Patent Application
20190040531
The present invention relates to a surface treatment agent for treating treat the surface of an aluminum material or aluminum alloy material (hereafter simply referred to as “aluminum material or the like”), a method for forming a surface treatment coating using the surface treatment agent, and an aluminum material or the like having the surface treatment coating thereon/over.
Aluminum materials or the like, which have excellent lightness and recyclability, have been used in recent years in various products, including vehicles, two-wheeled vehicles, bicycles, household electrical appliances, drink cans, and aircrafts, in terms of global environmental conservation. Various surface treatments are performed on aluminum materials or the like used in these products for the purpose of providing corrosion resistance to the aluminum material or the like or improving the adhesion to the aluminum material or the like and an upper layer film, such as a coating or laminate film.
Various surface treatment agents that do not contain hexavalent chromium have been developed in recent years as agents used in surface treatments. For example, Patent Literature 1 proposes an aqueous metal surface treatment agent containing one or two or more iron group compounds selected from oxides, hydroxides, or oxyhydroxides of iron, nickel, or cobalt.
An object of the present invention is to provide a non-chromate (“non-chromate” means not containing hexavalent chromium) surface treatment agent that, without using the above iron group compounds, or the like, allows a surface treatment coating having excellent adhesion to an aluminum material or the like and an upper layer film and providing excellent corrosion resistance to the aluminum material or the like to be formed between the aluminum material or the like and the upper layer film, a method for forming a surface treatment coating using the surface treatment agent, and an aluminum material or the like having the surface treatment coating thereon/over.
To solve the above challenge, the present inventors have conducted intensive investigation. As a result, the present inventors have found that a surface treatment agent containing a water-soluble or water-dispersible organic polymer (A) having a carbonyl group and/or hydroxyl group in a unit structure and an organic polymer (B) having a phosphonic group allows a surface treatment coating having excellent adhesion to an aluminum material or the like and an upper layer film and providing excellent corrosion resistance to the aluminum material or the like to be formed between the aluminum material or the like and the upper layer film, and then completed the present invention.
The present invention provides the following and others:
an organic polymer (B) having a phosphonic group; and optionally a metal compound (C), wherein
if the surface treatment agent comprises the metal compound (C), a ratio of the mass of metal (MM) in the metal compound (C) to the mass of phosphorus (MP) in the organic polymer (B), MM/MP, is 0.30 or less, and
the surface treatment agent does not comprise any of iron, nickel, cobalt, hexavalent chromium, compounds including metals thereof, and an amine compound having three or more hydroxyl groups in one molecule.
the surface treatment coating comprises:
if the surface treatment coating comprises the metal compound (C), a ratio of the mass of metal (MM) in the metal compound (C) to the mass of phosphorus (MP) in the organic polymer (B), MM/MP, is 0.30 or less, and
the surface treatment coating does not comprise any of iron, nickel, cobalt, hexavalent chromium, compounds including metals thereof, and an amine compound having three or more hydroxyl groups in one molecule.
According to the present invention, there can be provided a non-chromate surface treatment agent that, without using the above iron group compounds, or the like, allows a surface treatment coating having excellent adhesion to an aluminum material or the like and an upper layer film and providing excellent corrosion resistance to the aluminum material or the like to be formed between the aluminum material or the like and the upper layer film, a method for forming a surface treatment coating using the surface treatment agent, and an aluminum material or the like having the surface treatment coating thereon/over.
Now, an embodiment of the present invention will be described. However, the present invention is not limited to the embodiment below.
A surface treatment agent of the present invention is an agent for treating the surface of an aluminum material or the like. A surface treatment coating is formed by bringing this surface treatment agent into contact with the surface of an aluminum material or the like. The surface treatment agent comprises a water-soluble or water-dispersible organic polymer (A) having a carbonyl group and/or hydroxyl group in a unit structure and an organic polymer (B) having a phosphonic group. If a surface treatment coating is formed between the aluminum material or the like and an upper layer film (e.g., a coating, laminate layer) using this surface treatment agent, the surface treatment coating can exhibit excellent adhesion to the aluminum material or the like and the upper layer film, as well as can provide high corrosion resistance to the aluminum material or the like. The surface treatment coating formed on the aluminum material or the like also has excellent retort resistance. For this reason, an aluminum material or the like having this surface treatment coating thereon/over is useful as packaging containers for foods or the like, food cans, drink cans, lids of these containers or cans, or the like. As used herein, the term “retort resistance” refers to the properties of the surface treatment coating of the aluminum material or the like that suppress discoloration (e.g., whitening), peeling, rupture, or the like of the surface treatment coating when the surface treatment coating comes into contact with the liquid component (e.g., aqueous solution) of sterilized or heated retort food or the like. Examples of the aqueous solution include, but not limited to, pure water, tap water, a saline solution, an aqueous solution of an acid such as citric acid or acetic acid, and an aqueous alkali solution such as an aqueous ammonia solution.
