Aqueous polymer dispersions

Abstract

The invention relates to aqueous polymer dispersions obtainable by free-radical aqueous emulsion polymerization of ethylenically unsaturated monomers M, the monomers M comprising a) 0.5 to 7.0 wt. % of a combination of the following, based on the total weight of the monomers M: a1) at least one monomer Ma1 selected from monoethylenically unsaturated monocarboxylic acids and their salts having 3 to 6 carbon atoms; a2) at least one monomer Ma2 selected from monoethylenically unsaturated dicarboxylic acids and their salts having 4 to 8 carbon atoms; a3) at least one monomer Ma3 selected from monoethylenically unsaturated monosulfonic acids and their salts having 2 to 10 carbon atoms; b1) 60 to 79.45 wt. % of at least one monomer Mb1, based on the total weight of the monomers M; b) 20 to 39.45 wt. % of at least one monomer Mb2, based on the total weight of the monomers M, selected from nonionic monoethylenically unsaturated monomers having a solubility of up to 60 g / L in deionized water at 25° C. and 1 bar, and a homopolymer thereof having a glass transition temperature Tg of at least 50° C.; b) 0.05 to 2.0 wt. % of at least one crosslinking monomer Mc, based on the total weight of the monomers M; b) 20 to 39.45 wt. % of at least one monomer Mb2, based on the total weight of the monomers M, selected from nonionic monoethylenically unsaturated monomers having a solubility of up to 60 g / L in deionized water at 25° C. and 1 bar, and a homopolymer thereof having a glass transition temperature Tg of at most 40° C.; c) 0.05 to 2.0 wt. % of at least one crosslinking monomer Mc; wherein the aqueous emulsion polymerization is carried out at least partially in the presence of a chain transfer compound. The invention also relates to a process for preparing an aqueous polymer dispersion. The aqueous polymer dispersion can be used as a binder in an aqueous coating formulation, in particular as a binder in an aqueous coating formulation for shaped mineral articles.

Description

[0001] The invention relates to aqueous polymer dispersions obtainable by free-radical aqueous emulsion polymerization of ethylenically unsaturated monomers M comprising

[0002] a) a monoethylenically unsaturated monomer selected from the group consisting of acidic monomers,

[0003] b1) a nonionic monoethylenically unsaturated monomer Mb1 having a solubility in deionized water of at most 60 g / L at 25° C. and 1 bar, the glass transition temperature Tg of the homopolymer of which is at least 50° C., and

[0004] b2) nonionic monoethylenically unsaturated monomers Mb2 having a solubility in deionized water of at most 60 g / L at 25° C. and 1 bar and whose homopolymers have a glass transition temperature Tg of at most 40° C.

[0005] The invention also relates to a process for preparing the aqueous polymer dispersion.The aqueous polymer dispersion can be used as a binder in aqueous coating formulations, in particular as a binder in aqueous coating formulations for shaped mineral articles. Background Art

[0006] Polymer dispersions of polymerized ethylenically unsaturated monomers M are generally known, in particular as adhesive components. As adhesives, in particular in coatings, one of the important requirements for such adhesives is that they provide the coating with high mechanical strength and hardness, and therefore good mechanical shock stability and good blocking resistance. At the same time, the coating must be elastic to compensate for mechanical stresses. For exterior coatings, such as architectural coatings and coatings for molded mineral products, low water absorption and good stain resistance as well as good resistance to lichen and moss growth are also required.

[0007] A shaped mineral product is a shaped product which is essentially made of a mineral material which contains a mineral binder, in particular a cement binder. In particular, a shaped product is a product which is prepared from a hydraulic composition (e.g. a mortar) containing a mineral binder, water, aggregates and, if appropriate, pigments, auxiliaries, after being shaped by hardening of the hydraulic composition over time, if appropriate, by exposure to high temperatures. Mineral binders are finely dispersed inorganic substances, such as lime, gypsum, clay, fly ash, pozzolanic materials and / or cement, which are hydraulic, i.e. when they are mixed with water, they undergo a stone-like setting over time. In the mortar, the mineral binder also hardens or sets. Thus, the mortar undergoes a stone-like setting over time in air or under water, if appropriate, by exposure to high temperatures. A shaped mineral product, more particularly a concrete roof tile, may comprise several layers of a mineral material comprising one or more mineral binders, wherein different layers may have the same or different overall composition (see, for example, DE 3932573 and GB 2,030,890).

[0008] Examples of shaped mineral articles for coating according to the invention are concrete pipes for conveying waste water, concrete roof tiles, curbstones, steps, floor slabs, floor panels based on mineral binders, and fiber cement slabs and boards, i.e. flat shaped mineral articles filled with organic or inorganic fibers, such as polyester fibers or nylon fibers, respectively.

[0009] A particular problem associated with formed mineral products is the occurrence of weathering phenomena. These phenomena can be attributed to the presence of multivalent cations such as Ca in the mineral binder in an alkaline environment. 2+ When exposed to water, the ionic components are leached out and migrate to the surface where they react with carbon dioxide in the air and form unsightly, relatively water-insoluble white lime stains on the surface of the shaped mineral article. Weathering may occur during the actual hardening or curing of a newly prepared shaped mineral article, during storage in packaging of the mineral article or when an already hardened shaped mineral article is exposed to weathering.

[0010] In order to alleviate the above problems, a coating is often provided for the shaped mineral product. For this purpose, an aqueous coating composition in which the binder component is an aqueous polymer dispersion is usually used. Since weathering has occurred in the actual setting process of the hydraulic composition, this coating is usually applied to the shaped mineral product even before it solidifies. After solidification or solidification, it can be coated for the second time or more with paint or with a varnish material and then dried in various cases. However, the performance of the first generation of varnishes in terms of its protection against weathering is not particularly satisfactory. In addition, this type of coating is easily soiled.

[0011] The protection of shaped mineral articles from the above-mentioned weathering has been improved by coatings based on styrene / acrylate dispersions or pure acrylate dispersions, as described in EP 469295, DE 19514266, EP 821660 and DE 10343726.

[0012] The coatings of the prior art all have the disadvantage of being relatively water absorbing. Such water absorption makes low molecular weight components (such as surfactants) commonly used in the coating for the preparation of water-based formulations subject to the risk of leaching under long-term weathering. Water absorption is manifested, for example, in an increased whitening or embrittlement of the coating. In addition, water absorption leads to a reduction in the mechanical stability of the coating due to the corresponding swelling of the polymer and may also cause the leaching of emulsifiers and increase the surface smoothness, which is also undesirable for safety reasons. In addition, in the case of colored coatings, there is a risk of adverse changes in the perceived color due to the water absorption of the coating.

[0013] EP 915071 discloses a coating composition for coating shaped mineral articles, wherein the coating composition comprises as binder an aqueous polymer dispersion based on ethylenically unsaturated monomers comprising from more than 0.2% to 5% by weight of itaconic acid and having reduced water absorption.

[0014] WO 2009 / 080614 discloses aqueous polymer dispersions prepared from monomers M comprising acidic monomers and monomers Mb1 and Mb2 by free radical emulsion polymerization using a gradient feed technique, wherein different monomers (particularly acidic monomers) are fed at different dosage rates for emulsion polymerization. Although the polymer dispersions result in reduced water absorption, there is still room for improvement. Summary of the invention

[0015] An object of the present invention is to provide a binder for aqueous coating compositions suitable for exterior applications, in particular for coatings for shaped mineral articles such as concrete roof tiles, paving slabs and fiber cement coatings, which provides low water absorption. Furthermore, even with long-term exposure to moisture and / or sunlight, the visual appearance of such coatings should not be adversely altered. Furthermore, the binder should be formulated into aqueous coatings and varnishes to produce good coating properties, such as high mechanical strength, high weathering resistance, low blushing tendency and good stain resistance / fouling resistance, resistance to lichen and moss growth and exhibit good film-forming properties.

[0016] Surprisingly, it has been found that the abovementioned problems can be solved by aqueous polymer dispersions obtainable by free-radical aqueous emulsion polymerization of ethylenically unsaturated monomers M comprising

[0017] a) 0.5 to 7.0% by weight of the following combinations, based on the total weight of the monomers M

[0018] a1) at least one monomer Ma1 selected from monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms and their salts;

[0019] a2) at least one monomer Ma2 selected from monoethylenically unsaturated dicarboxylic acids having 4 to 8 carbon atoms and their salts;

[0020] a3) at least one monomer Ma3 selected from monoethylenically unsaturated monosulfonic acids having 2 to 10 carbon atoms and their salts;

[0021] b1) 60 to 79.45% by weight of at least one monomer Mb1, based on the total weight of the monomers M, chosen from nonionic monoethylenically unsaturated monomers having a solubility in deionized water at 25° C. and 1 bar of up to 60 g / L and whose homopolymers have a glass transition temperature Tg of at least 50° C.;

[0022] b2) 20 to 39.45% by weight of at least one monomer Mb2, based on the total weight of the monomers M, chosen from nonionic monoethylenically unsaturated monomers having a solubility in deionized water at 25° C. and 1 bar of up to 60 g / L and whose homopolymers have a glass transition temperature Tg of up to 40° C.;

[0023] c) 0.05 to 2.0% by weight of at least one crosslinking monomer Mc;

[0024] The aqueous emulsion polymerization is carried out at least partly in the presence of a chain transfer compound.

[0025] Thus, a first aspect of the present invention relates to an aqueous polymer dispersion obtainable by free-radical aqueous emulsion polymerization of ethylenically unsaturated monomers M as defined herein, wherein the aqueous emulsion polymerization is carried out at least partly in the presence of a chain transfer compound.

[0026] A second aspect of the present invention is a process for preparing an aqueous polymer dispersion, said process comprising the free-radical aqueous emulsion polymerization of monomers M as defined herein, wherein the aqueous emulsion polymerization is carried out at least partly in the presence of a chain transfer compound.

[0027] A further aspect of the invention relates to the use of an aqueous polymer dispersion as defined herein as a binder or co-binder in aqueous coating compositions, in particular in architectural coating compositions and in coating compositions for shaped mineral articles.

[0028] The present invention also relates to an aqueous coating composition comprising the aqueous polymer dispersion as described herein.

[0029] A further aspect of the invention relates to a method of producing a permanent coating on a surface, the method comprising applying an aqueous coating composition according to the invention to the surface and allowing the composition to dry to produce the coating.

[0030] The aqueous polymer dispersions described herein offer several advantages, in particular

[0031] - low water absorption of the coating, which is significantly lower than coatings containing binders according to the prior art;

[0032] - High mechanical strength of the coating;

[0033] -Good weather resistance;

[0034] - Good or even improved stain resistance / antifouling properties;

[0035] -Good resistance to lichen and moss growth;

[0036] -Good film-forming properties. DETAILED DESCRIPTION

[0037] Herein and throughout the specification, the term "aqueous coating composition" means a liquid aqueous coating composition containing water as a continuous phase in an amount sufficient to achieve flowability.

[0038] Here and throughout the specification, the terms "weight-%" and "weight %" are used synonymously.

[0039] Herein and throughout the specification, the indefinite article "a" includes both the singular and the plural, ie the indefinite article with respect to a component of a composition means that the component is a single compound or a plurality of compounds. If not stated otherwise, the indefinite article "a" is used synonymously with the expression "at least one".

[0040] Here and throughout the specification, the term "pphm" means parts by weight per 100 parts of monomer and corresponds to the relative amount of a certain monomer in % by weight based on the total amount of monomers M.

[0041] In this document and throughout the specification, the terms "ethoxylated" and "polyethoxylated" are used synonymously and refer to compounds having oligo- or polyoxyethylene groups formed by repeating units O-CH2CH2. In this document, the term "degree of ethoxylation" relates to the number average of repeating units O-CH2CH2 in these compounds.

[0042] Here and throughout the specification, the term "nonionic" in the context of a compound, especially a monomer, means that the corresponding compound does not carry any ionic functional groups or any functional groups which can be converted into ionic groups by protonation or deprotonation.

[0043] Herein and throughout the specification, the terms "shaped mineral article" and "shaped mineral body" are used synonymously. These terms refer to shaped articles which are essentially made of mineral material and contain a mineral binder, in particular a cementitious binder, and which are specifically described at the outset.

[0044] Herein and throughout the specification, the prefix C used in connection with a compound or a molecular moiety is n -C m Each indicates a range of possible carbon number that a molecular moiety or compound may have. n "Alkyl" refers to a group of straight-chain or branched saturated hydrocarbon radicals having 1 to n carbon atoms. The term "C n / C m "Alkyl" means a mixture of two alkyl groups, one having n carbon atoms and the other having m carbon atoms.

[0045] Herein and throughout the description, the term "ethylenically unsaturated monomers" is understood to mean monomers having at least one C=C double bond, for example 1, 2, 3 or 4 C=C double bonds, which are fully polymerizable, i.e. polymerized under the conditions of an aqueous free-radical emulsion to obtain a polymer having a carbon atom backbone. Herein and throughout the description, the term "monoethylenically unsaturated" is understood to mean monomers having a single C=C double bond, which are susceptible to free-radical polymerization under the conditions of an aqueous free-radical emulsion polymerization.

[0046] For example, the term C1-C 20Alkyl represents a group of straight or branched saturated hydrocarbon groups having 1 to 20 carbon atoms, while the term C1-C4 alkyl represents a group of straight or branched saturated hydrocarbon groups having 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-methylpropyl (isopropyl), 1,1-dimethylethyl (tert-butyl), pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, heptyl, octyl, 2-ethylhexyl, nonyl, isononyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl and in the case of nonyl, isononyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, their isomers, in particular mixtures of isomers such as "isononyl", "isodecyl". Examples of C1-C4-alkyl are, for example, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl or 1,1-dimethylethyl.

[0047] As used herein, the term "C5-C 20 "-Cycloalkyl" refers to a monocyclic or bicyclic cycloalkyl radical which is unsubstituted or substituted by 1, 2, 3 or 4 C1-C4-alkyl radicals, for example a methyl radical, wherein C5-C 20 The total number of carbon atoms in the cycloalkyl group is from 5 to 20. 20 Examples of -alkyl include, but are not limited to, cyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, cyclohexadecyl, norbornyl (=bicyclo[2.2.1]heptyl) and isobornyl (=1,7,7-trimethylbicyclo[2.2.1]heptyl).

[0048] Terminology C2-C 10-Alkylene is a divalent straight-chain or branched saturated hydrocarbon radical having 2 to 10 carbon atoms, in particular 2 to 6 or 2 to 4 carbon atoms (C2-C6-alkylene and C2-C4-alkylene), for example ethylenediyl, propylenediyl and butanediyl, wherein the radicals bonded to the C2-C4-alkylene are preferably not bonded to the C2-C6-alkylene radical. 10 -alkylene groups are bonded to the same carbon atom, for example in 1,2-ethanediyl, 1,2-propylenediyl, 1,2-butylenediyl, 2,3-butylenediyl, 2-methyl-1,2-propylenediyl, 1,3-propylenediyl, 1,4-butylenediyl, 1,3-butylenediyl, 2-methyl-1,3-propylenediyl, 1,5-pentanediyl, 1,5-hexanediyl, etc.

