WO2025036648A1

WO2025036648A1 - Aqueous oxathiolanone group-containing polymer dispersion

Info

Publication number: WO2025036648A1
Application number: PCT/EP2024/070517
Authority: WO
Inventors: Arnold Leidner; Konrad Roschmann; Peter Rudolf
Original assignee: Basf Se
Priority date: 2023-08-11
Filing date: 2024-07-19
Publication date: 2025-02-20

Abstract

An aqueous dispersion comprising a polymeric compound A having at least one oxathiolanone group is provided, preferably a copolymer obtainable by a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula (II), wherein R¹ is H or CH₃, X is C₁-C₄-alkylene, and at least one monoethylenically unsaturated monomer M2, and the amount of the monomer M1 of formula (I) is at most 30 wt%, based on the total weight of the monomers M. The copolymer is suitable as a binder in a waterborne coating composition.

Description

Aqueous oxathiolanone group-containing polymer dispersion

Description

The present invention relates to an aqueous dispersion containing an oxathiolanone group- containing polymer, a process of preparing thereof and the use thereof. Further, the invention relates to a waterborne curable coating composition containing said polymer and to the use thereof to produce coatings.

Background of the invention

Aqueous polymer dispersions of polymerized ethylenically unsaturated monomers, also referred to as polymer latex, are fluid systems comprising dispersed polymer particles of a chain growth addition polymer in an aqueous medium. Depending on the polymer architecture of the dispersed polymer particles, the polymer dispersions may be used across a variety of technical applications. In particular, such polymers may be used as binders in waterborne coating or adhesive formulations.

Important requirements for such binders are that they provide good mechanical properties, like high mechanical strength or hardness to the coating or cohesion strength to adhesives, and, hence, good stability of the coatings and adhesives against mechanical impact. At the same time, the coating or adhesive must be elastic in order to compensate mechanical stress.

In order to increase the mechanical properties and chemical resistance of waterborne coatings and adhesives, polymer dispersions are usually cross-linked after film formation - either by the use of self-cross-linkable monomers or by the addition of a cross-linking agent reactive towards functional groups of the polymer latex.

Aqueous polyurethane dispersions based on acrylic polyols are known to provide good mechanical properties and chemical resistance. However, such systems need isocyanate- functional cross-linking agents. As NCO groups are sensitive to moisture, the polyisocyanate component should be applied in masked or shielded, for example hydrophobically modified, form.

Further, the use of a polyisocyanate may cause problems with toxicity, safety and noxiousness to the environment in general. Therefore, these problems impose restrictions with respect to handling, even in aqueous media.

Alternatives to polyurethane-forming isocyanate/alcohol systems are known. For example, cyclic carbonates react with amines to form urethanes and are referred to in the literature also as “NISO” or “NIPU”. US 2012/0316286 A1 discloses an aqueous dispersion based on a vinyl copolymer comprising a cyclic carbonate group and an emulsifier group as a binder, the binder being prepared in a solvent medium. However, such binders provide more hydrophilic properties, which may be of disadvantage, for example, in exterior coatings. Cured polyurethanes formed from a non-polymeric cyclic monothiocarbonate compound and diamines are described in WO 2019/034470 A1 and in WO 2019/034473 A1 . WO 2020/109053 A1 discloses a coating based on a compound having two oxathiolanone groups.

The application of oxthiolanone group-containing polymers is known, for example, in the field of electronic materials. JP 2007-178903 A discloses that 5-(methacryloyloxy)methyl-1 ,3- oxathiolane-2-one of formula

may be used as a comonomer for radical polymerization. Especially, a positive radiation sensitive resin composition for producing a plated shaped article, for example, a bump for integrated circuit element is described. The composition contains a cross-linked polymer, obtained by polymerizing p-isopropenylphenol, isobornylacrylate, benzylacrylate, t-butylacrylate, 1 ,6-hexanedioldiacrylate and 5-(methacryloyloxy)methyl-1 ,3-oxathiolane-2-one at 70 to 100°C. The S-containing unit is described to have improved adhesion property after cyan gold plating.

Aqueous dispersions based on monomers having an oxathiolanethione group are disclosed, for example, in EP 1233030 A1 and JP 07-062190 A.

Thus, there is still a need for an aqueous dispersion comprising polymeric compounds having water-stable S-containing units capable of cross-linking to form isocyanate-free polymeric films with urethane groups having satisfactory performance such as sufficient flexibility, good filmforming properties as well as suitable mechanical properties, like sufficient hardness or tackiness, for various applications in coatings and adhesives.

Therefore, it is an object of the present invention to provide an aqueous dispersion comprising a polymeric compound, having S-containing units suitably used as a binder capable of providing a coating or adhesive having urethane groups while the use of isocyanates is avoided. The coating or adhesive should have, for example, sufficient flexibility and suitable mechanical properties, like sufficient hardness or tackiness. The process of preparing an aqueous dispersion of a polymeric compound having S-containing units should be economic and flexible. The starting materials should be as safe as possible and highly reactive towards amines, and if possible, cure at ambient temperature.

Further, it is an object to provide a curable coating composition comprising an aqueous dispersion of a polymeric compound having S-containing units, capable of providing a coating having urethane groups while the use of isocyanates is avoided. Further, the storage stability of the curable coating composition should meet commercial requirements.

Summary of the invention It has now been found that an aqueous dispersion containing a polymeric compound having an oxathiolanone group may be obtained as a binder capable of cross-linking via a polymer having urethane and thiol groups to an isocyanate-free polymer having urethane groups and thioether and/or disulfide groups.

Accordingly, in a first aspect the invention relates to an aqueous dispersion comprising a polymeric compound A having at least one unit derived from a monomer having at least one group of formula

In a further aspect, the invention relates to a process of preparing an aqueous dispersion, as defined in any aspect herein, the process comprising a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula

(II), as defined in any aspect herein, and at least one monoethylenically unsaturated monomer M2, as defined in any aspect herein, wherein the emulsion polymerization is carried out in the presence of a free-radical initiator and preferably an emulsifier.

In a further aspect, the invention relates to the use of an aqueous dispersion, as defined in any aspect herein, as a cross-linking agent or as a constituent in a curable waterborne coating or adhesive composition.

In a further aspect, the invention relates to a waterborne curable coating composition, containing a) an aqueous dispersion, as defined in any aspect herein, b) a compound B having at least one amino group, selected from a primary amino group, a secondary amino group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form, and c) optionally a compound C having at least one functional group reactive towards a SH group.

In a further aspect, the invention relates to the use of a waterborne coating composition, as defined in any aspect herein, for preparing a coating on a substrate, preferably a decorative or industrial coating. In a further aspect, the invention relates to a coating, containing a hardened waterborne coating composition, as defined in any aspect herein, on a substrate, preferably a decorative or a protective coating.

In a further aspect, the invention relates to a process of producing a coating, the process comprising a) applying a waterborne coating composition, as defined in any aspect herein, to a substrate, and b) allowing the waterborne coating composition to cross-link to form the coating.

Detailed description of the invention

The terms “alkyl”, “alkylene”, “cycloalkyl”, “aryl”, “halogen” are known in the art and generally have the following meaning, if said groups are not further specified in specific embodiments mentioned below:

Alkyl, e.g., Ci-C₂2-alkyl, Ci-C₂o-alkyl, Ci-Ci₈-alkyl, Ci-Ci₂-alkyl, Ci-C-io-alkyl, Ci-C₈-alkyl, or Ci- C₄-alkyl, may be within the given limits of carbon atoms linear or branched, where possible. Examples are methyl (Me), ethyl (Et), n-propyl, isopropyl, n-butyl, 1 -methylpropyl, 2- methylpropyl, t-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethylpropyl, n-hexyl, 1 -methylhexyl, n- heptyl, 1 ,1 ,3,3-tetramethylbutyl, 1 -methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, n-nonyl, n- decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n- octadecyl, n-eicosyl, behenyl and constitutional isomers of the aforementioned n-alkyl radicals.

Alkylene, e.g., Ci-C₄-alkylene, C₂-C₄-alkylene or C₂-C₃-alkylene, may be derived from linear or branched alkyl, if possible, by abstracting a H atom from any terminal carbon atom of the alkyl.

Cycloalkyl, e.g., C₅-Ci₂-cycloalkyl, or C₃-Ci₂-cycloalkyl, include cycloalkyl groups and bicyclic groups, which may be unsubstituted or substituted with alkyl groups. Examples are cyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, cyclohexadecyl or 1 ,4-cyclohexylene-cyclohexyl. Bicyclic alkyl may be isobornyl (= 1 ,7,7-trimethylbicyclo[2.2.1]heptyl) or norbornyl (= bicyclo[2.2.1]heptyl). Cyclohexyl, isobornyl and norbornyl are preferred.

Aryl, e.g., C₆-Ci₈-aryl, or C₆-Ci₂-aryl, may be within the given limits of carbon atoms phenyl, fluorenyl, biphenylyl, terphenylyl or naphthyl, which may have a fused ring, such as in indanyl. Preferred examples are phenyl, 1-naphthyl, 2-naphthyl, 3- or 4-biphenylyl. Each aryl may be unsubstituted or substituted one or more times.

Halogen (Hal) denotes I, Br, Cl, or F, preferably Cl on alkyl and Cl or Br on aryl.

The term "C_n/C_m alkyl" denominates a mixture of two alkyl groups, one having n carbon atoms, while the other having m carbon atoms. The term “substituted” means “substituted one or more times with”, that is 1 to 3 times, where possible, preferably 1 or 2 times, more preferably 1 . If a substituent occurs more than once in a group, it may be different in each occurrence.

The term "(meth)acryloyl" or similar terms, as used herein, encompasses acryloyl, methacryloyl and mixtures thereof.

The term “oxathiolanone group”, as used herein, means a 1 ,3-oxathiolane-2-one group.

The term “ethylenically unsaturated group”, as used herein, means a non-aromatic ethylenically unsaturated group.

The term “(mono)ethylenically unsaturated monomer”, as used herein, means a non-aromatic monoethylenically unsaturated monomer, wherein the C=C double bond is susceptible to radical polymerization.

The term "non-ionic", as used herein with respect to compounds, especially monomers, means that the respective monomer does not carry any ionic functional group or any functional group, which can be converted by protonation or deprotonation into a ionic group.

The quantity for monomers of a polymer is based, unless otherwise explicitly stated, on 100 weight parts of all of the monomers.

The term “based on the total weight of the monomers”, as used herein with respect to the copolymer A1 , means all of the monomers used to form the copolymer A1 (monomers M including M1 and M2).

The term “latex” or “polymer latex”, as used herein, means a dispersion or emulsion of polymer particles formed in the presence of water and optionally a surfactant.

Unless otherwise stated, molecular weights of polymers refer herein to the weight-average molecular weight, measured by gel-permeation chromatography using a polystyrene standard.

The term “waterborne coating composition”, as used herein, means a liquid aqueous coating composition which, besides polymeric binders, optionally pigment and fillers, and further conventional formulation ingredients, contains water as the continuous phase in an amount sufficient to achieve flowability of the composition.

The term “any combination thereof’, as used herein, means two or more combinations thereof, either different kinds of one constituent or one group, i.e., different subgroups, or different kinds of a list of constituents or groups.

As used herein, the indefinite article “a” comprises the singular but also the plural, i.e., an indefinite article in respect to a component of a composition means that the component is a single compound or a plurality of compounds. If not stated otherwise, the indefinite article “a” and the expression “at least one” are used synonymously.

A compound A is a polymeric compound containing at least one unit derived from a monomer having a group of formula (I).

More preferably, the compound A is a polymeric compound containing at least one unit derived from a monomer M1 having a group of formula

(II), wherein

R¹ is H or methyl, and

X is Ci-C₄-alkylene.

The polymeric compound is preferably a copolymer A1 containing a unit derived from a monomer M1 of formula (II) and at least one further unit derived from a monoethylenically unsaturated comonomer M2.

The polymeric compound is preferably a copolymer A1 , obtainable by emulsion polymerization of a monomer M1 of formula (II) and at least one further monoethylenically unsaturated comonomer M2.

The amount of the monomer M1 may be varied, it may be up to 30 wt%, based on the total weight of the monomers M.

Therefore, preferred is an aqueous dispersion, wherein the compound A is a copolymer A1 , containing units derived from a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula (II), wherein R¹ is H or methyl,

X is Ci-C₄-alkylene, and at least one monoethylenically unsaturated monomer M2, wherein the amount of the monomer M1 of formula (I) is at most 30 wt%, based on the total weight of the monomers.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the compound A is a copolymer A1 , obtainable by a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula

(II), wherein

R¹ is H or methyl,

Preferred is a monomer M1 of formula

(II), wherein

R¹ is H or CH₃, especially CH₃; and

X is Ci-C₄-alkyl.

Further preferred is a monomer M1 of formula (II), wherein X is methylene or ethylene, especially methylene.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the compound A is a copolymer A1 , obtainable by emulsion polymerization process of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula

(II), wherein

R¹ is methyl,

X is methylene or ethylene, and at least one monoethylenically unsaturated monomer M2.

More preferred is a monomer M1 of formula (Ila)

The copolymer A1 is generally a copolymer containing a unit derived from the monomer M 1 of formula (II) and at least one further unit derived from a monomer M2, which is different from the monomer M1 of formula (II). The monomer M2 preferably does not contain an oxathiolanone group.

Typically, the copolymer A1 contains at least one further unit derived from an ethylenically unsaturated monomer M2.

The monoethylenically unsaturated monomer M2 may be an ethylenically unsaturated carboxylic acid or a salt thereof, an ethylenically unsaturated amide, an ethylenically unsaturated nitrile, an ethylenically unsaturated carboxylic ester, a vinyl aromatic compound, a vinyl heteroaromatic compound, a vinyl ester, a vinyl ether, an allyl ether, a vinyl halide and any combination thereof.

Examples of an ethylenically unsaturated carboxylic acid include C₃-C₆-monocarboxylic acids and salts thereof, like (meth)acrylic acid, crotonic acid, 2-ethylpropenoic acid, 2-propylpropenoic acid, 2-(meth)acryloxyacetic acid, as well as C₄-C₆-dicarboxylic acids, like itaconic acid, mesaconic acid, citraconic acid and fumaric acid. For example, the salts thereof include alkali metal.

Examples of an ethylenically unsaturated amide include (meth)acrylamide, N-substituted (meth)acrylamides, e.g. N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N- hexyl(meth)acrylamide, N-cyclohexyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N- phenyl(meth)acrylamide, N-benzyl(meth)acrylamide, N-ethyl-N-phenyl(meth)acrylamide, N-(4- hydroxyphenyl)(meth)acrylamide, N-isobutoxymethyl (meth)acrylamide and diacetone (meth)acrylamide.

