Polymer binder based on 2-octyl acrylate, n-butyl acrylate and methyl methacrylate for aqueous coating compositions containing titanium dioxide

Abstract

This invention provides an aqueous polymer latex, which can be obtained by polymerizing a monomer composition M via free radical emulsion polymerization in the presence of a seed latex, wherein the monomer composition M comprises, by weight: a) 0.5 to 30 wt% 2-octyl acrylate, b) 25 to 55 wt% n-butyl acrylate, c) 35 to 65 wt% methyl methacrylate, d) 0 to 5 wt% one or more monoalkenyl unsaturated carboxylic acids, e) 0 to 5 wt% one or more monoalkenyl unsaturated carboxylamines, and f) 0 to 10 wt% one or more other alkene-unsaturated nonionic monomers different from monomers a), b), c), d), and e).

Description

Technical Field

[0001] This invention relates to an aqueous polymer latex, which can be obtained by polymerizing a monomer composition M comprising 2-octyl acrylate, n-butyl acrylate, and methyl methacrylate. The invention further relates to the use of the aqueous polymer latex as an adhesive in an aqueous coating composition containing titanium dioxide pigment, and also relates to an aqueous coating composition containing the aqueous polymer latex and titanium dioxide pigment. Prior Technology

[0002] Titanium dioxide (TiO2) is often used as a pigment in water-based coating compositions, such as latex paint. In addition to whiteness, TiO2 provides opacity or hiding power to the coating, meaning that the coating is opaque and covers the surface underneath or the substrate surface.

[0003] WO2017 / 191167 discloses an aqueous polymer latex used as a binder in water-based coating compositions containing titanium dioxide pigments. The aqueous polymer latex is obtained by polymerizing a monomer composition M via free radical emulsion polymerization using a specific feeding method, wherein the monomer composition M comprises the following: a) Based on the total weight of monomer composition M, 80 to 99.95% by weight of an olefinic unsaturated monomer M1, which is selected from a mixture of: at least one monomer M1a, selected from C1-C20-alkyl esters of acrylic acid and C5-C20-alkyl esters of methacrylic acid; and at least one monomer M1b, selected from vinyl aromatic monomers and C1-C4-alkyl esters of methacrylic acid; b) Based on the total weight of monomer composition M, 0.05 to 5% by weight of one or more monoolefin unsaturated monomers M2, which are selected from monoolefin unsaturated monocarboxylic acids having 3 to 6 carbon atoms and monoolefin unsaturated dicarboxylic acids having 4 to 6 carbon atoms; c) 0 to 20% by weight of nonionic monomer M3, which is different from monomer M1.

[0004] Preferred monomer M1a is a C2-C10 alkyl ester of acrylic acid, particularly ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, and 2-propylheptyl acrylate. Preferred monomer M1b is a vinyl aromatic monomer and a mixture of vinyl aromatic monomers and C1-C4 alkyl esters of methacrylic acid. In particular, monomer M1b is selected from styrene and mixtures of styrene and methyl methacrylate. Preferred monomer M2 is acrylic acid and methacrylic acid. Preferred monomer M3 is a hydroxy-C2-C4 alkyl ester of acrylic acid and methacrylic acid.

[0005] WO2014 / 207389 A1 relates to the use of polymers derived from the polymerization of 2-octyl acrylate from renewable sources and, where appropriate, at least one other monomer as a coating composition or as an adhesive for manufacturing coating compositions. The other monomer is preferably selected from esters of olefinic unsaturated monocarboxylic acids and dicarboxylic acids, especially methyl methacrylate and n-butyl acrylate; vinyl aromatic monomers, more particularly styrene; and mixtures thereof. This document discloses transparent coatings.

[0006] WO 2016 / 128574 relates to an aqueous polymer emulsion comprising at least 30 wt.% of a vinyl copolymer (A), the vinyl copolymer comprising: (I) 10 to 90 wt.% of 2-octyl acrylate monomer; (II) 10 to 90 wt.% of at least one itaconate ester monomer; and (III) 0 to 80 wt.% of olefinic unsaturated monomers other than (I) and (II).

[0007] Other olefinic unsaturated monomers (III) include acrylic acid and / or methacrylic acid and monomers selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate, styrene and combinations thereof.