[0049] As used herein, the term "phenylene" refers to a divalent phenyl group, such as 1,2-phenylene and 1,4-phenylene. C1-C4-alkylphenylene refers to a phenylene group in which the benzene ring is substituted by an alkyl group.

[0050] As used herein, the term "phenyl-C2-C4-alkylene" refers to a C2-C4-alkylene group as defined herein, wherein one hydrogen atom has been replaced by a phenyl group.

[0051] According to the present invention, the monomer M comprises a combination of at least one monomer Ma1, at least one monomer Ma2 and at least one monomer Ma3:

[0052] The monomer Ma1 is preferably selected from monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, for example acrylic acid, methacrylic acid, crotonic acid, 2-ethylacrylic acid, 2-propylacrylic acid, 2-acryloyloxyacetic acid and 2-methacryloyloxyacetic acid. Acrylic acid and methacrylic acid are particularly preferred. In particular, the monomer Ma1 comprises acrylic acid. Preferably, the amount of acrylic acid is at least 50% by weight, in particular at least 70% by weight, based on the total amount of the monomer Ma1. In particular, the monomer Ma1 is selected from acrylic acid and a combination thereof with methacrylic acid, wherein the amount of acrylic acid in the combination is preferably at least 50% by weight, in particular at least 70% by weight, based on the total amount of the monomer Ma1.

[0053] The total amount of the monomers Ma1 is preferably 0.15 to 2.0% by weight, in particular 0.2 to 1.5% by weight, in particular 0.2 to 1.0% by weight, based on the total amount of the monomers M.

[0054] The monomer Ma2 is preferably selected from monoethylenically unsaturated dicarboxylic acids having 4 to 6 carbon atoms, such as itaconic acid, mesaconic acid, citraconic acid and fumaric acid. Itaconic acid, mesaconic acid and citraconic acid are preferred. In particular, the monomer Ma2 comprises itaconic acid. Preferably, the amount of itaconic acid is at least 50% by weight, in particular at least 70% by weight, based on the total amount of monomer Ma2. In particular, itaconic acid is the only monomer Ma2.

[0055] The total amount of monomers Ma2 is preferably 0.2 to 3.0% by weight, in particular 0.4 to 2.0% by weight, in particular 0.5 to 1.5% by weight, based on the total amount of monomers M.

[0056] The monomer Ma3 is selected from monoethylenically unsaturated sulfonic acids having 2 to 10 carbon atoms, in particular 2 to 8 carbon atoms, such as vinylsulfonic acid, allylsulfonic acid, styrenesulfonic acid and monomers of the general formula (I)

[0057]

[0058] in

[0059] X is NH or O,

[0060] R 11 is hydrogen or methyl,

[0061] R 12 is selected from C2-C6-alkylene, phenylene, phenyl-C1-C2-alkylene and C1-C2-alkylphenylene, wherein R 12 In particular, selected from C2-C6-alkylene,

[0062] and salts thereof, preferably ammonium salts, sodium salts, potassium salts, magnesium salts and / or calcium salts thereof, in particular sodium salts or potassium salts thereof. In formula (I), X is preferably NH. In formula (I), R 12 Preferred are C2-C6-alkylene, for example 1,2-ethylene, 1,3-propylene, 1,2-propylene, 1-methyl-1,2-propylene, 1,4-butylene, 1,3-butylene and the like.

[0063] In particular, the monomer Ma3 is selected from the monomers of formula (I) and salts thereof, preferably ammonium, sodium, potassium, magnesium and / or calcium salts thereof, in particular sodium or potassium salts thereof. Examples of monomers of formula (I) include 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidobutanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid, 2-acrylamido-2,2,4-trimethylpentanesulfonic acid, 2-methacrylamidobutanesulfonic acid, 3-methacrylamido-3-methylbutanesulfonic acid, 2-methacrylamido-2,4,4-trimethylpentanesulfonic acid, 2-sulfoethyl acrylate, 3-propanesulfoacrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl methacrylate and salts thereof, in particular ammonium, sodium, potassium, magnesium and / or calcium salts thereof, in particular sodium or potassium salts thereof.

[0064] In particular, monomer Ma3 is 2-acrylamido-2-propanesulfonic acid (AMPS) and / or a salt thereof, in particular 2-acrylamido-2-propanesulfonic acid sodium salt (AMPS-Na) or a mixture consisting of at least 50% by weight, in particular at least 70% by weight, of AMPS and / or at least one salt thereof, based on the total amount of monomer Ma3 and at least one further monomer Ma3 as defined herein.

[0065] The total amount of monomers Ma3, calculated in the form of sulfonic acid, is preferably 0.15 to 2.0% by weight, in particular 0.3 to 1.2% by weight, in particular 0.4 to 1.0% by weight, based on the total amount of monomers M.

[0066] The total amount of the combination of monomers Ma1, Ma2 and Ma3 is 0.5 to 7.0 wt %, specifically 0.7 to 4.0 wt %, specifically 1.1 to 3.0 wt %, based on the total amount of monomers M, based on the total weight of monomers M.

[0067] Preferably, the monomers M comprise from 0.7 to 4.0% by weight of the following, based on the total amount of monomers M:

[0068] a1) 0.2 to 1.5% by weight of at least one monomer Ma1, based on the total amount of the monomers M;

[0069] a2) 0.4 to 2.0% by weight of at least one monomer Ma2, based on the total amount of the monomers M;

[0070] a3) 0.3 to 1.2% by weight of at least one monomer Ma3, based on the total amount of monomers M and calculated as sulfonic acid form.

[0071] In particular, the monomers M contain 1.1 to 3.0% by weight of the following substances, based on the total amount of the monomers M:

[0072] a1) 0.2 to 1.0% by weight of at least one monomer Ma1, based on the total amount of the monomers M;

[0073] a2) 0.5 to 1.5% by weight of at least one monomer Ma2, based on the total amount of the monomers M;

[0074] a3) 0.4 to 1.0% by weight of at least one monomer Ma3, based on the total amount of monomers M and calculated as sulfonic acid form.

[0075] More preferably, the monomers M contain 0.5 to 7.0 wt. % of the following substances, based on the total amount of monomers M:

[0076] a1) 0.15 to 2.0% by weight of at least one monomer Ma1 selected from acrylic acid and mixtures thereof with methacrylic acid, based on the total amount of the monomers M;

[0077] a2) 0.3 to 3.0% by weight of at least one monomer Ma2 which comprises or is itaconic acid, based on the total amount of the monomers M;

[0078] a3) 0.2 to 1.5% by weight of at least one monomer Ma3 which comprises or is 2-acrylamidopropyl-2-methylpropanesulfonic acid or a salt thereof, based on the total amount of monomers M and calculated as sulfonic acid.

[0079] Even more preferably, the monomers M comprise from 0.7 to 4.0 wt. % of the following substances, based on the total amount of monomers M:

[0080] a1) 0.2 to 1.5% by weight of at least one monomer Ma1 selected from acrylic acid and mixtures thereof with methacrylic acid, based on the total amount of the monomers M;

[0081] a2) 0.4 to 2.0% by weight of at least one monomer Ma2 which comprises or is itaconic acid, based on the total amount of the monomers M;

[0082] a3) 0.3 to 1.2% by weight of at least one monomer Ma3 which comprises or is 2-acrylamidopropyl-2-methylpropanesulfonic acid or a salt thereof, based on the total amount of monomers M and calculated as sulfonic acid.

[0083] In particular, the monomers M contain 1.1 to 3.0% by weight of the following substances, based on the total amount of the monomers M:

[0084] a1) 0.2 to 1.0% by weight of at least one monomer Ma1, based on the total amount of the monomers M;

[0085] a2) 0.5 to 1.5% by weight of at least one monomer Ma2 which comprises or is itaconic acid, based on the total amount of the monomers M;

[0086] a3) 0.4 to 1.0% by weight of at least one monomer Ma3 which comprises or is 2-acrylamidopropyl-2-methylpropanesulfonic acid or a salt thereof, based on the total amount of monomers M and calculated as sulfonic acid.

[0087] The monomers M also comprise at least one monomer Mb1 as defined above, which is nonionic, sparingly soluble in water, i.e. its solubility in deionized water at 25° C. and 1 bar is at most 60 g / L, for example 0.1 to 60 g / L, and is characterized in that its homopolymer has a glass transition temperature Tg of at least 50° C., in particular 55 to 200° C., in particular 60 to 180° C.

[0088] The total amount of the monomers Mb1 is preferably 60.5 to 74.25% by weight, in particular 61 to 70.82% by weight, based on the total amount of the monomers M.

[0089] The monomers M also comprise at least one monomer Mb2 as defined above, which is non-ionic, sparingly soluble in water, i.e. its solubility in deionized water at 25° C. and 1 bar is at most 60 g / L, for example from 0.1 to 60 g / L, and is characterized in that its homopolymer has a glass transition temperature Tg of at most 40° C., in particular from -80 to +40° C.

[0090] The total amount of monomers Mb2, based on the total amount of monomers M, is preferably 25 to 38.75% by weight, in particular 28 to 37.82% by weight.

[0091] The actual Tg values ​​of the homopolymers of the monomers Mb1 and Mb2 are known and listed, for example, in Ullmann's der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 5th edition, volume A21, page 169, Verlag Chemie, Weinheim, 1992. Other sources for the glass transition temperature of homopolymers are, for example, J. Brandrup, EH Immergut, Polymer Handbook, 1st edition, J. Wiley, New York 1966, 2nd edition, J. Wiley, New York 1975, 3rd edition, J. Wiley, New York 1989 and 4th edition, J. Wiley, New York 2004. They can also be determined experimentally by the differential scanning calorimetry (DSC) method according to ISO 11357-2:2013, preferably with sample preparation according to ISO 16805:2003.

[0092] Suitable monomers Mb1 are monovinylaromatic monomers, for example styrene, C1-C2-alkyl methacrylates, for example methyl methacrylate and ethyl methacrylate, tert-butyl methacrylate, tert-butyl acrylate and mixtures thereof. In particular, the monomers Mb1 comprise at least one C1-C2-alkyl methacrylate and tert-butyl acrylate. In particular, the monomers Mb1 comprise methyl methacrylate. In particular, the monomers Mb1 are selected from methyl methacrylate and combinations thereof with styrene or tert-butyl acrylate, wherein the amount of methyl methacrylate in the combination is preferably at least 50% by weight, in particular at least 70% by weight, based on the total amount of monomers Mb1. However, styrene can also be the only monomer Mb1.

[0093] Suitable monomers Mb2 are C1-C1 monomers of acrylic acid other than tert-butyl acrylate. 20 -alkyl esters, acrylic acid, C5-C 20-cycloalkyl esters, C3-alkyl methacrylates, n-butyl methacrylate, C5-C 20 -alkyl esters, C5-C 20 - Cycloalkyl esters and mixtures thereof.

[0094] Suitable acrylic acid C1-C 20 -Alkyl esters include, but are not limited to, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, isodecyl acrylate, 2-propylheptyl acrylate, dodecyl acrylate, C acrylate 12 / C 14 -Alkyl esters, acrylic acid C 12 -C 15 -alkyl esters, isotridecyl acrylate, acrylic acid C 16 / C 18 -alkyl acrylate and octadecyl acrylate.

[0095] Suitable acrylic acid C5-C 20 - Cycloalkyl esters include, but are not limited to, cyclohexyl acrylate, norbornyl acrylate, and isobornyl acrylate.

[0096] Suitable C3-alkyl methacrylates and C5-C 20 - Alkyl esters include, but are not limited to, n-propyl methacrylate, isopropyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, n-decyl methacrylate, 2-propylheptyl methacrylate, dodecyl methacrylate, C methacrylate 12 / C 14 -Alkyl esters, methacrylate C 12 -C 15 -alkyl esters, isotridecyl methacrylate, C methacrylate 16 / C 18 -alkyl esters and octadecyl methacrylate.

[0097] Suitable C5-C methacrylic acid 16 - Cycloalkyl esters include, but are not limited to, cyclohexyl methacrylate, norbornyl methacrylate, and isobornyl methacrylate.

[0098] Preferably, monomer Mb2 is a C2-C 10 -alkyl esters, except tert-butyl acrylate and n-butyl methacrylate, of which the C2-C 10The alkyl esters are in particular selected from ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate and mixtures thereof, for example a mixture of n-butyl acrylate and 2-ethylhexyl acrylate, a mixture of n-butyl acrylate and ethyl acrylate, a mixture of n-butyl acrylate and n-butyl methacrylate, a mixture of n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate and a mixture of ethyl acrylate, n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate.

[0099] The monomer M also contains at least one crosslinking monomer Mc. Suitable crosslinking monomers are ethylenically unsaturated monomers (hereinafter referred to as monomer Mc1) having at least one functional group capable of reacting with itself or with other functional groups in a polymer formed by polymerization of the monomer M. Suitable crosslinking monomers are in particular multiethylenically unsaturated monomers having at least two, in particular 2 to 6, non-conjugated ethylenically unsaturated double bonds, hereinafter referred to as monomer Mc2. Suitable monomers are also monoethylenically unsaturated monomers having at least one other functional group capable of reacting with itself or with a carboxylic acid group (hereinafter referred to as monomer Mc2), as well as mixtures of different monomers Mc. Monomer Mc may also be a combination of 2 or more different monomers Mc, for example a combination of at least one monomer Mc1 and at least one monomer Mc2.

[0100] The total amount of the monomers Mc is preferably 0.05 to 1.5% by weight, in particular 0.08 to 1.0% by weight, based on the total amount of the monomers M.

[0101] The reactive groups of the monomer Mc1 may be, for example, oxirane groups, such as glycidyl groups, or silyl groups with at least one Si-bonded alkoxy group, including, for example, alkyldialkoxysilyl groups, such as methyldimethoxysilyl, ethyldimethoxysilyl, methyldiethoxysilyl and ethyldiethoxysilyl, and trialkoxysilyl groups, such as trimethoxysilyl and triethoxysilyl. In the context of silyl groups, the term alkyl refers in particular to alkyl groups having 1 to 4 carbon atoms. The term alkoxy refers to alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, propoxy and butoxy.

