WO2013174934A1

WO2013174934A1 - Aqueous latex-based coating components

Info

Publication number: WO2013174934A1
Application number: PCT/EP2013/060642
Authority: WO
Inventors: Joerg Schulte; Stefan Nogai; An NA; Jinje DU; Yifang SHI
Original assignee: Celanese Emulsions Gmbh
Priority date: 2012-05-23
Filing date: 2013-05-23
Publication date: 2013-11-28
Also published as: CN104302717A

Abstract

Disclosed are aqueous latex-based coating components and surfactant stabilized coating components which comprise a non-ionic surfactant, a neutralized phosphate surfactant, and a copolymer of at least a vinyl ester of a C_1-13alkanoic acid and ethylene. The weight ratio of non-ionic surfactant to neutralized phosphate surfactant is greater than 1:1. The components may be free of protective colloids. The coating components may be incorporated into latex paint compositions. The latex paint compositions exhibit high pigment volume concentration and high wet scrub resistance.

Description

AQUEOUS LATEX-BASED COATING COMPONENTS

Priority Claim

[0001] This application claims priority to US Provisional Appl. No. 60/650,645, filed May 23, 2012, the entirety of which is hereby incorporated by reference.

Field

[0002] The present invention relates to an aqueous latex-based coating component comprising copolymers of vinyl esters and ethylene, a neutralized non- ionic surfactant and a neutralized phosphate surfactant. The present invention also relates to methods for preparing this component. The present invention further relates to paint compositions comprising the aqueous latex-based coating component.

Background

[0003] Latex-based paints have captured a significant portion of the indoor and outdoor paint market as a result of the many advantages that such paints have over solvent-based products. The main advantage of latex-based paints include easy clean up, low odor and fast dry.

[0004] Two main types of emulsion polymers are employed in formulating latex paints, namely (1 ) acrylic emulsion copolymers, comprising of alkyl esters of acrylic and methacrylic acid, or combinations of such esters with vinyl aromatic co- monomers like styrene, along with minor amounts of acrylic and methacrylic acid, and (2) vinyl acetate copolymers, comprising vinyl acetate in combination with ethylene, (VAE), vinyl chloride and/or minor amounts of softer acrylic monomers. The acrylic emulsion polymers are mainly used in premium quality paints for excellent water resistance, desired levelling, film hardness and scrub resistance. The VAE copolymers exhibit toughness but have poor scrub resistance. VAE copolymers tend to be much less expensive than the acrylic copolymers

[0005] Although there are advantages to using VAE-based latex paints, it is well documented that several deficiencies exist for VAE emulsions in paint products versus solvent-based paints and acrylic-based latex paints. One such deficiency relates to scrub resistance. The term "scrub resistance" is used in the paint industry to describe the ability of a paint coating to resist erosion when scrubbed. As higher pigment volume concentration (PVC), the ratio of pigment volume to total volume of the paint, is increased to maximize coating coverage, scrub resistance decreases.

[0006] Much effort has been devoted in the past to improving the scrub resistance capabilities of latex-based paints. This effort has involved attempts to optimize various paint formulation parameters, such as using silane binders, using coalescing solvents, and using specific surfactants in combination with protective colloids.

[0007] In particular, U.S. Patent No. 4,277,385 to Carroll et al. discloses the inclusion of plastic pigment particles to provide a high PVC acrylic binder formulation while maintaining good physical properties. The formulation may also comprise coalescing solvents.

[0008] U.S. Patent No. 6,673,854 to Pierre et al. discloses an aqueous vinyl acetate-ethylene polymer dispersion comprising vinyl acetate, ethylene and an optional third monomer, an alcohol ether phosphate surfactant with 4 to 70 ethylene oxide units, at least one protective colloid, and water. Pierre et al. disclose the use of neutralized phosphate surfactants but teach that a protective colloid is required to stabilize the polymer. The protective colloid may be hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), among others.

[0009] Notwithstanding the above-described prior art techniques for improving scrub resistance of VAE based latex paints, there continues to be a need to identify new coating formulations, especially in the form of paints, which employ VAE and which also provide high PVC and high scrub resistance.

[0010] Surprisingly and unexpectedly, it has been found the scrub resistance of a VAE based latex paint may be improved, while preserving high PVC, by using a combination of non-ionic and neutralized phosphate surfactants. It has further surprisingly and unexpectedly been found that this combination of surfactants may reduce or eliminate the need for the dispersions to be stabilized by protective colloids.

Summary [0011] In a first embodiment, the present invention is directed to an aqueous latex-based coating component, comprising: (a) a copolymer of at least a vinyl ester of a Ci-i3 alkanoic acid and ethylene; (b) a non-ionic surfactant; and (c) a neutralized phosphate surfactant, wherein the weight ratio of non-ionic surfactant to neutralized phosphate surfactant is greater than 1 :1 .

[0012] In a second embodiment, the present invention is directed to a paint composition, comprising: (i) the aqueous latex-based coating component of described in the first embodiment; (ii) a pigment component selected from inorganic pigments, inorganic fillers and mixtures thereof present in an amount such that the paint composition has a pigment volume concentration (PVC) of from about 25 vol% to 90 vol%; and (ii) at least one auxiliary component selected from the group consisting of wetting agents, dispersants, emulsifiers, fillers, thickeners, antifoams, dyes and preservatives.

