MXPA01000643A - Aqueous composition - Google Patents

Abstract

Aqueous dispersions of copolymers formed by the polymerisation of a monomer mixture comprising 0.05%to less than 4.5%by weight of certain terminally unsaturated oligomers are useful for improving the scrub resistance, corrosion resistance, opacifying capacity and/or efflorescence resistance of a coating.

Description

AQUEOUS COMPOSITION FIELD OF THE INVENTION This invention relates to an aqueous composition. More particularly, the present invention relates to an aqueous composition comprising, a copolymer of a terminally unsaturated oligomer dispersed or dissolved therein. BACKGROUND OF THE INVENTION Aqueous-based coatings, such as for example latex or emulsion polymers containing paints, constitute a significant segment of all the coatings that are currently used. Water-based coatings offer the advantages of being generally easier to use than conventional oil-based coatings, such as for example alkyd paints, and contain little or no undesirable volatile organic solvent. Water-based coatings formulators wish to match or improve the performance properties of alkyd-based paints, which include for example friction resistance, corrosion resistance, efflorescence resistance, blocking resistance, dust pick-up resistance, resistance to stickiness, resistance to usual wear, resistance to printing, resistance to tension and opacification capacity. Although it may be highly desirable for a paint to demonstrate maximum performance for all relevant properties, in reality such paints can not be achieved, for example a paint with maximum resistance to pick up dust may also not be able to demonstrate maximum resistance to stress. Instead, formulators tend to provide optimized paints, which are paints that have a compromise of several desirable properties, for example a paint with good dust pick-up resistance may be able to demonstrate resistance to average stress. A formulator can modify the properties of a particular coating by adjusting its composition, such as by changing the particular amounts of the components and / or by changing the composition of those components. Aqueous dispersions or aqueous solutions of carboxylic acid containing polymers are known to have many applications, including the use as binders in coating compositions. Typically, these polymers are formed from the polymerization of a mixture of ethylenically unsaturated monomers comprising up to 20%, typically 0.05% to 10%, by weight of a carboxylic acid containing monomers, such as acrylic acid (AA) or acid methacrylic (MAA). The properties of a coating comprising such polymers can be modified by changing the mixture of monomers to be polymerized to form a particular polymer and / or by using two or more different polymers and / or by using multi-stage polymers (eg core / shell). , as described for example in US-A-4193902, EP-A-0466409, EP-A-0612805, EP-A-0694564 and EP-A-0741173. OA-9532228 and OA-9532255 describe each coatings aqueous containing a binder based on a graft copolymer comprising from 2 to 98%, preferably from 60 to 95%, more preferably from 60 to 85%, by weight of a polymeric base of polymerized ethylenically unsaturated monomers and from 98 to 2% , preferably from 40 to 5%, more preferably from 40 to 15%, by weight of macromonomers attached to the polymeric base at a single terminal point of the macromonomer, the macromonomer having several average molecular weights of 500 to 30,000 'and comprising from 5 to 100%, preferably at least 10% and more preferably from 20 to 40%, by weight of macromonomers, of ethylenically unsaturated polymerized alpha-beta monomers having carboxylic acid functionalities or instead amine functionalities and wherein at least a portion of the carboxylic acid or amino groups has been neutralized and wherein the macromonomers are soluble or dispersed in aqueous vehicle to stabilize the portion of the graft polymer that forms an insoluble particle. The graft copolymer is described to have an average molecular weight of up to 500, 000 with a more preferred average molecular weight substantially less than 500,000 for example up to 300,000. Graft copolymers are described to be useful as film forming carriers in the preparation of coating compositions in water such as, for example, base coat or clear coat compositions useful in automotive applications. There is a continuing desire by the formulators to provide aqueous coatings that demonstrate improved performance, such as resistance to friction, corrosion resistance and / or resistance to efflorescence, over other aqueous coatings. Therefore, it is an object of this invention to provide aqueous compositions that are particularly, but not exclusively, useful as performance enhancing binders for aqueous coatings. In particular, although not exclusively, it is the object of this invention to provide aqueous coatings to improve at least one of the following properties of an aqueous coating: friction resistance, corrosion resistance, blooming resistance and opacification ability. According to the present invention, there is provided an aqueous composition comprising, dispersed or dissolved therein, a copolymer formed by polymerization, preferably by emulsion polymerization, of a monomer mixture consisting of: a) from 0.05 to less than 4.5 % by weight of one or more terminally unsaturated oligomers of the formula: CH2 = C - [- N-] n - [- M -] m - H - x x where N is the residue of an ethylenically unsaturated monomer of the formula: - CH2 - CZ - COOY wherein M is the residue of a ethylenically unsaturated monomer other than N; wherein the N and M residues are randomly ordered in the oligomer; where m is the total number of residues M in the oligomer and is in the range of 0 to 75; where n is the total number of residues N in the oligomer and is in the range of 3 to 150; where n is equal to or greater than m and the sum of n and m is in the range of 3 to 150; wherein X and each Y are independently selected from the group consisting of H, NH 4, alkali metals and alkaline earth metals; and wherein each Z is independently selected from the group consisting of H and CH3; b) greater than 85.5 to 99.95% by weight of at least one monomer selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids containing 1 to 20 carbons, vinyl aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one double bond olefinic; and c) 0 or up to 10% by weight of one or more copolymerizable monomers. According to another aspect of the present invention, there is provided a method for improving the performance of a coating, wherein the method comprises I) applying to a substrate an aqueous coating composition comprising, dispersed or dissolved therein, a copolymer formed by polymerization, preferably emulsion polymerization, of a monomer mixture consisting of: a) from 0.05 to less than 4.5% by weight of one or more terminally unsaturated oligomers of the formula: coox wherein N is the residue of an ethylenically unsaturated monomer of the formula: -CH2-CZ- | COOY where M is the residue of an ethylenically unsaturated monomer other than N; wherein the N and M residues are randomly ordered in the oligomer; where m is the total number of residues M in the oligomer and is in the range of 0 to 75; where n is the total number of residues N in the oligomer and is in the range of 3 to 150; where n is equal to or greater than m and the sum of n and m is in the range of 3 to 150; wherein X and each Y are independently selected from the group consisting of H, NH, alkali metals and alkaline earth metals; and wherein each Z is independently selected from the group consisting of H and CH3; greater than 85.5 to 99.95% by weight of at least one monomer selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids containing 1 to 20 carbons, vinyl aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and c) 0 or up to 10% by weight of one or more copolymerizable monomers; and II) drying the aqueous coating composition to form the coating. Surprisingly, coatings formed from aqueous coating compositions comprising the above-defined aqueous compositions can demonstrate superior performance not only over coatings formed from conventional aqueous coating compositions based on copolymers that do not comprise an oligomeric component but also over those formed from aqueous coating compositions based on copolymers comprising greater amounts of oligomeric component (macromonomer). The term "residues N and M are randomly ordered in the oligomer" as used in the definition of the