[0102] Examples of monomer Mc1 include but are not limited to

[0103] - glycidyl esters of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms (hereinafter referred to as monomers Mc1.1), in particular glycidyl acrylate and glycidyl methacrylate;

[0104] - Monoethylenically unsaturated monomers carrying at least one trialkoxysilyl group or at least one alkyldialkoxysilyl group, hereinafter referred to as monomers Mc1.2. Examples of these monomers Mc1.2 include vinyltrialkoxysilanes, such as vinyltrimethoxysilane, alkylvinyldialkoxysilanes, such as methylvinyldialkoxysilane. Examples of these monomers Mc1.2 also include alkyldialkoxysilylalkyl esters of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, in particular alkyldialkoxysilylalkyl esters of acrylic acid and alkyldialkoxysilylalkyl esters of methacrylic acid, such as (meth)acryloxypropyl-methyldimethoxysilane and (meth)acryloxypropyl-methyldiethoxysilane, and trialkoxysilylalkyl esters of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, in particular trialkoxysilylalkyl esters of acrylic acid and trialkoxysilylalkyl esters of methacrylic acid, such as (meth)acryloxypropyl-trimethoxysilane and (meth)acryloxypropyl-triethoxysilane, and mixtures thereof.

[0105] Among the monomers Mc1, preference is given to monomers Mc1.2 and combinations of at least one monomer Mc1.2 with one or more monomers Mc1.1.

[0106] Among the monomers Mc1.2, trialkoxysilylalkyl esters of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms are preferred, in particular trialkoxysilylalkyl esters of acrylic acid and trialkoxysilylalkyl esters of methacrylic acid, for example (meth)acryloxypropyl-trimethoxysilane and (meth)acryloxypropyl-triethoxysilane and mixtures thereof.

[0107] Examples of suitable monomers Mc2 include

[0108] Polyacrylates, polymethacrylates, polyallyl ethers or polyvinyl ethers of polyols having at least 2 OH groups, for example 2 to 6 OH groups, hereinafter referred to as monomers Mc2.1. The OH groups of the polyols may be completely or partially etherified or esterified, provided that they have on average at least 2, for example 2 to 6, ethylenically unsaturated double bonds. Examples of the polyol component in this crosslinking agent Mc2.1 include, but are not limited to, diols such as 1,2-ethanediol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, but-2-ene-1,4-diol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, neopentyl glycol, 3-methylpentane-1,5-diol, 2,5-dimethyl-1,3-hexanediol, 2,2,4-trimethylol-1, Methyl-1,3-pentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,4-bis(hydroxymethyl)cyclohexane, hydroxypivalic acid neopentyl glycol monoester, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis[4-(2-hydroxypropyl)-phenyl]propane, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 3-thiopentane-1,5-diol, and also polyethylene glycol, polypropylene glycol, block copolymers of ethylene oxide or propylene oxide, random copolymers of ethylene oxide and propylene oxide and polytetrahydrofuran, in each case having a molecular weight of 200 to 10 000. Examples of polyols having more than two OH groups are trimethylolpropane, glycerol, pentaerythritol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, cyanuric acid, sorbitan, sugars such as sucrose, glucose and mannose. The polyol component having more than two OH groups in this crosslinker Mc2.1 can be alkoxylated with ethylene oxide or propylene oxide;

[0109] - monoesters of monoethylenically unsaturated C3-C6 monocarboxylic acids, in particular acrylic acid or methacrylic acid, with monoethylenically unsaturated aliphatic or alicyclic monohydroxy compounds, hereinafter referred to as monomers Mc2.2. Examples include vinyl acrylate, vinyl methacrylate, allyl acrylate, allyl methacrylate, cyclohex-2-enyl acrylate, cyclohex-2-enyl methacrylate, norbornene acrylate and norbornene methacrylate;

[0110] - straight-chain or branched, linear or cyclic, aliphatic or aromatic hydrocarbons having at least two double bonds and, in the case of aliphatic hydrocarbons, not being conjugated, hereinafter referred to as monomers Mc2.3. Examples include divinylbenzene, divinyltoluene, 1,7-octadiene, 1,9-decadiene, 4-vinyl-1-cyclohexene, trivinylcyclohexane or polybutadienes having a molecular weight of 200 to 20 000, in particular divinylaromatic compounds, for example 1,3-divinylbenzene, 1,4-divinylbenzene.

[0111] Among the monomers Mc2, preference is given to monomers Mc2.2, in particular acrylates and methacrylates, especially allyl acrylate and allyl methacrylate.

[0112] In a specific group of embodiments, the monomer Mc comprises at least one monomer Mc1.2, which is particularly selected from monoethylenically unsaturated monomers having at least one trialkoxysilyl group, in particular trialkoxysilylalkyl esters of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, and which is more particularly selected from trialkoxysilylalkyl esters of acrylic acid and trialkoxysilylalkyl esters of methacrylic acid, for example (meth)acryloxypropyl-trimethoxysilane and (meth)acryloxypropyl-triethoxysilane and mixtures thereof.

[0113] In this specific set of embodiments, monomer Mc1.2 may be the only monomer Mc. In this specific set of embodiments, monomer Mc may also be a combination of at least one monomer Mc1.2 and at least one monomer Mc different from monomer Mc1.2, such as monomer Mc1.1 or monomer Mc2, in particular monomer Mc2.2. Among the combinations of at least one monomer Mc1.2 and at least one monomer Mc different from monomer Mc1.2, a combination of at least one monomer Mc1.2 and at least one monomer Mc1.1 preferably selected from glycidyl acrylate and glycidyl methacrylate is particularly preferred, and a combination of at least one monomer Mc1.2 and at least one monomer Mc2.2 preferably selected from allyl acrylate and allyl methacrylate is preferred.

[0114] In a preferred first group of embodiments, monomer M comprises

[0115] a) 0.7 to 4.0 wt. % of a combination of acidic monomers, based on the total amount of monomers M, comprising

[0116] a1) 0.2 to 1.5% by weight of at least one monomer Ma1, in particular at least one preferred monomer Ma1, based on the total amount of the monomers M;

[0117] a2) 0.4 to 2.0% by weight of at least one monomer Ma2, in particular at least one preferred monomer Ma2, based on the total amount of the monomers M;

[0118] a3) 0.3 to 1.2% by weight of at least one monomer Ma3, in particular at least one preferred monomer Ma3, based on the total amount of monomers M and calculated in the sulfonic acid form;

[0119] b1) 60.5 to 74.25% by weight of at least one monomer Mb1, in particular at least one preferred monomer Mb1, based on the total amount of the monomers M;

[0120] b2) 25 to 38.75% by weight of at least one monomer Mb2, in particular at least one preferred monomer Mb2, based on the total amount of the monomers M;

[0121] c) 0.05 to 1.5% by weight of at least one monomer Mc, in particular at least one preferred monomer Mc, more preferably at least one monomer Mc1.2 or a combination of at least one monomer Mc1.2 and at least one monomer Mc1.1 and / or at least one monomer Mc2.2, based on the total amount of monomers M.

[0122] In a particularly preferred second group of embodiments, monomer M comprises

[0123] a) 1.1 to 3.0 wt. % of a combination of acidic monomers, based on the total amount of monomers M, comprising

[0124] a1) 0.2 to 1.0% by weight of at least one monomer Ma1, in particular at least one preferred monomer Ma1, based on the total amount of the monomers M;

[0125] a2) 0.5 to 1.5% by weight of at least one monomer Ma2, in particular at least one preferred monomer Ma2, based on the total amount of the monomers M;

[0126] a3) 0.4 to 1.0% by weight of at least one monomer Ma3, in particular at least one preferred monomer Ma3, based on the total amount of monomers M and calculated in the sulfonic acid form;

[0127] b1) 61 to 70.82% by weight of at least one monomer Mb1, in particular at least one preferred monomer Mb1, based on the total amount of the monomers M;

[0128] b2) 28 to 37.82% by weight of at least one monomer Mb2, in particular at least one preferred monomer Mb2, based on the total amount of the monomers M;

[0129] c) 0.08 to 1.0% by weight of at least one monomer Mc, in particular at least one preferred monomer Mc, more preferably at least one monomer Mc1.2 or a combination of at least one monomer Mc1.2 and at least one monomer Mc1.1 and / or at least one monomer Mc2.2, based on the total amount of monomer M.

[0130] In a very preferred third group of embodiments, the monomers M comprise a) 0.5 to 7.0 wt. % of a combination of acidic monomers, based on the total amount of monomers M, comprising

[0131] a1) 0.15 to 2.0% by weight of at least one monomer Ma1 selected from acrylic acid and mixtures thereof with methacrylic acid, based on the total amount of the monomers M;

[0132] a2) 0.2 to 3.0% by weight, based on the total amount of monomers M, of at least one monomer Ma2 which comprises or is itaconic acid;

[0133] a3) 0.15 to 2.0% by weight of at least one monomer Ma3 which comprises or is 2-acrylamidopropyl-2-methylpropanesulfonic acid or a salt thereof, based on the total amount of monomers M and calculated as the sulfonic acid form;

[0134] b1) 60 to 79.45% by weight of at least one monomer Mb1, in particular at least one preferred monomer Mb1, based on the total amount of the monomers M;

[0135] b2) 20 to 39.25% by weight of at least one monomer Mb2, based on the total amount of the monomers M, selected from the group consisting of C2-C 10 -alkyl esters and n-butyl methacrylate, wherein the C2-C 10 the alkyl esters are in particular selected from ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate and mixtures thereof, for example a mixture of n-butyl acrylate and 2-ethylhexyl acrylate, a mixture of n-butyl acrylate and ethyl acrylate, a mixture of n-butyl acrylate and n-butyl methacrylate, a mixture of n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate and a mixture of ethyl acrylate, n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate;

[0136] c) 0.05 to 2.0% by weight of at least one monomer Mc, in particular at least one preferred monomer Mc, more preferably at least one monomer Mc1.2 or a combination of at least one monomer Mc1.2 and at least one monomer Mc1.1 and / or at least one monomer Mc2.2, based on the total amount of monomer M.

[0137] In an even more preferred fourth group of embodiments, monomer M comprises

[0138] a) 0.7 to 4.0 wt. % of a combination of acidic monomers, based on the total amount of monomers M, comprising

[0139] a1) 0.2 to 1.5% by weight of at least one monomer Ma1 selected from acrylic acid and mixtures thereof with methacrylic acid, based on the total amount of the monomers M;

[0140] a2) 0.4 to 2.0% by weight, based on the total amount of monomers M, of at least one monomer Ma2 which comprises or is itaconic acid;

[0141] a3) 0.3 to 1.2% by weight of at least one monomer Ma3 which comprises or is 2-acrylamidopropyl-2-methylpropanesulfonic acid or a salt thereof, based on the total amount of monomers M and calculated as the sulfonic acid form;

[0142] b1) 60.5 to 74.25% by weight of at least one monomer Mb1, in particular at least one preferred monomer Mb1, based on the total amount of the monomers M;

[0143] b2) 25 to 38.75% by weight of at least one monomer Mb2, based on the total amount of the monomers M, selected from the C2-C 10 -alkyl esters, except tert-butyl acrylate and n-butyl methacrylate, of which the C2-C 10 the alkyl esters are in particular selected from ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate and mixtures thereof, for example a mixture of n-butyl acrylate and 2-ethylhexyl acrylate, a mixture of n-butyl acrylate and ethyl acrylate, a mixture of n-butyl acrylate and n-butyl methacrylate, a mixture of n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate and a mixture of ethyl acrylate, n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate;

[0144] c) 0.05 to 1.5% by weight of at least one monomer Mc, in particular at least one preferred monomer Mc, more preferably at least one monomer Mc1.2 or a combination of at least one monomer Mc1.2 and at least one monomer Mc1.1 and / or at least one monomer Mc2.2, based on the total amount of monomers M.

[0145] In a particularly preferred fifth group of embodiments, monomer M comprises

[0146] a) 1.1 to 3.0 wt. % of a combination of acidic monomers, based on the total amount of monomers M, comprising

[0147] a1) 0.2 to 1.0% by weight of at least one monomer Ma1 selected from acrylic acid and mixtures thereof with methacrylic acid, based on the total amount of the monomers M;

[0148] a2) 0.5 to 1.5% by weight, based on the total amount of monomers M, of at least one monomer Ma2 which comprises or is itaconic acid;

[0149] a3) 0.4 to 1.0% by weight of at least one monomer Ma3 which comprises or is 2-acrylamidopropyl-2-methylpropanesulfonic acid or a salt thereof, based on the total amount of monomers M and calculated as the sulfonic acid form;

[0150] b1) 61 to 70.82% by weight, based on the total amount of the monomers M, of at least one monomer Mb1 which comprises or is methyl methacrylate;

[0151] b2) 28 to 37.82% by weight of at least one monomer Mb2, based on the total amount of monomers M, selected from the C2-C 10 -alkyl esters, except tert-butyl acrylate and n-butyl methacrylate, of which the C2-C 10 the alkyl esters are in particular selected from ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate and mixtures thereof, for example a mixture of n-butyl acrylate and 2-ethylhexyl acrylate, a mixture of n-butyl acrylate and ethyl acrylate, a mixture of n-butyl acrylate and n-butyl methacrylate, a mixture of n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate and a mixture of ethyl acrylate, n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate;

[0152] c) 0.08 to 1.0% by weight of at least one monomer Mc, in particular at least one preferred monomer Mc, more preferably at least one monomer Mc1.2 or a combination of at least one monomer Mc1.2 and at least one monomer Mc1.1 and / or at least one monomer Mc2.2, based on the total amount of monomer M.

[0153] In the above-mentioned groups 1 to 5 of embodiments, the monomer Mc1.2 is preferably selected from trialkoxysilylalkyl acrylates and trialkoxysilylalkyl methacrylates, such as (meth)acryloxypropyl-trimethoxysilane and (meth)acryloxypropyl-triethoxysilane and mixtures thereof.

[0154] In the above-mentioned groups 1 to 5 of embodiments, the monomer Mc1.1 is preferably selected from glycidyl acrylate and glycidyl methacrylate.

[0155] In the above-mentioned embodiments of groups 1 to 5, the monomer Mc2.2 is preferably selected from vinyl acrylate, vinyl methacrylate, allyl acrylate, allyl methacrylate, cyclohex-2-enyl acrylate, cyclohex-2-enyl methacrylate, norbornene acrylate and norbornene methacrylate and is particularly selected from allyl acrylate and allyl methacrylate.

[0156] Typically, the total weight of the monomers Ma1, Ma2, Ma3, Mb1, Mb2 and Mc is at least 95% by weight, in particular at least 98% by weight, in particular at least 99% by weight or 100% by weight, based on the total amount of monomers M. A person skilled in the art will immediately appreciate that the weight data given for the monomers Ma1, Ma2, Ma3, Mb1, Mb2 and Mc do not exceed 100% by weight.

[0157] Optionally, the monomers M also comprise at least one nonionic monoethylenically unsaturated monomer Md which is different from the above-mentioned monomers Mb1, Mb2 and Mc and which preferably has a functional group selected from the group consisting of carboxamide groups, hydroxyl groups, urea groups and keto groups.

