels: ASTM G85 A2 Cyclic Acidified Salt Fog Testing for 3 weeks, and a filiform corrosion for 6 weeks. For the latter test, the panels were placed horizontally in a desicator containing a thin layer of 12 N hydrochloric acid (HCl) for 1 hour at ambient temperature, such that only the HCl fumes came into contact with the sample, within 5 minutes, the panels were placed in a vertical orientation in the humidity cabinet maintained at 40 C and 80% relative humidity for 6 weeks. Duplicate panels were included for each testing. Prior to corrosion testing, the panels were scribed with an X-configuration. The scribe was positioned with the top legs on the as-milled surface and the bottom legs on the sanded surface. Each leg is 40 mm long.
Corrosion damage is measured as the perpendicular distance from the scribe to tip of the filament or blister. Each panel provided two sets of five measurements: a set from the top legs for the as-milled surface, and another set from the bottom legs for the sanded surface. Measurements were taken from the five longest corrosion sites. The average corrosion damage was calculated based on a total of ten measurements from duplicate panels. All readings were measured using a Fowler Sylvac digital caliper Model S 235.
The average corrosion damage is tabulated in Table 2.3. Relative to the control Zirconium pretreatment, all the experimental two-step pretreatments displayed better corrosion performance on sanded 6111 aluminum alloys.
Standard ChemKleen 2010LP/181ALP Cleaner: The cleaner bath was prepared at 1.25% v/v concentration of Chemkleen 2010LP (a phosphate-free alkaline cleaner available from PPG) and 0.125% of Chemkleen 181 ALP (a phosphate-free blended surfactant additive, available from PPG) in deionized water. For spray cleaning, a 10-gallon bath was prepared. Temperature of the bath was 120° F. and when panels were run through the cleaner it was utilized for 2 minutes. The pressure of the spray cleaning was 10 psi to 15 psi.
Control Zircobond 1.5 (ZB-1.5, commercially available zirconium pretreatment composition): To 5 gallons of deionized water was added 16.73 grams 45% hexafluorozirconic acid (available from Honeywell International Inc.), 30.02 grams of a 2% by weight copper solution (prepared by dissolving copper nitrate hemipentahydrate, available from Fisher Scientific, in deionized water), 15.4 grams of Chemfos AFL (available from PPG), and 29.8 grams of Chemfil Buffer (available from PPG). The resultant solution had a pH of 4.68 and 103 ppm of free fluoride.
Cerium Chloride Pretreatment Composition: To a 2 liter vessel of deionized water was added 3 Grams Cerium (III) Chloride Heptahydrate (Available from Acros Organics) and 5 Grams 29-32% Hydrogen Peroxide (Available from Alfa Aesar).
Test Panel Preparation
Set A panels were Zinc Hot Dipped Galvanized Unexposed (70G70UHDG) substrates pretreated with Chemfos®700 Zinc Phosphate Pretreatment, purchased from ACT Test Panels (Item No. 40085).
Zinc Hot Dipped Galvanized Exposed (HD60G60E) Item No. 53170 from ACT Test Panels were cut in half to make panel size 4″×6″.
For each run, two Zinc Hot Dipped Galvanized Exposed (cut to 4″×6″ from ACT Test Panels, LLC) were first cleaned as follows: The panels were spray cleaned in a stainless-steel spray cabinet using the standard Chemkleen 2010LP/181ALP bath described above for two minutes at a bath temperature of 49° C. at 10-15 psi spray pressure using a series of “vee jet” spray nozzles, followed by immersion rinse in DI water for 15 seconds and spray rinse with DI water for 15 seconds.
The cleaned panels were then immersed into one of the two pretreatment compositions described above:
Set B: Panels were immersed in the Zircobond 1.5 (ZB-1.5) pretreatment bath for 2 minutes at a bath temperature of 80° F.
Set C: Panels were immersed in the Cerium Chloride Pretreatment bath for 1 minute at ambient temperature.
All panels from set B and C were then spray rinsed with DI water for 20-30 seconds. Panels were warm air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until the panel was dry (about 1-5 minutes).
