Patent Application
20090023850
The present invention generally relates to multi-component paint systems. More particularly, the present invention concerns a multi-component paint system comprising a foundation component and top coat component, which hide colors and provide adhesion on various substrates.
Organic color pigments provide brilliant, i.e., bright and clean, chroma for yellow, red, orange and green that inorganic color pigments do not provide. In color science, three parameters, brightness (L*), chroma (C*) and hue (H*), are used to represent the qualities of a given color. The C*, which is a measurable parameter, is expressed as the distance of a color in the color space to the central point. The further away a color is from the central point, the larger the C* is and the cleaner or clearer the color is. In a deep base or clear base with little or no inorganic color pigments, organic pigments are the primary choices for achieving bright, clear and highly saturated colors. Blending inorganic white or other color pigments with an organic pigment results in a loss of the brilliant chroma of the organic pigment.
In conventional tint-based paint systems, a single paint product that has been tinted to the desired color is applied to a substrate, e.g., a wall. The paint product having the desired color is obtained by adding from about 1 to about 15% by volume of color concentrates made with primary color pigments to a tint base. The color concentrates made from organic color pigments typically contain organic color pigment from about 1 to about 30% by volume. Therefore, a clear base paint with maximum loading of organic pigment load at about 15% will contain organic pigment no more than about 5% by volume. At these pigment concentrations, however, paint products containing organic yellow, orange, red and green colors lack the opacity necessary to produce the desired color on the substrate and to provide the desired level of hiding of existing substrate colors, markings or patterns. In order to overcome these limitations and to achieve the desired colors and necessary hiding qualities, these paint products are conventionally applied in multiple overlapping coats, for example from at least three to eight or more coats of paint. For example, four to eight coats are required for colors such as yellow, light green, organic red or orange to achieve the desired level of hiding when applied on a white wall containing dark stripes.
Alternate attempts at achieving improved hiding characteristics use a mixture of inorganic pigments and organic pigments in the paint. Although mixtures of organic and inorganic pigment provide the desired color (hue), the brilliant chroma (L* and C*) associated with the organic pigment is decreased. In addition, existing paint systems utilize separate primer coats, e.g., a white primer, to achieve additional hiding of existing substrate colors and pattern, in particular when using the paints that contain poor hiding color pigments. White primer coat paint systems, however, typically require the application of at least one and possibly more primer coats in addition to two or more coats of the tinted paint on top of the white primer to overcome or to hide the white color of the primer coat. In an attempt to improve the hiding capabilities of paint systems that utilize a primer coat in combination with the tinted paint, a small amount of non-white color pigment has been added to the relatively large amount of white pigment in the primer. Although the use of tintable primers results in some improved hiding, the number of coats of the tinted paint that are required to be added over the primer coat is still at least two, and the total number of applied coats is still at least three. Therefore, known methods for utilizing organic pigment colors including yellow, orange and red use (1) three or more tinted coats, or (2) one or multiple coats of white primer or tintable primer in combination with one (if multiple primer coats are used) or multiple coats of tinted top coats. All of these known methods require at least three and possibly more coats to provide a sufficient amount of hiding and to achieve the desired color in the finished painted surface.
Two coat paint systems are found in metal coating or automobile painting applications. Examples of these systems are described in, for example, U.S. Pat. Nos. 5,871,827, 5,025,041 and 5,830,567. These systems, however, utilize a heavily tinted base in combination with a clear top coat that is transparent or substantially transparent. The clear top coat is applied for purposes of protecting the base coat and imparting a glossy finish. In addition, the clear top coat may include additives such as metallic flakes or minute amounts of pigment that are added to provide the desired effects to the basecoat, for example a pearlescent appearance. The additives do not significantly diminish the transparency of the clear coat, and the clear coat does not contribute to the hiding properties of the base coat.
In addition to hiding properties, it is also important for paint systems to exhibit good adhesion properties, particularly to chalky substrates. One conventional method for improving the chalk adhesion properties of a coating composition is to add an alkyd resin to the conventional coating composition.
Another method for improving the chalk adhesion properties is to synthesize a polymer blend in a sequential polymerization. Examples of acrylic-based polymer blends made by sequential polymerization processes can be found in U.S. Pat. Nos. 5,990,228 and 6,710,112 B1. Other publications disclose other alternatives to alkyd resin modification in coating compositions. For example, U.S. Patent Application Publication No. 2004/0161542 A1 and U.S. Pat. No. 6,630,533 both disclose compositions containing at least one fatty acid ester.
Commonly-owned, co-pending U.S. patent application Ser. Nos. 11/384,183, filed on Mar. 17, 2006, and 12/052,808, filed on Mar. 21, 2008, disclose latex emulsions containing polymer blends, which provide increased chalky substrate adhesion. More particularly, the inventions relates to a coating composition containing a polymer blend dispersion including a first polymer having a relatively low molecular weight and a relatively low glass transition temperature, and a second polymer having a relatively high molecular weight and a relatively high glass transition temperature. The disclosures of the '183 and '808 applications are incorporated herein by reference in their entirety.
However, there still remains a need for a paint product or paint system that provides both sufficient hiding of a substrate with only two layers or coats, and improved adhesion to various substrates including chalky substrates without comprising mechanical strength and weatherability.
Exemplary inventive embodiments of paint systems and methods for using these paint systems to cover a substrate utilize just two coats or layers, i.e., a foundation base and a top coat to provide the desired amount of hiding of existing walls colors, i.e., opacity, in combination with the desired brightness and chroma (as measured by L* and C*) of organic color pigments for any colors, using any types of color pigments, and on any type of substrate. Paint systems in accordance with the present invention utilize a tintable foundation base component in combination with a top tint-base or top coat component to obtain brilliant colors of any shade of yellow, green, orange and red and to achieve the full opacity of coatings. Minimizing the number of coats to cover a substrate, regardless of the pre-existing color or patterns can result in significant cost savings to the consumers, since a large portion of the costs of painting is associated with labor.