[0158] Examples of monomers Md having a carboxamide group are

[0159] - primary amides of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, for example acrylamide and methacrylamide;

[0160] - an N-C1-C1-C1-hydroxy-1-nitro-2-nitro-2-nitrocarboxylic acid having 3 to 6 carbon atoms 10 Alkylamides, especially acrylic or methacrylic acid N-C1-C 10 Alkylamides, such as N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-isopropylacrylamide, N-butylacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, N-isopropylmethacrylamide and N-butylmethacrylamide.

[0161] Examples of monomers Md having hydroxyl groups are hydroxy-C2-C4-alkyl esters of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, in particular acrylic acid or methacrylic acid, for example 2-hydroxyethyl acrylate, 2- or 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2- or 3-hydroxypropyl methacrylate and 4-hydroxybutyl methacrylate.

[0162] Examples of the monomer Md having a urea group are 2-(2-oxoimidazolin-1-yl)ethyl acrylate, 2-(2-oxoimidazolin-1-yl)ethyl methacrylate, which are also referred to as 2-ureido(meth)acrylate, N-(2-acryloyloxyethyl)urea, N-(2-methacryloyloxyethyl)urea, N-(2-(2-oxoimidazolin-1-yl)ethyl)acrylamide, N-(2-(2-oxoimidazolin-1-yl)ethyl)methacrylamide, 1-allyl-2-oxoimidazolin and N-vinyl urea.

[0163] Examples of the monomer Md having a keto group are acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, acetoacetoxybutyl methacrylate, 2-(acetoacetoxy)ethyl methacrylate, diacetone acrylamide (DAAM), diacetone acrylamide, and diacetone methacrylamide.

[0164] Typically, the amount of monomers Md does not exceed 5% by weight, in particular 2% by weight, in particular 1% by weight, based on the total amount of monomers M. In particular, the monomers M do not contain monomers other than monomers Ma1, Ma2, Ma3, Mb1, Mb2 and Mc.

[0165] According to the invention, the aqueous polymer dispersion is prepared in the presence of at least one chain transfer compound.

[0166] In general, chain transfer compounds are understood to mean compounds which transfer free radicals, thereby preventing the growth of polymer chains or controlling the chain growth in polymerization and thus reducing the molecular weight of the resulting polymer. In general, chain transfer compounds have at least one readily abstractable hydrogen atom. Preferably, the abstractable hydrogen is part of a thiol group, i.e. a group SH, also called a "thiol group".

[0167] The chain transfer compounds are especially selected from:

[0168] -SH-substituted C2-C6 alkanoic acid (hereinafter referred to as C2-C6 thioalkanoic acid) 20 -alkyl esters (chain transfer compounds T.1), in particular C1-C2-alkyl esters of mercaptoacetic acid (=thioglycolic acid) 20 -alkyl esters, such as methyl thioglycolate, ethyl thioglycolate, n-butyl thioglycolate, n-hexyl thioglycolate, n-octyl thioglycolate, 2-ethylhexyl thioglycolate and n-decyl thioglycolate and C1-C2 thioglycolate of mercaptopropionic acid 20 - alkyl esters, for example methyl mercaptopropionate, ethyl mercaptopropionate, n-butyl mercaptopropionate, n-hexyl mercaptopropionate, n-octyl mercaptopropionate, 2-ethylhexyl mercaptopropionate and n-decyl mercaptopropionate;

[0169] -C1-C 20 - alkyl mercaptans (chain transfer compounds T.2), in particular C6-C 16- alkyl mercaptans, for example ethanethiol, n-propyl mercaptan, 2-propyl mercaptan, n-butyl mercaptan, 2-butyl mercaptan, 2-methyl-2-propyl mercaptan, n-pentyl mercaptan, 2-pentyl mercaptan, 3-pentyl mercaptan, 2-methyl-2-butyl mercaptan, 3-methyl-2-butyl mercaptan, n-hexyl mercaptan, 2-hexyl mercaptan, 3-hexyl mercaptan, 2-methyl-2-pentyl mercaptan, 3-methyl-2-pentyl mercaptan, 4-methyl-2-pentyl mercaptan, 2-methyl-3-pentyl mercaptan, 3-methyl-3-pentyl mercaptan, 2-ethylbutyl mercaptan, 2-ethyl-2-butyl mercaptan, n-heptyl mercaptan and its isomeric compounds, n-octyl mercaptan and its isomeric compounds, n-nonyl mercaptan and its isomeric compounds, n-decyl mercaptan and its isomeric compounds, n-undecar mercaptan and its isomeric compounds, n-dodecyl mercaptan and its isomeric compounds, for example tert-dodecyl mercaptan, n-tridecar mercaptan and its isomeric compounds;

[0170] -OH-substituted C2-C 20 - alkyl mercaptans (chain transfer compounds T.3), for example 2-hydroxyethanethiol and 2-hydroxypropanethiol;

[0171] - aromatic mercaptans (chain transfer compounds T.4), for example benzenethiol, o-, m- or p-methylbenzenethiol,

[0172] - and mixtures thereof.

[0173] Examples of further chain transfer compounds which can be used instead of or in combination with the chain transfer compounds T.1 to T.4 are aliphatic and / or araliphatic halogen compounds, for example n-butyl chloride, n-butyl bromide, n-butyl iodide, dichloromethane, dichloroethane, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, carbon tetrabromide, benzyl chloride, benzyl bromide, and also aliphatic and / or aromatic aldehydes, for example acetaldehyde, propionaldehyde and / or benzaldehyde, hydrocarbons with readily abstractable hydrogen atoms, for example toluene and mercaptan compounds different from T.1 to T.4, for example the mercaptan compounds described in Polymer Handbook, 3rd edition, 1989, J. Brandrup and EH Immergut, John Wiley & Sons, Part II, pages 133 to 141.

[0174] Particular preference is given to chain transfer compounds T.1 and T2, in particular C4-C4 substituted C2-C4 alkanoic acids. 16 -alkyl esters, especially C4-C 16 -alkyl esters, C4-C 16 -alkyl esters, C6-C 16 - Alkyl mercaptans and mixtures thereof.

[0175] The amount of chain transfer compounds is preferably 0.05 to 1.2% by weight, in particular 0.1 to 0.9% by weight, in particular 0.15 to 0.6% by weight, based on the total weight of the monomers M.

[0176] Typically, the glass transition temperature T of the polymer in the aqueous polymer dispersion of the invention formed from the polymerized monomers M is g 25 to 70°C, in particular 28 to 50°C, in particular 30 to 45°C. In the case of multistage polymers comprising two or more polymers or polymer phases, respectively, having different glass transition temperatures, the glass transition temperatures of the individual polymer phases may be outside the ranges given herein. However, the weight average glass transition temperature T calculated by the following formula g (av)

[0177] T g (av)=(T g (1)*w1+Tg(2)*w2....Tg(n)*w n )

[0178] is 25 to 70°C, particularly 28 to 50°C, particularly 30 to 45°C. In the equation, T g (1) T g (2) to T g (n) represents the individual glass transition temperature (in °C or K) of the individual polymers 1, 2 to n, and w1, w2 to w n The amounts of the individual polymers 1, 2 to n are indicated in % by weight.

[0179] The actual glass transition temperature depends on the composition of the monomers M forming the polymer in the polymer dispersion, i.e., on the type and relative amount of monomers Ma1, Ma2, Ma3, Mb1, Mb2, Mc and optional monomer Md (if present). The theoretical glass transition temperature can be calculated from the composition of the monomers M used in the emulsion polymerization. The theoretical glass transition temperature is usually calculated from the composition of the monomers by the Fox equation:

[0180] 1 / Tg(F)=x1 / Tg1+x2 / Tg2+....x n / Tg n .

[0181] In this equation, x1, x2, ....x n is the mass fraction of different monomers 1, 2, ....n, and Tg1, Tg1, ....Tg nis the actual glass transition temperature (in Kelvin) of a homopolymer synthesized from only one of the monomers 1, 2, ... n at a time. Tg(F) is the theoretical glass transition temperature according to Fox. The Fox equation has been described by TG Fox in Bull. Am. Phys. Soc. 1956, 1, p. 123 and can also be found in Ullmann's der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], Vol. 19, p. 18, 4th edition, Verlag Chemie, Weinheim, 1980. Actual Tg values ​​for homopolymers of most monomers are known and are listed in the references cited above.

[0182] Typically, the theoretical glass transition temperature Tg calculated according to Fox as described herein is t The experimentally determined glass transition temperatures described herein are similar or even identical and deviate from each other by no more than 5 K, in particular they deviate by no more than 2 K. Therefore, both the actual and theoretical glass transition temperatures of the polymers can be varied by selecting suitable monomers M1, M2 . . . M n and its mass fraction in the monomer composition x1, x1, ...x n Adjustments are made to achieve the desired glass transition temperatures Tg(1) and Tg(2), respectively. Appropriate amounts of monomers M1, M2, ... M n It is common knowledge for the skilled person to obtain copolymers and / or copolymers with the desired glass transition temperature. Thus, the monomers M are selected so as to obtain a theoretical glass transition temperature Tg(F) according to Fox of 25 to 70°C, in particular 28 to 50°C, in particular 30 to 45°C.

[0183] For the purposes of the present invention, it has been found to be advantageous if the polymer particles comprised in the polymer latex have a Z-average particle size of from 80 to 500 nm, in particular from 80 to 300 nm (determined by quasi-elastic light scattering).

[0184] If not otherwise specified, the size of the particles and the distribution of the particle sizes are determined by quasi-elastic light scattering (QELS), also known as dynamic light scattering (DLS). The measurement method is described in the ISO 13321:1996 standard. The determination can be carried out using a high-performance particle size analyzer (HPPS). For this purpose, a sample of an aqueous polymer latex is diluted and the dilution is analyzed. In the case of QELS, the polymer concentration of the aqueous dilution is 0.001 to 0.5% by weight, depending on the particle size. For most purposes, a suitable concentration is 0.01% by weight. However, higher or lower concentrations can be used to achieve an optimal signal-to-noise ratio. Measurement configuration: automated HPPS from Malvern with continuous flow cuvette and Gilson autosampler. Parameters: measurement temperature 20.0°C; measurement time 120 seconds (6 cycles of 20 seconds each); scattering angle 173°; wavelength laser 633nm (HeNe); refractive index of the medium 1.332 (water); viscosity 0.9546mPa·s. The measurement gives the average value (fitted average) of the second order cumulants analysis, i.e. the Z average. The "fitted average" is the average value of the intensity weighted hydrodynamic particle size (in nm).

[0185] The hydrodynamic particle size can also be determined by hydrodynamic chromatographic fractionation (HDC), as described, for example, in "Characterization of aqueous polymer dispersions" by H. Wiese, Polymer Dispersions and Their Industrial Applications (Wiley-VCH, 2002), pp. 41-73. For further details, reference is made to the examples and descriptions below.

[0186] The particle size distribution of the polymer particles contained in the polymer dispersion is in particular unimodal or almost unimodal, which means that the distribution function of the particle size has a single maximum. However, the particle size distribution of the copolymer particles contained in the polymer latex may also be multimodal, in particular bimodal, which means that the distribution function of the particle size has at least two maxima. Preferably, the first maximum is in the range of 50 to 180 nm and the second maximum is in the range of 200 to 400 nm.

[0187] Preferably, the final polymer dispersion has a pH of at least pH 7, such as from pH 7 to pH 12, prior to use in the coating composition.

[0188] The aqueous polymer dispersions of the invention generally have a solids content of from 30 to 75% by weight, preferably from 40 to 65% by weight, in particular from 45 to 60% by weight.

[0189] Polymer dispersions can be formulated with film-forming aids (also called filming aids). It is well known that film-forming aids reduce the minimum film-forming temperature of polymer dispersions. The minimum film-forming temperature (hereinafter referred to as MFFT) is the lowest temperature at which the polymer particles of a polymer dispersion coalesce and form a cohesive film. The MFFT is usually determined by applying the polymer dispersion as a film to a metal plate with a defined temperature gradient - see DIN ISO 2115: 2001-04.

[0190] One aspect of the present invention therefore relates to a polymer dispersion as described herein comprising at least one film-forming aid.

[0191] The amount of film-forming aid is generally selected so as to give an MFFT of 0 to 15° C. Preferably, the amount of film-forming aid is 2 to 25% by weight, in particular 5 to 20% by weight, based on the total amount of polymer formed by the polymerized monomers M.

[0192] Suitable film-forming aids are solvents, also called non-permanent plasticizers and permanent plasticizers. Permanent plasticizers generally have lower solubility in water and lower volatility than non-permanent plasticizers. Non-permanent plasticizers evaporate from the coating in contrast to permanent plasticizers and serve mainly to achieve better coalescence of the binder particles at low temperatures. Suitable film-forming aids providing a non-permanent plasticizing effect are, for example,

[0193] i) hydrocarbons, such as white spirit and pine oil,

[0194] ii) C2-C4-alkanediols, also called C2-C4-alkylene glycols, di-C2-C4-alkylene glycols, tri-C2-C4-alkylene glycols and their mono-C1-C6-alkyl ethers, for example propylene glycol, ethylene glycol, butanediol, diethylene glycol, dipropylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol hexyl ether, diethylene glycol monomethyl ether, diethylene glycol monopropyl ether, dipropylene glycol methyl ether, dipropylene glycol n-butyl ether, propylene glycol tert-butyl ether, tripropylene glycol methyl ether, butanediol (=2-(2-(butoxy)ethoxy)ethanol)) and 1-methoxy-2-propanol;

[0195] iii) monoesters and diesters of C2-C8-alkanediols, di-C2-C4-alkylene glycols and tri-C2-C4-alkylene glycols with C2-C4-alkanoic acids, such as acetic acid, propionic acid, butyric acid and isobutyric acid, and monoesters of mono-C1-C6-alkyl ethers of C2-C4-alkanediols, di-C2-C4-alkylene glycols and tri-C2-C4-alkylene glycols with C2-C4-alkanoic acids, for example ethylene glycol butyl ether acetate, ethylene glycol butyl ether diacetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate and 2,2,2-trimethyl-1,3-pentanediol monoisobutyrate

[0196] iv) di-C1-C6-alkyl esters of aliphatic dicarboxylic acids having 4 to 8 carbon atoms, for example dibutyl adipate, diisobutyl adipate, diisobutyl succinate, diisobutyl glutarate, diisobutyl maleate;

[0197] v) glycol ethers and esters, for example, from BASF SE as and and commercially available under the name, and from Dow Commercially available product name.