Examples of an ethylenically unsaturated nitrile include (meth)acrylonitrile.

Examples of an ethylenically unsaturated carboxylic ester include (meth)acrylic esters such as: Ci-C₂2-alkylesters or C₅-Ci₂-cycloalkylesters, e.g., methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl-, pentyl, hexyl, cyclohexyl, 2-ethylhexyl, octyl, norbornyl or isobornyl ester; hydroxyalkyl esters, e.g., 2- hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl, 4- hydroxybutyl, 3,4-dihydroxybutyl or glycerol ester; haloalkylesters, e.g., 2-chloroethyl; aminoalkylesters, e.g., N,N’-dimethylaminoethyl, N,N’-dimethylaminopropyl or N,N’-dimethyl- aminobutyl; poly-C₂-C₄-alkylene oxide-containing esters, e.g., Ci-Ci₀-alkyl-poly-C₂-C₄-alkyleneoxide (meth)acrylate or poly-C₂-C₄-alkyleneoxide (meth)acrylate; epoxyalkyl esters, e.g., glycidyl, 2-glycidyloxyethyl, 2,3-epoxybutyl, 3,4-epoxy butyl, 2,3- epoxycyclohexyl, or 10, 11 -epoxyundecyl esters; aryl-containing esters, e.g., phenyl, benzyl-, o-, m- or p-hydroxyphenyl ester; maleic acid esters; itaconic acid esters; methylene succinic acid esters; butenolides and pentenolides, e.g., 2(5H)-furanone.

Examples of a vinyl aromatic compound include styrene, o-, m-, p-methylstyrene and 4-n- butylstyrene.

Examples of a heterocyclic vinyl compound include N-vinylpyrrolidone, N-vinylcaprolactam, 4- vinylpyridine, N-vinylimidazole and 5-methyl-3-vinyl-2-oxazolidinone (VMOX).

Examples of a vinyl ester include vinyl acetate, vinyl propionate and vinyl butyrate.

Examples of a vinyl ether or allyl ether include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, octyl vinyl ether, phenyl vinyl ether and a monoether of a polyethylene oxide or Ci-C₆- alkylpolyethyleneoxide with vinyl alcohol or allyl alcohol.

Examples of a vinyl halide include vinyl chloride and vinylidene chloride.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the at least one monoethylenically unsaturated monomer M2 is selected from an ethylenically unsaturated carboxylic acid or a salt thereof, an ethylenically unsaturated amide, an ethylenically unsaturated nitrile, an ethylenically unsaturated carboxylic ester, a vinyl aromatic compound, a vinyl heteroaromatic compound, a vinyl ester, a vinyl ether, an allyl ether, a vinyl halide and any combination thereof.

Preferably, the at least one monoethylenically unsaturated monomer M2 is selected from an ethylenically unsaturated carboxylic acid or salt thereof, an ethylenically unsaturated amide, an ethylenically unsaturated carboxylic ester, a vinyl aromatic compound and any combination thereof.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the at least one monoethylenically unsaturated monomer M2 is selected from an ethylenically unsaturated carboxylic acid or salt thereof, an ethylenically unsaturated carboxylic ester, a vinyl aromatic compound and any combination thereof.

The structural unit derived from the monomer M1 may be present in the copolymer A1 in an amount of up to 30 wt%, based on the total weight of the monomers M. A suitable amount of said structural unit may be dependent on the use. For example, an aqueous dispersion containing a copolymer A1 comprising a unit derived from the monomer M1 in an amount of 10 to 20 wt%, based on the total weight of the monomers M, may be suitably used as polymeric cross-linking agent with suitable polyamines. Further preferred is a copolymer A1 comprising 0.3 to 10 wt% of a unit derived from monomer M1 , more preferably 0.5 to 8 wt%, especially 1 to 7 wt%, based on the total weight of the monomers M.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the amount of the monomer M1 of formula (II) is of from 0.3 to 10 wt%, based on the total weight of the monomers M, preferably 0.5 to 8 wt%, especially 1 to 7 wt%.

The copolymer A1 may comprise a mixture of two or more monoethylenically unsaturated monomers M2, for example, a combination of

- an ethylenically unsaturated carboxylic ester and a vinyl aromatic compound and optionally an ethylenically unsaturated carboxylic acid; or

- an ethylenically unsaturated carboxylic ester and an ethylenically unsaturated carboxylic acid; or

- at least two different ethylenically unsaturated carboxylic esters.

The copolymer A1 preferably comprises 90 to 99.3 wt% of at least one unit derived from monomers M2, more preferably at least 92 wt%, based on the total weight of the monomers M.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the mixture of monoethylenically unsaturated monomers M comprise:

(i) 0.3 to 10 wt%, based on the total weight of monomers M, of monomer M1 of formula (II); and at least one monoethylenically unsaturated monomer M2, comprising

(ii) 90 to 99.9 wt%, based on the total weight of monomers M, of at least one monomer M2a, selected from a Ci-C₂2-alkylester of (meth)acrylic acid, a C₅-Ci₂-cycloalkylester of (meth)acrylic acid, a vinyl aromatic compound and any combination thereof;

(iii) 0 to 5 wt%, based on the total weight of monomers M, of at least one monomer M2b, selected from an ethylenically unsaturated carboxylic acid; and

(iv) 0 to 5 wt%, based on the total weight of monomers M, of at least one ethylenically unsaturated monomer M2c, which is non-ionic and different from the monomers M1 , M2a and M2b.

Suitable Ci-C₂2-alkyl esters of (meth)acrylic acid include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate n-pentyl (meth)acrylate, 2-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, 2- propylheptyl (meth)acrylate, lauryl (meth)acrylate, Ci₂/Ci₄-alkyl (meth)acrylate, Ci₃/Ci₅-alkyl (meth)acrylate (derived from C13/15- oxoalcohol), isotridecyl (meth)acrylate, Ci₆/Ci₈-alkyl (meth)acrylate, stearyl (meth)acrylate and behenyl (meth)acrylate.

Suitable C₅-Ci₂-cycloalkyl esters of (meth)acrylic acid include, but are not limited to, cyclohexyl (meth)acrylate, norbornyl (meth)acrylate and isobornyl (meth)acrylate. A suitable vinyl aromatic compound is styrene. The amount of a vinyl aromatic compound may vary in a broad range, dependant on the final application. Preferably, the amount of the vinyl aromatic compound, especially styrene, may be up to 60 wt%, based on the total weight of the monomers M, preferably 2 to 50 wt%. Alternatively preferred are 2 to 15 wt%, for example, for exterior-use applications.

Preferably, the monomers M2a comprise at least one monomer M2a-1 , whose homopolymer has a glass transition temperature T_g of more than 50°C, e.g., in the range of >50 to 200°C and at least one monomer M2a-2, whose homopolymer has a glass transition temperature T_g of not more than 50°C, e.g., in the range of -100 to +50°C. The glass transition temperatures T_g of the homopolymers of monomers M2a are well known and listed, for example, in publicly available database, e.g., from “Polymer Properties Database”, Crow® 2015-2021 , "https://polymerdatabase.com/polymer%20physics/Polymer%20Tg%20C.html”.

Apart from that the glass transition temperature T_g of the homopolymers of the monomers M2a as referred to herein can be determined experimentally by the differential scanning calorimetry (DSC) method according to ISO 11357-2:2013, preferably with sample preparation according to ISO 16805:2003.

Suitable monomers M2a-1 are in particular

- vinyl aromatic compounds, such as styrene,

- Ci-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, t-butyl methacrylate,

- C₅-Ci2-cycloalkyl esters of methacrylic acid, such as cyclohexyl methacrylate, norbornyl methacrylate and isobornyl methacrylate, and any combination thereof.

In particular, the monomers M2a-1 comprises methyl methacrylate, optionally in combination with one further monomer M2a-1 , which is preferably selected from C₂-C₄-alkyl esters of methacrylic acid and styrene. More preference is given to monomers M2a-1 , which comprises methyl methacrylate and/or styrene.

Suitable monomers M2a-2 are in particular C₂-Ci₂-alkyl ester of acrylic acid, such as ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, 2-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, isodecyl acrylate, 2- propyl heptyl acrylate and lauryl acrylate and any combination thereof. Preference is given to monomers M2a-b, which are selected from n-butyl acrylate, isobutyl acrylate, 2-ethylhexylacrylate and any combination thereof.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the monomer M2a comprises at least 90 wt%, based on the total weight of monomers M, of a combination of (ii-1) at least one monomer M2a-1 , selected from styrene, Ci-C₄-alkyl esters of methacrylic acid, C₅-Ci2-cycloalkyl esters of methacrylic acid and any combination thereof; and

(ii-2) at least one monomer M2a-2 selected from C₂-Ci₂-alkyl esters of acrylic acid.

If the monomers M2a comprise a combination of at least one monomer M2a-1 and at least one monomer M2a-2, the weight ratio of monomers M2a-1 to M2a-b is typically in the range of 3:7 to 7:3, in particular in the range of 4:6 to 6:4.

Accordingly, in a preferred aspect, the invention relates to an aqueous dispersion, wherein the monomer M2a-1 comprises methyl methacrylate and/or styrene.

In a further preferred aspect, the invention relates to an aqueous dispersion, wherein the monomer M2a-2 is selected from n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate and any combination thereof.

Suitable monomers M2b are selected from the group consisting of (meth)acrylic acid, itaconic acid and any combination thereof. Especially, the monomers M2b are selected from acrylic acid, methacrylic acid and any combination thereof.

The total amount of monomers M2b is preferably of from 0.2 to 4 wt%, more preferably of from 0.3 to 3 wt%, in particular of from 0.5 to 2 wt%, based on the total amount of monomers M.

The monomers M may comprise up to 5 wt% of ethylenically unsaturated non-ionic monomers M2c which are different from the monomers M1 , M2a and M2b. Preferably, the non-ionic monomers M2c have a water-solubility of at least 50 g/l, in particular at least 80 g/l or at least 100 g/l at 20°C and 1 bar in deionized water.

Examples of such monomers M2c include, but are not limited to

(iv-1) monomers M2c-1 , selected from a hydroxyalkyl ester of (meth)acrylic acid, for example, hydroxy-C₂-C₄-alkyl ester of (meth)acrylic acid;

(iv-2) monomers M2c-2, selected from an ethylenically unsaturated (meth)acrylamide, for example, (meth)acrylamide, and Ci-C₄-alkyl (meth)amide, such as N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-isopropyl (meth)acrylamide and N-butyl (meth)acrylamide; preferably (meth)acrylamide;

(iv-3) monomers M2c-3, selected from an epoxyalkyl ester of a (meth)acrylic acid, for example, glycidyl (meth)acrylate or 2-glycidyloxyethyl (meth)acrylate;

(iv-4) monomers M2c-4, selected from a monoester of a polyethylene-oxide or a Ci-C₆- alkylpolyethylene-oxide with (meth)acrylic acid, and a monoether of a polyethylene-oxide or Ci- C₆-alkylpolyethylene-oxide with vinyl alcohol or allyl alcohol, wherein the polyethylene-oxide and methylpolyethylene-oxide radicals generally have on average 5 to 100, in particular 10 to 50 ethylene-oxide repeating units.

It is understood that a copolymer A1 may contain an epoxy group-containing (meth)acrylate as monomer M2c-3, for example, glycidyl (meth)acrylate. The epoxy group may react as a functional group towards a SH group, i.e., the copolymer A1 may react as a possible compound C.

The total amount of monomers M2c-1 and M2c-2 does usually not exceed 4 wt%, in particular 3 wt%, based on the total weight of monomers M. In particular, the total amount of monomers M2c-1 , if present, is generally from 0.05 to 4 wt%, in particular 0.1 to 3 wt%, based on the total weight of the monomers M.

The amount of monomers M2c-3, if present, does usually not exceed 2 wt%, and frequently be in the range from 0.01 to 2 wt%, based on the total weight of monomers M.

The amount of monomers M2c-4, if present, does generally not exceed 5 wt% and, if present, are typically present in an amount of 0.1 to 5 wt%, especially in an amount of 0.2 to 3 wt%, based on the total weight of the monomers M.

A preferred aqueous dispersion contains a copolymer A1 , obtainable by emulsion polymerization of monomers, wherein the monomers M comprises or consists of the following monomers:

(i) 0.5 to 8 wt%, based on the total weight of monomers M, of a monomer M1 of formula (II);

(ii) 92 to 99.5 wt%, based on the total weight of monomers M, of at least one monomer M2a, which is a combination of monomers M2a-1 and M2a-2, preferably a combination of methyl methacrylate and/or styrene and one or two monomers M2a-2 or a combination of methyl methacrylate, styrene and one or two monomers M2a-2; wherein the monomers M2a-2 are selected from n-butyl acrylate, isobutyl acrylate and 2- ethylhexylacrylate and any combination thereof; and

(iii) 0 to 5 wt%, based on the total weight of monomers M, of at least one monomer M2b, selected from (meth)acrylic acid, itaconic acid and any combination thereof.

Further, the mixture of the ethylenically unsaturated monomers M may include an ethylenically unsaturated monomer carrying a functional group selected from a phosphate group, a phosphonate group, a sulfate group and a sulfonate group, preferably selected from a sulfonate group. An example of an ethylenically unsaturated monomer carrying a sulfonate group include 2-acrylamido-2-methylpropanesulfonic acid or a Na or K salt thereof. The amount of such ethylenically unsaturated monomer carrying a functional group may be of from 0.15 to 2 wt%, based on the total weight of the monomers M.

The aqueous polymer dispersion of the copolymer A1 may be prepared by emulsion polymerization of the monomers M in the presence of a free-radical initiator and preferably in the presence of an emulsifier.

Accordingly, in a further aspect, the invention relates to a process of preparing an aqueous dispersion, as defined in any aspect herein, the process comprising a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula

(II), as defined in in any aspect herein, and at least one monoethylenically unsaturated monomer M2, as defined in any aspect herein, wherein the emulsion polymerization is carried out in the presence of a free-radical initiator and preferably an emulsifier.

The term “free-radical aqueous emulsion polymerization”, as used herein, means that the polymerization of the monomers M is initiated by radicals formed by the decay of a free-radical initiator, whereby free radicals are formed in the polymerization mixture. The procedure for free- radical aqueous emulsion polymerizations of monomers in an aqueous medium has been extensively described and is therefore sufficiently familiar to the skilled person, as for example, described in D. Diederich, Chemie in unserer Zeit 24, 1990, pages 135 to 142. Typical procedures for aqueous emulsion polymerization of ethylenically unsaturated monomers are also described in the patent literature discussed in the introductory part of this application.