terminally unsaturated oligomers a) means that the residue adjacent to the terminally unsaturated residue can be either an N or an M residue., that the residue adjacent to the adjacent residue of the terminally unsaturated residue can be either a N or an M residue and so on. The terminally unsaturated oligomers a) are known in the art. Suitable processes for the preparation of the oligomers a) are described, for example, in US-A-4056559, US-A-5710227, US-A-5587431, US-A-4680352, US-A-4694054 and EP- 0779305. In the terminally unsaturated oligomers a) X is preferably H. In the terminally unsaturated oligomers a) Y is preferably H. In the terminally unsaturated oligomers a) Z is preferably H. In the terminally unsaturated oligomers a) M is preferably a residue of the formula: -CH2-CX1-R wherein Xx is -H or -CH3, R is a phenyl radical, a vinyl radical, -CONH2, -CN or -COOX2, X2 is H, an alkyl radical (Cx to C8), a radical vinyl or an alkyl radical. More preferably, M is a residue of one or more ethylenically unsaturated monomers selected from the group consisting of methylacrylate, ethyl acrylate, butyl acrylate, ethylexyl acrylate, styrene, isoprene, butadiene, vinyl acetate, acrylamide, acrylonitrile, allyl methacrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate. In the terminally unsaturated oligomers a), the n: m ratio is preferably in the range of 1: 0 to 3: 1, more preferably 1: 0 to 9: 1. More preferably, the ratio of n: m is 1: 0. In the terminally unsaturated oligomers a), m is preferably in the range of 0 to 9 and n is preferably in the range of 3 to 50. More preferably, m is 0 and n is in the range of 3 to 25. The monomers suitable b) are alkyl (meth) acrylates (Ci to C2>, preferably alkyl (meta) acrylates) (C? -C8), more preferably methyl methacrylate, ethyl methacrylate, ethyl acrylate, butyl acrylate, butyl methacrylate and 2-ethylexyl acrylate. The amides of acrylic and methacrylic acid are preferably acrylamides. The vinyl esters of carboxylic acids with from 1 to 20 carbons are preferably vinyl laurate, vinyl stearate, vinyl propionate and vinyl acetate, more preferably vinyl acetate. Vinyl aromatic compounds containing up to 20 carbons are preferably vinyl toluene, styrene, methylstyrene, butyl styrene and decylstyrene, more preferably styrene. Ethylenically unsaturated nitriles containing from 3 to 6 carbons are preferably acrylonitrile and methacrylonitrile. The vinyl halides are preferably vinyl chloride and vinylidene chloride. The non-aromatic hydrocarbons with 2 to 8 carbons and at least one olefinic double bond are preferably butadiene, isoprene and chloroprene. The monomers b) are preferably selected from the group consisting of methyl (meta> acrylate, ethyl (meta) acrylate, butyl (meta) crylate, 2-ethylexyl (meta) acrylate, decyl (meta) acrylate, lauryl (meta) acrylate , isobornyl (meta) acrylate, isodecyl (meta) acrylate, oleyl (meta) acrylate, palmityl (metha) acrylate, sterile (meta) acrylate, ethylene, butadiene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide and glycidyl methacrylate The monomer mixture which polymerizes to form the copolymer optionally comprises up to 10% by weight of other c) copolymerizable monomers. Other suitable copolymerizable monomers are preferably selected from the group consisting of hydroxyethyl (meta) acrylate, hydroxypropyl (meta) acrylate, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mono-methyl itaconate, mono-methyl fumarate, mono -butyl fumarate, maleic anhydride, phospho-ethyl methacrylate, glycidyl (meta) acrylates, susbtituted acrylamides, diacetone acrylamide, glycidyl (meta) acrylates, glycidyl methacrylate, acetoacetoxy ethyl methacrylate, acrolein, methacrolein, dicyclopentadienyl methacrylate, dimethyl meta-isopropenyl benzyl isocyanate, isocyanate ethyl methacrylate, methyl cellulose, hydroxyethyl cellulose, ethylene, propylene, N-vinyl pyrrolidone, N, N'-dimethylamino (meta) acrylate and polymerizable surfactants, including but not limited to Trem LF-40 available from Henkel Corp. Preferably copolymers have an average molecular weight of above 500,000, more preferably above 750, 000 and more preferably above 1,000,000, as measured by gel permeation chromatography. Preferably the copolymers have a glass transition temperature (Tg) in the range of from -10 to 120 ° C, preferably from -5 to 40 ° C, as measured by Differential Scanning Calorimetry. The monomer mixture that is polymerized to form the copolymer preferably comprises from 0.1 to less than 4.5%, more preferably from 1.0 to less than 4.5% by weight of the oligomer a) terminally unsaturated. The monomer mixture preferably comprises 4%, or less, more preferably 3% or less, and still more preferably 2% or less, by weight of the oligomer a) terminally unsaturated. The monomer mixture that polymerizes to form the copolymer preferably comprises more than 95.5%, more preferably 96% or more, more preferably 97% or more, and still more preferably 98% or more, by weight of monomer b). The above copolymer is preferably a latex in which the particles of the dispersion preferably have an average diameter of no more than 250 nm, more preferably no greater than 150 nm, and more preferably no greater than 125 nm. In one embodiment of the present invention, the dispersion particles have an average diameter of not more than 100 nm. The dispersion of the above copolymer can be formed by any emulsion polymerization technique suitable for emulsion polymerization of monomer mixtures comprising less than 4.5% by weight of mono- or dicarboxylic acid monomer. Such techniques are well known in the art. For example, the emulsion polymerization process described in US-A-5356968 is very suitable for the preparation of the polymer dispersions of the present invention. The dispersion of the copolymer according to the present invention can be used in the preparation of aqueous dispersions having a multimodal particle size distribution, for example bimodal. Accordingly, in a further aspect of the present invention, there is provided an aqueous composition comprising a dispersion of polymer particles having a muiti-modal particle size distribution, wherein at least one mode of the distribution of The multi-modal particle size is attributed to a dispersion of the polymer particles comprising a copolymer formed by the emulsion polymerization of a monomer mixture comprising: a) from 0.05 to less than 4.5% by weight of one or more oligomers terminally unsaturated formula: CH2 = C - [- N-] n - [- M -] m -H coo x wherein N is the residue of an ethylenically unsaturated monomer of the formula: -CH2-CZ-I COOY wherein M is the residue of an ethylenically unsaturated monomer other than N; wherein the N and M residues are randomly ordered in the oligomer; where m is the total number of residues M in the oligomer and is in the range of 0 to 75; where n is the total number of residues N in the oligomer and is in the range of 3 to 150; where n is equal to or greater than m and the sum of n and m is in the range of 3 to 150; wherein X and each Y are independently selected from the group consisting of H, NH, alkali metals and alkaline earth metals; and wherein each Z is independently selected from the group consisting of H and CH3; b) greater than 85.5 to 99.95% by weight of one or more monomers selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids which contain from 1 to 20 carbons, vinyl aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and c) 0 or up to 10% by weight of one or more copolymerizable monomers. Preferably, at least one mode of the multi-modal particle size distribution is attributable to a dispersion of the polymer particles having an average particle diameter of from 40 to 150 nm. Preferably, a portion of the polymer particles within at least one mode having an average particle diameter of from 40 to 150 nm are copolymer particles. In a particular embodiment, at least one mode of the multi-modal particle size distribution is attributable to a dispersion of the polymer particles having an average particle diameter of from 40 to 100 nm. of which a larger portion of the polymer particles within at least one mode are copolymer particles. The aqueous dispersion having a multi-modal particle size distribution can be bi-modal, or it can comprise more than two modes. The preparation and use of multi-modal emulsion polymers is well known in the art, for example as described in US-A-4539361 and US-A-5624992. The aqueous dispersions of the present invention can be prepared with high content of polymer solids.

