Vinyl-acrylic coating compositions with reduced tint strength drift

Abstract

Disclosed herein are aqueous architectural compositions comprising an opacifying pigment, and a copolymer polymerized from at least one vinyl monomer and at least one meth(acrylate) monomer, wherein the at least one vinyl monomer makes up from about 70 wt. % to about 90 wt.% of all monomer weight. The aqueous architectural compositions also include a tristyryl phenol ethoxylate phosphate surfactant and a dispersant. The dispersant includes a styrene-maleic acid copolymer dispersant, or a hydrophobic copolymer dispersant, or both.

Description

Docket No. BJM-136. PCT VINYL-ACRYLIC COATING COMPOSITIONS WITH REDUCED TINT STRENGTH DRIFT FIELD OF THE INVENTION

[0001] The present invention solves a drawback with architectural coating compositions, such as paints and stains, made with vinyl-acrylic latex binder that are known to have tint strength drift caused by flocculation of opacifying pigment while the architectural coating compositions are in storage by adding a combination of surfactant and dispersant.BACKGROUND OF THE INVENTION

[0002] Paint comprises a film-forming continuous phase component that may be aqueous or solvent based, which contains a polymer resin or binder. Pigments are particulate compounds which can be dispersed in the polymer resin or polymer binder in paints to provide hiding power and to provide color to paints and coatings. Pigments may also improve the durability and weathering properties, provide opacity and special effects (e.g., flip, sparkle), and modify flow and application properties. Pigments in a dry powder form can be dispersed into the film-forming continuous phase component in a grind, i.e., suspended in an aqueous solution and dispersants, or in a colorant liquid composition. Heavy pigment particles are separated from one another and evenly distributed throughout paint compositions as a colloidal suspension.

[0003] After applying a paint or stain to a substrate and forming a paint film on the substrate, pigments in the paint or stain prevent light from passing through the film to the layer(s) below on the substrate and back to the eye of an observer. Pigments do this by absorbing and scattering light. The hiding power or opacifying power of a paint can be expressed by the number of square meters covered by 1 liter of paint to produce complete hiding. The hiding power of a pigment can be expressed by the number of square meters covered by a kilogram of pigment, which has been dispersed in a paint and applied so that it will hide the color of any previous layer. Titanium dioxide (TiO2) pigments have excellent hiding power, because their refractive indices are high and because they have the optimum particle size for maximum hiding power. For example, rutile titanium dioxide white has a particle diameter of 200 nm - 300 nm. However, titanium dioxide can be transparent when present in the form of large clusters, and its hiding power is reduced significantly when agglomerated, due to reduced light scattering efficiency. On the other hand, good dispersion increases the hiding efficiency of titanium dioxide. In order to maximize the hiding power of a paint composition. I -Docket No. BJM-136. PCT with titanium dioxide pigment, a dispersing agent should be used to prevent titanium dioxide particles from agglomerating during paint storage.

[0004] Since titanium dioxide is an expensive component, various attempts have been carried out to increase the hiding efficiency of titanium dioxide and reduce the amount of titanium dioxide as a hiding or opacifying pigment in a paint composition. US 5,385,960 to Emmons et al., US 6,080,802 to Emmons et al., US 2012 / 0058277 to Bohling et al., and US 2012 / 0058278 to Bohling et al. disclose polymer latex particles that are adsorbed directly to the surface of titanium dioxide particles to achieve optimal spacing between titanium dioxide particles.

[0005] Commonly owned US 8,895,658 to G. Dandreaux, K. Scanlon, R. Sheerin and A. Brewer teaches a grafted dispersing polymeric additive that adsorbs to the TiO2pigment to improve their spacing to optimize hiding power. The ‘658 patent utilizes tint strength of the paint films formed by the coating compositions to show pigment spacing optimization.

[0006] A significant portion of architectural coatings commercially sold to customers utilizes vinyl acrylic latex resin as the polymeric resin or binder. Vinyl acrylic resin has some advantages over the other copolymer resins, such as all acrylic latex binders or substantially all acrylic latex resins or binders; however, it has been observed that vinyl-acrylic paints lose tint strength while being stored in paint containers. Without being bound to any particular theory, the present inventors believe that vinyl acrylic latex tends to hydrolyze causing a fluctuation in the pH of the coatings which causes pigment flocculation and a loss of tint strength, known as tint strength drift.