The surface treatment agent of the present invention may comprise only organic substances, for example, only the above organic polymer (A) and organic polymer (B), except for a solvent (to be discussed later). However, it may comprise other components such as a metal compound (C) unless the performance (adhesiveness, corrosion resistance, retort resistance) of the surface treatment coating is impaired. Note that the surface treatment agent of the present invention does not comprise any of iron, nickel, cobalt, hexavalent chromium, compounds including metals thereof, and an amine compound having three or more hydroxyl groups in one molecule.
As used herein, the term “amine compound” refers to a compound in which all or some hydrogen atoms of ammonia are substituted by other functional groups, that is, a nitrogen-containing compound. Accordingly, the term “an amine compound having three or more hydroxyl groups in one molecule” refers to a nitrogen-containing compound having three or more hydroxyl groups in one molecule. While the surface treatment agent of the present invention does not comprise an amine compound having three or more hydroxyl groups in one molecule as described above, it is preferable that it not have any amine compound.
While one characteristic of the surface treatment agent of the present invention is that it does not comprise any of iron, nickel, cobalt, and compounds including metals thereof, inevitable entry of these components is allowed. Note that if these components are comprised in the surface treatment agent, the allowed mass concentration of the components is 5 ppm or less.
The organic polymer (A) is a water-soluble or water-dispersible polymer having a carbonyl group and/or hydroxyl group in a unit structure. Since the organic polymer (A) comprised in the surface treatment agent used to form a surface treatment coating contains a carbonyl group or hydroxyl group, which is a polar part, the surface treatment coating exhibits higher adhesion to an upper layer film and an aluminum material or the like. Preferably, the organic polymer (A) having a carboxyl group or carboxylate ester group in a unit structure.
The organic polymer (A) may have other substituents or functional groups as long as it has a carbonyl group or hydroxyl group in a unit structure. The organic polymer (A) may be an ionic organic polymer or may be a nonionic organic polymer. The ionicity may be ampholytic, anionic, or cationic.
Specific examples of the organic polymer (A) include known ones such as polyester-based copolymers, (meth) acrylic-based polymers or copolymers, and polyvinyl-based polymers or copolymers. These organic polymers may be used alone or in combination.
Examples of polyester-based copolymers include polyester polyols obtained by condensing polyvalent carboxylic acids, such as maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, and naphthalenedicarboxylic acid, and polyols, such as ethylene glycol, diethylene glycol, trimethylolpropane, neopentylglycol, 1,4-cyclohexanedimethanol, and 1,6-hexanediol; and condensation polymers of the above polyvalent carboxylic acids and polyols, such as polymer polyol, polycarbonate diol, polybutadiene polyol, polycaprolactone polyol, neopentylglycol, and methyl penta diol. Other examples include copolymers of the above polyester polyols or condensation polymers and other types of polymers. Examples of other types of polymers include, but not limited to, (meth)acrylic-based polymers and polyvinyl-based polymers. As used herein, the term “polyvalent carboxylic acids” refers to compounds having two or more carboxyl groups. Instead of the above substances, dimer acid or trimer acid of unsaturated fatty acid may be used as a polyvalent carboxylic acid.
Examples of polyester-based copolymers also include a substance obtained by neutralizing, with alkali, an unreacted carboxyl group included in a copolymer of monomers having three or more carboxyl groups in trimellitic acid, pyromellitic acid, or the like, or a substance obtained by sulfonating the above copolymer with sulfophthalic acid or the like. Use of such an alkali-neutralized substance or sulfonated substance facilitates dissolution or dispersion in water.
Examples of (meth)acrylic-based polymers or copolymers include polymers or copolymers of (meth)acrylic monomers and copolymers of polymers or copolymers of (meth)acrylic monomers and sequentially polymerizable monomers that are polymerizable therewith. (Meth) acrylic-based polymers or copolymers maybe in any polymerization form as long as they are water-soluble or water-dispersible. Examples of the polymerization form of (meth)acrylic-based copolymers include block copolymer, graft copolymer, random copolymer, and alternating copolymer. Examples of sequentially polymerizable monomers include monomers used to prepare polyester-based copolymers.