All panels from Set A, B and C were electrocoated with ED7000Z electrocoat, available from PPG. The electrocoat was applied to target of 0.60 mil thickness. The rectifier (Xantrex Model XFR600-2) was set to the “Coulomb Controlled” setting. The conditions were set with 23 coulombs for Set A (zinc phosphate pretreatment) and 24 Coulombs for Set B (zirconium pretreatment) and Set C (cerium chloride pretreatment), 0.5 amp limit, voltage set point of 220 V for Set A and 180V for Set B and Set C, and a ramp time of 30 seconds. The electrocoat was maintained at 90° F., with a stir speed of 340 rpms. After the electrocoat was applied, the panels were baked in an oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes. The coating thickness was measured using a film thickness gauge (Fischer Technology Inc. Model FMP40C).
The coated panels were tested for scribe creep blistering using the GMW 14872 Cyclic Corrosion testing method. Scribe creep is measured from affected paint to affected paint to the left and right of the scribe. The scribe is placed into the panel prior to being placed into the cabinet for a length of 40 cycles.
Two testing panels were evaluated to obtain the average scribe creep. The length of scribe was 4 inches (10.16 cm). A reading of affected paint to affected paint was measured at each centimeter along the scribe creating a total of 10 points of measurement for each panel. The measurements were taken by the use of a Fowler Sylvac digital caliper Model S 235. The average scribe creep of each panel was the average scribe creep for the 10 measurements. From this, the average of the average scribe creep of each of the two panels led to the average scribe creep for each set noted below in Table 3.1.
The data in Table 3.1 demonstrate at least a 21% decrease in average scribe creep on panels treated with the system of the present invention (i.e., cerium pretreatment composition) compared to panels treated with a zinc phosphate pretreatment composition or a zirconium pretreatment composition as measured by GMW 14872 Cyclic Corrosion testing.
Standard Ultrax 14AWS Cleaner: The bath was prepared at 1.25% v/v concentration of Ultrax 14 (a mild alkaline cleaner blended with surfactants available from PPG) in deionized water.
AMC66AW Deoxidizer: The bath was prepared with 2% v/v concentration of AMC66 (an acidic deoxidizer free of nitric acid available from PPG). Panels were run through the bath at 120° F. for 1 min.
Control X-Bond (commercially available zirconium pretreatment composition): To 5 gallons of deionized water was added 24.13 grams 45% hexafluorozirconic acid (available from Honeywell International Inc.), 16 grams of Chemfos AFL (available from PPG), and 33 grams of Chemfil Buffer (available from PPG). The resultant solution had a pH of 4.63 and 91.2 ppm of free fluoride.
Standard Chemseal 59: In a 1 gallon sleeve, 1% v/v Chemseal 59 (acidic sealer available from PPG) was prepared at pH=4.2.
Cerium Chloride (experimental pretreatment composition): To a 2 liter vessel of deionized water was added 3 grams cerium (III) chloride heptahydrate (available from Acros Organics) and 6 grams 29-32% hydrogen peroxide (available from Alfa Aesar).
Aluminum alloy 6061 panels (ACT Test Panels, LLC) were cut in half to make panel size 4″×6″. For each set, two 6061 aluminum panels were first cleaned as follows: All testing panels were spray cleaned in a stainless steel spray cabinet using Vee-jet nozzles at 10 to 15 psi, using a 10-gallon bath of the Standard Ultrax14AWS Cleaner described above for two minutes at a bath temperature of 49° C., followed by immersion rinse in DI water for 15 seconds and spray rinse with DI water for 15 seconds. Panels were then immersed in the AMC66AW Deoxidizer bath described above at a 49° C. bath temperature for 1 minute, followed by spray rinse with DI water for 15 seconds.
Panels were then introduced into the pretreatment baths detailed above.
Set 1: Panels were immersed in the X-Bond (XB) pretreatment bath for 2 minutes at a bath temperature of 80° F.
Set 2: Panels were immersed in the Cerium Chloride pretreatment bath for 2 minutes at ambient temperature.
Set 3: Panels were immersed in the Cerium Chloride pretreatment bath for 2 minutes at ambient temperature followed by immersion in the Chemseal 59 bath for 1 minute at ambient temperature.