[0013] In a third embodiment, the present invention is directed to a surfactant- stabilized coating component, said composition comprising: (a) a copolymer comprising at least a vinyl ester of a C1-13 alkanoic acid and ethylene; (b) a non- ionic surfactant; and (c) a neutralized phosphate surfactant, wherein the composition is free of protective colloids.

[0014] In a fourth embodiment, the present invention is directed to a method of making an aqueous latex-based coating component, comprising copolymerizing at least a vinyl ester of a C1-13 alkanoic acid and ethylene in the presence of a non- ionic surfactant and a neutralized phosphate surfactant in the absence of protective colloids.

[0015] In a fifth embodiment, the present invention is directed to a method of making an aqueous latex-based coating component, comprising copolymerizing at least a vinyl ester of a C1-13 alkanoic acid and ethylene in the presence of a non- ionic surfactant and a neutralized phosphate surfactant at a non-ionic surfactant to neutralized phosphate surfactant weight ratio greater than 1 :1 . Detailed Description

[0016] In general, this invention relates to an aqueous latex-based coating component and preparation methods thereof, wherein the component is stabilized by a combination of non-ionic and neutralized phosphate surfactants. In particular, the component comprises the surfactants and a copolymer of at least a vinyl ester of a C-1-13 alkanoic acid and ethylene. The weight ratio of non-ionic surfactant to neutralized phosphate surfactant is greater than 1 :1 . In some embodiments, the weight ratio of non-ionic surfactant to neutralized phosphate surfactant may be 3:2. Advantageously, the present invention provides an industrially feasible aqueous latex-based coating component which may be incorporated into paint compositions or coating compositions.

[0017] This invention also relates to a surfactant-stabilized coating component. The component is stabilized by a neutralized phosphate surfactant and a non-ionic surfactant. The component comprises a copolymer of at least a vinyl ester of a C1-13 alkanoic acid and ethylene. The component is free of protective colloids. Advantageously, the present invention provides an industrially feasible aqueous latex-based coating component that avoids the use of protective colloids and which may be incorporated into paint compositions or coating compositions.

[0018] The copolymer used in both the aqueous latex-based coating component and in the surfactant-stabilized coating component may be comprised of at least a vinyl ester of a C1-13 aklanoic acid and ethylene. In some embodiments, the vinyl ester is vinyl acetate. The copolymer and preparation thereof is detailed below. The copolymer may be present from 1 to 20 wt.%, e.g., from 3 to 12 wt.%.

Surfactants

[0019] The coating components comprise a non-ionic surfactant and a neutralized, e.g., fully neutralized, phosphate surfactant. In some embodiments, the weight ratio of non-ionic surfactant to neutralized phosphate surfactant is greater than 1 :1 . In terms of ranges, the weight ratio of non-ionic surfactant to neutralized phosphate surfactant may be from 1 :1 to 3:1 . In still other embodiments, the weight ratio of non-ionic surfactant to neutralized phosphate surfactant is about 3:2.

[0020] Suitable nonionic surfactants which can be used as emulsifiers in the emulsion stabilizing system of the copolymer and coating compositions herein include polyoxyethylene condensates. A wide variety of nonionic surfactants of this type are disclosed in the hereinbefore-referenced U.S. Patent No. 5,849,389. Even though polyoxyethylene condensates can be used as nonionic emulsifiers in the preparation of the copolymer emulsions and coating compositions herein, the emulsions and compositions herein may be substantially free of alkyl phenol ethoxylates (APE) such as octyl phenol ethoxylates. These represent a class of compounds typically used as surfactants that degrade to alkyl phenols. Such compounds are of environmental concern due to their estrogen mimicking characteristics.

[0021 ] In some embodiments, the non-ionic surfactant comprises a branched or linear Ci_-5o carbyl component with linking functionality and 4 to 100 ethylene oxide units. The linking functionality may be an ether or ester. In still other embodiments, the non-ionic surfactant may comprise ethoxylated linear fatty alcohols. One example of the non-ionic surfactant is sold as Disponil® A3065, which is a mixture of ethoxylated linear fatty acids with 30 moles of ethylene oxide.

[0022] The phosphate surfactant is neutralized, e.g., fully neutralized. In some embodiments, the phosphate surfactant may be neutralized with sodium hydroxide. The phosphate surfactant may comprise a CM_S ester of phosphoric acid, e.g., a C12 ester of phosphoric acid. In further embodiments, the phosphate surfactant may comprise 4 to 20 ethylene oxide units, e.g., from 6 to 10 ethylene oxide units. One example of the phosphate surfactant is sold as Rhodafac® RS-610 A25, a polyoxyethylene tridecyl ether phosphate, ammonium salt, that may be fully neutralized.

