Aqueous polymer latex of film-forming copolymer suitable as binder in aqueous coating compositions

Abstract

The invention relates to aqueous polymer latexes of film-forming copolymers obtainable by aqueous emulsion polymerization of ethylenically unsaturated monomers M comprising a combination of methylene-gamma-butyrolactone and (meth) acrylate. The invention also relates to a process for producing such polymer latexes and to the use of these polymer latexes as binders in aqueous coating compositions. Furthermore, the present invention relates to an aqueous coating composition containing a binder polymer in the form of said aqueous polymer latex and at least one additional ingredient, which is conventionally used in aqueous coating compositions and is not a binder.

Description

[0001] This invention relates to aqueous polymer latexes of film-forming copolymers obtainable by aqueous emulsion polymerization of olefinically unsaturated monomers M, wherein these olefinically unsaturated monomers M comprise a combination of methylene-γ-butyrolactone and (meth)acrylate as monomers. The invention also relates to a method for producing such polymer latexes and to the use of these polymer latexes as binders in aqueous coating compositions. Furthermore, the invention relates to an aqueous coating composition containing a binder polymer in the form of an aqueous polymer latex as defined herein and at least one additional component that is conventionally used in aqueous coating compositions and is not a binder.

[0002] Polymer latexes, also known as polymer dispersions, are commonly known, particularly, as binders or binder components in coating compositions, also referred to as co-binders. As binders or co-binders in coating compositions, one of the important requirements is that they provide the coating with hardness and adhesion to the coated surface. Furthermore, polymer latexes should offer good opacity, good detergency, low dust accumulation, and low water absorption.

[0003] Despite progress in many areas, providing polymer dispersions with balanced application characteristics remains a challenging task, as both application properties and the stability of the polymer dispersion must be considered. In particular, it is difficult to simultaneously reconcile different coating property requirements using binders. Often, attempts to improve one property of the coating by varying the polymer composition of the binder result in a significant deterioration of other properties of the coating.

[0004] While the polymer dispersions described in this art have particular advantages in one or more respects, they do not always possess a well-balanced set of characteristics. Furthermore, they are based solely on monomers prepared from fossil sources. Given the ongoing discussions regarding the impact of CO2 emissions, there is a need to at least partially replace fossil fuels with bio-based carbon in polymer latexes. The term bio-based means that the monomers are prepared at least partially from renewable raw materials such as plants, plant parts, plant waste, biomass, etc. These products are referred to as bio-based and are characterized by traceability. 14 C carbon content. It is also possible to convert these materials into suitable feedstocks, such as bio-naphtha, as described, for example, in EP 2 290 045 A1 or EP 2290 034 A1. Such feedstocks typically enter chemical production systems, such as steam crackers, where they are converted along the chemical value chain into products such as acrylic acid, methacrylic acid, acrylates, methacrylates, etc. The renewable material content of these products is determined by mass balance and can be allocated to these products.

[0005] WO 2014 / 207389 describes the use of 2-octyl acrylate from renewable resources in the production of a polymer latex. The polymer latex is suggested as an adhesive. However, a large amount of 2-octyl acrylate in the monomers forming the latex will lead to a low glass transition temperature of the resulting polymer, as homopolymers of 2-octyl acrylate have a glass transition temperature below -40 °C. Therefore, a latex with a suitable glass transition temperature will require a considerable amount of conventional fossil-based monomers.

[0006] WO 2018 / 118221 describes a copolymer latex comprising monomers with a high biorenewable carbon content, the homopolymers of which have a high glass transition temperature, in particular isobornyl methacrylate. However, isobornyl methacrylate can cause problems during emulsion polymerization and can lead to unstable polymer latexes (see e.g. O. Llorente et al. Progress in Organic Coatings 172 (2022) 107137).

[0007] WO 2022 / 018013 describes a polymer latex based on acrylate monomers, methacrylate monomers and / or monovinyl aromatic monomers, which contains an amount of monomers selected from isobutyl acrylate and isopentyl acrylate and mixtures thereof. Coating compositions prepared therefrom result in coatings with improved coating properties such as resistance to whitening, water absorption and flexibility of the coating. Isobutyl acrylate and isopentyl acrylate can - at least as far as their alkyl alcohol moieties are concerned - be obtained from biological sources and thus allow for a reduction of fossil carbon in the polymer latex.

[0008] JP 2022083035 and JP 2022140384 describe copolymers of an a-methylene lactone, such as a-methylene valerolactone or a-methylene-γ-butyrolactone, with a methacrylate, such as benzyl methacrylate and methyl methacrylate, which are prepared by aqueous suspension polymerization followed by filtration of the polymer from the aqueous polymerization mixture. No stable latex is obtained and the polymers are not suitable as adhesives for coating aqueous coating compositions.

[0009] However, there is still a need to provide polymer latices which are at least partially based on bio-based monomers and which have acceptable or improved application characteristics which make them suitable as adhesives in aqueous coating compositions, in particular for aqueous coating compositions for external and internal application.

[0010] It has surprisingly been found that polymer latexes based on an amount of monomer M1 which is a methylene-gamma-butyrolactone and in particular alpha-methylene-gamma-butyrolactone in combination with other conventional or bio-based monomers M2 as defined herein improve the coating properties, i.e. hardness, wet and dry adhesion to coated surfaces, in particular adhesion of the coating to surfaces previously coated with alkyd resins (alkyd adhesion), gloss and dust pick-up, of coating compositions, in particular aqueous coating compositions, without deteriorating other properties such as spreading rate (opacity), wet intercoat adhesion and dry intercoat adhesion and stain removal properties. Furthermore, monomer M1 can be obtained from biological sources and thus allows to reduce fossil carbon in the polymer latex.

[0011] The present invention thus relates to an aqueous polymer latex of a copolymer obtainable by aqueous emulsion polymerization of ethylenically unsaturated monomers M, which comprise

[0012] i. 2 to 70 % by weight, in particular 5 to 65 % by weight, preferably 10 to 60 % by weight, especially 5 to 40 % or 10 to 40 % by weight, based on the total amount of monomers M, of monomer M1 which is a methylene-gamma-butyrolactone and in particular alpha-methylene-gamma-butyrolactone;

[0013] ii. 20 to 95 % by weight, in particular 20 to 90 % or 20 to 85 % by weight, especially 30 to 80 % by weight, based on the total amount of monomers M, of at least one monomer M2 selected from the group consisting of C2-C 20 alkyl esters of acrylic acid and C5-C 20 alkyl esters of methacrylic acid and mixtures thereof;

[0014] iii. 0 to 40 % by weight, in particular 0 to 35 % by weight, especially 0 to 30 % by weight, based on the total amount of monomers M, of one or more monomers M3 selected from the group consisting of tert-butyl acrylate, C1-C4-alkyl esters of methacrylic acid, cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate and monovinyl aromatic monomers and mixtures thereof;

[0015] wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, in particular in the range of 10 to 65 % by weight, and especially in the range of 15 to 60 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, based on the total amount of ethylenically unsaturated monomers M.

[0016] The present application also relates to a process for producing the aqueous polymer latex of the present application. The process comprises carrying out an aqueous emulsion polymerization of monomers M.

[0017] The present application also relates to the use of these polymer latices as binders in aqueous coating compositions.

[0018] Furthermore, the present application relates to an aqueous coating composition, which contains

[0019] a) a binder polymer in the form of an aqueous polymer latex as defined herein; and

[0020] b) at least one further ingredient which is conventionally used in aqueous coating compositions and is not a binder, in particular at least one of an inorganic pigment and an inorganic filler.

[0021] The present application is associated with several benefits.

[0022] • the polymer latices are stable and provide good and well-balanced application characteristics to the aqueous coating compositions, such as improved hardness, improved adhesion properties such as high alkyd adhesion in wet and dry state, improved gloss, reduced dust pick-up, good spread rate (opacity), high intercoat adhesion and good stain removal properties.

[0023] • due to the polymer latices containing considerable amounts of monomers M1, M2 and M3, at least in terms of monomers M1 and also some of monomers M2 and M3, which can be obtained from biorenewable sources, they allow for a significant reduction of the need for fossil carbon, in particular by at least 10%, especially by at least 25% or even by at least 40%, such as 55%, and up to 100%. The incorporation of biogenic carbon and the reduction of fossil carbon can reduce the carbon footprint of the polymer latices.

[0024] Due to their well-balanced application characteristics, the polymer latices are particularly useful as binders in aqueous architectural coatings and have beneficial properties in aqueous primer and aqueous topcoat formulations as well as in exterior and interior architectural paints.

[0025] Herein and throughout the specification, the term "biobased monomer" means that the respective monomer is at least partially produced from molecules obtained from biorenewable resources such as biomass. Such molecules are characterized by a biogenic carbon content of at least 90 mol-%, preferably at least 95 mol-%, such as 100 mol-%, based on the total amount of carbon atoms.

[0026] The term "biogenic carbon" indicates that the carbon is of biological origin and comes from biological material / renewable resources. Herein and in the following, renewable origin and biorenewable origin are used synonymously and refer to a source of biological origin other than fossil origin. The content of biogenic carbon and the content of biological material are expressions indicating the same value. A material of renewable origin or biological material is an organic material, wherein the carbon comes from CO2 fixed by photosynthesis from the atmosphere in recent times (on a human scale). Biological material (100% carbon of natural origin) has a content of isotopic −12 , typically about 1.2 x 10 −12 , while the isotopic ratio of fossil materials is zero. In fact, the isotopic 14 C / 12 C is formed in the atmosphere and then integrated via photosynthesis on a time scale of up to several decades. 14 The half-life of isotopic 14 C is 5,730 years. Therefore, materials from photosynthesis, i.e. usually plants, necessarily have a maximum content of isotopic n C. The determination of the content of biological material or biogenic carbon can be carried out according to the standards ASTM D6866-12, Method B (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04).

[0027] Herein and throughout the specification, the term "(meth)acryloyl" includes both acryloyl and methacryloyl. Thus, the term "(meth)acrylate" includes acrylate and methacrylate, and the term "(meth)acrylamide" includes acrylamide and methacrylamide.

[0028] Herein and throughout the specification, the term "aqueous coating composition" means a liquid aqueous coating composition containing water in an amount sufficient to achieve flowability as a continuous phase.

[0029] Herein and throughout the specification, the terms "wt.-%" and "% b.w." are used synonymously.

[0030] Herein and throughout the specification, the term "pphm" means parts per hundred of monomers, i.e. parts by weight per 100 parts of monomers, and corresponds to the relative amount by weight of a certain substance based on the total amount of monomers M.

[0031] Throughout this document and the entire specification, the term "ethylenically unsaturated monomer" is to be understood as meaning that the monomer has at least one C=C double bond, for example 1, 2, 3 or 4 C=C double bonds, which are free-radically polymerizable, i.e. which polymerize under the conditions of an aqueous free-radical emulsion polymerization process to give a polymer having a carbon atom main chain. Throughout this document and the entire specification, the term "monoethylenically unsaturated" is to be understood as meaning that the monomer has a single C=C double bond, which is readily free-radically polymerizable under the conditions of an aqueous free-radical emulsion polymerization.

[0032] Throughout this document and the entire specification, the terms "ethoxylated" and "polyethoxylated" are used synonymously and refer to compounds having an oligomeric or polyoxyethylene group formed from repeating units O-CH2CH2. In this context, the term "degree of ethoxylation" refers to the number average of repeating units O-CH2CH2in these compounds.

[0033] Throughout this document and the entire specification, the term "nonionic" in the context of compounds, in particular monomers, means that the respective compound does not carry any ionic functional groups or any functional groups which can be converted into ionic groups by protonation or deprotonation.

[0034] Throughout this document and the entire specification, the prefix C n -C m each indicates the range of possible numbers of carbon atoms which a molecular moiety or compound can have. The term "C1-C n alkyl" denotes a group which is a straight-chain or branched saturated hydrocarbon group having 1 to n carbon atoms. The term "C n / C m alkyl" denotes a mixture of two alkyl groups, one having n carbon atoms and the other having m carbon atoms.

[0035] For example, the term C1-C 20 alkyl" denotes a group which is a straight-chain or branched saturated hydrocarbon group having 1 to 20 carbon atoms, while the term C1-C4 alkyl" denotes a group which is a straight-chain or branched saturated hydrocarbon group having 1 to 4 carbon atoms, and C5-C 20Alkyl denotes a radical of a straight-chain or branched saturated hydrocarbon group having 5 to 20 carbon atoms. Examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl, t-butyl, 2-methylpropyl (i-propyl), 1,1 -dimethylethyl (t-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, n-heptyl, 2-heptyl, n-octyl, 2-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.

[0036] The term "cyclopentyl" as used herein refers to a monocyclic alicyclic radical having 5 carbon atoms, which is unsubstituted or substituted by 1, 2, 3 or 4 methyl groups and which is in particular unsubstituted.

[0037] The term "cyclohexyl" as used herein refers to a monocyclic alicyclic radical having 6 carbon atoms, which is unsubstituted or substituted by 1, 2, 3 or 4 methyl groups and which is in particular unsubstituted.

[0038] The term "isobornyl" refers to the radical 1,7,7-trimethylbicyclo[2.2.1]heptyl.

[0039] According to the present application, the monomers M comprise a monomer M1 which is a methylene-gamma-butyrolactone and in particular alpha-methylene-gamma-butyrolactone. Methylene-gamma-butyrolactones such as alpha-methylene-gamma-butyrolactone have an exocyclic double bond which is susceptible to free radical polymerization. In particular, the monomer M1 is alpha-methylene-gamma-butyrolactone which has a high reactivity, but despite its hydrolytically unstable lactone structure, it can surprisingly be subjected to emulsion polymerization without forming ring-opening side products. Here and in the following, alpha-methylene-gamma-butyrolactone is also referred to as 2-methylene-gamma-butyrolactone or 3-methylenoxolane-2-one.

[0040] The total amount of monomers M1 is 2 to 70 % by weight, in particular 5 to 65 % by weight or 10 to 60 % by weight, preferably 10 to 50 % by weight, especially 5 to 40 % by weight or 10 to 40 % by weight, more specifically 10 to 35 % by weight or 10 to 30 % by weight, based on the total weight of monomers M.

[0041] Methylene-gamma-butyrolactones such as alpha-methylene-gamma-butyrolactone are commercially available. They are preferably bio-based, i.e. they can be obtained from biological sources. For example, alpha-methylene-gamma-butyrolactone is a naturally occurring compound and is known as Tulipalin A. Alpha-methylene-gamma-butyrolactone can be produced from tetrahydro-3-furoic acid as described in US 6,362,346.

[0042] Alpha-methylene-gamma-butyrolactone can also be produced from itaconic acid by the method described in PCT / EP2022 / 077180, which is incorporated herein by reference. This method comprises the enzymatic reduction of itaconic acid to 2-methylene-4-hydroxybutyric acid, which spontaneously internal lactonizes to 2-methylene-gamma-butyrolactone. This method comprises the enzymatic production of itaconyl-CoA, for example by using an acyl-CoA synthetase or a CoA transferase, followed by reaction with an oxidoreductase (e.g. an acyl-CoA reductase), thereby forming itaconic semialdehyde. Alternatively, itaconic semialdehyde can be obtained directly from itaconic acid by reaction with a carboxylate reductase. Itaconic semialdehyde is then reacted with an oxidoreductase, in particular an alcohol dehydrogenase or a 3-sulfooxy lactal reductase, to obtain 2-methylene-4-hydroxybutyric acid, which spontaneously forms alpha-methylene-gamma-butyrolactone. In some cases, additional enzymes for lactonization can be needed, for example a thioesterase or a lactonase. For example, depending on the enzyme used in the first step, 2-methylene-4-hydroxybutyric acid CoA can be obtained. In this case, 2-methylene-4-hydroxybutyric acid CoA will react with a thioesterase to obtain alpha-methylene-gamma-butyrolactone. The starting material itaconic acid can be produced by biotechnological methods from carbohydrates like glucose or glucose-containing raw materials. An overview is given by M. Okabe et al. in Biotechnological Production of Itaconic Acid and its Biosynthesis from Aspergillus terreus in Applied Microbiology and Biotechnology 84 (4), 2009, S. 597-606. and Garabed Antranikian: Angewandte Mikrobiologie, Springer-Verlag, Berlin / Heidelberg 2006, ISBN 3-540-24083-7, pp. 351-352.

[0043] It is preferred that the methylene-y-butyrolactone is a-b-methylene-y-butyrolactone, which is bio-based and preferably has a bio-carbon content of at least 90 mol-%, in particular at least 95 mol-% or at least 98 mol-%, for example 100 mol-%, based on the total amount of carbon atoms thereof. Thus, a particular embodiment of the present application relates to a polymer latex as defined herein, wherein at least 90 mol-%, preferably at least 95 mol-% or at least 98 mol-%, for example 100 mol-%, of the carbon atoms of the monomer M1 are of biological origin.