[0008] WO2018 / 007325 A1 discloses an aqueous emulsion comprising at least 30 wt.% of a vinyl copolymer (A), which contains the following monomers: (I) Isomethacrylic acid The total amount of isobornyl methacrylate and 2-octyl acrylate is at least 30 wt.%, and isomethacrylate iso... The weight ratio of the ester to 2-octyl acrylate is 5:95 to 95:5; (II) Not exceeding 70 wt.% of at least one of the following, excluding 2-octyl acrylate and isomethacrylate. Alkene unsaturated monomers other than esters. Other alkene unsaturated monomers (II) include acrylic acid and / or Methacrylic acid and monomers selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate, styrene, and combinations thereof. This document discloses transparent coatings. Summary of the Invention

[0009] The objective of this invention is to provide alternative methyl methacrylate (MMA) copolymers having glass transition temperatures comparable to those of copolymers based on methyl methacrylate and n-butyl acrylate (BA), which are suitable for use as adhesives in TiO2-containing architectural coatings and exhibit good scrub resistance, thickening efficiency, gloss and opacity, as well as good adhesion, stain resistance and low dirt pick-up properties. []

[0010] This objective is achieved through an aqueous polymer latex, which can be obtained by polymerizing a monomer composition M via free radical emulsion polymerization, wherein, based on the total weight of the monomer composition M, the monomer composition M comprises: a) 0.5 to 30% by weight of 2-octyl acrylate, b) 25 to 55% by weight of n-butyl acrylate, c) 35 to 65% by weight of methyl methacrylate [, , ] d) 0 to 5% by weight of one or more mono-olefinic unsaturated carboxylic acids, e) 0 to 5% by weight of one or more monoene-based unsaturated carboxylic acids, f) 0 to 10% by weight of one or more other olefinic unsaturated nonionic monomers different from monomers a), b), c), d), and e).

[0011] It has been unexpectedly discovered that, compared to copolymers based on n-butyl acrylate and methyl methacrylate in reasonably formulated architectural coatings, the copolymers of the present invention based on 2-octyl acrylate, n-butyl acrylate (BA), and methyl methacrylate (MMA) produce improved scrub resistance, improved gloss, and improved thickening efficiency, as well as comparable opacity, tack, stain resistance, and detergency. Simple Explanation of the Diagram

[0012] none Implementation

[0013] Preferably, 2-octyl acrylate, n-butyl acrylate, and methyl methacrylate constitute at least 95% by weight of the monomer composition M. For example, 2-octyl acrylate may be present in an amount of 1 to 15% by weight of the monomer mixture M, n-butyl acrylate may be present in an amount of 25 to 55% by weight of the monomer mixture M, and methyl methacrylate may be present in an amount of 40 to 65% by weight of the monomer mixture M.

[0014] Preferably, the monoolefinic unsaturated carboxylic acid d) is selected from the group consisting of: acrylic acid, methacrylic acid, maleic acid, half-methyl ester of maleic acid, half-ethyl ester of maleic acid, citraconic acid, half-methyl ester of citraconic acid, itaconic acid, half-methyl ester of itaconic acid, 3-pentenoic acid, 2-butenoic acid, fumaric acid, half-methyl ester of fumaric acid, half-ethyl ester of fumaric acid, halogenated acrylic acid, and halogenated methacrylic acid. Most preferably, the monomer d) is selected from acrylic acid, methacrylic acid, and itaconic acid.

[0015] Preferably, the monoolefinic unsaturated carboxylic acid amide (e) is selected from the group consisting of: acrylamide, methacrylamide, N-methacrylamide, N-ethylacrylamide, N-propylacrylamide, N-isopropylacrylamide, N-butylacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, N-isopropylmethacrylamide, and N-butylmethacrylamide. Most preferably, the monomer (e) is selected from acrylamide and methacrylamide.

[0016] In a preferred embodiment, monomer d) is present in an amount of 0.1 to 4% by weight. In a more preferred embodiment, monomer d) is present in an amount of 0.5 to 3% by weight, or even more preferably 0.5 to 2% by weight, based on the total weight of the monomer composition.

[0017] In other preferred embodiments, monomer e) is present in an amount of 0.1 to 4% by weight. In even more preferred embodiments, monomer e) is present in an amount of 0.5 to 3% by weight, or even more preferably 1 to 3% by weight, based on the total weight of the monomer composition.

[0018] If monomer f) is present, it is preferably selected from the group consisting of: C2-C10 alkyl esters of acrylic acid, especially tert-butyl acrylate, 2-propylheptyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate; C1-C4 alkyl esters of methacrylate other than methyl methacrylate, especially 2-ethylhexyl methacrylate, butyl methacrylate, and tert-butyl methacrylate; and vinyl aromatic monomers, especially styrene.