The tintable foundation base component can be either a tintable translucent or white (no organic color pigment) base tinted with color concentrates, or a tintable color base with organic pigments grinded in, for example a red foundation base or a yellow foundation base. The foundation base uses an unconventionally large amount of organic color pigments, for example at least about 8% by volume of organic color pigments when dried, preferably at least about 15% and more preferably at least about 20%, depending on the colors. With a relatively large amount of organic color pigments, the foundation base component can be shaded to obtain any color (hue) that matches or is close to the color of the top coat. In addition, the amount of organic color pigments in the foundation base component is at least about twice, preferably at least about 2.5 times, and more preferably at least about 3 times, as much as the amount of organic color pigments in the top coat component.
Inorganic color pigments may also be included in the foundation base component to enhance the masking or hiding properties of the foundation base component and the final paint system. The volume ratio of organic color pigment to inorganic color pigment in the foundation base component is selected to be at least about 0.5, preferably at least about 1.0 and more preferably at least about 2.0. This ratio can be as high as desired, since the inclusion of inorganic color pigment is optional. Since using a mixture of organic and inorganic pigments will improve the hiding at the cost of losing the chroma of organic pigment components, no inorganic color pigment is used in some embodiments. In one embodiment, the foundation base component includes color concentrates to obtain color matching to the top coat.
The top coat component also contains primarily organic color pigments. In one embodiment, at least about 80% by volume, preferably at least about 85%, more preferably at least about 90% of all color pigments in the top coat component are organic color pigments, therefore retaining the characteristics of brightness and chroma of organic pigments. While the foundation base component is formulated to provide the desired opacity and hue in the final product, the top coat is formulated to enhance the brightness and cleanness of the coatings. The combination of the two coats is sufficient to offer the brightness, cleanness and full opacity for any shade of color including orange, yellow, reds and green on any type of substrate. Paint systems formulated in accordance with the present invention require only two coats to obtain the desired hiding for any shades of yellow, red, orange, and green without sacrificing brightness and cleanness.
In another embodiment, the foundation base component comprises at least one low molecular weight polymer that undergoes self-crosslinking at ambient conditions during and after paint drying. The low molecular weight polymer can have a number average molecular weight less than about 40,000 Daltons, a polydispersity index of less than about 4.5, and a glass transition temperature from about −20° C. to about 60° C. The low molecular weight polymer penetrates various substrates, including chalky surfaces, to provide improved adhesion. Moreover, because the low molecular weight polymer is self-crosslinking at ambient conditions, the polymer enhances the performance of dried paints, including improving mechanical strength, weatherability, and tannin block properties.
In the accompanying drawings, which form part of the specification and are to be read in conjunction therewith:
Paint systems in accordance with exemplary embodiments of the present invention include a foundation base component and a top coat component. The foundation base component is a tintable color base or a clear base that is shaded or colored with color concentrates to match or substantially match the color of the top coat component. The foundation base component is preferably not a white foundation base or white primer that can affect or change the color of the top coat unless the color of the top coat is white. Instead, the foundation base component is tinted to match the top coat component to provide both the desired amount of hiding of colors or markings on the substrate to which the paint system is applied, and to enhance the brightness and hue of the color of the paint system.
The foundation base and the top coat are paints that are capable of forming films and generally contain a binder, a diluent, one or more color pigments and other additives including fillers. The binder eventually solidifies to form the dried paint. Depending on the type of binder, this solidification or hardening may be a result of a chemical reaction or curing (polymerization), evaporation, i.e., drying, or even cooling. In one embodiment, the binder dries to form a solid film when the diluent or solvent evaporates. In another embodiment, the binder is a polymer binder that solidifies during curing or polymerization. Typical binders include synthetic or natural resins such as acrylics, polyurethanes, polyesters, melamines, oils, or latex. Examples of suitable polymers include, but are not limited to, high molecular weight organic materials including polyacrylics, polymethacrylics, polyesters, polyurethanes and copolymers thereof. Alternatively, cured binder films are formed from crosslinkers, such as polyurethane or melamine resins, reacted with acrylic polyester or polyurethane resins, often in the presence of a catalyst which serves to make the curing reaction proceed more quickly or under milder conditions. These cured-film paints can be either solvent-borne or waterborne. Preferably, the binder used in the foundation base component is a polymeric binder.
In addition, other suitable waterborne paints are emulsions of solid binders in water. Upon evaporation of the diluent, the molecules of the binder coalesce to form a solid film. Such emulsion paints are also known as latex paints because the polymer is formed through an emulsion polymerization through which the monomers are emulsified in a water-continuous phase. Since the polymer is not soluble in water, the dried paint is water resistant. Other types of binders form films as a result of cooling. For example, encaustic or wax paints are liquid when warm, and harden upon cooling.
Suitable diluents are known and available in the art and are selected based upon the type of binder that is being used. Examples of diluents include, but are not limited to, organic solvents such as alcohols, ketones, esters, glycol ethers and combinations thereof. Other diluents include water and volatile low-molecular weight synthetic resins.
Other additives can be included in the foundation base component depending upon the application to which the paint is used or based upon desired qualities in the paint systems. These additives include, but are not limited to, catalysts, thickeners, stabilizers, emulsifiers, texturisers, adhesion promoters, flatteners (de-glossing agents), UV absorbers and hindered amine light stabilizers, dispersants, wetting agents, anti-settling agents and combinations thereof. The additives also include one or more fillers. In general, fillers serve to thicken the film, support its structure and simply increase the volume of the paint. Common fillers are inexpensive and inert, for example talc, lime, baryte and bentonite clay.
The foundation base component also includes at least one color pigment. Alternatively, the foundation base component contains a plurality of color pigments, both organic color pigments and inorganic color pigments. The color pigments are selected based upon the desired color in final dried paint. The color pigments are added to the foundation base material in an amount sufficient to provide the desired hiding or covering of the substrate to which the paint system is applied. More specifically, the amount of color pigments are sufficient to hide dark or multi-colored backgrounds, i.e., gray stripes on a white background, with the application of only the foundation base component and the top coat component. The color pigments are added to the foundation base component in an amount such that the volume ratio of organic color pigments to binder (Volume of Color Pigments/Volume of Binder) is at least about 0.10, preferably at least about 0.15, and more preferably at least about 0.20.