[0044] The monomers M2 and M3 can also be bio-based monomers, in particular if the monomers M2 and M3 are esters of acrylic acid or methacrylic acid. In this case, the alcohol part of the ester can be bio-based. For example, bio-based ethanol, isobutanol, 2-methylbutanol, isoamyl alcohol / isopentanol, 2-octanol, cyclopentanol or isobornyl alcohol having a bio-carbon content of at least 90 mol-%, preferably at least 95 mol-% or at least 98 mol-%, for example 100 mol-%, based on the total amount of carbon atoms thereof, are readily available on a large scale.

[0045] The acrylic acid and / or methacrylic acid used for esterification can be obtained from fossil sources according to standard procedures. Acrylic acid can also be prepared from renewable feedstocks, for example according to WO 2006 / 092272 or DE 10 2006 039 203 A or EP 2 922 580.

[0046] Thus, the monomers M2 and M3 can have a bio-carbon content of preferably at least 30 mol-%, in particular at least 40 mol-%, based on the total amount of carbon atoms in the monomers M2 and M3, respectively. By using monomers M2 and M3, if present, which are at least partially of biological origin, the demand for fossil carbon in the polymer latex can be significantly reduced. In particular, an amount of at least 10 mol-%, in particular at least 15 mol-% or at least 20 mol-% or more, for example at least 30 mol-% or at least 40 mol-% or at least 50 mol-% or more, of carbon of biological origin in the latex can be achieved.

[0047] In addition to the monomer M1, the monomers M of the latex-forming polymer comprise one or more monomers M2 as defined above.

[0048] Suitable monomers M2 are selected from the group consisting of:

[0049] • C2-C10-alkyl esters of acrylic acid other than tert-butyl acrylate 20-Alkyl esters, including but not limited to ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, isodecyl acrylate, 2-propylheptyl acrylate, lauryl acrylate, C-acrylate 12 / C 14 -Alkyl ester, C-acrylate 12 -C 15 -Alkyl ester, isotridecyl acrylate, C-acrylate 17 -Alkyl ester, C-acrylate 16 / C 18 -Alkyl esters and stearyl acrylate;

[0050] • C5-C of methacrylic acid 20 α-alkyl esters, including but not limited to n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, 2-octyl methacrylate, 2-ethylhexyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, 2-propylheptyl methacrylate, lauryl methacrylate, and C-methacrylate. 12 / C 14 -Alkyl ester, C-methacrylic acid 12 -C 15 -Alkyl ester, isotridecyl methacrylate, C-methacrylate 17 -Alkyl ester, C-methacrylic acid 16 / C 18 -Alkyl esters and stearyl methacrylate; and

[0051] • Its mixture.

[0052] Preferably, monomer M2 is selected from the group consisting of ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, and mixtures thereof. Preferably, monomer M2 comprises at least one of n-butyl acrylate, 2-ethylhexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-octyl acrylate, isoamyl acrylate (= 3-methylbutyl acrylate; isoamyl acrylate), 2-methylbutyl acrylate, and isobutyl acrylate, or mixtures thereof. Ethyl acrylate, isoamyl acrylate, 2-methylbutyl acrylate, isobutyl acrylate, n-heptyl acrylate, n-octyl acrylate, and 2-octyl acrylate can be produced from fossil sources or can be at least partially biobased. In particular, the ethyl, isoamyl, 2-methylbutyl, isobutyl, n-heptyl, n-octyl, and 2-octyl moieties of ethyl acrylate, isoamyl acrylate, 2-methylbutyl acrylate, isobutyl acrylate, n-heptyl acrylate, n-octyl acrylate, and 2-octyl acrylate, respectively, are biobased, i.e. these monomers are obtained from esterification of acrylic acid (which can be biobased or of fossil origin) with biobased ethanol, isoamyl alcohol, 2-methylbutanol, isobutanol, n-heptanol, n-octanol, or 2-octanol, respectively.

[0053] In a preferred embodiment group, monomer M2 comprises isobutyl acrylate, in particular biobased isobutyl acrylate. In particular, monomer M2 is isobutyl acrylate, in particular biobased isobutyl acrylate. In this preferred embodiment group, monomer M2 can also be isobutyl acrylate together with at least one further acrylic C2-C8 alkyl ester different from isobutyl acrylate. 10 Mixtures of alkyl acrylates such as n-butyl acrylate, isoamyl acrylate, 2-methylbutyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-octyl acrylate, and 2- ethylhexyl acrylate.

[0054] In the context of this embodiment group, it is preferred that the amount of isobutyl acrylate is in the range of 20 to 90 % by weight or 20 to 85 % by weight, in particular 25 to 80 % by weight or 30 to 80 % by weight, more particularly 35 to 80 % by weight, specifically 40 to 80 % by weight, and more specifically 50 to 80 % by weight, based on the total amount of monomers M.

[0055] Acrylates such as isobutyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate and 2-octyl acrylate are typically produced by esterification of acrylic acid with the respective alcohol such as isobutyl alcohol (2-methylpropan-1-ol), 2-methylbutan-1-ol, isoamyl alcohol (3-methylbutan-1-ol; isoamyl alcohol) or 2-octanol, respectively, or, especially in the case of acrylates derived from higher alcohols, by trans-esterification of methyl acrylate or ethyl acrylate with the respective alcohol such as isobutyl alcohol (2-methylpropan-1-ol), 2-methylbutan-1-ol, isoamyl alcohol (3-methylbutan-1-ol) or 2-octanol, respectively.

[0056] Isobutyl alcohol, 2-methylbutan-1-ol and isoamyl alcohol, and mixtures thereof, can be produced on a large scale by fermentation from a variety of renewable feedstocks, including corn, wheat, sorghum, barley, and sugar cane, in particular from cellulose-containing raw materials and thus from biological sources or renewable raw materials. In particular, fermentation can produce a mixture comprising different alkanols, from which isobutyl alcohol, 2-methylbutan-1-ol and 3-methylbutan-1-ol can be separated by conventional techniques such as fractional distillation. Thereby, pure alcohols (purity > 90%) can be obtained, or mixtures containing a total amount of at least 80%, in particular at least 90%, of at least two alcohols selected from the group consisting of isobutyl alcohol, 2-methylbutan-1-ol and 3-methylbutan-1-ol can be obtained. For example, mixtures comprising at least 80% by weight of a mixture of 2-methylbutanol and 3-methylbutanol and up to 20% by weight of isobutyl alcohol can be used for esterification or trans-esterification. In the mixture, the molar ratio of 3-methylbutanol to 2-methylbutan-1-ol can vary, for example, from 1 : 10 to 10 : 1 and in particular in the range of 1 : 1 to 10 : 1. 2-Octanol can be produced by base-catalyzed thermal cleavage of ricinoleic acid, wherein sebacic acid is produced as a by-product. Castor oil, which consists mainly of ricinoleic acid, is the main raw material. Thus, the inclusion of these monomers M2 into the polymer latex significantly increases the amount of biogenic carbon in the polymer latex. The incorporation of biogenic carbon and the reduction of fossil carbon can reduce the carbon footprint of the polymer latex.

[0057] Thus, specific embodiments of the present application relate to a polymer latex as defined herein, wherein the carbon atoms of at least isobutyl, 2-methylbutyl, isoamyl and 2-octyl, respectively, in monomer M2, in particular the carbon atoms of at least isobutyl in monomer M2, are of biological origin, i.e. they are at least partially made from biogenic carbon. In particular, isobutanol, 2-methylbutan-1-ol, 3-methylbutanol and 2-octanol, respectively, used for the production of monomer M2, preferably have a biogenic carbon content of at least 90 mol-%, based on the total amount of carbon atoms in isobutanol, 2-methylbutanol, 3-methylbutanol and 2-octanol, respectively. This content is advantageously higher, in particular greater than or equal to 95 mol-%, preferably greater than or equal to 98 mol-% and advantageously equal to 100 mol-%. Similarly, acrylic acid can be produced from renewable materials. However, to date, acrylic acid produced from biological materials is not available on a large scale. Thus, monomer M2 has a biogenic carbon content of preferably at least 51 mol-%, in particular at least 54 mol-% and especially at least 57 mol-%, based on the total amount of carbon atoms in isobutyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate and 2-octyl acrylate, respectively. By using monomer M2 which is at least partially of biological origin, the demand for fossil carbon in the polymer latex can be significantly reduced. In particular, an amount of at least 10 mol-%, in particular at least 15 mol-% or at least 20 mol-% or more, e.g. 30 mol-% or 40 mol-% or more, of carbon of biological origin can be achieved.

[0058] The total amount of monomer M2 is 20 to 95 % by weight, or 20 to 90 % by weight, in particular 30 to 85 % by weight, or 30 to 80 % by weight, or 35 to 80 % by weight, especially 40 to 80 % by weight, and more specifically 50 to 80 % by weight, based on the total weight of monomers M.

[0059] In addition to monomers M1 and M2, the monomers M of which the latex-forming polymer is formed can comprise one or more monomers M3 as defined above.

[0060] Suitable monomers M3 are selected from the group consisting of:

[0061] C1-C4-alkyl esters of methacrylic acid, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate and t-butyl methacrylate;

[0062] t-butyl acrylate;

[0063] cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate;

[0064] - vinyl aromatic monomers, such as styrene, 2-methylstyrene, 4-methylstyrene; and

[0065] - mixtures thereof.

[0066] In a preferred embodiment group, the monomers M3 are selected from the group consisting of:

[0067] - Ci-C4-alkyl esters of methacrylic acid, in particular methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate and tert-butyl methacrylate;

[0068] - tert-butyl acrylate;

[0069] - cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate;

[0070] - styrene; and

[0071] - mixtures thereof.

[0072] In this group, the monomers M3 are in particular selected from the group consisting of:

[0073] - methyl methacrylate, n-butyl methacrylate;

[0074] - tert-butyl acrylate;

[0075] - cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate;

[0076] - styrene; and

[0077] - mixtures thereof.

[0078] In the specific embodiment group (M3-A), the monomers M3 comprise methyl methacrylate in an amount of at least 50% by weight, in particular at least 80% by weight or 100% by weight, based on the total amount of monomers M3 in monomers M. In this group, more particularly, the monomers M3 are selected from the group consisting of methyl methacrylate and combinations of methyl methacrylate with n-butyl methacrylate, tert-butyl acrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate or with styrene.

[0079] In this specific embodiment group M3-A, it is preferred that the monomers M3 are methyl methacrylate.

[0080] In the context of the embodiment group M3-A, it is preferred that the amount of methyl methacrylate, if present in monomers M, is in the range of 1 to 40% by weight, in particular 1.5 to 35% by weight, in particular 2 to 30%, more particularly 10 to 20% by weight, based on the total amount of monomers M.

[0081] In another particular embodiment group (M3-B), monomers M3 comprise styrene in an amount of at least 50% by weight, in particular at least 80% by weight, or 100% by weight, based on the total amount of monomers M3 in monomers M. In this group, more particularly, monomers M3 are selected from the group consisting of styrene and combinations of styrene with methyl methacrylate, n-butyl methacrylate, t-butyl acrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, or isobornyl methacrylate.

[0082] In this particular embodiment group M3-B, it is preferred that monomers M3 are styrene.

[0083] In the context of embodiment group M3-B, it is preferred that the amount of styrene is in the range of 1% to 30%, in particular 1.5% to 25%, especially 2% to 20% by weight, based on the total amount of monomers M.

[0084] The total amount of monomers M3 is 0% to 40%, in particular 0% to 35% or 1% to 35% by weight, in particular 0% to 30% or 2% to 30% by weight, more particularly 0% to 20% or 10% to 20% by weight, based on the total weight of monomers M.

[0085] The total amount of monomers M1 and M3 is preferably in the range of 5% to 70% by weight, in particular in the range of 10% to 65% by weight, especially in the range of 15% to 60% by weight, based on the total amount of ethylenically unsaturated monomers M.

[0086] The total amount of monomers M1, M2 and M3 is at least 85% by weight, in particular at least 90% by weight, especially at least 95% by weight, based on the total amount of ethylenically unsaturated monomers M.

[0087] The weight ratio of M1 to M2 is typically in the range of 1 : 10 to 10 : 1, in particular 1 : 5 to 5 : 1, preferably in the range of 1 : 5 to 4 : 1, especially in the range of 1 : 5 to 3.5 : 1, more particularly in the range of 1 : 5 to 1 : 1, and even more particularly in the range of 1 : 5 to 1 : 2.

[0088] If M3 is present, the weight ratio of M1 to M3 is typically in the range of 1 : 5 to 30 : 1, in particular 1 : 4 to 25 : 1, preferably in the range of 1 : 2 to 20 : 1.

[0089] Monomers M can further comprise at least one monomer M4 selected from monoethylenically unsaturated monomers having an acidic group.

[0090] Suitable monomers M4 include, but are not limited to

[0091] - monoethylenically unsaturated mono- or dicarboxylic acids having 3 to 6 carbon atoms, such as acrylic acid, methacrylic acid, crotonic acid, 2-ethylacrylic acid, 2-propylacrylic acid, 2-acryloyloxyacetic acid and 2-methacryloyloxyacetic acid;

[0092] - monoethylenically unsaturated dicarboxylic acids having 4 to 6 carbon atoms, such as itaconic acid, citraconic acid and fumaric acid;

[0093] - half-esters of monoethylenically unsaturated dicarboxylic acids having 4 to 6 carbon atoms with Ci-C4-alkanols, such as methanol or ethanol, such as the half-esters of itaconic acid, citraconic acid, maleic acid or fumaric acid with methanol or ethanol;

[0094] - monoethylenically unsaturated sulfonic acids, such as vinylsulfonic acid, allylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid,

[0095] - monoethylenically unsaturated phosphonic acids, such as vinylphosphonic acid, allylphosphonic acid, styrenephosphonic acid and 2-acrylamido-2-methylpropanephosphonic acid,

[0096] - monoethylenically unsaturated phosphoric acids, such as the monophosphoric acid esters of hydroxyalkyl acrylates, of hydroxyalkyl methacrylates, of alkoxylated hydroxyalkyl acrylates and of alkoxylated hydroxyalkyl methacrylates, in particular the monophosphoric acid esters of hydroxyethyl acrylate, of hydroxypropyl acrylate or of hydroxybutyl acrylate, of hydroxyethyl methacrylate, of hydroxypropyl methacrylate or of hydroxybutyl methacrylate, of ethoxylated hydroxy-C2-C4-alkyl acrylates, of propoxylated hydroxy-C2-C4-alkyl acrylates, of ethoxylated hydroxy-C2-C4-alkyl methacrylates and of propoxylated hydroxy-C2-C4-alkyl methacrylates.

[0097] The monomers M4 mentioned above can be present in their acidic form or in the form of their salts, in particular in the form of their alkali metal or ammonium salts.

[0098] Among the monomers M4 mentioned above, preference is given to monoethylenically unsaturated monocarboxylic acids, monoethylenically unsaturated dicarboxylic acids and monoethylenically unsaturated sulfonic acids and salts thereof, in particular alkali metal salts and ammonium salts. Particular preference is given to acrylic acid, methacrylic acid, itaconic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof, in particular alkali metal salts and ammonium salts, and combinations thereof. More preference is given to monoethylenically unsaturated monocarboxylic acids and monoethylenically unsaturated sulfonic acids and salts thereof, in particular alkali metal salts and ammonium salts, in particular acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropane sulfonic acid, salts thereof, in particular alkali metal salts and ammonium salts, and mixtures of the monomers mentioned above. In a particular embodiment group, the monomer M4 comprises methacrylic acid. In particular, the monomer M4 is methacrylic acid or a mixture of acrylic acid and methacrylic acid. In another particular embodiment group, the monomer M4 comprises acrylic acid. In another particular embodiment group, the monomer M4 comprises 2-acrylamido-2-methylpropane sulfonic acid or a salt thereof, in particular an alkali metal salt or an ammonium salt. In particular, the monomer M4 is 2-acrylamido-2-methylpropane sulfonic acid or a salt thereof, in particular an alkali metal salt or an ammonium salt, or a mixture of acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid or a salt thereof, in particular an alkali metal salt or an ammonium salt. In another particular embodiment, the monomer M4 is acrylic acid.

[0099] The total amount of monomers M4 is 0.05 to 5 % by weight or 0.1 to 4 % by weight, in particular 0.05 to 3.5 % by weight or 0.1 to 3 % by weight, especially 0.2 to 3 % by weight or 0.5 to 3 % by weight or 0.5 to 2 % by weight, based on the total amount of monomers M.