Examples of (meth)acrylic monomers include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-acrylamide-2-methylpropanecarboxylic acid, muconic acid, citraconic acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-acrylamide ethylsulfonic acid, vinyl sulfonic acid, sulfoethyl acrylate, sulfoethyl methacrylate, styrenesulfonic acid, (meth)acryl sulfonic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-methoxyethyl acrylate, allyl (meth)acrylate, N-allyl (meth) acrylamide, N,N-diaryl(meth)acrylamide, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, tripropylene glycol mono(meth)acrylate, tetrapropylene glycol mono(meth)acrylate, polytrimethylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, and polyethylene glycol mono(meth)acrylate.
(Meth)acrylic monomers can be polymerized appropriately using a known method. One specific example of the polymerization method is to polymerize any type of (meth) acrylic monomers in the presence of any known radical polymerization initiator and optionally a chain transfer agent in a solvent or inert gas. The polymerization reaction temperature and time may be any temperature or time. The reaction temperature is, for example, 20° C. or more and 140° C. or less, and the reaction time is, for example, 1 h or more and 24 h or less.
Examples of a radial polymerization initiator that can be used to polymerize (meth)acrylic monomers include organic peroxides such as benzoyl peroxide, dicumyl peroxide, and lauryl peroxide; inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate; and azo-based compounds such as 2,2′-Azobis(isobutyronitrile) and dimethyl-2,2′-azobisisobutyrate. These substances may be used alone or in combination. Examples of a chain transfer agent that can be used to polymerize (meth)acrylic monomers include ethyl alcohol, methyl alcohol, and isopropyl alcohol.
Examples of (meth)acrylic-based copolymers include a copolymer of acrylic acid and maleic acid; a copolymer of a copolymer of maleic acid and trimethylolpropane, and methacrylic acid; and a copolymer of polyvinyl acetate and fumaric acid.
Examples of polyvinyl-based polymers include polyvinyl alcohol.
Examples of polyvinyl alcohol include partially and completely saponified products of polyvinyl acetate and partially and completely saponified products of a copolymer of vinyl acetate and another monomer. The degree of saponification of a partially saponified product of polyvinyl acetate or a copolymer of vinyl acetate and another monomer has no upper limit and is preferably 60% or more. Examples of a monomer that forms a copolymer with vinyl acetate include the above (meth)acrylic monomers.
Examples of polyvinyl-based copolymers include a copolymer of an acrylic acid polymer and vinyl acetate; and a copolymer of a copolymer of glutaric acid and ethylene glycol, and vinyl acetate.
The weight average molecular weight of the organic polymer (A) is preferably 2,000 or more and 1,000,000 or less, more preferably 4,000 or more and 800,000 or less. As used herein, the term “weight average molecular weight” refers to a polystyrene-converted value of a weight average molecular weight measured by gel permeation chromatography (GPC).
The organic polymer (B) may be any type of organic polymer as long as it has a phosphonic group (—PO3H2).
Examples of the organic polymer (B) include aminotrimethylene phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonate, 2-phosphobutanone-1,2,4-tricarboxylic acid, cytidine triphosphate, cytidine diphosphate, cytidylic acid, uridine diphosphate, cytidine-5′-phosphate, adenosine-3′-phosphate, phosphoserine, ethylene diamine tetra (methylene phosphonic acid), N-phosphonomethyl iminodiacetic acid, ethylenediamine-N,N′-di(methylene phosphonic acid), ethylene diamine-N,N,N′,N′-tetra(methylene phosphonic acid), cyclohexane-1,2-diamine-N,N,N′,N′-tetra(methylene phosphonic acid), N,N′-bis(2-hydroxybenzyl)ethylene diamine-N,N′-bis(methylene phosphonic acid), [hexamethylene bis(nitrilo)tetrakis(methylene)]tetrakis phosphonic acid, inositol hexaphosphate, inositol pentaphosphate, inositol tetraphosphate, inositol trisphosphate, inositol bisphosphate, inositol monophosphate, dibenzyl phosphate, phosphoric acid 1-benzyl-3-methyl imidazolium, phosphoric acid 1-butyl-3-methyl imidazolium, erythrose-6-phosphate, erythrose-4-phosphate, phosphoenolpyruvic acid, fructose 6-phosphate, fructose-2,6-bisphosphate, fructose-1,6-bisphosphate, glucose-6-phosphate, glucose-4-phosphate, glucose-3-phosphate, glucose-2-phosphate, and glucose-1-phosphate. These organic compounds may be used alone or in combination.