[0023] The components of the present invention may also comprise an anionic surfactant in addition to the neutralized phosphate surfactant and non-ionic surfactant. Suitable anionic surfactants which can be used as emulsifiers in the emulsion stabilizing system of the emulsion copolymer and coating compositions herein include alkyl aryl sulfonates, alkali metal alkyl sulfates, sulfonated alkyl esters and fatty acid soaps. A wide variety of anionic surfactants of this type are also disclosed in the hereinbefore-referenced U.S. Patent No. 5,849,389.

Protective Colloids

[0024] Conventionally, various protective colloids such as polyvinyl alcohol and other conventional protective colloid-forming materials have also been used to stabilize emulsion polymer latex compositions of the types hereinbefore described, instead of or in addition to the surfactant emulsifiers. In some preferred embodiments, the emulsions and compositions herein can be substantially free of such protective colloids as stabilizing agents. Protective colloids may include hydroxyethyl cellulose and polyvinyl alcohol. Such emulsions are considered to be "substantially free" of protective colloids if protective colloids comprise no more than 0.5 wt% of the emulsions and compositions, based on the total amount of copolymers in the emulsions or compositions being stabilized. The latex emulsions and compositions herein which utilize emulsifier, i.e., surfactant, stabilizing agents and are substantially free of protective colloids are characterized herein as being "substantially all-surfactant-based" emulsions and compositions.

[0025] In still further embodiments, the coating component may be free of protective colloids. Without being bound by theory, protective colloids may be eliminated from the coating component because the combination of non-ionic surfactant and neutralized phosphate surfactant serves to stabilize the coating component. Ethylene-Vinyl Acetate (VAE) Copolymer

[0026] One type of emulsion copolymer used in the blend of copolymers which forms the compositions herein comprises a copolymer of vinyl acetate and ethylene. Ethylene-vinyl acetate copolymers which can be abbreviated as "EVA" or "VAE" copolymers are well-known in the art.

[0027] The VAE copolymer is an aqueous emulsion polymerization product of ethylene, vinyl acetate, and optionally other unsaturated co-monomers which form an emulsion copolymer. The amount of ethylene monomer used to prepare the VAE copolymer may be from about 5 wt% to about 20 wt%, e.g., from about 10 wt% to about 15 wt%, based on the total weight of co-monomers used to prepare the VAE copolymer. The amount of vinyl acetate used to prepare the VAE copolymer may be from about 70 wt% to about 95 wt%, e.g., from about 75 wt% to about 90 wt%, based on the total weight of co-monomers used to prepare the VAE copolymer.

[0028] The VAE copolymer used in the blend of the compositions herein may also contain from 0 wt% to about 10 wt%, e.g., from about 0.1 wt% to about 5 wt%, of one or more optional unsaturated co-monomers, based on the total weight of co- monomers used to prepare the VAE copolymer. Such optional co-monomers can include, for example, C1-C12 esters of (meth)acrylic acid such as are also used to form the acrylic copolymer component of the copolymer blend. Other types of optional co-monomers for the use in forming the VAE emulsion copolymer are described in greater detail hereinafter. Preferably, however, the VAE copolymer used in the blends which form the compositions herein should be substantially free of co-monomers which contain unesterified carboxyl moieties.

Optional Auxiliary Co-Monomers

[0029] The VAE emulsion copolymers used in the blends which form the compositions herein can contain a variety of optional co-monomers. Such optional co-monomers can be those which promote better film-forming or coating-forming performance by the compositions herein or can provide realization of films and coatings of desirable properties. Such desirable film/coating properties can include, for example, enhanced adhesion to surfaces or substrates, improved wet adhesion, better resistance to removal by scrubbing or other types of weathering or abrasion, and improved resistance to film or coating cracking.

[0030] The optional co-monomers useful for incorporation into the emulsion copolymers of the compositions herein are those which contain at least one polymerizable double bond along with one or more additional functional moieties. Such optional or auxiliary co-monomers can thus include unsaturated silane co- monomers, glycidyl co-monomers, ureido co-monomers and combinations of these auxiliary optional co-monomers.

[0031] Unsaturated silanes useful as optional co-monomers can generally correspond to a substituted silane of the structural Formula I:

Formula I in which R denotes an organic radical olefinically unsaturated in the ω-position and R¹| R² and R³ which may be identical or different, denote halogen, preferably chlorine, or the group -OZ, Z denoting hydrogen or primary or secondary alkyl or acyl radicals optionally substituted by alkoxy groups. Suitable unsaturated silane compounds of the Formula I are preferably those in which the radical R in the formula represents an ω-unsaturated alkenyl of 2 to 10 carbon atoms, particularly of 2 to 4 carbon atoms, or an ω-unsaturated carboxylic acid ester formed from unsaturated carboxylic acids of up to 4 carbon atoms and alcohols carrying the Si group of up to 6 carbon atoms. Suitable radicals R¹ , R², R³ are preferably the group -OZ, Z representing primary and/or secondary alkyl radicals of up to 10 carbon atoms, preferably up to 4 carbon atoms, or alkyl radicals substituted by alkoxy groups, preferably of up to 3 carbon atoms, or acyl radicals of up to 6 carbon atoms, preferably of up to 3 carbon atoms, or hydrogen. Most preferred unsaturated silane co-monomers are vinyl trialkoxy silanes.