[0007] As disclosed in the commonly owned US ‘658 patent, tint strength is a measure of how well titanium dioxide can add whiteness to a tinted paint. In one tint strength test, two ounces of colorant are added to 126 ounces of paint. Three mil drawdowns are made and allowed to dry overnight. Both an experimental and a control paint are tested. The tint strength of the experimental relative to the control is determined by measuring the reflectance of the control and experimental drawdowns with a Gretag Macbeth Color Eye 2145, and then determining base tint strength using the software of the Color Eye 2145. Tint strength can be employed as an indication of flocculation of pigments or how well the pigments are kept from flocculating to each other.Docket No. BJM-136. PCT

[0008] Conventional aqueous vinyl-acrylic paints include aliphatic phosphate surfactants and acrylic-type dispersants as additives. However, such surfactant and dispersant combinations have not achieved rheological stability and has not mitigated the tint strength drift issue.

[0009] Hence, there remains a need for vinyl-acrylic coating compositions with reduced tint strength drift.SUMMARY OF THE INVENTION

[0010] The present invention comprises several embodiments of architectural compositions, including paints and stains, utilizing vinyl-acrylic copolymer resins that exhibit reduced tint strength loss by adding a combination of selected surfactant and selected dispersant(s) described herein. These vinyl-acrylic architectural compositions have improved tint strength retention while being stored in containers, shown by experimentations. A preferred surfactant comprises a tri styryl phenol ethoxylate phosphate surfactant. A preferred dispersant comprises a styrene-maleic acid copolymer dispersant. Another preferred dispersant comprises a hydrophobic copolymer dispersant, including hydrophobic acrylic dispersant and hydrophobic polycarboxylate dispersants.

[0011] An embodiment of the present invention is directed to an aqueous architectural composition comprising an opacifying pigment, a copolymer polymerized from at least one vinyl monomer, preferably a vinyl acetate or vinyl neodecanoate, and at least one meth(acrylate) monomer, preferably a hydrophobic meth(acrylate) monomer, wherein the at least one vinyl monomer makes up from about 70 wt.% to about 90of all monomer weight, a tristyryl phenol ethoxylate phosphate surfactant from about 0.5 v.% to about 8.0 wt.%, more preferably from about 0.6 wt.% to about 7.5 wt.%, more preferably from 0.7 wt.% to about 7wt.% of the aqueous architectural composition, and a styrene-maleic acid copolymer dispersant from about 0.3 wt.% to about 8.0 wt.%, more preferably from about 0.4 wt.% to about 7.0 wt.% of the aqueous architectural composition. The wt.% of the surfactant or the dispersant is a weight of active ingredient(s) in the surfactant or the dispersant divided by a combined weight of the opacifying pigment(s) and extender pigment(s).

[0012] Preferably, the tristyryl phenol ethoxylate phosphate surfactant comprises a neutralized tristyryl phenol ethoxylate (14EO) phosphate with mono-, di-, tri- and tetra species. Preferably, the styrene-maleic acid copolymer dispersant comprises a neutralized poly(isobutylene-alt-maleic anhydride) dispersant.

[0013] Another embodiment of the present invention is directed to an aqueous archi tectural composition comprising an opacifying pigment, a copolymer polymerized from at least oneDocket No. BJM-136. PCT vinyl monomer, preferably a vinyl acetate or vinyl neodecanoate, and at least one meth(acrylate) monomer, preferably a hydrophobic meth(acrylate) monomer, wherein the at least one vinyl monomer makes up from about 70 wt.% to about 90 wt.% of all monomer weight, a tristyryl phenol ethoxylate phosphate surfactant from about 0.5 wt.% to about 8.0 wt.%, more preferably from about 0.6 wt.% to about 7.5 wt.%, more preferably from 0.7 wt.% to about 7wt.% of the aqueous architectural composition, and a hydrophobic copolymer dispersant, including hydrophobic acrylic dispersant and hydrophobic polycarboxylate dispersants, from about 0.5 wt.% to about 2.0 wt.%, preferably from about 0.75 wt.% to about 1.75 wt.%, more preferably from about 1.0 wt.% to about 1.5 wt.%. The wt.% of the surfactant or the dispersant is a weight of active ingredient(s) in the surfactant or the dispersant divided by a combined weight of the opacifying pigment(s) and extender pigment(s).

[0014] Preferably, the tristyryl phenol ethoxylate phosphate surfactant comprises a neutralized tristyryl phenol ethoxylate (14EO) phosphate with mono-, di-, tri- and tetra species. Preferably, the hydrophobic copolymer dispersant, including hydrophobic acrylic dispersant and hydrophobic polycarboxylate dispersants, comprises a sodium or ammonia salt of the dispersant.