For example, an aqueous dispersion of the present invention comprising polymer particles having multi-modal particle size distribution may comprise 70% or more, for example up to 75%, by weight polymer solids.

Accordingly, the aqueous dispersions of the present invention preferably comprise from 40 to 75% by weight of polymer solids, more preferably from 55 to 75% by weight polymer solids. The aqueous compositions can be used in or as coatings, such as paints, initiators and varnishes, adhesives for non-woven fabrics and textiles, electronic chemistries, powder coatings, dispersants such as pigment dispersants, paper coatings, metal coatings, skin, adhesives, floor polishers, waterproofing and elastomeric mastics for walls. The dispersions can be used alone or in combination with one or more polymer dispersions. Preferably, aqueous compositions are used in paints to improve their performance properties. For example, the aqueous compositions of the present invention are useful for improving the resistance of a coating to friction, the resistance of a coating to corrosion, the ability of a coating to opacify, and / or the strength of a coating to the efflorescence The aqueous compositions of the present invention are preferably used in or as architectural coatings such as interior and exterior house paints, including masonry paints, coatings and wood treatments, floor polishers, maintenance coatings such as coatings on metal substrates, and traffic paints such as those paints used to mark roads, pavements and tracks. In a preferred embodiment, the present invention includes a method for coating a substrate, wherein the substrate is a wall, floor or roof of a construction. In addition to the copolymer, the aqueous compositions of the present invention may include other optional components. Such other optional components include, but are not limited to, other polymers, surfactants, extenders, pigments and inks, perleascents, adhesion promoters, crosslinkers, dispersants, defoamers, leveling agents, optical brighteners, UV stabilizers, coalescers, rheology modifiers and antioxidants In a preferred embodiment, the present invention provides an aqueous composition comprising, dispersed or dissolved therein, I) a copolymer formed by polymerization, preferably by emulsion polymerization, of a monomer mixture consisting of: a) from 0.05 to less 4.5% by weight of one or more terminally unsaturated oligomers of the formula: coo x wherein N is the residue of an ethylenically unsaturated monomer of the formula: -CH 2 -CZ-C IOOY wherein M is the residue of an ethylenically unsaturated monomer other than N; wherein the N and M residues are randomly ordered in the oligomer; where m is the total number of residues M in the oligomer and is in the range of 0 to 75; where n is the total number of residues N in the oligomer and is in the range of 3 to 150; where n is equal to or greater than m and the sum of n and m is in the range of 3 to 150; wherein X and each Y are independently selected from the group consisting of H, NH 4, alkali metals and alkaline earth metals; and wherein each Z is independently selected from the group consisting of H and CH3; greater than 85.5 to 99.5% by weight of at least one monomer selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids containing 1 to 20 carbons, vinyl aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and c) 0 or up to 10% by weight of one or more copolymerizable monomers; and II) an inorganic particulate material. Preferably the inorganic particulate material is selected from the group consisting of pigments, extenders and other inorganic particulate materials used in paint compositions and initiators. Examples of such inorganic particulate materials include for example titanium dioxide, clays, carbonates and silicates. The preferred inorganic pigment is titanium dioxide. In this particular embodiment the proportion of component I) to component II) is preferably in the range of 1:10 to 10: 1. Such compositions are particularly suitable for use in or as paints, primers or primers. The invention will now be described more specifically in terms of the following examples of some preferred embodiments that are given solely for purposes of illustration and can be contrasted with the comparative tests also given below. EXAMPLES I. Preparation of Oligomers Preparation of Oligomer "A" Oligomer A is a terminally unsaturated oligomer of acrylic acid prepared according to the procedures described in US 5,710,227. Oligomer A was prepared at 29% solids in water, with average molecular weight, Mw, of 1199; and various average molecular weights, Mn, of 485. Preparation of Oligomer "B" Oligomer B is a terminally unsaturated oligomer of acrylic acid prepared according to the procedures described in US 5,710,227. Oligomer B was prepared at 55.3% solids in water, with average molecular weight of Mw, of 1015; and several average molecular weights, Mn, of 400. Preparation of the WC Oligomer "The oligomer C is a terminally unsaturated oligomer of acrylic acid prepared according to the procedures described in US 5,710,227 The oligomer C was prepared at 29.2% solids in water, with average molecular weight of Mw, of 1511, and several average molecular weights, Mn, of 590. II Preparation of Emulsion Polymers Nos.1-5; Preparation of Copolymer No.l ("Oligomer A" to 2.5 %) A mixture of monomers was prepared by the combination of 295g of deionized water, 21.3g of an aqueous solution of a 30% polyethoxylated alkyl sulfate, 423g of methyl methacrylate, 428g of butyl acrylate and 76.3g of an aqueous solution