AU2005229399A1 - Coating masses made from low-emission binding agents - Google Patents

Abstract

The aim of the invention is low-odour, solvent-free workable binder polymers, method for production thereof, coating masses made from said binder polymers and the use thereof.

Description

IN THE MATTER OF an Australian Application corresponding to PCT Application PCT/EP2005/003219 RWS Group Ltd, of Europa House, Marsham Way, Gerrards Cross, Buckinghamshire, England, hereby solemnly and sincerely declares that, to the best of its knowledge and belief, the following document, prepared by one of its translators competent in the art and conversant with the English and German languages, is a true and correct translation of the PCT Application filed under No. PCT/EP2005/003219. Date: 1 August 2006 C. E. SITCH Acting Managing Director For and on behalf of RWS Group Ltd 1 Coating masses made from low-emission binding agents Description 5 The present invention relates to low-odor, solventlessly processable binder polymers, to a process for preparing them, to coating materials based on these binder polymers, and to the use thereof as pigmented formulations. Pigmented formulations are employed widely in the form of emulsion paints, synthetic 10 resin-bound plasters (dispersion plasters), sealants or filling compositions for purposes of architectural protection or decoration. Pigmented formulations generally comprise as their binder a film-forming polymer, at least one inorganic pigment and, if appropriate, one or more inorganic fillers, and other customary fillers. The quality of the coatings formed from pigmented formulations depends critically on the ability of the film-forming polymer to 15 effect binding of the non-film-forming constituents, the pigments and inorganic fillers. A low pigment binding capacity leads to poor mechanical stability in the coating, which is manifested for example in a low wet abrasion resistance. The desire, however, is for high wet abrasion resistance, especially in washable emulsion paints. 20 The pigment binding capacity of the binder plays a particularly important part in formulations containing a higher proportion of inorganic pigments and fillers. Formulations of this kind are generally characterized by a pigment volume concentration (PVC) >40%. The pigment volume concentration is usually defined as the percentage 25 ratio of the overall volume of solid inorganic constituents (pigments + fillers) to the total volume of the solid inorganic constituents and the volume of the polymer particles of the aqueous binder polymer dispersion (see Ullmanns Enzyklop~die der technischen Chemie, 4th Edition, Volume 15, page 668). 30 In the case of exterior applications in particular, the coatings ought to be stable to environmental influences, such as sunlight, moisture and fluctuations in temperature. They ought to make the coated areas resistant to absorption of moisture, such as rain, but to be able to re-emit moisture that has been absorbed readily, in the form of water vapor, while not themselves being soiled or grayed. The coating material must further 35 adhere well to different substrates, and must be compatible with silicone compounds and highly alkaline silicate solutions, this compatibility likewise being dependent on the type of binder chosen. Another property dependent on the binder polymer is the blocking resistance of the coatings, particularly when they are brush-applied compositions. 40 In the context of use as binders in synthetic-resin-bound plasters or filling compositions, it is necessary that the coatings obtained, in either a thin or a thick film, are flawless, drying with no cracks. These coatings require high bond strengths, particularly if they form part of an exterior insulation and finishing system. They should exhibit little water absorption 2 and should be stable to freeze/thaw cycles, i.e., should not flake from the substrate or detach. It is additionally very advantageous if they contribute to good, i.e., low, fire behavior. 5 To reduce the environmental burden and from the standpoint of occupational hygiene it is desirable for coating materials, especially those used in enclosed areas, such as emulsion paints, polymer dispersion plasters or tile adhesives, not to give off nonaqueous, volatile, organic or inorganic constituents to their surroundings. One of the ways in which this can be achieved is to use aqueous polymer dispersions as binders for 10 these coating materials. Aqueous polymer dispersions of suitable composition, when the dispersant - preferably water - is evaporated, have the ability below their minimum film-forming temperature (MFFT) to form transparent polymer films, and this is why aqueous polymer dispersions 15 are frequently employed as binders, such as for paints or materials for coating walls (dispersion resin plasters). Conventional binders based on aqueous polymer dispersions or their end formulations, however, generally still comprise small amounts of inorganic solvents. These are 20 necessary in order to reduce the minimum film-forming temperature (MFFT) of the binder polymers and so to ensure that the coating materials can be processed even at low temperatures. The MFFT of the polymeric binders can also be lowered by "internal plasticization", i.e., by a lowering of the glass transition temperature (Tg) of the binder polymer (see Ullmann's Encyclopedia of Industrial Chemistry, VCH Weinheim, 1992, Ed. 25 5, Vol. A21, page 169). If the MFFT of the polymeric binder is too low, however, there is a danger that the coating materials will have a poor pigment binding capacity and will lack adequate mechanical strength, and, moreover, will be too tacky and will easily soil (see H. Rinno, Farbe&Lack, 1993 series, Volume 99, pages 697 to 704). If the MFFT is too high or has not been sufficiently lowered, on the other hand, the polymeric binder will not 30 achieve sufficient filming (pigment binding), which is manifested in inadequate mechanical strength (scrub resistance, for example) or increased abrasion and/or flaking. For reasons of cost it is advantageous for the polymeric binder to have the capacity to bind large amounts of pigments and fillers. Interior emulsion paints, for example, have 35 pigment volume concentrations in the range from 50 to 80%. If the PVC tolerated by the polymeric binder is exceeded then the coating material lacks adequate wet abrasion resistance. According to H. Warson in 'Synthetic Resin Emulsions', E. Benn Ltd., London, 1972, pages 776ff, polymeric binders have a high pigment binding power if they comprise from 1 to 4% by weight of copolymerized, carboxyl-containing monomers. In the case of 40 high-grade polymeric binders the amount of these monomers, indeed, is between 2.5 and 7% by weight. Alternatively, if the acid content is too high, there is a danger that the binder polymer will become too soluble in water and hence that there will be a reduction 3 in the wet abrasion resistance of the coating materials, they will give off excessive moisture to the underlying coats, and a good colonization medium for algae, fungi and bacteria will be formed. 5 EP-A-652 269 describes an acrylamide-containing binder for low-emission coating materials, comprising a coarse latex having particle sizes in the range from 100 to 500 nm and a fine latex having particle sizes in the range from 5 to 40 nm. Besides the principal monomers of the coarse latex, which are selected from styrene, butadiene, vinyl nitriles and acrylic esters, the latex comprises 0.1 to 5% by weight of crosslinking 10 monomers, 0 to 20% by weight of ethylenically unsaturated carboxylic acids and 0 to 40% by weight of further monomers in copolymerized form. The use of binders comprising two polymer dispersions prepared independently of one another, and of expensive monomers with a crosslinking action, is too complicated for inexpensive coating materials. Furthermore, the emulsion paints described do not yield paint films 15 having satisfactory abrasion performances, either when a binder comprising coarse and fine polymer dispersions is used or when the coarse polymer dispersion is used on its own. EP-A-1 134 240 also discloses binders, characterized by an acid fraction of 0 to 4% by 20 weight and 0.001 to 0.1% by weight, based on total monomer amount, of crosslinking monomers. Binders of this kind are suitable, among other things, as binders for emulsion paints and dispersion plasters. The binders possess an MFFT of less than 1 0*C. Crosslinking monomers are relatively expensive, so that even a small amount raises the production costs of the binder to a considerable degree. 25 WO-A-94/21699 describes binders for solvent-free emulsion paints having improved washability, composed of 60 to 100% by weight of acrylic or methacrylic esters, 0 to 40% by weight of vinylaromatic monomers, 0 to 5% by weight of a,p-unsaturated monocarboxylic or polycarboxylic acids and 0 to 3% by weight of at least one cap 30 unsaturated amide. The examples describe polymer dispersions containing at least 2.5% by weight of acrylic acid in copolymerized form. The emulsion paints described in examples 6 to 9, comprising these polymers as binders, likewise lack satisfactory abrasion performances. 35 EP-A-0 810 274 describes low-emission binders for coating materials with improved abrasion resistance. The polymers used as binders comprise s1% by weight of a carboxylic acid-containing comonomer and have a Tg s10*C. DE-A-1 02 06 994 teaches emulsion polymers for use as binders for interior silicate 40 emulsion paints, composed of an acrylic ester, styrene, a monocarboxylic or dicarboxylic acid and/or an acrylamide having a viscosity of 40 to 400 mPas. In all of the working examples use is made of emulsifiers based on nonylphenol. Alkylphenol ethoxylates 4 (APEs), such as ethoxylated nonylphenol, are needed as emulsifiers if the desire is for a high affinity for hydrophobic pigment surfaces (see Farbe&Lack, 2002 series, Volume 108, pages 58 to 63). 5 DE-A-34 23 765 discloses low-acid polymers for binders in paper coatings. Thus example 3 shows a copolymer of 39.5% by weight 2-ethylhexyl acrylate, 39.5% by weight n-butyl acrylate, 20% by weight styrene and 1% by weight acrylic acid, which is prepared in the presence of 17 parts of a 30% strength by weight formaldehyde solution and leads to the formation of 10 parts of coagulum. If formaldehyde solution is omitted, 300 parts of 10 coagulum are formed (comparative example 3). Low-acid polymers therefore have stability problems, which are overcome by means of formaldehyde solution. For applications with brush-applied paints, particularly in the interior sector, the use of formaldehyde is unacceptable. 15 DE-A-198 58 851 describes aqueous copolymer dispersions, especially in elastic coatings. The polymers are obtained by emulsion polymerization of a) 40 to 99.9% by weight of at least one ester of an unsaturated carboxylic acid and up to 40% by weight of a vinylaromatic, 20 b) 0.05-10% by weight of an unsaturated monobasic or dibasic acid and 0 to 10% by weight of an unsaturated carboxamide, c) 0.05 to 10% by weight of an unsaturated crosslinking monomer and d) 0 to 30% by weight of another copolymerizable monomer. 25 The polymers have a solids content of 20-65% and a glass transition temperature of -50 to +35*C. Their use in elastic coatings necessitates the additional use of crosslinking monomers, which has the effect of making the resultant synthetic resin relatively expensive. The dispersions may further comprise carboxamides, and also polyacrylamide protective colloids and mercaptans, can be neutralized with ammonia, and comprise 30 solvents and film formers. All of these factors have a deleterious effect on the odor of the products. The possible use of Rongalit as well further releases a significant fraction of formaldehyde through elimination. All in all, such polymers are found to be not very suitable for low-emission binders in coating materials. 35 EP-A-0 331 011 describes the production of dispersions free of protective colloid and/or low in emulsifier, which are composed of one or more monomers from the group of acrylic or methacrylic esters and 0.1 to 2% by weight of a water-soluble, conjugated sulfonic acid comprising 4 to 26 carbon atoms, and/or its salts. The products are also suitable as binders for paints. They are prepared in the presence of formaldehyde donor 40 compounds or in the presence of alkylphenol-containing emulsifiers.