The organic polymer (B) is preferably a phosphonic group-containing compound having three or more carbon atoms and two or more phosphonic groups in one molecule. The number of phosphonic groups has no upper limit and is preferably three or more. The carbon number is preferably 30 or less, more preferably 10 or less. Use of a surface treatment agent comprising a phosphonic group-containing compound having two or more phosphonic groups in one molecule allows for formation of a surface treatment coating having more excellent adhesion to an upper layer film.
Preferable combinations of the organic polymer (A) and the organic polymer (B) include a combination of a polyester-based copolymer serving as the organic polymer (A) and the organic polymer (B); and a combination of a (meth)acrylic-based polymer or copolymer serving as the organic polymer (A) and the organic polymer (B). Use of a surface treatment agent containing the organic polymer (A) and organic polymer (B) combined described above allows for formation of a surface treatment coating that also has excellent acid and alkali resistance.
Examples of a combination of a polyester-based copolymer serving as the organic polymer (A) and the organic polymer (B) include a combination of a copolymer of maleic acid and polyol, and 1-hydroxyethylidene-1,1-diphosphonate, [hexamethylenebis (nitrilo) tetrakis (methylene)]tetrakis phosphonic acid, 2-phosphobutanone-1,2,4-tricarboxylic acid, or ethylenediamine-N,N′-di(methylene phosphonic acid); a combination of a copolymer of fumaric acid and polyol, and ethylenediamine-N,N,N′,N′-tetra (methylenephosphonic acid) or cyclohexane-1,2-diamine-N,N,N′, N′-tetra (methylenephosphonic acid); a combination of a copolymer of itaconic acid and polyol, and N,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-bis(methylenephosphonic acid); a combination of a copolymer of isophthalic acid and polyol, and inositol hexaphosphate; and a combination of a copolymer of terephthalic acid and polyol, and inositolpentaphosphate.
Examples of a combination of a (meth)acrylic-based polymer or copolymer serving as the organic polymer (A) and the organic polymer (B) include a combination of a polymer or copolymer of acrylic acid, and 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediamine-N,N′-di(methylenephosphonic acid), ethylenediamine-N,N,N′,N′-tetra(methylenephosphonic acid), cyclohexane-1,2-diamine-N,N,N′,N′-tetra(methylenephosphonic acid), inositol hexaphosphate, inositol pentaphosphate, inositol tetraphosphate, inositol trisphosphate, or inositol bisphosphate; a combination of a polymer or copolymer of methacrylic acid, and ethylenediamine-N,N′-di(methylenephosphonic acid), ethylenediamine-N,N,N′,N′-tetra(methylenephosphonic acid), cyclohexane-1,2-diamine-N,N,N′,N′-tetra(methylenephosphonic acid), inositol pentaphosphate, inositol tetraphosphate, inositol trisphosphate, or inositol bisphosphate; a combination of a polymer or copolymer of maleic acid, and ethylenediamine-N,N′-di(methylenephosphonic acid), ethylenediamine-N,N,N′,N′-tetra(methylenephosphonic acid), cyclohexane-1,2-diamine-N,N,N′,N′-tetra(methylenephosphonic acid), inositol tetraphosphate, inositol trisphosphate, or inositol bisphosphate; a combination of a polymer or copolymer of fumaric acid, and ethylenediamine-N,N′-di(methylenephosphonic acid), ethylenediamine-N,N,N′,N′-tetra(methylenephosphonic acid), cyclohexane-1,2-diamine-N,N,N′,N′-tetra(methylenephosphonic acid), inositol trisphosphate, or inositol bisphosphate; a combination of a polymer or copolymer of diethylene glycol mono(meth)acrylate, and ethylenediamine-N,N′-di(methylenephosphonic acid), ethylenediamine-N,N,N′, N′-tetra(methylenephosphonic acid), fructose-6-phosphate, fructose-2,6-bisphosphate, or fructose-1,6-bisphosphate; and a combination of a polymer or copolymer of triethylene glycol mono (meth) acrylate, and fructose-2,6-bisphosphate.
The mixture mass ratio of phosphorus (P) in the organic polymer (B) to the organic polymer (A), MP/MA, is preferably 0.001 or more and 0.70 or less, more preferably 0.001 or more and 0.60 or less. Use of a surface treatment agent whose mass ratio MP/MA is within this range allows for formation of a surface treatment coating having higher adhesion to an aluminum material or the like and an upper layer film.