at 29 ° C. % of Oligomer A. The monomer mixture was emulsified when mixed under standard conditions, 580g of deionized water and 15g of polyethoxylated alkyl sulfate were charged to a three liter flask and the contents were heated to 82-84 ° C. to the 50g flask of the emulsified monomer mixture, followed by 18.4 g of an aqueous solution of 18.5% ammonium persulfate. The monomeric mixture and 49g of an aqueous solution of 3.7% ammonium persulfate was added linearly and separately to the flask for 180 minutes while maintaining the temperature of the contents at 82-84 ° C. After the additions were completed, the contents of the flask were cooled to 60 ° C. Any remaining monomer was reduced by the addition of aqueous ferrous sulfate, aqueous tertiary butyl hydroperoxide and isoascorbic acid. The polymer was neutralized to a pH of 9.1 with ammonia. The product was diluted with deionized water to provide a polymer solids level of 44.6% by weight. The latex had a particle size of 91nm and a viscosity of 100 cps. Preparation of Copolymer No.2 ("Oligomer A" 1.5%) Copolymer No.2 was prepared identically as Copolymer No.l. In this case, 45.7 g of a 29% aqueous solution of Oligomer A and 315 g of deionized water were added to prepare the monomer mixture. The polymer was neutralized to a pH of 9.7 with ammonia. The product was diluted with deionized water to provide a polymer solids level of 44.2% by weight. The latex had a particle size of 90 nm and a viscosity of 80 cps. Preparation of Copolymer No.3 ("Oligomer A" at 4.0%) Copolymer No.3 was prepared identically as Copolymer No.l. In this case, 122g of a 29% aqueous solution of Oligomer A, 410g of methyl methacrylate and 261g of deionized water were added to prepare the monomer mixture. The polymer was neutralized to a pH of 9.4 with ammonia. The product was diluted with deionized water to provide a polymer solids level of 43.6% by weight. The latex had a particle size of 98 nm and a viscosity of 67 cps. Preparation of Copolymer No.4 ("Oligomer A" at 1.0%) Copolymer No.4 was prepared identically as Copolymer No.l. In this case, 30.5 g of a 29% aqueous solution of Oligomer A, 425 g of methyl methacrylate, 437 g of butyl acrylate and 326 g of deionized water were added to prepare the monomer mixture. The polymer was neutralized to a pH of 9.7 with ammonia. The product was diluted with deionized water to provide a polymer solids level of 43.0% by weight. The latex had a particle size of 90 nm and a viscosity of 43 cps. Preparation of Copolymer No.5 (Comparison of MAA to 2.5%) This latex polymer was prepared in a conventional manner (see, for example, U.S. Patent 5,356,968). A monomer mixture was prepared by combining 348g of deionized water, 21.3g of an aqueous solution of a polyethoxylated alkyl sulfate, 425g of methyl methacrylate, 426g of butyl acrylate and 22g of methacrylic acid. The monomer mixture was emulsified when mixed under standard conditions. To a three-liter flask was charged 58Og of deionized water and 15g of polyethoxylated alkyl sulfate and the contents were heated to 82-84 ° C. 50g of the emulsified monomer mixture was charged to the flask, followed by 18.4g of an 18.5% aqueous solution of ammonium persulfate. The monomeric mixture and 49g of a 3.7% aqueous solution of ammonium persulfate were added linearly and separately to the flask for 180 minutes while maintaining the temperature of the contents at 82-84 ° C. Any remaining monomer was reduced by the addition of aqueous ferrous sulfate, aqueous tertiary butyl hydroperoxide and isoascorbic acid. The polymer was neutralized to a pH of 9.2 with ammonia. The product was diluted with deionized water to provide a polymer solids level of 43.9% by weight. The latex had a particle size of 89nm and a viscosity of 30 cps. III. Preparation of Semi-gloss Coatings Compositions Nos.1-5 For comparative purposes, semi-gloss compositions were prepared according to the following formulations. Tamol 681 is a dispersant available from Rohm and Haas Company. Ti-Puré R-900 is a titanium dioxide of rutile coating grade, available from DuPont de Nemours Co. Foamaster VL is an antifoam available from Henkel Corp. Texanol is a co-solvent, available from Eastman Kodak Co. Triton GR-7 is a surfactant available from Union Carbide Co. Acrysol 1020 NPR and Acrysol RM-825 are thickeners, both available from Rohm and Haas Company. Semi-gloss coating compositions were prepared comprising each of the above copolymers. The semi-gloss coating compositions were prepared by Formulation No.l. For Paint Compositions No. 1-5, the ground pigment for each paint is the same. The dilutions varied by the amounts of thickener to obtain a low slip final viscosity of 90-100 KU. The final paintings were 25.2% pigment volume concentration / 32.8% solids volume. Formulation No .1 Material Grams Propylene Glycol 30. 00 Tamol 681 (35%) 7. 67 Foamaster VL 5. 00 Water 10. 00 Ti Pure R-900 134.13 The above ingredients were ground for 20 minutes in a high speed disperser. The grind was diluted at a slower speed with the following materials: Copolymer No. 1-5 264.00 Texanol 12.20 Foamaster VL 5.00 Triton GR-7M 1.00 Acrysol RM-1020 NPR See Table 1 Acrysol RM-825 See Table 1 Water 52.00 Totals 525.10 PVC: 25.17 Vol. Solids: 32.80 Kg / liters: 1.29 Solid weight: 47.82 Table 1 Thickener levels used in Formulation No. 1 - twenty-one Each semi-gloss paint composition was then evaluated for the paint properties. The results of the evaluation properties of each worked paint of the corresponding copolymer are shown in the Table 2. The test methods are described below.