The radically initiated aqueous emulsion polymerization is typically carried out by emulsifying the ethylenically unsaturated monomers M in the aqueous medium which forms the aqueous phase, typically by use of surfactants, such as emulsifiers and/or protective colloids, and polymerizing this system using at least one initiator which decays by formation of radicals and thereby initiates the chain growth addition polymerization of the ethylenically unsaturated monomers M. The preparation of an aqueous polymer dispersion in accordance with the present invention may differ from this general procedure only in the specific use of the aforementioned monomers M. It will be appreciated here that the process shall, for the purposes of the present specification, also encompass the seed, staged, one-shot, and gradient regimes which are familiar to the skilled person.

The emulsifier and the protective colloids are distinct from each other by their weight-average molecular weight. Protective colloids usually are copolymers having molecular weights above 2000 g/mol up to 50,000, for example comprising a unit derived from a vinyl alcohol, a cellulosic derivative or a vinyl aromatic compound. The protective colloids are distinct from the instant copolymer A1 , as they are usually water-soluble.

If present, the surfactant is preferably an emulsifier. The surfactant may be an anionic, a cationic or a non-ionic emulsifier. Preferably, the emulsion polymerization is carried out in the presence of an anionic emulsifier.

The anionic emulsifier may principally be selected from any anionic emulsifier conventionally used in an emulsion polymerization of ethylenically unsaturated monomers M. Preferred anionic emulsifiers are in particular those carrying at least one sulfate, sulfonate, phosphate or phosphonate group. The anionic emulsifiers are typically used in the form of their alkali metal salts, especially of their sodium or ammonium salts.

Examples of preferred anionic emulsifiers which carry at least one sulfate or sulfonate group, are, for example,

- the salts, especially the alkali metal and ammonium salts, of alkyl sulfates, especially of C₈- C₂2-alkyl sulfates;

- the salts, especially the alkali metal and ammonium salts, of alkylethersulfates, i.e., of sulfuric monoesters of ethoxylated alkanols, especially of sulfuric monoesters of ethoxylated C₈-C₂2- alkanols, preferably having an ethoxylation level (EO level) in the range from 2 to 40;

- the salts, especially the alkali metal and ammonium salts, of sulfuric monoesters of ethoxylated alkylphenols, especially of sulfuric monoesters of ethoxylated C₄-Ci₈-alkylphenols (EO level preferably 3 to 40);

- the salts, especially the alkali metal and ammonium salts, of alkylsulfonic acids, especially of C₈-C₂2-alkylsulfonic acids;

- the salts, especially the alkali metal and ammonium salts, of dialkyl esters, especially di-C₄- Ci₈-alkyl esters of sulfosuccinic acid;

- the salts, especially the alkali metal and ammonium salts, of alkylbenzenesulfonic acids, especially of C₄-C₂2-alkylbenzenesulfonic acids;

- the salts, especially the alkali metal and ammonium salts, of mono- or disulfonated, alkylsubstituted diphenyl ethers, for example of bis(phenylsulfonic acid) ethers carrying a C₄-C₂₄- alkyl group on one or both aromatic rings.

Examples of anionic emulsifiers which carry a phosphate or phosphonate group, are, for example:

- the salts, especially the alkali metal and ammonium salts, of mono- and dialkyl phosphates, especially C₈-C₂2-alkyl phosphates;

- the salts, especially the alkali metal and ammonium salts, of 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 phosphoric monoesters of ethoxylated C₈- C₂2-alkanols, preferably having an ethoxylation level (EO level) in the range from 2 to 40, phosphoric monoesters of propoxylated C₈-C₂2-alkanols, preferably having a propoxylation level (PO level) in the range from 2 to 40, and phosphoric monoesters of ethoxylated-co- propoxylated C₈-C₂2-alkanols, preferably having an ethoxylation level (EO level) in the range from 1 to 20 and a propoxylation level of 1 to 20;

- the salts, especially the alkali metal and ammonium salts, of phosphoric monoesters of ethoxylated alkylphenols, especially phosphoric monoesters of ethoxylated C₄-Ci₈- alkylphenols (EO level preferably 3 to 40);

- the salts, especially the alkali metal and ammonium salts, of alkylphosphonic acids, especially C₈-C₂2-alkylphosphonic acids;

- the salts, especially the alkali metal and ammonium salts, of alkylbenzenephosphonic acids, especially C₄-C₂2-alkylbenzenephosphonic acids; Preferably, the emulsifier is an anionic emulsifier carrying at least one sulfate or sulfonate group. The at least one anionic emulsifier carrying at least one sulfate or sulfonate group, may be used alone or in a mixture with an anionic emulsifier carrying at least one phosphate or phosphonate group. In such a mixture, the amount of the at least one anionic emulsifier carrying at least one sulfate or sulfonate group is preferably at least 50 wt%, based on the total weight of anionic emulsifiers used in the instant process. In particular, the amount of anionic emulsifiers carrying at least one phosphate or phosphonate group does not exceed 20 wt%, based on the total weight of anionic emulsifiers used in the instant process.

Accordingly, in a preferred aspect, the invention relates to a process for preparing an aqueous dispersion containing a copolymer A1 , wherein the emulsifier is an anionic emulsifier, preferably carrying a sulfonate or sulfate group, especially in an amount of from 0.2 to 5 wt%.

Preferably, the emulsifier is at least one anionic emulsifier selected from an alkylether sulfate, an alkyl sulfate and any combination thereof.

Preferred anionic emulsifiers are selected from

- the salts, especially the alkali metal salts, of sulfuric monoesters of ethoxylated alkanols, especially of sulfuric monoesters of ethoxylated C₈-C₂2-alkanols, preferably having an ethoxylation level (EO level) in the range from 2 to 40; and any combination thereof.

In addition to the afore-mentioned anionic emulsifiers or alternatively, the surfactant used for the emulsion polymerization of the monomers M may comprise one or more non-ionic emulsifiers.

Suitable non-ionic emulsifiers are, e.g., araliphatic or aliphatic non-ionic emulsifiers, for example ethoxylated mono-, di- and trialkylphenols (EO level: 3 to 50, alkyl radical: C4-C10), ethoxylates of long-chain alcohols (EO level: 3 to 100, alkyl radical: C₈-C₃6), and polyethylene oxide/polypropylene oxide homo- and copolymers. These may comprise the alkylene oxide units copolymerized in random distribution or in the form of blocks. Very suitable examples are the EO/PO block copolymers. Preference is given to ethoxylates of C₈-C₃o-alkanols having a mean ethoxylation level of 5 to 100, especially ethoxylates of linear Ci₂-C₂o-alkanols having a mean ethoxylation level of 10 to 50.

The surfactants used in the instant process usually comprise not more than 30 wt%, especially not more than 20 wt%, of non-ionic emulsifiers, based on the total amount of surfactants used in the instant process. Especially a non-ionic emulsifier is not used. Combinations of at least one anionic surfactant and at least non-ionic surfactant may also be used. 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 50:50, in particular 98:2 to 60:40, especially in the range 95:5 to 70:30. Preferably, the amount of emulsifier, especially of an anionic emulsifier, is of from 0.2 to 5 wt%, especially from 0.3 to 4.5 wt%, in particular from 0.4 to 4 wt%, based on the total weight of monomers M to be polymerized.

Accordingly, in a preferred aspect, the invention relates to a process for preparing an aqueous dispersion containing a copolymer A1 , wherein the emulsifier is an anionic emulsifier, preferably carrying a sulfonate or sulfate group, in an amount of from 0.2 to 5 wt%, especially from 0.4 to 4 wt%, based on the total weight of monomers M.

Preferably, the major part, i.e., at least 80 wt% of the emulsifiers used, based on the total weight of the surfactants, especially emulsifiers, is added to the emulsion polymerization in parallel to the addition of the monomers. In particular, the monomers M are fed as an aqueous emulsion to the polymerization reaction which contains at least 80 wt% of the emulsifier used in the emulsion polymerization. Up to 20 wt% may be provided initially in water, for example, as a 1 to 20 wt% aqueous solution in water, preferably 2 to 15 wt%.

The free-radically initiated aqueous emulsion polymerization may be triggered by means of a free-radical initiator. These may, in principle, be a peroxide, an azo compound or a redox initiator system.

Peroxides may, in principle, 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, -potassium or ammonium salts, or organic peroxides such as alkyl hydroperoxides, for example t-butyl hydroperoxide, p-menthyl hydroperoxide or cumyl hydroperoxide and also dialkyl or diaryl peroxides such as di-t-butyl or di-cumyl peroxide.

Examples of an azo compound include 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4- dimethylvaleronitrile) and 2,2'-azobis(amidinopropyl) dihydrochloride.

Examples of a redox initiator system are combinations of an oxidizing compound and a reducing compound. Examples of an oxidizing compound include the peroxo-type initiators listed above. Examples of a reducing compound include sulfur compounds with a low oxidation state such as alkali metal sulfites, for example potassium and/or sodium sulfite, alkali metal hydrogensulfites, for example potassium and/or sodium hydrogensulfite, alkali metal metabisulfites, for example potassium and/or sodium metabisulfite, formaldehyde sulfoxylates, for example potassium and/or sodium formaldehyde sulfoxylate, alkali metal salts, specifically potassium and/or sodium salts of aliphatic sulfinic acids and alkali metal hydrogensulfides, for example potassium and/or sodium hydrogensulfide, salts of polyvalent metals, such as iron(ll) sulfate, iron(ll) ammonium sulfate, iron(ll) phosphate, ene diols such as dihydroxymaleic acid, benzoin and/or ascorbic acid, and reducing saccharides such as sorbose, glucose, fructose and/or dihydroxyacetone. A suitable example of a redox initiator system includes the combination of t-butyl hydroperoxide ascorbic acid. The weight ratio of oxidizing compound to the reducing compound is preferably 50:1 to 0.05:1. A preferred free-radical initiator is a peroxo-type or an azo-type initiator, more preferably an inorganic peroxide, especially a peroxodisulfate.

In general, the amount of the free-radical initiator used is of from 0.05 to 2 wt%, preferably 0.1 to 1 wt%, based on the total weight of monomers M.

The amount of free-radical initiator required for the emulsion polymerization of monomers M may be initially charged in the polymerization vessel completely. However, it is also possible to charge none of or merely a portion of the free-radical initiator, for example not more than 30 wt%, especially not more than 20 wt%, based on the total weight of the free-radical initiator and then to add any remaining amount of free-radical initiator to the free-radical polymerization reaction under polymerization conditions. Preferably, at least 70 wt%, in particular at least 80 wt%, especially at least 90 wt% or the total amount of the free-radical initiator are fed to the free-radical polymerization reaction in parallel to the addition of the monomers M. Feeding of the monomers M may be done according to the consumption, batch-wise in one or more portions or continuously with constant or varying flow rates during the free-radical emulsion polymerization of the monomers M.

Generally, the term "polymerization conditions" is understood to mean those temperatures and pressures under which the free-radically initiated aqueous emulsion polymerization proceeds at sufficient polymerization rate. They depend particularly on the free-radical initiator used. Advantageously, the type and amount of the free-radical initiator, polymerization temperature and polymerization pressure are selected, such that a sufficient amount of initiating radicals is always present to initiate or to maintain the polymerization reaction.

Preferably, the free-radical emulsion polymerization of the monomers M is performed by a so-called feed process, which means that at least 80 wt%, in particular at least 90 wt% or the total amount of the monomers M to be polymerized are metered to the polymerization reaction under polymerization conditions during a metering period. The monomers may be fed individually or preferably as a mixture. In each case the addition may be done in portions and preferably continuously with constant or varying feed rate. The metering period may depend on the production equipment and may vary from, e.g., 20 min to 12 hours. Frequently, the metering period may be in the range from 0.5 to 8 hours, especially from 1 to 6 hours.

The free-radical emulsion polymerization of the monomers M may be carried out in the presence of a seed latex. A seed latex is a polymer latex which is present in the aqueous polymerization medium before the polymerization of monomers M is started. The seed latex may help to better adjust the particle size or the final polymer latex obtained in the free-radical emulsion polymerization of the invention.

Principally, any polymer latex may serve as a seed latex. Preference is given to seed latices, where the particle size of the polymer particles is comparatively small. In particular, the Z average particle diameter of the polymer particles of the seed latex, as determined by dynamic light scattering (DLS) at 22°C according to EN ISO 22412:2017, is preferably in the range from 10 to 80 nm, in particular from 10 to 50 nm. Preferably, the polymer particles of the seed latex are made of ethylenically unsaturated monomers which comprise at least 95 wt%, based on the total weight of the monomers forming the seed latex, of one or more monomers selected from a C₂-Cio-alkyl acrylate, a Ci-C₄-alkyl methacrylate, a monoethylenically unsaturated nitrile, a vinyl aromatic compound and any combination thereof. In particular, the polymer particles of the seed latex are made of ethylenically unsaturated monomers which comprise at least 95 wt%, based on the total weight of the monomers forming the seed latex, of one or more monomers selected from a Ci-C₄-alkyl methacrylate, such as methyl methacrylate, a monoethylenically unsaturated nitrile, such as acrylonitrile, a vinyl aromatic monomer, such as styrene, and any combination thereof.

The seed latex is usually charged into the polymerization vessel before the polymerization of the monomers M is started, generally as an aqueous polymer dispersion. In particular, the seed latex is charged into the polymerization vessel followed by establishing the polymerization conditions, e.g., by heating the mixture to polymerization temperature. It may be beneficial to charge at least a portion of the free-radical initiator into the polymerization vessel before the addition of the monomers M is started. However, it is also possible to add the monomers M and the free-radical polymerization initiator in parallel to the polymerization vessel.

The amount of seed latex, calculated as solids, may be in the range of 0.01 to 10 wt%, preferably in the range of 0.05 to 5 wt%, in particular in the range of 0.05 to 3 wt%, based on the total weight of the monomers M to be polymerized.

The instant free-radical aqueous emulsion polymerization process is usually carried out at a temperature of from 0 to 170°C, preferably from 50 to 150°C, especially from 70 to 120°C. The aqueous emulsion polymerization may be conducted at a pressure of less than, equal to or greater than 1 atm (atmospheric pressure), and so the polymerization temperature may exceed 100°C and may be up to 170°C. Polymerization of the monomers is frequently carried out at ambient pressure, but it may also be carried out under elevated pressure. In this case, the pressure may assume values of 1 .2, 1 .5, 2, 5, 10, 15 bar (absolute) or even higher values. If the emulsion polymerization is conducted under reduced pressure, pressures of 950 mbar, frequently of 900 mbar and often 850 mbar (absolute) are established. Advantageously, the instant free-radical aqueous emulsion polymerization is conducted at ambient pressure (about 1 atm) with exclusion of oxygen, for example under an inert gas atmosphere, for example under nitrogen or argon.