[0032] Examples of preferred silane compounds of the Formula I include v- methacryloxypropyltris(2-methoxyethoxy)silane, vinylmethoxysilane, vinyltriethoxysilane, vinyldiethoxysilanol, vinylethoxysilanediol, allyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltriacetoxysilane, trimethylglycolvinylsilane, γ- methacryloxypropyltrimethylglycolsilane, γ-acryloxypropyltriethoxysilane and γ- methacryloxypropyltrimethoxysilane.

[0033] Glycidyl compounds can also be used as optional auxiliary co-monomers in the VAE emulsion copolymer. Glycidyl compounds are epoxy-containing materials and can facilitate cross-linking of the emulsion copolymers in the copolymer blend. Examples of suitable glycidyl optional co-monomers include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, vinyl glycidyl ether, vinyltoluenes and styrenes substituted with a glycidyl radical in the aromatic moiety, and vinylbenzoates substituted with a glycidyl radical in the aromatic moiety

[0034] Another type of optional co-monomer for use in the VAE emulsion copolymer components comprises cyclic ureido co-monomers. Cyclic ureido co- monomers are known to impart improved wet adhesion properties to films and coatings formed from copolymers containing these co-monomers. Cyclic ureido compounds and their use as wet adhesion promoting co-monomers are disclosed in U.S. Patent Nos. 4,104,220; 4,1 1 1 ,877; 4,219,454; 4,319,032; 4,599,417 and 5,208,285. The disclosures of all of these U.S. patents are incorporated herein by reference in their entirety. Coating Component Preparation

[0035] The VAE copolymers comprising the essential and optional co- monomers hereinbefore described can be prepared using conventional emulsion polymerization procedures which result in the preparation of copolymer emulsions. These emulsions can then be incorporated into the coating compositions herein in aqueous latex form. Such procedures are described, for example, in U.S. Patent No. 5,849,389, the disclosure of which is incorporated herein by reference in its entirety.

[0036] Generally, the aqueous latex-based coating component is prepared by copolymerizing at least a vinyl ester of a C1-13 alkanoic acid and ethylene in the presence of a non-ionic surfactant and a neutralized phosphate surfactant, in the absence of protective colloids. In another method, the aqueous latex-based coating composition is prepared by copolymerizing at least a vinyl ester of a C1-13 alkanoic acid and ethylene in the presence of a non-ionic surfactant and a neutralized phosphate surfactant. The weight ratio of non-ionic surfactant to neutralized phosphate surfactant is greater than 1 :1 , e.g., from 1 :1 to 3:1 or about 3:2. The vinyl ester in both preparation methods may be vinyl acetate.

[0037] The amount of ethylene monomer used to prepare the VAE copolymer may be from about 5 wt% to about 20 wt%, e.g., from about 10 wt% to about 15 wt%, based on the total weight of co-monomers used to prepare the VAE copolymer. The amount of vinyl acetate used to prepare the VAE copolymer may be from about 70 wt% to about 95 wt%, e.g., from about 75 wt% to about 90 wt%, based on the total weight of co-monomers used to prepare the VAE copolymer.

[0038] The VAE copolymer used in the blend of the compositions herein may also contain from 0 wt% to about 10 wt%, e.g., from about 0.1 wt% to about 5 wt%, of one or more optional unsaturated co-monomers, based on the total weight of co- monomers used to prepare the VAE copolymer.

[0039] In a typical polymerization procedure, the vinyl ester, ethylene, and other optional co-monomers can be polymerized in an aqueous medium in a suitable polymerization vessel under pressures not exceeding 100 atmospheres in the presence of a catalyst component and at least one emulsifying agent. The aqueous reaction mixture in the polymerization vessel can be maintained by a suitable buffering agent at a pH of about 2 to 9. [0040] The manner of combining the several polymerization ingredients, i.e., emulsifiers, co-monomers, catalyst system components, etc., can vary widely. Generally an aqueous medium containing at least some of the emulsifier(s) can be initially formed in the polymerization vessel with the various other polymerization ingredients being added to the vessel thereafter.

[0041] Co-monomers can be added to the polymerization vessel continuously, incrementally or as a single charge addition of the entire amounts of co-monomers to be used. Co-monomers can be employed as pure monomers or can be used in the form of a pre-mixed emulsion. Ethylene as a co-monomer can be pumped into the polymerization vessel and maintained under appropriate pressure therein.

[0042] The catalyst system components can also be added to the polymerization vessel continuously, incrementally in stages, or as a single charge addition. Suitable polymerization catalysts include the water-soluble free-radical-formers (initiators) generally used in emulsion polymerization, such as hydrogen peroxide, sodium persulfate, potassium persulfate and ammonium persulfate, as well as tert- butyl hydroperoxide, in amounts of between 0.01 % and 3% by weight, preferably 0.01 % and 1 % by weight, based on the total amount of the emulsion. These materials can be used together with reducing agents such as sodium formaldehyde-sulfoxylate, ferrous salts, sodium dithionite, sodium hydrogen sulfite, sodium sulfite, sodium thiosulfate, as redox catalysts in amounts of 0.01 % to 3% by weight, preferably 0.01 % to 1 % by weight, based on the total amount of the emulsion. The free-radical-formers can be added to the aqueous emulsifier solution initially present in the polymerization vessel or can be added during the polymerization in staged doses. When redox systems are to be formed in the polymerization vessels, the initiator should be added separately, e.g., in separate solutions, from the reducing agent(s).