[0198] Suitable low volatility external plasticizers include the following: dimethyl phthalate, dibutyl phthalate, dioctyl phthalate and other esters of phthalic acid, propoxylated m-cresol with a number average propoxylation degree of 6, propoxylated p-cresol with a number average propoxylation degree of 6, and mixtures of these two oligo(propylene glycol)cresol ethers, oligo(propylene glycol)cresol ethers with a number average propoxylation degree of 3, and oligo(propylene glycol)cresol ethers with a number average propoxylation degree of 12, as well as oligo(propylene glycol)phenyl ethers and oligo(propylene glycol)alkylphenyl ethers with a number average propoxylation degree of 3 to 12, aromatic glycol ethers, ethyl p-toluenesulfonate, alkyl esters of aromatic sulfonic acids, tributoxyethyl phosphate, tri-n-butyl phosphate and other phosphoric acid esters.

[0199] Preference is given to film-forming aids which are different from hydrocarbons. Preference is also given to non-permanent plasticizers. Particular preference is given to film-forming aids from groups ii) to v).

[0200] The aqueous polymer dispersions can be prepared by free-radical aqueous emulsion polymerization of the monomers M. According to the invention, the aqueous emulsion polymerization is carried out at least partly in the presence of chain transfer compounds as disclosed herein.

[0201] Since the chain transfer compound is consumed in the free-radical aqueous emulsion polymerization, the expression "at least partially" is well understood to mean that the chain transfer compound is present in the polymerization reaction mixture during at least a certain period of the polymerization, preferably at least 10% of the total duration of the polymerization. For example, the total amount of the chain transfer compound can be added to the polymerization reaction at the beginning, or it can be added in batches or in several batches or continuously during the polymerization reaction. In particular, the main amount of the chain transfer compound, i.e. at least 50% by weight, preferably at least 70% by weight of the total amount of the chain transfer compound, is added during the polymerization reaction. The addition rate of the chain transfer compound is preferably selected so that the main amount of the chain transfer compound, i.e. at least 50% by weight, preferably at least 70% by weight of the total amount of the chain transfer compound, is added continuously during the period of the polymerization reaction; at least 10% of the total polymerization reaction time.

[0202] As already mentioned, chain transfer compounds having a mercapto group are preferred, in particular the chain transfer compounds of the abovementioned groups T.1 to T.4. Particular preference is given to chain transfer compounds T.1 and T2, in particular the C4-C4 residues of SH-substituted C2-C4 alkanoic acids. 16 -alkyl esters, especially C4-C 16 -alkyl esters, C4-C 16 -alkyl esters, C6-C 16 - Alkyl mercaptans and mixtures thereof.

[0203] The amount of chain transfer compounds, based on the total weight of the monomers M, is preferably 0.05 to 1.2% by weight, in particular 0.1 to 0.9% by weight and in particular 0.15 to 0.6% by weight.

[0204] Preferably, the free radical aqueous emulsion polymerization is carried out as a free radical aqueous multistage emulsion polymerization. The free radical aqueous multistage emulsion polymerization is a free radical aqueous emulsion polymerization which is carried out in at least two consecutive polymerization steps, wherein in each step a part M' of the monomers M is polymerized in a free radical emulsion polymerization, wherein the second and any further polymerization steps are carried out in the polymer dispersion obtained in the preceding step.

[0205] In the free radical multistage emulsion polymerization, the monomer composition of the part M' polymerized in each polymerization step may be the same or different. Preferably, in one of the polymerization steps of the free radical multistage emulsion polymerization, hereinafter referred to as step (i), the relative proportion of the total amount of all acidic monomers (i.e., monomers Ma1, Ma2, and Ma3) in the part of the monomers M (hereinafter referred to as monomers M(i)) polymerized in the polymerization step (i) is higher than the relative proportion of the total amount of all acidic monomers polymerized in any other polymerization step. In particular, the relative proportion of the total amount of all acidic monomers present in the monomers M(i) - relative to the total amount of monomers M(i) - is at least 1 wt. % higher than the relative proportion of the total amount of all acidic monomers present in the monomers of the other polymerization steps. In particular, the total amount of acidic monomers Ma1, Ma2, and Ma3 present in the monomers M(i) is 2 to 10 wt. %, in particular 2.5 to 8 wt. %, in particular 3 to 7 wt. %, based on the total amount of monomers M(i) polymerized in the polymerization step. In particular, the relative proportion of the total amount of all acidic monomers Ma1, Ma2 and Ma3 present in the monomers polymerized in the other polymerization steps is at most 2% by weight, in particular at most 1.5% by weight, and in particular at most 1% by weight, based on the total amount of monomers polymerized in the other polymerization steps. In particular, at least 40% by weight, for example 40 to 100% by weight, in particular 50 to 95% by weight of the total amount of acidic monomers Ma1, Ma2 and Ma3 contained in the monomers M is polymerized in the polymerization step (i).

[0206] Mainly, the chain transfer compound may be present in any polymerization step of the free-radical multistage emulsion polymerization. Preferably, at least a portion of the chain transfer compound is present in step (i) of the multistage emulsion polymerization. In particular, at least 40% by weight, in particular at least 50% by weight of the total amount of chain transfer compounds is present in step (i) of the free-radical aqueous multistage emulsion polymerization. In particular, the total amount or at least 85% of the total amount of chain transfer compounds is present in step (i) of the free-radical aqueous multistage emulsion polymerization.

[0207] Preferably, the total amount of monomers M(i) polymerized in step (i) does not exceed 60% by weight, in particular 50% by weight, in particular 10 to 60% by weight and in particular 15 to 50% by weight, based on the total amount of monomers M. Accordingly, the total amount of monomers polymerized in any further steps is preferably at least 40% by weight, in particular at least 50% by weight and in particular 40 to 90% by weight and in particular 50 to 85% by weight, based on the total amount of monomers M.

[0208] Step (i) may be the first step of free radical multistage emulsion polymerization or any other step of free radical multistage emulsion polymerization. In a specific group (1) of embodiments, step (i) is the first step of free radical multistage emulsion polymerization. In another specific group (2) of embodiments, step (i) is the second step of free radical multistage emulsion polymerization.

[0209] In the embodiment of the specific group (1), the multistage emulsion polymerization preferably comprises:

[0210] a first step (1), wherein monomers M(1) are polymerized under free radical aqueous emulsion polymerization conditions, wherein the monomers M(1) include at least one monomer Ma1, at least one monomer Ma2, at least one monomer Ma3, at least one monomer Mb1, at least one monomer Mb2 and at least one monomer Mc, and

[0211] ii. a second step (2), wherein monomer M(2) is polymerized under conditions of free radical aqueous emulsion polymerization, wherein monomer M(2) comprises at least one monomer Mb1 and at least one monomer Mb2 and optionally at least one other monomer selected from monomers Ma1, Ma2, Ma3 and Mc.

[0212] In the embodiment of group (1), step (1) corresponds to step (i). The above disclosure about the relative amount of acidic monomers present in monomers M (i), the presence of chain transfer agents in step (i) and the relative amount of monomers M (i) relative to the total amount of monomers M applies equally to step (1). The multistage emulsion polymerization of the embodiment of group (1) may of course include one or more further subsequent steps (3), (4) ... (n.).

[0213] In the embodiment of the specific group (2), the multistage emulsion polymerization preferably comprises:

[0214] i) a first step (1') in which monomers M(1') are polymerized under free radical aqueous emulsion polymerization conditions, wherein the monomers M(1') comprise at least one monomer Mb1 and at least one monomer Mb2, and optionally at least one further monomer selected from the group consisting of monomers Ma1, Ma2, Ma3 and Mc, and

[0215] ii) a second step (2'), wherein monomers M(2') are polymerized under conditions of free radical aqueous emulsion polymerization, wherein monomers M(2') comprise at least one monomer Ma1, at least one monomer Ma2, at least one monomer Ma3, at least one monomer Mb1, at least one monomer Mb2 and at least one monomer Mc.

[0216] In the embodiment of group (2), step (2') corresponds to step (i). The above disclosure about the relative amount of acidic monomers present in monomers M (i), the presence of chain transfer agents in step (i) and the relative amount of monomers M (i) relative to the total amount of monomers M applies equally to step (2'). The multistage emulsion polymerization of the embodiment of group (2) may of course include one or more further subsequent steps (3'), (4') ... (n').

[0217] The free radical initiated aqueous emulsion polymerization is initiated by a free radical polymerization initiator (free radical initiator). These can in principle be peroxides or azo compounds. Of course, redox initiator systems are also useful. The peroxides used can in principle be inorganic peroxides, such as hydrogen peroxide or peroxodisulfates, such as monoalkali metal salts or dialkali metal salts or ammonium salts of peroxodisulfate, such as monosodium and disodium salts, potassium salts or ammonium salts, or organic peroxides, such as alkyl hydroperoxides, such as tert-butyl hydroperoxide, p-menthyl hydroperoxide or cumyl hydroperoxide, and dialkyl or diaryl peroxides, such as di-tert-butyl or dicumyl peroxide. The azo compounds used are essentially 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile) and 2,2'-azobis(amidinopropyl) dihydrochloride (AIBA, corresponding to V-50 of Wako Chemicals). Oxidants suitable for redox initiator systems are essentially the above-mentioned peroxides. Corresponding reducing agents which can be used are sulfur compounds with a low oxidation state, for example alkali metal sulfites, for example potassium sulfite and / or sodium sulfite, alkali metal hydrogensulfites, for example potassium hydrogensulfite and / or sodium hydrogensulfite, alkali metal pyrosulfites, for example potassium pyrosulfite and / or sodium pyrosulfite, formaldehyde sulfoxylates, for example potassium formaldehyde sulfoxylate and / or sodium formaldehyde sulfoxylate, alkali metal salts, in particular potassium and / or sodium salts of aliphatic sulfinic acids and alkali metal hydrogen sulfides, for example potassium and / or sodium hydrogen sulfide, salts of polyvalent metals, for example iron(II) sulfate, ammonium iron(II) sulfate, iron(II) phosphate, enediols, for example dihydroxymaleic acid, benzoin and / or ascorbic acid, and reducing sugars, for example sorbitol, glucose, fructose and / or dihydroxyacetone.

[0218] Preferred free radical initiators are inorganic peroxides, especially peroxodisulfates.

[0219] Typically, the amount of free radical initiator used, based on the total amount of monomers M, is from 0.05 to 2 pphm, preferably from 0.1 to 1 pphm, based on the total amount of monomers M.

[0220] The amount of free radical initiator required for the emulsion polymerization of the monomers M can be added completely to the polymerization vessel at the beginning. However, it is also possible to add no free radical initiator or only a portion of the free radical initiator, for example not more than 30% by weight, in particular not more than 20% by weight, based on the total amount of free radical initiator, and then any remaining amount of free radical initiator can be added to the free radical polymerization reaction under polymerization conditions. Preferably, at least 70%, in particular at least 80%, in particular at least 90% or the total amount of the polymerization initiator is added to the free radical polymerization reaction under polymerization conditions. During the free radical emulsion polymerization of the monomers M, the addition can be carried out in one or more portions, depending on the consumption, or continuously at a constant or variable flow rate.

[0221] In general, the term "polymerization conditions" is understood to mean those temperatures and pressures at which the free radical initiated aqueous emulsion polymerization proceeds at a sufficient polymerization rate. They depend in particular on the free radical initiator used. Advantageously, the type and amount of free radical initiator, the polymerization temperature and the polymerization pressure are selected so that a sufficient amount of initiating free radicals are always present to initiate or maintain the polymerization reaction.

[0222] Preferably, the free radical emulsion polymerization of the monomers M is carried out by the so-called feed method (also called monomer feed method), which means that at least 80%, in particular at least 90% or the total amount of the monomers M to be polymerized is metered into the polymerization reaction under polymerization conditions during a metering period P. The addition can be carried out batchwise, preferably continuously at a constant or variable feed rate. The duration of the period P may depend on the production equipment and may vary, for example, within 20 minutes to 12 hours. Typically, the duration of the period P is from 0.5 hours to 8 hours, in particular from 1 hour to 6 hours. In a multistage emulsion polymerization step, the total duration of all steps is generally within the above range. The duration of the individual steps is generally short.

[0223] Preferably, at least 70%, in particular at least 80%, in particular at least 90% or the total amount of the polymerization initiator is introduced into the emulsion polymerization simultaneously with the addition of the monomers.

[0224] Aqueous free radical emulsion polymerization is usually carried out in the presence of one or more suitable surfactants. These surfactants usually contain emulsifiers and provide micelles in which polymerization occurs, and they are used to stabilize monomer droplets during aqueous emulsion polymerization and growing polymer particles. The surfactant used in the emulsion polymerization is usually not separated from the polymer dispersion, but remains in the aqueous polymer dispersion obtainable by emulsion polymerization of the monomers M.

[0225] The surfactant may be selected from emulsifiers and protective colloids. In contrast to emulsifiers, protective colloids are understood to mean polymers with a molecular weight above 2000 Daltons, whereas emulsifiers generally have a lower molecular weight. The surfactant may be anionic or nonionic or a mixture of nonionic and anionic surfactants.

[0226] Anionic surfactants usually carry at least one anionic group, which is usually selected from phosphoric acid, phosphonic acid, sulfate and sulfonic acid groups. Anionic surfactants carrying at least one anionic group are usually used in the form of their alkali metal salts, especially their sodium salts or their ammonium salts.

[0227] Preferred anionic surfactants are anionic emulsifiers, in particular those with at least one sulfate or sulfonic acid group. Likewise, anionic emulsifiers with at least one phosphoric acid or phosphonic acid group can be used, either as the sole anionic emulsifier or in combination with one or more anionic emulsifiers with at least one sulfate or sulfonic acid group.

[0228] Examples of anionic emulsifiers carrying at least one sulfate or sulfonic acid group are, for example,

[0229] - Alkyl sulfonates, especially C8-C 22 - salts of alkyl sulfates, in particular alkali metal and ammonium salts,

[0230] - Sulfate monoesters of ethoxylated alkanols, especially ethoxylated C8-C 22 - salts of sulfuric acid monoesters of alkanols, in particular alkali metal salts and ammonium salts, preferably with an ethoxyl group level (EO level) of 2 to 40,

[0231] - Sulfate monoesters of ethoxylated alkylphenols, especially ethoxylated C4-C 18 - salts of sulfuric acid monoesters of alkylphenols (EO level preferably from 3 to 40), in particular alkali metal and ammonium salts,

[0232] -Alkyl sulfonic acid, especially C8-C 22 - salts of alkylsulfonic acids, in particular alkali metal and ammonium salts,

[0233] - dialkyl esters, especially di-C4-C 18 Salts of alkyl esters, in particular alkali metal and ammonium salts,

[0234] - Salts of alkylbenzenesulfonic acids, especially C4-C 22 - salts of alkylbenzenesulfonic acids, in particular alkali metal and ammonium salts, and

[0235] - mono- or di-sulfonated alkyl-substituted diphenyl ethers, e.g., with C4-C 24-alkyl bis(benzenesulfonic acid) ether salts, in particular alkali metal salts and ammonium salts. The latter are common knowledge, for example from US-A-4269749, and are commercially available, for example as (Dow Chemical Company).