The process for producing the instant polymer dispersion is usually a single stage polymerization or a multistage emulsion polymerization, preferably a single stage polymerization. In a single stage polymerization, the overall composition of the monomers M, which are fed to the polymerization reaction under polymerization conditions, remains the same or almost the same, while in a multistage emulsion polymerization the overall composition of the monomers M, which are fed to the polymerization reaction under polymerization conditions, is altered 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.

The polymerization of the monomers M may optionally be conducted in the presence of a chain transfer agent. Chain transfer agents are understood to mean compounds that transfer free radicals, and which reduce the molecular weight of the growing chain and/or which control chain growth in the polymerization.

Examples of a chain transfer agent include aliphatic and/or araliphatic halogen compounds, for example n-butyl chloride, n-butyl bromide, n-butyl iodide, methylene chloride, ethylene dichloride, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, carbon tetrabromide, benzyl chloride, benzyl bromide, organic thio compounds, such as primary, secondary or tertiary aliphatic thiols, for example ethanethiol, n-propanethiol, 2-propanethiol, n-butanethiol, 2-butanethiol, 2-methyl-2-propanethiol, n-pentanethiol, 2 pentanethiol, 3-pentanethiol, 2-methyl-2-butanethiol, 3-methyl-2-butanethiol, 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- butanethiol, n-heptanethiol and the isomeric compounds thereof, n-octanethiol and the isomeric compounds thereof, n nonanethiol and the isomeric compounds thereof, n-decanethiol and the isomeric compounds thereof, n-undecanethiol and the isomeric compounds thereof, n dodecanethiol and the isomeric compounds thereof, n-tridecanethiol and isomeric compounds thereof, substituted thiols, for example 2-hydroxyethanethiol, aromatic thiols such as benzenethiol, ortho-, meta- or para-methylbenzenethiol, alkyl esters of mercaptoacetic acid (thioglycolic acid), such as 2-ethylhexyl thioglycolate, alkyl esters of mercaptopropionic acid, such as octyl mercapto propionate, but also aliphatic and/or aromatic aldehydes, such as acetaldehyde, propionaldehyde and/or benzaldehyde, unsaturated fatty acids, such as oleic acid, dienes having nonconjugated double bonds, such as divinylmethane or vinylcyclohexane, or hydrocarbons having readily abstractable hydrogen atoms, for example toluene. It is possible to use mixtures of the afore-mentioned chain transfer agents that do not interfere with one another.

The amount of a chain transfer agent optionally used in the instant process, based on the total weight of monomers M, does generally not exceed 2 wt%, in particular 1 wt%. However, it is possible, that during a certain period of the polymerization reaction the amount of chain transfer agent added to the polymerization reaction may exceed the value of 2 wt% and may be as high as 8 wt%, in particular at most 4 wt%, based on the total weight of monomers M added to the polymerization reaction during said period. A chain transfer agent may be added initially or preferably in the course of the polymerization reaction.

It is frequently advantageous, when the aqueous polymer dispersion obtained on completion of polymerization of the monomers M is subjected to an after-treatment to reduce the residual monomer content. This after-treatment is effected either chemically, for example by completing the polymerization reaction using a more effective free-radical initiator system (known as postpolymerization), and/or physically, for example by stripping the aqueous polymer dispersion with steam or inert gas. The combination of chemical and physical after-treatment has the advantage that it removes not only the unconverted ethylenically unsaturated monomers, but also other disruptive volatile organic constituents (VOCs) from the aqueous polymer dispersion.

If needed, the aqueous polymer dispersion obtained by the instant process may be suitably neutralized prior to formulating it as a coating or adhesive composition. The neutralization may be achieved by neutralizing agents known to the skilled of the art after polymerization and/or during the polymerization, preferably after polymerization. Suitable neutralizing agents include organic tertiary amines, like triethylamine, diethylmethyl amine, dimethylpropyl amine, tributylamine, diisopropylethyl amine, triethanolamine or dimethyl ethanolamine, and alkali hydroxides, like NaOH or KOH. In particular, neutralization is achieved by using aqueous solutions of organic tertiary amines.

Preferably, the final aqueous polymer dispersion has a pH of at least pH 6, e.g., in the range of pH 7 to pH 9, as determined, for example, according to DIN EN 1262:2004-01 , prior to the use in the waterborne coating composition.

Accordingly, preferred is a process of preparing an aqueous dispersion, wherein the emulsion polymerization is carried out in the presence of a free-radical initiator and an emulsifier, wherein the emulsifier is an anionic emulsifier, selected from an alkylether sulfate, an alkyl sulfate and any combination thereof, the amount of the free-radical initiator is of from 0.05 to 2 wt%, based on the total weight of monomers M; the amount of emulsifier is of from 0.2 to 5 wt%, based on the total weight of monomers M; the process further comprising a step of adjusting the pH value of the aqueous dispersion to a pH of at least 6, preferably of from 7 to 9, as determined at 20°C and 1 bar.

Preferably, the particles of the copolymer A1 contained in the polymer dispersion have a hydrodynamic particle size, as determined by Hydrodynamic Chromatography fractionation (HDC), in the range of 50 to 500 nm, in particular in the range of 70 to 450 nm.

The particle size distribution of the copolymer particles contained in the polymer dispersion may be monomodal or almost monomodal, which means that the distribution function of the particle size has a single maximum and no particular shoulder. The particle size distribution of the copolymer particles contained in the polymer dispersion may also be bi- or polymodal or almost polymodal, which means that the distribution function of the particle size has at least two distinct maxima or at last one maximum and at least a pronounced shoulder.

The copolymer A1 usually has a glass transition temperature T_g in the range of -5 to +35°C, in particular in the range of 0 to 20°C, especially in the range of 0 to 15°C.

The instant aqueous dispersion generally has a solids content of from 20 to 75 wt%, obtained by the free-radical emulsion polymerization, preferably from 30 to 65 wt%, in particular from 40 to 60 wt%. The solids content describes the proportion of non-volatile fractions. The instant aqueous dispersion may be used as such, i.e., as obtained by the free-radical emulsion polymerization, or may be diluted to suitable solids content, suitable for the final application.

The aqueous dispersion comprising a copolymer A1 may be used for a variety of applications. Typically, the aqueous dispersion comprising the copolymer A1 is a constituent or a component of a waterborne coating or adhesive composition or as a polymeric cross-linking agent. In particular, the copolymer A1 may be used as a binder in a waterborne coating or adhesive composition, preferably applied as an aqueous dispersion.

Accordingly, in a further aspect, the invention relates to the use of a copolymer A1 , obtainable by a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula (II), wherein R¹ is H or methyl,

X is Ci-C₄-alkylene, and at least one monoethylenically unsaturated monomer M2, wherein the amount of the monomer M1 of formula (I) is at most 30 wt%, based on the total weight of the monomers, preferably from 0.3 to 10 wt%, as a binder in a waterborne coating composition.

In a further aspect, the invention relates to the use of an aqueous dispersion comprising a copolymer A1 , obtainable by a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula (II), wherein R¹ is H or methyl,

X is Ci-C₄-alkylene, and at least one monoethylenically unsaturated monomer M2, wherein the amount of the monomer M1 of formula (I) is at most 30 wt%, as a cross-linking agent or as a constituent in a curable waterborne coating or adhesive composition.

X is Ci-C₄-alkylene, and at least one monoethylenically unsaturated monomer M2, wherein the amount of the monomer M1 of formula (I) is at most 30 wt%, based on the total weight of the monomers, preferably from 10 to 20 wt%, as a cross-linking agent.

The aqueous dispersion comprising the copolymer A1 may be suitably used as a constituent of a waterborne coating composition, which is a curable coating composition containing further a compound B having at least one amino group selected from a primary amino group, a secondary amino group and any combination thereof, wherein the at least one amino group may be present in a masked, latently reactive form, and optionally a compound C having at least one functional group reactive towards a SH group.

Accordingly, in a further aspect, the invention relates to a waterborne coating composition, wherein the coating composition is a curable coating composition containing a) the aqueous dispersion, as defined in any aspect herein, b) a compound B having at least one amino group, selected from a primary amino group, a secondary amino group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form, and c) optionally a compound C having at least one functional group reactive towards a SH group.

A curable coating composition is generally understood as meaning a composition that comprises at least two polyfunctional constituents that react with one another with bond formation, thereby forming a polymer network. Accordingly, a curable coating composition preferably comprises, in addition to at least copolymer A1 , at least one compound B having at least 2 functional groups, especially at least two amino groups selected from a primary amino group, a secondary amino group and any combination thereof, or a compound B and at least one compound C having at least one functional group reactive towards a SH group.

A curable coating composition is preferred, wherein at least one compound of the compounds B and C is polyfunctional.

Accordingly, in a preferred aspect, the invention relates to a curable coating composition, with the proviso that

- the compound B is polyfunctional, in case the compound C is not present, or

- at least one compound of the compounds B and C is polyfunctional, in case the compound C is present.

A polyfunctional compound B may have two or more amino groups selected from a primary amino group, a secondary amino group and any combination thereof. Also, a polyfunctional compound B may have at least one amino group selected from a primary amino group, a secondary amino group and a combination thereof, and at least one ethylenically unsaturated group or a CEC bond-containing group.

A polyfunctional compound C may have two or more functional groups reactive towards a SH group. Also, a polyfunctional compound C may have at least one functional group reactive towards a group SH and an oxathiolanone group.

The aqueous polymer dispersion comprising the copolymer A1 may be used as the sole organic binder polymer in the waterborne coating formulation or as a co-binder in combination with other organic binder polymers. Preferably, the relative amount of the copolymer A1 in the waterborne coating formulations with respect to other organic binder polymers is at least 70 wt%, in particular at least 90 wt% or 100 wt%, based on the total weight of organic binder polymers present in the waterborne coating composition. Preferably, the waterborne coating composition contains only the aqueous polymer dispersion comprising the copolymer A1 as a binder.

The instant aqueous dispersion comprising the copolymer A1 may be diluted with water to a solids content, suitable for applying in the curable coating composition. The aqueous dispersion, as applied in the curable coating composition, has generally a solids content of from 5 to 60 wt%, dependent on the final application, preferably from 5 to 50 wt% or 5 to 30 wt%.

The curable coating composition comprises at least one compound B, also called curing compound B. The compound B has at least one amino group selected from a primary amino group, a secondary amino group and any combination thereof, wherein the amino group may be present in a masked, latently reactive form.

The compound B may be a monoamine or a polyamine.

Generally, the compound B does not comprise any oxathiolanone group.

The compound B may comprise further functional groups than a primary and/or a secondary amino group. The compound B may comprise, for example, a tertiary amino group, an ether group, a carboxylic ester group or an ethylenically unsaturated group. Preferably, compound B does not comprise any further functional group other than a tertiary amino group, an ether group, a carboxylic ester group or an ethylenically unsaturated group.

Preferably, the compound B is a compound having at least two primary amino groups, two secondary amino groups and any combination thereof, more preferably a compound having at least two primary amino groups.

The compound B is preferably a compound having at least one amino group selected from an aliphatic primary amino group, a cycloaliphatic primary amino group, an aliphatic secondary amino group, a cycloaliphatic secondary amino group and any combination thereof, preferably selected from an aliphatic primary group, a cycloaliphatic primary group and any combination thereof.

The compound B may be a low molecular-weight substance, i.e., one having a molecular weight below 500 g/mol, or an oligomeric or polymeric substance that has a molecular weight above 500 g/mol, preferably a low-molecular-weight compound having a molecular weight below 500 g/mol.

Depending on the application, for example for good polymer flexibility, it is preferable that the compound B and/or the optional compound C each contain at least one flexible spacer group. A flexible spacer group is a linear or branched linking group that has a molecular weight of at least 200 g/mol. The spacer group may be situated between two functional groups in the curing agent B. The spacer group is preferably selected from an alkylene group, a polyether group, a polycarbonate group, a polyester group, and a poly(meth)acrylate group. Examples of spacer groups are linear or branched alkylene groups having at least 15 carbon atoms; polyether groups of the general formula (Z¹-O)_r-, wherein Z¹ is C₂-C₄-alkylene and r is a number chosen such that the molecular weight of (Z¹-O)_r- is at least 200 g/mol; polycarbonate groups; polyester groups; and poly(meth)acrylate groups.

The compounds B include, for example, aliphatic and cycloaliphatic monoamines and polyamines, aromatic and araliphatic monoamines and polyamines, and also polymeric amines, for example polyethyleneimines, polyvinylamine, aminoplasts and polyamidoamines.

The compound B having one amino group is, for example, a monoalkylamine with a primary amino group or a dialkylamine with a secondary amino group.

Examples of a compound B having one amino group, selected from a primary amino or secondary amino group, are:

- monoalkylamines such as Ci-C₂o-alkylamines, di(Ci-C₂₀-)alkylamines, (dimethyl amino)propylamine, 3-(diethyl amino)propyl amine or 2-(diethylamino) ethylamine;

- cycloalkyl amines such as C₃-Ci₂-cycloalkyl amines;

- cyclic monoamines such as piperidine;

- etheramines such as 2-methoxyethylamine or 3-methoxypropylamine;

- di- or polyether amines such as di- or polyglycol amine or polyoxypropylene amine.

Preferred compounds B have an average of at least two primary or secondary amino groups or any combination thereof per molecule, e.g., two, three or four primary or secondary amino groups or any combination thereof per molecule. They may additionally contain one or more tertiary amino groups.