[0043] As noted, the entire amount of the aqueous medium with the polymerization additives can be present in the polymerization vessel before introduction of the co-monomers. Or alternatively, the aqueous medium, or a portion of it, can be added continuously or incrementally during the course of the polymerization.

[0044] In a typical polymerization procedure, the polymerization reactor can be filled with an aqueous emulsifier solution. Then at least a part of the co-monomers to be polymerized are added. After this initial reaction mixture is homogenized via agitation, polymerization can be started by adding at least a part of the catalyst system in order to prepare in situ seed material. Thereafter incremental or continuous addition of the remaining co-monomers and catalyst system components can be carried out to complete the preparation of the emulsion polymer. Alternatively, instead of preparation of in situ seed material, an aqueous medium containing a seed dispersion may be separately prepared and added to the polymerization vessel, again followed by addition of the remaining co-monomers and catalyst material.

[0045] The emulsion polymerization used to prepare the copolymers in aqueous latex form is carried out in the presence of a stabilization system which comprises neutralized phosphate surfactants and nonionic surfactants as described herein. Coating/Paint Composition Formulation

[0046] The coating component is prepared from the blend of emulsion copolymers which form an aqueous, i.e., water-based, latex as disclosed herein. The term "latex" is used herein in its conventional sense, meaning, i.e., a dispersion of particulate matter in an aqueous phase which contains an emulsifier or surfactant suitable for preparing and stabilizing the latex. The latex coating compositions herein comprise a certain copolymer blend dispersed in an aqueous phase with an appropriate emulsifier system.

[0047] The essential components of the coating compositions herein are most commonly combined with other components which are conventionally used to form paint compositions. Paints can be formulated using techniques known to those skilled in the art of manufacturing paint. Generally, water, defoamer, pigment, filler (also known as extender pigment) and surfactant stabilizer (in addition to emulsifiers used during emulsion polymerization of the copolymer blend) are combined to form a grind, where the pigments and fillers are ground to a desired particle size as indicated by a Hegman reading of 2 to 6.

[0048] The "Hegman" reading is the most common way a grind dispersion (as opposed to a polymer dispersion) is characterized. Hegman numbers relate to the fineness of the grind dispersion measured in micrometers. A higher Hegman number means finer grind. A Hegman number of about 2 to about 3 is almost exclusive to a flat paint. Satin and Eggshell paints can have Hegman numbers in the range of about 3 to about 6 depending upon formulation, preferably in the range of 3 to less than 5. A Hegman number of about 6 represents a lower semi-gloss range. Additional water, the latex copolymer blend, rheology modifiers, biocides and the like are then added to the grind, and the entire batch is blended and adjusted to desired Hegman readings and viscosity, thereby forming the paint composition.

[0049] The coating component of the present invention may be incorporated into a paint composition comprising the coating component, a pigment component, and at least one auxiliary component. The pigment component may be selected from inorganic pigments, inorganic fillers and mixtures thereof. The pigment component is added so that the paint composition has a pigment volume concentration from about 25 vol% to 90 vol%. The at least one auxiliary component may be selected from the group consisting of wetting agents, dispersants, emulsifiers, fillers, thickeners, antifoams, dyes and preservatives.

[0050] Preferred fillers useful in the paint compositions herein can be, for example, calcium carbonate, magnesite, dolomite, kaolin, mica, talc, silica, calcium sulfate, feldspar, barium sulfate and opaque polymer. Examples of white pigments useful in the paint compositions herein can be zinc oxide, zinc sulfide, basic lead carbonate, antimony trioxide, lithopone (zinc sulfide+barium sulfate) and, preferably, titanium dioxide. Examples of inorganic colored pigments which may preferably be used in the paint compositions herein include iron oxides, carbon black, graphite, luminescent pigments, zinc yellow, zinc green, Paris blue, ultramarine, manganese black, antimony black, manganese violet or Schweinfurt green. Suitable organic colored pigments preferably are, for example, sepia, gamboge, Cassel brown, toluidine red, para red, Hansa yellow, indigo, azo dyes, anthraquinone and indigo dyes as well as dioxazine, quinacridone, phthalocyanin, isoindolinone and metal complex pigments of the azomethine series.

[0051] The fillers may be used as individual components. Mixtures of fillers such as, for example, calcium carbonate/kaolin and calcium carbonate/kaolin/talc have also been found to be particularly useful in practice. To increase the hiding power of the coating and to save on titanium dioxide, finely divided fillers such as, for example, finely divided calcium carbonate and mixtures of various calcium carbonates with different particle size distribution are frequently used. Calcined clays are commonly used to increase film dry opacity as they help incorporate air voids into the dry film. Air voids create a big difference in refractive index in the film and scatter light, yielding more opacity in the film once cured. To adjust the hiding power, the shade and the depth of color of the coatings formed, the fillers are mixed with appropriate amounts of white pigment and inorganic and/or organic colored pigments.