As stated above, the color pigments can be organic color pigments, inorganic color pigments or mixtures thereof. In one embodiment, the foundation base component includes at least one organic color pigment, and can contain a plurality of different organic color pigments, for example synthetic organic color pigments. Alternatively, the foundation base component includes a mixture of organic color pigments and inorganic color pigments. In this mixture, the majority of color pigments are organic color pigments. In one embodiment, the volume ratio of organic color pigments to inorganic color pigments in the foundation base component is at least about 0.5, preferably at least about 1.0, more preferably at least about 1.5, and can increase as high as desired. In fact, this ratio can be infinitely high for foundation base components that do not contain any inorganic color pigments. In general, a sufficient amount of organic color pigments are included in the foundation base component so that the organic color pigments represent at least about 8%, preferably at least about 15%, more preferably at least about 30% by volume of the dried film.
The inventive paint system also includes a top coat component that is applied over the foundation base component after it dries. The top coat component can include the same constituents, i.e., binders, diluents, color pigments and additives, as the foundation base component. The top coat component includes the same general formulation of binders, diluents and additives as the foundation base component or can include a different formulation. The top coat component can include both organic color pigments and inorganic color pigments. Suitable organic and inorganic color pigments are the same as for the foundation base component. Although the top coat component can contain both organic and inorganic color pigments, preferably, the top coat component contains primarily organic color pigments. In one embodiment, at least about 80%, preferably about 85%, more preferably about 90% by volume of all color pigments in the top coat component are organic color pigments. In addition, the ratio of organic color pigments in the foundation base component to the organic color pigments in the top coat component is at least about 2 times, preferably at least about 2.5 times, and more preferably more than about 3 times. In order to facilitate adequate hiding of the substrate while achieving the desired color in the final paint system without substantial loss in color qualities such as brightness, the foundation base component and the top coat component are formulated to be substantially the same color.
The top coat composition is preferably opaque. As used herein, the term “opaque”, in reference to substrates, coatings, compositions that are made into coatings and the like (hereinafter referred to generally as coating(s), without intent to limit), including, but not limited to, solid and/or liquid states, means that the coating has an average transmittance of visible light, e.g., between about 380 nm and about 770 nm or alternately between about 400 nm and about 700 nm, of less than about 30% on a 3-mil drawdown film, preferably at least about 20%, more preferably at least about 10%. The average transmittance referred to herein is typically measured for incident light normal, i.e., approximately 90°, to the plane of the coating and can be measured using any known light transmission apparatus and method, e.g., a UV-Vis spectrophotometer. Both the foundation paint and the top coat paint form opaque films on the substrate to be covered.
General descriptions of paints and components thereof can be found in commonly-owned, co-pending U.S. patent application Ser. Nos. 11/290,667, filed on Nov. 30, 2005, 11/323,622, filed on Dec. 30, 2005, and 11/384,183, filed on Mar. 16, 2006. These applications are incorporated by reference herein in their entireties.
Both synthetic and natural organic pigments can be used. Suitable organic color pigments include, but are not limited to, azo (monoazo, diazo, β-naphthol, naphthol AS, benzimidazolone, diazo condensation etc.), metal-complex, isoindolinone and isoindoline, phthalocyanine, quinacridone, perinone and perylene, anthraquinone, diketopyrrolopyrrole (DPP), dioxazine, quinophthalone and fluorescent pigments.
In general, the main categories of suitable organic color pigments can be classified as azo pigments and non-azo or polycyclic pigments. Suitable pigments are disclosed in U.S. Pat. No. 5,985,987, which is incorporated herein by reference in its entirety. These suitable pigments include organic pigments such as,
Other pigments include organic-inorganic hybrid pigments such as TICO pigments (commercially available from Heubach). Examples of TICO pigments are
Both synthetic and natural inorganic pigments can be used. Suitable inorganic color pigments include, but are not limited to, pigments in elementary form, i.e., carbon and aluminum, oxide and oxide hydroxide pigments, e.g., TiO2, Fe2O3 and FeO(OH), oxide mixed-phase pigments, e.g., 4BiVO43Bi2MoO6, (Co,Ni,Zb)2TiO4 and Cu(Fe,Cr)2O4, sulphide and sulphate pigments, e.g., ZnS, BaSO4 and ZnS+BaSO4, chromate and chromate molybdate mixed-phase pigments, e.g., PbCrO4+PbSO4 and PbCrO4+PbSO4+PbMoO4, complex salt pigments, for example iron blues are complex salts of ammonium and sodium ferriferrocyanides, and silicate pigments, e.g., ultramarines (Na7 Al6 Si6 O24S3).
Suitable inorganic pigments, as disclosed in the '987 patent, include
In one exemplary embodiment, a paint system in accordance with the present invention consists essentially of the foundation base component that contains at least one organic color pigment representing at least about 8% of the volume when dry, and a top coat component applied over the foundation base component and containing one or more organic color pigments at an amount of at least about 80% of all color pigments by volume, and formulated such that the ratio of organic color pigments in the foundation base component to organic color pigments in the top coat component is at least about 2.
In another innovative aspect of the present invention, the foundation base component comprises at least one low molecular weight polymer that undergoes self-crosslinking at ambient conditions during and after paint drying. The low molecular weight polymer penetrates various substrates, including chalky surfaces, to provide improved adhesion. Moreover, because the low molecular weight polymer is self-crosslinking at ambient conditions, the polymer enhances the performance of dried paints, including improving mechanical strength, weatherability, and tannin block properties.
In one embodiment, the foundation base component comprises a latex dispersion comprising at least one polymer having a relatively low molecular weight, which undergoes self-crosslinking at ambient temperatures during and after paint drying, and optionally a second polymer having a relatively high molecular weight. In an alternative embodiment, the second polymer also has a relatively low molecular weight.
As used herein, the phrase “relatively low molecular weight” means a number average molecular weight of less than about 100,000 Daltons. Also as used herein, the phrase “relatively high molecular weight” means a number average molecular weight of greater than about 100,000 Daltons, preferably greater than about 200,000 Daltons.
In one aspect of the present invention, the latex emulsion composition can comprise a polymer blend. Further discussion of latex dispersions containing polymer blends is provided in commonly-owned, co-pending U.S. patent application Ser. No. 11/384,183, filed on Mar. 17, 2006, and 12/052,808, filed on Mar. 21, 2008, both entitled “Emulsion Polymer Blend Coating Compositions and Methods for Increasing Chalky Substrate Adhesion,” which were previously incorporated by reference in their entireties.