[0236] Mixtures of the above salts are also suitable.

[0237] Examples of anionic emulsifiers containing a phosphate group or a phosphate group include, but are not limited to, the following salts selected from the group consisting of:

[0238] - monoalkyl and dialkyl phosphates, especially C8-C 22 - salts of alkyl phosphates, in particular alkali metal and ammonium salts,

[0239] - Salts of phosphoric acid monoesters of C2-C3-alkoxylated alkanols, in particular alkali metal salts and ammonium salts, preferably with a degree of alkoxylation of 2 to 40, in particular 3 to 30, e.g. ethoxylated C8-C 22 Phosphoric acid monoesters of -alkanols, preferably with an ethoxylation level (EO level) of 2 to 40, propoxylated C8-C 22 Phosphoric acid monoesters of -alkanols, preferably with a propoxyl level (PO level) of 2 to 40, and ethoxylated and propoxylated C8-C 22 - phosphoric acid monoesters of alkanols, preferably with an ethoxy level of 1 to 20 (EO level) and a propoxy level of 1 to 20,

[0240] - ethoxylated alkylphenol phosphate monoesters, especially ethoxylated C4-C 18 - salts of phosphoric acid monoesters of alkylphenols (preferably with a degree of ethylene oxide of 3 to 40), in particular alkali metal and ammonium salts,

[0241] - alkylphosphonic acid, especially C8-C 22 - salts of alkylphosphonic acids, in particular alkali metal and ammonium salts, and

[0242] -Alkylbenzenephosphonic acid, especially C4-C 22 - Salts of alkylbenzene phosphoric acids, especially alkali metal and ammonium salts

[0243] Other suitable anionic surfactants may be found in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Volume XIV / 1, Makromolekulare Stoffe [Macromolecular Substances], Georg-Thieme-Verlag, Stuttgart, 1961, pages 192-208.

[0244] Preferably, the surfactant comprises at least one anionic emulsifier, which carries at least one sulfate group or sulfonic acid group. The at least one anionic emulsifier carrying at least one sulfate group or sulfonic acid group may be the only type of anionic emulsifier. However, a mixture of at least one anionic emulsifier carrying at least one sulfate group or sulfonic acid group and at least one anionic emulsifier carrying at least one phosphoric acid group or phosphonic acid group may also be used. In such a mixture, the amount of at least one anionic emulsifier carrying at least one sulfate group or sulfonic acid group is preferably at least 50% by weight, based on the total weight of the anionic surfactant used in the method of the present invention. In particular, the amount of the anionic emulsifier carrying at least one phosphoric acid group or phosphonic acid group does not exceed 20% by weight, based on the total weight of the anionic surfactant used in the method of the present invention.

[0245] Preferred anionic surfactants are anionic emulsifiers selected from the following components, including mixtures thereof:

[0246] -Alkyl sulfates, especially C8-C 22 Salts of alkyl sulfates, especially the alkali metal and ammonium salts,

[0247] - Sulfate monoesters of ethoxylated alkanols, especially ethoxylated C8-C 22 - salts of sulfuric acid monoesters of alkanols, in particular alkali metal salts, preferably with an ethoxyl group level (EO level) of 2 to 40,

[0248] - Sulfate monoesters of ethoxylated alkylphenols, especially ethoxylated C4-C 18 - salts of sulfuric acid monoesters of alkylphenols (EO level preferably 3 to 40), in particular alkali metal salts,

[0249] -Alkylbenzenesulfonic acids, especially C4-C 22 - salts of alkylbenzene sulfates, in particular alkali metal salts, and

[0250] - mono- or di-sulfonated alkyl-substituted diphenyl ethers, e.g., with C4-C 24 Salts of alkyl bis(benzenesulfonic acid) ethers, especially alkali metal salts.

[0251] Particularly preferred are anionic emulsifiers selected from the following components, including mixtures thereof:

[0252] -Alkyl sulfates, especially C8-C 22 Salts of alkyl sulfates, especially the alkali metal and ammonium salts,

[0253] - Sulfate monoesters of ethoxylated alkanols, especially ethoxylated C8-C 22- salts, in particular alkali metal salts, of sulfuric acid monoesters of alkanols, preferably with an ethoxyl group level (EO level) of 2 to 40,

[0254] - mono- or di-sulfonated alkyl-substituted diphenyl ethers, e.g., with C4-C 24 Salts of alkyl bis(benzenesulfonic acid) ethers, especially alkali metal salts.

[0255] In addition to the above-mentioned anionic surfactants, the surfactant may also comprise one or more nonionic surface-active substances, which are in particular selected from nonionic emulsifiers. Suitable nonionic emulsifiers are, for example, aromatic aliphatic or aliphatic nonionic emulsifiers, such as ethoxylated mono-, di- and trialkylphenols (EO level: 3 to 50, alkyl radical: C4-C 10 ), long chain alcohol ethoxylates (EO level: 3 to 100, alkyl group: C8-C 36 ), and polyethylene oxide / polypropylene oxide homopolymers and copolymers. These may contain alkylene oxide units copolymerized in random distribution or in block form. Very suitable examples are EO / PO block copolymers. Preference is given to ethoxylates of long-chain alkanols, in particular those in which the alkyl radical is C8-C 30 Those having an average ethoxylation level of 5 to 100, with particular preference given to those having linear C 12 -C 20 Those having an alkyl radical of 10 to 50 and an average ethoxylation level as well as ethoxylated monoalkylphenols.

[0256] In a particular embodiment of the present invention, the surfactant used in the process according to the invention comprises less than 20% by weight, in particular not more than 10% by weight, of nonionic surfactants, based on the total amount of surfactants used in the process according to the invention, and in particular does not comprise any nonionic surfactants.

[0257] Preferably, the surfactant is used in such an amount that the amount of surfactant is 0.2 to 5% by weight, in particular 0.3 to 3% by weight, based on the monomers to be polymerized M. In a multistage emulsion step emulsion polymerization, the surfactant is used in such an amount that the amount of surfactant is generally 0.2 to 5% by weight, in particular 0.3 to 3% by weight, based on the total amount of monomers polymerized in the individual steps, for example in steps M(i) and M(ii), respectively.

[0258] Preferably, the major part, i.e. at least 80%, of the surfactant used is added to the emulsion polymerization simultaneously with the monomers. In particular, the monomers are added to the polymerization as an aqueous emulsion, which comprises at least 80% of the surfactant used for the emulsion polymerization.

[0259] It has been found to be advantageous to carry out the free radical emulsion polymerization of the monomers M in the presence of a seed latex. The seed latex is a polymer latex which is present in the aqueous polymerization medium before the start of the polymerization of the monomers M. The seed latex can help to better adjust the particle size or to obtain the final polymer latex in the free radical emulsion polymerization of the present invention.

[0260] In principle, various polymer latexes can be used as seed latex. For the purpose of the present invention, seed latexes are preferred in which the particle size of the polymer particles is relatively small. In particular, the Z average particle size of the polymer particles of the seed latex, measured by dynamic light scattering (DLS) at 20° C. (see below), is preferably from 10 to 80 nm, in particular from 10 nm to 50 nm. Preferably, the polymer particles of the seed latex are made of ethylenically unsaturated monomers, which contain at least 95% by weight of one or more monomers Mb1 and / or Mb2 as defined above, based on the total weight of the monomers forming the seed latex.

[0261] For this reason, the seed latex is usually charged to the polymerization vessel before the polymerization of the monomers M begins. In particular, the seed latex is charged to the polymerization vessel and then the polymerization conditions are established, for example by heating the mixture to the polymerization temperature. Before starting to add the monomers M, it is beneficial to charge at least a portion of the free radical initiator to the polymerization vessel. However, the monomers M and the free radical polymerization initiator may also be added to the polymerization vessel simultaneously.

[0262] The amount of seed latex calculated as solids may generally be from 0.05 to 5% by weight, in particular from 0.1 to 3% by weight, based on the total weight of the monomers in the monomer composition M to be polymerized.

[0263] If the free radical aqueous emulsion polymerization is carried out as the free radical multistage aqueous emulsion polymerization of the present invention, the second step is carried out after the first step. The second step can be carried out immediately after the monomer composition of the first step is completely added to the emulsion polymerization of the first step, that is, the polymerization of the monomer to be polymerized in the second step starts immediately after the addition of the monomer to be polymerized in the first step is completed. However, the polymerization of the first step can also be allowed to continue after the addition of the monomer to be polymerized in the first step is completed and before the polymerization of the monomer to be polymerized in the second step starts.

[0264] In the second step and any further steps of the multistage emulsion polymerization, the monomers can be added all at once to the polymer dispersion obtained in the first step. However, the free radical emulsion polymerization of the monomers to be polymerized in the second step is preferably carried out by a feeding method as described above. This means that in the second step and any further steps, at least 80%, in particular at least 90% or the total amount of the monomers to be polymerized are metered into the polymerization reaction under polymerization conditions during the metering period P'. The duration of the individual cycles P and P' may depend on the production equipment and may vary, for example, from 10 minutes to 8 hours. Typically, the duration in the individual cycles P and P' is from 20 minutes to 7 hours, in particular from 30 minutes to 5 hours.

[0265] The free radical aqueous emulsion polymerization of the present invention can be carried out in a temperature range of 0 to 170° C. The temperature employed is generally 50 to 120° C., typically 60 to 120° C. and typically 70 to 110° C. The free radical aqueous emulsion polymerization of the present invention can be carried out at a pressure less than, equal to or greater than 1 atm (atmospheric pressure), so the polymerization temperature can exceed 100° C. and can be as high as 170° C. The polymerization of the monomers is generally carried out at ambient pressure, but can also be carried out at elevated pressure. In this case, the pressure can take values ​​of 1.2, 1.5, 2, 5, 10, 15 bar (absolute) or higher. If the emulsion polymerization is carried out under reduced pressure, a pressure of 950 mbar, typically 900 mbar and often 850 mbar (absolute) is established. Advantageously, the free radical aqueous emulsion polymerization of the present invention is carried out at ambient pressure (about 1 atm) excluding oxygen, for example under an inert gas atmosphere, for example under nitrogen or argon.

[0266] The free-radical emulsion polymerization according to the invention is usually carried out in an aqueous polymerization medium which, in addition to water, contains at least one surface-active substance, a so-called surfactant, for stabilizing the emulsion of monomers and the polymer particles of the polymer latex. Suitable surfactants are those mentioned above.

[0267] Apart from this, the conditions required for carrying out the free-radical emulsion polymerization are sufficiently familiar to the person skilled in the art, for example from the prior art cited at the outset and from "Emulsion Polymerization" in the Encyclopedia of Polymer Science and Engineering [Emulsion Polymerization], Volume 8, p. 659 et seq. (1987); D. C. Blackley, High Polymer Latexes, Volume 1, p. 35 et seq. (1966); H. Warson, Applications of Synthetic Resin Emulsions, Chapter 5, p. 246 et seq. (1972); D. Diederich, Chemiein unserer Zeit 24, pp. 135 to 142 (1990); Emulsion Polymerization, Interscience Publishers, New York (1965); DE-A 40 03 422 and Dispersionen synthetischer Hochpolymerer [Dispersions of Synthetic High Polymers], F. Springer-Verlag, Berlin (1969)].

[0268] It is often advantageous to subject the aqueous polymer dispersion obtained after the polymerization of the monomers M to an aftertreatment in order to reduce the residual monomer content. This aftertreatment can be carried out chemically, for example by using more effective free-radical initiator systems to complete the polymerization reaction (known as afterpolymerization), and / or physically, for example by stripping the aqueous polymer dispersion with steam or an inert gas. The corresponding chemical and physical methods are familiar to the person skilled in the art—see, for example, EP-A 771 328, DE-A 196 24 299, DE-A 196 21 027, DE-A 197 41 184, DE-A 197 41 187, DE-A 198 05 122, DE-A 198 28 183, DE-A 198 39 199, DE-A 198 40 586 and DE-A 198 47 115. The advantage of a combined chemical and physical aftertreatment is that it removes not only unconverted ethylenically unsaturated monomers but also other disruptive volatile organic components (VOCs) from the aqueous polymer dispersion.

[0269] Since the polymer contained in the aqueous polymer dispersion contains acidic groups from monomers Ma1, Ma2 and Ma3 and optionally from a polymerization initiator, the aqueous polymer dispersion obtained by the method of the present invention is often neutralized before being formulated as a coating composition. The neutralization of the acidic groups of the polymer is achieved by a neutralizing agent known to those skilled in the art after polymerization and / or during polymerization. For example, the neutralizing agent can be added to the combined feed with the monomer to be polymerized, or added to a separate feed. Suitable neutralizing agents include organic amines, alkali metal hydroxides, ammonium hydroxide. In particular, neutralization is achieved by using ammonia or alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide.

[0270] Preferably, the pH of the final polymer dispersion is at least pH 7, such as pH 7 to pH 12, prior to use in a coating composition.

[0271] The aqueous polymer dispersions according to the invention can be used in particular as binders or cobinders in aqueous coating compositions, in particular in architectural coating compositions and coating compositions for mineral moldings.

[0272] Aqueous coating compositions generally contain the aqueous polymer dispersion of the invention and therefore the polymer polymerized in fine particle form from the monomers M and the surface-active substances used in the emulsion polymerization, such as emulsifiers and / or protective colloids.

[0273] Aqueous coating compositions generally contain not more than 50% by weight, more particularly not more than 20% by weight, in particular not more than 10% by weight, of water-miscible solvents, based on the total weight of the coating composition. Very particularly preferably, the formulations according to the invention contain no organic solvents other than water, in addition to typical antifrost agents and film-forming assistants.

[0274] The aqueous polymer dispersion of the present invention can be used as a coating composition as such. However, the coating composition may contain typical formulation auxiliaries. The total amount of typical formulation auxiliaries is generally 0.1 to 30% by weight, in particular 0.5 to 10% by weight, of the aqueous coating composition.

[0275] Conventional formulation aids include, but are not limited to, pigment dispersants, wetting agents, rheology modifiers, leveling agents, biocides, defoamers, antifreeze agents, flow promoters, and the above-mentioned film-forming aids. Other suitable formulation aids and components are described, for example, in J. Bieleman, "Additives for Coatings", Wiley-VCH, Weinheim 2000; TC Patton, ed., "Paint Flow and Pigment Dispersions", 2nd edition, John Wiley & Sons 1978; and M. Schwartz and R. Baumstark, "Water-Based Acrylates for Decorative Coatings", Curt R. Vincentz Verlag, Hanover 2001.