The surface treatment agent of the present invention may optionally contain the metal compound (C). Examples of the metal compound (C) include metal compounds having one or more transition metals except for compounds containing a metal such as iron, nickel, cobalt, or hexavalent chromium and preferably also compounds having a metal such as vanadium or trivalent chromium. More preferably, the surface treatment agent of the present invention does not contain not only these compounds, but also a metal such as iron, nickel, cobalt, hexavalent chromium, vanadium, or trivalent chromium. The surface treatment agent of the present invention particularly preferably contains a metal compound containing one or more transition metals selected from Ti, W, Mn, Zr, Ce, and the like (except for compounds containing a transition metal other than these five metals). Note that inevitable entry of a metal such as iron, nickel, or cobalt, or a compound containing such a metal into the surface treatment agent is allowed. The allowed mass concentration of these components is 5 ppm or less.
Examples of the metal compound (C) include oxides, hydroxides, complex compounds, inorganic acids, and organic acids of the above transition metals. More specific examples thereof include titanyl sulfate, titanium lactate, titanium fluoride, titanium ammonium fluoride, titanium hydrofluoric acid, ammonium metatungstate, ammonium tungstate, paratungstic acid, ammonium paratungstate, permanganic acid, manganese dihydrogenphosphate, manganese nitrate, manganese sulfate, manganese acetate, zirconium acetate, zirconium fluoride, zircon hydrofluoric acid, zircon ammonium fluoride, zirconium sulphate, fluorozirconic acid, zirconium oxonitrate, ammonium zirconium carbonate, cerium acetate, cerium nitrate, cerous fluoride, and cerium (TV) nitrate ammonium. The metal compound (C) is coordinately bonded with the organic polymer (B) and organic polymer (A), allowing for formation of a surface treatment coating having higher corrosion resistance.
If the surface treatment agent of the present invention contains the metal compound (C), the ratio of the mass of metal (MM) in the metal compound (C) to the mass of phosphate (MP) in the organic polymer (B), (MM/Mp), is 0.30 or less.
The surface treatment agent of the present invention may or may not contain a compound having a benzenetriol structure, as a component other than the metal compound (C).
The surface treatment agent of the present invention may optionally contain a solvent in terms of contactability with an aluminum material or the like. Examples of a solvent include water; alkane-based solvents such as hexane and pentane; aromatic-based solvents such as benzene and toluene; alcohol-based solvents such as ethanol, 1-butanol, and ethylcellosolve; ether-based solvents such as tetrahydrofuran and dioxane; ester-based solvents such as ethyl acetate and butoxyethyl acetate; amide-based solvents such as dimethylformamide and N-methylpyrrolidone; sulfone-based solvents such as dimethyl sulfoxide; and phosphoric amide-based solvents such as hexamethylphosphoric triamide. These solvents may be used alone or in combination. Preferably, water is used as a solvent in environmental and economic terms.
A surface treatment agent maybe prepared using any method. For example, a surface treatment agent can be prepared by sufficiently mixing the organic polymer (A), the organic polymer (B), and a solvent and optionally further mixing the metal compound (C) and other components. The pH of the surface treatment agent is preferably 1.5 or more and 6.5 or less. The pH can be adjusted using a pH adjustor, such as any acid or an alkaline agent such as ammonia.
A surface treatment coating of the present invention can be formed by bringing the above surface treatment agent into contact with an aluminum material or the like. More specifically, a method for forming a surface treatment coating includes a contact step of bringing the surface treatment agent into contact with the surface of an aluminum material or the like and a drying step of drying the surface treatment agent in contact with the surface of the aluminum material or the like after the contact step. Note that in the surface treatment coating formation method, a degreasing step, a pickling step, a chemical conversion step, and/or other steps may be performed on the surface of the aluminum material or the like before the contact step. Also, a water-rinsing step of water-rinsing the surface of the aluminum material or the like having the surface treatment coating in contact therewith may or may not be performed between the contact step and drying step.
An aluminum material or the like that the surface treatment agent is to be brought into contact with is an aluminum-containing metal material, such as an aluminum material or aluminum alloy material. Examples of an aluminum material include a 1000-family pure aluminum material defined in JIS 2014 H4000. As used herein, the term “aluminum alloy material” refers to a metal material containing aluminum as a main component and, specifically, refers to a metal material that consists of aluminum and another metal component and contains 50% by weight or more of aluminum, or a metal material that consists of aluminum and other two or more metal materials and contains aluminum as the largest component. More specific examples include, but not limited to, 3000-familiy and 5000-familiy aluminum alloy materials defined in JIS 2014 H4000.