5 An object of the present invention, in view of the above state of the art, was to provide coating materials based on improved low-odor, solventlessly processable binders of high pigment binding capacity, which are easy and uncomplicated to prepare and whose preparation does not use ecologically objectionable components, but which lead to stable 5 paints with good hiding power and (wet) abrasion resistance. These paints are to be suitable for preparing interior paints and also for preparing exterior paints and dispersion plasters. By ecologically objectionable substances are meant components which are counted 10 among allergens or substances objectionable from a health standpoint, such as, for example, acrylamide, formaldehyde, acetaldehyde, evaporating solvents, volatile film forming auxiliaries, plasticizers, residual quantities of volatile monomers, heavy metals and compounds which may possibly exert a hormonal effect. The latter are taken at present to include alkylphenol ethoxylates. Where such components have a low boiling 15 point they are given off with particular readiness to the surrounding area. The binders and the coating materials ought in particular to exhibit high silicate compatibility and to be stable on storage. 20 The object has been achieved through the provision of binders comprising at least one addition polymer obtained by free-radically initiated aqueous emulsion polymerization of a mixture of ethylenically unsaturated monomers composed of 20 to 60% by weight of 2-ethylhexyl acrylate (monomer A) 25 0 to 40% by weight of one or more monomers each of whose homopolymer has a glass transition temperature <10*C (monomers B), 30 to 70% by weight of at least one monomer whose homopolymer has a glass transition temperature >50 0 C (monomers C), 0.1 to 5% by weight of at least one monomer containing acid groups (monomers D), 30 and 0 to 5% by weight of at least one further monomer having at least one hydroxyl, keto and/or silane group in the side chain (monomers E), based in each case on the total amount of ethylenically unsaturated monomers used for 35 the polymerization, using alkylphenol ether-free emulsifiers, the polymer having a minimum film-forming temperature of below 15*C and comprising less than 0.01% by weight of compounds having a boiling point below 50 0 C. The binders comprise preferably less than 0.005% by weight, more preferably less than 40 0.001% by weight, having a boiling point below 50*C, more preferably below 35*C.