One of the benefits of relatively low molecular weight chains in coating compositions containing the latex polymer blends according to the invention can be improved substrate adhesion, including adhesion to chalky surfaces and wood surfaces. Additionally, upon self-crosslinking at ambient conditions, the inventive low molecular weight chains enhance the performance of dried paints, including improving mechanical strength, tannin block properties, and weatherability. As discussed in U.S. Pat. No. 6,531,223, tannin blocking is the ability of a coating to prevent water-soluble chromophoric compounds, present in or on a substrate or substrate coating, from migrating through a newly applied topcoat.
One of the benefits of relatively high molecular weight chains in the latex polymer blends according to the invention can also be increased physical/mechanical strength. Combining these benefits by creating a coating composition containing a polymer blend having both relatively high molecular weight and relatively low molecular weight polymer chains is therefore desirable. More particularly, it is believed that a combination of low and high molecular weight polymers can simultaneously result in acceptable adhesion and acceptable physical/mechanical properties.
In one embodiment, the number average molecular weight of the first polymer is less than about 100,000 Daltons and the number average molecular weight of the second polymer is greater than about 100,000 Daltons. For example, for the first polymer the number average molecular weight can be from about 7,000 Daltons to about 80,000 Daltons, preferably from about 15,000 Daltons to about 60,000 Daltons. The number average molecular weight of the second polymer can be from about 100,000 Daltons to about 1,500,000 Daltons, preferably from about 200,000 Daltons to about 1,000,000 Daltons.
The glass transition temperatures of both polymers in the blend are typically above about −30° C. In a preferred embodiment, the Tg values of both polymers in the blend can fall within the range from about −20° C. to about 60° C., preferably from about −15° C. to about 50° C. In one embodiment, the Tg of the first polymer can be less than about 25° C. In a preferred embodiment, the Tg of the first polymer can be from about −15° C. to about 40° C., preferably from about −10° C. to about 30° C., for example from about −5° C. to about 20° C. or from about 0° C. to about 10° C. In another embodiment, the Tg of the second polymer can be less than about 25° C. In another preferred embodiment, the Tg of the second polymer can fall within the range from about −20° C. to about 100° C., or from about −10° C. to about 45° C., preferably from about −5° C. to about 35° C., for example from about 0° C. to about 25° C. or from about 5° C. to about 25° C. In another preferred embodiment, the Tg of the second polymer can be at least about 0° C. or at least about 80° C., preferably from about 10° C. to about 60° C. and more preferably from about 20° C. to about 40° C. Alternatively, the Tg of the second polymer is about 10° C. about 15° C., or about 20° C. greater than the Tg of the first polymer.
In one embodiment, the Tg values for each of the polymers of the blend can preferably be measured using conventional tools and techniques known to those of skill in the art, e.g., differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), or the like, or a combination thereof. In another embodiment, the Tg values for each of the polymers of the blend can be completely calculated by applying Fox's law to known Tg values, e.g., from any edition of the Polymer Handbook such as the 3rd ed. (1989), of the homopolymers corresponding to each of the monomers used and their respective weight ratios. For descriptions of this latter method, see, e.g., U.S. Pat. No. 6,723,779 and/or International Publication No. WO 94/04581, the disclosures of both of which are incorporated herein by reference in their entireties. Preferably, Fox's law is used.
In a preferred embodiment, the relative proportion of the first polymer to the second polymer in the polymer blend according to the invention can be from about 1:4 to about 2:1 by weight, for example from about 1:4 to about 4:3 by weight, preferably from about 1:3 to about 5:4 by weight, more preferably from about 1:3 to about 6:5 by weight, most preferably from about 3:7 to about 1:1 by weight.
In the polymer blend of the present invention, both polymers can be made from a mixture of constituent monomers containing (a) diluent monomers having either no functional groups or functional groups that are relatively unreactive and (b) functional (also called crosslinkable) monomers having functional groups that are relatively reactive and that are capable of crosslinking the polymer with a crosslinking agent. The functional monomers can be useful for later coalescence, and optionally crosslinking, if desired, of one or both of the polymers in the blend. As a common functional group is a carboxylic acid group, the content of the functional monomers that are not also self-crosslinking herein can be described as acid monomer content.
In one embodiment, the first polymer in the polymer blend can have a self-crosslinking monomer content from about 0.1% to about 10% by weight, preferably 0.1% to about 5% by weight, for example from about 0.2% to about 4% by weight; or from about 0.5% to about 4%; or from about 0.4% to about 3% by weight; or from about 0.5% to about 2% by weight; or from about 0.2% to about 1.5% by weight; or from about 0.2% to about 1% by weight. Suitable self-crosslinking monomers include alkoxy silanes which can crosslink at ambient conditions such as when during after paint drying. Examples of such alkoxy silanes include vinyltriethoxysilane (commercially available as SILQUEST™ A-151 from Momentive Performance Materials, Inc. of Wilton, Conn.).
In one embodiment, both of the polymers in the polymer blend can have an average acid monomer content of less than about 10% by weight, preferably less than about 7%, more preferably from about 0.1% to about 5%, for example from about 0.5% to about 3%. Although the acid content is described herein in terms of weight percent of acid monomer, acid content can be quantified in many ways, e.g., acid number.
Another group of monomers also contain reactive functional groups, but those groups are capable of crosslinking the polymer without the presence of a crosslinking agent in the composition; such monomers are collectively termed “crosslinking monomers” herein and include, but are not limited to, “self-crosslinking” monomers, which require no external crosslinking agent to form crosslinks, “oxidatively crosslinking” monomers, which utilize atmospheric oxygen but need no crosslinking agent in their composition to form oxidative crosslinks, and the like.