Examples of suitable polyamines are

- aliphatic polyamines such as ethylenediamine, propane-1 , 2-diamine, propane-1 , 3-diamine, pentamethylenediamine, 2-methyl-1 ,5-pentamethylenediamine, hexamethylenediamine, octamethylenediamine, 1 ,10-diaminodecane, 1 ,12-diaminododecane, diethylenetriamine (DETA), triethylenetetramine (TETA), dimethyl-diethylenetriamine (DMDETA), tetraethylenepentamine, 2,2-dimethyl-1 ,3-propanediamine, trimethylhexamethylenediamine, 1- (3-aminopropyl)-3-aminopropane, 1 ,3-bis(3-aminopropyl)propane, 4-ethyl-4-methylamino-1- octylamine, 1 ,2-dimethylethylenediamine (DMEDA), polyethyleneimine or polyvinylamine;

- cycloaliphatic diamines such as 1 ,2-diaminocyclohexane, 1 ,2-, 1 ,3-, 1 ,4-bis(aminomethyl)- cyclohexane, 1-methyl-2,4-diaminocyclohexane, N-cyclohexylpropylene-1 , 3-diamine, 4-(2- aminopropan-2-yl)-1-methylcyclohexan-1 -amine, isophoronediamine, 4,4'- diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 3, 3', 5,5'- tetramethyl-4,4'-diaminodicyclohexylmethane, 4,8-diamino-tricyclo[5.2.1 .0]decane, norbornanediamine, menthanediamine or menthenediamine;

- aromatic diamines such as tolylenediamine, xylylenediamine, in particular meta- xylylenediamine (MXDA), bis(4-aminophenyl)methane (MDA or methylenedianiline), or bis(4- aminophenyl)sulfone (also known as DADS, DDS or dapsone); - cyclic polyamines such as piperazine or N-aminoethylpiperazine;

- etheramines such as diaminodiglycol;

- polyetheramines, in particular difunctional and trifunctional primary polyetheramines based on polypropylene glycol, polyethylene glycol, polybutylene oxide, poly(butane-1 ,4-diol), polytetrahydrofuran (polyTHF) or polypentylene oxide, e.g. 4,7,10-trioxatridecane-1 ,3-diamine,

4.7.10-trioxatridecane-1 ,13-diamine, 1 ,8-diamino-3,6-dioxaoctane (XTJ-504, from Huntsman),

1.10-diamino-4,7-dioxadecane (XTJ-590, from Huntsman), 1 ,12-diamino-4,9-dioxadodecane (from BASF), 1 ,3-diamino-4,7,10-trioxatridecane (from BASF), primary polyetheramines based on polypropylene glycol and having an average molar mass of 230, such as Polyetheramine D 230 (from BASF) or Jeffamine® D 230 (from Huntsman), difunctional, primary polyetheramines based on polypropylene glycol and having an average molar mass of 400, such as Polyetheramine D 400 (from BASF) or Jeffamine XTJ 582 (from Huntsman), difunctional, primary polyetheramines based on polypropylene glycol and having an average molar mass of 2000, such as Polyetheramine D 2000 (from BASF), Jeffamine D 2000 or Jeffamine XTJ 578 (from Huntsman), difunctional, primary polyetheramines based on propylene oxide having an average molar mass of 4000, such as Polyetheramine D 4000 (from BASF), trifunctional, primary polyetheramines prepared by reacting propylene oxide with trimethylolpropane followed by amination of the terminal OH groups and having an average molar mass of 403, such as Polyetheramine T 403 (from BASF) or Jeffamine T 403 (from Huntsman), trifunctional, primary polyetheramines prepared by reacting propylene oxide with glycerol followed by amination of the terminal OH groups and having an average molar mass of 5000, such as Polyetheramine T 5000 (from BASF) or Jeffamine T 5000 (from Huntsman), aliphatic polyetheramines formed from a polyethylene glycol grafted with propylene oxide and having an average molar mass of 600, such as Jeffamine ED-600 or Jeffamine XTJ-501 (from Huntsman), aliphatic polyetheramines formed from a polyethylene glycol grafted with propylene oxide and having an average molar mass of 900, such as Jeffamine ED-900 (from Huntsman), aliphatic polyetheramines formed from a polyethylene glycol grafted with propylene oxide and having an average molar mass of 2000, such as Jeffamine ED-2003 (from Huntsman), difunctional, primary polyetheramines prepared by amination of a diethylene glycol grafted with propylene oxide and having an average molar mass of 220, such as Jeffamine HK-511 (from Huntsman), aliphatic polyetheramines based on a copolymer formed from poly(tetramethylene ether glycol) and polypropylene glycol and having an average molar mass of 1000, such as Jeffamine XTJ-542 (from Huntsman), aliphatic polyetheramines based on a copolymer formed from poly(tetramethylene ether glycol) and polypropylene glycol and having an average molar mass of 1900, such as Jeffamine XTJ-548 (from Huntsman), aliphatic polyetheramines based on a copolymer formed from poly(tetramethylene ether glycol) and polypropylene glycol and having an average molar mass of 1400, such as Jeffamine XTJ- 559 (from Huntsman), polyethertriamines based on an at least trihydric alcohol grafted with butylene oxide and having an average molar mass of 400, such as Jeffamine XTJ-566 (from Huntsman), aliphatic polyetheramines prepared by amination of alcohols grafted with butylene oxide and having an average molar mass of 219, such as Jeffamine XTJ-568 (from Huntsman), polyetheramines based on pentaerythritol and propylene oxide and having an average molar mass of 600, such as Jeffamine XTJ-616 (from Huntsman), polyetheramines based on triethylene glycol and having an average molar mass of 148, e.g. Jeffamine EDR- 148 (from Huntsman), difunctional, primary polyetheramines prepared by amination of an ethylene glycol grafted with propylene oxide and having an average molar mass of 176, such as Jeffamine EDR-176 (from Huntsman), and polyetheramines prepared by amination of polytetrahydrofuran (polyTHF) and having an average molar mass of 250, e.g. PolyTHF-Amine 350 (from BASF) and mixtures of said amines;

- polyamidoamines (amidopolyamines) obtainable by reacting dimeric fatty acids (e.g., linoleic acid dimer) with low-molecular-weight polyamines such as diethylenetriamine, 1-(3- aminopropyl)-3-aminopropane or triethylenetetramine or other diamines such as the aliphatic or cycloaliphatic diamines mentioned herein-before;

- adducts obtainable by reacting polyamines, in particular diamines, with a substoichiometric amount of epoxy resin or reactive diluent;

- urethane groups-containing adducts obtainable by reacting compounds with oxathiolanone groups and compounds with primary or secondary amino groups, wherein the amino groups are in stoichiometric excess compared to the oxathiolanone groups, thus giving a urethane groups-comprising adduct which still has primary or secondary amino groups, but essentially no oxathiolanone groups

- phenalkamines, such as those known from epoxide chemistry;

- Mannich bases, for example those prepared through condensation of polyamines, preferably diethylenetriamine, triethylenetetramine, isophoronediamine, 2,2,4- and 2,4,4- trimethylhexamethylenediamine, 1 ,3- and 1 ,4-bis(aminomethyl)cyclohexane with aldehydes, preferably formaldehyde, and monohydric or polyhydric phenols having at least one aldehydereactive ring position, e.g. the various cresols and xylenols, p-t-butylphenol, resorcinol, 4,4'- dihydroxydiphenylmethane, 4,4'-dihydroxy-2,2-diphenylpropane, but preferably phenol;

- amino acids, for example lysine or ornithine.

Preferred is a curable coating composition, wherein the compound B is a compound having at least two amino groups selected from a primary amino group, a secondary amino group and any combination thereof.

The primary and secondary amino groups are especially aliphatic or cycloaliphatic amino groups.

Also preferred is a curable coating composition, wherein the compound B is a compound having at least one primary amino group, preferably at least two primary amino groups.

Accordingly, in a preferred aspect, the invention relates to a waterborne coating composition containing a) the aqueous dispersion comprising a copolymer A1 , as defined in any aspect herein, b) a compound B having at least one primary amino group, preferably at least two primary amino groups, and c) optionally a compound C having at least two functional groups reactive towards a SH group.

Preferred compounds B are

- aliphatic polyamines, in particular 2, 2-dimethylpropylenediamine, - cycloaliphatic diamines, in particular 1 ,3-bis(aminomethyl))cyclohexane, isophoronediamine, N-cyclohexylpropylene-1 ,3-diamine and 4,4'-diaminodicyclohexylmethane (Dicykan);

- etheramine, in particular diaminodiglycol;

- difunctional or trifunctional primary polyetheramines based on polyethylene glycol or poly-THF;

- polyamines in which there is high mobility and low steric hindrance about the amino group, for example, a,w-diamino-n-alkanes, in which the alkyl chain may be interrupted by oxygen atoms (for example 4,9-dioxadodecane-1 ,12-diamine or 4,7,10-trioxatridecane-1 ,13-diamine, PolyTHF-Amine 350 (BASF)) or polyethyleneimine (for example Lupasol® FG).

A mixture of different compounds B may also be used, for example a small amount of a rapid curing compound B that establishes immediate strength without reducing the pot life of the product to be cured too much, plus a slow curing compound B for final curing. A suitable example may be a mixture of a compound B having at least one primary amino group with low steric hindrance and a compound B having at least one primary amino group with higher steric hindrance.

Various mixtures of the above-mentioned compounds B may be used, in particular a compound having two primary amino groups, selected from an aliphatic amino group or a cycloaliphatic amino group, in admixture with, for example above-mentioned polyetheramines.

The compound B may comprise further functional groups than a primary and/or a secondary amino group, preferably a group which may additionally contribute to cross-linking, for example a polymerizable ethylenically unsaturated group.

The compound B may comprise or may be a compound B1 that, in addition to the at least one amino group selected from a primary amino group, a secondary amino group and any combination thereof, still has at least one functional group reactive towards a SH group, selected from an ethylenically unsaturated group or CEC bond-containing group. Molecular weights and number of amino groups, including ethylenically unsaturated groups, are preferably as described for compound B. The compound B1 preferably has one, two or three primary or secondary amino groups, particularly preferably at least one or precisely one primary amino group. The compound B1 preferably has one, two or three ethylenically unsaturated groups or a CEC bond-containing group, more preferably one ethylenically unsaturated group, most preferably a vinyl or allyl group.

The compound B1 preferably contains no other functional groups aside from an ethylenically unsaturated group, a CEC bond-containing group, a primary or secondary amino group, a hydroxy group, a carboxylic ester group or an ether group. The compound B1 is particularly preferably a compound having only one primary amino group and only one ethylenically unsaturated group, especially a compound having only one primary amino group and only one ethylenically unsaturated group, selected from a vinyl group and an allyl group.

Examples of a suitable compound B1 include an aminoalkyl vinyl ether having 1 to 10 carbon atoms in the alkyl group (e.g., 3-aminopropyl vinyl ether), allylamine or diallylamine. A suitable example of a compound B1 with a CEC bond-containing group is propargyl amine.

Preferably, a compound B with one primary amino group is

- a monoalkyl amine such as Ci-C₂o-alkylamine;

- a cycloalkyl amine such as C₃-Ci₂-cycloalkyl amine;

- an etheramine such as 2-methoxyethylamine or 3-methoxypropylamine;

- a di- or polyetheramine such as di- or polyglycol amine or polyoxypropylene amine; or

- a compound B1 having one primary amino group and one vinyl or allyl group, such as 3- aminopropyl vinyl ether or allyl amine.

A preferred mixture of compounds B is a mixture of a compound B having at least two amino groups, selected from a primary amino group, a secondary amino group and a combination thereof, and a compound B having one amino group selected from a primary amino group, a secondary amino group and any combination thereof.

A more preferred mixture of compounds B is a mixture of a compound B having at least two amino groups, selected from a primary amino group, and a compound B having one amino group selected from a primary amine group.

In case of a mixture of a compound B having at least two amino groups, preferably a primary amino group, and a compound B having one amino group, preferably a primary amino group, including a compound B1 , the compound having only one amino group may be present in an amount of up to 30 wt%, based on the total weight of the compounds B, preferably up to 20 wt%.

In case a compound C is not present, compound B is preferably polyfunctional.

The compound B or a polyfunctional compound B may have two or more amino groups selected from a primary amino group, a secondary amino group and any combination thereof. Also, the compound B or a polyfunctional compound B may have at least one, especially one, amino group selected from a primary amino group, a secondary amino group and a combination thereof, and at least one, especially one, ethylenically unsaturated group or a CEC bondcontaining group.

Preferably, a polyfunctional compound B may have

- two or more amino groups selected from a primary amino group, a secondary amino group and any combination thereof, especially two or three primary amino groups; or

- one amino group, selected from a primary amino group and a secondary amino group, and one or two ethylenically unsaturated groups; especially one primary amino group and one vinyl group or allyl group.

Especially preferred is a curable coating composition, wherein a polyfunctional compound B having at least two, especially two or three, primary amino groups are present. Accordingly, a curable coating composition is more preferred, with the proviso that compound B is polyfunctional, when the first component does not comprise a compound C, wherein a polyfunctional compound B comprises a compound having two or more amino groups selected from a primary amino group, a secondary amino group and any combination thereof.

The curable coating composition may optionally comprise at least one compound C that has at least one functional group reactive towards a SH group. A curable coating composition is preferred, wherein compound C is present.

In a preferred aspect, the invention relates to a waterborne coating composition containing a) an aqueous dispersion, as defined in any aspect herein, b) a compound B having at least one primary amino group and/or a secondary amino group, said primary or secondary amino group may be present in a masked, latently reactive form, and c) a compound C having at least one functional group reactive towards a SH group.

Preferably, with the proviso that at least one compound of the compounds B and C is polyfunctional.

Preferably, the reaction of the functional group reactive towards a SH group with a SH group may be an addition reaction. A less preferred reaction is a condensation reaction, for example a reaction with a carbonyl group, or a nucleophilic substitution reaction, for example with an organic halide like an organic chloride.

A compound C undergoing an addition reaction may have at least one functional group reactive towards a group SH selected from an ethylenically unsaturated group, a CEC bond-containing group, an epoxy group and any combination thereof.

Preferably, the compound C has at least one functional group reactive towards a SH group selected from an ethylenically unsaturated group, an epoxy group and any combination thereof.

A particular preferred ethylenically unsaturated group is a (meth)acryloyl group, an allyl group or a vinyl group, especially a (meth)acryloyl group.

The compound C may have a molecular weight of up to 500,000 g/mol. In the case of polymers, this is the weight-average molecular weight, measured by gel-permeation chromatography using a polystyrene standard. The compound C preferably has a molecular weight of up to 1000 g/mol, particularly preferably from 60 g/mol to 500 g/mol.

It is possible for a compound C to have, for example, up to 1000, in particular up to 500, preferably up to 100, functional groups reactive towards a SH group. The compound C particularly preferably has two or three functional groups reactive towards a SH group. A CEC bond-containing group may react twice with SH groups. An SH group may first add to a CEC bond, converting the C=C bond into a C=C bond. The C=C bond formed may react with a further SH group. A C=C bond-containing group is therefore equivalent to two ethylenically unsaturated groups reactive towards a SH group.

Examples of a compound C containing a CEC bond-containing group are alkynes such as acetylene or propyne, propargyl alcohol, ethers of propargyl alcohol, esters of propargyl alcohol or amides of propargylamine.

Preferably, the compound C does not comprise a primary amino group or a secondary amino group.

The compound C may have one functional group reactive towards a SH group or two or more functional groups reactive towards a SH group, preferably one, 2 or 3 functional groups reactive towards a SH group, more preferably 2 or 3 functional groups towards a SH group.