6 The present invention further provides a process for preparing aqueous polymer dispersions of the invention, and also provides for their use for coating, adhesive bonding, sealing, spreading, spraying, squirting or impregnating, preference being given to their use as binders for paints. 5 The preparation of the binders does not involve use of any compounds having a boiling point below 500C, preferably below 35 0 C, or of any compounds able through hydrolysis to give off such compounds. 10 Examples of compounds which through hydrolysis can give off compounds having a low boiling point are acrylamide and methacrylamide and their homopolymers and copolymers (release of ammonia), Rongalit (release of formaldehyde), and vinyl acetate and its homopolymers and copolymers (release of acetaldehyde and acetic acid). 15 The polymers of the invention are composed of: Monomer A: 20 to 60%, preferably 30 to 55%, more preferably 40 to 50% by weight of 2-ethylhexyl 20 acrylate. Monomer B: 0 to 40%, preferably 3 to 35%, more preferably 5 to 30% by weight, the homopolymer 25 thereof having a glass transition temperature <1O*C. The glass transition temperature, Tg, is the limit value of this parameter toward which it tends, according to G. Kanig (Kolloid-Zeitschrift & Zeitschrift fOr Polymere, Volume 190, page 1, equation 1), with increasing molecular weight. The Tg is determined by the DSC 30 method (Differential Scanning Calorimetry, 20 K/min, midpoint measurement, DIN 53 765). The Tg values for the homopolymers of the majority of monomers are known and are listed for example in Ullmann's Encyclopedia of Industrial Chemistry, VCH Weinheim, 1992, 5th ed., Vol. A21, page 169ff.; additional sources of glass transition temperatures of homopolymers include for example J. Brandrup, E.H. Immergut, Polymer 35 Handbook, 15th ed., J. Wiley, New York 1996, 2nd ed., J.Wiley, New York 1975, and 3rd ed., J. Wiley, New York 1989. To obtain the desired glass transition temperature, Tg, of the binder polymer by selecting suitable types and amounts of monomers A to E the formula of Fox (T.G. Fox, Bull. Amer. Phys. Soc. (Ser. II) 1956 series, Volume 1, pages 123ff.) is useful, according to which it is the case in good approximation for the glass 40 transition temperature of copolymers that: 1/Tg = x 1 /Tg 1 + X 2 /Tg 2 + ...... + x/Tgn 7 in which x 1 , x 2 , -- xn are the mass fractions of the monomers and Tg 1 , Tg 2 , ..., Tg, the glass transition temperatures of the homopolymers composed in each case of one of the monomers 1, 2, ..., n, in kelvins. 5 Suitable monomers B are acrylic esters of linear or branched C1 to C1O alkanols, examples being n-propyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n-nonyl or n-decyl, or cyclic C5 to C10 cycloalkyl groups, such as the cyclopentyl or cyclohexyl radical. It is also possible to use n-hexyl methacrylate, butadiene and/or vinyl ethers of C3 to CIo alkanols, 10 branched and unbranched C3 to C1O olefins. Particularly preferred monomers B used are n-butyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate and/or butadiene or mixtures thereof. 15 Monomers C: 30 to 70%, preferably 40 to 60%, more preferably 45 to 55% by weight of at least one monomer whose homopolymer has a glass transition temperature >50"C. 20 Suitable monomers C are vinylaromatic monomers, C1 to C4 alkyl methacrylates and/or a,f-unsaturated carbonitriles whose homopolymers have a glass transition temperature >50*C, preferably >800C. By vinylaromatic monomers are meant in particular styrene or a-methylstyrene and also the ring-substituted derivatives thereof. Preferred monomers C are styrene, methyl methacrylate, tert-butyl methacrylate, tert-butyl acrylate, lauryl 25 acrylate and stearyl acrylate. Styrene is particularly preferred. Monomers D: 0.1 to 5%, preferably 1 to 4%, more preferably 1.5 to 3% by weight of at least one 30 monomer containing acid groups. The monomers D are ethylenically unsaturated monomers which are able to form anionic groups. These groups are preferably carboxylate or sulfonate groups, with particular preference carboxylate groups. Particularly preferred monomers D are monoethylenically 35 unsaturated C3 to C8 monocarboxylic or dicarboxylic acids or their anhydrides, such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid and itaconic anhydride, and acrylamidoglycolic acid. Ethylenically unsaturated alkyl- or arylsulfonic acids as well, such as vinylsulfonic acid, methallylsulfonic acid, vinylbenzenesulfonic acid, acrylamidoethanesulfonic acid, 40 acrylamido-2-methylpropanesulfonic acid (AMPS), 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate and 3-sulfopropyl methacrylate, are suitable, preferably in a mixture with carboxylic acids. The monomers D containing acid groups 8 may also be used in fully or partly neutralized form. Particular preference is given to acrylic acid, methacrylic acid, itaconic acid, maleic acid and AMPS or a mixture thereof. The special preference is given to acrylic acid and methacrylic acid, especially acrylic acid. 5 Monomers E: 0 to 5% by weight of at least one further monomer having at least one hydroxyl, keto and/or silane group in the sidechain. 10 The monomers E are monomers which exhibit a heightened solubility in water but do not possess acidic groups, or which endow the polymer with additional functional groups for adhesion to the other components present in the coating compositions. They generally raise the pigment binding capacity of the binders. They are present in a fraction of 0 to 15 5% by weight, preferably below 3% by weight. Particularly suitable are hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, polyethylene oxide (meth)acylate, acetoacetoxymethacrylate and polyvinyl alcohol. Their water solubility is usually above 100 g/1 000 cm 3 water at 25 0 C. 20 Mention may further be made of glycidyl (meth)acrylate, acetoacetoxymethacrylate, ureidoethyl methacrylate, acrylamidoethylethyleneurea, and N,N'-bis(acrylamido ethyl)ethyleneurea. The pigment binding capacity of the polymer dispersions may be increased further, for 25 example, by polymerized incorporation of silanes containing olefinic double bonds, examples being vinylsilanes or methacryloyloxyalkylsilanes (see above, and also EP-A-0 327 006, EP-A-0 327 376 or EP-A-0 612 771). Additionally it is possible to introduce silane groups according to EP-A-0 640 629 by polymerization in the presence of epoxysilanes, glycidyloxypropyltrimethoxysilane for example, or according to 30 EP-A-0 327 376 by polymerization in the presence of mercaptoalkyltrisalkoxysilane, into the binder polymer. Compounds possessing N-methylol groups may likewise be used as monomers E: preferably, however, they are not used, since they give off formaldehyde. Examples of 35 such compounds are, in particular, N-methylolacrylamide, N-methylolacrylamide or a mixture thereof. The polymer formed from the monomers A to E comprises sufficient of monomer A and B to give it an MFFT of below 15*C, of below 12*C, more preferably of below 10C. A low 40 MFFT in the polymers guarantees that they will form films effectively, even in formulations free from solvent and coalescer, and so leads to good and high pigment compatibility. Too low an MFFT leads-to tacky coating materials which as a result are 9 readily soiled. A higher MFFT, a higher molecular weight of the binder polymers and a greater average particle size of the binder polymers has a corresponding impairing effect on the pigment binding capacity. In order to arrive at optimum pigment binding capacity the state of the art teaches the use of stage polymers, or the additional use of 5 crosslinking monomers to raise the average molecular weight, or the copolymerization of acrylamide in order to produce a higher gel fraction. Acrylamides and the ammonia produced from it to a certain extent as a result of hydrolysis are now the subject of health concerns, since, on drying, the substances are given off to the surrounding area. Hydrolysis reactions of this kind take place in particular in alkaline formulations or in the 10 case of coatings applied to heavily alkaline substrates. In accordance with the invention it has been found that in the case of copolymers of 2-ethylhexyl acrylate and styrene there is already sufficient formation of highly crosslinked and branched polymer structures that the additional use of crosslinking 15 monomers or strongly gel-forming monomers can be omitted. It is supposed that the introduction of the branched sidechain of the 2-ethylhexyl acrylate monomer (monomer A) supports the more intensive grafting of the polymer main chain and sidechain onto the tertiary CH groups. The extremely hydrophobic polymer building blocks additionally lead to an advantageous, lower water sensitivity of the coatings and hence also to better wet 20 scrub resistance of the coating materials. The at least one polymer used in the coating materials of the invention is carried out advantageously by free-radically initiated aqueous emulsion polymerization of the stated monomers A to E in the presence of 0.1 to 1.0%, preferably 0.1 to 0.5% and particularly 25 0.2 to 0.3% by weight, based in each case on the total amount of monomers A to E, of at least one free-radical polymerization initiator. Suitable free-radical polymerization initiators include all those capable of triggering a free-radical aqueous emulsion polymerization. These may in principle be not only peroxides, in the presence if appropriate of reducing agents, but also azo compounds. Peroxides which can be used 30 include in principle inorganic peroxides, such as hydrogen peroxide, or peroxodisulfates, such as the alkali metal salts of peroxodisulfuric acid, such as their sodium or potassium salt, for example, or organic peroxides, such as alkyl hydroperoxides, examples being tert-butyl, p-menthyl or cumyl hydroperoxide, and also dialkyl or diaryl peroxides, such as di-tert-butyl or dicumyl peroxide. Ammonium persulfate, too, is suitable in principle but 35 already introduces small but detectable amounts of ammonia into the system. Suitable oxidizing agents for redox initiator systems are essentially the abovementioned peroxides. As corresponding reducing agents it is possible to use sulfur compounds with a low oxidation state, such as alkali metal sulfites, e.g., potassium and/or sodium sulfite, alkali metal hydrogensulfites, e.g., potassium and/or sodium hydrogensulfite, alkali metal 40 metabisulfites, e.g., potassium and/or sodium metabisulfite, and alkali metal hydrogen sulfides, such as potassium and/or sodium hydrogen sulfide, and also oxidizable enediols, suc as dihydroxymaleic acid, benzoin and/or ascorbic acid or isoascorbic acid, 10 and also reducing saccharides, such as sorbose, glucose, fructose and/or dihydroxyacetone. Formaldehyde-sulfoxylates, such as potassium and/or sodium formaldehyde-sulfoxylate, can also be used but are less preferred on account of their release of formaldehyde. If appropriate, salts of polyvalent metals, such as iron(Il) sulfate, 5 iron(II) ammonium sulfate and iron(II) phosphate, are used as catalytically active components in small amounts. Particular preference is given to sodium peroxodisulfate and hydrogen peroxide, in combination if appropriate. It is preferred to use below 0.6% by weight, very preferably below 0.5% by weight, of sodium peroxodisulfate. 10 For preparing the at least one polymer it is preferred to use, in addition to the surface active substances usual for an aqueous emulsion polymerization, at least one nonionic or anionic emulsifier in amounts of preferably 0.3 to 10%, in particular between 0.7 to 7% and very preferably 0.9 to 4% by weight, based in each case on the total monomer amount. Preference is given to using a combination of an anionic and nonionic emulsifier 15 or of two anionic emulsifiers, in particular in a weight ratio of 1:5 to 5:1. Mixtures of emulsifiers are preferably used since in that case advantages are produced with respect to foam propensity. With advantage a low electrolyte load is formulated. Nonionic emulsifiers which can be used are aliphatic ethoxylates of long-chain alcohols 20 and also polyethylene oxide/polypropylene oxide block copolymers. Preference is given to using ethoxylates of long-chain alkanols, particularly of fatty alcohols or oxo alcohols. Suitable alcohols are C8 to C36 alcohols, preferably C10 to C22 alcohols, more preferably C12 to C18 alcohols. The average degree of ethoxylation is typically from 3 to 50, preferably from 3 to 30. 25 Further customary emulsifiers are preferably anionic in nature. They include neutralized C8 to C12 alkyl sulfates, sulfuric monoesters of ethoxylated linear or branched C12 to C18 alkanols with an average degree of ethoxylation of 2 to 50, C12 to C18 alkylsulfonic acids and C8 to C18 alkylarylsulfonic acids or sulfosuccinic esters, including monoesters, or 30 sulfosuccinic ester amides. Neutralized primary or secondary alkyl or ethoxylated alkyl phosphates or phosphonates having an average degree of ethoxylation of from 2 to 50 and a C12 to C18 alkyl radical can also be used. The emulsifiers are preferably in the form of sodium or potassium salts or of substituted ammonium salts, such as the triethanolamine, diethanolamine or monoethanolamine salt. The simple ammonium salts, 35 obtained by neutralization using ammonia solution, are of course equally suitable, but are not used with preference owing to the potential emission of ammonia. Further suitable emulsifiers can be found in Houben-Weyl, Methoden der organischen Chemie, Volume XIV/1, Makromolekulare Stoffe [Macromolecular compounds], Georg-Thieme Verlag, Stuttgart, 1961, pages 192 to 208. Preferred anionic surface-active substances are the 40 sodium salts of the alkyl sulfates.