[0015] Preferably, the opacifying pigment is titanium dioxide.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Typically, an aqueous latex paint is prepared in two steps. In the grind stage, pigments, dispersants, surfactants and water, along with other additives are added to a vessel and mixed at high speed. During this step, pigment agglomerates are broken down into its nascent particle size. Once pigment agglomerates are broken down, they need to be stabilized against re-agglomeration or flocculation. That stability is provided by dispersants, such as the commercially available Tamol™ dispersants which are low molecular weight, acid functional copolymers, and / or surfactants. These materials are available both as neutralized and un-neutralized. These polyacid dispersants are believed to adsorb onto the pigment particles’ surface to electrostatically stabilize the pigment particles to minimize pigment agglomeration. In the letdown stage, the grind is mixed with an aqueous latex resin and other additives, such as surfactants, thickeners, defoamers, biocides, etc. to make paints or stains.Docket No. BJM-136. PCT

[0017] To maximize scattering from titanium dioxide particles, they are preferably spaced at least one diameter in distance from each other. The typical diameter of a particle of titanium dioxide is about 250 nm. For vinyl-acrylic paints and stains, after the paints and stains are manufactured and stored in containers for distribution and sales, re-agglomeration or flocculation can occur due to vinyl-acrylic’s tendency to hydrolyze and cause the pH of the paints and stains to fluctuate.

[0018] As discussed in J. Koleske, R. Springate and D. Brezinski, “Additives Reference Guide” (2013) available at https: / / www.pcimag.com / ext / resources / PCI / 2013 / June / Additives-Reference-Guide-2013.pdf, (hereinafter Koleske), which is incorporated herein by reference in its entirety, dispersants, also known as deflocculants, increase the stability of pigments suspended in water. Koleske reports that dispersing pigment is a most difficult step in paint manufacturing due to the difference in surface tension between liquids (polymers and solvents) and solids (pigments and extenders). Dispersants are adsorbed onto the pigment particles and hinder the particles from approaching each other by charge repulsion effects (ionic dispersants) or by steric effects (nonionic effects). Some surfactants can act as dispersants.

[0019] Steric stabilization is the process wherein adsorbed nonionic surfactants or polymers produce strong repulsion between pigment particles in a dispersion. This produces an adsorbed layer with a thickness δ which is strongly hydrated by water in the architectural coatings when the surfactants and polymers are highly soluble in water. When the pigment particles of radius R approach to a surface-to-surface separation of less than 2δ, the adsorbed layers can overlap or be compressed resulting in a strong repulsion. As used herein, dispersants are used to suspend opacifying or extender pigment solid particles in an aqueous phase, and dispersants wet the solid particles and interact with the dispersing aqueous phase.

[0020] Koleske defines surfactants or surface-active modifiers as additives that when added to water or other liquids alter the properties of the liquid when the liquid comes into contact with another liqui d, solid or gas. Surfactants alter the interfacial characteristics of the liquid. Surfactants are added to paints and stains for various purposes, such as slip and scratch resistance, preventing craters, fisheyes and pin holes on paint films. Surfactants reduce surface tension, improve wetting and spreading as wetting agents, and aid in dispersion of pigments as dispersants.

[0021] Surfactants have a hydrophilic portion or head and a hydrophobic portion or tail. Usually, the hydrophobic tail comprises long-chain hydrocarbons, straight, branched or cyclicDocket No. BJM-136. PCT hydrocarbons, or aromatic hydrocarbons with or without alkyl side groups. The hydrophilic head contains groups such as hydroxyl, carboxyl, sulfonate, sulfate and the like, or a short ethylene oxide chain. Surfactants preferentially concentrate at interfaces, where one continuous phase ends and another begins. Surfactants lower the total energy associated with the boundary and stabilize it. Surfactants modify the properties of liquid-liquid, liquid-gas, and liquid-solid interfaces by changing the interfacial tension. Surfactants decrease the surface tensions aqueous systems such as waterborne coatings. When acting as dispersants for pigments, the hydrophobic portion of surfactants interact with the pigments and the hydrophilic portion interact with the water phase.

[0022] As used herein, dispersants are additives that adsorbed onto opacifying or extender pigments to disperse them, and surfactants are additives that perform other functions in the architectural coatings, including but not limited to reducing surface tensions at the interface. Some surfactants function as dispersants and are referred to as dispersants.

[0023] The conventional methodology for minimizing pigment flocculation has not performed well for vinyl-acrylic paints. Continuing tint strength drift in vinyl-acrylic paints, particularly when contained in paint containers, indicating pigment flocculation in vinylacrylic paints is a continuing problem.