The contact step can be performed using known contact methods including, but not limited to, spraying, dipping, roll coating, bar coating, curtain coating, spin coating, and combinations thereof.
In the contact step, the surface treatment agent may be used under any conditions. For example, when bringing the surface treatment agent into contact with the aluminum material or the like, the temperature of the surface treatment agent or aluminum material or the like is preferably 10° C. or more and 70° C. or less, more preferably 20° C. or more and 60° C. or less. The contact time is preferably 1 s or more and 300 s or less.
The drying step is preferably performed under temperature conditions such that the peak metal temperature (PMT) of the aluminum material or the like is 20° C. or more and 300° C. or less. The drying time is preferably 2 s or more and 150 s or less. Any drying method may be used, and known drying apparatuses, including a batch drying oven, a continuous hot air circulation drying oven, a conveyor hot air drying oven, and an electromagnetic induction heating oven using an IH heater, maybe used. If these ovens are used, the air rate or air speed is set appropriately.
The degreasing step is a step of removing oils and fats or dirt adhering to the surface of the aluminum material or the like. The degreasing step may be performed using any method as long as cissing (a phenomenon in which when bringing the surface treatment agent into contact with the surface of the aluminum material or the like, the agent is rejected and a hole or recess is formed) can be prevented and oils and fats or dirt can be removed to the extent that the subsequent surface treatment or chemical conversion is not affected. For example, a known degreasing method using an alkaline or acidic degreasing agent or the like may be used.
The pickling step is a step of cleaning the surface of the aluminum material or the like using an acidic aqueous solution. Examples of an acidic aqueous solution include, but not limited to, an aqueous solution of nitric acid and an aqueous solution of sulfuric acid. The pickling temperature and time are set appropriately.
The chemical conversion step is a step of bringing a chemical conversion agent into contact with the surface of the aluminum material or the like to form a chemical conversion coating. The corrosion resistance of the aluminum material or the like can be increased by the chemical conversion step. As seen above, by performing the chemical conversion step and then the contact step on the surface of the aluminum material or the like, a multilayer film including the chemical conversion coating and the surface treatment coating can be formed on the surface of the aluminum material or the like.
Examples of a chemical conversion agent include, but not limited to, a zirconium chemical conversion agent, a phosphate chemical conversion agent, a titanium chemical conversion agent, and a chromate chemical conversion agent. A chemical conversion agent that does not contain chromate (including trivalent chromium) is preferred. Examples of a chemical conversion agent contact method include known ones, including, but not limited to, spraying, dipping, roll coating, bar coating, curtain coating, spin coating, and combinations thereof. When performing the chemical conversion step, the temperature of the chemical conversion agent or aluminum material or the like is preferably 5° C. or more and 70° C. or less. The chemical conversion time is preferably 1 s or more and 300 s or less.
After the chemical conversion step and before the surface treatment agent contact step, it is preferred to perform a water-cleaning step of water-cleaning the surface of the aluminum material or the like, that is, the surface of the chemical conversion coating. After the water-rinsing step and before the surface treatment agent contact step, a drying step of drying the surface of the aluminum material or the like having the chemical conversion coating thereon/over may or may not be performed. The drying temperature in the drying step is preferably 20° C. or more and 300° C. or less, more preferably 80° C. or more and 180° C. or less. The drying time is preferably 2 s or more and 300 s or less, 30 s or more and 150 s or less.
A surface treatment coating can be formed using the above formation method. The mass of the surface treatment coating after the drying step (the mass of the dried coating) is preferably 1 mg/m2 or more and 5,000 mg/m2 or less, more preferably 3 mg/m2 or more and 2,000 mg/m2 or less. As used herein, the term “the mass of the dried coating” refers to a value calculated, using the calibration curve method, from the carbon content of the surface treatment coating measured using a total organic carbon (TOC) analyzer. If the surface treatment coating contains the metal compound (C), the “the mass of the dried coating” refers to a value calculated, using the calibration curve method, from the metal compound (C) in the surface treatment coating measured using fluorescent X-rays.
An aluminum material or the like having the surface treatment coating thereon/over according to the present invention may be in any form as long as the aluminum material or the like has the surface treatment coating on the surface thereof. For example, it may further have an upper layer film on the surface treatment coating.
An upper layer film is a film formed on the surface treatment coating. Examples of an upper layer film include a coating and a laminate layer. A coating consists of a layer containing an organic resin. A laminate layer is a layer in which two or more layers containing organic resins are laminated. The organic resins contained in the layers of the laminate layer may be the same or different.