Many different functional groups may be suitable as pendant groups on the constituent monomers forming the polymers in the blend according to the invention. Although the polymers in the blend according to the invention can be described in terms of their acid content, it should be understood that the term “acid content” should include not merely the content of carboxylic acid-containing monomers, but the combined content of any functional/crosslinkable (but not crosslinking) monomers. Further, as used herein, the terms “polymer” and “polymers” are used to refer to oligomers, homopolymers, random copolymers, statistical copolymers, alternating copolymers, periodic copolymer, bipolymers, terpolymers, quaterpolymers, other forms of copolymers, adducts thereof, substituted derivatives thereof, and combinations or blends thereof. Such polymers can be linear, branched, hyper-branched, crosslinked, block, di-block, multi-block, graft, isotactic, syndiotactic, stereoregular, atactic, gradient, multi-arm star, comb, dendritic, and/or any combination thereof.
Examples of polymer repeat units having functional groups can include, but are not limited to, acrylic acid, ionic acrylate salts, alkacrylic acids, ionic alkacrylate salts, haloacrylic acids, ionic haloacrylate salts, acetoacetoxyalkyl acrylates, acetoacetoxyalkyl alkacrylates, polymerizable anhydrides such as maleic anhydride, acrylamide, alkacrylamides, monoalkyl acrylamides, monoalkyl alkacrylamides, wet adhesion monomers such as alkacrylamidoalkyl ethyleneureas and alkenyloxyamidoalkyl ethyleneureas, sold under the trade names Sipomer™ WAM (II), Sipomer™ WAM (IV), MONOMER QM-1458, and Cylink™ C4, and Rohamere®, vinyl dicarboxylic organic acids (e.g., itaconic acid, glutaconic acid, maleic acid, angelic acid, fumaric acid, tiglic acid, and the like), monoalkyl esters of vinyl dicarboxylic organic acids (e.g., methyl maleate, ethyl fumarate, and the like), monoisopropenyl esters of saturated, vinyl dicarboxylic organic acids, monoalkoxydialkyl vinyl silanes, dialkoxyalkyl vinyl silanes, trialkoxy vinyl silanes, monoalkoxy acrylic silanes, dialkoxy acrylic silanes, trialkoxy acrylic silanes, trialkoxy methacrylic silanes, monoalkoxy epoxy silanes, dialkoxy epoxy silanes or trialkoxy epoxy silanes, diacetone acrylamides, and the like, and copolymers and combinations thereof.
As used herein, the prefix “alk” before an ethylenically unsaturated monomer should be understood to indicate a C1-C6 hydrocarbon side group attached to either carbon of the olefinic pendant group, though it usually refers to a group attached to the same carbon as the olefinic pendant group. For example, the most basic alkacrylic acid is methacrylic acid. However, if the “alk” group is on the vinyl carbon not containing the pendant carboxylic acid, then a methacrylic acid becomes crotonic acid, which is contemplated as an alkacrylic acid, as defined herein. Another example includes tiglic acid (i.e., 2-butene-2-carboxylic acid), which is an alkacrylic acid containing two “alk” groups, with one methyl group attached to each vinyl carbon. As used herein, the term “alkyl” should be understood to mean an aliphatic C1-C18 hydrocarbon moiety. For instance, the monomer ethyl methacrylate has a methyl group attached as an ester to the pendant carboxylate group and an ethyl group attached to the same carbon of the vinyl moiety as the pendant carboxylate (i.e., CH2═C(CH2CH3)—C(═O)O(CH3)). As used herein, the term “alkenyl” should be understood to mean a C2-C18 hydrocarbon moiety having a single double bond, preferably a terminal double bond. As used herein, the term “alkoxy” group should be understood to mean a group having a C1-C12 hydrocarbon or oxyhydrocarbon (i.e., containing hydrogen, carbon, and oxygen atoms) moiety attached to a terminal oxygen atom.
In addition to the monomers containing functional groups, both the polymers in the blend according to the invention can also comprise diluent monomers or repeat units that contain pendant groups that do not typically react with crosslinking agents. Examples of such diluent monomers can include, but are not limited to, alkyl acrylates, alkyl alkacrylates, alkyl esters of vinyl monocarboxylic organic acids other than acrylates and alkacrylates (e.g., ethyl tiglate, methyl crotonate, and the like), dialkyl esters of vinyl dicarboxylic acids, styrene, alkylstyrenes (e.g., α-ethylstyrene, α-methylstyrene, vinyl toluene, 2,4-dimethylstyrene, 4-t-butylstyrene, and the like), halostyrenes (e.g., α-bromostyrene, 2,6-dichlorostyrene, and the like), isopropenyl esters of saturated, monocarboxylic organic acids (e.g., isopropenyl acetate, isopropenyl isobutyrate, and the like), monoisopropenyl monoalkyl esters of saturated, dicarboxylic organic acids (e.g., isopropenyl alkyl oxalate, isopropenyl alkyl succinate, and the like), vinyl carboxylate alkyl ethers (e.g., vinyl acetate, vinyl propionate, vinyl butyrates, vinyl benzoates, halo-substituted versions thereof such as vinyl chloroacetate, and the like), vinyl alkyl ethers, acrylonitrile, alkacrylonitriles, dialkyl acrylamides, dialkyl alkacrylamides, allyl compounds (e.g., allyl chloride, allyl esters of saturated, monocarboxylic acids, allyl alkyl esters of saturated, dicarboxylic organic acids, and the like), and the like, and combinations thereof. Preferred diluent monomers include, but are not limited to, C1-C8 alkyl acrylates, C1-C8 alkyl C1-C2 alkacrylates, styrene, C1-C4 alkylstyrenes, vinyl acetate, and combinations thereof.
In one embodiment, both the polymers in the blend according to the invention can be substantially acrylic. As used herein, the term “acrylic” refers to (co)polymer compositions made from monomers selected from the group consisting of alkyl acrylates, alkyl alkacrylates, acrylic acid, ionic acrylate salts, alkacrylic acids, ionic alkacrylate salts, acrylamide, alkacrylamides, monoalkyl acrylamides, monoalkyl alkacrylamides, acrylonitrile, alkacrylonitriles, substituted versions thereof (e.g., hydroxyalkyl acrylates, hydroxyalkyl alkacrylates, alkacrylamidoalkyl ethyleneureas, alkenyloxyamidoalkyl ethyleneureas, and the like), and the like, and combinations thereof. As used herein, the term “substantially,” at least with regard to a component in a composition, means that the composition contains at least about 90% by weight of that component, preferably at least about 95% by weight of that component, more preferably at least about 97% by weight of that component, most preferably at least about 99% by weight of that component, in some cases at least about 99.9% by weight of that component, or completely comprises (about 100% by weight of) that component.