[0052] To disperse the fillers and pigments in water, 0.1 to 0.6% by weight, based on the total weight of the aqueous preparation, of auxiliaries based on anionic or non-ionic wetting agents, such as preferably, for example, sodium pyrophosphate, sodium polyphosphate, naphthalenesulfonate, sodium polyacrylate, sodium polymaleinates and polyphosphonates such as sodium 1 -hydroxyethane- 1 ,1 -diphosphonate and sodium nitrilotris(methylenephosphonate), may be added.

[0053] The paint compositions herein will preferably have a pigment volume concentration (PVC) ranging from about 25 vol% to about 90 vol%, e.g., from about 50 vol% to about 90 vol% or about 75 vol% to about 90vol%. PVC represents the volume of pigment plus fillers in the paint composition divided by the volume of pigment, fillers and film-forming copolymers times 100%. PVC is described in greater detail in U.S. Patent Publication No. 2010/0056696 which is incorporated herein by reference.

[0054] Thickeners may also be added to the paint formulations herein. Thickeners which may be used include, inter alia, preferably cellulose derivates such as methylcellulose (MC), hydroxyethylcellulose (HEC) and carboxymethyl- cellulose. Other thickeners which may be used include casein, gum arabic, gum tragacanth, starch, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate and water-soluble copolymers based on acrylic and methacrylic acid, such as acrylic acid/acrylamide and methacrylic acid/acrylic ester copolymers. Hydrophobically-modified alkali soluble (acrylic) emulsions (HASE), hydrophobically-modified ethoxylate (poly)urethanes (HEUR), and polyether polyols (PEPO) are also available. Inorganic thickeners, such as, for example, bentonites or hectorite, may also be used. Such thickeners are generally employed in amounts of from about 0.1 % to 3% by weight, preferably from about 0.1 % to 1 % by weight, based on the total weight of the aqueous latex paint formulations.

[0055] In other embodiments, thickeners that also function as protective colloids may be excluded from the paint formulation. Thickeners that may be excluded include methyl cellulose, hydroxyethylcellulose, carboxymethylcellulose and polyvinyl alcohol.

[0056] For various applications, it is sometimes also desirable to include small amounts of other additives, such as bactericides, pH modifiers, and antifoamers, incorporated in the latex paint compositions herein. This may be done in a conventional manner and at any convenient point in the preparation of the latexes.

[0057] Commercially available latex paints may contain other components which serve to raise the Volatile Organic Content of the paint formulation. Volatile Organic Content of a paint formulation refers to the presence of volatile organic components; i.e., any volatile component that contains carbon and is not listed by the EPA as an exempt solvent. VOC sources may include co-solvents, including glycols, which help with wet edge application, open time, and freeze-thaw resistance, and coalescents, which help the latex polymer form a film by lowering T_g as the film dries; emulsion components and most additives at low levels. For instance, amino methyl propanol is a volatile compound used to adjust pH.

[0058] Volatile Organic Content in terms of grams per liter is calculated according to the formula set forth in the hereinbefore-mentioned U.S. Patent Publication No. 2010/0056696 which is incorporated herein by reference. Commercially available latex paints may have VOC levels higher than 150 g/L. In contrast, the coating and paint compositions described herein can have a very low volatile organic content (VOC), such as less than about 50 g/L, or even less than 5 g/L.

[0059] The VAE emulsion copolymers used as the film-forming component in the compositions herein may already be present during the dispersion of the pigment and filler. But in most cases, the copolymer blend is advantageously added to the filler/pigment paste which is still hot or also cooled, under rapid or also slower stirring.

[0060] Without being bound by theory, one feature that may affect the overall combination of properties in a latex paint formulation is the particle size range present in the emulsion. When the proportion of large particles is high, scrub resistance of coatings formed from the resulting paint may be reduced. When the proportion of fines, i.e., those particles having a size less than 0.1 micrometers, is high, the paint may have poor flow and leveling characteristics. The particle size of latex in the copolymer emulsion can be affected by adjusting the level of protective colloid or surfactant concentration added initially or incrementally during polymerization. Agitation is another variable which can affect particle size in the copolymer emulsion. These factors may be adjusted as necessary by methods known in the art. In some embodiments, the particle size of the aqueous latex- based coating component is less than 1 micrometers, e.g., less than 500 nanometers.

Coating/Paint Composition Performance

[0061] Upon curing, the copolymers in the aqueous latex coating/paint compositions herein form a film or coating which will adhere to a substrate onto which the coating/paint composition has been applied. The film or coating seals and protects the substrate.