All panels then were spray rinsed with DI water for 20-30 seconds. Panels were warm air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until the panel was dry (about 1-5 minutes).
After drying, the conversion coating was measured by X-ray fluorescence (X-Met 7500, Oxford Instruments; operating parameters 60 second timed assay, 15 kV, 45 μA, filter 3, T(p)=1.1 μs for lanthanides). Due to profile of the output, non-lanthanide conversion coatings do not have a baseline of zero counts and therefore, the difference between measured counts and baseline, not the absolute value of counts, was indicative of the coating's composition. The results are reported in Table 4.1.
Remaining panels were coated with powder coating Enviracryl® PCC10103 (acrylic coating available from PPG) to a thickness of 2.75 mil.
The coated panels were tested for scribe creep blistering using the ASTM-B 368-09 Copper Acetic Acid Salt Spray, to measure scribe creep. Scribe creep is measured from affected paint to affected paint to the left and right of the scribe. The scribe is placed into the panel prior to being placed into the cabinet for a length of 10 days or 240 hours. Below is a table of scribe creep measurements from the average of two testing panels, measured at seven points evenly spaced along a 4-inch scribe. The measurements were recorded using a Fowler Sylvac digital caliper Model S 235.
Panels were tested for filiform corrosion using SAE J2635 method. Scribe creep is measured from affected paint to affected paint to the left or to the right of the scribe. The scribe is placed into the panel prior to initiation and subsequently placed into a humidity cabinet for 28 days. Below is a table of scribe creep measurements from the average of two panels per set, measured at seven points evenly spaced along a 4-inch scribe.
Panels were subjected to crosshatch adhesion testing after 1 day soaking in a water bath heated to 60° C. Panels were allowed to recover for 20 minutes in ambient conditions. With a razor blade and a Gardco Temper II Gauge tool, eleven cuts spaced 1.5 mm apart were made perpendicular to another eleven cuts spaced 1.5 mm apart. Fibrous tape was adhered to the area and quickly pulled away. Paint adhesion was rated on a scale of 1 (no remaining paint adhesion) to 10 (perfect adhesion).
The data in Table 4.2 demonstrate at least a 13% decrease in scribe creep on panels treated with the system of the present invention compared to panels treated only with a cerium conversion composition or only a zirconium composition as measured by CASS testing. Furthermore, the data in Table 4.2 demonstrate at least a 47% decrease in scribe creep on panels treated with the system of the present invention (i.e., cerium conversion composition followed by zirconium-containing conversion composition) compared to panels treated only with a cerium conversion composition or only a zirconium composition as measured by SAE J2635 testing. Finally, the data in Table 4.2 demonstrate at least a 42% increase in crosshatch adhesion on panels treated with the system of the present invention (i.e., cerium conversion composition followed by zirconium-containing conversion composition) compared to panels treated only with a cerium conversion composition or only a zirconium composition.
Standard ChemKleen 2010LP/181ALP Cleaner: The bath was prepared at 1.25% v/v concentration of Chemkleen 2010LP (a phosphate-free alkaline cleaner available from PPG) and 0.125% of Chemkleen 181 ALP (a phosphate-free blended surfactant additive, available from PPG) in deionized water. For spray cleaning, a 10-gallon bath was prepared.
ChemDeox395: An acidic deoxidizer (pH 2.5) was prepared from a hexafluorosilicic acid, ammonium bifluoride, and sodium hydroxide.
Control Zircobond 1.5 (commercially available zirconium pretreatment composition): To 5 gallons of deionized water was added 19.16 grams 45% hexafluorozirconic acid (available from Honeywell International Inc.), 35.09 grams of a 2% by weight copper solution (prepared by dissolving copper nitrate hemipentahydrate, available from Fisher Scientific, in deionized water), 14 grams of Chemfos AFL (available from PPG), and 32 grams of Chemfil Buffer (available from PPG). The resultant solution had a pH of 4.61 and 91.2 ppm of free fluoride.
Standard Chemseal 59: In 1-gallon sleeve, 1% v/v Chemseal 59 (acidic sealer available from PPG) was prepared at pH=4.2.