[0276] In addition, the aqueous coating composition of the present invention may also include inorganic fillers and / or pigments. Typical pigments are, for example, titanium dioxide, preferably titanium dioxide, barium sulfate, zinc oxide or lithopone (zinc sulfide + barium sulfate) in the form of rutile. For decorative purposes, the preparation may also include colored pigments, examples of which are iron oxide, carbon black, graphite, zinc yellow, zinc green, ultramarine, manganese black, antimony black, manganese violet, Paris blue or Schweinfurt green. The preparation may also include pigments that reflect IR radiation, i.e., IR reflective pigments, such as pigments based on Fe / Cr mixed oxides and titanium-based mixed oxides, such as antimony nickel titanium oxide. Suitable fillers include aluminosilicates, such as feldspar, silicates, such as kaolin, talc, mica, magnesite, alkaline earth metal carbonates, such as calcium carbonate, such as calcite or chalk forms, magnesium carbonate, dolomite, alkaline earth metal sulfates, such as calcium sulfate, silicon dioxide, etc.

[0277] The ratio of pigments and fillers in an aqueous coating composition can be described in a manner known per se by the pigment volume concentration (PVC). The PVC describes the ratio of the volume of pigment (VP) and filler (VF) relative to the total volume, consisting of the volume of binder (VB), pigment (VP) and filler (VF) in the dry coating film, expressed as a percentage: PVC=(VP+VF)×100 / (VP+VF+VB). Preferably, the PVC value does not exceed 60 and is in particular from 0 to 50.

[0278] The aqueous coating composition of the present invention may also contain a crosslinking additive. Such additives include the following: aromatic ketones, such as alkyl phenyl ketones, which, if appropriate, have one or more substituents on the phenyl ring, or benzophenone and substituted benzophenone as photoinitiators. Photoinitiators suitable for this purpose are known, for example, from DE-A 38 27 975 and EP-A 417 568. Suitable compounds with crosslinking are also water-soluble compounds with at least two amino groups, examples being dihydrazides of aliphatic dicarboxylic acids according to DE-A 39 01 073, if the polymer formed by the polymerized monomer M contains monomers in copolymerized form containing carbonyl groups.

[0279] The aqueous coating compositions of the invention include, for example, clearcoat (clear varnish) formulations, surface coating formulations, such as paints, renders or coating systems.

[0280] According to a preferred embodiment of the invention, the aqueous coating compositions are formulated as varnish materials. In that case, they generally contain 10% to 60% by weight, preferably 40% to 55% by weight, of at least one polymer formed from polymerized monomers M, based on their total weight, and 0.1% to 30% by weight, preferably 0.5% to 10% by weight, of typical auxiliaries, more particularly defoamers and / or film-forming aids.

[0281] Another embodiment of the invention relates to an aqueous coating composition in the form of a colored and / or filled formulation. In this case, the total amount of polymer formed by polymerized monomers M in the aqueous formulation is 10 to 60% by weight, preferably 20 to 40% by weight; the content of auxiliary agents is 0.1 to 30% by weight and preferably 0.5 to 10% by weight, and the content of fillers and / or pigments is 10 to 60% by weight or more particularly 10% to 40% by weight. Preferably, the PVC is 2 to 50. In addition, in addition to film-forming aids and defoamers, the colored formulation preferably also contains a dispersant and / or a wetting agent.

[0282] The clearcoat materials and pigmented coating materials of the invention may comprise further typical auxiliaries, such as wetting agents, in-can and in-film preservatives, thickeners, defoamers, flow promoters and antifreeze agents, for example, in the amounts usually employed per se.

[0283] The present invention also relates to the use of the aqueous coating composition of the present invention for permanently coating a substrate and thus to a method for producing a permanent coating on the surface of a substrate. The method comprises

[0284] (a) applying the aqueous coating composition according to the present invention to the surface to be coated, and

[0285] (b) drying the composition to produce a permanent coating.

[0286] The aqueous coating composition can be applied to the surface and / or substrate to be coated in a conventional manner, such as, for example, by applying with a brush or roller, by spraying, by dipping, by roller coating, by curtain coating or by rod coating. The coating of the surface and / or substrate is carried out in such a way that the surface and / or substrate is first coated with the composition of the present invention and then the aqueous composition is subjected to a drying step. The drying step is usually carried out at a temperature of +5 to +80°C, in particular +10 to +70°C. Typically, a temperature of +5 to +25°C is sufficient to obtain an acceptable permanent coating. However, higher temperatures will accelerate the drying rate, and temperatures up to +80°C or up to +70°C may also be suitable.

[0287] In principle, waterborne coating compositions of the present invention can be applied to any substrate, and the substrate is usually coated by waterborne coating compositions. Waterborne coating compositions can be applied to surfaces, such as metal, asphalt, concrete, fiber cement board, stone, pottery, mineral, wood, plastics, polymer and glass. Waterborne coating compositions can be applied to inner or outer surfaces, such as building surfaces, such as roofs, walls, floors and ceilings.

[0288] The aqueous coating compositions of the present invention are particularly suitable for coating mineral substrates, including stone walls and concrete surfaces, and are particularly suitable for coating the surfaces of formed mineral articles, such as concrete roof tiles and fiber cement boards.

[0289] The coating of shaped mineral articles by means of aqueous coating compositions is well known, for example from the prior art discussed at the outset, and from EP 1069093 and EP 3498783. In the case of coating shaped mineral articles, the application rate of the aqueous polymer preparation to be applied for protection is generally 50 to 700 g / m 2 (calculated wet). Use can be carried out in a conventional manner, by spraying, plastering, scraping, rolling or pouring, including curtain coating. The method of the present invention can be used for cured and newly prepared ("green") shaped mineral products. It is particularly suitable for protecting shaped mineral products (cast concrete) containing cement as a mineral binder. In a particularly advantageous manner, it can prevent weathering on concrete roofing tiles. The latter are usually made of cement mortar, the viscosity of which allows final shaping. They are usually hardened at a temperature of 40 to 80°C. Usually, hardening is carried out at a relative humidity of 30 to 90%. After shaping (for example by extrusion), but usually before hardening, the concrete roofing tiles are surface-coated with the aqueous coating composition of the present invention and then stored in a curing chamber for 6 to 12 hours, wherein the above-mentioned temperature and humidity conditions are usually subject. During this time, they cure, while the coating composition forms a permanent film. In some cases, further applications are carried out with the coating composition after the curing operation, followed by drying. Then, drying can be carried out at the above-mentioned temperature, for example 5 to 50°C.

[0290] Example

[0291] The following abbreviations are used in the text below:

[0292] %bw weight%

[0293] AA Acrylic

[0294] AMA Allyl Methacrylate

[0295] AMPS: 2-Acrylamido-2-methylpropanesulfonic acid

[0296] AM Acrylamide

[0297] DLS: Dynamic Light Scattering

[0298] EHTG 2-Ethylhexyl thioglycolate

[0299] EO: Ethylene oxide

[0300] HDC: Hydrodynamic Chromatography

[0301] HDC-PS: Particle size determined by HDC

[0302] HPPS: High Performance Particle Size Analyzer

[0303] IA itaconic acid

[0304] MAA: Methacrylic acid

[0305] nd Not determined

[0306] no not observed

[0307] n-BuA n-Butyl acrylate

[0308] PDI: Polydispersity Index

[0309] rpm: revolutions per minute

[0310] SC: solid content

[0311] SDS: Sodium Lauryl Sulfate (Sodium Lauryl Sulfate)

[0312] t-DMK tert-dodecyl mercaptan

[0313] MEMO 3-(Trimethoxysilyl)propyl methacrylate

[0314] WU: Water Absorption

[0315] Z-PS: Particle size determined by DLS

[0316] 1. Analysis and Characterization

[0317] 1.1 Characterization of dispersions

[0318] i) The solids content of the polymer dispersion was measured according to the standard method DIN EN ISO 3251:2008-06.

[0319] ii) The pH value of the polymer dispersion was measured according to the standard method DIN EN 1262:2004-01.

[0320] iii) The glass transition temperature was determined by means of a DSC instrument (Q 2000 series from TA Instruments) by means of the DSC method (Differential Scanning Calorimetry, 20 K / min, midpoint measurement, DIN 53765:1994-03).

[0321] iv) Determination of the particle size distribution of the polymer dispersions by DLS The particle size of the polymer latexes was determined by dynamic light scattering (DLS, also known as quasi-elastic light scattering) by HPPS from Malvern Instruments, England on aqueous polymer dispersions diluted to 0.001 to 0.5 wt. % with deionized water at 22° C. Reported are the cumulant Z-average diameters calculated from the measured autocorrelation function (ISO standard 13321).

[0322] v) Determination of the particle size distribution of polymer dispersions by HDC The measurements were performed using a PL-PSDA particle size distribution analyzer (Polymer Laboratories, Inc.). A small amount of polymer latex sample was injected into an aqueous eluent containing an emulsifier to give a concentration of about 0.5 g / l. The mixture was pumped through a glass capillary of about 15 mm in diameter filled with polystyrene balls. Due to their hydrodynamic diameter, smaller particles can spatially enter slower flowing areas in the capillary, so on average, smaller particles experience a slower elution flow. Finally, the fractionation was monitored using a UV detector that measured extinction at a fixed wavelength of 254 nm.

[0323] vi) The minimum film forming temperature (MFFT) was determined using a Kofler heating cell in accordance with DIN ISO 2115:2001-04.

[0324] 1.2 Application testing:

[0325] i) A film of the conditioned latex dispersion described in the above example was cast onto a polyethylene foil using a doctor blade with a gap width of 600 μm. The resulting film was dried at room temperature for 24 hours. Thereafter, the film was separated from the polyethylene foil and dried in an oven at 60°C for three days. Using a gauge, two samples of size 5 cm*4 cm were cut from the film. The specimens were immersed in a stainless steel mesh in a deionized water container for 72 hours. Thereafter, the samples were removed from the stainless steel mesh and dried in an oven at 60°C to constant weight and weighed (w 干 The sample was then placed again in the stainless steel mesh in the deionized water container for 24 h, removed from the container and mesh and dried with a towel to remove all adhering water droplets and immediately weighed again (w 湿 ). The water absorption (%) is calculated by the following formula

[0326]

[0327] 2. Materials used to prepare polymer dispersions

[0328] - Seed latex S1: acrylic seed particles with a solids content of 33 wt% and a Z-average particle size of 30 nm as determined by DLS

[0329] -Emulsifier E1: Sodium lauryl sulfate

[0330] - Emulsifier E2: Sodium salt of C12 / 14 alcohol ether sulfate with about 2 EO units

[0331] - Emulsifier E3: Sodium salt of C12 / 14 alcohol ether sulfate with about 4 EO units

[0332] - Coagulating agent CA1: 2-(2-butoxyethoxy)ethanol

[0333] - Coagulating agent CA2: dibutyl adipate

[0334] If not otherwise stated, the water used in the preparation examples was deionized water.

[0335] 3. Preparation of polymer dispersion

[0336] Embodiment 1:

[0337] The polymerization vessel equipped with a stirrer and three separate feed lines was charged as follows:

[0338] Initial Charge #0:

[0339] 402.78g water

[0340] 19.69g Seed Latex S1

[0341] In the first addition vessel, prepare Feed / Emulsion #1 by mixing the following components:

[0342] Feed / Emulsion #1

[0343]

[0344] In a second addition vessel, prepare Feed / Emulsion #2 by mixing the following components:

[0345] Feed / Emulsion #2

[0346]

[0347]

[0348] In a third addition vessel, prepare the following Feed / Initiator Solution #3 by dissolving:

[0349] Feed / Initiator Solution #3:

[0350] 3.83g sodium persulfate dissolved in 50.79g water

[0351] In a fourth addition vessel, prepare the following Feed / Oxidation Solution #4 by dissolving:

[0352] Feed / Oxidation Solution #4:

[0353] 1.26g tert-butyl hydroperoxide dissolved in 11.34g water

[0354] In the fifth addition vessel, prepare the following Feed / Reduction Solution #5 by dissolving:

[0355] Feed / Reduction Solution #5:

[0356] 0.72g sodium bisulfite dissolved in 7.68g water and mixed with 0.43g acetone

[0357] Initial Charge #0 was heated to a polymerization temperature of 83°C with stirring at 150 rpm. After reaching a reaction temperature of 83°C, Feed / Emulsion #1 was then fed into the reaction vessel over 60 minutes. In parallel, starting simultaneously with Feed / Emulsion #1 but from a spatially separate feed vessel, 30 wt% of Feed / Initiator Solution #3 was fed into the reaction vessel over 60 minutes. After the addition of Feed / Emulsion #1 was complete, Feed / Emulsion #2 was fed into the reaction vessel over 140 minutes. In parallel, starting simultaneously with Feed / Emulsion #2 but from a spatially separate feed vessel, 70 wt% of Feed / Initiator Solution #3 was fed into the reaction vessel over 140 minutes.

[0358] After the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction vessel was stirred for an additional 20 minutes, after which a solution of 2.16 g of sodium hydroxide dissolved in 37.23 g of water was added over 20 minutes. After the addition of the aqueous sodium hydroxide solution was complete, Feed / Oxidation Solution #4 and Feed / Reduction Solution #5 were fed to the reaction vessel at 83° C. over 60 minutes, starting simultaneously from two spatially separate feed vessels. After the addition of Feed / Oxidation Solution #4 and Feed / Reduction Solution #5 was complete, 4.44 g of sodium hydroxide dissolved in 76.22 g of water and 230.69 g of water was added to the reaction vessel and the vessel was cooled to 25° C.

[0359] The particle size measured by dynamic light scattering was 168 nm. The pH of the final dispersion was approximately 9.0.

[0360] One day later, 180 g of coalescing agent CA1 was added to the dispersion and the mixture was allowed to equilibrate for 24 hours. The solids content of the final dispersion was about 47%.

[0361] Embodiment 2:

[0362] The polymer of Inventive Example 2 was prepared similar to the protocol set forth in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below, but after the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction vessel was stirred for an additional 20 minutes, and then a solution of 4.69 g of sodium hydroxide dissolved in 41.61 g of water was added over 20 minutes.

[0363] Embodiment 3, 4, 5, 6 and 9:

[0364] The polymers of Inventive Examples 3, 4, 5, 6 and 9 were prepared similar to the protocol given in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2 and coalescing agents as shown in Table 1 below.

[0365] Embodiment 7:

[0366] The polymer of Inventive Example 7 was prepared similarly to the protocol set forth in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below, except that after the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction vessel was stirred for an additional 20 minutes, and then a solution of 2.79 g of sodium hydroxide dissolved in 48.18 g of water was added over 20 minutes.