11 Further anionic emulsifiers which have additionally proven appropriate are compounds of the general formula I R1 R 2 0

SO

3 A 03B 5 in which R 1 and R 2 , independently of one another, are hydrogen or C 1 to C24 alkyl but are not simultaneously hydrogen or C 1 to C3 alkyl, and A and B can be alkali metal ions. R 1 and R 2 in the general formula I are preferably linear or branched C6 to C18 alkyl radicals, particularly C6, C1 2 and C 16 alkyl radicals, or a hydrogen atom. A and B are preferably sodium, ammonium or potassium, sodium being particularly preferred. Particular 10 advantage attaches to compounds I in which A and B are sodium, R 1 is a branched C12 alkyl radical and R 2 is a hydrogen atom or R 1 . Generally speaking, use is made of technical-grade mixtures which contain a 50 to 90% by weight fraction of the monoalkylated product, such as Dowfax@ 2A1 (trademark of the Dow Chemical Company), for example. Compounds I are general knowledge, from US-4,269,749 and 15 EP-A-0 952 161, for example, and are available commercially, being used preferably in combination with another anionic emulsifier. Furthermore it is possible to use suitable protective colloids, alone or in combination with above emulsifiers, such as polyvinyl alcohols, cellulose derivatives or vinylpyrrolidone 20 copolymers. A detailed description of further suitable protective colloids can be found in Houben-Weyl, Methoden der Organischen Chemie, Vol. 14/1, Makromolekulare Stoffe [Macromolecular compounds], Georg-Thieme-Verlag, Stuttgart, 1961, pages 411 to 420. The total amount of protective colloids is usually a multiple, i.e., up to 10 times, of the amount by weight of emulsifiers. 25 The molecular weight of the polymers formed from the monomers A to E can in principle be adjusted by adding small amounts, less than 2% by weight, based on the total amount of monomers to be polymerized, of one or more molecular weight regulator substances, examples being organic thio compounds, preferably thioalkylsilanes, or allyl alcohols. 30 Preference is given, however, to polymers prepared in the absence of such compounds. Substances which have proven appropriate for photochemical postcrosslinking curing include acetophenone, benzophenone and derivatives thereof. These substances lead, after application and drying, to post-curing reactions in the paint on the masonry on 35 exposure to light, and this has a beneficial effect in particular on the soiling behavior of the paint. Particular preference is given to using benzophenone and/or a derivative thereof. Mixtures of this kind are known for example from EP-A-0 209 831. Copolymerizable derivatives as well are known in the prior art. These components are 12 normally added in amounts of 0.03 to 2% by weight, based on total polymer, to the dispersion while it is still hot. Preparation of emulsion polymers: 5 The binders of the invention are prepared by the process of free-radical aqueous emulsion polymerization in the presence of the abovementioned dispersants and free radical polymerization initiators. In this process the mixture of the monomers is converted with the aid of emulsifiers and water into an emulsion, which is added to the actual 10 polymerization vessel. The ratio of the water phase to the total amount of the monomers is chosen in accordance with the desired solids content of the emulsion polymer to be prepared. It is preferred to aim for solids contents of 30 to 65% by weight, very preferably 40 to 55% by weight, in order to allow the formulation of sufficiently concentrated coating materials. 15 The emulsion polymerization can be carried out both continuously and batchwise, but preferably by a semicontinuous process. In such a process a portion of the monomers to be polymerized is included in the initial charge to the reaction vessel and the remainder is added to the polymerization batch continuously, linearly, in stages or as a gradient. 20 Preference is given to a semicontinuous feed process in which up to 20% by weight of the monomers are included in the initial charge to the reaction vessel at elevated temperature, together with a portion of the polymerization initiator and of the emulsifier, and the remainder of the monomers, of the initiator and of the emulsifier is added to the polymerization batch. From a practical viewpoint, such as for reasons of line cleaning, for 25 example, it may also be the case, after the emulsion has been metered in completely, that small amounts, i.e., generally less than 5% by weight, of the monomers are added to the reaction vessel, individually or as a mixture, in an unemulsified form. The metering time required for the monomer emulsion depends essentially on the 30 selected ratio of monomer to water and on the cooling performance made available for the polymerization reactor. Preference is given to a feed process with very short feed times: in other words, the monomers, preferably in the form of an aqueous emulsion, are supplied to the reaction mixture over the course of 1 to 6 hours, preferably between 2 and 5 hours. 35 Besides the seed-free preparation mode it is possible, in order to adjust the polymer particle size, for the emulsion polymerization to take place in accordance with the seed latex process or in the presence of a seed latex prepared in situ. Processes to this effect are known and can be found in the prior art (see for example EP-B-0 040 419 and also 40 Encyclopedia of Polymer Science and Technology, Vol. 5, John Wiley & Sons Inc., New York, 1966, page 847ff.).

13 Thus the prior art advises, in the context of the feed process, including a defined fine seed polymer dispersion in the initial charge to the polymerization vessel and then grafting the monomers onto the seed particles. In this system the seed polymer particles act as 'polymerization nuclei'. During the emulsion polymerization it is possible if 5 appropriate to add further seed dispersion in order to obtain broader size distributions (on this point cf., for example, DE-A-42 13 965). Instead of a defined seed latex being added it can also be generated in situ. For that purpose, for example, a portion of the monomers, together with emulsifier, is introduced as initial charge and copolymerized, forming a relatively fine latex. Subsequently, in the same polymerization vessel, the 10 polymerization proper is conducted by the feed process (see also DE-A-42 13 965). The manner in which the initiator is added to the emulsion polymerization is not critical. The initiator can all be included in the initial charge to the polymerization vessel or else can be added, continuously or in stages, at the rate at which it is consumed, in the course 15 of the emulsion polymerization. The procedure depends both on the chemical nature of the initiator and on the polymerization temperature and can be chosen by the skilled worker in accordance with what is required. Preference is given to continuous or staged metering into the reaction mixture. 20 Polymerization pressure and polymerization temperature are likewise of minor importance. In general the temperatures set are between 40 and 120*C, preferably from 50 to 950C and more preferably between 70 and 90*C. Following the polymerization reaction proper it is generally necessary to remove 25 odoriferous substances, such as residual monomers and other volatile organic constituents, from the aqueous polymer dispersion of the invention. This can be done conventionally by combining a chemically acting postpolymerization system with a distillative process, optionally in succession or simultaneously. 30 Lowering the residual monomer content can also be performed chemically by free-radical postpolymerization, in particular under the action of redox initiator systems, as set out for example in EP-A-1 021 468, DE-A-44 35 423, DE-A-44 19 518 and in DE-A-44 35 422. Particularly suitable oxidizing agents for redox-initiated postpolymerization include hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide or alkali metal 35 peroxodisulfates. Suitable reducing agents are sodium disulfite, sodium hydrogensulfite, sodium dithionite, formamidinesulfinic acid, mercaptoethanol, sodium hydrogensulfite in aqueous acetone, ascorbic acid, isoascorbic acid and reducing sugar compounds. Sodium hydroxymethanesulfinate is possible but is not used preferably, owing to the release of formaldehyde. 40 Postpolymerization with the redox initiator system is carried out in the temperature range from 10 to 100*C, preferably at 20 to 900C. The redox partners can be added to the 14 aqueous dispersion independently of one another in their entirety, in portions, in alternation or continuously over a period of 10 minutes to 4 hours. To improve the postpolymerization effect of the redox initiator systems it is also possible to add soluble salts of metals of changing valence to the dispersion, such as iron, copper or vanadium 5 salts. Frequently complexing agents as well are added, which keep the metal salts in solution under the reaction conditions. Disruptive by-products can be removed distillatively in conventional manner by prolonged contact of the dispersion with a gas in finely divided form. The turbulently distributed gas 10 bubbles in the dispersion are capable of absorbing volatile odoriferous substances as a result of the continual interfacial contact, and hence of depleting them. The most common depleting gases are humidified air or nitrogen, carbon dioxide or steam. The depletion temperature and period of time depend on the components to be depleted, their volatility, solubility and concentration. Depletion is carried out preferably at a temperature of 40 to 15 950C for a total exposure time of 3 to 6 hours. With great preference steam is used (steam distillation), in which case it is generally necessary to set a steam:dispersion ratio of 3 to 10, preferably between 4 and 6. Depending on the volatility of the components the depletion is carried out industrially under superatmospheric pressure or under a slight vacuum, in the laboratory preferably at ambient pressure. The effectiveness of the 20 measures is checked via the VOC (volatile organic compounds) fraction, which is determined by means of gas chromatography with an injection temperature of 2500C. At that temperature all of the volatile organic components which have a boiling point of below 250'C, and in total account for the odor of the product, are vaporized. 25 It is preferred at the end to neutralize the polymer dispersion with a low-odor base, preferably with alkali metal or alkaline earth metal hydroxides, alkaline earth metal oxides or nonvolatile amines. The nonvolatile amines include, in particular, ethoxylated diamines or polyamines, such as are available commercially, for example, under the name Jeffamine (Texaco Chemical Co.). Preferably, however, neutralization is carried out with 30 aqueous sodium or potassium hydroxide solution so as to give, preferably, a pH of about 6.5 to 9. On the basis of their mode of preparation the aqueous polymer dispersions of the invention are almost completely free from solvents, residual monomers or other volatile 35 constituents and are therefore low in odor and low in emissions. On the basis of their low MFFT they can also be formulated without solvents and/or coalescers. The number-average diameter of the polymer particles in the aqueous polymer dispersion, as determined by quasielastic light scattering (ISO standard 13 321), is 40 preferably in the range from 80 to 300 nm, more preferably in the range from 100 to 200 nm. The polymer particles generally have a monomodal size distribution. The light transmittance of the dispersions is generally in the range from 40% to 90%, preferably in 15 the range from 45% to 70%, in a 0.01% by weight dilution. The light transmittance of a dilute dispersion correlates over wide ranges with the size of the dispersed particles; in other words, the greater the LT (light transmittance of 0.01% by weight sample in a standard commercial photometer) the smaller the diameter of the dispersed particles. 5 The present specification further provides a process for preparing binders by free radically initiated aqueous emulsion polymerization. The present specification further provides coating materials comprising the binder of the 10 invention. The present specification further provides for the use of the coating materials of the invention as an emulsion paint, polymer dispersion plaster, tile adhesive or sealant, in combination if appropriate with a silicone emulsion and/or silicate solution. 15 The coating materials of the invention possess high wet scrub resistance, good soiling behavior, can be formulated free of solvent and film former, and contain no critical components - that is, components objectionable from the standpoint of health. 20 Applications and compositions of the coating materials: The polymer dispersions of the invention are suitable for preparing low-emission and solvent-free coating materials. By coating materials are meant, for example, polymer dispersion plasters, tile adhesives, and paints, especially low-emission emulsion paints. 25 The polymer dispersions of the invention are of preferential suitability for low-emission coating materials, having a high pigment content (PVC), preferably having a PVC above 60% and in particular above 70%, especially emulsion paints such as are used for interior paints for walls, ceilings and floors. At lower PVC as well, however, i.e., in ranges from 35% to 65%, emulsion paints can be obtained as well, such as are used preferably for 30 masonry paints. They are therefore suitable for elastic coatings or, following the addition of appropriate components (silicone emulsions or potassium waterglass), as a basis for silicone resin paints or silicate paints (0. Wagner, Farbe&Lack, 1991 series, Volume 97, page 109ff., and W. Heckl, STUCK 1982 (5) 28-30). On account of their good hydrophobic and nontackifying properties they are also suitable as binders for leather or 35 textile fibers. Coating materials of this kind are known in principle to the skilled worker. An exhaustive description of aqueous polymer dispersion paints can be found for example in Ullmanns Enzyklopadie der Technischen Chemie, VCH Weinheim, 1978, 4th ed., Volume 15, page 40 664ff.