[0024] In one embodiment, the present inventors have developed a combination of (i) a tristyryl phenol ethoxylate phosphate surfactant and (ii) a polymeric anionic dispersant to be admixed to the vinyl-acrylic paint compositions for steric stabilization of pigments, as shown below.

[0025] Tristyryl phenol ethoxylate phosphate surfactant have the following structureTristyryl phenol ethoxylate phosphate surfactant may exist in as a Gemini surfactant. Gemini surfactants possess more than one group of hydrophobic tail and a hydrophilic head are described in S. K. Hait et al, " Gemini Surfactants: A Distinct Class of Self-AssemblingDocket No. BJM-136. PCT Molecules," Current Science, Vol. 82, No. 9, 10 May 2002, which is incorporated herein by reference in its entirety. Since the Gemini version has the same active moieties as the tristyryl phenol ethoxylate phosphate surfactant, it is expected to function in a similar manner.

[0026] In another embodiment, the tristyryl phenol ethoxylate phosphate surfactant is paired with certain conventional dispersants, such as certain Tamol™ dispersants. These particular dispersants are known as hydrophobic copolymer dispersants, including hydrophobic acrylic dispersants and hydrophobic polycarboxylate dispersants. This combination also improves the loss of tint strength.

[0027] Tamol ™ dispersants have been described as polyacrylic anionic dispersants, homopolymers and copolymers of maleic acid with styrene and diisobutylene.

[0028] The preferred tristyryl phenol ethoxylate phosphate surfactant include, but are not limited to, surfactants with tristyryl phosphate ethoxylate, preferably a neutralized tristyryl phenol ethoxylate (14EO) phosphate with mono-, di-, tri- and tetra species. The neutralizing agent includes 2-amino-2-ethylpropanediol. This surfactant is also known as 2,4,6-tris(l -phenylethyl) polyoxyethylenated phosphates or poly aryl phenols, ethoxylated, phosphoric acid esters (80% active), CAS No. 90093-37-1 or 114535-82-9. Its number average molecular weight (Mn) is about 1,030 Daltons and its weight average molecular weight (Mw) is about 1208 Daltons. Its Mz (centrifugation) is about 1365 and its pH is about 4.5.

[0029] Without being bound to any particular theory, the present inventors believe that the phosphate moiety in the tristyryl phenol ethoxylate phosphate surfactant disperses TiO2in vinyl-acrylic paint systems.

[0030] This tristyryl phenol ethoxylate phosphate surfactant is commercially available as SILCO CT-1118. Surfactants with the same CAS number marketed as Solvay’s Soprophor 3D33, Primesurfs POSU 62, Stepan’s Stepfac TSP-PE, 98% active tristyrylphenol ethoxylated (PEI 6), and Clairant’s Dispersogen LFH, 96% active tristyrylphenol ethoxylated (PEI 6) are not neutralized, and can be used in the present invention after neutralization, as discussed above.

[0031] Suitable polymeric anionic dispersants include, but are not limited to, styrene-maleic acid copolymers, or neutralized poly(isobutylene-alt-maleic anhydride) copolymers. This dispersant has a weight averaged molecular weight of 15 kDa, at 38% active, pH of 8.8 (5% in water) and viscosity of about 750 mPas at 21 °C. This dispersant is commercially available as Surfynol CT-151. This dispersant improves the solubility of the neutralized tristyryl phenol ethoxylate phosphate.Docket No. BJM-136. PCT

[0032] Suitable conventional dispersants include, but are not limited to, polyacrylic anionic dispersants, homopolymers and copolymers of maleic acid with styrene and diisobutylene. As shown below, certain Tamol™ dispersants when used with the tristyryl phosphate ethoxylate surfactant show a reduction in tint strength drift. These dispersants are low molecular weight, acid functional polymers, and preferably are ammonia or sodium salt of such polymers, which are hydrophobic. These materials are available both as neutralized and un-neutralized. Suitable acid functional polymeric dispersants include, but are not limited to Tamol 165 A, 681 and 731 A. These suitable dispersants are also known as hydrophobic copolymer dispersants with Tamol 165 A and 731 A being hydrophobic polycarboxylate dispersants and Tamol 681 being hydrophobic acrylic dispersant.

[0033] The advantages derived from the present invention are illustrated in the Examples below.