[0100] The monomers M can further comprise at least one monoethylenically unsaturated non-ionic monomer M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar.

[0101] Suitable monomers M5 are selected from the group consisting of non-ionic monoethylenically unsaturated monomers having a functional group selected from the group consisting of hydroxyalkyl groups, in particular hydroxy-C2-C4-alkyl groups, primary carboxamide groups, urea groups, ketone groups and combinations thereof.

[0102] The total amount of monomers M5 will typically not exceed 10 % by weight, in particular 7 % by weight, based on the total amount of monomers M. In particular, the total amount of monomers M5, if present, is typically 0 to 9.95 % by weight, 0.05 to 9.95 % by weight, in particular 0.1 to 7 % by weight, especially 0.1 to 5 % by weight or 0.1 to 4 % by weight or 0.5 to 3 % by weight or 1 to 3 % by weight or 0.5 to 2 % by weight, based on the total weight of monomers M.

[0103] Examples of monomers M5 having a formamide group (monomers M5a hereinafter) include, but are not limited to, primary amides of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, such as acrylamide and methacrylamide, and Ci-C4-alkyl amides of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms, such as N-methyl acrylamide, N-ethyl acrylamide, N-propyl acrylamide, N-isopropyl acrylamide, N-butyl acrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, N-propyl methacrylamide, N-isopropyl methacrylamide, and N-butyl methacrylamide. Most preferably, monomers M5a are selected from acrylamide and methacrylamide.

[0104] Examples of monomers M5 having a urea group (monomers M5b hereinafter) are Ci-C4-alkyl esters of acrylic or methacrylic acid and N-Ci-C4-alkyl amides of acrylic or methacrylic acid, wherein the Ci-C4-alkyl group carries a urea group or a 2-oxoimidazolidinyl group, such as 2-(2-oxo-imidazolidin-1-yl)ethyl acrylate, 2-(2-oxo-imidazolidin-1-yl)ethyl methacrylate, which are also known as 2-ureidoacrylate and 2-ureido methacrylate, respectively, N-(2-acryloyloxyethyl)urea, N-(2-methacryloyloxyethyl)urea, N-(2-(2-oxo-imidazolidin-1-yl)ethyl)acrylamide, N-(2-(2-oxo-imidazolidin-1-yl)ethyl)methacrylamide, and allyl- or vinyl-substituted ureas and allyl- or vinyl-substituted 2-oxoimidazolines, such as 1-allyl-2-oxoimidazoline, N-allylurea, and N-vinylurea.

[0105] Examples of monomers M5 having a ketone group (monomers M5c hereinafter) are

[0106] • C2-C8-oxoalkyl esters of acrylic or methacrylic acid and N-C2-C8-oxoalkyl amides of acrylic or methacrylic acid, such as diketone acrylamide (DAAM) and diketone methacrylamide, and

[0107] • Ci-C4-alkyl esters of acrylic or methacrylic acid and N-Ci-C4-alkyl amides of acrylic or methacrylic acid, wherein the Ci-C4-alkyl group carries a 2-acetyloxyacetyl group having the formula O-C(=0)-CH2-C(=0)-CH3 (also known as acetoacetoxy), such as acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, acetoacetoxybutyl methacrylate, and 2-(acetoacetoxy)ethyl methacrylate.

[0108] Preferably, the monomers M comprise or consist of

[0109] i. methylene-gamma-butyrolactone, in particular alpha-methylene-gamma-butyrolactone, as monomer M1 in an amount of 5 to 70 % by weight, in particular 10 to 65 % by weight or 10 to 60 % by weight, preferably 10 to 50 % by weight, in particular 5 to 40 % by weight or 10 to 40 % by weight, more specifically 10 to 35 % by weight or 10 to 30 % by weight, based on the total amount of monomers M;

[0110] ii. at least one monomer M2 comprising isobutyl acrylate or being isobutyl acrylate in an amount of 20 to 90 % by weight, in particular 30 to 80 % by weight or 35 to 80 % by weight, in particular 40 to 80 % by weight, and more specifically 50 to 80 % by weight, based on the total amount of monomers M;

[0111] iii. at least one monomer M3 comprising methyl methacrylate, styrene or a combination thereof or being selected from the group consisting of methyl methacrylate, styrene or a combination thereof in an amount of 0 to 40 % by weight or 1 to 40 % by weight, in particular 0 to 35 % by weight or 1 to 35 % by weight, in particular 5 to 40 % by weight or 5 to 35 % by weight, based on the total amount of monomers M;

[0112] iv. one or more monoethylenically unsaturated monomers M4 selected from monoethylenically unsaturated monomers having an acidic group in an amount of 0.05 to 5 % by weight, or 0.1 to 4 % by weight, in particular 0.05 to 3.5 % by weight or 0.1 to 3 % by weight, in particular 0.2 to 3 % by weight or 0.5 to 3 % by weight, or 0.5 to 2 % by weight, based on the total amount of monomers M;

[0113] v. one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar in an amount of 0 to 9.95 % by weight, 0.05 to 9.95 % by weight, in particular 0.1 to 7 % by weight, in particular 0.1 to 5 % by weight or 0.1 to 4 % by weight or 0.5 to 3 % by weight or 1 to 3 % by weight or 0.5 to 2 % by weight, based on the total weight of monomers M, if present,

[0114] wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, in particular 10 to 65 % by weight, in particular 15 to 60 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, in particular at least 90 % by weight, in particular at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M.

[0115] In a first group of specific embodiments, the monomers M comprise or consist of:

[0116] i. 10 to 69.95 % by weight, in particular 15 to 64.85 % by weight, preferably 20 to 59.4 % by weight, in particular 10 to 40 % by weight, more specifically 15 to 35 % by weight or 20 to 30 % by weight, based on the total amount of monomers M, of an alpha-methylene-gamma-butyrolactone as monomer M1 ;

[0117] ii. 30 to 89.95 % by weight, in particular 35 to 84.85 % by weight, in particular 40 to 79.4 % by weight, based on the total amount of monomers M, of isobutyl acrylate as monomer M2;

[0118] iii. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, in particular 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from monoethylenically unsaturated monomers having an acidic group;

[0119] iv. 0 to 9.95 % by weight, 0.05 to 9.95 % by weight, in particular 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, based on the total weight of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar, if present,

[0120] wherein the total amount of monomers M1 and M2 is at least 85 % by weight, in particular at least 90 % by weight, in particular at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M;

[0121] or

[0122] i. 10 to 68.95 % by weight, in particular 15 to 63.35 % by weight, preferably 15 to 57.4 % by weight, in particular 15 to 40 % by weight, more specifically 15 to 35 % by weight or 15 to 30 % by weight, based on the total amount of monomers M, of an alpha-methylene-gamma-butyrolactone as monomer M1 ;

[0123] ii. 30 to 80 % by weight, in particular 35 to 75 % by weight, in particular 40 to 75 % by weight, based on the total amount of monomers M, of isobutyl acrylate as monomer M2;

[0124] iii. 1 to 35 % by weight, in particular 1.5 to 30 % by weight, especially 2 to 25 % by weight, based on the total amount of monomers M, of monomers M3 selected from the group consisting of methyl methacrylate, styrene and combinations thereof;

[0125] iv. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, especially 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from the group consisting of monoethylenically unsaturated monomers having acidic groups;

[0126] v. if present, 0 to 9.95 % by weight, 0.05 to 9.95 % by weight, in particular 0.05 to 5 % by weight, especially 0.1 to 4 % by weight, based on the total weight of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar,

[0127] wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, in particular in the range of 10 to 65 % by weight, especially in the range of 15 to 60 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, in particular at least 90 % by weight, especially at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M;

[0128] or

[0129] i. 10 to 68.95 % by weight, in particular 15 to 63.35 % by weight, preferably 15 to 57.4 % by weight, especially 15 to 40 % by weight, more specifically 15 to 35 % by weight or 15 to 30 % by weight, based on the total amount of monomers M, of an a-methylene-g-butyrolactone as monomer M1 ;

[0130] ii. 30 to 80 % by weight, in particular 35 to 75 % by weight, especially 40 to 75 % by weight, based on the total amount of monomers M, of monomers M2 which are isobutyl acrylate and at least one acrylic acid C2-C 10 mixtures of alkyl acrylates such as n-butyl acrylate, isopentyl acrylate, 2-methylbutyl acrylate, 2-octyl acrylate and 2-ethylhexyl acrylate;

[0131] iii. 1 to 35 % by weight, in particular 1.5 to 30 % by weight, especially 2 to 25 % by weight, based on the total amount of monomers M, of monomers M3 selected from the group consisting of methyl methacrylate, styrene and combinations thereof;

[0132] iv. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, especially 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from monoethylenically unsaturated monomers having acidic groups;

[0133] v. 0 to 9.95 % by weight, 0.05 to 9.95 % by weight, in particular 0.05 to 5 % by weight, especially 0.1 to 4 % by weight, based on the total weight of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar,

[0134] wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, in particular in the range of 10 to 65 % by weight, especially in the range of 15 to 60 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, in particular at least 90 % by weight, especially at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M.

[0135] In a specific embodiment group 1, the monomers M preferably comprise or consist of (embodiment group 1 a):

[0136] i. 10 to 69.95 % by weight, in particular 15 to 64.85 % by weight, preferably 20 to 59.4 % by weight, especially 15 to 40 % by weight, more specifically 15 to 35 % by weight or 20 to 30 % by weight, based on the total amount of monomers M, of an alpha-methylene-gamma-butyrolactone as monomer M1, wherein at least 90 mol-%, in particular at least 95 mol-%, especially at least 95 mol-% or 100 mol-% of the carbon atoms of the alpha-methylene-gamma-butyrolactone are of biological origin;

[0137] ii. 30 to 89.95 % by weight, in particular 35 to 84.85 % by weight, especially 40 to 79.4 % by weight, based on the total amount of monomers M, of isobutyl acrylate as monomer M2, wherein at least the carbon atoms of the isobutyl group in the isobutyl acrylate are of biological origin, in particular the bio-carbon content of the isobutyl methacrylate is at least 54 mol-%, in particular at least 57 mol-%;

[0138] iii. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, especially 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from monoethylenically unsaturated monomers having acidic groups;

[0139] iv. 0% to 9.95% by weight, 0.05% to 9.95% by weight, in particular 0.05% to 5% by weight, especially 0.1% to 4% by weight, based on the total amount of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20°C and 1 bar,

[0140] wherein the total amount of monomers M1 and M2 is at least 85% by weight, in particular at least 90% by weight, especially at least 95% by weight, based on the total amount of ethylenically unsaturated monomers M;

[0141] or

[0142] i. 10% to 68.95% by weight, in particular 15% to 63.35% by weight, preferably 15% to 57.4% by weight, especially 15% to 40% by weight, more specifically 15% to 35% by weight or 15% to 30% by weight, based on the total amount of monomers M, of an a-methylene-y-butyrolactone as monomer M1, wherein at least 90 mol-%, in particular at least 95 mol-%, especially at least 95 mol-% or 100 mol-% of the carbon atoms of the a-methylene-y-butyrolactone are of biological origin;

[0143] ii. 30% to 80% by weight, in particular 35% to 75% by weight, especially 40% to 75% by weight, based on the total amount of monomers M, of isobutyl acrylate as monomer M2, wherein at least the carbon atoms of the isobutyl group in the isobutyl acrylate are of biological origin, in particular the bio-carbon content of the isobutyl methacrylate is at least 54 mol-%, in particular at least 57 mol-%;

[0144] iii. 1% to 35% by weight, in particular 1.5% to 30% by weight, especially 2% to 25% by weight, based on the total amount of monomers M, of monomers M3 selected from the group consisting of methyl methacrylate, styrene and combinations thereof;

[0145] iv. 0.05% to 5% by weight, in particular 0.1% to 4% by weight, especially 0.5% to 3% by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from monoethylenically unsaturated monomers having an acidic group;

[0146] v. if present, 0% to 9.95% by weight, 0.05% to 9.95% by weight, in particular 0.05% to 5% by weight, especially 0.1% to 4% by weight, based on the total amount of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20°C and 1 bar,

[0147] wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, in particular in the range of 10 to 65 % by weight, especially in the range of 15 to 60 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, in particular at least 90 % by weight, especially at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M;

[0148] or

[0149] i. 10 to 68.95 % by weight, in particular 15 to 63.35 % by weight, preferably 15 to 57.4 % by weight, especially 15 to 40 % by weight, more specifically 15 to 35 % by weight or 15 to 30 % by weight, based on the total amount of monomers M, of an alpha-methylene-gamma-butyrolactone as monomer M1, wherein at least 90 mol-%, in particular at least 95 mol-%, especially at least 95 mol-% or 100 mol-% of the carbon atoms of the alpha-methylene-gamma-butyrolactone are of biological origin;

[0150] ii. 30 to 80 % by weight, in particular 35 to 75 % by weight, especially 40 to 75 % by weight, based on the total amount of monomers M, of monomers M2 which are isobutyl acrylate and at least one acrylic acid C2-C 10 a mixture of n-butyl acrylate, isoamyl acrylate, 2-methylbutyl acrylate, 2-octyl acrylate and 2-ethylhexyl acrylate, wherein at least the carbon atom of the iso-butyl group in the isobutyl acrylate is of biological origin, in particular the bio-carbon content of the isobutyl methacrylate is at least 54 mol-%, in particular at least 57 mol-%;

[0151] iii. 1 to 35 % by weight, in particular 1.5 to 30 % by weight, especially 2 to 25 % by weight, based on the total amount of monomers M, of monomers M3 selected from the group consisting of methyl methacrylate, styrene and combinations thereof;

[0152] iv. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, especially 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from the group of monoethylenically unsaturated monomers having an acidic group;

[0153] v. 0% to 9.95% by weight, 0.05% to 9.95% by weight, in particular 0.05% to 5% by weight, especially 0.1% to 4% by weight, based on the total weight of monomers M, of one or more non-ionic monomers M5 having a solubility in deionized water at 20°C and 1 bar of at least 60 g / L,

[0154] wherein the total amount of monomers M1 and M3 is in the range of 5% to 70% by weight, in particular in the range of 10% to 65% by weight, especially in the range of 15% to 60% by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85% by weight, in particular at least 90% by weight, especially at least 95% by weight, based on the total amount of ethylenically unsaturated monomers M.

[0155] In addition to the above monomers M1, M2, M3, M4 and M5, monomers M can comprise one or more further monomers different from the above monomers M. Suitable monomers M different from monomers M1, M2, M3, M4 and M5 include, but are not limited to

[0156] • monomers M6 selected from mono-ethylenically unsaturated non-ionic monomers having a silane functionality or an epoxy group;

[0157] • monomers M7 selected from poly-ethylenically unsaturated monomers, i.e. monomers having at least two non-conjugated ethylenically unsaturated double bonds;

[0158] • monomers M8 selected from mono-ethylenically unsaturated copolymerizable UV initiators.

[0159] Suitable monomers M6 include mono-ethylenically unsaturated silane functional monomers (monomers M6a), such as monomers carrying at least one mono-, di- and / or tri-C1-C4-alkoxysilane group in addition to the ethylenically unsaturated double bond, such as vinyltrimethoxysilane, vinyltriethoxysilane, methacryloyloxy-methyltrimethoxysilane, methacryloyloxy-methyltriethoxysilane, methacryloyloxy-propyltrimethoxysilane, methacryloyloxy-propyltriethoxysilane, methacryloyloxy-ethyltrimethoxysilane, methacryloyloxy-ethyltriethoxysilane, and mixtures thereof. Preferred are methacryloyloxy-propyltrimethoxysilane and vinyltriethoxysilane. The amount of silane functional monomers M6a, if present, will typically not exceed 1% by weight, and is often in the range of 0.01% to 1% by weight, preferably in the range of 0.05% to 0.7% by weight, based on the total amount of ethylenically unsaturated monomers M.

[0160] Suitable monomers M6 also include monoethylenically unsaturated monomers with at least one epoxy group (monomers M6b), in particular glycidyl, such as glycidyl acrylate, glycidyl methacrylate, 2-glycidyloxyethyl acrylate and 2-glycidyloxyethyl methacrylate. If present, the amount of monomers M6b will generally not exceed 2% by weight, and frequently will be in the range of 0.01 to 2% by weight, preferably in the range of 0.05 to 1% by weight, based on the total amount of ethylenically unsaturated monomers M.

[0161] Monomers M can also contain polyethylenically unsaturated monomers (monomers M7), i.e. monomers with at least two non-conjugated ethylenically unsaturated double bonds. The amount of said monomers M7 will generally not exceed 1% by weight, and frequently will be in the range of 0 to 1% by weight, in particular 0 to 0.5% by weight, based on the total amount of ethylenically unsaturated monomers M.