IV. Test Methods: 1. Acceptance of Color Paints for these series were stained with 113.4g / 3.78541 (4 oz / gal) of phthalo blue dye. A film with 7.5 x 103cm (3 mil) was applied with Bird applicator on a white card. The applications (DD) were allowed to dry overnight at controlled room temperature (25 ° C / 50% relative humidity). Paint was applied to a 7.5 cm x 7.5 cm (3 inch x 3 inch) section of the dry paint film with a 2.5 cm (1 inch) nylon brush. The paint was brushed (BO) on the surface with a dry brush until the applied paint had a wear by brushing as indicated by the film that became sticky. The applied film was allowed to dry overnight under the same conditions as before. The reflectance Y was measured with a Hunter Lab Ultra Sean XE spectrophotometer on the application (DD) and the brushed areas (BO) of the film. The difference in the Y reflectance between the application and the brushed areas was calculated. The acceptance of the optimal color was made when the difference between the application and the brushed areas was zero. The closest to zero is the value, better is the acceptance of color. From Table 2 it can be seen that the paints made from copolymers 1-4 had significantly better color acceptance. These paints were made from binders stabilized with the oligomer. The paints made from the copolymers 4 had an extraordinarily good color acceptance. This copolymer had the lowest level of oligomer. 2. Friction Resistance Friction resistance was measured with a Deformation Line Washability / Abrasion Machine from Gardner Laboratory Inc. Paints were applied on black vinyl panels Type P-121-10N, (Leneta Co.) with a Dow film applicator of 17.5 x 10 ~ 3cm (7 mil). The applications were allowed to dry for 7 days at controlled room temperature 25 ° C / 50% relative humidity. The applications were rubbed with the Abrasion Machine. The nylon brush was impregnated in water for 24 hours before the test. A wedge of 25 x 10 ~ 3cm (10 mil) was used. L0g of abrasive friction medium Type SC-2 (Leneta Co.) Was applied to the brush at the beginning of the test and after 400 cycles. Five millimeters of water were added to the brush after 400 cycles. The number of cycles of friction required up to the first cut of the film that exposed the vinyl substrate was recorded for each application and subsequently a continuous line of the width of the wedge was cut through the film. Films that required more friction cycles to cut through the film were more resistant to friction. The results in Table 2 show the increases in friction resistance as the amount of oligomer in the copolymer decreases. At equal acid levels, the paints made from copolymer No. 1 vs those from copolymer No. 5, the frictional resistance of the paint made from copolymer No. 1 (stabilized with the oligomer) was 30% more than the control. The paint made of copolymer No.4 had 68% greater frictional resistance than the comparative paint of copolymer No.5 and 30% higher than the paint made from copolymer No.l. 3. Thickener Demand The amount of thickener required to formulate each paint at a desired common viscosity was recorded. It is a cost advantage to use the minimum amount of thickener to achieve the desired viscosity. As shown in Table 2, lower thickener was required for copolymers with lower levels of oligomer. At the same acid levels, copolymer No. 1 vs copolymer No 5, the copolymer made with the thickening oligomer A was significantly more efficient than the control. This advantage was greater even at the lowest level of oligomer. 4. Stability - Syneresis After the phthalo blue dye was added to the paints, the paints were kept at room temperature for 24 hours. After this time, the paintings were evaluated visually for evidence of syneresis. Any syneresis in mm was measured. As shown in Table 2 all copolymers with oligomer A had less syneresis than the comparative paint made of copolymer No.5. The dyed paints made from the copolymers with the lowest oligomer levels did not have syneresis. 5. Scattering Coefficients On transparent glass plates, 4 films of 25 cm x 30 cm x 0.625 cm (10"x 12" x 0.25") were applied for each sample Triple applications were made with the Bird applicator of 3.75 x 10"3 cm (1.5 thousand) and a single application of 0.1 cm (40 thousand). The applications were allowed to dry for 7 days at a controlled room temperature (25 ° C / 50% relative humidity). The dried films were scratched with a 6.25 cm x 15 cm (2.5"x 6") pattern using an excel blade. Five reflectance values were measured in the scratched areas with a portable Gardner Reflectometer. The scratched areas of the plate were removed, placed on a scale weighing pan without calibrating, and dried at 120 ° C overnight. The weight of this dry film was obtained. The dispersion coefficient was calculated from the Kubelka-Munk equation. The higher the coefficient, the greater the opacity of the film. The results of Table 2 show the increases of the dispersion coefficient as the level of oligomer in the copolymer decreases. The higher dispersion coefficient shows a greater coverage in the dry films. From Table 2 it can be seen that semi-gloss coatings employing copolymers 1-4 demonstrate a superior balance of properties over semi-gloss coatings formed from conventional MAA-based compositions (Copolymer No.5), particularly with respect to the resistance to friction and the acceptance of color. Similarly, by extrapolation, it can be derived that the coatings formed from the compositions wherein the oligomer content in the copolymer is 4.5% or more will not have the same superior balance of properties exhibited by the coatings formed by the method of the present invention. V. Preparation of Emulsion Polymers Nos.6-9: Preparation of Copolymer No.6 (Comparison of MAA to 1.3%) A monomeric mixture was prepared by combining 575g of deionized water, 7.1 of sodium lauryl sulfate (28% active) , 1061g of methyl methacrylate, 912g of butyl acrylate and 26.2g of methacrylic acid. The monomer mixture is emulsified by mixing under standard conditions. A 970 g five-liter flask was charged to the deionized deionized water and the contents heated to 87 ° C. 60.7g of sodium lauryl sulfate (28% active), 100.8g of the emulsified monomer mixture, 7.8g of sodium persulfate and HOg of deionized water were added to the flask. The monomer mixture was added linearly to the flask for 90 minutes while maintaining the temperature of the contents at 80-82 ° C. When the addition was complete, 37g of deionized water was added and the flask was cooled. The remaining monomers were reduced by the addition of aqueous ferrous sulfate heptahydrate, tertiary butyl hydroperoxide and sodium formaldehyde sulfoxylate. After the reaction mixture was cooled to room temperature, the polymer was neutralized to a pH of 9.4 with ammonia. The isolated product had a solids level of 48.9% by weight. The latex had a particle size of 95 nm. Preparation of Copolymer No.7 (Comparative of AA at 1.1%) A monomer mixture was prepared by combining 575g of deionized water, 24.6 of sodium lauryl sulfate (28% active), 1066g of methyl methacrylate, 912g of butyl acrylate and 22g of acrylic acid The monomer mixture is emulsified by mixing under standard conditions. A 970 g five-liter flask was charged to the deionized deionized water and the contents heated to 87 ° C. 4. Og of sodium lauryl sulfate (28% active), 100.8 g of the emulsified monomer mixture, 7.8 g of sodium persulfate and HOg of deionized water were added to the flask. The monomer mixture was added linearly to the flask for 90 minutes while maintaining the temperature of the contents at 80-82 ° C. During the reaction, 260g of deionized water was added to the flask. When the addition was complete, 37g of deionized water was added and