[0062] The minimum temperature required for the copolymers in the latex to form a coating or film is referred to as the Minimum Film-Forming Temperature or MFT. MFT is related to the glass transition temperature, T_g, of the emulsion copolymers in the copolymer blend, but can also be affected by other components of such coating/paint compositions such as coalescents. The coating/paint compositions herein will preferably have a MFT of equal to or less than about 10°C, e.g., equal to or less than about 5°C. [0063] The coating/paint compositions herein will form films or coatings which exhibit excellent adhesion onto dry substrates or hard surfaces to which such compositions have been applied. The film, when dried, exhibits a wet scrub resistance ("WSR") of at least 400 cycles, e.g., at least 425 cycles, at least 435 cycles, or at least 437 cycles, as measured in accordance with a modified version of Test Method B of ASTM D 2486, referred to herein as modified Test Method B of ASTM D 2486. Test Method B of ASTM D 2486 is modified to test the wet scrub resistance without a scrub medium and without shim(s). In terms of ranges, the film, when dried, exhibits a WSR of 400 to 600 cycles, e.g., 425 to 575 cycles, 435 to 565 cycles or 437 to 560 cycles. In this Test Method, the inventive paint is measured against a reference, BATF 998A. Results are reported as cycles and are also reported as a percentage of cycles to the cycles of the reference surfactant. In terms of WSR as a function of % of the reference surfactant, the neutralized surfactant is at least 140 % of the reference, e.g., at least 145%, at least 150%, or at least 155%. In terms of ranges, the film, when dried, exhibits a WSR as a function of % of the reference surfactant of 140 to 300%, e.g., 145 to 250%, 150 to 225% or 155 to 210%.

[0064] The coating/paint compositions of the present invention, and the performance of such coating/paint compositions herein, are illustrated by way of the following non-limiting Examples.

Example 1 preparation

[0065] A 10.2 liter pressure vessel was charged with 3.5 kg water, 241 g Disponil® A 3065, 105 g phosphate A, neutralized (Rhodafac® RS 710), 88 g of aqueous 33% sodium vinyl sulphonate, 13 g sodium acetate, 1 g Bruggolit® FF6, 0.21 g Mohr's salt, 0.52 g tetra sodium EDTA and 2.1 g Agitan® 282. A 10% sodium hydroxide solution was then added until neutral pH was observed. The vessel was then evacuated and flushed with nitrogen. Stirring was then turned on.

[0066] Disponil® A 3065 is a mixture of ethoxylated linear fatty acids having 65 wt.% non-ionic surfactant. Rhodafac® RS 710 is a complex organic phosphate ester, free acid comprising polyoxyethylene tridecyl ether phosphate. The weight ratio of Disponil® A 3065 to Rhodafac® RS 71 0 is approximately 3:2. Bruggolit® FF6 is a mixture of inorganic and substituted organic acid salts.

[0067] A monomer slow addition vessel was charged with 4.7 kg vinyl acetate and 21 g trimethoxyvinyl silane.

[0068] The reactor was charged with 5% of the vinyl acetate/trimethoxyvinyl silane mixture and with 0.55 kg ethylene.

[0069] An addition vessel for a reducer was charged with a solution of 0.19 kg water and 4.2 g Bruggolit® FF6.

[0070] An addition vessel for an oxidizer was charged with a solution of 0.19 kg water and 10.5 g sodium persulphate. [0071] Polymerization was carried out at 70°C by adding the solution from the addition vessel for reducer and by adding the solution from the addition vessel for oxidizer over a period of 270 minutes, and the remaining 95 % of the monomer mixture over a period of 200 minutes. After finishing the additions, the batch was heated to 85°C, and then cooled to 60°C. The batch was transferred to a post- treatment vessel .

[0072] Post treatment of the batch was carried out by adding a reducer solution comprising 52 g water, 2 g Bmggolit® FF6 and 0.1 g Mohr's salt, and by adding an oxidizer solution comprising 52 g water and 7.5 g of an aqueous 70% solution of tert-butylhydroperoxide.

Example 2-10 Preparation

[0073] Example 2 was prepared by the same method used for example 1 , except that Phosphate A (Rhodafac® RS 710) was not neutralized.

[0074] Example 3 was prepared by the same method used for example 1 , except that a decreased amount of Phosphate A was used.

[0075] Example 4 was prepared by the same method used for example 3, except that Phosphate A was not neutralized.

[0076] Example 5 was prepared by the same method used for example 1 , except that Phosphate B, neutralized (Rhodafac® RS 610, a complex organic phosphate ester, free acid comprising polyoxyethylene tridecyl ether phosphate), was used instead of Phosphate A, neutralized.

[0077] Example 6 was prepared by the same method used for example 5, except that Phosphate B was not neutralized.

[0078] Example 7 was prepared by the same method used for example 5, except that a decreased amount of Phosphate B was used.

[0079] Example 8 was prepared by the same method used for example 5, except that Phosphate B was not neutralized.

[0080] Example 9 was prepared by the same method used for example 1 , except that Phosphate C (Polystep® A16, a branched sodium dodecylbenzene sulfonate) was used instead of Phosphate A.

[0081] Example 10 was prepared by the same method user for example 9, except that a decreased amount of Phosphate C was used. [0082] As shown below in Table 1 , when the phosphate surfactant is neutralized and when the weight ratio of non-ionic surfactant to neutralized phosphate surfactant is greater than 1 :1 , the WSR cycles increase and the WSR as a % reference surfactant increases. Each surfactant is reported as parts per hundred parts monomer ("PPHM").