[0162] Examples of polyethylenically unsaturated monomers M7 include:

[0163] - diesters of monoethylenically unsaturated C3-C6-monocarboxylic acids with saturated aliphatic or cycloaliphatic diols, in particular diesters of acrylic or methacrylic acid, such as diacrylates and dimethacrylates of ethylene glycol (1,2-ethanediol), propylene glycol (1,2-propanediol), 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,6-hexanediol and 1,2-cyclohexanediol;

[0164] - monoesters of monoethylenically unsaturated C3-C6-monocarboxylic acids with monoethylenically unsaturated aliphatic or cycloaliphatic monohydroxy compounds, such as acrylates and methacrylates of vinyl alcohol (ethenol), allyl alcohol (2-propen-1-ol), 2-cyclohexen-1-ol or norbornenyl alcohol, such as allyl acrylate and allyl methacrylate; and

[0165] - divinyl aromatic compounds, such as 1,3-divinylbenzene, 1,4-divinylbenzene.

[0166] The polymeric monoethylenically unsaturated copolymerizable UV initiator M8 causes crosslinking of the polymer chains upon exposure to sunlight. The monomer M8 carries an ethylenically unsaturated double bond, in particular an acrylate or methacrylate group, and a moiety which decomposes by UV radiation, thereby forming free radicals. Such groups are typically benzophenone groups, phenone groups, benzoin groups or carbonate groups attached to the carbon of the benzene ring. Such compounds are disclosed, for example, in EP 346734, EP 377199, DE 4037079, DE 3844444, EP 1213 and US 2015 / 0152297. Examples include, but are not limited to, 4-acryloyloxybenzophenone (= 4-benzoylphenyl acrylate), 4-methacryloyloxybenzophenone (= 4-benzoylphenyl 2-methacrylate), 4-(2-acryloyloxyethoxy)benzophenone (= 2-(4-benzoylphenoxy)ethyl acrylate), 4-(2-methacryloyloxyethoxy)benzophenone (= 2-(4-benzoylphenoxy)ethyl 2-methacrylate), O-(2-(meth)acryloyloxyethyl)-O-(benzoylphenyl) carbonate and O-(2-(meth)acryloyloxyethyl)-O-(acetylphenyl) carbonate. The amount of the monomer M8 will typically not exceed 1 % by weight, and if present, typically ranges from 0.01 to 1 % by weight, in particular from 0.02 to 0.5 % by weight, based on the total amount of ethylenically unsaturated monomers M.

[0167] In particular, the monomers M consist of (Example Group 2):

[0168] i. 10 to 69.95 % by weight, in particular 15 to 64.85 % by weight, preferably 20 to 59.4 % by weight, in particular 15 to 40 % by weight, more specifically 15 to 35 % by weight or 20 to 30 % by weight, based on the total amount of monomers M, of an alpha-methylene-gamma-butyrolactone as monomer M1, wherein at least 90 mol-%, in particular at least 95 mol-%, in particular at least 95 mol-% or 100 mol-% of the carbon atoms of the alpha-methylene-gamma-butyrolactone are of biological origin;

[0169] ii. 30 to 89.95 % by weight, in particular 35 to 84.85 % by weight, in particular 40 to 79.4 % by weight, based on the total amount of monomers M, of isobutyl acrylate as monomer M2, wherein at least the carbon atom of the isobutyl group in the isobutyl acrylate is of biological origin, in particular the biocarbon content of the isobutyl methacrylate is at least 54 mol-%, in particular at least 57 mol-%;

[0170] iii. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, especially 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and combinations thereof;

[0171] iv. 0 to 9.95 % by weight, in particular 0.05 to 5 % by weight, especially 0.1 to 4 % by weight, based on the total weight of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar, which have a functional group selected from the group consisting of a hydroxyalkyl group, a primary carboxamide group, a urea group, a ketone group, and combinations thereof; and

[0172] v. 0 to 1 % by weight, especially 0 to 0.5 % by weight, based on the total weight of monomers M, of one or more monomers M7;

[0173] wherein the total amount of monomers M1 and M2 is at least 85 % by weight, in particular at least 90 % by weight, especially at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M;

[0174] or

[0175] i. 10 to 68.95 % by weight, in particular 15 to 63.35 % by weight, preferably 15 to 57.4 % by weight, especially 15 to 40 % by weight, more specifically 15 to 35 % by weight or 15 to 30 % by weight, based on the total amount of monomers M, of an a-methylene-y-butyrolactone as monomer M1, wherein at least 90 mol-%, in particular at least 95 mol-%, especially at least 95 mol-% or 100 mol-% of the carbon atoms of the a-methylene-y-butyrolactone are of biological origin;

[0176] ii. 30 to 80 % by weight, in particular 35 to 75 % by weight, especially 40 to 75 % by weight, based on the total amount of monomers M, of isobutyl acrylate as monomer M2, wherein at least the carbon atoms of the isobutyl group in the isobutyl acrylate are of biological origin, in particular the bio-carbon content of the isobutyl methacrylate is at least 54 mol-%, in particular at least 57 mol-%;

[0177] iii. 1 to 35 % by weight, in particular 1.5 to 30 % by weight, especially 2 to 25 % by weight, based on the total amount of monomers M, of monomers M3 selected from the group consisting of methyl methacrylate, styrene, and combinations thereof;

[0178] iv. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, especially 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and combinations thereof;

[0179] v. 0 to 9.95 % by weight, in particular 0.05 to 5 % by weight, especially 0.1 to 4 % by weight, based on the total weight of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar, which have a functional group selected from the group consisting of a hydroxyalkyl group, a primary carboxamide group, a urea group, a ketone group, and combinations thereof; and

[0180] vi. 0 to 1 % by weight, especially 0 to 0.5 % by weight, based on the total weight of monomers M, of one or more monomers M7;

[0181] wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, in particular in the range of 10 to 65 % by weight, especially in the range of 15 to 60 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, in particular at least 90 % by weight, especially at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M;

[0182] or

[0183] i. 10 to 68.95 % by weight, in particular 15 to 63.35 % by weight, preferably 15 to 57.4 % by weight, especially 15 to 40 % by weight, more specifically 15 to 35 % by weight or 15 to 30 % by weight, based on the total amount of monomers M, of an a-methylene-y-butyrolactone as monomer M1, wherein at least 90 mol-%, in particular at least 95 mol-%, especially at least 95 mol-% or 100 mol-% of the carbon atoms of the a-methylene-y-butyrolactone are of biological origin;

[0184] ii. 30 to 80 % by weight, in particular 35 to 75 % by weight, especially 40 to 75 % by weight, based on the total amount of monomers M, of monomers M2 which are isobutyl acrylate and at least one acrylic acid C2-C 10 a mixture of alkyl acrylates such as n-butyl acrylate, isopentyl acrylate, 2-methylbutyl acrylate, 2-octyl acrylate and 2-ethylhexyl acrylate, wherein at least the carbon atom of the isobutyl group in the isobutyl acrylate is of biological origin, in particular the bio-carbon content of the isobutyl methacrylate is at least 54 mol-%, in particular at least 57 mol-%;

[0185] iii. 1 to 35 % by weight, in particular 1.5 to 30 % by weight, especially 2 to 25 % by weight, based on the total amount of monomers M, of monomer M3 selected from the group consisting of methyl methacrylate, styrene, and combinations thereof;

[0186] iv. 0.05 to 5 % by weight, in particular 0.1 to 4 % by weight, especially 0.5 to 3 % by weight, based on the total amount of monomers M, of one or more monoethylenically unsaturated monomers M4 selected from the group consisting of monoethylenically unsaturated monomers having acidic groups;

[0187] v. 0 to 9.95 % by weight, in particular 0.05 to 5 % by weight, especially 0.1 to 4 % by weight, based on the total weight of monomers M, of one or more non-ionic monomers M5 having a solubility of at least 60 g / L in deionized water at 20 °C and 1 bar,

[0188] vi. 0 to 1 % by weight, especially 0 to 0.5 % by weight, based on the total weight of monomers M, of one or more monomers M7;

[0189] wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, in particular in the range of 10 to 65 % by weight, especially in the range of 15 to 60 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, in particular at least 90 % by weight, especially at least 95 % by weight, based on the total amount of ethylenically unsaturated monomers M.

[0190] Preferably, the particles of the copolymer contained in the polymer latex have a Z-average particle size in the range of 50 to 500 nm, in particular in the range of 60 to 350 nm, as determined by quasi-elastic light scattering (QELS). The particle size distribution of the copolymer particles contained in the polymer latex can be unimodal or almost unimodal, which means that the distribution function of the particle sizes has a single maximum and no specific shoulder. The particle size distribution of the copolymer particles contained in the polymer latex can also be multimodal or almost multimodal, which means that the distribution function of the particle sizes has at least two different maxima or at least one maximum and at least one distinct shoulder.

[0191] The size of the particles and the particle size distribution is determined by quasi-elastic light scattering (QELS), also known as dynamic light scattering (DLS), if not stated otherwise. The measurement method is described in the ISO 13321 :1996 standard. The determination can be performed using a high performance particle sizer (HPPS). For this purpose, a sample of the dilute aqueous polymer latex is taken and the analysis dilution is prepared. In the context of QELS, the aqueous dilution can have a polymer concentration in the range of 0.001 to 0.5% by weight, depending on the particle size. For most purposes, a suitable concentration will be 0.01% by weight. However, higher or lower concentrations can be used to achieve the best signal-to-noise ratio. The dilution can be achieved by adding the polymer latex to water or an aqueous solution of a surfactant to avoid flocculation. Typically, the dilution is performed by using a 0.1% by weight aqueous solution of a non-ionic emulsifier, such as an ethoxylated Ci6 / Ci8-alkanol (degree of ethoxylation 18), as diluent. Measurement configuration: HPPS from Malvern, automated, with continuous flow cuvette and Gilson autosampler. Parameters: measurement temperature 20.0 °C; measurement time 120 seconds (6 cycles, each cycle 20 s); scattering angle 173°; wavelength laser 633 nm (HeNe); refractive index of the medium 1.332 (aqueous); viscosity 0.9546 mPa-s. The measurement gives the average value of the second order cumulants analysis, the so-called z-average. The "z-average" is the intensity-weighted average hydrodynamic particle diameter in nm.

[0192] The hydrodynamic particle diameter can also be determined by hydrodynamic chromatography fractionation (HDC), as described, for example, by H. Wiese in "Characterization of Aqueous Polymer Dispersions" in Polymer Dispersions and Their Industrial Applications (Wiley-VCH Verlag, 2002), pages 41-73. For further details, reference is made to the examples and description below.

[0193] The copolymer contained in the polymer particles can form a single phase, or it can form different phases if the polymer particles contain different copolymers which differ in their monomer composition. Preferably, the polymer particles contained in the aqueous polymer latex according to the application comprise a polymer phase having a glass transition temperature Tg of not more than 50 °C, in particular at most 40 °C, preferably in the range of -25 °C to + 50 °C, in particular in the range of -20 °C to + 40 °C.

[0194] The glass transition temperature as referred to herein is the real glass transition temperature. The real glass transition temperature can be experimentally determined by the differential scanning calorimetry (DSC) method according to ISO 11357-2:2013, preferably with sample preparation according to ISO 16805:2003.

[0195] The real glass transition temperature depends on the monomer composition forming the polymer and thus the theoretical glass transition temperature can be calculated from the monomer composition used in the emulsion polymerization. The theoretical glass transition temperature is usually calculated from the monomer composition by the Fox equation:

[0196] 1 / Tg t = x a / Tg a + x b / Tg b +.... x n / Tg n ,

[0197] In this equation, x a , x b ,.... x n are the mass fractions of the monomers a, b,.... n and Tg a , Tg b ,.... Tg nis the actual glass transition temperature (in Kelvin) of a homopolymer synthesized only once from one of the monomers 1, 2,... n. The Fox equation is described by T. G. Fox in Bull. Am. Phys. Soc. 1956, 1, p. 123 and in Ullmann's Encyclopädie der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], Vol. 19, p. 18, 4thEdition, Verlag Chemie, Weinheim, 1980. The actual Tg values of homopolymers of most monomers are known and listed e.g. in Ullmann's Encyclopädie der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 5thEdition, Vol. A21, p. 169, Verlag Chemie, Weinheim, 1992. Additional sources for glass transition temperatures of homopolymers are e.g. J. Brandrup, E. H. Immergut, Polymer Handbook, 1stEdition, J. Wiley, New York 1966, 2ndEdition J. Wiley, New York 1975, 3rdEdition J. Wiley, New York 1989 and 4thEdition J. Wiley, New York 2004.

[0198] Generally, the theoretical glass temperature Tg calculated according to Fox as described herein t and the experimentally determined glass transition temperature as described herein are similar or even identical and deviate from each other by not more than 5 K, in particular they deviate by not more than 2 K. Thus, both the actual glass transition temperature and the theoretical glass transition temperature of the polymer phases (1) and (2) can be adjusted by selecting appropriate monomers Ma, Mb... Mn and their mass fractions x a , x b ,... x n in the monomer composition in order to achieve the desired glass transition temperatures Tg(1) and Tg(2), respectively. It is common knowledge for the skilled person to select appropriate amounts of monomers Ma, Mb... Mn for obtaining copolymers and / or copolymer phases with desired glass transition temperatures.

[0199] Preferably, the aqueous polymer latex of the present application has a pH of at least pH 3, for example in the range of pH 3 to pH 11.5.

[0200] The aqueous polymer dispersion of the present application typically has a solids content in the range of 30% to 75% by weight, in particular in the range of 40% to 65% by weight, preferably in the range of 45% to 60% by weight. The solids content describes the proportion of the non-volatile fraction. The solids content of the dispersion is determined by means of a balance with infrared moisture analysis. In this determination, an amount of the polymer dispersion is introduced into the instrument, heated to 140°C and subsequently held at this temperature. The measurement procedure is ended as soon as the average reduction in weight falls below 1 mg within 140 seconds. The ratio of the weight after drying to the original mass introduced gives the solids content of the polymer dispersion. The total solids content of the formulation is determined arithmetically from the amount of the substances added and their solids content and concentration.

[0201] If the polymer in the polymer latex has functional groups complementary to the functional groups of the crosslinking agent, the polymer dispersion can contain a crosslinking agent for achieving postcrosslinking of the polymer latex particles. In this context, the term "complementary" is to be understood in the sense that the functional groups of the latex and the functional groups of the crosslinking agent are susceptible to a chemical reaction which forms a chemical bond between the atoms of the respective functional groups. Typically, the crosslinking agent has at least two functional groups complementary to the functional groups of the polymer of the polymer latex. Examples of suitable crosslinking agents are described below.

[0202] In addition to the polymer and optionally the crosslinking agent, the aqueous polymer dispersion of the present application can also contain further ingredients which are conventionally present in aqueous polymer dispersions. These further ingredients are, for example, surface-active compounds, such as emulsifiers and protective colloids, in particular those used for producing the polymer latex, further antifoams, etc. The further ingredients can also be acids, bases, buffers, decomposition products from the polymerization reaction, odor-reducing compounds and chain transfer agents. Furthermore, the polymer latex can contain biocides for avoiding microbial spoilage. The amount of the respective individual components will typically not exceed 1.5 wt% based on the total weight of the polymer dispersion. The total amount of these stated components will typically not exceed 5 wt% based on the total weight of the polymer latex.

[0203] Preferably, the amount of volatile organic substances, i.e. the content of organic compounds having a boiling point of up to 250°C at standard conditions (101,325 kPa) as determined by ISO 17895:2005 via gas chromatography, is less than 0.5% by weight, in particular less than 0.2% by weight, based on the total weight of the polymer latex.

[0204] In addition to the polymer, the aqueous polymer latex also contains an aqueous phase in which the polymer particles of the polymer latex are dispersed. The aqueous phase (also referred to as the serum) essentially consists of water and any water-soluble additional ingredients. The total concentration of any additional ingredients will typically not exceed 10 wt%, in particular 8% by weight, based on the total weight of the aqueous phase.