Preferred functional groups towards a SH group, which is an ethylenically unsaturated group may be following groups:

A vinyl group CH₂=CH-; a vinylene group -CH=CH-; an acryloyl group CH₂=CH-C(=O)-; a methacryloyl group CH₂=C(CH₃)-C(=O)-; an acryloyloxy group CH₂=CH-C(=O)-O-; a methacryloyloxy group CH₂=C(CH₃)-C(=O)-O; an acrylamido group CH₂=CH-C(=O)-N; a cyanoacryl group CH₂=C(CN)-C(=O)-O; a methylenemalonato group CH₂=C[C(=O)-O]₂; a vinylene-1 ,3-dicarbonyl group CH₂=C[C(=O)-]₂; a 1 ,4-dicarboxyalkylene group -OC(=O)-CH =CH-C(=O)O-]; an allyl group CH₂=CH-CH₂-, in particular an allyl ether group CH₂=CH-CH₂-O-; a maleimido group or a crotonyl group.

Examples of a preferred compound C having one ethylenically unsaturated group include an acryloyl compound, a methacryloyl compound, a vinyl ester, for example vinyl acetate, a vinyl ether, or a vinyl lactam, for example N-vinylpyrrolidone.

A particularly preferred compound C having one ethylenically unsaturated group is a (meth)acryloyl compound and a vinyl ether. Examples of a (meth)acryloyl compound are (meth)acrylic esters, in particular alkyl or hydroxyalkyl (meth)acrylates, like glycerol- mono(meth)acrylate, or (meth)acrylonitrile. Vinyl ethers are, for example, vinyl alkyl ethers. Alkyl groups preferably have 1 to 20, particularly preferably 1 to 8, carbon atoms. Especially preferred examples of a compound C having one ethylenically unsaturated group include Ci-C₈-alkyl or hydroxy-Ci-C₈-alkyl (meth)acrylates, especially methacrylates, for example, glycerol- mono(meth)acrylate.

An especially preferred compound C is a compound having at least two (meth)acryloyl groups, a compound having at least two vinyl groups, an olefin having at least two C=C bonds, a polyester substituted with two or more ethylenically unsaturated groups, a cyanurate substituted with two or more ethylenically unsaturated groups or an isocyanurate substituted with two or more ethylenically unsaturated groups.

Preferred compounds C having at least two ethylenically unsaturated groups are:

- Olefins having two or more C=C bonds are, for example, butadiene, cyclooctadiene, cyclododecatriene, isoprene, limonene, divinylcyclohexane, trivinylcyclohexane, polybutadiene or polyisoprene;

- (Meth)acrylic esters of polyfunctional alcohols or of alkoxylated, especially ethoxylated or propoxylated, polyfunctional alcohols; examples of polyfunctional alcohols are bifunctional alcohols, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, neopentyl glycol, 1 ,7-heptanediol, 1 ,8-octanediol, 1 ,9-nonanediol, 1 ,10-decandiol, alkoxylated phenols, such as ethoxylated or propoxylated bisphenols, 1 ,2- or 1 ,4-cyclohexanedimethanol, isosorbide, tricyclodecanedimethanol, 2,2,4,4-tetramethyl-1 ,3-cyclobutanediol; trifunctional and higher functional alcohols are, for example, glycerol, trimethylolpropane, butanetriol, trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol and the corresponding alkoxylated, especially ethoxylated and/or propoxylated alcohols;

- (Meth)acrylic esters of polyesterols; suitable polyesterols are, for example, ones that can be prepared by esterifying polycarboxylic acids, preferably dicarboxylic acids, with polyols, preferably with diols; preferred dicarboxylic acids are succinic acid, glutaric acid, adipic acid, sebacic acid, and orthophthalic acid and the isomers and hydrogenation products thereof, and also the esterifiable or transesterifiable derivatives of said acids, for example the anhydrides and alkyl esters thereof; also suitable as dicarboxylic acids are maleic acid, fumaric acid, and tetrahydrophthalic acid or their anhydrides; preferred polyols are ethylene glycol, 1 ,2- and 1 ,3- propylene glycol, butane-1 ,4-diol, hexane-1 ,6-diol, neopentyl glycol, cyclohexanedimethanol, and polyglycols of ethylene glycol and/or propylene glycol;

- Epoxy (meth)acrylates, for example, those that can be prepared by reacting epoxidized olefins or poly-, mono- or diglycidyl ethers such as bisphenol A diglycidyl ether with (meth)acrylic acid;

- Urethane (meth)acrylates, such as the reaction products of hydroxyalkyl (meth)acrylates with poly- or diisocyanates;

- Unsaturated polyesters, in particular those containing C=C bonds from maleic acid, itaconic acid or fumaric acid units;

- Compounds having at least two vinyl or allyl groups, for example divinyl ethers such as diethylene glycol divinyl ether or triethylene glycol divinyl ether or divinyl sulfone; also suitable as compounds C having two or more ethylenically unsaturated groups are diallylorthophthalate, triallyl-isocyanurate or triallyl-cyanurate.

A compound C having at least two ethylenically unsaturated groups is more preferably a (meth)acrylic ester of a polyfunctional alcohol, a compound having a vinyl ether group or an unsaturated polyester.

Most preferred, a compound C having at least two ethylenically unsaturated groups include a (meth)acrylic ester, especially a methacrylic ester, of a polyfunctional alcohol or of an alkoxylated polyfunctional alcohol, for example, 1 , 1 ,1 -trimethylolpropane tri(meth)acrylate, ethoxylated 1 , 1 ,1 -trimethylolpropane tri(meth)acrylate, a C₂-C₈-alkanediol di(meth)acrylate, isosorbide di(meth)acrylate, and tricyclodecanedimethanol-di(meth)acrylate.

Preferred compounds C having at least two ethylenically unsaturated groups are in particular polyfunctional (meth)acrylic esters available under the names La romer® (BASF), Sartomer® (Arkema) or Miramer® (Miwon).

In a preferred embodiment, the compound C does not comprise other functional groups than a functional group reactive towards a SH group, a carboxylic ester group or an ether group.

Any mixture of one or more compounds C having at least one ethylenically unsaturated groups may also be used.

Preferred is a mixture of a compound C having at least two ethylenically unsaturated groups with a compound C having one ethylenically unsaturated group, wherein the amount of a compound C having one ethylenically unsaturated group may be in the range of up to 20 wt%, based on the total weight of compound C having at least two ethylenically unsaturated groups.

Also suitable as a compound C are those having at least one epoxy group, for example compounds obtainable by reacting compounds having at least one alcohol group with epichlorohydrin.

Compounds C having one epoxy group are, for example, epichlorohydrin or derivatives thereof in which the chloride of the epichlorohydrin is replaced by a hydroxy group (glycidol), by an ether group (glycidyl ether), by an ester group (glycidyl ester) or by an amino group (glycidyl amine).

Compounds C having at least two epoxy groups, are, for example, compounds obtainable by reacting compounds having at least two alcohol group with epichlorohydrin.

Examples of compound C having at least two epoxy groups are

- diglycidyl ethers of bisphenol A or of bisphenol F or of bisphenol S, the diglycidyl ethers of hydrogenated bisphenol A or of hydrogenated bisphenol F, and diglycidyl ethers of aliphatic diols, for example diglycidyl ethers of polyalkoxylene diols;

- oligoglycidyl ethers of oligoalcohols;

- epoxy resins obtainable by using compounds having at least two alcohol groups in excess with respect to epichlorohydrin; in epoxy resins of this kind, the degree of polymerization of the compound having at least two alcohol groups is preferably 2 to 25, in particular 2 to 10;

- epoxidized fatty acids, epoxidized fatty acid esters, and epoxidized fatty alcohols that in each case have at least two epoxy groups;

- tetraglycidyl methylenedianiline (TGMDA), triglycidyl p-aminophenol, and triglycidyl isocyanurate; - compounds obtainable by polymerization or copolymerization of glycidyl vinyl ether or of glycidyl (meth)acrylate, wherein a copolymer of glycidyl (meth)acrylate is different from a copolymer A1 and usually do not have an oxathiolanone group.

Any mixture of one or more compounds C having at least one epoxy groups may also be used.

Preferred is a mixture of a compound C having at least two epoxy groups with a compound C having one epoxy group, wherein the amount of a compound C having one epoxy group may be in the range of up to 20 wt%, based on the total weight of compound C having at least two epoxy groups.

Preference is also given to using a mixture of at least one compound C having at least one ethylenically unsaturated group and at least one compound C having at least one epoxy group.

Preference is also given to using a mixture of at least one compound C having at least two ethylenically unsaturated groups and at least one compound C having at least two epoxy groups. Especially preferred is a mixture of trimethylolpropane trimethacrylate and trimethylolpropane triglycidylether.

A compound C may have different functional groups reactive towards a SH group, for example at least two different ethylenically unsaturated groups, or one ethylenically unsaturated group and one epoxy group. Suitable examples of such compound C are vinyl (meth)acrylate, allyl (meth)acrylate, glycidyl (meth)acrylate or allyl glycidyl ether or polymeric compounds comprising different functional groups, wherein the polymeric compounds usually do not have an oxathiolanone group.

The compound C may comprise or may be a compound C1 that, in addition to the at least one functional group reactive towards a SH group, still has one oxathiolanone group. The compound C1 preferably has one functional group reactive towards a SH group and one oxathiolanone group. The functional group reactive towards a SH group may be an ethylenically unsaturated group, especially a (meth)acryloyl group, in particular a methacryloyl group.

A preferred compound C1 is a monomer M1 of formula (I), more preferably a monomer M1 of formula (Ila).

Any mixture of two or more compounds C may be used.

In case of a mixture of a compound C having at least two functional groups reactive towards a SH group and a compound C having one functional group reactive towards a SH group, including a compound C1 , the compound having only one functional amino group may be present in an amount of up to 30 wt%, based on the total weight of the compounds C, preferably up to 20 wt%. A polyfunctional compound C may have two or more functional groups reactive towards a SH group. Also, a polyfunctional compound C may have at least one, preferably one, functional group reactive towards a group SH and an oxathiolanone group.

Preferably, a polyfunctional compound C may have

- two or more functional groups reactive towards a SH group, especially two or three functional groups reactive towards a SH group, selected from a (meth)acryloyl group, an epoxy group and a combination thereof; or

- one functional group reactive towards a SH group and one oxathiolanone group, especially a meth(acryloyl) group and one oxathiolanone group.

Preferred is a curable coating composition containing a) an aqueous dispersion, as defined in any aspect herein, b) a compound B having at least one amino group, selected from a primary amino group, a secondary amino group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form, and c) optionally a compound C having at least one functional group reactive towards a SH group, with the proviso that at least one compound of the compounds B and C is polyfunctional, wherein a polyfunctional compound B comprises a compound having two or more amino groups selected from a primary amino group, a secondary amino group and any combination thereof, or a compound having at least one amino group selected from a primary amino group, a secondary amino group and any combination thereof, and having at least one group, selected from an ethylenically unsaturated group and a CEC bond-containing group; and a polyfunctional compound C comprises a compound having at least two functional groups reactive towards a SH group, or a compound having at least one functional group reactive towards a group SH and an oxathiolanone group.

More preferred is a curable coating composition, wherein the polyfunctional compound B comprises a compound having two or three primary amino groups; or a compound having one primary amino group and having one vinyl group or allyl group; or and the polyfunctional compound C comprises a compound having two or three functional groups reactive towards a SH group, selected from a (meth)acryloyl group or an epoxy group; or a compound having one (meth)acryloyl group and one oxathiolanone group.

A curable coating composition is preferred, wherein compound C is present.

Accordingly, in a preferred aspect, the invention relates to a waterborne coating composition, wherein the compound C is a compound having at least two functional groups reactive towards a SH group, selected from an ethylenically unsaturated group, an epoxy group and any combination thereof, preferably selected from a (meth)acryloyl group, an epoxy group and any combination thereof.

Especially preferred is a curable coating composition containing a) an aqueous dispersion, as defined in any aspect herein, b) a compound B having at least two primary amine groups, and c) a compound C having at least two functional groups reactive towards a SH group, selected from an ethylenically unsaturated group or an epoxy group, preferably selected from a (meth)acryloyl group or an epoxy group.

Within the process of curing the curable composition, the oxathiolanone group of copolymer A1 typically reacts with a compound B to form a mercaptourethane group resulting in the formation of a copolymer having urethane groups and -SH groups. Generally, primary amines react more rapidly than secondary amines, and aliphatic amines react more rapidly than aromatic amines. It is understood that a reaction with a secondary amine results in a N-substituted urethane group (a carbamate group).

The principles of the reaction of a compound with an oxathiolanone group (corresponding to copolymer A1), a compound B and optionally a compound C as well as details of the parameters of the reaction are described in WO 2019/034470 A1 and WO 2019/034473 A1.

Without or with sub-stoichiometric addition of a compound C, the -SH groups may oxidize and may form disulfide bridges. Such oxidation may occur at room temperature in the presence of oxygen. Such reaction may also occur in case SH groups remain after the reaction of compound C. Disulfide bridges may improve mechanical properties of the polymer obtained.

In case a compound C is present, the SH-groups react with the reactive groups of the compound C to obtain a cross-linked polymer. The obtained copolymer comprises as structural element a urethane group N(C=O)O with a sulfur atom bonded via an ethylene group to the oxygen of the urethane group. In case of a reaction with a compound B having a secondary amino group a substituted urethane group (carbamate group) is formed. This structural unit may be represented by the following general formula

(III).

Within the curable coating composition of copolymer A1 , compound B and optional compound

C, it is preferable to avoid a large excess of the copolymer A1 , respectively the amount of the monomer M1 , compound B or compound C. The copolymer A1 , compound B and compound C are generally used in an amount that deviates not more than 50% from the equimolar amounts corresponding to the stoichiometry of the reaction, preferably not more than 20%.

The number of functional groups, to be cured, in copolymer A1 , compound B, optional compound C and optional compounds like compound B1 and compound C1 , is preferably such that this results in the formation of cross-linked polymers.

The curable coating composition preferably comprises compound B in an amount such that the amount of primary and/or secondary amino groups in compound B is of from 50 to 150 mol%, preferably from 80 to 120 mol%, based on one mole of oxathiolanone groups present in the curable coating composition, with the proviso that only the amount of primary amino groups is considered in case of the compound B has primary and secondary amino groups.

The amount of secondary amino groups is considered in case the compound B does not have primary amino groups.

The term “one mole of oxathiolanone groups present in the curable coating composition” means all oxathiolanone groups present in the copolymer A1 and the optional compound C1.

In case the copolymer A1 may comprise an ethylenically unsaturated carboxylic acid, the amount of the compound B may be accordingly increased.

The curable coating composition preferably comprises compound C in an amount such that the amount of functional groups reactive towards a SH group of compound C is of from 0 to 120 mol%, more preferably from 50 to 120 mol%, most preferably from 90 to 110 mol%, based on one mole of oxathiolanone groups present in the curable coating composition.