For example, a coating can be formed by bringing a coating solution containing an organic resin into contact with the surface treatment coating and then drying it. Examples of a contact method include, but not limited to, spraying, dipping, roll coating, bar coating, curtain coating, spin coating, electrodeposition coating, powder coating, electrostatic coating, and combinations thereof. Examples of a drying method include, but not limited to, use of known drying apparatuses, including a batch drying oven, a continuous hot air circulation drying oven, a conveyor hot air drying oven, and an electromagnetic induction heating oven using an IH heater. The coating is preferably dried under temperature conditions such that the peak metal temperature (PMT) of the aluminum material or the like is 20° C. or more and 300° C. or less. The drying time is preferably 2 s or more and 150 s or less.
Examples of a laminate layer formation method include, but not limited to, dry lamination, extrusion lamination, and a combination thereof. More specifically, the aluminum material or the like having a laminate film thereon/over can be formed by stacking laminate films (may include an adhesive layer) on the surface treatment coating formed on the surface of the aluminum material or the like and thermally compressing them.
Examples of an organic resin(s) contained in a coating or the layers of a laminate layer include, but not limited to, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), polycarbonate (PC), polyphenylene sulfide (PPS), triacetylcellulose (TAC), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyester, polyolefin, polyurethane, nylon, acrylic, an epoxy resin paint, and a vinyl organosol-based resin.
The present invention will be described in more detail using Examples and Comparative Examples. However, the present invention is not limited to Examples below.
Table 1 shows the compositions of surface treatment agents of Examples 1 to 35 and surface treatment agents of Comparative Examples 1 and 2. Signs shown in the “type” fields of organic polymers, organic compounds, and metal compounds in Table 1 represent substances shown in Tables 2 to 4. Values in the “mass o” fields of the components of each surface treatment agent in Table 1 represent the percentages (%) of the masses of the components with respect to the total mass of the solid components of the surface treatment agent. The surface treatment agents were prepared by mixing the components using water as a solvent.
Aluminum alloy plates (JIS 2014 H4000 A5182 material) were degreased by spraying a degreasing agent (FINECLEANER 4477 available from Nihon Parkerizing Co., Ltd.; agent concentration 2%) on the plates at 60° C. for 5 s and then rinsedwith water. Then, the aluminum alloy plates were pickled by spraying 2% of sulfuric acid at 50° C. on the plates for 3 s and then the surfaces thereof were rinsed with water. Then, surface treatments were performed. Specifically, surface treatment coatings were formed on the degreased and pickled surfaces of the aluminum alloy plates by spraying the surface treatment agents (the surface treatment agents of Examples 1 to 29 and Comparative Examples 1 and 2) on the surfaces for 2 s and then drying the surfaces in a hot air circulation drying oven at 100° C. for 7 s.
As for Examples 30 to 35, chemical conversion was performed. Specifically, a chemical conversion coating was formed on the degreased and pickled surfaces of the aluminum alloy plates by spraying a zirconium phosphate chemical conversion agent (ALODINE N405, available from Nihon Parkerizing Co., Ltd.) on the surfaces at 55° C. for 4 s, then cleaning them with water, and drying them in a hot air circulation drying oven at 70° C. for 10 s. Then, surface treatments were performed. Specifically, surface treatment coatings were formed on the surfaces of the aluminum alloy plates by spraying the surface treatment agents of Examples 30 to 35 on the chemical conversion coatings for 2 s and then drying them in a hot air circulation oven at 100° C. for 10 s.
An epoxy-based solvent paint was applied to the aluminum alloy plates having the surface treatment coatings thereon/over using a bar coater #26 such that the dried coating thickness becomes 10 μm. Then, the aluminum alloy plates were dried in a hot air circulation drying oven at 300° C. for 15 s to produce Samples Nos. 1 to 37 having coatings on the surface treatment coatings. As a comparison target, Sample No. 38 was produced by forming a chemical conversion coating on the degreased and pickled surface of an aluminum alloy plate as described above and then forming a coating on the chemical conversion coating as described above. Note that the concentrations of the solid components of the surface treatment agents were adjusted appropriately so that the amounts of the surface treatment coatings (the amounts of coatings) of Samples become values shown in Tables 6 and 7.
The corrosion resistance, adhesion, and retort resistance of Samples Nos . 1 to 38 were evaluated using a method and evaluation criteria below. Note that evaluation results c (unfavorable) and d (unsatisfactory) indicate that the Sample is impractical.