The present invention also contemplates other methods for improving adhesion of paint compositions applied on chalky substrates, including for example, formulating latex compositions comprising alkyd resins. Another method relates the formation of latex polymers having multimodal molecular weight distributions. Multimodal molecular weight distributions are typically attained by sequentially polymerizing monomers and by using a molecular weight control agent, such as a chain transfer agent, at some point during the polymerization process. See, e.g., commonly-owned, co-pending U.S. patent application Ser. No. 11/323,621, filed Dec. 30, 2005, and entitled “Emulsion Polymers Having Multimodal Molecular Weight Distributions,” which is incorporated herein by reference in its entirety. As discussed in the '621 application, the acrylic latex composition disclosed therein comprises polymer particles having a multimodal molecular weight distribution comprising at least a first, distinct, higher molecular weight peak and a second, distinct, lower molecular weight peak. Advantageously, the polymer particles can have a total number average molecular weight of not more than about 60,000 Daltons, a total weight average molecular weight of not less than about 150,000 Daltons, and a polydispersity of at least about 3.1. Also advantageously, (a) the first, distinct, higher molecular weight peak can have a peak molecular weight from about 175,000 Daltons to about 400,000 Daltons; (b) the second, distinct, lower molecular weight peak can have a peak molecular weight from about 15,000 Daltons to about 60,000 Daltons; (c) the ratio of the peak molecular weights between the first peak and the second peak can be from about 3:1 to about 30:1; and (d) the polymer particles (i) can be substantially free from hydroxy-functional monomer repeat units and conjugated diene monomer repeat units, (ii) can comprise substantially acrylic monomers, or (iii) both (i) and (ii).
In yet another aspect of the present invention, chalky substrate adhesion of paint compositions can be improved by formulating a latex composition comprising sequentially polymerized polymer particles. See, e.g., commonly-owned, co-pending U.S. patent application Ser. No. 11/774,226, filed Jul. 6, 2007, and entitled “Emulsion Polymers Having Increased Chalky Substrate Adhesion,” which is incorporated herein by reference in its entirety. The sequentially polymerized polymer particles are formed in at least two polymerization stages so as to form a first phase polymer, which results from a first polymerization stage, and a second phase polymer, which results from a second polymerization stage. The first phase polymer is made from a first set of constituent monomers, has a number average molecular weight greater than about 100,000 Daltons. and the second phase polymer is made from a second set of constituent monomers, has a number average molecular weight less than about 100,000 Daltons polymer or vice versa. Optionally, the first and/or the second phase polymer comprise at least one crosslinkable monomer.
The present invention is also directed to methods for covering substrates using paint systems formulated in accordance with the present invention. Suitable substrates include, but are not limited to, metals, such as steel, iron and aluminum, and plastics, such as thermoplastics, like polycarbonates, polyacrylates and especially thermoplastic polyolefins, papers, wood and wood products, cardboard, plaster, dry-wall or plasterboard and combinations thereof. The paint system can be applied to the substrate using any suitable method known and available in the art including, brushing, rolling and spraying. In one embodiment, a single coat or layer of a foundation base component formulated in accordance with the present invention is applied to the substrate. The foundation based component can be allowed to partially or completely dry. A single coat or layer of the top coat component formulated in accordance with the present invention is then applied over the foundation base component.
The following Examples are merely illustrative of certain embodiments of the invention. The following Examples are not meant to limit the scope and breadth of the present invention, as recited in the appended claims.
A one gallon aluminum can was filled with Benjamin Moore Details Eggshell 5244X (115 oz.) and Benjamin Moore Details Colorant 229Y1(Organic Yellow) (15 oz.). The formulation was mixed in a mechanical shaker for about 6 minutes. Using a 3-mil drawdown bar, a drawdown was applied onto a black and white Leneta drawdown card (Form 18B). A drawdown is the application of paint evenly to a card such as Leneta drawdown cards. In this Example, Form 18B is a black and white card comprising four areas: two sealed white areas, one unsealed white area and one sealed black area Form 18B is a penopac chart, which measures opacity and penetration. Leneta cards are known in the art. In all the Examples discussed herein Form 18B is used as the substrate.
The drawdown was dried overnight and the contrast ratio (C/R) of the dried film was measured with a spectrophotometer. A second drawdown was then made on the top of the first coat to obtain the C/R of the two-coat dry film. Third and fourth drawdowns were also made, and the corresponding C/Rs of the three-coat and four-coat dry films were determined. The C/Rs of the one-coat, two-coat, three-coat, and four-coat dry films are shown in
As shown in
A color foundation finish (100 gallons) was prepared using the following quantities of grind and letdown ingredients:
In Example 2, no inorganic color pigment is used and the organic color pigments represent 11.7 vol % of the foundation paint and 30.8 vol % of the dried foundation film.
The C/R on a 3-mil drawdown was measured for one coat of color foundation Example 2, and for one coat of Example 2 plus a top coat of Example 1. As shown in
A color foundation finish (100 gallons) was prepared using the following quantities of grind and letdown ingredients:
In Example 3, no inorganic color pigment is used. The organic color pigments represent 19.3% by volume of the foundation paint and 42.5% of the dried film. The C/R of the foundation coat on a 3-mil drawdown is 99%.
A yellow pigment paste was prepared using the following ingredients:
In a separate container, a color foundation finish (100 gallons) was prepared using the following quantities of grind and letdown ingredients:
In Example 4, the organic to inorganic color pigment ratio is 2.49 by volume. The organic color pigments represent 17.9% by volume of the foundation paint and 35.0% of the dried film. The C/R of a 3-mil drawdown of Example 4 is 99.2%.
Conventional color primers using titanium dioxide have a “whitening effect” because only a small amount of color pigments, especially organic color pigments, are used in the tints. The color foundation in Example 4 uses a large amount of organic color pigments that overcome the whitening effect from titanium dioxide. It is a tintable yellow foundation finish that can be tinted to many different shades required by top coats. Table 1 shows this yellow foundation finish of Example 4 (124 oz.) tinted with various BM Details Colorants (4 oz.).