[0205] The aqueous polymer latex of the present application can be prepared by any method for preparing an aqueous dispersion of a polymer made from the polymerizing monomers M. In particular, the aqueous polymer latex of the present application is prepared by aqueous emulsion polymerization, in particular by free-radical aqueous emulsion polymerization of the monomers M. The term "free-radical aqueous emulsion polymerization" means that the polymerization of the monomers M is initiated by free radicals formed by decay of a polymerization initiator, whereby free radicals are formed in the polymerization mixture. It is therefore also referred to as "radically initiated emulsion polymerization". Procedures for the radically initiated emulsion polymerization of monomers in aqueous media have been widely described and are therefore sufficiently familiar to the skilled person [in this respect see "Emulsion Polymerization" in Encyclopedia of Polymer Science and Engineering, Vol. 8, p. 659 ff (1987); D.C. Blackley, in High Polymer Latices, Vol. 1, p. 35 ff (1966); H. Warson, The Applications of Synthetic Resin Emulsions, Chapter 5, p. 246 ff (1972); D. Diederich, Chemie in unserer Zeit 24, p. 135-142 (1990); Emulsion Polymerisation, Interscience Publishers, New York (1965); DE-A 40 03 422; and Dispersionen synthetischer Hochpolymerer, F. Holscher, Springer-Verlag, Berlin (1969)]. Typical procedures for the aqueous emulsion polymerization of ethylenically unsaturated monomers are also described in the patent literature discussed in the introductory part of the present patent application.

[0206] The radical-initiated aqueous emulsion polymerization is typically carried out by emulsifying the ethylenically unsaturated monomers in an aqueous medium forming an aqueous phase, typically by using surface-active compounds such as emulsifiers and / or protective colloids, and polymerizing the system using at least one initiator which decays by forming radicals and thereby initiates the chain growth addition polymerization of the ethylenically unsaturated monomers M. The preparation of the aqueous polymer dispersion according to the present application can differ from this general procedure only in the specific use of the above mentioned monomers M1 to M8. It will be understood here that for the purpose of the present specification the method shall also encompass seed, staged, one-shot and gradient protocols which are familiar to the skilled person.

[0207] The radical-initiated aqueous emulsion polymerization is triggered by a radical polymerization initiator (radical initiator). These can in principle be peroxides or azo compounds. Of course, redox initiator systems are also usable. In principle, the peroxides used can be inorganic peroxides such as hydrogen peroxide, or peroxodisulfates such as the mono- or di-alkali metal or ammonium salts of peroxodisulfuric acid, for example the mono- and disodium salts, the potassium salt or the ammonium salt, or organic peroxides such as alkyl hydroperoxides, for example tert-butyl hydroperoxide, p-menthyl hydroperoxide or cumyl hydroperoxide and also 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 from Wako Chemicals). Suitable oxidizing agents for the redox initiator systems are essentially the above specified peroxides. Corresponding reducing agents which can be used are sulfur compounds having a low oxidation state, such as alkali metal sulfites, for example potassium and / or sodium sulfite; alkali metal bisulfites, for example potassium and / or sodium bisulfite; alkali metal pyrosulfites, for example potassium and / or sodium pyrosulfite; formaldehyde sulfoxylates, for example potassium and / or sodium formaldehyde sulfoxylate; alkali metal salts, especially potassium and / or sodium salts, of aliphatic sulfmic acids; and alkali metal hydrosulfides, for example potassium and / or sodium hydrosulfide; salts of polyvalent metals, such as iron(II) sulfate, iron(II) ammonium sulfate, iron(II) phosphate; enediols, such as dihydroxymaleic acid, benzoin and / or ascorbic acid; and reducing sugars, such as sorbitol, glucose, fructose and / or dihydroxyacetone.

[0208] Preferred radical initiators are inorganic peroxides, especially peroxodisulfates.

[0209] In general, the amount of the radical initiator used is 0.05 to 2 pphm based on the total amount of monomers M, preferably 0.1 to 1 pphm based on the total amount of monomers M.

[0210] The amount of free-radical initiator required for the emulsion polymerization of monomers M can be initially fully charged to the polymerization vessel. However, it is also possible to charge no 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 to add any remaining amount of free-radical initiator to the free-radical polymerization under the polymerization conditions. Preferably, at least 70%, in particular at least 80%, especially at least 90% or the total amount of polymerization initiator is fed to the free-radical polymerization under the polymerization conditions. The feed of monomers M can be carried out in one or more portions batchwise or continuously at a constant or varying flow rate according to the consumption during the free-radical emulsion polymerization of monomers M.

[0211] Generally, the term "polymerization conditions" is to be understood to mean those temperatures and pressures under which the free-radically initiated aqueous emulsion polymerization takes place 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 chosen such that there is always a sufficient amount of initiating radicals to initiate or maintain the polymerization reaction.

[0212] Preferably, the free-radical emulsion polymerization of monomers M is carried out by means of the so-called feed method (also referred to as 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 under the polymerization conditions during a metering period P. The addition can be carried out batchwise and preferably continuously at a constant or varying feed rate. The duration of the period P can depend on the production equipment and can vary from, for example, 20 minutes to 12 h. Frequently, the duration of the period P will be in the range from 0.5 h to 8 h, in particular from 1 h to 6 h. In a multi-step emulsion polymerization step, the total duration of all steps is typically in the above range. The duration of the individual steps is typically shorter. Preferably, at least 70%, in particular at least 80%, especially at least 90% or the total amount of polymerization initiator is introduced into the emulsion polymerization simultaneously with the addition of monomers.

[0213] The aqueous free-radical emulsion polymerization is generally carried out in the presence of one or more suitable surfactants. These surfactants typically comprise emulsifiers and provide micelles in which the polymerization takes place, and these micelles serve to stabilize the monomer droplets during the aqueous emulsion polymerization and also to grow the polymer particles. The surfactants used in the emulsion polymerization are generally not separated from the polymer dispersion, but remain in the aqueous polymer dispersion obtainable by the emulsion polymerization of monomers M.

[0214] The surface active agents can be selected from emulsifiers and protective colloids. In contrast to emulsifiers, protective colloids are understood as meaning polymeric compounds having a molecular weight above 2000 Dalton, whereas emulsifiers typically have a lower molecular weight. The surface active agents can be anionic or non-ionic surface active agents or a mixture of non-ionic and anionic surface active agents.

[0215] Anionic surface active agents typically carry at least one anionic group, which is typically selected from the group consisting of phosphate, phosphonate, sulfate and sulfonate groups. Anionic surface active agents carrying at least one anionic group are typically used in the form of their alkali metal salts, in particular their sodium salts, or in the form of their ammonium salts.

[0216] Preferred anionic surface active agents are anionic emulsifiers, in particular those carrying at least one sulfate or sulfonate group. Likewise, anionic emulsifiers carrying at least one phosphate or phosphonate group can be used as the sole anionic emulsifier or in combination with one or more anionic emulsifiers carrying at least one sulfate or sulfonate group.

[0217] Examples of anionic emulsifiers carrying at least one sulfate or sulfonate group are, for example,

[0218] - alkyl sulfates, in particular C8-Ci8alkyl sulfates, 22 - salts, in particular alkali metal salts and ammonium salts, of alkyl esters,

[0219] - sulfuric monoesters of ethoxylated alkanols, in particular ethoxylated C8-Ci8alkanols, 22 - salts, in particular alkali metal salts and ammonium salts, of sulfuric monoesters of alkanols, preferably having an ethoxylation level (EO level) in the range from 2 to 40,

[0220] - alkyl sulfonic acids, in particular C8-Ci8alkyl sulfonic acids, 22 - salts, in particular alkali metal salts and ammonium salts, of alkyl sulfonic acids,

[0221] - dialkyl esters of sulfosuccinic acid, in particular di-C4-Ci8alkyl esters of sulfosuccinic acid, 18 - salts, in particular alkali metal salts and ammonium salts, of alkyl esters,

[0222] - alkylbenzenesulfonic acids, in particular C4-Ci8alkylbenzenesulfonic acids, 22 - salts, in particular alkali metal salts and ammonium salts, of alkylbenzenesulfonic acids, and

[0223] - mono- or di-sulfonated alkyl-substituted diphenyl ethers, for example carrying C4-Ci8alkyl groups on one or both aromatic rings, 24- salts, especially alkali metal salts and ammonium salts, of bis(phenylsulfonic acid) ethers of alkyls. The latter are common general knowledge, for example from US-A-4,269,749, and are commercially available, for example as Dowfax® 2A1 (Dow Chemical Company),

[0224] - surfactants having a polymerizable ethylenically unsaturated double bond as described herein, for example compounds of the formulae (I) - (IV), wherein X and Y are SO3 - or O-SO3 - .

[0225] Examples of anionic emulsifiers with phosphate or phosphonate groups include, but are not limited to, the following salts selected from the following group:

[0226] - mono- and dialkylphosphates, especially C8-C 22 - salts, especially alkali metal salts and ammonium salts, of alkylphosphates,

[0227] - phosphoric monoesters of C2-C3-alkoxylated alkanols, preferably having an alkoxylation level in the range from 2 to 40, especially in the range from 3 to 30, for example ethoxylated C8-C 22 - phosphoric monoesters of C8-C 22 - phosphoric monoesters of C8-C 22 - salts, especially alkali metal salts and ammonium salts, of phosphoric monoesters of alkanols, preferably having an ethoxylation level (EO level) in the range from 1 to 20 and a propoxylation level in the range from 1 to 20,

[0228] - alkylphosphonic acids, especially C8-C 22 - salts, especially alkali metal salts and ammonium salts, of alkylphosphonic acids, and

[0229] - alkylbenzenephosphonic acids, especially C4-C 22 - salts, especially alkali metal salts and ammonium salts, of alkylbenzenephosphonic acids.

[0230] - surfactants having a polymerizable ethylenically unsaturated double bond as described herein, for example compounds of the formulae (I) - (IV), wherein X and Y are HPO3 - , PO3 2 , O-HPO3 - or O-PO3 2 .

[0231] The anionic emulsifiers can also comprise emulsifiers having a polymerizable double bond, such as the emulsifiers having the formulae (I) to (IV) and salts thereof, in particular alkali metal or ammonium salts thereof:

[0232]

[0233] In formula (I), R 1 is H, CrC 20 -alkyl, C5-C 10 -cycloalkyl, phenyl optionally substituted with CrC 20 -alkyl, R 2 and R 2’ are each H or together are O, R 3 and R 4 are H or methyl, m is 0 or 1, n is an integer from 1 to 100, and X is SO3 - , O-SO3 - , O-HPO3 - or O-PO3 2- .

[0234] (II)

[0235] In formula (II), R is H, CrC 20 -alkyl, C5-C 10 -cycloalkyl, phenyl optionally substituted with CrC 20 -alkyl, k is 0 or 1, and X is SO3 - , O-SO3 - , O-HPO3 - or O-PO3 2- .

[0236] (III)

[0237] In formula (III), R 1 is H, CrC 20 -alkyl, O-CrC 20 -alkyl, C5-C 10 -cycloalkyl, O-C5-C 10 -cycloalkyl, O-phenyl optionally substituted with CrC 20 -alkyl, n is an integer from 1 to 100, and Y is SO3 - , HPO3 - or PO3 2- .

[0238] (IV)

[0239] In formula (IV), R 1 is H, C1-C 20 -alkyl or 1-phenylethyl, R 2 is H, C1-C 20 -alkyl or 1-phenylethyl, A is C2-C4-alkanediyl, such as 1,2-ethanediyl, 1,2-propanediyl, 1,2-butanediyl or 1,4-butanediyl, n is an integer from 1 - 100, and Y is SO3 - , HPO3 - or PO3 2- .

[0240] Specific embodiments of the co-copolymerizable emulsifiers of formula (I) are also known as polyethylene glycol monoacrylate sulfates or phosphates. Specific embodiments of the co-copolymerizable emulsifiers of formula (I) can also be known as polyethylene glycol monoacrylate phosphonates, or allyl ether sulfates. Commercially available co-copolymerizable emulsifiers of formula (I) are Maxemul® emulsifiers, Sipomer® PAM emulsifiers, Latemul® PD, and ADEKA Reasoap® PP-70.

[0241] Specific embodiments of the co-copolymerizable emulsifiers of formula (II) are also known as alkyl allyl sulfosuccinates. Commercially available co-copolymerizable emulsifiers of formula (II) are Trem® LF40.

[0242] Specific embodiments of the co-copolymerizable emulsifiers of formula (III) are also known as branched unsaturated. Commercially available co-copolymerizable emulsifiers of formula (III) are Adeka® Reasoap emulsifiers and Hitenol® KH.

[0243] Specific embodiments of the co-copolymerizable emulsifiers of formula (IV) are also known as polyoxyethylene alkyl phenyl ether sulfates and polyoxyethylene mono or di styryl phenyl ether sulfates. Commercially available co-copolymerizable emulsifiers of formula (IV) are Hitenol® BC and Hitenol® AR emulsifiers.

[0244] Other suitable anionic surfactants can be found in Houben-Weyl, Methoden derorganischen Chemie [Methods of Organic Chemistry], Vol. XIV / 1, Makromolekulare Stoffe [Macromolecular Substances], Georg-Thieme-Verlag, Stuttgart, 1961, pp. 192-208.

[0245] Preferably, the surfactant comprises at least one anionic emulsifier having at least one sulfate or sulfonate group. At least one anionic emulsifier having at least one sulfate or sulfonate group may be the only type of anionic emulsifier. However, a mixture of at least one anionic emulsifier having at least one sulfate or sulfonate group and at least one anionic emulsifier having at least one phosphate or phosphonate group may also be used. In such mixtures, the amount of at least one anionic emulsifier having at least one sulfate or sulfonate group is preferably at least 50% by weight, based on the total weight of the anionic surfactants used in the method of the present invention. In particular, the amount of anionic emulsifier having at least one phosphate or phosphonate group does not exceed 20% by weight, based on the total weight of the anionic surfactants used in the method of the present invention.

[0246] Preferred anionic surfactants are anionic emulsifiers selected from the group consisting of, or mixtures thereof:

[0247] -Alkyl sulfates, especially C8-C sulfates 22 Salts of alkyl esters, especially alkali metal salts and ammonium salts.

[0248] - Sulfated monoesters of ethoxylated alkanols, especially ethoxylated C8-C 22 Salts of sulfate monoesters of alkyl alcohols (preferably having an ethoxylation level (EO level) in the range of 2 to 40), especially alkali metal salts,

[0249] -Ethoxylated alkylphenol sulfate monoesters, especially ethoxylated C4-C 18 alkylphenol sulfate monoesters (preferably with an EO level of 3 to 40),

[0250] -alkylbenzene sulfonic acids, especially C4-C 22 -alkylbenzene sulfonic acid, and

[0251] - Mono- or disulfonated alkyl-substituted diphenyl ethers, for example, having a C4-C4 bond on one or both aromatic rings. 24-alkyl bis(benzenesulfonic acid) ethers.

[0252] - Polymerizable emulsifiers of formula (III).

[0253] Particularly preferred are anionic emulsifiers, which are selected from the group consisting of, and mixtures thereof:

[0254] -Alkyl sulfates, especially C8-C sulfates 22 Salts of alkyl esters, especially alkali metal salts and ammonium salts.

[0255] - Sulfated monoesters of ethoxylated alkanols, especially ethoxylated C8-C 22 Salts of sulfate monoesters of alkyl alcohols (preferably having an ethoxylation level (EO level) in the range of 2 to 40), especially alkali metal salts,

[0256] - Mono- or disulfonated alkyl-substituted diphenyl ethers, for example, having a C4-C4 bond on one or both aromatic rings. 24 -alkyl bis(benzenesulfonic acid) ether

[0257] - A polymerizable emulsifier having formula (III), wherein Y is SO3 - .

[0258] In addition to the anionic surfactants mentioned above, surfactants may also contain one or more nonionic surfactants, particularly selected from nonionic emulsifiers. Suitable nonionic emulsifiers are, for example, aryl or aliphatic nonionic emulsifiers, such as ethoxylated mono, di, and trialkylphenols (EO level: 3 to 50, alkyl: C4-C). 10 ), ethoxylated long-chain alcohols (EO level: 3 to 100, alkyl: C8-C) 36 ) and poly(ethylene oxide) / poly(propylene oxide) homopolymers and copolymers. These may contain ethylene oxide units copolymerized in a random distribution or in a block form. A very suitable example is an EO / PO block copolymer. Preferred are ethoxylated long-chain alkanols, particularly alkyl C8-C alkyl groups having an average ethoxylation level of 5 to 100. 30 Those, and among these, those with linear C are particularly preferred. 12 -C 20 Alkyl groups and those with average ethoxylation levels of 10 to 50, as well as ethoxylated monoalkylphenols.

[0259] The surfactant used in the process of the present application will typically comprise no more than 30% by weight, in particular no more than 20% by weight, of non-ionic surfactant, based on the total amount of surfactant used in the process of the present application, and in particular will comprise no non-ionic surfactant at all. It is also possible to use a combination of at least one anionic surfactant and at least non-ionic surfactant. In this case, the weight ratio of the total amount of anionic surfactant to the total amount of non-ionic surfactant is in the range of 99 : 1 to 70 : 30, in particular in the range of 98 : 2 to 75 : 25, especially in the range of 95 : 5 to 80 : 20.