16 The low-emission coating materials of the invention comprise at least one binder of the invention, and also fillers, pigments and, if appropriate, further customary auxiliaries. The coating materials of the invention are, by way of example, emulsion paints, tile 5 adhesives or plasters. Fillers and pigments are solid substances in the coating material, with the ability to alter chemical and physical properties by interaction at the coating surface and by their inherent properties, such as hardness, particle size, particle morphology, color, gloss, 10 and so on. They may be spherical, cubic, acicular, fibrous or else platelet-shaped in form. Examples of suitable fillers include naturally occurring silicates or aluminum silicates or magnesium silicates, such as kaolin, talc, siliceous earths, mica or alkaline earth metal carbonates, preferably calcium carbonate in the form of calcide, chalk or dolomite. Mention may additionally be made of oxides and hydroxides, such as quartz flour, 15 aluminum trihydroxide, magnesium hydroxide or calcium hydroxide. Precipitated silica or silicates or pyrogenic silica are synthetically obtainable fillers which can be used and prepared in a targeted way in respect in particular of their particle size and particle size distribution. 20 A typical pigment is, for example, titanium dioxide, preferably in the rutile form. Other white or colored pigments are familiar as well, such as zinc oxide, barytes, carbon black or graphite. Synthetic organic hollow pigments are likewise known and are usually used in a blend with white pigments. Highly abrasion-resistant materials such as a-aluminum oxide, boron carbide or silicon carbide are employed in a small amount in finely ground form 25 in specialty applications. Tinting colors, however, may also comprise colored pigments, examples being iron oxides. The customary auxiliaries include wetting agents, such as sodium or potassium polyphosphates, polyacrylic acids, their alkali metal salts, polyvinyl alcohols, and so on. 30 Fillers and pigments are usually always used in mixtures. Their average particle size (expressed as the d50 value) lies preferably in the range from 1 to 50 pm, but in the form of what are called coarse fillers can also be up to 200 pm. In plasters it is usual to use even coarser fillers. 35 The coating materials further generally comprise substances which modify the viscosity, examples being cellulose ethers, such as hydroxyethylcellulose, and associative thickeners. It is possible additionally to add dispersants, defoamers, preservatives or hydrophobicizers and also dyes, UV stabilizers, antiblocking agents, flame retardants, leveling agents, fibers or other constituents to the coating materials. In order to obtain particular effect it is of course 40 also possible if appropriate to add solvents, antifreeze agents or film-forming auxiliaries to the formulation, these components being used by the skilled worker in order to prolong the open time or for low-temperature application. For exterior applications it is common to add silicone 17 emulsions as well, which distinctly enhances the water resistance of the coating materials. Systems of this kind are known for example from A. Lork, Farbe&Lack, 2002 series, Volume 108, page 97ff. 5 The solvent-free, low-emission coating materials of the invention score over their existing counterparts by high abrasion resistance, even in conjunction with high pigment volume concentrations, for example, at a PVC of 75% (according to DIN 53 778), and a high stability on storage. High abrasion resistance for a given PVC is an indicator of a good pigment binding capacity. High abrasion resistance denotes an abrasion of less than 100 pm, 10 preferably of less than 60 pm, more preferably of less than 40 pm, in the wet scrub resistance test. In addition the binders of the invention are particularly silicate compatible and stable on storage. 15 The examples given below are intended to illustrate the invention, though without restricting it. Analysis and test methods: 20 average particle diameter: The average diameter of the polymer particles was determined by dynamic light scattering (DLS) on a 0.01% by weight aqueous dispersion at 23 0 C using an Autosizer IIC (Malvem 25 Instruments, UK). The parameter reported is the average diameter of the cumulant evaluation (cumulant z-average) of the measured autocorrelation function (ISO standard 13 321) in nm. Minimum film-forming temperature (MFFT): 30 The minimum film-forming temperature MFFT was determined by a method based on DIN 53 787. The measuring instrument used was a film-forming bar (a metal plate to which a temperature gradient is applied). Filming took place at a wet film thickness of 1 mm. The minimum film-forming temperature reported is the temperature at which the film begins to 35 become fissured (cf. Ullmanns Enzyklopadie der technischen Chemie, 4th ed., Vol. 19, Verlag Chemie, Weinheim (1980), page 17). Solids content (SC): 40 The solids content (SC) was determined gravimetrically by drying a sample in a drying oven at 140*C for half an hour. The parameter reported is in each case the mean of two measurements.

18 Viscosity: The viscosity was measured in a rotational viscometer at 23*C in accordance with DIN EN 5 ISO 3219, at a shear rate of 100/s, and is reported in mPas. Wet scrub resistance: The wet scrub resistance was tested in accordance with the currently valid ISO 13 300. A 10 coating bar 60 mm wide was used to draw down a paint film with a dry thickness of approximately 100 pm onto a Leneta chart measuring approximately 430 x 80 mm. This film was stored under standard conditions at room temperature for 7 days. Then a moistened scrub pad was passed over the coating in a scrub tester instrument from Ericson. After 200 double rubs (scrub cycles) the paint abrasion determined 15 gravimetrically, with knowledge of the scrubbed area, was converted into an average abrasion per unit area and expressed in pm of abrasion. The lower the pm figure, the more scrub-resistant the coating. For greater ease of comparability the results are expressed in pm of abrasion and not in the form of the classes specified by the standard. 20 Stability on storage (SOS disp.; SOS paint): A measure used for the stability of the formulation material was the change in viscosity (difference in mPas), on the one hand of the pure dispersion (SOS disp.), on the other hand of the formulated paint (SOS paint), before and after 14-day storage in a closed 25 container holding about 100 ml of paint in a drying cabinet at 50 0 C. It is desirable for the viscosities of the dispersion (see table 4) and of the paint (see table 5) to change only minimally as a consequence of this hot storage, which is intended to simulate a prolonged period of storage. An increase or decrease in viscosity by more than +/-5% after this treatment indicates that during the storage of the product the quality of the paint 30 takes an adverse course. Silicate compatibility (WG COM): In certain examples the compatibility against waterglass (WG COM) was tested. In the 35 preparation of silicate paints a waterglass solution is mixed into the paints, and drastically increases their pH. A desirable compatibility is reflected in a score of less than 2. Water absorption (WA): 40 Often employed for masonry paints is the water absorption (WA) of the pure dispersion film. This figure is obtained by gravimetric weight increase of a 25 cm 2 dispersion film about 1 mm thick, dried at room temperature, after 24 h of water storage (at 23 0 C). The 19 higher the result the greater the water absorption of a masonry paint based on this binder. High water absorption ought as far as possible to be prevented, in order to save on expensive silicone compounds, whose addition is necessary in order to limit the water absorption. 5 Emulsifiers used: Emulsifier solution A: 20% strength by weight solution of an isotridecyl ethoxylate with 8 mol of EO 10 Emulsifier solution B: 40% strength by weight solution of a sodium salt of a C14 alkanesulfonate Emulsifier solution C: 45% strength by weight solution of Dowfax@ 2A1 Emulsifier solution D: approximately 30% strength by weight solution of a sodium salt of a C12/C14 alkane triglycol ether sulfate 15 Emulsifier solution E: 30% strength by weight solution of a sodium salt of a sulfated ethoxylated C12/C14 fatty alcohol with about 25 mol of EO 20 Examples: Example 1: 5 General instructions for preparing the inventive polymer dispersions A 2 I polymerization vessel with stirrer and reflux condenser was charged with 180.3 g of deionized water and 10 8.9 g of an aqueous polystyrene latex (polymer solids content 33% by weight, number-average particle diameter about 30 nm) and this initial charge was heated with stirring to 850C. Then 2.5 g of a solution of 1 g of sodium peroxodisulfate in 40 g of water were added, and after 5 minutes the continuous 15 metered addition was commenced of the remainder of the solution, over the course of 4 hours, and of the monomer emulsion feedstream 1-1, over the course of 3.5 hours. Following complete addition, reaction was left to continue for 1 hour and then the batch was cooled to 70 0 C. Over the course of 3 hours, continuously, via two separate feedstreams, 21.2 g of a 4.7% strength by weight aqueous solution of tert-butyl 20 hydroperoxide and 19.5 g of a 0.19% strength by weight aqueous solution of ascorbic acid were metered in and stirring was continued for a further hour, during which the temperature was maintained. Feedstream 1-1: 25 90 g of deionized water 20 g of emulsifier solution A 20 g of emulsifier solution B 245 g of ethylhexyl acrylate (monomer A) 30 245 g of styrene (monomer B) 71.4 g of 7% strength by weight aqueous itaconic acid (monomer C) 5 g of methacrylic acid (monomer C) Steam was let down into the dispersion at 70 0 C and taken off via a top-mounted 35 condenser, and condensed (with weighing). The steam treatment was controlled so as to give a total of 350 g of steam condensate over 3 hours of continuous treatment. Subsequently the reaction mixture was cooled to room temperature, adjusted to a pH of 7.6 using 10% strength by weight sodium hydroxide solution and filtered through a metal filter with a mesh size of 250 pm. This gave a virtually coagulum-free and odorless 40 polymer dispersion, whose composition and characteristic physical data are summarized in tables 2 and 3.