TABLE 1

WET SCRUB RESISTANCE

Example Surfactant PPHM WSR WSR

Cycles [% BATF 998A]

1 Phosphate A, 2 503 185

Neutralized

2 Phosphate A 2 248 91

3 Phosphate A, 1 427 157

neutralized

4 Phosphate A 1 291 107

5 Phosphate B, 2 549 202

neutralized

6 Phosphate B 2 6 2

7 Phosphate B, 1 439 161

neutralized

8 Phosphate B 1 567 208

9 Phosphate C 1 280 103

10 Phosphate C 2 381 140

[0083] While the illustrative embodiments of the disclosure have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of the patentable novelty which reside in the present disclosure, including all features which would be treated as equivalents thereof by those skilled in the art to which the disclosure pertains.

Claims

We Claim:

1 . An aqueous latex-based coating component, comprising:

(a) a copolymer of at least a vinyl ester of a C1-13 alkanoic acid and ethylene;

(b) a non-ionic surfactant; and

(c) a neutralized phosphate surfactant,

wherein the weight ratio of non-ionic surfactant to neutralized phosphate surfactant is greater than 1 :1 , preferably from 1 :1 to 3:1 , most preferably approximately 3:2.

2. The component of Claim 1 , wherein the vinyl ester is vinyl acetate.

3. The component of Claim 2, wherein the copolymer comprises the emulsion polymerization product of from 70 wt% to 95 wt% vinyl acetate, from 5 wt% to 30 wt% ethylene, and from 0 wt% to 10 wt% of auxiliary co-monomers.

4. The component of Claim 3, wherein the vinyl acetate, ethylene and auxiliary co-monomers are polymerized in the presence of the non-ionic surfactant and the neutralized phosphate surfactant.

5. The component of any of the preceding claims, comprising the copolymer in an amount from 1 to 20 wt.%, preferably from 3 to 12 wt.%.

6. The component of any of the preceding claims, wherein the phosphate surfactant is a CMS ester of phosphoric acid.

7. The component of any of the preceding claims, wherein the phosphate surfactant comprises from 4 to 20 ethylene oxide units, preferably from 6 to 10 ethylene oxide units.

8. The component of any of the preceding claims, wherein the phosphate surfactant is neutralized with sodium hydroxide.

9. The component of any of the preceding claims, wherein the non-ionic surfactant comprises ethoxylated linear fatty alcohols.

10. The component of any of the preceding claims, wherein the non-ionic surfactant comprises a reduced, branched or linear C1 -C50 ether or ester comprising 4 to 100 ethylene oxide units.

1 1 . The component of any of the preceding claims, wherein the composition is substantially free of protective colloids.

12. The component of any of the preceding claims, wherein the composition is substantially free of hydroxyethyl cellulose and polyvinyl alcohol.

13. The component of any of the preceding claims, wherein the composition has an average particle size less than 1 micrometer, preferably less than 500 nanometers.

14. The component of any of the preceding claims, wherein the copolymer is substantially free of unesterified carboxyl moieties.

15. The component of any of the preceding claims, wherein the copolymer comprises at least one auxiliary co-monomer selected from the group consisting of unsaturated silane co-monomers, glycidyl co-monomers, cyclic ureido co- monomers and combinations thereof, preferably wherein the at least one auxiliary co-monomer is selected from the group consisting of vinyl trial koxysilane monomers, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, vinyl glycidyl ether, vinyltoluenes and styrenes substituted with a glycidyl radical in the aromatic moiety, vinylbenzoates substituted with a glycidyl radical in the aromatic moiety, and combinations thereof.

16. The component of any of the preceding claims, further comprising at least one auxiliary component selected from the group consisting of wetting agents, dispersants, emulsifiers, fillers, thickeners, antifoams, dyes and preservatives.

17. The component of any of the preceding claims, further comprising calcium carbonate.

18. The component of any of the preceding claims, wherein the composition is substantially free of alkylphenol ethoxylates.

19. The component of any of the preceding claims, wherein the copolymer blend has a Minimum Film-Forming Temperature (MFT) of equal to or less than 10°C, preferably equal to or less than 5°C.

20. A paint composition, comprising:

(i) the aqueous latex-based coating component of any of the preceding claims;

(ii) a pigment component selected from inorganic pigments, inorganic fillers and mixtures thereof present in an amount such that the paint composition has a pigment volume concentration (PVC) of from 25 vol% to 90 vol%, preferably from 75 vol% to 90 vol%; and

(ii) at least one auxiliary component selected from the group consisting of wetting agents, dispersants, emulsifiers, fillers, thickeners, antifoams, dyes and preservatives.

21 . The paint composition of any of Claim 20, having a volatile organic content (VOC) of less than 50 g/L, preferably less than 5 g/L.

22. The paint composition of any of Claims 20-21 , which when dried forms a film exhibiting a wet scrub resistance of at least 400 cycles as measured in accordance with modified Test Method B of ASTM D 2486.