[0260] Preferably, the surfactant will be used in such an amount that the amount of surfactant is in the range of 0.2% to 5% by weight, in particular in the range of 0.3% to 4.5% by weight, based on the monomers M to be polymerized. In a multi-step emulsion step emulsion polymerization, the surfactant will be used in such an amount that the amount of surfactant is typically in the range of 0.2% to 5% by weight, in particular in the range of 0.3% to 4.5% by weight, based on the total amount of monomers polymerized in the respective step.

[0261] Preferably, the major part, i.e. at least 80%, of the surfactant used is added to the emulsion polymerization while the monomers are added. In particular, the monomers are added to the polymerization reaction as an aqueous emulsion which contains at least 80% of the surfactant used in the emulsion polymerization.

[0262] It has been found advantageous to conduct the radical emulsion polymerization of the monomers M in the presence of a seed latex. A seed latex is a polymer latex which is present in the aqueous polymerization medium prior to the start of the polymerization of the monomers M. The seed latex can help to better adjust the particle size of the final polymer latex obtained in the radical emulsion polymerization of the present application.

[0263] In principle, every polymer latex can be used as seed latex. For the purpose of the present application, seed latexes are preferred in which the particle size of the polymer particles is relatively small. In particular, the Z-average particle diameter of the polymer particles of the seed latex (as determined at 20°C by dynamic light scattering (DLS) (see below)) is preferably in the range of 10 to 80 nm, in particular 10 to 50 nm. Preferably, the polymer particles of the seed latex are formed from ethylenically unsaturated monomers which comprise at least 95% by weight, based on the total weight of the monomers forming the seed latex, of one or more monomers selected from the group consisting of acrylic acid, C2-C 10- alkyl esters, in particular ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethyl-hexyl acrylate; C1-C4-alkyl methacrylates such as methyl methacrylate; mono-olefinically unsaturated nitriles such as acrylonitrile; and vinyl aromatic monomers as defined above, such as styrene; and mixtures thereof. In particular, the polymer particles of the seed latex are made from olefinically unsaturated monomers comprising at least 95 % by weight, based on the total weight of the monomers forming the seed latex, of one or more monomers selected from the group consisting of C1-C4-alkyl methacrylates such as methyl methacrylate, mono-olefinically unsaturated nitriles such as acrylonitrile and vinyl aromatic monomers as defined above, such as styrene, and mixtures thereof.

[0264] To this end, the seed latex is typically charged into the polymerization vessel prior to the start of the polymerization of the monomers M. In particular, the seed latex is charged into the polymerization vessel, followed by establishing the polymerization conditions, for example by heating the mixture to the polymerization temperature. It can be beneficial to charge at least a portion of the free-radical initiator into the polymerization vessel prior to the start of the addition of the monomers M. However, it is also possible to add the monomers M and the free-radical polymerization initiator concurrently to the polymerization vessel.

[0265] The amount of the seed latex as a solid calculation can often be in the range of 0.01 to 10 % by weight, preferably in the range of 0.05 to 5 % by weight, in particular in the range of 0.05 to 3 % by weight, based on the total weight of the monomers in the monomer composition M to be polymerized.

[0266] The free-radical aqueous emulsion polymerization of the present application can be carried out at a temperature in the range of 0 °C to 170 °C. The temperature employed is typically in the range of 50 °C to 120 °C, often 60 °C to 120 °C and often 70 °C to 110 °C. The free-radical aqueous emulsion polymerization of the present application can be carried out at a pressure of less than, equal to or greater than 1 atm (atmospheric pressure), and thus the polymerization temperature can exceed 100 °C and can be as high as 170 °C. The polymerization of the monomers is typically carried out at ambient pressure, but it 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 pressure) or even higher. If the emulsion polymerization is carried out under reduced pressure, a pressure of 950 mbar, often 900 mbar and often 850 mbar (absolute pressure) is established. Advantageously, the free-radical aqueous emulsion polymerization of the present application is carried out at ambient pressure (about 1 atm) under exclusion of oxygen, for example under an inert gas atmosphere, for example under nitrogen or argon.

[0267] The process for producing the polymer latex of the present application can be a single stage polymerization or a multi-stage emulsion polymerization. In a single stage polymerization, the overall composition of monomers M fed to the polymerization reaction under polymerization conditions remains the same or nearly the same, while in a multi-stage emulsion polymerization, the overall composition of monomers M fed to the polymerization reaction under polymerization conditions is changed at least once, in particular such that the theoretical glass transition temperature of the resulting polymer formed in one stage differs from the theoretical glass transition temperature of the resulting polymer formed in another stage by at least 10 °C, in particular by at least 20 °C or at least 40 °C.

[0268] In a particular embodiment group, the process of the present application is carried out as a 2-stage emulsion polymerization, i.e. the composition of monomers fed to the polymerization reaction under polymerization conditions is modified once, or as a 3-stage or 4-stage emulsion polymerization, i.e. the composition of monomers fed to the polymerization reaction under polymerization conditions is modified twice or three times.

[0269] The polymerization of the monomers M can optionally be carried out in the presence of a chain transfer agent. Chain transfer agent is understood to mean a compound which transfers a free radical and reduces the molecular weight of the growing chain and / or controls the chain growth in the polymerization. Examples of chain transfer agents are aliphatic and / or araliphatic halogen compounds, such as n-butyl chloride, n-butyl bromide, n-butyl iodide, dichloromethane, dichloroethane, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, carbon tetrabromide, benzyl chloride, benzyl bromide, organic thio compounds, such as primary, secondary or tertiary aliphatic mercaptans, for example ethanethiol, n-propanethiol, 2-propanethiol, n-butane- thiol, 2-butane-thiol, 2-methyl-2-propanethiol, n-pentanethiol, 2-pentanethiol, 3- pentanethiol, 2-methyl-2-butane-thiol, 3-methyl-2-butane-thiol, n-hexanethiol, 2- hexanethiol, 3-hexanethiol, 2-methyl-2-pentanethiol, 3-methyl-2-pentanethiol, 4- methyl-2-pentanethiol, 2-methyl-3-pentanethiol, 3-methyl-3-pentanethiol, 2- ethylbutanethiol, 2-ethyl-2-butane-thiol, n-heptanethiol and its isomeric compounds, n-octanethiol and its isomeric compounds, n-nonanethiol and its isomeric compounds, n-decanethiol and its isomeric compounds, n-undecanethiol and its isomeric compounds, n-dodecanethiol and its isomeric compounds, n-tridecanethiol and its isomeric compounds, substituted mercaptans, for example 2-hydroxyethanethiol, aromatic mercaptans, such as benzene- thiol, o-, m- or p-methylbenzene-thiol, alkyl esters of mercaptoacetic acid (thiolactic acid), such as 2-ethylhexyl thioglycolate, alkyl esters of mercaptopropionic acid, such as octyl mercaptopropionate, and also further sulfur compounds described in Polymer Handbook, 3rd edition, 1989, J. Brandrup and E. H. Immergut, John Wiley & Sons, section II, pages 133 to 141, and also aliphatic and / or aromatic aldehydes, such as acetaldehyde, propionaldehyde and / or benzaldehyde, unsaturated fatty acids, such as oleic acid, dienes having non-conjugated double bonds, such as divinylmethane or vinylcyclohexane, or hydrocarbons having hydrogen atoms which are easily abstracted, for example toluene.

[0270] Alternatively, mixtures of the above-mentioned chain transfer agents which do not interfere with one another can be used. The total amount of chain transfer agent which is optionally used in the process according to the application will generally not exceed 2% by weight, in particular 1% by weight, based on the total amount of monomers M. It is possible, however, that the amount of chain transfer agent added to the polymerization reaction during a certain period of the polymerization reaction can exceed the value of 2% by weight, based on the total amount of monomers M added to the polymerization reaction during said period, and can be up to 8% by weight, in particular at most 4% by weight.

[0271] When the aqueous polymer dispersion obtained upon completion of the polymerization of the monomers M is subjected to a post-treatment to reduce the residual monomer content, it is often advantageous. This post-treatment is carried out chemically, for example by using a more effective radical initiator system to complete the polymerization (so-called post-polymerization), 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 771328, DE-A 19624299, DE-A 19621027, DE-A 19741184, DE-A 19741187, DE-A 19805122, DE-A 19828183, DE-A 19839199, DE-A 19840586 and DE-A 19847115. The combination of chemical and physical post-treatment has the advantage that it not only removes unconverted ethylenically unsaturated monomers from the aqueous polymer dispersion, but also other damaging volatile organic constituents (VOCs).

[0272] Since the polymers contained in the aqueous polymer dispersion can contain acidic groups from the monomers M4 and optionally from the polymerization initiator, the aqueous polymer dispersion obtained by the process of the application is often neutralized before it is formulated into a coating composition. The neutralization of the acidic groups of the polymer is effected after the polymerization and / or during the polymerization by means of neutralizing agents known to the person skilled in the art. For example, the neutralizing agent can be added in the joint feed with the monomers to be polymerized or in a separate feed. Suitable neutralizing agents include organic amines, alkali metal hydroxides, ammonium hydroxides. In particular, the neutralization is effected by using ammonia or an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide.

[0273] In addition, it can be suitable to formulate the polymer latex of the application with a post-curing agent. Ideally, such a post-curing agent (also called post-crosslinking agent) will induce a crosslinking reaction during and / or after film formation by forming coordinate or covalent bonds with reactive sites on the surface of the polymer particles.

[0274] Crosslinking agents suitable for providing post-crosslinking are, for example, compounds having at least two functional groups selected from oxazoline, amino, aldehyde, aminooxy, carbodiimide, aziridinyl, epoxy and hydrazide groups, derivatives or compounds with acetoacetyl groups. These crosslinking agents react with the reactive sites of the polymer of the polymer dispersion which bear complementary functional groups capable of forming covalent bonds with the crosslinking agent. Suitable systems are known to the skilled person.

[0275] Since the polymer contained in the polymer dispersion of the present application carries carboxyl groups, the post-crosslinking can be achieved by formulating the polymer dispersion with one or more polycarbodiimides as described in US 4977219, US 5047588, US 5117059, EP 0277361, EP 0507407, EP 0628582, US 5352400, US 2011 / 0151128 and US 2011 / 0217471. The crosslinking is assumed to be based on the reaction of the carboxyl groups of the polymer with the polycarbodiimide. The reaction typically leads to covalent crosslinking based mainly on N-acylurea bonds (J.W. Taylor and D.R. Bassett, in E.J. Glass (ed.), Technology for Waterborne Coatings, ACS Symposium Series 663, Am. Chem. Soc., Washington, D.C., 1997, Chapter 8, pages 137 to 163).

[0276] Likewise, since the polymer particles contained in the polymer dispersion of the present application carry carboxyl groups derived from monomer M4, a suitable post-curing agent can also be a water-soluble or water-dispersible polymer carrying oxazoline groups, for example a polymer as described in US 5300602 and WO 2015 / 197662.

[0277] The post-crosslinking can also be achieved by analogy to EP 1227116, which describes an aqueous two-component coating composition containing a binder polymer having carboxylic acid and hydroxyl functional groups and a multifunctional crosslinker having functional groups selected from isocyanate, carbodiimide, aziridinyl and epoxy groups.

[0278] If the polymer in the polymer dispersion carries ketone groups, for example by using monomer M5c such as diacetone acrylamide (DAAM), the post-crosslinking can be achieved by formulating the aqueous polymer dispersion with one or more dihydrazides, in particular aliphatic dicarboxylic acids such as adipic acid dihydrazide (ADDH), as described in US 4931494, US 2006 / 247367 and US 2004 / 143058. These components react essentially during and after film formation, although some degree of preliminary reaction can occur.

[0279] Other suitable agents for achieving post-curing include

[0280] - epoxy silanes for crosslinking carboxyl groups in the polymer;

[0281] - dialdehydes for crosslinking urea groups or acetoacetoxy groups such as glyoxal, such as those derived from monomers M5b and M5c, respectively, as defined herein, in particular urea (meth)acrylate or acetoacetoxyethyl (meth)acrylate;

[0282] - diamines and / or polyamines for crosslinking keto groups or epoxy groups, such as those derived from monomers M5c or M6b as defined herein; and

[0283] - UV initiators such as benzophenones including benzophenone, 4-methoxybenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, acetophenones such as 2-hydroxy-2,2-dimethylacetophenone, 2-phenyl-2,2-dimethylacetophenone, cycloalkyl phenyl ketones such as 1-benzoylcyclohexan-1-ol (= 1-hydroxycyclohexyl phenyl ketone) and benzoin and mixtures thereof, in particular liquid mixtures such as mixtures of 4-methylbenzophenone and benzophenone, 2,4,6-trimethylbenzophenone and benzophenone and 1-hydroxycyclohexyl phenyl ketone and benzophenone.

[0284] Suitable systems are described, for example, in EP 355028, EP 441221, EP 0789724, US 5516453 and US 5498659 and / or are commercially available, for example in the case of UV initiators from Omnirad and IGM Resins (for example Esacure TZM, Esacure TZT, Omnirad 4MBZ).

[0285] The present application also relates to an aqueous coating composition, which contains

[0286] a) a binder polymer in the form of an aqueous polymer latex as defined herein; and

[0287] b) at least one further ingredient which is conventionally used in aqueous coating compositions and is not a binder.

[0288] The aqueous coating composition of the present application can be formulated as a clear coating or as a paint. In the latter case, the aqueous coating composition contains, in addition to the polymer latex, at least one of an inorganic pigment and an inorganic filler. In particular, the aqueous coating composition contains at least one inorganic pigment, in particular at least one inorganic pigment, which imparts a white shade or color to the coating obtained when the aqueous coating composition is used for coating a substrate.

[0289] Pigments for the purposes of the present application are almost insoluble, finely dispersed, organic or preferably inorganic colorants according to the definition in the German standard DIN 55944:2003-11. Examples of pigments are in particular inorganic pigments, such as white pigments like titanium dioxide (C.I. Pigment White 6), but also colored pigments, for example

[0290] - black pigments, such as iron oxide black (C.I. Pigment Black 11), iron manganese black, spinel black (C.I. Pigment Black 27), carbon black (C.I. Pigment Black 7);

[0291] - colored pigments, such as chromium oxide, hydrated chromium oxide green; chromium green (C.I. Pigment Green 48); cobalt green (C.I. Pigment Green 50); ultramarine green; cobalt blue (C.I. Pigment Blue 28 and 36); ultramarine blue, iron blue (C.I. Pigment Blue 27), manganese blue, ultramarine violet, cobalt violet, manganese violet, iron oxide red (C.I. Pigment Red 101); cadmium sulfoselenide (C.I. Pigment Red 108); molybdate red (C.I. Pigment Red 104); ultramarine red,

[0292] - iron oxide brown, mixed brown, spinel and corundum phases (C.I. Pigment Brown 24, 29 and 31), chromium orange;

[0293] - iron oxide yellow (C.I. Pigment Yellow 42); nickel titanium yellow (C.I. Pigment Yellow 53; C.I. Pigment Yellow 157 and 164); chromium titanium yellow; cadmium sulfide and cadmium zinc sulfide (C.I. Pigment Yellow 37 and 35); chromium yellow (C.I. Pigment Yellow 34), zinc yellow, alkaline earth metal chromates; Naples yellow; bismuth vanadate (C.I. Pigment Yellow 184);

[0294] - interference pigments, such as metallic effect pigments based on coated metal flakes, pearlescent pigments based on mica flakes coated with metal oxides, and liquid crystal pigments.

[0295] The aqueous coating compositions can also contain one or more fillers. Examples of suitable fillers are in particular inorganic fillers, such as aluminosilicates, e.g. feldspar, silicates, e.g. kaolin, talc, mica, magnesite, alkaline earth metal carbonates, such as calcium carbonate (e.g. in the form of calcite or chalk), magnesium carbonate, dolomite, alkaline earth metal sulfates, such as calcium sulfate, silica and the like. In the coating compositions of the present application, finely divided fillers are naturally preferred. The fillers can be used in the form of individual components. In practice, however, it has been found that filler mixtures are particularly useful, such as calcium carbonate / kaolin, calcium carbonate / talc. Gloss lacquers usually contain only small amounts of very finely divided fillers or no fillers at all. Fillers also include matting agents which significantly impair the gloss as desired. Matting agents are usually transparent and can be organic or inorganic. Examples of matting agents are inorganic silicates, such as the Syloid® brand from W. R. Grace & Company and the Acematt® brand from Evonik GmbH. Organic matting agents are available, for example, from BYK-Chemie GmbH under the Ceraflour® and Ceramat® brands and from Deuteron GmbH under the Deuteron MK® brand.