The reaction between the aqueous dispersion comprising a copolymer A1 , compound B and compound C may be carried out in one step or two steps.

A one-step reaction means that the aqueous dispersion comprising a copolymer A1 and the compounds B and C are reacted simultaneously. The result of the one-step reaction depends on the nature of compound C, as reactive group(s) of compound C may also react with the amino group(s) of compound B thus reducing the availability amino groups for the ring-opening reaction of the oxathiolanone group.

A one-step reaction is preferably carried out with a compound C having at least one methacryloyl group as ethylenically unsaturated group or a compound C having at least one other ethylenically unsaturated group which is a non-activated double bond, such as a vinyl ether or an olefin. The addition of -SH to said non-activated double bond is preferably achieved via radical reaction which may be thermally catalyzed and/or photoinitiated. In a two-step reaction, the oxathiolanone groups undergo the ring opening reaction with the amino group(s) of the compound B separately in a first step, followed by the reaction of the formed -SH groups of the obtained polymer having urethane groups with the reactive group(s) of compound C.

Preferably, a compound C with at least one epoxy group as functional group is reacted with copolymer A1 and compound B following the two-step reaction by first reacting copolymer A1 with compound B and then reacting the SH-group and urethane group containing polymer with compound C.

In case of a one-step reaction the curable coating composition may be obtainable by mixing a) an aqueous dispersion comprising a copolymer A1 , as defined in any aspect herein, b) a compound B having at least one amino group, selected from a primary amine group, a secondary amine group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form, and c) optionally a compound C having at least one functional group reactive towards a SH group.

In case of a two-step reaction a curable coating composition may be obtainable by mixing the reaction product of a) an aqueous dispersion comprising a copolymer A1 , as defined in any aspect herein, and b) a compound B having at least one amino group, selected from a primary amine group, a secondary amine group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form, with c) a compound C having at least one functional group reactive towards a SH group.

The curable coating composition may be a curable one-component coating composition or a two-component coating composition, dependent on the final application.

A curable one-component coating composition may be obtained by blending the instant aqueous dispersion, the compound B and the optional compound C in a suitable mixer. Once the one-component coating composition is formulated, it is packaged in a suitable container.

The curable coating composition may be a curable two-component coating composition, wherein a first component contains a) the aqueous dispersion, as defined in any aspect herein, and c) optionally a compound C having at least one functional group reactive towards a SH group; and a second component contains b) a compound B having at least one amino group, selected from a primary amino group, a secondary amino group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form.

For example, for industrial coatings, the curable coating composition may be a curable two- component coating composition, wherein the aqueous dispersion comprising a copolymer A1 and the compound B may be held in separate components that are mixed only shortly before use. If present, compound C is usually already mixed with the aqueous dispersion comprising the copolymer A1 . The compound C may be added to the aqueous dispersion as such or suitably dissolved or dispersed in water, optionally in the presence of a suitable surfactant.

The compound B may be added to the aqueous dispersion comprising the copolymer A1 and optional component C either as it is and be dissolved or dispersed in said composition or in form of a pre-formed aqueous solution or dispersion, optionally in the presence of a suitable surfactant.

The waterborne coating compositions typically contain the aqueous polymer dispersion of the invention and thus contain the copolymer A1 resulting from the polymerization of the monomers M in the form of fine particles and also optionally the surfactants used in the emulsion polymerization, such as emulsifiers and/or protective colloids.

In addition to the constituents A, B and optionally C, the curable coating composition, may comprise at least one additive customary for this purpose, like catalysts, formulation auxiliaries, fillers and pigments. The choice of suitable additives for the curable coating composition generally depends on the particularly intended use and can be determined in the individual case by those skilled in the art.

The waterborne curable coating composition may comprise at least one catalyst. The curable coating composition preferably comprises at least one catalyst.

The curable composition may comprise

- at least one catalyst for catalyzing the reaction of the oxathiolanone groups, present in the curable composition, mainly of copolymer A1 and optionally of a compound C1 , with the primary and/or secondary amino groups, present in the curable composition, mainly in compound B including compound B1 , and/or

- at least one catalyst or initiator for catalyzing or initiating the reaction of SH groups with one another, and/or

- at least one catalyst or initiator for catalyzing the reaction of SH groups with the functional groups that are reactive therewith, for example, with an ethylenically unsaturated group or a CEC group-containing group.

Preferred is a curable coating composition, which comprises at least one catalyst for catalyzing the reaction of the oxathiolanone groups with primary and/or secondary amino groups.

In one embodiment, no catalyst is needed, particularly in the case of compound B that has amino groups as functional groups, i.e., the content of catalysts in the composition is then less than 0.01 wt%. A catalyst is preferably used when the compound B having primary and/or secondary amino groups having a higher steric hindrance, for example, polyetheramines based on polypropylene glycol. Suitable catalysts for catalyzing the reaction of the oxathiolanone groups with the primary and/or secondary amino groups are, for example, basic catalysts, preferably organic amines and organic phosphines. Preferred organic amines are amidines such as 1 ,8- diazabicyclo[5.4.0]undec-7-ene (DBU), 1 ,5-diazabicyclo[4.3.0]non-5-ene (DBN), guanidines such as 1 ,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) or 7-methyl-1 ,5,7-triazabicyclo[4.4.0]decene (mTBD), pyridines such as pyridine, and tertiary amines such as tri-Ci-C₆-alkylamines, in particular triethylamine. Preferred organic phosphines are trialkylphosphines and triarylphosphines, for example tri-n-butylphosphine and triphenylphosphine.

Preferably, the curable coating composition comprises a basic catalyst, selected from an organic amine, an organic phosphine and any combination thereof, especially from an organic amine selected from an amidine base, a pyridine, and a tertiary amine.

More preferably, the curable coating composition comprises a basic catalyst, selected from an organic amine, an organic phosphine and any combination thereof, especially from an organic amine selected from an amidine base, a pyridine, and a tri-Ci-C₆-alkylamine, wherein the basic catalyst is present in an amount of from 0.01 to about 10 wt%, based on the total weight of the compound B, preferably from 0.01 to 5 wt%.

Suitable catalysts or initiators for catalyzing or initiating the reaction of SH groups with one another are, for example, metal oxides, like MnO₂. If present, the catalyst or initiator for catalyzing or initiating the reaction of SH groups with one another is generally used in an amount of from 0.01 to about 10 wt%, based on the total weight of the Monomers M, preferably from 0.01 to 5 wt%.

Suitable catalysts or initiators for catalyzing or initiating the reaction of a SH group with an ethylenically unsaturated group or a CEC bond-containing group are compounds that form free radicals, e.g., azo initiators such as AIBN, organic peroxide compounds, redox pairs (H₂O₂, t- butyl peroxide, ascorbic acid) and also photoinitiators and oxygen itself. In the case of an activated double bond (so-called Michael systems), the reaction of the double bond can take place nucleophilically and can therefore be catalyzed, e.g., by tertiary amines, guanidines, pyridines, phosphines, etc.. In the case of a non-activated double bond, the reaction of the double bond can take place in a free-radical process and can be initiated thermally with a radical initiator or photochemically with a photoinitiator.

If present, the catalyst or initiator for catalyzing or initiating the reaction of a SH group with an ethylenically unsaturated group or a CEC bond-containing group is usually present in an amount of from 0.01 to about 10 wt%, based on the total weight of the compound C, preferably from 0.01 to 5 wt%.

The various kinds of catalysts may also be used in the form of any mixture.

Pigments used may in principle be any white or color pigments known in the art, for example, inorganic white pigments, like titanium dioxide, white organic pigments, like non-filming hollow polymer particles that are rich in styrene and carboxyl groups and have a particle size of about 300 to 400 nm (so-called opaque particles), colored inorganic pigments, colored organic pigments and mixtures thereof.

Examples of a filler include naturally occurring minerals, for example calcite, chalk, dolomite, kaolin, talc, mica, diatomaceous earth, baryte, quartz or talc/chlorite assemblages, and synthetically produced inorganic compounds, for example precipitated calcium carbonate, calcined kaolin or barium sulfate, and fumed silica. A preferred filler is calcium carbonate in the form of crystalline calcite or of amorphous chalk.

The proportion of the pigments and fillers in the waterborne coating compositions may be described in a manner known per se via the pigment volume concentration (PVC). The PVC describes the ratio of the volume of pigments (VP) and fillers (VF) relative to the total volume, consisting of the volumes of binder (VB), pigments (VP) and fillers (VF) in a dried coating film in percent: PVC = (VP + VF) x 100 / (VP + VF + VB). Generally, the PVC may vary and will not exceed a value of 80. In case of an exterior use coating the PVC may be in the range from 0 to 50.

The waterborne coating composition may contain typical formulation auxiliaries. The total amount of typical formulation auxiliaries is usually of from 0.1 to 30 wt%, in particular, from 0.5 to 10 wt%, based on the total weight of the waterborne coating composition. Examples of formulation auxiliaries include, but are not limited to pigment dispersants, wetting agents, rheology modifying agents, leveling agents, plasticizers, optical brigtheners, buffers, stabilizers like biocides, defoamers, antifreeze agents, flow promoters, film forming agents and filmforming auxiliaries, like organic solvents.

Examples of formulation auxiliaries are well known in the art and may be suitably selected dependent on the final application.

A film-forming auxiliary generally lowers the minimum film forming temperature (MFFT) of a polymer dispersion. The amount of a filming auxiliary is typically chosen, such that a MFFT in the range of 0 to 15°C results. The amount of a film-forming auxiliary may vary dependent on the final application, for example up to 20 wt%, based on the total weight of the monomers M.

The waterborne coating compositions typically comprise not more than 20 wt%, preferably not more than 10 wt%, based on the total weight of the waterborne curable coating composition, of a water-miscible organic solvent. The curable coating composition may also be solvent-free, apart from water, aside from typical antifreeze agents and film-forming auxiliaries. Solvent-free means that it contains less than 5 wt% of a water-miscible organic solvent, more preferably less than 2 wt% or none at all.

Preferably, a film-forming auxiliary is not required. The waterborne coating composition may be exclusively formulated on the basis of water, especially with a compound B and an optional compound C, which are preferably liquid and/or sufficiently water-soluble, so that an organic solvent may be dispensed.

Preferably, the amount of volatile organic matter, i.e., the content of organic compounds with boiling points up to 250°C under standard conditions (101 ,325 kPa) as determined by ISO 17895:2005 via gas-chromatography is less than 0.5 wt%, in particular less than 0.2 wt%, based on the total weight of the waterborne curable coating composition.

The amount of the aqueous polymer dispersion in the waterborne coating composition may vary depending on the desired purpose and the desired recipe of the coating composition in a known manner. In particular, the waterborne coating composition contains the polymer dispersion of the copolymer A1 in such an amount that the amount of the copolymer A1 in the waterborne coating composition is in the range of 5 to 60 wt%, based on the total amount of solids in the waterborne coating composition.

Preferred is a waterborne curable coating composition, containing a) an aqueous dispersion, as defined in any aspect herein, b) a compound B having at least one amino group, selected from a primary amino group, a secondary amino group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form, c) optionally a compound C having at least one functional group reactive towards a SH group, and d) at least one additive selected from a catalyst, a formulation auxiliary, a filler, a pigment and any combination thereof.

The additives may be added to one of the constituents of the curable coating composition or may be added after blending the constituents. In a two-component coating composition, the catalysts may be added either in the first or second component of the curable composition. For example, organic bases may preferably be added to the second component. Radical-forming catalysts may preferably be added in the first component.

The instant waterborne coating composition may be used for permanently coating a substrate.

Accordingly, in a further aspect, the invention relates to a process of producing a coating, the process comprising a) applying a waterborne curable coating composition, as defined in any aspect herein, to a substrate or surface, and b) allowing the waterborne curable coating composition to cross-link to form the coating.

The waterborne coating composition may be applied to surfaces and/or substrates to be coated in a customary manner, such as, for example, by applying the waterborne coating composition with brushes or rolls, by spraying, by dipping, by rolling, by curtain coating or by bar coating. The coating of surfaces and/or substrates is effected in such a way that the surface and/or substrate is first coated with a waterborne composition of the invention and then the wet coating is subjected to a curing step. The curing step is typically carried out at a temperature of from +5 to +80°C and in particular from +10 to +70°C. Typically, a temperature of +5 to +30°C will be sufficient to achieve an acceptable permanent coating. However, a higher temperature will accelerate the curing speed, and a temperature of up to +80°C or up to +70°C may also be suitable. Typically, curing is carried out at a relative humidity of from 30 to 90%.

The curing of the curable coating composition is preferably carried out at temperatures of < 70°C, preferably of < 50°C, more preferably < 30°C, especially without heating.

Principally, the waterborne coating composition may be applied to any substrate, which is conventionally coated by waterborne coating compositions. Examples of a substrate may be metal, coated metal, asphalt, concrete, plaster, fiber cement boards, stone, ceramic, minerals (mineral building materials), wood, paper, plastics, fiber-reinforced composites and glass.

The waterborne coating composition may be applied to interior or exterior surfaces, such as, for example, an architectural surface, such as a roof, a wall, a floor and a ceiling. The waterborne coating composition is also suitable for coating mineral substrates including stone walls and concrete surfaces such as shaped mineral articles including roof tiles and fiber cement boards.

The waterborne curable coating composition may be used for any kind of coating including a render. A render is a coating for interior or exterior walls, generally applied in a plurality of layers and with a larger layer thickness (several mm). The render is generally applied for smoothing or providing a more attractive appearance, and, in the case of exterior application, for protecting the surface from moisture.

The coating may be decorative or protective. An example of a protective coating may be an industrial coating, which may usually be used in interior or exterior applications.

A preferred application of the waterborne coating composition may be an exterior-use coating, like an architectural coating, for example due to the presence of thioether linkages.

Accordingly, in a further aspect, the invention relates to the use of a waterborne curable coating composition, as defined in any aspect herein, for preparing a coating on a substrate, preferably a decorative coating or a protective coating.

In a further aspect, the invention relates to a coating containing a cross-linked waterborne coating composition, as defined in any aspect herein, on a substrate, preferably a decorative or protective coating.

Preferably, the substrate is selected from metal, coated metal, asphalt, concrete, plaster, fiber cement board, stone, ceramic, mineral, wood, plastics, fiber-reinforced composites and glass.

Typically, the amount of waterborne coating composition is chosen such that the coating applied to the substrate, after curing (in dried form), has a layer thickness of < 2 mm or < 8 mm (for renders), advantageously > 0.01 mm and < 1.5 mm and especially advantageously > 0.05 mm and < 0.5 mm. Two or more identical or different coating layers may also be applied successively to a substrate.