The color foundation coat uses a significantly larger amount of organic pigments than those in a conventional first coat and at least twice as many organic pigments by volume than the top coat. Table 2 lists the organic pigment levels in the conventional first coat, color foundation coat, and top coat.
Color foundation coat/top coat paint systems (with the colors of Yellow (BM color palette 2023-10) and Bright Lime (BM color palette 2025-10)) were compared with conventional approaches using two top coats of BM Details, C2 commercial color primer with a top coat, and BM Deep Base Primer (216) with Benjamin Moore Regal top coat (319). The paints using conventional approaches were obtained from Benjamin Moore and C2 retail stores.
The following components were used in the first and second coats of Example 5A:
The following components were used in the first and second coats of Example 5B:
For Example 5C, the first coat contained a Color Primer Accent Color System (C2085) tinted to BM Color 2025-10 at a C2 retail store (see www.C2color.com). The second coat (top coat) contained a C2 Interior Eggshell Acrylic Enamel (C4285) tinted to BM Color 2025-10 at a C2 retail store.
For Example 5D, the first coat contained a BM Regal Deep Base Primer 216 tinted to color P702 in BM Color palette as a recommended primer. The second coat (top coat) contained BM Regal 319 4B tinted to BM Color 2025-10.
In Example 5D, the organic color pigment volume for the first coat is 1.6% in paint and 6.16% in dried film. The organic color pigment volume for the second coat is 2.17% in paint and 5.70% in dried film.
For Example 5E, two coats of BM Details Eggshell were tinted to BM Color 2023-10 as in the second coat of Example 5A. In example 5E, the organic color pigment volume is 1.78% in paint and 4.23% in dried film.
For Example 5F, two coats of BM Details Eggshell were tinted to BM Color 2025-10 as in the second coat of Example 5B. In Example 5F, the organic color pigment volume is 1.77% in paint and 4.21% in dried film.
A contrast ratio of at least 99%, or preferably 99.5%, for two or more coats of certain bright and high chroma colors, is required to have hiding power on black/white substrate without being detected by trained eyes. Examples of these bright and high chroma colors are organic yellow and other light colors tinted from organic yellow, such as light orange and light blue.
Conventional approaches, such as Examples 5E and 5F, would need more than two 3-mil thick coats to have the required hiding power on black/white substrate of Form 18B. Two-coat paints of a conventional primer and a top coat, such as Example 5C in which the primer basically has about the same organic pigment content as in the top coat, also would not have adequate hiding power on black/white substrate.
Other conventional approaches include adding high hiding power color pigments (e.g., dark green, blue, black or some other dark color pigments in the primer as the first coat. For example, a better hiding organic pigment, such as green is used in Example 5D to improve hiding. Although the C/R is sufficient to hide black/white substrate, the difference between the color of primer and top coat is increased. Consequently, one top coat is not sufficient to hide the color of the underlying primer so as to obtain the desired color.
For Color 2023-10, the Delta E value between the color foundation/top coat paint system (from Example 5A) and two same-colored top coats (from Example 5E) is 0.12 as shown in
In order to achieve such a close match, the reflectance curve of the color foundation coat and the reflectance curve of the foundation and top coat should have a similar pattern.
When paint films are applied using brushes or rollers, the paint films are not as smooth as in drawdowns. Brush marks from brushes or bumps form rollers may be formed. The color of the primer, which has a very different color than the top coat, may not only be seen through the top coat but also may have a non-uniform appearance. Additional one or more top coats are required to have the right and uniform color.
A conventional color finish was formulated using the following ingredients:
A tintable red color foundation, which contains both inorganic pigment (TiO2) and red organic pigment, was prepared using the following quantities of grind and letdown ingredients:
The contrast ratios (C/Rs) of Examples 6 and 7, measured on a Leneta card, are listed in Table 4. Two coats of conventional Example 6 have a C/R of 93% and will not have sufficient hiding power to hide black/white substrate. The red foundation of Example 7 with a top coat improves the C/R to 99.8%.
Example 7 is a tintable red foundation finish that can be tinted with color concentrates to obtain desired colors. In Table 5, Example 7 (124 oz.) was tinted with various Benjamin Moore Details Color Concentrates (4 oz.). The C/Rs were measured on a 3-mil draw-down.
C2 Primer (C2085) and C2 Interior Acrylic Eggshell Enamel (C4284) were obtained from a C2 retail store and tinted to the Color 2000-10 in Benjamin Moore Color Palette.
A Deep Base Primer 216 tinted to the Color P-500 in BM Color Palette was used as the first coat. Benjamin Moore Regal Eggshell was tinted to 2000-10 was used as the second coat. The following components were used in the first and second coats of Example 8B:
For example 8C, the red color foundation of Example 7 was used as a first coat. Benjamin Moore Details Eggshell 524 was tinted to 2000-10 and was used as second coat. The following components were used in the first and second coats of Example 8C:
The C/Rs were measured on dried drawdowns using a 3-mil drawdown bar, and are listed in Table 6. The color foundation/top coat was the only paint system that provided adequate hiding for two coats. C2 paints with three coats still did not provide sufficient hiding power.
The color difference between the red foundation coat/top coat (Example 8C) and the same two top coats has a Delta E of 0.26. This small Delta E is reflected in the reflectance curves in
C* is the distance of a color in the color space to the center. It is a measure of the chroma of a color. A large value of C* indicates a high chroma color, or a clean color as referred to in the paint industry. Organic pigments typically provide higher chromatic colors than inorganic pigments of the same colors. Organic yellow and red pigmented paints may have C* of at least 70 and well over 100, depending on the amount and type of other color or extender pigments in paints.
C* of color foundation/top coat systems and multiple top coats were measured with a spectrophotometer on dried films. As shown in Table 7, the C* of a color foundation/top coat system is almost identical to that of multiple top coats of same colors. The color foundation/top coat system retains the high chroma of those colors from organic color pigments. In addition, the L is the indication of the brightness of a color. Table 7 shows that the brightness of the color is not decreased by the foundation coat.
For the Examples below, color pigment concentrates were made prior to color foundation finishes, because most of the color concentrates from organic color pigments require high speed mixing and sand milling. Example 10 describes the formulation of a yellow color pigment concentrate, and Example 11 describes the formulation of a red color pigment concentrate.