[0296] The proportion of pigments and fillers in the aqueous coating compositions can be described by the pigment volume concentration (PVC) in a manner known per se. The PVC describes the ratio of the volume of pigments (VP) and the volume of fillers (VF) in percent relative to the total volume, which consists of the volume of the binder (VB), the volume of the pigments (VP) and the volume of the fillers (VF) in the dried coating film: PVC [%] = (VP + VF) x 100 / (VP + VF + VB).

[0297] If the aqueous coating compositions are formulated as lacquers, they usually have a pigment volume concentration (PVC) of at least 5%, in particular at least 10%, and will typically not exceed 90%, in particular 85%. In a preferred embodiment group, the PVC will not exceed a value of 60%, in particular 50%, and in particular in the range from 5% to 60% or 5% to 50%. However, the inventive effect of the polymer dispersions also manifests itself in varnishes, which typically have a pigment / filler content of less than 5% by weight based on the varnish and accordingly a PVC of less than 5%. In yet another embodiment group, the PVC will be in the range from > 60% to 90%, in particular in the range from 65% to 85%.

[0298] According to one embodiment group, the aqueous coating compositions of the present application are designed as paints containing white pigments - i.e. they comprise at least one white pigment and optionally one or more fillers. As white pigments they particularly include titanium dioxide (preferably in rutile form), optionally in combination with one or more fillers. Particularly preferably, the coating compositions of the present application comprise white pigments, more particularly titanium dioxide (preferably in rutile form) in combination with one or more fillers (such as e.g. chalk, talc or mixtures thereof).

[0299] In another preferred embodiment group, the aqueous coating compositions of the present application are designed as transparent coatings or wood stain formulations. In contrast to paints, transparent coatings are essentially free of pigments and fillers, while wood stains contain not much fillers, i.e. they have a PVC below 5%.

[0300] According to a specific embodiment group, the present application also relates to an aqueous coating composition (in the following also referred to as aqueous coating composition) comprising:

[0301] i) at least one aqueous polymer latex as defined above; and

[0302] ii) a titanium dioxide pigment.

[0303] According to a further specific embodiment group, the present application also relates to the use of an aqueous polymer latex as binder in an aqueous coating composition containing a titanium dioxide pigment.

[0304] In the above embodiments, the aqueous polymer latex is combined with a Ti02pigment slurry or paste. The Ti02concentration of the aqueous Ti02pigment slurry or paste used for the preparation of the aqueous coating composition will generally be in the range of 30% to 85% by weight, often 40% to 80% by weight, and in each case based on the total weight of the aqueous Ti02pigment slurry or paste. The titanium dioxide pigment of the aqueous dispersion used for the preparation of the pigment slurry or paste can be any Ti02pigment conventionally used in coating compositions, in particular aqueous coating compositions. Often, a Ti02pigment is used in which the Ti02particles are preferably in rutile form. In another preferred embodiment, the Ti02particles can also be coated with e.g. aluminum, silicon and zirconium compounds.

[0305] Generally, the weight ratio of polymer to titanium dioxide pigment is in the range of > 0.1 : 5.0 to < 5.0 : 0.1; preferably, the weight ratio of polymer to titanium dioxide pigment is in the range of > 0.5 : 5.0 to < 5.0 : 0.5; particularly more preferably, the weight ratio of polymer to titanium dioxide pigment is in the range of > 0,5 : 3.0 to < 3.0 : 0,5 and in particular in the range of > 0.5 : 1.5 to < 1.5 : 0.5.

[0306] Preferably, the titanium dioxide pigment has an average primary particle size in the range of > 0.1 pm to < 0.5 pm as determined by light scattering or by electron microscopy.

[0307] Typically, the aqueous coating composition further comprises at least one additive selected from the group consisting of thickeners, defoamers, leveling agents, film-forming aids, biocides, wetting or dispersing agents, fillers and coalescing agents.

[0308] The aqueous coating composition can be simply prepared by mixing the Ti02pigment powder or an aqueous slurry or paste of the Ti02pigment with the aqueous polymer latex of the present application, preferably by applying shear to the mixture, for example by using a dissolver conventionally used for the preparation of aqueous paints. It is also possible to prepare an aqueous slurry or paste of the Ti02pigment and the aqueous polymer latex of the present application and then to incorporate it into or mix it with a further polymer latex of the present application or any other polymer latex binder.

[0309] The aqueous dispersion of the polymer composite can also be prepared by incorporating the aqueous polymer latex of the present application as a binder or co-binder into an aqueous base formulation of a paint already containing the Ti02pigment, for example by mixing the aqueous polymer latex of the present application with the pigment formulation already containing further additives conventionally used in the paint formulation.

[0310] In order to stabilize the Ti02pigment particles in the aqueous pigment slurry or paste, the mixing can optionally be carried out in the presence of additives conventionally used in aqueous pigment slurries or pastes, such as dispersants. Suitable dispersants include, but are not limited to, for example, polyphosphates such as sodium, potassium or ammonium polyphosphates, alkali metal and ammonium salts of acrylic acid homopolymers or copolymers or maleic anhydride polymers, polyphosphonates such as sodium 1-hydroxyethane-1,1-diphosphonate, and naphthalenesulfonates, in particular the sodium salts thereof.

[0311] The polymer concentration in the aqueous polymer latex used for the preparation of the aqueous dispersion of the polymer composite is generally in the range of 10 to 70% by weight, preferably 20 to 65% by weight and most preferably 30 to 60% by weight, based on the total weight of the aqueous polymer latex.

[0312] In addition to the polymer latex of the present application and the titanium dioxide pigment and optionally a conventional binder, the aqueous coating composition can also contain one or more pigments and / or fillers different from the Ti02pigment, as described above.

[0313] Preferably, the aqueous coating composition comprises at least one aqueous polymer latex as defined herein, further comprising a rheology modifier. Suitable rheology modifiers include associative thickener polymers and non-associative rheology modifiers. The aqueous liquid composition preferably comprises a thickener selected from the group consisting of associative thickeners and non-associative thickeners and combinations thereof.

[0314] Associative thickener polymers are well known and often described in scientific literature, for example in E.J. Schaller et al., in Handbook of Coating Additives, Vol. 2 (Ed. L.J. Calbo), Marcel Decker 192, pages 105-164, “Associative Thickeners”, J. Bieleman in Additives for Coatings (Ed. J. Bielemann), Wiley 2000, pages 50 - 58, “PUR-Verdicker”. NiSAT thickener polymers of the HEUR and HMPE type are also described in patent literature such as US 4,079,028, US 4155,892, EP 61822, EP 307775, WO 96 / 31550, EP 612329, EP 1013264, EP 1541643, EP 1584331, EP 2184304, DE 4137247, DE 102004008015, DE 102004031786, US 2011 / 0166291 and WO 2012 / 052508. In addition to this, associative thickener polymers are commercially available.

[0315] The associative thickener polymers include anionic acrylate thickener polymers, so-called HASE polymers (hydrophobically modified polyacrylate thickeners), which are copolymers of acrylic acid and alkyl acrylate monomers, wherein the alkyl group of the alkyl acrylate can have 6 to 24 carbon atoms. The associative thickener polymers also include non-ionic associative thickeners, so-called NiSAT thickeners (non-ionic synthetic associative thickeners), which are typically linear or branched block copolymers having at least one internal hydrophilic moiety, in particular a polyether moiety, especially at least one polyethylene oxide moiety, and two or more terminal hydrocarbyl groups each having at least 4 carbon atoms, in particular 4 to 24 carbon atoms, such as linear or branched alkyl groups having 4 to 24 carbon atoms or alkyl- substituted phenyl groups having 7 to 24 carbon atoms. The NiSAT thickeners include hydrophobically modified polyethylene oxide urethane rheology modifiers (also known as HEUR or PUR thickeners) and hydrophobically modified polyethylene oxides (which are also known as HMPEs).

[0316] The amount of associative thickener polymers will depend on the desired viscosity profile and is often in the range of 0.05% to 2.5% by weight, in particular 0.1% to 2% by weight, and especially 0.2% to 2% by weight of the latex paint based.

[0317] Suitable non-associative rheology modifiers are in particular cellulose-based thickeners, especially hydroxyethyl cellulose, but also thickeners based on acrylate emulsions (ASEs). Among the non-associative rheology modifiers, preference is given to non-associative cellulose-based thickeners.

[0318] The total amount of thickener polymers will depend on the desired viscosity profile and is often in the range of 0.05% to 6% by weight, in particular 0.1% to 5.5% by weight, and especially 0.15% to 5% by weight of the latex paint based.

[0319] The aqueous coating compositions according to the application can also comprise conventional auxiliaries. The conventional auxiliaries will depend in a well-known manner on the type of coating and include, but are not limited to:

[0320] - wetting agents or dispersants,

[0321] - film-forming aids, also known as coalescing agents,

[0322] - levelling agents,

[0323] - UV stabilizers,

[0324] - biocides and

[0325] - defoamers / de-aerators.

[0326] Suitable wetting or dispersing agents are, for example, sodium, potassium or ammonium polyphosphates, alkali metal and ammonium salts of acrylic acid copolymers or maleic anhydride copolymers, polyphosphonates such as sodium 1-hydroxyethane-1,1-diphosphonate, and naphthalenesulfonates, in particular the sodium salts thereof.

[0327] Suitable film-forming assistants are solvents and plasticizers. Plasticizers have a lower volatility compared to solvents and preferably have a boiling point above 250 °C at 1013 mbar, whereas solvents have a higher volatility than plasticizers and preferably have a boiling point below 250 °C at 1013 mbar. Suitable film-forming assistants are, for example, white spirit, pine oil, propylene glycol, ethylene glycol, butylene glycol, butylene glycol acetate, butylene glycol diacetate, butyl diglycol, butyl carbitol, 1-methoxy-2-propanol, 2,2,2-trimethyl-1,3-pentanediol monoisobutyrate (Texanol®), and glycol ethers and esters, which are commercially available, for example, under the names Solvenon® and Lusolvan® and Loxanol® from BASF SE and under the trade name Dowanol® from Dow. The amount is preferably < 5% by weight and more preferably < 1 % by weight, based on the total formulation. Formulations without film-forming assistants are also entirely possible. Frequently, the coating composition does not require any film-forming assistants.

[0328] Further suitable assistants and components are described, for example, by J. Bieleman in "Additives for Coatings", Wiley-VCH [Wiley-VCH Verlag], Weinheim 2000; by T. C. Patton in "Paint Flow and Pigment Dispersions", 2nd Edition, John Wiley & Sons [John Wiley & Sons, Inc.], New York 1978; and by M. Schwartz and R. Baumstark in "Water based Acrylates for Decorative Coatings", Curt R. Vincentz Verlag [Curt R. Vincentz Verlag GmbH & Co. KG], Hanover 2001.

[0329] Preferably, the aqueous coating composition contains not more than 5% by weight, in particular not more than 1% by weight, of organic solvents, based on the total weight of the aqueous coating composition. Herein, the term "solvent" refers to organic liquid compounds having a boiling point of less than 250°C at 1013 mbar. In a preferred embodiment group, the total amount of such organic solvents is not more than 0.5% by weight.

[0330] The aqueous coating composition of the present application can also be formulated as a VOC-free paint. In this case, the concentration of volatile compounds in the coating composition is typically below 0.5% by weight, preferably below 0.1 wt.-%, more preferably below 0.05 wt.-%, based on the total amount of the aqueous coating composition. For the present application, volatile compounds are compounds having a boiling point of less than 250°C at 1013 mbar.

[0331] The aqueous coating composition of the present application is particularly useful in architectural coatings, i.e. for coating the exterior or interior parts of a building. In this case, the substrate can be a mineral substrate, such as plaster of Paris, gypsum, gypsum board or concrete, wood, wood-based materials, metal, wall paper or plastic, such as PVC.

[0332] The aqueous coating composition can be applied to the substrate to be coated in a conventional manner, for example by applying it with a brush or a roller, by spraying, by dipping, by roll coating, or by bar coating onto the desired substrate. The preferred application is by brush and / or by roller.

[0333] Generally, the coating of the substrate is carried out in such a way that the substrate is first coated with the aqueous coating composition of the present application and that the aqueous coating thus obtained is then subjected to a drying step, especially in a temperature range of > -10°C and < +50°C, advantageously > +5°C and < +40°C and especially advantageously > +10°C and < +35°C.

[0334] The substrate coated with the aqueous coating composition of the present application has excellent hardness, good adhesion properties such as high dry and wet alkali adhesion and intercoat adhesion, good opacity, good stain removal properties and low dust pick-up.

[0335] Examples

[0336] The present application will be illustrated by the following non-limiting examples:

[0337] 1. Abbreviations:

[0338] wt.% by weight

[0339] Herein and hereinafter, the terms "room temperature" and "ambient temperature" mean a temperature in the range of 22°C to 23°C.

[0340] 2. Analysis of the polymer latex

[0341] 2.1 Solid content

[0342] The solid content is determined by drying a defined amount of the aqueous polymer dispersion (about 2 g) in an aluminum crucible with an inner diameter of about 5 cm to constant weight at 130 °C in a drying cabinet (2 hours). Two separate measurements are made. The values reported in the examples are the average of the two measurements.

[0343] 2.2 Particle size

[0344] The average particle size of the polymer latex is determined by dynamic light scattering (DLS) using a Malvern HPPS according to the ISO 13321 :1996 standard as described above, if not stated otherwise.

[0345] 2.3 Glass transition temperature Tg

[0346] The glass transition temperature is determined by the DSC method (differential scanning calorimetry, 20 K / min, midpoint measurement) by a DSC instrument (Q2000 series from TA instruments) according to the ISO 11357-2:2013 standard as described above.

[0347] 2.4 pH measurement

[0348] The pH measurement is performed on the reaction mixture using a pH meter.

[0349] 3. Ingredients

[0350] The following ingredients are used in the examples of the present application:

[0351]

[0352] Isobutyl acrylate can be produced by a similar approach to the production of bio-isoamyl acrylate by transesterification of ethyl acrylate with isobutanol as described in WO 2022 / 018013. Isobutanol can be obtained by fermentation of carbohydrates with > 98% bio-carbon content.

[0353] Alpha-methylene-gamma-butyrolactone can be produced from itaconic acid by a biotechnological process similar to that described in PCT / EP2022077180. Itaconic acid is a commercial product with 100% bio-carbon and is produced from carbohydrates.

[0354] 4. Preparation examples

[0355] 4.1 Adhesive examples

[0356] Inventive Example E1

[0357] Adhesive based on a polymer with alpha-methylene-gamma-butyrolactone and isobutyl acrylate

[0358] A reactor equipped with a stirrer, a temperature controller, a nitrogen inlet and a variety of injection possibilities was charged with 244.3 g of deionized water, 27.3 g of a polystyrene seed dispersion (33 wt%, particle size: 30 nm). The reaction mixture was purged with nitrogen and heated to 85°C. At 85°C, 5.0 g of feed 2 were added. 5 min later, feed 1 and feed 2 were added within 180 min.

[0359] Feed 1 : 400.5 g of deionized water, 18.5 g of Dowfax 2A1, 20.8 g of Lutensol TO 82, 6.9 g of acrylic acid, 13.9 g of acrylamide (50 wt% aqueous solution), 152.7 g of alpha-methylene-gamma-butyrolactone, 527.4 g of isobutyl acrylate.

[0360] Feed 2: 19.8 g of an aqueous sodium persulfate solution (7 wt%).

[0361] The reaction mixture was post-polymerized at 85°C for 30 min. Then feed 3 and feed 4 were added within 60 min.

[0362] Feed 3: 6.9 g of an aqueous tert-butyl hydroperoxide solution (10 wt%).

[0363] Feed 4: 6.2 g of an aqueous Rongalit C solution (10 wt%).

[0364] The reaction mixture was then allowed to cool to ambient temperature and neutralized to pH 8-9 with sodium hydroxide.

[0365] Tg (dried dispersion): 19°C

[0366] Average particle size: 133 nm

[0367] Solid content: 45.9 wt%

[0368] Inventive Example E2

[0369] Adhesive based on a polymer with alpha-methylene-gamma-butyrolactone, isobutyl acrylate and methyl methacrylate

[0370] A reactor, equipped with stirrer, temperature controller, nitrogen inlet and multiple injection possibilities, was charged with 244.3 g of deionized water, 27.3 g of a polystyrene seed dispersion (33 wt%, particle size: 30 nm). The reaction mixture was purged with nitrogen and heated to 85 °C. At 85 °C, 5.0 g of Feed 2 were added. 5 min later, Feed 1 and Feed 2 were added within 180 min.

[0371] Feed 1 : 400.5 g of deionized water, 18.5 g of Dowfax 2A1, 20.8 g of Lutensol TO 82, 6.9 g of acrylic acid, 13.9 g of acrylamide (50 wt% aqueous solution), 107.6 g of alpha-methylene-gamma-butyrolactone, 100.6 g of methyl methacrylate, 471.9 g of isobutyl acrylate.