The copolymer A1 is advantageous in that the copolymer in form of an aqueous dispersion may function as intermediate to form isocyanate-free urethane bonds. Thus, reduced toxicity may be achieved at least in part by the exclusion of isocyanates and/or isocyanate degradation or reaction products.

Further, the aqueous polymer dispersion allows to provide a coating based on water-insensitive polyurethane-forming moiety.

The copolymer A1 may be suitably used in form of an aqueous dispersion as a binder in waterborne coating and adhesive compositions. The aqueous dispersions may be easily processed on any kind of substrate. The aqueous dispersions allow for waterborne curable coating compositions showing good film-forming properties and providing coatings with high mechanical strength, hardness, elasticity, chemical resistance, corrosion resistance and low water-uptake.

Combined with the advantages of the class of poly(meth)acrylate a suitable copolymer A1 could be achieved with varying amount of oxathiolanone groups leading to a high cross-linking density when processing with polyfunctional amines B and compounds C. The waterborne curable coating compositions are advantageous in that the compositions are able to cross-link under various conditions with respect to temperature and relative humidity to form a crack-free film.

The waterborne coating compositions are also advantageous with respect to environmental aspects in that only a small amount of organic solvent, preferably no organic solvent is required. They me be easily formulated as one-component system.

The viscosity of the waterborne curable coating compositions, as described herein, do not strongly increase upon storage, i.e., said compositions are sufficiently storage stable.

The definitions and preferences given for the process mentioned herein-before apply in any combination as well as in any combination for the other aspects of the invention.

The present invention will now be explained in more detail with reference to the following examples. These examples should not be construed as limited. Unless otherwise stated, “%” is always % by weight (wt%).

Examples

The parameters were determined as follows:

Solids Content The solid content was determined by drying a defined amount of the aqueous polymer dispersion (about 2 g) to constant weight in an aluminum crucible having an internal diameter of about 5 cm at 130°C in a drying cabinet (2 hours). The ratio of the mass after drying to the mass before drying gave the solids content of the polymer dispersion. Two separate measurements were conducted. The value reported in the example is the mean of the two measurements. pH value pH values of the polymer dispersion were measured according to the standard method DIN EN 1262:2004-01.

Particle size analysis of polymer dispersion by HDC

The weight-average particle diameter of the polymer dispersions was determined by hydrodynamic chromatography fractionation (HDC). Measurements were carried out using a PL-PSDA particle size distribution analyzer (Polymer Laboratories, Inc.). A small amount of sample of the polymer dispersion of interest was injected into an aqueous eluent containing an emulsifier, resulting in a concentration of approximately 0.5 g/l. The mixture was pumped through a glass capillary tube of approximately 15 mm diameter packed with polystyrene spheres. As determined by their hydrodynamic diameter, smaller particles can sterically access regions of slower flow in capillaries, such that on average the smaller particles experience slower elution flow. The fractionation was finally monitored using an UV detector which measured the extinction at a fixed wavelength of 254 nm.

HDC mean is the weight-averaged mean-value of particle-size.

Viscosity

Viscosity was measured at 20°C according to the standard method DIN EN ISO 3219:1994 using a “Brookfield RV”-type laboratory viscosimeter employing spindles #4 or #5 at 60 revolutions per minute (rpm).

Coarse coaqulum formed during polymerization (> 125 urn)

After completion of the polymerization the obtained polymer dispersion was filtered through a nylon filter with a 125 pm mesh size, and the solid filter content was weighed. The weight of the filter content in relation to total mass of obtained wet polymer dispersion gave the proportion of coagulum in wt% (wet/wet).

Fine coaqulum determination (> 10 pm)

Measurement of the amount of fine coagulum in the dispersion was conducted similar to the measurement of the particle size analysis with the exception that the particle size distribution of the coarser particles (> 10 pm) was measured by the light scattering method (DLS). Production of coagulates with particle sizes above 10 pm is an indication of colloidal instability. All values are given in pg of coagulate particles per gram of dispersion.

Particle size analysis of polymer dispersion by DLS

The particle diameter of the polymer dispersion was determined by dynamic light scattering (DLS) of an aqueous polymer dispersion diluted with deionized water to 0.001 to 0.5 wt% (optically clear dispersion) at 22°C by means of a High Performance Particle Sizer (HPPS) from Malvern Instruments, England. What is reported is the cumulant Z average diameter calculated from the measured autocorrelation function (EN-ISO 22412:2017).

Gel content [%1 and swelling index

The polymer film was cut into at least two pieces with a surface area of around 1 cm² Each film piece was placed into a fared 100 mL flask, the weight of the polymer film was noted, and the flask was filled with methyl ethyl ketone (MEK) as organic solvent. The film was then stored for 24 hours under gently shaking. Afterwards, the content of the flask was poured over a 45 pm filter in order to isolate the swollen polymer film. After carefully removal of residual amounts of the organic solvent by the aid of a tissue, the weight of the swollen polymer film was immediately determined. The polymer film was subsequently placed in a fume hood to allow the evaporation of the organic solvent overnight, followed by post-drying at 60°C in an oven. After cooling to room temperature, the dried polymer film was weighted once again.

The gel content was calculated by (1) and the swelling index by (2):

Tensile strength

DIN 53504 S3A specimens were punched out of polymer films and subjected to a tensile test according to ISO 527-2 by the use of a Zwick Z050 as measurement device. Hereby, the tensile strength o (in MPa) is determined as a function of the strain. The clamping pressure was 2 bar and the test speed 200 mm/min. The test was performed at 23°C and 50% relative humidity.

Water uptake [%1

The polymer film was cut into at least two pieces with a surface area of around 4 cm². Each film piece was placed into a fared 100 mL flask, the weight of the polymer film was noted, and the flask was filled with water. The film was then stored for 72 hours under gently shaking.

Afterwards, water was removed, and the polymer film carefully dabbed with a tissue. The weight of the polymer film was immediately determined, followed by post-drying at 60°C in an oven. After cooling to room temperature, the dried polymer film was weighted once again.

The water uptake was calculated by (3):

Transmittance (%)

The transmittance was determined by a Hach DR6000 UV-VIS spectrophotometer with RFID technology (190 - 1100 nm).

Odor estimation: panel test The odor of the polymer films obtained in Examples 2 to 6 was tested after 4 weeks of curing.

The polymer films were tested at room temperature by 3 different people. The participants reported their olfactoral assessment according to the following classification scheme:

The odor was judged pursuant to a scale from 1 to 5. 1 : odorless

2: slight stale odor

3: slight “mercaptan odor”

4: “mercaptan odor”

5: distinct ’’mercaptan odor”

Synthesis Example 1

5-(methacryloyloxy)methyl-1 ,3-oxathiolane-2-one of formula (Ila) was prepared according to Example 8 of WO 2019/034469 A1 .

Example 1 a) Preparation of an aqueous dispersion

Feed A sodium peroxodisulfate (4 wt% aqueous solution) (81 .25 g)

Feed B deionized water (301 .73 g)

Disponil SDS 15 (15 wt% aqueous solution of sodium lauryl sulfate) (59.80 g) n-butyl acrylate (344.50 g) methyl methacrylate (273.00 g) monomer of formula (Ila) (32.50 g)

Feed B was prepared by mixing the ingredients.

A reaction vessel, equipped with a thermometer, nitrogen purge line, oil bath with temperature control, mechanical stirring device and raw material feed pumps, was charged with 227.50 g of deionized water and 5.20 g of Disponil SDS 15 (15 wt% solution) under nitrogen atmosphere, and the mixture was preheated under stirring (150 rpm) to 90°C internal temperature. After reaching this temperature 20 wt% of feed A were added within 2 min, and the mixture was stirred for 10 min, followed by adding remaining feed A and feed B simultaneously within 3 hours and stirring for further 60 min, while maintaining the temperature of 90°C. Afterwards, the mixture was cooled to room temperature, 27.30 g of triethylamine (10 wt% in water) were added slowly under stirring and filtered to remove any formed coagulants. A dispersion with a solids content of about 50 wt% and having a pH value of 7.5 was obtained.

Content of course coagulum < 0.1 wt% b) Preparation of a polymer film (as test specimen)

A silicon mold with the dimension 14.7 cm x 6.6 cm was used in which 35 ml of a polymer dispersion, diluted from the polymer dispersion obtained in Example 1a), having a 20 wt% solids content were filled.

A polymer film with a thickness of approximately 700 pm was obtained after curing for 28 days in a climatic cabinet (23°C, 50% humidity).

General procedure of Examples 2 to 5

35 ml of a polymer dispersion, diluted from the polymer dispersion obtained in Example 1 a) to a 20 wt% solids content, were mixed with an amine (compound B) and optionally a (meth)acrylate compound (compound C) (added equimolar based on functionality) and stirred for at least 30 min. The resultant mixture was filled in a silicon mold with the dimension 14.7 cm x 6.6 cm. A polymer film with a thickness of approximately 700 pm was obtained after curing for 28 days in a climatic cabinet (23°C, 50% humidity).

Example 2

35 ml of a polymer dispersion of Example 1a), diluted to a 20 wt% solids content 190 mg of 4,7,10-trioxa-1 ,13-tridecanediamine

Example 3

35 ml of a polymer dispersion of Example 1a), diluted to a 20 wt% solids content

108 mg of 1 ,3-bis(aminomethyl)-cyclohexane

Example 4

190 mg of 4,7,10-trioxa-1 ,13-tridecanediamine

195 mg of trimethylolpropane-trimethacrylate

Example 5

190 mg of 4,7,10-trioxa-1 ,13-tridecanediamine

288 mg of tricyclodecane-dimethanol-dimethacrylate

With respect to the storage stability, the parameters were measured immediately after mixing the components (“fresh”) to form a formulation and after storage of said formulation for 14 days at 50°C in an oven.

The results of the parameters determined are shown in Tables 1 and 2.

Table 1

The values for the water uptake are low (the variance of ± 2% is neglectable).

Table 2: Storage stability

The change of the values of transmittance, viscosity, fine coagulum is considered to be neglectable. Thus, the results demonstrated that essentially no coagulate forming occurs and the aqueous dispersions are storage stable.

Odor estimation

All films obtained were odorless (scale 1) after 4 weeks of curing.

Claims

1. An aqueous dispersion comprising a polymeric compound A having at least one unit derived from a monomer having a group of formula

2. The aqueous dispersion according to claim 1 , wherein the polymeric compound A is a copolymer A1 , obtainable by a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula

(II), wherein

R¹ is H or methyl, preferably methyl,

X is Ci-C₄-alkylene, preferably methylene or ethylene, and at least one monoethylenically unsaturated monomer M2, wherein the amount of the monomer M1 of formula (I) is at most 30 wt%, based on the total weight of the monomers.

3. The aqueous dispersion according to claim 2, wherein the at least one monoethylenically unsaturated monomer M2 is selected from an ethylenically unsaturated carboxylic acid or a salt thereof, an ethylenically unsaturated amide, an ethylenically unsaturated nitrile, an ethylenically unsaturated carboxylic ester, a vinyl aromatic compound, a vinyl heteroaromatic compound, a vinyl ester, a vinyl ether, an allyl ether, a vinyl halide and any combination thereof, preferably selected from an ethylenically unsaturated carboxylic acid or salt thereof, an ethylenically unsaturated carboxylic ester, a vinyl aromatic compound and any combination thereof.

4. The aqueous dispersion according to claim 2 or 3, wherein the amount of the monomer M1 of formula (II) is of from 0.3 to 10 wt%, based on the total weight of the monomers, preferably 0.5 to 8 wt%.

5. The aqueous dispersion according to any of claims 2 to 4, wherein the mixture of ethylenically unsaturated monomers M contains:

(i) 0.3 to 10 wt%, based on the total weight of monomers M, of monomer M1 of formula (II); and at least one monoethylenically unsaturated monomer M2, containing

(ii) 90 to 99.7 wt%, based on the total weight of monomers M, of at least one monomer M2a, selected from a Ci-C₂2-alkylester of (meth)acrylic acid, a C₅-Ci₂-cycloalkylester of (meth)acrylic acid, a vinyl aromatic compound and any combination thereof; (iii) 0 to 5 wt%, based on the total weight of monomers M, of at least one monomer M2b, selected from an ethylenically unsaturated carboxylic acid; and

6. The aqueous dispersion according to any one of claims 2 to 5, wherein the monomer M2a contains at least 90 wt%, based on the total weight of monomers M, of a combination of (ii-1) at least one monomer M2a-1 , selected from styrene, Ci-C₄-alkyl esters of methacrylic acid, C₅-Ci2-cycloalkyl esters of methacrylic acid and any combination thereof; preferably selected from methyl methacrylate, styrene and a combination thereof; and

(ii-2) at least one monomer M2a-2 selected from C₂-Ci₂-alkyl esters of acrylic acid, preferably selected from n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate and any combination thereof.

7. A process of preparing an aqueous dispersion, as defined in any one of claims 1 to 6, the process comprising a free-radical aqueous emulsion polymerization of a mixture of monoethylenically unsaturated monomers M, containing a monomer M1 of formula

(II), as defined in claim 2, and at least one monoethylenically unsaturated monomer M2, as defined in any one of claims 3 to 6, wherein the emulsion polymerization is carried out in the presence of a free-radical initiator and preferably an emulsifier.

8. The use of an aqueous dispersion, as defined in any of claims 1 to 7, as a cross-linking agent or as a constituent in a curable waterborne coating or adhesive composition.

9. A waterborne curable coating composition, containing a) an aqueous dispersion, as defined in any one of claims 1 to 6, b) a compound B having at least one amino group, selected from a primary amino group, a secondary amino group and any combination thereof, said primary or secondary amino group may be present in a masked, latently reactive form, and c) optionally a compound C having at least one functional group reactive towards a SH group.

10. The waterborne curable coating composition according to claim 9, with the proviso that

- the compound B is polyfunctional, in case the compound C is not present, or

11 . The waterborne curable coating composition according to claim 9 or 10, wherein the compound B is a compound having at least one primary amino group, preferably at least two primary amino groups.

12. The waterborne curable coating composition according to any one of the claims 9, 10 or 11 , wherein the compound C is a compound having at least two functional group reactive towards a SH group, selected from an ethylenically unsaturated group, an epoxy group and any combination thereof, preferably selected from a (meth)acryloyl group, an epoxy group and any combination thereof.

13. The use of a waterborne curable coating composition, as defined in any one of claims 9 to 12, for preparing a coating on a substrate, preferably a decorative or a protective coating.

14. A coating containing a cross-linked waterborne coating composition, as defined in any of claims 9 to 12, on a substrate, preferably a decorative or a protective coating.

15. A process of producing a coating, the process comprising a) applying a waterborne curable coating composition, as defined in any one of claims 9 to 12, to a substrate, and b) allowing the waterborne curable coating composition to cross-link to form the coating.