21 By gas chromatography 130 ppm of residual monomer and less than 600 ppm of volatiles, based on the total mass, were found. General instructions for preparing the inventive emulsion paints 5 The inventive emulsion paints were prepared by blending the components indicated in table 1 in the order stated therein, using a dissolver. The varying solids content of the polymer dispersions employed was taken into account in the quantity used and was made such that the formulation contained approximately 110 parts by weight of 10 dispersion. The formulations were adjusted so as to have a pigment volume concentration (PVC) of 79% (the PVC was calculated by the formula indicated above; the individual volumes were obtainable from the given amounts, via the respective densities). Table 1.: Formulation with PVC=79% of the inventive emulsion paints 15 Parts by Component weight 300 deionized water 1 20% strength aqueous sodium hydroxide solution 3.6 thickener, cellulose ether; Natrosol@ 250 HR, Hercules GmbH 5 Pigmentverteiler MD 20 (pigment dispersant); 25% strength by weight aqueous solution of a sodium salt of a maleic acid-diisobutene copolymer, BASF AG 3 preservative (Parmetol@ A 26, Schalke & Mayr GmbH, Norderstedt) 4 defoamer; Byk@ 037, Byk 70 pigment; titanium dioxide Kronos 2300, Kronos Titan GmbH, Leverkusen 5 finely divided aluminum silicate P 820, Degussa AG, Frankfurt. 235 Omyacarb@ 5 GU filler, calcium carbonate, average particle diameter 5 pm; Omya GmbH, Cologne 55 Sokal P2, precipitated, uncoated calcite, average particle size 200 300 nm, Solvay Chemicals, Rheinberg 100 Omya Violette, fine calcium carbonate in powder form, average particle diameter 98% < 20 pm, 14% < 1 pm, Omya GmbH, Cologne 65 Finntalc M 15, talc, average particle diameter 4.5 pm, Omya GmbH, Cologne 2 defoamer; Byk@ 037, Byk 110 polymer dispersion about 42 deionized water resulting from the different water contents of the individual aqueous polymer dispersions 22 The wet scrub resistance test results and the stability results are summarized in table 4. Example 2: 5 As example 1 but using 107.1 g of itaconic acid solution and 2.5 g of methacrylic acid as monomers C. Example 3: 10 As example 1 but using 107.1 g of itaconic acid solution and 2.5 g of acrylic acid as monomers C. Example 4: 15 As example 1 but using 142.8 g of itaconic acid solution as monomer C. Example 5: As example 1 but using 178.5 g of itaconic acid solution as monomer C. 20 Example 6: As example 1 but using 5.0 g of acrylic acid as monomer C. 25 Example 7: As example 1 but using monomer emulsion 7-1. Feedstream 7-1: 30 180 g deionized water 11.11 g emulsifer solution C 8.93 g emulsifier solution D 246.5 g ethylhexyl acrylate (monomer A) 246.5 g styrene (monomer B) 7 g acrylic acid (monomer C) Examples 8 to 10: As example 7 but using increasing amounts of acrylic acid as the acid component, as per 35 table 2.

23 Example 11: A 2 I polymerization vessel with stirrer and reflux condenser was charged with 5 120.2 g of deionized water and 10.6 g of an aqueous polystyrene latex (polymer solids content 33% by weight, number-average particle diameter about 30 nm) and this initial charge was heated with stirring to 85 0 C. Then 4 g of a solution of 0.3 g of 10 sodium peroxodisulfate in 45 g of water were added, and after 5 minutes the continuous metered addition was commenced of the remainder of the solution, over the course of 4.5 hours, and of the monomer emulsion 11-1, over the course of 4.5 hours. Following complete addition, reaction was left to continue for 1 hour and then the batch was cooled to 70 0 C. Over the course of 3 hours, continuously, via two separate feedstreams, 16.0 g 15 of a 8.7% strength by weight aqueous solution of tert-buty hydroperoxide and an aqueous mixture of 3.7 g of a 40% strength by weight solution of sodium disulfite and 1.0 g of acetone in 15.8 g of water were metered in. Following complete addition, stirring was continued for a further hour. 20 Feedstream 11-1: 284.8 g of deionized water 25 g of emulsifier solution C 20 g of emulsifier solution B 25 348.8 g of ethylhexyl acrylate (monomer A) 341.8 g of styrene (monomer B) 10.5 g of acrylic acid (monomer C) Steam was let down into the dispersion after a waiting time of 1 h and taken off via a top 30 mounted condenser, and condensed (with weighing). The steam treatment was controlled so as to give a total of 520 g of steam condensate over 3 hours of continuous treatment. Subsequently the reaction mixture was cooled to room temperature, adjusted to a pH of 7.6 using 10% strength by weight sodium hydroxide solution, admixed with 3.1 g of a liquid benzophenone mixture and filtered through a metal filter with a mesh size 35 of 250 pm. This gave a coagulum-free and odorless polymer dispersion, whose characteristic physical data are summarized in table 4. By gas chromatography 200 ppm of residual monomer and less than 800 ppm of volatiles, based on the total mass, were found. 40 Examples 12-17: 24 As example 6 but with monomer composition as per table 2. Example 18: 5 Example 8 is repeated with the difference that by using more emulsifier and a greater amount of initial polystyrene latex charge a more finely divided dispersion is obtained. The dispersion has on average a particle size of 144 nm. Example 19: 10 Example 3 is repeated using monomer emulsion 19-1. Following complete addition of the emulsion it is held at 850C for 30 minutes, a mixture of 1.5 g of acrylic acid and 1.5 g of water is added additionally, and the batch is held at 850C for 30 minutes more, after which the procedure matches that described in example 1. 15 Feedstream 19-1: 210 g deionized water 13.3 g emulsifier solution C 8.6 g emulsifier solution D 300 g ethylhexyl acrylate (monomer A) 288 g styrene (monomer B) 3 g acrylic acid (monomer C) Example 20: 20 As example 12 but with addition of 1.2 g of methacryloyloxypropyltrimethoxysilane. Examples 21 to 24 (comparative examples): 25 In comparative examples 21 to 24 the polymer dispersions of examples 1 to 4 from DE A-102 06 994 were reworked. Sodium acetate was used as the buffer substance. Examples 25 to 27 (comparative examples): 30 In comparative examples 25 to 27 the polymer dispersions of comparative example 1, example 1 and 4 of EP-A-1 134 240 were reworked. Example 28 (comparative example): 35 In comparative example 28 a polymer dispersion was used that was prepared using a higher fraction of acrylic acid (4% by weight based on total polymer).