[0367] Embodiment 8:

[0368] The polymer of Inventive Example 8 was prepared similarly to the protocol given in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below, and then both Feed / Emulsion #1 and Feed / Emulsion #2 were added to the reactor over 100 minutes. Beginning with Feed / Emulsion #1, Feed / Initiator Solution #3 was fed continuously over 200 minutes. After the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction vessel was stirred for an additional 20 minutes, after which a solution of 2.79 g of sodium hydroxide dissolved in 48.18 g of water was added over 20 minutes.

[0369] Embodiment 10:

[0370] The polymer of Inventive Example 10 was prepared similarly to the protocol set forth in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below, but after the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction vessel was stirred for an additional 20 minutes and then a solution of 2.41 g of sodium hydroxide dissolved in 41.61 g of water was added over 20 minutes. After the addition of Feed / Oxidizing Solution #4 and Feed / Reducing Solution #5 was complete, 3.55 g of sodium hydroxide dissolved in 60.98 g of water was added to the reaction vessel.

[0371] Embodiment 11:

[0372] The polymer of Inventive Example 11 was prepared similarly to the protocol given in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below, but after the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete. The reaction vessel was stirred for an additional 20 minutes, and then a solution of 2.41 g of sodium hydroxide dissolved in 41.61 g of water was added over 20 minutes. After the addition of Feed / Oxidizing Solution #4 and Feed / Reducing Solution #5 was complete, 4.31 g of sodium hydroxide dissolved in 74.04 g of water was added to the reaction vessel.

[0373] Embodiment 12:

[0374] The polymer of Inventive Example 12 was prepared similar to the protocol set forth in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below, but with 6.28 g AMPS in the initial charge. After the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction vessel was stirred for an additional 20 minutes, and then a solution of 2.03 g sodium hydroxide dissolved in 35.04 g water was added to the reaction vessel over 20 minutes. After the addition of Feed / Oxidizing Solution #4 and Feed / Reducing Solution #5 was complete, 3.81 g sodium hydroxide dissolved in 65.33 g water was added to the reaction vessel.

[0375] Embodiment 13:

[0376] The preparation of the polymer of Inventive Example 13 was similar to the protocol given in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below; and Feed / Initiator Solution #3 was prepared by dissolving 1.90 g of sodium persulfate in 50.79 g of water.

[0377] Embodiment 14:

[0378] The polymer of Inventive Example 14 was prepared similarly to the protocol set forth in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below; after the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction mixture was stirred for an additional 20 minutes, and then a solution of 2.41 g of sodium hydroxide dissolved in 41.61 g of water was added over 20 minutes.

[0379] Examples 15 and 16:

[0380] The polymers of Inventive Examples 15 and 16 were prepared similarly to the protocol given in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below; the initial charge contained 8.49 g of itaconic acid. After the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction mixture was stirred for an additional 20 minutes, after which a solution of 2.41 g of sodium hydroxide dissolved in 41.61 g of water was added over 20 minutes.

[0381] Examples 17, 18 and 19:

[0382] The polymers of Inventive Examples 17, 18 and 19 were prepared similarly to the protocol set forth in Inventive Example 1, except that Feed / Emulsion #1, Feed / Emulsion #2 and coalescing agent were used as shown in Table 1 below; after the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 were complete, the reaction mixture was stirred for an additional 20 minutes, and then a solution of 2.41 g of sodium hydroxide dissolved in 41.61 g of water was added over 20 minutes.

[0383] Embodiment 20:

[0384] The polymer of Inventive Example 20 was prepared similarly to the protocol set forth in Inventive Example 1, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 1 below, but with a pre-charge containing 18.62 grains of Seed Latex S1, Feed / Emulsion #1 and 44.36 wt % of Feed / Initiator Solution #3 added simultaneously over 100 minutes, followed by Feed / Emulsion #2 and 55.64 wt % of Feed / Initiator Solution #3 added simultaneously over 120 minutes. After the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction vessel was stirred for an additional 30 minutes, and then a solution of 6.32 g of sodium hydroxide dissolved in 108.54 g of water was added over 80 minutes.

[0385] Table 1 also includes feed / emulsion #1, feed / emulsion #2 and coalescing agent of Example 1. Properties of the resulting polymer dispersions, such as particle size measured by dynamic light scattering, pH of the final dispersion and solids content of the final dispersion are also given in Table 1.

[0386]

[0387]

[0388]

[0389]

[0390] Comparative Examples C1-C5

[0391] Comparative Examples C1 and C2:

[0392] The preparation of polymers of C1 and C2 was similar to the protocol given in Example 1 of the present invention, but using Feed / Emulsion #1, Feed / Emulsion #2, and coalescing agent as shown in Table 2 below, and initial Charge #0 containing 32.20 g of S1 and 9.36 g of 2-acrylamido-2-methylpropanesulfonic acid. Feed / Emulsion #1 was fed to the reactor vessel over 60 minutes. Feed / Emulsion #2 was fed to the reactor vessel over 120 minutes. Feed / Initiator Solution #3 was fed to the reactor vessel over 180 minutes. After the addition of Feed / Oxidizing Solution #4 and Feed / Reducing Solution #5 was completed, 0.51 g of ammonia dissolved in 1.52 g of water was added to the reaction vessel.

[0393] Comparative Example C3:

[0394] The preparation of C3 polymer was similar to the protocol given in Example 1 of the present invention, but using Feed / Emulsion #1, Feed / Emulsion #2 and coalescing agent as shown in Table 2 below, and initial Charge #0 contained 39.02 g S1 and 378.09 g water. Feed / Emulsion #1 and Feed / Emulsion #2 were then each fed to the reactor over 120 minutes. After the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was complete, the reaction mixture was stirred for an additional 20 minutes, after which a solution of 4.03 g sodium hydroxide dissolved in 96.72 g water was added over 20 minutes. After the addition of Feed / Oxidation Solution #4 and Feed / Reduction Solution #5 was complete, 4.17 g sodium hydroxide dissolved in 204.33 g water was added to the reaction vessel.

[0395] Comparative Example C4:

[0396] The preparation of C4 polymer was similar to the protocol given in Example 1 of the present invention, but using feed / emulsion #1, feed / emulsion #2 and coalescing agent as shown in Table 2 below, and after the addition of feed / emulsion #2 and feed / initiator solution #3 was completed, the reaction mixture was stirred for an additional 20 minutes, and then a solution of 1.65 g of sodium hydroxide dissolved in 28.47 g of water was added over 20 minutes. After the addition of feed / oxidizing solution #4 and feed / reducing solution #5 was completed, 3.04 g of sodium hydroxide dissolved in 52.27 g of water was added to the reaction vessel.

[0397] Comparative Example C5:

[0398] The preparation of C4 polymer was similar to the protocol given in Example 1 of the present invention, but using Feed / Emulsion #1, Feed / Emulsion #2 and coalescing agent as shown in Table 2 below, and after the addition of Feed / Emulsion #2 and Feed / Initiator Solution #3 was completed, the reaction mixture was stirred for an additional 20 minutes, and then a solution of 2.41 g of sodium hydroxide dissolved in 41.61 g of water was added over 20 minutes.

[0399] The properties of the comparative polymer dispersions obtained, such as particle size measured by dynamic light scattering, pH value of the final dispersion and solids content of the final dispersion are also given in Table 2.

[0400] Table 2

[0401]

[0402]

[0403] *Solid content of final dispersion

[0404] 4. Apply test results

[0405] 4.1 Water absorption

[0406] The polymer dispersions of Examples 1 to 20 of the invention and Comparative Examples C1 to C5 were formulated with coalescents as described in Tables 1 and 2, respectively. These formulations were used to prepare test samples as described above. The results are summarized in Table 3 below.

[0407] Table 3: Water absorption of the films obtained from Examples 1 to 13 and 20 and Comparative Examples C1 to C5, respectively

[0408] Example Water absorption / % C1 16.0 C2 12.0 C3 10.0 C4 9.1 C5 9.1 1 5.0 2 5.2 3 3.1 4 3.1 5 3.5 6 5.9 7 4.0 8 2.8 9 6.3 10 4.0 11 4.7 12 6.9 13 6.0 14 4.9 15 5.0 16 4.4 17 4.4 18 3.4 19 3.9 20 5.2

Claims

1. Aqueous polymer dispersions obtainable by free radical aqueous emulsion polymerization of ethylenically unsaturated monomers M, wherein the monomers M comprise a) 0.5 to 7.0% by weight of the following combinations, based on the total weight of the monomers M a1) 0.15 to 2.0% by weight of at least one monomer Ma1 selected from monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms and their salts, based on the total amount of monomers M; a2) 0.2 to 3.0% by weight of at least one monomer Ma2 selected from monoethylenically unsaturated dicarboxylic acids having 4 to 8 carbon atoms and their salts, based on the total amount of monomers M; a3) 0.15 to 2.0% by weight of at least one monomer Ma3 selected from monoethylenically unsaturated monosulfonic acids having 2 to 10 carbon atoms and their salts, based on the total amount of monomers M; b1) 60 to 79.45% by weight of at least one monomer Mb1, based on the total weight of the monomers M, chosen from nonionic monoethylenically unsaturated monomers having a solubility in deionized water at 25° C. and 1 bar of up to 60 g / L and whose homopolymers have a glass transition temperature Tg of at least 50° C.; b2) 20 to 39.45% by weight of at least one monomer Mb2, based on the total amount of monomers M, chosen from nonionic monoethylenically unsaturated monomers having a solubility in deionized water at 25° C. and 1 bar of up to 60 g / L and whose homopolymers have a glass transition temperature Tg of up to 40° C.; c) 0.05 to 2.0% by weight of at least one crosslinking monomer Mc; The aqueous emulsion polymerization is carried out at least partly in the presence of a chain transfer compound.

2. The aqueous polymer dispersion of claim 1, wherein the monomers M contain 0.6 to 6% by weight of the following combinations, based on the total amount of monomers M: a1) 0.15 to 2.0% by weight of at least one monomer Ma1, based on the total amount of the monomers M; a2) 0.2 to 3.0% by weight of at least one monomer Ma2, based on the total amount of the monomers M; a3) 0.15 to 1.5% by weight, based on the total amount of the monomers M, of at least one monomer Ma3.

3. The aqueous polymer dispersion of claim 2, wherein the monomers M contain 1.0 to 4.0% by weight of the following combinations, based on the total amount of monomers M: a1) 0.15 to 2.0% by weight of at least one monomer Ma1, based on the total amount of the monomers M; a2) 0.2 to 3.0% by weight of at least one monomer Ma2, based on the total amount of the monomers M; a3) 0.15 to 1.5% by weight, based on the total amount of the monomers M, of at least one monomer Ma3.

4. The aqueous polymer dispersion of claim 1 or 2, wherein the monomer Ma1 is selected from acrylic acid, methacrylic acid and mixtures thereof, the monomer Ma2 is selected from itaconic acid, mesaconic acid and citraconic acid, and the monomer Ma3 is 2-acrylamido-2-methylpropanesulfonic acid or its sodium salt.

5. The aqueous polymer dispersion of claim 4, wherein the monomer Ma2 is itaconic acid. 6 . The aqueous polymer dispersion according to claim 1 , wherein the monomers M comprise from 0.05 to 1.5% by weight, based on the total amount of monomers M, of at least one crosslinking monomer Mc. 7 . The aqueous polymer dispersion according to claim 6 , wherein the monomers M comprise from 0.08 to 1.0% by weight, based on the total amount of monomers M, of at least one crosslinking monomer Mc.

8. The aqueous polymer dispersion of claim 1 or 2, wherein the crosslinking monomer Mc is selected from polyethylenically unsaturated monomers having at least two non-conjugated ethylenically unsaturated double bonds and monoethylenically unsaturated monomers having at least one further functional group capable of reacting with itself or with a carboxylic acid group, and mixtures thereof.

9. The aqueous polymer dispersion according to claim 1 or 2, wherein the monomer Mb1 is selected from C1-C2-alkyl methacrylic acid esters, tert-butyl acrylate, tert-butyl methacrylate, monovinylaromatic monomers and mixtures thereof.

10. The aqueous polymer dispersion of claim 1 or 2, wherein the monomer Mb2 is selected from C1-C1 monomers of acrylic acid other than tert-butyl acrylate. 20 -alkyl esters, acrylic acid, C5-C 20 -cycloalkyl esters, C3-alkyl methacrylates, n-butyl methacrylate, C5-C 20 -alkyl esters, C5-C 20 - Cycloalkyl esters and mixtures thereof.

11. The aqueous polymer dispersion of claim 1 or 2, wherein the chain transfer compound has a mercapto group. 12 . The aqueous polymer dispersion according to claim 1 , wherein the amount of the chain transfer compound is from 0.05 to 1.2% by weight, based on the total amount of the monomers M.

13. The aqueous polymer dispersion according to claim 12, wherein the amount of the chain transfer compound is from 0.1 to 0.9% by weight, based on the total amount of the monomers M.

14. The aqueous polymer dispersion according to claim 1 or 2, wherein the free-radical aqueous emulsion polymerization is carried out as a free-radical aqueous multistage emulsion polymerization.

15. The aqueous polymer dispersion according to claim 14, wherein at least 40% by weight of the total amount of all monomers Ma1, Ma2 and Ma3 of the monomers M are contained in the monomers polymerized in one step of the free-radical aqueous multistage emulsion polymerization.

16. The aqueous polymer dispersion of claim 15, wherein at least 40% by weight of the total amount of said chain transfer compounds is present in said step of free-radical aqueous multistage emulsion polymerization.

17. The aqueous polymer dispersion according to claim 15, wherein the amount of monomers polymerized in said step is from 10 to 50% by weight, based on the total amount of monomers M polymerized in said free-radical aqueous multistage emulsion polymerization.

18. The aqueous polymer dispersion according to claim 1 or 2, further comprising a film-forming aid.

19. A process for preparing an aqueous polymer dispersion according to any one of claims 1 to 18, comprising a free-radical aqueous emulsion polymerization of the monomers M, wherein the aqueous emulsion polymerization is carried out at least partly in the presence of a chain transfer compound.

20. The process according to claim 19, wherein the free-radical aqueous emulsion polymerization is carried out as a free-radical aqueous multistage emulsion polymerization as defined in any one of claims 14 to 17.

21. Use of the aqueous polymer dispersion according to any one of claims 1 to 18 as binder or cobinder in aqueous coating compositions and in coating compositions for shaped mineral bodies.

22. Use of the aqueous polymer dispersion according to any one of claims 1 to 18 as a binder or co-binder in an architectural coating composition.

23. An aqueous coating composition comprising the aqueous polymer dispersion of any one of claims 1 to 18.

24. A method of producing a permanent coating on a surface comprising (a) applying the coating composition according to claim 23 to a surface, and (b) drying the coating composition to produce a permanent coating.

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