the flask was cooled. The remaining monomers were reduced by the addition of aqueous ferrous sulfate heptahydrate, tertiary butyl hydroperoxide and sodium formaldehyde sulfoxylate. After the reaction mixture was cooled to room temperature, the polymer was neutralized to a pH of 9.4 with ammonia. The isolated product had a solids level of 51.8% by weight. The latex had a particle size of 150 nm. Preparation of Copolymer No.8 (1.1% Oligomer B) A monomer mixture was prepared by combining 570g of deionized water, 23.6g of sodium lauryl sulphate (28% active), 1024g of methyl methacrylate, 876g of butyl acrylate and 21g of an aqueous solution of Oligomer B at 55.3%. The monomer mixture is emulsified by mixing under standard conditions. A 970 g five-liter flask was charged to the deionized deionized water and the contents heated to 87 ° C. 4. Og of sodium lauryl sulfate (28% active) was added to the flask., 22.5g of deionized water, 0.96g of sodium lauryl sulfate (28% active), 35.7g of butyl acrylate, 41.7g of methyl methacrylate, 1.0 of acrylic acid, 7.8g of sodium persulfate and HOg of deionized water. The monomer mixture was added linearly to the flask for 90 minutes while maintaining the temperature of the contents at 80-82 ° C. During the reaction 260g of deionized water was added to the flask. When the addition was complete, 37g of deionized water was added and the flask was cooled. The remaining monomers were reduced by the addition of aqueous ferrous sulfate heptahydrate, tertiary butyl hydroperoxide and sodium formaldehyde sulfoxylate. After the reaction mixture was cooled to room temperature, the polymer was neutralized to a pH of 9.4 with ammonia. The isolated product had a solids level of 48.7% by weight. The latex had a particle size of 154 nm. Preparation of Copolymer No.9 (Comparison of AA at 0.74%) A monomer mixture was prepared by combining 575g of deionized water, 24.6g of sodium lauryl sulphate (28% active), 1075g of methyl methacrylate, 911g of butyl acrylate and 14.8g g of acrylic acid. The monomer mixture is emulsified by mixing under standard conditions. A 970 g five-liter flask was charged to the deionized deionized water and the contents heated to 87 ° C. 4. Og of sodium lauryl sulfate (28% active), 102 g of the emulsified monomer mixture, 7.8 g of sodium persulfate and HOg of deionized water were added to the flask. The monomer mixture was added linearly to the flask for 90 minutes while maintaining the temperature of the contents at 80-82 ° C. During the reaction 260g of deionized water was added to the flask. When the addition was complete, 36g of deionized water was added and the flask was cooled. The remaining monomers were reduced by the addition of aqueous ferrous sulfate heptahydrate, tertiary butyl hydroperoxide and sodium formaldehyde sulfoxylate. After the reaction mixture was cooled to room temperature, the polymer was neutralized to a pH of 9.4 with ammonia. The isolated product had a solids level of 49.2% by weight. The latex had a particle size of 154 nm. VI Preparation of Paint Compositions Nos.6-9 Copolymers No. 6 to 9 were formulated in paint compositions using Formulation No.2. For Paint Compositions No. 6-9, the pigments ground for each paint are the same. The dilutions varied by the amounts of binder, thickener and water. The level of thickener is varied to achieve a low slip final viscosity of 90-95 KU. The amount of water varies so that the final paint is 52% pigment volume concentration / 34% solids volume. Tamol 850 is a dispersant, available from Rohm and Haas. Triton CF-10 is a surfactant, available from Union Carbide Co. Colloid 643 is an antifoam, available from Rhone Poulenc. Ti -Puré R-902 is a titanium dioxide of rutile, available from DuPont de Nemours Co. Minex 4 is a silicate extender, available from Unimin Co. Eagle Zinc 417W is zinc oxide, available from Eagle Zinc Co. Natrosol 250 MR is solid grade ethyl cellulose hydroxide, available from Aqualon Co. Ropaque OP-96 is an emulsion polymer, available from Rhom and Haas Co. Texanol is a coalescent, available from Eastman Chemical Co. Acrysol SCT-275 is a thickener, available Rohm and Haas Co.

Formulation No. 2 Grams Water 150.0 Propylene Glycol 45.0 Tamol 850 (30%) 10.4 Potassium Tripolyphosphate (100%) 2.04 Triton CF-10 1.0 Colloid 643 2.0 Ti-Pure R-902 200.0 Minex 4 150.0 Eagle Zinc 417 25.0 Natrosol 250 MR ( 100%) 3.0 Water 60.0 The above ingredients were ground in a high speed disperser for 20 minutes. Binder see Table 3 Clothing OP-96 70.87 Texanol 17.72 Colloid 643 2.0 Acrysol SCT-275 see Table 3 Water see Table 3 Table 3 - Binder / Thickener / Water Levels Used in Formulation No. 2 We tested the efflorescence resistance of Paint Composition Nos. 6 to 9. The results are shown in Table 4. Paint Composition No.8, made from copolymer 8 and stabilized with oligomer B, provided improved efflorescence resistance on the Painting Composition Nos. 6, 7 and 9.

Table 4 Results of the efflorescence tests VII. Tile Test for Efflorescence A modification of the "Union Carbide Tile Test" was used to evaluate the efflorescence resistance of the test paints. In our test, an unglazed ceramic tile (American Olean Tile, Lansdale, PA) of 15 cm x 15 cm (6"x 6") was coated with test paint stained with phthalo blue in order to really show the white deposits. The bottom 2.5 cm (1") of the tile was left uncoated, the back of the tile had only one coat of paint, and the sides and front of the tile had two coats of paint. three days or seven days of drying, the tiles are placed in a grid so that only the lower part, the uncoated portion of the tile, is immersed in a 2% aqueous solution of sodium sulfate. the tile to simulate the efflorescence The tiles are left in the solution for 24 hours, then they are removed and left to dry The tiles are evaluated on a scale of 1 to 10, with 10 being the best resistance to efflorescence. are semi-quantitative, and will vary from operator to operator based on different judgments of the efflorescence severity, we find that for a given operator the results of the test for the same coating run multiple times did not vary more than +/- 1 unit. The results show that the composition of Paint No. 8, made with oligomer B, had superior efflorescence. Note that Paint Composition No. 9 with a lower level of AA (Copolymer 9), improved the efflorescence resistance in relation to Paint Composition Nos. 6 and 7, but not to the same extent as Paint Composition No 8. Therefore, it is not only the low incorporation of acid in the polymer particles which gives the excellent resistance to efflorescence. There is a unique effect for the B oligomer. VIII. Preparation of Copolymers No. 10-17 To a five liter agitator reactor containing 1180.8g of deionized water and 18.2g of Rhodapex CO-436 (Rhodia Corp., Cranberry New Jersey), which had been heated to 81 ° C. they added 114.8g of the emulsion or monomeric composition as described in Table 5. A solution of 3.3g of ammonium persulfate in 29g of deionized water and a solution of 0.4g of aqueous ammonia (29%) in 19g was then added. of deionized water. Eight minutes after the first addition the remaining monomeric emulsion or composition and a solution of 2g of ammonium persulfate in 220.2g of deionized water were added linearly and separately to the flask for 180 minutes while maintaining the temperature of the contents at 80.degree. -82 ° C. The monomeric emulsion was rinsed in the reactor with 40g of deionized water. A catalyst / activator pair was added after the monomer emulsion feed was completed. The polymer was neutrized with aqueous ammonia. The product was then diluted with deionized water to adjust the final solids of the latex. The latex solids, the particle size and the viscosity are shown in Table 5.