25 The polymer dispersions of examples 21 to 28 were used for preparing emulsion paints in accordance with the standard formulation in example 1, and were compared with the inventive polymer dispersions (see table 4). 5 Table 2: Composition of the inventive dispersions (binders) Example EHA S IA MAA AA BA MMA AN HEA AAEMA BDA2 MEMO AM %% % % % % % % % % % % 1 49 49 1 1 2 49 49 1.5 0.5 3 49 49 1.5 0.5 4 49 49 2 5 48.8 48.8 2.5 6 49 49 1 1 7 49.3 49.3 1.4 8 49 49 2 9 48.8 48.8 2.4 10 48.7 48.7 2.7 11 50.5 48.2 1.3 12 25 48 2 25 13 49 2 49 14 49 49 2 0.1 15 48 40 2 8 2 16 48 48 2 2 17 51 37 2 10 18 50 48 2 19 50 48 2 20 25 47.9 2 25 0.2 21*) 53 44.5 2.4 22*) 41.8 2.5 0.3 55.4 23*) 52.3 46.3 0.3 1.1 24*) 41.9 2.5 55.6 25*) 58.8 41.2 26*) 58.8 41.2 0.01 27*) 58.6 0.3 41 0.01 28*) 24 48 424 *) comparative experiment 10 EHA 2-ethylhexyl acrylate 26 S styrene IA itaconic acid MAA methacrylic acid AA acrylic acid 5 BA n-butyl acrylate MMA methyl methacrylate AN acrylonitrile HEA hydroxyethyl acrylate AAEMA 2-acetoacetoxyethyl methacrylate 10 BDA2 butanediol diacrylate MEMO methacryloyloxypropyltrimethoxysilane AM acrylamide The percentages are by weight. 15 Table 3: Properties of the inventive dispersions (binders) Example SC pH Visc. LT DLS Coag. wt.% mPas % nm % 1 49.9 7.6 42 57 168 0.1 2 49.3 7.5 28 58 171 0.1 3 48.8 7.6 35 58 168 0.1 4 48.2 7.5 26 57 170 0.1 5 47.7 7.5 22 58 169 0.1 6 49.6 7.6 40 54 178 0.4 7 49.7 7.3 48 55 174 0 8 49.4 7.5 48 57 173 0 9 49 7.5 72 61 164 0.1 10 49 7.5 70 55 177 0.2 11 50.3 7.6 52 51 193 0 12 53.2 7.4 70 52 191 0 13 52.9 8.2 380 67 198 0 14 52.9 7.3 85 51 192 0 15 53.2 6.6 287 54 191 0 16 52.5 7.0 93 50 192 0 17 51.1 7.4 69 55 189 0 18 49.1 7.2 n.d. 71 144 0 19 49 7.1 n.d. 52 186 0 20 53.4 7.4 124 52 183 0 21*) 51 7.3 600 91 91 0.1 22*) 50.8 7.1 550 92 100 0.1 27 23*) 49 7.4 315 65 180 1 24*) 49.7 7.1 495 92 100 0.1 25*) 48.2 8.6 35 64 162 0.1 26*) 43.3 7.5 17 62 156 0 27*) 41.9 8.0 13 63 164 0.1 28*) 53.8 7.2 160 54 189 0 *) comparative experiment n.d. not determined 5 Table 4: Properties of the inventive emulsion paints Example SOS disp WG COM WA Visc. paint SOS paint Scrub resistance mPas score % mPas mPas pm 1 -1 0 7 700 -190 32 2 2 0 7.9 761 -193 35 3 2 0 9.2 751 -212 36 4 2 0 8.2 782 -1258 34 5 3 0 10.2 800 240 41 6 3 0 9.2 623 16 29 7 1 4 5.3 751 76 26 8 -1 0 5.9 753 10 30 9 -2 0 6.5 774 126 32 10 0 0 7.7 781 170 37 11 2 0 6.6 771 80 34 12 10 0 7.0 686 96 36 13 -50 1 24.9 730 -23 81 14 3 0 4.7 724 103 37 15 -31 0 27.6 660 80 45 16 -6 0 4.8 712 36 60 17 -1 0 25.7 645 -52 62 18 n.d. 0 5.2 1460 740 29 19 n.d. 0 23.0 1050 -225 40 20 8 0 9.7 534 42 46 21*) -53 0 11.4 960 bodied 41 22*) -29 0 19.4 1240 bodied 47 23*) -18 0 30.6 870 51 94 24*) -47 0 24.8 964 256 43 25*) -3 5 5 1980 1950 56 28 26*) -3 5 7.5 2330 1970 64 27*) -2 5 8.4 644 186 40 28*) -22 0 20.8 888 bodied 67 *) comparative experiment Example 29: 5 Preparation of a synthetic resin float plaster based on the polymer dispersion from example 11. A synthetic resin plaster was made up according to the following formulation (table 5). 10 Table 5: Formulation of an inventive polymer dispersion plaster Parts by Component weight 96 dispersion from example 11 9 Calgon@ N, sodium polyphosphate, 25% strength by weight 3 preservative (Parmetol@ A 26, Schulke & Mayr GmbH, Norderstedt) 3 Agitan@ 280, defoamer, Monzig Chemie, Heilbronn 40 Tylose@ MH 6000 XP, 4% strength by weight solution, Clariant AG 5 Basophob@ WDS, hydrophobicizer, BASF AG 30 pigment Kronos@ 2043, Kronos Titan GmbH, Leverkusen 64 water 425 Omyacarb@ 40 GU, filler, calcium carbonate, Omya GmbH, Cologne 225 Omyacarb@ 130 GU, GU filler, calcium carbonate, Omya GmbH, Cologne 60 Plastorit@ 0, natural mineral mixture, average particle size 40 pm, Luzenac-Naintsch, Austria 40 quartz sand 1.5-2.0 mm, Quarzwerke Frechen The synthetic resin plaster was applied to an area of approximately 1 m 2 and the processing properties were compared with those of Acronal S 559 and scored 15 accordingly, 0 denoting advantageous and 5 denoting poor.