[0034] Example 1. Exemplary Vinyl-Acrylic Copolymer Latex ResinMonomer Mixture Weight %diacetone acrylamide (DAAM) 0.87%vinyl acetate (VA) 87.44%butyl acrylate (BA) 11.40%acrylic acid (AA) 0.29%Total (grams) 1,754.3Weight % of non-ionic and 2.46%anionic surfactants and colloidalstabilizer based on total resinsolidsParticle size 334 nmSolid 52.4%pH 4.72Tg (Fox) 18.8°CMFFT (ISO 2115) 14°CMn 59000Mw 149000PDI 2.52Docket No. BJM-136. PCT

[0035] In this exemplary latex resin, vinyl monomer(s) makes up 87.44 wt.% or nominally 90% and the meth(acrylate) monomers make up 12.56%. DAAM is a crosslinking monomer and AA is an acid monomer typically used in emulsion polymerization in small amounts.

[0036] The latex resin from Example 1 and other suitable vinyl-acrylic latex resins are listed below in Table 1. The values of vinyl monomers are rounded up / down to integers ending in zero for convenience.Example 1 Example 2 Example 3 Example 4 Vinyl Acetate 90 90 70 70 Butyl Acrylate 10 10 20 30 Vinyl neodecanoate 0 0 10 0 (Veova 10)Acrylic Acid 1 0 0 0 | Diacetone Acrylamide 1 0 0 0 J Particle size (nm) 300 400 300 300 | Solids 50% 50% 50% 50% | pH 5 5 581 Tg (calculated Fox) 18.8°C 18.2°C 6.8°C 3.7°C i MFFT (ISO 2115) 14°C 11 °C 8°C 3°C | Mn 59000 46000 39500 63000 | Mw 149000 132000 101000 155000 PDI 2.52 2.87 2.55 2.46

[0037] Suitable vinyl monomers include vinyl esters, such as, for example, vinyl acetate (VA), vinyl neodecanoate (VeoVa 10), vinyl propionate, vinyl laurate, vinyl pivalate, vinyl nonanoate, vinyl decanoate, vinyl neodecanoate, vinyl butyrates, vinyl caproate, vinyl benzoates, vinyl isopropyl acetates and similar vinyl esters; nitrile monomers, such (meth)acrylonitrile and the like; vinyl aromatic hydrocarbons, such as, for example, styrene, methyl styrenes and similar lower alkyl styrenes, chlorostyrene, vinyl toluene, vinyl naphthalene and di vinyl benzene; vinyl aliphatic hydrocarbon monomers, such as, for example, vinyl chloride and vinylidene chloride as well as alpha olefins such as, for example, ethylene, propylene, isobutylene, as well as conjugated dienes such as 1,3-butadiene, methyl-Docket No. BJM- 136. PCT 2-butadiene, 1,3-piperylene, 2,3-dimethyl butadiene, isoprene, cyclohexene, cyclopentadiene, and dicyclopentadi ene; and vinyl alkyl ethers, such as, for example, methyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, and isobutyl vinyl ether.

[0038] Any meth(acrylate) monomers can be used or copolymerized with the preferred vinyl monomers. Since VA, a preferred vinyl monomer, is hydrophilic, preferred eth(acrylate) monomers should be hydrophobic, such as BA and 2-EHA. Other suitable meth(acrylate) monomers, as well as suitable styrene and other vinyl monomers, are disclosed in commonly owned U. S. patent No. 11,639,406, which is incorporated herein in its entirety. Some of these monomers are summarized below.

[0039] Any (meth)acrylic monomers can be used in the present invention. Suitable (meth)acrylic monomers include, but are not limited to methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, iso-octyl (meth)acrylate, lauryl (meth)acrylate, 2- ethylhexyl (meth)acrylate, stearyl (meth)acrylate, isobomyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-ethyoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, dimethylamino ethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, alkyl (meth)acrylic acids, such as methyl (meth)acrylate acids, (meth)acrylic acids, wet adhesion monomers, such as N-(2-methacryloyloxyethyl)ethylene urea, and multifunctional monomers such as divinyl benzene, diacrylates, for crosslinking functions etc., acrylic acids, ionic acrylate salts, alkacrylic acids, ionic alkacrylate salts, haloacrylic acids, ionic haloacrylate salts, acrylamides, alkacrylamides, monoalkyl acrylamides, monoalkyl alkacrylamides, alkyl acrylates, alkyl alkacrylates, acrylonitrile, alkacrylonitriles, dialkyl acrylamides, dialkyl alkacrylamides, hydroxyalkyl acrylates, hydroxyalkyl alkacrylates, only partially esterified acrylate esters of alkylene glycols, only partially esterified acrylate esters of non-polymeric polyhydroxy compounds like glycerol, only partially esterified acrylate esters of polymeric polyhydroxy compounds, itaconic acid, itaconic mono and di-esters, and combinations thereof. The preferred alkyl (meth)acrylate monomers are methyl methacrylate and butyl acrylate.