Cerium Chloride Pretreatment Composition: To a 2-liter vessel of deionized water was added 3 grams cerium (III) chloride heptahydrate (available from Acros Organics) and 6 grams 29-32% hydrogen peroxide (available from Alfa Aesar).
Aluminum alloy 6061 panels (ACT Test Panels, LLC) were cut in half to make panel size 4″×6″. For each set, two 6061 aluminum panels were first cleaned as follows: All testing panels were spray cleaned in a stainless steel spray cabinet using Vee-jet nozzles at 10 to 15 psi, using the standard ChemKleen 2010LP/181ALP cleaner bath detailed above for two minutes at a bath temperature of 49° C., followed by immersion rinse in DI water for 15 seconds and spray rinse with DI water for 15 seconds. Panels were then immersed in ChemDeox395 at a bath temperature of 90° F. with high agitation for 1 min, followed by spray rinse with DI water for 15 seconds.
Panels were then introduced into the pretreatment baths detailed above:
Set 4: Panels were immersed in the Zircobond 1.5 pretreatment bath for 2 minutes at a bath temperature of 80° F.
Set 5: Panels were immersed in the cerium chloride pretreatment bath for 2 minutes at ambient temperature.
Set 6: Panels were immersed in the cerium chloride pretreatment bath for 2 minutes at ambient temperature followed by immersion in the Chemseal 59 bath for 1 minute at ambient temperature.
All pretreated panels then were spray rinsed with DI water for 20-30 seconds and warm air dried using a Hi-Velocity handheld blow-dryer made by Oster® (model number 078302-300-000) on high-setting at a temperature of about 50-55° C. until the panel was dry (about 1-5 minutes).
After drying, conversion coating was measured by X-ray fluorescence (X-Met 7500, Oxford Instruments; operating parameters 60 second timed assay, 15 kV, 45 μA, filter 3, T(p)=1.1 μs for lanthanides). Due to profile of the output, non-lanthanide conversion coatings do not have a baseline of zero counts and therefore, the difference between measured counts and baseline, not the absolute value of counts, was indicative of the coating's composition.
After drying, the panels were electrocoated with ED7000Z electrocoat, available from PPG. The electrocoat was applied to target a 0.60 mil thickness. The rectifier (Xantrex Model XFR600-2) was set to the “Coulomb Controlled” setting. The conditions were set with 22 Coulombs for Set 4 (zirconium) and 21 Coulombs for Set 5 (cerium chloride) and Set 6 (cerium chloride and seal), 0.5 amp limit, voltage set point of 200 V, and a ramp time of 30s. The electrocoat was maintained at a bath temperature of 90° F., with a stir speed of 320 rpm. After the electrocoat was applied, the panels were baked in an oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes. The coating thickness was measured using a film thickness gauge (Fischer Technology Inc. Model FMP40C).
The coated panels were tested for scribe creep blistering using the ASTM-B 368-09 Copper Acetic Acid Salt Spray, to measure scribe creep. Scribe creep is measured from affected paint to affected paint to the left and right of the scribe. The scribe is placed into the panel prior to being placed into the cabinet for a length of 20 days or 480 hours. Below is a table of scribe creep measurements from the average of two testing panels per set, measured at seven points evenly spaced along a 4-inch scribe. The measurements were recorded using a Fowler Sylvac digital caliper Model S 235.
Panels were tested for filiform corrosion for 6 weeks. Panels were placed horizontally in a desicator containing a thin layer of 12 N hydrochloric acid (HCl) for 1 hour at ambient temperature, such that only the HCl fumes came into contact with the sample, within 5 minutes, the panels were placed in a vertical orientation in the humidity cabinet maintained at 40 C and 80% relative humidity for 6 weeks. Scribe creep was measured from affected paint to affected paint to the left and right of the scribe. Below is a table of scribe creep measurements from the average of two testing panels per set, measured at seven points evenly spaced along a 4-inch scribe. The measurements were recorded using a Fowler Sylvac digital caliper Model S 235.