Copolymers No. 10 to 17 were formulated into paint compositions as shown in Table 6. A ground pigment was prepared for each paint in a high speed disk disperser. The ground pigment is shown as the first sets of components in Table 6. The grind was then diluted with the second set of components in Table 6. The final paints were 18 PVC, 34% volume solids. Tamol 681 is a dispersant, available from Rohm and Haas. Triton CF-10 is a surfactant, available from Union Carbide Co. Drew L-493 is an antifoam, available from Ashland Chemical Co., Dowanol DPM is a coalescent, trademark of Dow Chemical Co. Ti-Pure R-900 is a Rutile titanium dioxide, available from DuPont de Nemours Co. Texanol is a coalescer, available from Eastman Chemical Co. Acrysol RM-8 is a thickener, available from Rohm and Haas Co. Table 6 Paint Formulation Containing Copolymers a 17 Painting Composition # 10 11 12 13 14 15 16 17 Ingredients Water 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 Propylene Glycol 30.00 30.00 30.00 30.00 30.00 30.00 30.00 30.00 Dowanol DPM 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 Tamol 681 (35%) 8.80 8.80 8.80 8.80 8.80 8.80 8.80 8.80 Triton CF-10 2.20 2.20 2.20 2.20 2.20 2.20 2.20 2.20 Drew L-493 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ammonium hydroxide 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 28% Ti Pure R-900 205.50 205.50 205.50 205.50 205.50 205.50 205.50 205.51 Copolymer No. 10 621.30 Copolymer No. 11 632.00 Copolymer No. 12 630.00 Copolymer No. 13 623.00 Copolymer No. 14 614.30 Copolymer No. 15 618.60 Copolymer No. 16 618.90 Copolymer No. 17 620.00 Water 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 Ammonium hydroxide 10.00 5.00 5.00 8.30 10.60 18.20 17.40 24.40 (14%) Texanol 39.60 39.50 39.60 39.60 39.70 39.90 39.80 40.00 Water 43.00 37.50 39.80 45.00 50.80 39.50 40.20 32.30 Sodium Nitrite (15%) 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 Acrysol RM-8W 4.60 4.20 4.20 1.70 3.80 3.90 3.40 3.80 (17.5%) Total Weight? Or? aoo 1015.70 101 &10 1015.10 101 &70 1017.60 101720 1018.00 % of Weight of Solids 47.0 47.0 47.0 47.0 47.1 47.2 47.1 47.2 Volume% of 34.2 34.2 34.2 34.2 34.2 34.2 34.2 34.2 Solids% of Concentrations 18.0 18.0 18.0 18.0 18.0 18.0 18.0 18.0 of Pigment Volume IX. Corrosion Resistance / Salt Spray Test The corrosion resistance was tested by exposing the panels to a salt spray environment (5% sodium chloride mist). The panels were prepared by applying the paint on hot-rolled steel panels by sandblasting 10 cm x 30 cm (4"x 12") and drying for two weeks at 23.89 ° C (75 ° F) / 50% of relative humidity to produce a final dry film thickness of 5 x 10 ~ 3 cm (2 mil). The exposed metal was covered with tape (3M # 471 plastic tape) before exposure. A scratch mark is usually engraved on the lower half of the panel immediately before exposure. The panels are periodically removed to assess oxidation and blistering. The data in Table 7 show that the latexes stabilized by the Oligomer give significantly reduced oxidation and few blisters in the steel panels. Coatings 14 to 17, which comprise copolymers 14 to 17, demonstrate a superior balance of properties over compositions 10 to 13 based on conventional MAA, particularly with respect to corrosion resistance (corrosion resistance and blistering) . By extrapolation, it can be derived that the coatings formed from the compositions in which the oligomer content is 4.5% or more will not have the same superior balance of properties exhibited by the coatings where the oligomer content is less than 4.5% .

Table 7 Results of corrosion resistance tests, salt spray X. Preparation of high solids compositions Preparation of a High Bimodal Emulsion Polymer in Solids with "Oligomer A" A monomer mixture was prepared by combining 30Og of deionized water, 33.6g of sodium dodecyl benzene sulfonate (23% in water) , 995.9g of methyl methacrylate, 1548g of butyl acrylate and 124.5g of 29% Oligomer A aqueous solution. The monomer mixture is emulsified by mixing under standard conditions. 800g of deionized water was charged to a five liter flask and the contents were heated to 85 ° C. To the reaction flask was added 40.9 g of 45% solids, 100 nm of impregnated latex together with 10.32 g of ammonium persulfate dissolved in 19 g of deionized water. The monomer mixture was added to the reaction flask for 120 minutes while maintaining the temperature of the contents at about 85 ° C. Then 45% of the monomer mixture was added to the reaction flask, 62.5g of solids at 41.5%, 80nm of impregnated latex was added to the reaction flask. Any remaining monomer was reduced by the addition of aqueous ferrous sulfate, aqueous tertiary butyl hydroperoxide and sodium formaldehyde sulfoxylate. The polymer was neutralized to a pH of about 7.0 with ammonia. The reaction mixture was then cooled to room temperature. The resulting latex had a solids content of 63%, a viscosity of 160 cps and two modes indicating a mode having an average particle size of 120 nm and the other mode having an average particle size of 240 nm. Comparative Example: Preparation of a Bimodal High Emulsion Polymer in Solids with Acrylic Acid An emulsion polymer prepared as above with an equal weight of acrylic acid substituted by "Oligomer A", produced a 63% solids latex with a viscosity of 270 cps and two modes indicating a mode having an average particle size of 119 nm and the other mode having an average particle size of 230 nm. Preparation of a High Multimodal Emulsion Polymer in Solids with "Oligomer A" A monomer mixture was prepared by combining 201 g of deionized water, 29.5 g of sodium dodecyl benzene sulfonate (23% in water), 874.2 g of methyl methacrylate, 1358.8 g of butyl acrylate and 109.3 g of a 29% aqueous solution of Oligomer A. The monomer mixture was emulsified by mixing under standard conditions. 459g of deionized water was charged to a five liter flask and the contents were heated to 85 ° C. To the reaction flask was added 19.3g of 45% solids, 100 nm of impregnated latex together with 4.81g of ammonium persulfate dissolved in 17g of deionized water. The monomer mixture was added to the reaction flask for 120 minutes while maintaining the temperature of the contents at about 85 ° C. After 25% of the monomer mixture was added to the reaction flask, a solution of 1.92g of ammonium persulfate in 50g of deionized water was added over a period of 120 minutes. Then 45% of the monomer mixture was added to the reaction flask, 35.lg of solids at 41.5%, 80 nm of impregnated latex were added to the reaction flask. After 75% of the monomer mixture was added to the reaction flask, 98.5 g of sodium dodecylbenzene sulfonate (23% in water) were added to the reaction flask followed by 17.5 g of deionized water. After the additions were completed the contents of the flask were maintained at 85 ° C for an additional hour. The reaction mixture was then cooled to room temperature. The resulting viscous latex had a solids content of 70%.