[0040] Preferred monomers containing aromatic groups are styrene and α-methylstyrene. Other suitable monomers containing aromatic groups include, but are not limited to, 2,4-diphenyl-4-methyl- 1 -pentene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, 2,3,4,5,6-pentafluorostyrene, (vinylbenzyl)trimethylammonium chloride, 2,6-dichlorostyrene, 2-fluorostyrene, 2-isopropenylaniline, 3(trifluoromethyl)styrene, 3-fluorostyrene, α-Docket No. BJM-136. PCT methylstyrene, 3-vinylbenzoic acid, 4-vinylbenzyl chloride, a-bromostyrene, 9- vinylanthracene, and combinations thereof.

[0041] Preferred monomers containing primary amide groups are (meth)acrylamides.Suitable monomers containing amide groups include, but are not limited to, N-vinylformamide, or any vinyl amide, N, N-dimethyl(meth)acrylamide, N-(l,l-dimethyl-3- oxobutyl)(meth)acrylamide, N-(hydroxymethyl)(meth)acrylamide, N-(3-methoxypropyl)(meth)acrylamide, N-(butoxymethyl)(meth)acrylamide, N-(isobutoxymethyl)acryl(meth)acrylamide, N- [tris(hydroxymethyl)methyl]acryl(meth)acrylamide, 7-[4-(trifluoromethyl)coumarinj(meth)acrylamide, 3 -(3 -fluoropheny l)-2-propenamide, 3 -(4-methylphenyl)(meth)acrylamide, N-(tert-butyl)(meth)acrylamide, and combinations thereof. These monomers can be polymerized with acrylic monomers, listed above. General formula for vinyl(form)amides are:CH2” — CR1——NH — COR2and (meth)acrylamides:CCH2== CR1— CO — NR3— R2where R1 and R2 can be — H, — CH3, — CH2CH3, and other substituted organic functional groups and R3 can by — H, an alkyl or an aryl.

[0042] In one embodiment, styrene monomers, such as styrene, methylstyrene, chlorostyrene, methoxystyrene and the like, are preferably co-polymerized with (meth)acrylamide monomers.Docket No. BJM-136. PCT

[0043] In one embodiment, the aqueous latex polymer may also comprise vinyl monomers. Monomers of this type suitable for use in accordance with the present invention include any compounds having vinyl functionality, i.e., — CH=CH2 group. Preferably, the vinyl monomers are selected from the group consisting of vinyl esters, vinyl aromatic hydrocarbons, vinyl aliphatic hydrocarbons, vinyl alkyl ethers and mixtures thereof.

[0044] Suitable vinyl monomers include vinyl esters, such as, for example, vinyl acetate, vinyl propionate, vinyl laurate, vinyl pivalate, vinyl nonanoate, vinyl decanoate, vinyl neodecanoate, vinyl butyrates, vinyl caproate, vinyl benzoates, vinyl isopropyl acetates and similar vinyl esters; nitrile monomers, such (meth)acrylonitrile and the like; vinyl aromatic hydrocarbons, such as, for example, styrene, methyl styrenes and similar lower alkyl styrenes, chlorostyrene, vinyl toluene, vinyl naphthalene and divinyl benzene; vinyl aliphatic hydrocarbon monomers, such as, for example, vinyl chloride and vinylidene chloride as well as alpha olefins such as, for example, ethylene, propylene, isobutylene, as well as conjugated dienes such as 1,3 -butadiene, methyI-2-butadiene, 1,3-piperylene, 2,3-dimethyl butadiene, isoprene, cyclohexene, cyclopentadiene, and dicyclopentadiene; and vinyl alkyl ethers, such as, for example, methyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, and isobutyl vinyl ether.

[0045] Preferably vinyl monomers should make up from about 70 wt.% to 90 wt.% of the total monomer weight in the copolymers.