The data in Table 5.2 demonstrate at least a 39% decrease in scribe creep on electrocoated panels treated with the system of the present invention compared to panels treated only with a cerium conversion composition or only a zirconium composition as measured by CASS testing. Furthermore, the data in Table 5.2 demonstrate at least a 10% decrease in scribe creep on electrocoated panels treated with the system of the present invention compared to panels treated only with a cerium conversion composition or only a zirconium composition as measured by filiform corrosion testing.
To a 2 liter vessel of deionized water was added 3 Grams Cerium (III) Chloride Heptahydrate (Available from Acros Organics) and 5 Grams 29-32% Hydrogen Peroxide (Available from Alfa Aesar). The temperature of the bath was ambient, and the bath was still when the panel was immersed (i.e., not stirred or agitated).
In this example, 6111 aluminum panels (ACT) were evaluated for deposition of cerium or zinc phosphate and for coloration of the pretreated panels.
4″×12″ panels of 6111 Aluminum (available from ACT Test Panels, LLC, product no. 39279) were cut in half to make panels of 4″×6″.
For each set, one half 6111 Aluminum panel was cleaned by spray cleaning in a stainless steel spray cabinet using Vee-jet nozzles at 10 to 15 psi, using Cleaner 2 for two minutes at 120° F., followed by an immersion rinse in deionized water for 15 seconds and then a spray rinse with deionized water for 15 seconds using the Melnor Rear-Trigger 7-Pattern nozzle set to shower mode described above. Panels were then introduced into one of the conversion composition baths described above as follows:
Set 10—Panels were immersed in a bath containing Conversion Composition 4 (bath ambient) for 2 minutes. Panels then were spray rinsed with deionized water for 20-30 seconds using the Melnor Rear-Trigger 7-Pattern nozzle set to shower mode described above. Panels were warm air dried using the Hi-Velocity handheld blow-dryer made by Oster® described above on high-setting at a temperature of 50 C-55 C until the panel was dry (1 minute to 5 minutes).
Panel Set 12 was a comparative panel aluminum 6111 zinc phosphate treated panel purchased from ACT Test Panels (Product No. 42606, ACT Zinc Phosphate 6111AA panel) and was heated as described below for colorimeter data.
Panels were analyzed for deposition of cerium, phosphorous, and zinc using X-ray fluorescence (measured using X-Met 7500, Oxford Instruments; operating parameters for cerium 60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.1 μs; operating parameters for phosphorus 60 second timed assay, 25Kv, 20 μA, filter 1, T(p)=1.1 μs; operating parameters for zinc 60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.1 μs). Data are reported in Table 5, with each reported value being the average of two measurements taken at different positions on each panel.
Panels also were measured for yellowness of the panels following conversion composition (measured using an X-rite Ci7800 Colorimeter, 25 mm aperture). Data are reported in Table 6, with each reported value being the average of two measurements taken at the same position on the panel. Data reported are Spectral Component Excluded.
1Yellowness index measurement according to ASTM E313-00
Next, panels were baked in an oven (Despatch Model LFD-1-42) at 177° C. for 25 minutes (panels were not electrocoated). The panels were measured for yellowness of the panels heating of the pretreated panels (measured using an Xrite Ci7800 Colorimeter, 25 mm aperture). Data are reported in Table 6.3, with each reported value being the average of two measurements taken at the same position on the panel. Data reported are Spectral Component Excluded.
The b* value and YI-E313 value of panels pretreated only with the cerium-containing composition had increased b* value compared to zinc phosphate treated panels, indicating that the cerium-treated panel had a more yellow coloration. Notably, the b* value and YI-E313 value were significantly lower in heated panels pretreated with cerium only compared to unheated panels pretreated in the same way, indicating that heating of the panels further reduces the yellow coloration of the panels. Furthermore, the b* and YI-E313 value of panels pretreated with the cerium-containing composition were lower after heating panels compared to untreated and heat panels treated with conventional zinc phosphate.
This application claims priority to U.S. Provisional Application No. 62/374,188, filed on Aug. 12, 2016 and entitled “Sealing Composition” and to U.S. Provisional Application No. 62/374,199, filed Aug. 12, 2016 and entitled “Pretreatment Composition”, both of which are incorporated in their entirety herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/046764 | 8/14/2017 | WO | 00 |