A yellow color pigment concentrate was formulated using the following quantities of ingredients listed, in order of addition, in Table 8.
A red color pigment concentrate was formulated using the following quantities of ingredients listed, in order of addition, in Table 9.
Example 12 describes a low molecular weight, low glass transition temperature polymer formed with 0.9 wt % of a self-crosslinking monomer present in the constituent monomers. The number average molecular weight of the polymer of Example 12 was found to be about 34,000 Daltons and the weight average molecular weight was about 95,000 Daltons by gas permeation chromatography. The glass transition temperature of the polymer of Example 12 was calculated to be about −5° C. The latex polymer formulation, in order of addition, is described below in Table 10.
Example 13 describes a yellow color foundation finish made with the polymer of Example 12 and the yellow color pigment concentrate of Example 10. The paint composition, in order of addition, is described in Table 11.
Example 14 describes a yellow color foundation finish made with a yellow pigment concentrate from Example 10 and Rhoplex® PR-33 (commercially available from Rhom & Haas Company), which is a latex polymer that will undergo a crosslinking reaction at ambient conditions when paints are dried. The Rhoplex® PR-33 polymer has a number average molecular weight of about 12,000 Daltons and a weight average molecular of about 65,000 g/mol as determined by gas permeation chromatography, and a glass transition temperature of about 1° C. by Differential Scanning Calorimetry. The paint composition, in order of addition, is described in Table 12.
Example 15 describes a red color foundation finish made with the red color pigment concentrate of Example 11 and Rhoplex® PR-33, which as discussed above is a low molecular weight and self-crosslinkable polymer. The paint composition, in order of addition, is described in Table 13.
Example 16 describes a yellow color foundation finish made with the yellow Gennex Waterborne™ colorant and a blend of Rhoplex® PR-33 and a conventional latex polymer. The conventional latex has a relatively high number average molecular weight of greater than about 200,000 Daltons and a glass transition temperature of about 6° C. The paint composition, in order of addition, is described in Table 14.
Example 17 describes a red color foundation finish made with the red color pigment concentrate of Example 11 and a blend of Rhoplex® PR-33 and a conventional latex polymer. The paint composition, in order of addition, is described in Table 15.
The color foundation paints of Examples 13-17 were tested for contrast ratio, wet adhesion, and chalk binding. The results of these three tests are presented below in Table 16.
The wet adhesion test was performed on glossy alkyd panels, which are substrates of high gloss paints (IMPERVO® Alkyd High Gloss Metal & Wood Enamel Wet Adhesion Paint) that were dried in an oven at 120° F. for 24 hours. Various 3-mil thick drawdown coatings of the inventive aqueous paint compositions were applied to the glossy alkyd panels and let dry for about 7 days at ambient conditions. After drying, the coated panels were placed in a fog box, simulating rain conditions at 100% humidity, for about 4 hours and were dried in air at ambient conditions for about 1 hour prior to the Cross-hatch Adhesion test using Scotch™ 600 tape, as detailed in ASTM D3359 Method B. The percentage of peeling (area) for each Example is recorded in Table 16, and, as shown therein, is 0% for each Example.
Chalk binding tests are typically performed on chalky substrates. Chalky substrates are commercial alkyd paints that have been naturally weathered to achieve an ASTM chalk ratings of about 5. A suitable test method is described in U.S. Pat. No. 6,268,420.
In these cases, chalky substrates are western red cedar panels painted with commercially available alkyd paints and weathered to have ASTM ratings of 5 using the method described in the '420 patent. Various 3-mil thick draw down coatings of paint compositions were applied to these panels and let dry for about 7 days at ambient conditions. After drying, the coated panels were also placed in a fog box as in wet adhesion test, and were dried in air at ambient conditions for about 1 hour prior to the cross-hatch adhesion test using Scotch™ 600 tape. The results were evaluated in the same way as in the wet adhesion test. The percentage of peeling (area) for each Example is recorded in Table 16, and, as shown therein, is 0% for each Example.
A color foundation coat/top coat paint system was developed for Benjamin Moore Color Yellow 2015-20. The yellow color foundation paint from Example 16 was used as the foundation coat, and Benjamin Moore Aura Interior Paint 5244X was used as the top coat. Table 17 lists the components used in the foundation coat and top coat of Example 18.
A color foundation coat/top coat paint system was developed for Benjamin Moore Color Red 2001-10. The red color foundation paint from Example 17 was used as the foundation coat, and Benjamin Moore Aura Interior Paint 5244X was used as the top coat. Table 18 lists the components used in the foundation coat and top coat of Example 18.
The color foundation coat uses a significantly larger amount of organic color pigments than a conventional coat, such as the top coat, and uses at least twice as much of organic pigments by volume than in the top coat. Table 19 below lists the organic color pigment levels in the color foundation coat and top coat of the dried film. More particularly, for both Example 18 and Example 19, Table 19 lists the organic color pigment volume % and organic color pigment/binder volume ratio.
C* is the distance of a color in the color space to the center. It is a measure of the chroma of a color. A large value of C* indicates a high chroma color, or a clean color as referred to in the paint industry. Organic pigments typically provide higher chromatic colors than inorganic pigments of the same colors. Organic yellow and red pigmented paints may have C* of at least 70 and well over 100, depending on the amount and type of other color or extender pigments in paints.
C* of color foundation/top coat systems and multiple top coats were measured with a spectrophotometer on dried films. As shown in Table 20, the C* of a color foundation/top coat system is almost identical to that of multiple top coats of same colors. The color foundation/top coat system retains the high chroma of those colors from organic color pigments. In addition, the L is the indication of the brightness of a color. Table 20 shows that the brightness of the color is not decreased by the foundation coat.
While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives of the present invention, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Additionally, feature(s) and/or element(s) from any embodiment may be used singly or in combination with other embodiment(s) and steps or elements from methods in accordance with the present invention can be executed or performed in any suitable order. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention.
This application is a continuation-in-part of U.S. patent application Ser. No. 11/470,817, filed Sep. 7, 2006, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11470817 | Sep 2006 | US |
| Child | 12235117 | US |