[0046] The resin in Example 1 was incorporated into a 1-base paint (Paint Example 1), which also includes the tristyryl phenol ethoxylate phosphate surfactant and anionic dispersant discussed above.Paint Example 1 | f Weight % Water | 23.268 Ammonium hydroxide 26 BE (29.4%) pH control buffer | 0.286 Biocide 1 0.095 Biocide 2! 0.191 Dry-film preservative 0.048 Fungicide | 0.143 Styrene-maleic acid copolymer dispersant j 1.254 Tristyryl phenol ethoxylate phosphate surfactant j 0.611Docket No. BJM-136. PCT foam breaking agent 0.191 TiO2opacifying pigment 17.623 Mineral filler extender pigment 1 1.905 Mineral filler extender pigment 2 4.287 Coalescent agent 1.420 Surfactant § 0.667 Hydrophobically modified ethylene oxide urethane (HEUR) 1.143 rheology modifierExample 1, VA / BA Latex 40.485 Adipic acid dihydrazide (ADH) 0.381 Synthetic pigment 3.810 VOC-free associative thickener (HASE) 0.667 Paraffin wax emulsion 0.953 Defoaming agent 0.572Total: 100%f weight percentages for all paint components include water, and can be referred to as wet wt.%§ nonionic wetting agent or surfactant with a HLB of about 13, which is present in all paint formulations that are tested herein. This wetting agent is utilized to help with stability of the final paint formulations.

[0047] Vinyl-acrylic paints, similar to Paint Example 1, were made with varying amounts of styrene-maleic acid copolymer dispersant and tristyryl phenol ethoxylate phosphate surfactant, as well as other dispersants. These paints were placed in a 120 °F incubator for 1 - week, 2-week and 1 -month periods as an accelerated simulation of long-term storage. The ATS for Paint Example 1 at 2 weeks is 2.3% and the ATS at 4 weeks is 3.2%. Negative ATS values indicate an improvement or an increase in tint strength. The test results are shown below in Table 2.TABLE 2Docket No. BJM-136. PCT TristyrylStyrenephenolConvent, maleic acid A TS A TS A TS Paint Ex. Resin ethoxylatedispersant copolymerphosphatedispersantsurfactant 1 -week 2-week 1-mth 1.1Control 1 Ex.l none none 15.74 23.75 wt.%cPaint 1 Ex.l 2.0 wt.% 2.0 wt.% 2.30 3.20 2 Ex.l 0.4 wt.% 0.7 wt.% 4.76 9.63 Ex.l 1.03 1.0 wt.% 1.05 6.21 wt.%bEx.l 1.14 1.4 wt.% 10.65 wt.%c5 Ex.l 1.4 wt.% 1.4 wt.% TQ9“ 4.91 Ex.l 1.16 2.0 wt. % 3.76 wt.%cEx.l 1.27 2.7 wt.% 5.78 5.84 wt.%a— —Ex.l82.7 wt.% 6.64 5.62 wt.%cEx.l 3.37 wt.% 3.37 wt.% -1.37 1.68 - ~ - - __ Ex.1 7.0 wt.% 7.0 wt.% -0.731.1Control 4 Ex.4 none none 7.22 16.06 wt.%c1.111 Ex.4 2.0 wt. % 10.05 wt.%c1.1Control 2 Ex.2 none none - 16.26 wt.%c1.112 Ex.2 2.0 wt. % 7,11 wt.%01.1Control 3 Ex. 3 none none 11.5 16.09 wt.%cDocket No. BJM-136. PCTaTamol 681 dispersant (35% solid, ammonia salt).bTamol 165 A dispersant (21% solid, ammonia salt).cTamol 731 A dispersant (25% solid, sodium salt). Tamol dispersants are available from Dow Chemical.Control paint examples 1 -4 include the nonionic wetting agent or surfactant denoted as § in Paint Example 1 at similar amounts.The weight percentages (wt.%) shown in Table 2 are calculated by taking the weight of the active ingredient(s) in the surfactants or dispersants and dividing them by the weight of the combined opacifying pigment, i.e., TiO2and extender pigments. In one example, wt.% (Table 2) = {weight of the surfactant or dispersant x % active ingredients therein} {combined weight of the TiO2and extender pigments} x 100%. These weight percentages can be thought of as ratios, but are referred to in the art of architectural coatings as weight percentages.

[0048] The present inventors have determined that a ATS of less than about 10 after 4 weeks, more preferably less than about 7 in 4 weeks, represents an improvement in tint strength, in other words an acceptable tint strength drift. Less than “about 10” includes ATS that are higher than 10 in inventive Paint Examples 4 and 11, and less than “about 7” includes ATS that are higher than 7 in inventive Example 12.

[0049] The ATS at 1 -month is a preferred elapsed time period.

[0050] Control paint examples 2-4 show similar ATS values of about 16 indicating similar loss of tint strength among vinyl acrylic paints. Control paint sample 1 has higher A TS value and is used as a comparative for inventive Paint Examples 1-10.