29 Property Comparative Inventive (Acronal@ S 559, BASF Aktiengesellschaft, DE) In-can appearance very pasty (4) doughy (2) Application/processing good (2) good (1) Rub-off after 5 min slight smearing (1) much smearing (3) Appearance after drying good (1) good (1-2) Pinholes 1 1-2 Microcracks 1 1-2 Water absorption after 24 h 16.7% 8.7% of water storage Example 30: 5 A silicate paint was made up according to the following formulation (table 6). Table 6: Formulation of an inventive silicate paint Parts by Component weight 232 deionized water 2 Sapetin@ D 20 2 Betolin@ Quart 25, weakly cationized stabilizer additive, approximately 16% strength by weight solution, Woellner Silikat GmbH, Ludwigshafen 2 Agitan@ 280, defoamer, M~nzig Chemie, Heilbronn 2 Rhodopol@ 50 MD, Rhone-Poulenc Chemie GmbH, Frankfurt 100 pigment; titanium dioxide Kronos@ RN 2043, Kronos Titan GmbH, Leverkusen 100 polymer dispersion from example 7 100 Millicarb@, filler, Omya GmbH, Cologne 40 talc AT 1 100 Pastorit@ 0000, natural mineral mixture, average particle size 7.5 pm, Luzenac-Naintsch, Austria 70 Plastorit@ 0, natural mineral mixture, average particle size 40 pm, Luzenac-Naintsch, Austria 250 Betolin@ P 35, approximately 35% strength by weight solution of potassium waterglass, Woellner Silikat GmbH, Ludwigshafen 30 The paint had a solids content of about 50% by weight and good processing properties. According to the DIN method (180 pm drawdown wet, 7 days' drying) 2060 scrub cycles were achieved. After 14 days of storage of the silicate paint at 50 0 C, when the scrub test was repeated a value of 2470 cycles was obtained, which suggests excellent stability on 5 storage. The capillary water uptake (DIN 52 617) was 1.81 kg/m 2 /ho 2 IN THE MATTER OF an Australian Application corresponding to PCT Application PCT/EP2005/003219 RWS Group Ltd, of Europa House, Marsham Way, Gerrards Cross, Buckinghamshire, England, hereby solemnly and sincerely declares that, to the best of its knowledge and belief, the following document, prepared by one of its translators competent in the art and conversant with the English and German languages, is a true and correct translation of the amended sheets of the PCT Application filed under No. PCT/EP2005/003219. Date: 26 July 2006 C. E. SITCH Deputy Managing Director - UK Translation Division For and on behalf of RWS Group Ltd 31 Claims 1. A binder comprising at least one addition polymer obtainable by free-radically initiated aqueous emulsion polymerization of a mixture of ethylenically 5 unsaturated monomers composed of 20 to 60% by weight of 2-ethylhexyl acrylate (monomer A) 0 to 40% by weight of one or more monomers each of whose homopolymer has a glass transition temperature <10*C (monomers B), 10 45 to 55% by weight of at least one monomer whose homopolymer has a glass transition temperature >500C (monomers C), 0.1 to 5% by weight of at least one monomer containing acid groups (monomers D), and 0 to 5% by weight of at least one further monomer having at least one 15 hydroxyl, keto and/or silane group in the side chain (monomers E), based in each case on the total amount of ethylenically unsaturated monomers used for the polymerization, using one or more alkylphenol ether-free emulsifiers, 20 one or more protective colloids and one or more initiators, the polymer having a minimum film-forming temperature of below 150C and comprising less than 0.01% by weight of compounds having a boiling point below 500C. 2. The binder according to claim 1, wherein monomer B is selected from the group 25 consisting of C1 to C10 alkyl acrylates, C, to C10 alkyl methacrylates, C5 to C12 cycloalkyl acrylates and C5 to C12 cycloalkyl methacrylates. 3. The binder according to claim 1 or 2, wherein monomer C is selected from the group consisting of styrene, methyl methacrylate, tert-butyl methacrylate, tert 30 butyl acrylate, lauryl acrylate and stearyl acrylate. 4. The binder according to claim 1 or 2, wherein monomer C is styrene. 5. The binder according to any one of claims 1 to 4, wherein monomer D is selected 35 from the group consisting of acrylic acid, methacrylic acid, itaconic acid, acrylamido-2-methylpropanesulfonic acid, maleic acid and fumaric acid. 6. The binder according to any one of claims 1 to 4, wherein monomer D is acrylic acid. AMENDED SHEET 32 7. The binder according to any one of claims 1 to 6, wherein the polymer has a minimum film-forming temperature of not more than 10*C and is free from film forming auxiliaries and/or solvents. 5 8. The binder according to any one of claims 1 to 7, wherein the polymer is composed of particles whose number-average diameter is 80 to 300 nm. 9. The binder according to any one of claims 1 to 8, used as an aqueous polymer dispersion having a solids fraction of 25 to 70% by weight. 10 10. The binder according to claim 9, wherein the aqueous polymer dispersion has a pH of 6.5 to 9. 11. The binder according to any one of claims 1 to 10, wherein the polymer 15 comprises less than 0.01% by weight of unreacted monomers A to E, based on the total mass of monomers used. 12. The binder according to any one of claims 1 to 11, wherein the polymer comprises less than 0.1% by weight of volatile organic compounds having a 20 boiling point below 2500C, based on the total mass of monomers used, excluding the fraction of water. 13. A process for preparing a binder according to any one of claims 1 to 12, which comprises reacting a mixture of ethylenically unsaturated monomers composed 25 of 20 to 60% by weight of 2-ethylhexyl acrylate (monomer A) 0 to 40% by weight of one or more monomers each of whose homopolymer has a glass transition temperature <10*C (monomers B), 30 45 to 55% by weight of at least one monomer whose homopolymer has a glass transition temperature >500C (monomers C), 0.1 to 5% by weight of at least one monomer containing acid groups (monomers D), and 0 to 5% by weight of at least one further monomer having at least one 35 hydroxyl, keto and/or silane group in the side chain (monomers E), based in each case on the total amount of ethylenically unsaturated monomers used for the polymerization, using one or more alkylphenol ether-free emulsifiers, 40 the polymer having a minimum film-forming temperature of below 15*C, by free radically initiated aqueous emulsion polymerization, no use being made during the preparation of any compounds having a boiling point below 50*C or of any AMENDED SHEET 33 compounds able through hydrolysis to give off compounds having a boiling point below 50'C. 14. A coating material comprising at least one binder according to any one of claims 5 1 to 12 and also fillers, pigments and, if appropriate, further customary auxiliaries. 15. The coating material according to claim 14, having a pigment volume concentration of at least 60% by weight, based on the total mass. 10 16. The coating material according to claim 14 or 15, the dried and filmed polymer film after 24 hours of water storage exhibiting a water absorbency of less than 10% of the weight of the polymer film. 15 17. The use of a coating material according to any one of claims 14 to 16 as an emulsion paint. 18. The use according to claim 17, the emulsion paint further comprising a silicone emulsion and/or silicate solution. 20 19. The use of a coating material according to any one of claims 14 to 16 as a polymer dispersion plaster. 20. The use of a coating material according to any one of claims 14 to 16 alone or in 25 combination with a silicone emulsion as a tile adhesive or sealant. AMENDED SHEET

Claims (20)

1. A binder comprising at least one addition polymer obtainable by free-radically initiated aqueous emulsion polymerization of a mixture of ethylenically 5 unsaturated monomers composed of 20 to 60% by weight of 2-ethylhexyl acrylate (monomer A) 0 to 40% by weight of one or more monomers each of whose homopolymer has a glass transition temperature <10 0 C (monomers B), 10 30 to 70% by weight of at least one monomer whose homopolymer has a glass transition temperature >50 0 C (monomers C), 0.1 to 5% by weight of at least one monomer containing acid groups (monomers D), and 0 to 5% by weight of at least one further monomer having at least one 15 hydroxyl, keto and/or silane group in the side chain (monomers E), based in each case on the total amount of ethylenically unsaturated monomers used for the polymerization, using one or more alkylphenol ether-free emulsifiers, 20 one or more protective colloids and one or more initiators, the polymer having a minimum film-forming temperature of below 15 0 C and comprising less than 0.01% by weight of compounds having a boiling point below 50*C.

2. The binder according to claim 1, wherein monomer B is selected from the group 25 consisting of C 1 to C 10 alkyl acrylates, C 1 to C 1 0 alkyl methacrylates, C 5 to C 12 cycloalkyl acrylates and C 5 to C 12 cycloalkyl methacrylates.

3. The binder according to claim 1 or 2, wherein monomer C is selected from the group consisting of styrene, methyl methacrylate, tert-butyl methacrylate, tert 30 butyl acrylate, lauryl acrylate and stearyl acrylate.

4. The binder according to claim 1 or 2, wherein monomer C is styrene.

5. The binder according to any one of claims 1 to 4, wherein monomer D is selected 35 from the group consisting of acrylic acid, methacrylic acid, itaconic acid, acrylamido-2-methylpropanesulfonic acid, maleic acid and fumaric acid.

6. The binder according to any one of claims 1 to 4, wherein monomer D is acrylic acid. 40

7. The binder according to any one of claims 1 to 6, wherein the polymer has a minimum film-forming temperature of not more than 10*C and is free from film forming auxiliaries and/or solvents. 32

8. The binder according to any one of claims 1 to 7, wherein the polymer is composed of particles whose number-average diameter is 80 to 300 nm. 5

9. The binder according to any one of claims 1 to 8, used as an aqueous polymer dispersion having a solids fraction of 25 to 70% by weight.

10. The binder according to claim 9, wherein the aqueous polymer dispersion has a pH of 6.5 to 9. 10

11. The binder according to any one of claims 1 to 10, wherein the polymer comprises less than 0.01% by weight of unreacted monomers A to E, based on the total mass of monomers used. 15

12. The binder according to any one of claims 1 to 11, wherein the polymer comprises less than 0.1% by weight of volatile organic compounds having a boiling point below 250 0 C, based on the total mass of monomers used, excluding the fraction of water. 20

13. A process for preparing a binder according to any one of claims 1 to 12, which comprises reacting a mixture of ethylenically unsaturated monomers composed of 20 to 60% by weight of 2-ethylhexyl acrylate (monomer A) 25 0 to 40% by weight of one or more monomers each of whose homopolymer has a glass transition temperature <10 0 C (monomers B), 30 to 70% by weight of at least one monomer whose homopolymer has a glass transition temperature >50*C (monomers C), 0.1 to 5% by weight of at least one monomer containing acid groups 30 (monomers D), and 0 to 5% by weight of at least one further monomer having at least one hydroxyl, keto and/or silane group in the side chain (monomers E), 35 based in each case on the total amount of ethylenically unsaturated monomers used for the polymerization, using one or more alkylphenol ether-free emulsifiers, the polymer having a minimum film-forming temperature of below 15 0 C, by free radically initiated aqueous emulsion polymerization, no use being made during the preparation of any compounds having a boiling point below 50 0 C or of any 40 compounds able through hydrolysis to give off compounds having a boiling point below 50 0 C. 33

14. A coating material comprising at least one binder according to any one of claims 1 to 12 and also fillers, pigments and, if appropriate, further customary auxiliaries. 5

15. The coating material according to claim 14, having a pigment volume concentration of at least 60% by weight, based on the total mass.

16. The coating material according to claim 14 or 15, the dried and filmed polymer film after 24 hours of water storage exhibiting a water absorbency of less than 10 10% of the weight of the polymer film.

17. The use of a coating material according to any one of claims 14 to 16 as an emulsion paint. 15

18. The use according to claim 17, the emulsion paint further comprising a silicone emulsion and/or silicate solution.

19. The use of a coating material according to any one of claims 14 to 16 as a polymer dispersion plaster. 20

20. The use of a coating material according to any one of claims 14 to 16 alone or in combination with a silicone emulsion as a tile adhesive or sealant.