Claims (15)

1. CLAIMS 1. An aqueous composition comprising, dispersed or dissolved therein, a copolymer formed by the polymerization of a monomer mixture consisting of: a) from 0.05 to less than 4.5% by weight of one or more terminally unsaturated oligomers of the formula: coo x wherein N is the residue of an ethylenically unsaturated monomer of the formula: -CH2-CZ- I COOY where M is the residue of an ethylenically unsaturated monomer other than N; wherein the N and M residues are randomly ordered in the oligomer; where m is the total number of residues M in the oligomer and is in the range of 0 to 75; where n is the total number of residues N in the oligomer and is in the range of 3 to 150; where n is equal to or greater than m and the sum of n and m is in the range of 3 to 150; wherein X and each Y are independently selected from the group consisting of H, NH 4, alkali metals and alkaline earth metals; and wherein each Z is independently selected from the group consisting of H and CH3; b) greater than 85.5 to 99.95% by weight of at least one monomer selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids which contain from 1 to 20 carbons, vinyl aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and c) 0 or up to 10% by weight of one or more copolymerizable monomers.
2. 2. An aqueous composition as claimed in claim 2, wherein X, Y and Z are each H.
3. 3. An aqueous composition as claimed in claim 1, wherein M is a residue of one or more ethylenically active monomers. unsaturates selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate, styrene, isoprene, butadiene, vinyl acetate, acrylamide, acrylonitrile, allyl methacrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate.
4. 4. An aqueous composition as claimed in claim 1, wherein the monomers b) are selected from the group consisting of methyl (meta) acrylate, ethyl (meth) acrylate, butyl (meta) acrylate, 2-ethylexyl (meta) acrylate, decyl (meta) acrylate, lauryl (metha) acrylate, isobornyl (metha) acrylate, isodecyl (metha) acrylate, oleyl (metha) acrylate, palmityl (metha) acrylate, sterile (metha) acrylate, styrene, butadiene, vinyl acetate , vinyl chloride, vinylidene chloride, acrylonitrile, meta acrylonitrile, acrylamide and glycidyl methacrylate.
5. 5. An aqueous composition as claimed in claim 1, wherein the monomers c) are selected from the group consisting of hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mono-methyl itaconate, mono-methyl fumarate, mono-butyl fumarate, maleic anhydride, phospho-ethyl methacrylate, glycidyl (meta) acrylates, substituted acrylamides, diacetone acrylamide, glycidyl (meta) acrylates, glycidyl methacrylate, acetoacetoxy ethyl methacrylate, acrolein , metaacrolein, dicyclopentadienyl methacrylate, dimethyl meta-isopropenyl benzyl isocyanate, isocyanate ethyl methacrylate, methyl cellulose, hydroxyethyl cellulose, ethylene, propylene, N-vinyl pyrrolidone, N, N'-dimethylamino (meta) acrylate and polymerizable surfactants.
6. 6. An aqueous composition as claimed in claim 1, wherein the copolymer has an average molecular weight of above 1,000,000, as measured by gel permeation chromatography.
7. 7. An aqueous composition as claimed in claim 1, wherein the copolymer has a glass transition temperature (Tg) in the range of from -25 to 120 ° C as measured by Differential Scanning Calorimetry.
8. 8. An aqueous composition as claimed in claim 1, wherein the monomer mixture which was polymerized to form the copolymer preferably comprises from 0.5% to 4% by weight of the oligomer a) terminally unsaturated.
9. 9. An aqueous composition as claimed in claim 1, wherein the copolymer is in the form of a latex dispersion wherein the particles of the latex dispersion have an average diameter no greater than 250 nm.
10. 10. An aqueous composition as claimed in claim 1, wherein the composition further comprises inorganic particulate material.
11. 11. An aqueous composition as claimed in claim 1, wherein the composition is in the form of an aqueous dispersion of polymer particles having a multi-modal distribution of particle size, wherein at least one mode of the The multi-modal particle size distribution is attributable to a dispersion of polymer particles comprising a copolymer formed by the emulsion polymerization of a monomer mixture comprising: a) from 0.05 to less than 4.5% by weight of one or more oligomers terminally unsaturated formula: CO O X wherein N is the residue of an ethylenically unsaturated monomer of the formula: -CH2-CZ-COOY wherein M is the residue of an ethylenically unsaturated monomer other than N; wherein the N and M residues are randomly ordered in the oligomer; where m is the total number of residues M in the oligomer and is in the range of 0 to 75; where n is the total number of residues N in the oligomer and is in the range of 3 to 150; where n is equal to or greater than m and the sum of n and m is in the range of 3 to 150; wherein X and each Y are independently selected from the group consisting of H, NH 4, alkali metals and alkaline earth metals; and wherein each Z is independently selected from the group consisting of H and CH3; b) greater than 85.5 to 99.95% by weight of one or more monomers selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids which contain from 1 to 20 carbons, vinyl aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and c) 0 or up to 10% by weight of one or more copolymerizable monomers.
12. 12. An aqueous composition as claimed in claim 11, comprising from 40 to 75% by weight of polymer solids.
13. An aqueous composition as claimed in claim 11, wherein at least one mode of the multi-modal particle size distribution is attributed to a dispersion of polymer particles having an average particle diameter of from 40 to 100. nm.
14. 14. An aqueous composition as claimed in claim 13, wherein a larger portion of the polymer particles within the at least one mode having an average particle diameter from 40 to 100 nm are copolymer particles.
15. 15. A method for improving the performance of a coating, wherein the method comprises I) applying an aqueous coating composition to a substrate and II) drying the aqueous coating composition to form the coating characterized in that the aqueous coating composition comprises an aqueous composition as claimed in claim 1.