[0372] Feed 2: 19.8 g of an aqueous sodium persulfate solution (7 wt%).

[0373] The reaction mixture was post-polymerized at 85 °C for 30 min. Then Feed 3 and Feed 4 were added within 60 min.

[0374] Feed 3: 6.9 g of an aqueous tert-butyl hydroperoxide solution (10 wt%).

[0375] Feed 4: 6.2 g of an aqueous Rongalit C solution (10 wt%).

[0376] The reaction mixture was then allowed to cool to ambient temperature and neutralized to pH 8-9 with sodium hydroxide.

[0377] Tg (dried dispersion): 21 °C

[0378] Average particle size: 130 nm

[0379] Solid content: 46.5 wt%

[0380] Comparative Example C1

[0381] Adhesive based on a polymer with n-butyl acrylate and methyl methacrylate

[0382] A reactor, equipped with stirrer, temperature controller, nitrogen inlet and multiple injection possibilities, was charged with 244.3 g of deionized water, 27.3 g of a polystyrene seed dispersion (33 wt%, particle size: 30 nm). The reaction mixture was purged with nitrogen and heated to 85 °C. At 85 °C, 5.0 g of Feed 2 were added. 5 min later, Feed 1 and Feed 2 were added within 180 min.

[0383] Feed 1 : 400.5 g of deionized water, 18.5 g of Dowfax 2A1, 20.8 g of Lutensol TO 82, 6.9 g of acrylic acid, 13.9 g of acrylamide (50 wt% aqueous solution), 346.4 g of methyl methacrylate, 332.6 g of n-butyl acrylate.

[0384] Feed 2: 19.8 g of an aqueous sodium persulfate solution (7 wt%).

[0385] The reaction mixture was post-polymerized at 85 °C for 30 min. Then feed 3 and feed 4 were added within 60 min.

[0386] Feed 3: 6.9 g of an aqueous tert-butyl hydroperoxide solution (10 wt%).

[0387] Feed 4: 6.2 g of an aqueous Rongalit C solution (10 wt%).

[0388] The reaction mixture was then cooled to ambient temperature and neutralized to pH 8-9 with sodium hydroxide.

[0389] Tg (dried dispersion): 20 °C

[0390] Average particle size: 125 nm

[0391] Solid content: 48.2 wt%

[0392] 4.2 Formulation Example

[0393] Inventive Example E3

[0394] Formulation of a semi-gloss paint with binder from Example E1

[0395] Mix 200.0 g of Kronos 4311 pigment with 15.0 g of water. Add 1.75 g of AMP-95 neutralizer (Angus Chemicals), 5.0 g of propylene glycol (Univar), 2.0 g of Foamstar 2420 defoamer (BASF), 10.0 g of Tamol 165 A dispersant (Dow), and 3.0 g of Hydropalat WE 3320 wetting agent (BASF) under low stirring speed. Add 1.5 g of Attagel 50 (BASF), 25.0 g of Minex 10 (Silicon Biotech) filler, 125.0 g of Kronos 4311 pigment, 73.9 g of water, and 20.0 g of Aquaflow NHS-310 (Ashland) nonionic associative thickener to a mixture at high stirring speed and mix for 30 min. Filter the mixture through a 400 µm filter and then add it to a combination of 527.0 g of binder from Example E1, 25.0 g of Ropaque Ultra E polymer pigment (Dow), and 2.0 g of Foamstar 2420 defoamer (BASF) and stir for 5 min. Add 9.0 g of Texanol coalescing agent (Eastman) and 9.0 g of Optifilm 400 coalescing agent (Eastman) and mix for 5 min. Then add 2.0 g of Proxel AQ biocide (Lonza), 3.0 g of Polyphase 663 fungicide (Troy), and 3.5 g of Rheolate CVS 10 nonionic associative thickener (Hymens) and mix for 5 min. Finally, add 2.5 g of Acrysol RM 895 nonionic associative thickener (Dow) and stir the mixture at medium speed for 30 min.

[0396] Example E4 of this invention

[0397] Formulations of semi-gloss varnishes containing adhesives from Example E2

[0398] Example C1 200.0 g of Kronos 4311 pigment was mixed with 15.0 g of water. At low stirring speed 1.75 g of AMP-95 neutralizer (Angus Chemical Company), 5.0 g of Propylene Glycol (Univar), 2.0 g of Foamstar 2420 defoamer (BASF), 10.0 g of Tamol 165 A dispersant (Dow) and 3.0 g of Hydropalat WE3320 wetting agent (BASF) were added. At high stirring speed 1.5 g of Attagel 50 (BASF), 25.0 g of Minex 10 (Silibiko) filler, 125.0 g of Kronos 4311 pigment, 81.4 g of water and 20.0 g of Aquaflow NHS-310 (Ashland) non-ionic associative thickener were added and mixed for 30 min. The mixture was filtered through a 400 pm filter and then added to a combination of 520.3 g of binder from Example E2, 25.0 g of Ropaque UltraE polymer pigment (Dow) and 2.0 g of Foamstar 2420 defoamer (BASF) and stirred for 5 min. 9.0 g of Texanol coalescent (Eastman) and 9.0 g of Optifilm 400 coalescent (Eastman) were added and mixed for 5 min. Then 2.0 g of Proxel AQ biocide (Lonza), 3.0 g of Polyphase 663 fungicide (Troy) and 3.5 g of Rheolate CVS 10 non-ionic associative thickener (Hermann Stauffer) were added and mixed for 5 min. Finally, 1.7 g of Acrysol RM 895 non-ionic associative thickener (Dow) was added and the mixture was stirred for 30 min at medium speed.

[0399] Comparative Example C2

[0400] Formulation of semi-gloss paint with binder from Example C1

[0401] Example D1 200.0 g of Kronos 4311 pigment was mixed with 15.0 g of water. At low stirring speed 1.75 g of AMP-95 neutralizer (Angus Chemical Company), 5.0 g of propylene glycol (Univar), 2.0 g of Foamstar 2420 defoamer (BASF), 10.0 g of Tamol 165 A dispersant (Dow) and 3.0 g of Hydropalat WE3320 wetting agent (BASF) were added. At high stirring speed 1.5 g of Attagel 50 (BASF), 25.0 g of Minex 10 (Silibond) filler, 125.0 g of Kronos 4311 pigment, 98.7 g of water and 20.0 g of Aquaflow NHS-310 (Ashland) non-ionic associative thickener were added and mixed for 30 min. The mixture was filtered through a 400 pm filter and then added to a combination of 502 g of binder from Example C1, 25.0 g of Ropaque Ultra E polymer pigment (Dow) and 2.0 g of Foamstar 2420 defoamer (BASF) and stirred for 5 min. 9.0 g of Texanol coalescent (Eastman) and 9.0 g of Optifilm 400 coalescent (Eastman) were added and mixed for 5 min. Then 2.0 g of Proxel AQ biocide (Lonza), 3.0 g of Polyphase 663 fungicide (Troy) and 3.0 g of Rheolate CVS 10 non-ionic associative thickener (Hermann Stauffer) were added and mixed for 5 min. Finally, 2.2 g of Acrysol RM 895 non-ionic associative thickener (Dow) were added and the mixture was stirred for 30 min at medium speed.

[0402] 4.3 Application properties

[0403] The following application properties were determined.

[0404] Gloss:

[0405] Coating films were prepared on Leneta 3B black and white sealed drawdown cards with a 3 mil drawdown bar. The films were dried at room temperature for 24 hours. Gloss was measured with a gloss meter at angles of 20°, 60° and 85°, respectively.

[0406] The results were as follows:

[0407]

[0408] Gloss of E4 was improved compared to C2.

[0409] High Shear Viscosity:

[0410] High shear viscosity was measured according to ASTM D4287 at 7 days after preparation. Results are as follows:

[0411]

[0412] All three samples had comparable results.

[0413] Opacity:

[0414] Coating films were prepared on Leneta 3B black and white opaque cards with a 3 mil drawdown bar. The films were dried at room temperature for 24 hours. Opacity was determined by spectrophotometry as the ratio of reflected light from the dried coating on the black portion to the white portion from the Leneta card. Opacity indicates the ability of the coating to cover the black surface. Results are as follows:

[0415]

[0416] E3 and E4 had a slight improvement in opacity compared to C2.

[0417] Dry Alkyd Adhesion:

[0418] Dry alkyd adhesion was measured according to ASTM D3359. Evaluation was performed after 7 days. Dry alkyd adhesion was rated on a scale of 0 to 5, where a rating of 0 = complete removal of film and a rating of 5 = no removal of film. Results are as follows:

[0419]

[0420] Rating of 0 = complete removal of film, Rating of 5 = no removal of film

[0421] E3 and E4 had a significant improvement in dry alkyd adhesion compared to C2.

[0422] Wet Alkyd Adhesion:

[0423] Wet alkyd adhesion was measured according to ASTM D3359. Evaluation was performed after 7 days. Wet alkyd adhesion was rated on a scale of 0 to 5, where a rating of 0 = complete removal of film and a rating of 5 = no removal of film. Results are as follows:

[0424]

[0425] Rating of 0 = complete removal of film, Rating of 5 = no removal of film

[0426] E3 and E4 had a significant improvement in wet alkyd adhesion compared to C2.

[0427] Dry Coating to Coating Adhesion:

[0428] Dry intercoat adhesion was measured according to ASTM D3359. Evaluation was performed after 7 days. Dry intercoat adhesion was rated on a scale of 0 to 5, where a rating of 0 = complete removal of film and a rating of 5 = no removal of film. Results are as follows:

[0429]

[0430] Rating 0 = complete removal of film, Rating 5 = no removal of film

[0431] All three samples had comparable results.

[0432] Wet intercoat adhesion:

[0433] Wet intercoat adhesion was measured according to ASTM D3359. Evaluation was performed after 7 days. Wet intercoat adhesion was rated on a scale of 0 to 5, where a rating of 0 = complete removal of film and a rating of 5 = no removal of film. Results are as follows:

[0434]

[0435] Rating 0 = complete removal of film, Rating 5 = no removal of film

[0436] All three samples had comparable results.

[0437] König pendulum hardness:

[0438] König pendulum hardness was measured according to ASTM D4366 on coatings prepared on aluminum as substrate. Evaluation was performed after 7 days. The results obtained, which are each an average of three measurements, are given in the table below.

[0439]

[0440] The hardness of E3 and E4 was significantly improved compared to C2.

[0441] Stain removal:

[0442] Stain removal was measured according to ASTM D4828.

[0443] With regard to the staining caused by pencil, lipstick, crayon, ballpoint pen, red wine, ketchup, coffee, mustard (visual inspection), the coating results of inventive examples E3 and E4 were comparable to the coating results of comparative example C2.

[0444] Dust pick-up:

[0445] The surfaces of the yellow pine were scuffed with water and allowed to dry overnight. The substrates were divided into sections according to the number of samples to be tested. The test paint samples were applied using the appropriate brush at a natural application rate. The coatings were allowed to cure at room temperature for a period of 4 hours and 24 hours respectively. Half of the coated area was then covered with 2 inches of dry dirt (Arizona dirt or Carpet dirt). The panels were allowed to sit for 15 minutes, then they were tilted vertically and tapped to dislodge the dirt. The soiled areas of each sample were gently scrubbed (15 light strokes).

[0446] The dust build-up of the coatings from inventive examples E3 and E4 was reduced (visual assessment) compared to the coating from comparative example C2.

Claims

1. An aqueous polymer latex of a copolymer obtainable by aqueous emulsion polymerization of ethylenically unsaturated monomers M, which comprise i. 2 to 70 % by weight, based on the total amount of monomers M, of monomers M1 which are methylene-gamma-butyrolactone; ii. at least one monomer M2 in an amount of 20 to 95 % by weight, based on the total amount of monomers M, selected from C2-C 20 - alkyl esters and C5-C 20 - alkyl esters and C5-C - alkyl esters and C5-C iii. 0 to 40 % by weight, based on the total amount of monomers M, of at least one monomer M3 selected from the group consisting of tert-butyl acrylate, C1-C4-alkyl esters of methacrylic acid, cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate and monovinyl aromatic monomers and mixtures thereof; wherein the total amount of monomers M1 and M3 is in the range of 5 to 70 % by weight, based on the total amount of ethylenically unsaturated monomers M, and wherein the total amount of monomers M1, M2 and M3 is at least 85 % by weight, based on the total amount of ethylenically unsaturated monomers M.

2. The aqueous polymer latex of claim 1, wherein, The monomers M1 are alpha-methylene-gamma-butyrolactone.

3. The aqueous polymer latex of any of the preceding claims, wherein, The amount of methylene-gamma-butyrolactone is in the range of 5 to 40 % by weight, based on the total amount of monomers M.

4. The aqueous polymer latex of any of the preceding claims, wherein, The methylene-gamma-butyrolactone is of biological origin.

5. The aqueous polymer latex of any one of the preceding claims, wherein, The monomers M2 comprise isobutyl acrylate.

6. The aqueous polymer latex of claim 4, wherein, The carbon atom of at least the isobutyl group of isobutyl acrylate is of biological origin.

7. The aqueous polymer latex of any one of claims 4 and 5, wherein, The amount of isobutyl acrylate is in the range of 20 to 90 % by weight, based on the total amount of monomers M, preferably in the range of 20 to 85 % by weight.

8. The aqueous polymer latex of any of the preceding claims, wherein, The monomers M3 comprise or are methyl methacrylate, or wherein the monomers M3 comprise or are styrene.

9. The aqueous polymer latex of any of the preceding claims, wherein, The monomers M further comprise at least one monomer M4 selected from the group consisting of monoethylenically unsaturated monomers having an acidic group.

10. The aqueous polymer latex of any of the preceding claims, wherein, The monomers M further comprise at least one monoethylenically unsaturated non-ionic monomer M5 having a solubility in deionized water at 20 °C and 1 bar of at least 60 g / L.

11. The aqueous polymer latex of any of the preceding claims, wherein, The monomers M comprise not more than 1 % by weight, based on the total amount of monomers M, of ethylenically unsaturated monomers M7 having at least 2 non-conjugated ethylenically unsaturated double bonds.

12. The aqueous polymer latex of any of the preceding claims, wherein, The monomers M consist of i. 5 to 70 % by weight, based on the total amount of monomers M, of methylene-gamma-butyrolactone, in particular alpha-methylene-gamma-butyrolactone, as monomers M1 ; ii. 20 to 90 % by weight, based on the total amount of monomers M, of at least one monomer M2 comprising or being isobutyl acrylate; iii. 0 to 40 % by weight, based on the total amount of monomers M, of at least one monomer M3 selected from the group consisting of styrene, methyl methacrylate and combinations thereof; iv. 0.05 to 9.95 % by weight, based on the total amount of monomers M, of at least one monoethylenically unsaturated monomer M4 selected from the group consisting of monoethylenically unsaturated monomers having an acidic group; v. 0 to 9.95 % by weight, based on the total weight of the monomers M, of one or more non-ionic monomers M5 having a solubility in deionized water at 20 °C and 1 bar of at least 60 g / L.

13. The aqueous polymer latex of any of the preceding claims, wherein, The polymer particles comprise a polymer phase having a glass transition temperature Tgin the range of -25 °C to + 50 °C.

14. The aqueous polymer latex of any of the preceding claims, wherein, The polymer particles have a Z-average particle size in the range of 50 to 500 nm as determined by dynamic light scattering according to the ISO 13321 :1996 standard.

15. A process for producing the aqueous polymer latex as claimed in any of the preceding claims, which process comprises carrying out an aqueous emulsion polymerization of the monomers M.

16. Use of the aqueous polymer latex as claimed in any of claims 1 to 14 as a binder in an aqueous coating composition.

17. An aqueous coating composition, which contains a) a binder polymer in the form of the aqueous polymer latex as claimed in any of claims 1 to 14; and b) at least one further ingredient which is conventionally used in aqueous coating compositions and is not a binder.

18. The use of claim 16 or the composition of claim 17, wherein, The aqueous coating composition contains no more than 5% by weight of organic solvents.

19. The use of claim 16 or the composition of claim 17, wherein, The aqueous coating composition has a pigment volume concentration of at least 5%.

20. The use or composition of any one of claims 16 to 19, wherein, The aqueous coating composition is a latex paint, in particular a latex paint for architectural coatings, a wood coating or wood staining composition or a latex paint for interior coatings. The aqueous coating composition contains no more than 5% by weight of organic solvents. The aqueous coating composition has a pigment volume concentration of at least 5%. The aqueous coating composition is a latex paint, in particular a latex paint for architectural coatings, a wood coating or wood staining composition or a latex paint for interior coatings.

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