Each Sample was crosscut and immersed in an aqueous solution of 1% of citric acid and 0.5% of sodium chloride at 70° C. for 72 h. Then, the maximum expansion width of one side of the crosscut portion and the maximum expansion width of the normal portion (the portion that was not crosscut) were measured, and both portions were evaluated for corrosion resistance in accordance with evaluation criteria below. The results are shown in Tables 6 and 7.
The surface opposite to the coating-formed surface of each Sample was deformed with DuPont method weight-drop impact processing (½ inch, weight 1000 g, height 100 mm) and immersed in an aqueous solution of 1% of citric acid and 0.5% of sodium chloride at 70° C. for 72 h. Then, the rust area of the processed portion was measured, and the processed portion was evaluated for corrosion resistance in accordance with evaluation criteria below. The results are shown in Tables 6 and 7.
A grid tape peeling test according to JIS K 5400 was conducted. The coating-formed surface of each Sample was crosscut in a grid using a cutter (available from NT Incorporated), and a cellophane tape was affixed to the crosscut portion and then peeled. At this time, the coating-formed surface was crosscut in a grid such that 1 mm-spaced 11 horizontal parallel lines and 1 mm-spaced 11 vertical parallel lines cross each other at right angles to form 100 cells. Then, the remaining cells were measured, and each Sample was evaluated for film adhesion in accordance with evaluation criteria below. The results are shown in Tables 6 and 7.
The entire Samples were immersed in test solutions 1 to 4 shown in Table 5, then pressed at 15 MPaG, and heat-treated at 125° C. for 30 min. Then, Samples were evaluated for various types of retort resistance (whitening resistance, adhesion (1), adhesion after processing, adhesion (2), or the like), as will be discussed later. As for adhesion after processing, the surface opposite to the coating-formed surface of each Sample was deformed with DuPont method weight-drop impact processing (½ inch, weight 1000 g, height 100 mm), and the entire Sample was immersed in the test solutions and heat-treated, and then evaluated for adhesion after processing. As for adhesion (2), a triangular notch having a vertex of 30° was formed in the surface opposite to the coating-formed surface of each Sample, and the Sample was partially immersed in the test solutions such that at least the notch was not immersed in the test solutions and heat-treated, and then evaluated for adhesion (2).
The appearance of each Sample was observed, and the Sample was evaluated for whitening resistance in accordance with evaluation criteria below. The results are shown in Tables 6 and 7.
After the heat treatment, a grid tape peeling test according to JIS K 5400 was conducted, and each Sample was evaluated for adhesion (1) in accordance with evaluation criteria below. The results are shown in Tables 6 and 7.
After the heat treatment, a cellophane tape was affixed to the deformed portion (recess) with DuPont weight-drop and impact processing and then peeled. The area of the peeled coating was measured, and each Sample was evaluated for adhesion after processing in accordance with evaluation criteria below. The results are shown in Tables 6 and 7.
After the heat treatment, the notch of each Sample was pulled up at 200 mm/min using a tensile tester so the notch was ruptured from the Sample. The width of the coating remaining on the ruptured end surface was measured, and each Sample was evaluated for adhesion (2) in accordance with evaluation criteria below. The results are shown in Tables 6 and 7.
As shown in Tables 6 and 7, Samples Nos. 1 to 35 having thereon/over the surface treatment coating formed using the surface treatment agents of Examples 1 to 35 exhibited excellent corrosion resistance and adhesion, as well as excellent retort resistance. Also, as shown in Tables 6 and 7, Samples Nos. 30 to 35, subjected to the chemical conversion and surface treatment, exhibited particularly excellent corrosion resistance.
On the other hand, Samples Nos. 36 and 37 having the surface treatment coatings formed using the surface treatment agents (Comparative Examples 1 and 2) containing only one of the organic polymer (A) and organic polymer (B) did not exhibit a practical level of retort resistance or corrosion resistance.
Samples Nos. 4 to 6, 22 to 29, and 33 to 35 having the surface treatment coatings formed using the surface treatment agents containing the metal compound (C) so that MM/MP becomes 0.30 or less exhibited high corrosion resistance.
The surface treatment agent of the present invention is useful to form a coating having excellent retort resistance, adhesion, and corrosion resistance, as well as to produce an aluminum material or the like having such a coating. An aluminum material or the like having such a coating thereon/over is useful as packaging containers for foods or the like, food cans, drink cans, caps for such containers or cans, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-022347 | Feb 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/004118 | 2/3/2017 | WO | 00 |