[0051] Inventive Paint Examples 10 shows that at a higher 7% weight percentage of tristyryl phenol ethoxylate phosphate surfactant and styrene-maleic acid copolymer dispersant, the ATS value remains a low 2.98 indicating that the weight percentages of these surfactant and dispersant could be significantly higher.

[0052] Based on the experiments shown in Table 2, the preferred range of tristyryl phenol ethoxylate phosphate surfactant is from about 0.5 wt.% to about 8.0 wt.%, more preferably from about 0.6 wt.% to about 7.5 wt.%, more preferably from 0.7 wt.% to about 7wt.%.

[0053] Based on the experiments shown in Table 2, the preferred range of styrene-maleic acid copolymer dispersant is from about 0.3 wt.% to about 8.0 wt.%, more preferably from about 0.4 wt.% to about 7.0 wt.%.Docket No. BJM-136. PCT

[0054] Based on the experiments shown in Table 2, the preferred range of hydrophobic copolymer dispersant, including hydrophobic acrylic dispersant and hydrophobic polycarboxylate dispersants, is from about 0.5 v.% to about 2 wt.%, preferably from about 0.75 wt.% to about 1.75 wt.%, more preferably from about 1.0 wt.% to about 1.5 wt.%.

[0055] While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. 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.

Claims

Docket No. BJM-136. PCT CLAIMSWe claim:

1. An aqueous architectural composition comprisingan opacifying pigment,a copolymer polymerized from at least one vinyl monomer, preferably a vinyl acetate or vinyl neodecanoate, and at least one meth(acrylate) monomer, preferably a hydrophobic meth(acrylate) monomer, wherein the at least one vinyl monomer makes up from about 70 wt.% to about 90 wt.% of all monomer weight,a tristyryl phenol ethoxylate phosphate surfactant from about 0.5 wt.% to about 8.0 wt.%, preferably from about 0.6 wt.% to about 7.5 wt.%, more preferably from 0.7 wt.% to about 7wt.% of the aqueous architectural composition, anda styrene-maleic acid copolymer dispersant from about 0.3 wt.% to about 8.0 wt.%, more preferably from about 0.4 wt.% to about 7.0 wt.% of the aqueous architectural composition,wherein wt.% of the surfactant or the dispersant is a weight of active ingredients in the surfactant or the dispersant divided by a combined weight of the opacifying pigment and extender pigment.

2. The aqueous architectural composition of claim 1, wherein the tristyryl phenol ethoxylate phosphate surfactant comprises a neutralized tristyryl phenol ethoxylate (14EO) phosphate with mono-, di-, tri- and tetra species.

3. The aqueous architectural composition of claim 1, wherein the styrene-maleic acid copolymer dispersant comprises a neutralized poly(isobutylene-alt-maleic anhydride) dispersant.

4. An aqueous architectural composition comprisingan opacifying pigment,a copolymer polymerized from at least one vinyl monomer, preferably a vinyl acetate or vinyl neodecanoate, and at least one meth( acrylate) monomer, preferably a hydrophobic meth(acrylate) monomer, wherein the at least one vinyl monomer makes up from about 70 wt.% to about 90 wt.% of all monomer weight,Docket No. BJM-136. PCT a tristyryl phenol ethoxylate phosphate surfactant from about 0.5 wt.% to about 8.0 wt.%, more preferably from about 0.6 wt.% to about 7.5 wt.%, more preferably from 0.7 wt.% to about 7wt.% of the aqueous architectural composition, anda hydrophobic copolymer dispersant, including hydrophobic acrylic dispersant and hydrophobic polycarboxylate dispersants, from about 0.5 v.% to about 2.0 wt.%, preferably from about 0.75 wt.% to about 1.75 wt.%, more preferably from about 1.0 wt.% to about 1.5 wt.%wherein wt.% of the surfactant or the dispersant is a weight of acti ve ingredients in the surfactant or the dispersant divided by a combined weight of the opacifying pigment and extender pigment.

5. The aqueous architectural composition of claim 4, wherein the hydrophobic copolymer dispersant, including hydrophobic acrylic dispersant and hydrophobic polycarboxylate dispersants, comprises a sodium or ammonia salt of the dispersant.

6. The aqueous architectural composition of claim 4, wherein the tristyryl phenol ethoxylate phosphate surfactant comprises a neutralized tristyryl phenol ethoxylate (14EO) phosphate with mono-, di-, tri- and tetra species.

7. The aqueous architectural composition of any of the above claims, wherein the opacifying pigment is TiO2.

Images