[0019] In other preferred embodiments, monomer f) is not present in monomer composition M.

[0020] In a preferred embodiment, the monomer composition M comprises or is composed of the following: a) 1 to 15% by weight, preferably 3 to 12% by weight, of 2-octyl acrylate. b) 25 to 55% by weight, preferably 30 to 50% by weight, of n-butyl acrylate. c) 40 to 65% by weight, preferably 40 to 60% by weight, of methyl methacrylate. d) 0 to 5% by weight of one or more mono-olefinic unsaturated carboxylic acids, e) 0 to 5% by weight of one or more mono-ene unsaturated carboxylamines.

[0021] In a more specific example, the monomer composition M comprises or is composed of the following: a) 1 to 15% by weight, preferably 3 to 12% by weight, of 2-octyl acrylate. b) 25 to 55% by weight, preferably 30 to 50% by weight, of n-butyl acrylate. c) 40 to 65% by weight, preferably 40 to 60% by weight, of methyl methacrylate. d) 0 to 5% by weight of one or more mono-olefinic unsaturated carboxylic acids, selected from acrylic acid, methacrylic acid, and itaconic acid. e) 0 to 5% by weight of one or more mono-olefinic unsaturated carboxylic acids, selected from acrylamide and methacrylamide.

[0022] In a particularly preferred embodiment, the monomer composition M comprises the following: a) 3 to 12% by weight of 2-octyl acrylate, b) 30 to 50% by weight of n-butyl acrylate, c) 40 to 60% by weight of methyl methacrylate, d) 0 to 5% by weight of acrylic acid, e) 0 to 5% by weight of acrylamide.

[0023] In some preferred embodiments, the monomer composition M comprises the following: a) 3 to 12% by weight of 2-octyl acrylate, b) 30 to 50% by weight of n-butyl acrylate, c) 40 to 60% by weight of methyl methacrylate, d) 0.1 to 4% by weight of mono-olefinic unsaturated carboxylic acids selected from acrylic acid, methacrylic acid, and itaconic acid. e) 0.1 to 4% by weight of a mono-olefinic unsaturated carboxylic acid amide, selected from acrylamide and methacrylamide.

[0024] In some preferred embodiments, the monomer composition M comprises the following: a) 3 to 12% by weight of 2-octyl acrylate, b) 30 to 50% by weight of n-butyl acrylate, c) 40 to 60% by weight of methyl methacrylate, d) 0.5 to 3% by weight of acrylic acid, e) 0.5 to 3% by weight of acrylamide.

[0025] In some preferred embodiments, at least a portion of component a) of 2-octyl acrylate is derived from renewable feedstocks; that is, at least a portion of component a) of 2-octyl acrylate is bio-based 2-octyl acrylate obtained at least partially or entirely from renewable feedstocks. A mixture of 2-octyl acrylate obtained from fossil feedstocks and 2-octyl acrylate obtained partially or entirely from renewable feedstocks may also be used.

[0026] 2-Octyl acrylate can be synthesized, for example, by esterification of acrylic acid with 2-octanol or by transesterification of methyl acrylate or ethyl acrylate with 2-octanol.

[0027] Preferably, the bio-based 2-octyl acrylate is obtained by reacting 2-octanol with acrylic acid. Thus, 2-octanol and / or acrylic acid and / or methyl acrylate and / or ethyl acrylate are at least partially generated from renewable raw materials.

[0028] Bio-based 2-octanol derived from renewable raw materials can be obtained from castor oil.

[0029] Acrylic acid from renewable raw materials can be prepared, for example, according to WO 2006 / 092272 or DE 10 2006 039 203 A or EP 2 922 580.

[0030] According to the mass balance approach, at least a portion of the precipitates used to synthesize monomer composition M may also originate from renewable feedstocks. Accordingly, in addition to fossil feedstocks, renewable feedstocks such as bio-naphtha (as described, for example, in EP 2 290 045 A1 or EP 2 290 034 A1) also enter chemical production systems, such as steam crackers. The renewable feedstocks are converted into products along the chemical value chain, such as acrylic acid, butyl acrylate, methyl methacrylate, or acrylamide. The renewable material content of these products is defined by the mass balance approach and can be allocated to these products.

[0031] The method used to prepare the polymer latex is based on a well-known method of free radical emulsion polymerization. The conditions required for the efficient free radical emulsion polymerization of monomer M are sufficiently familiar to those skilled in this technique, for example, according to the prior art cited at the beginning and according to "Emulsions-polymerization" [Emulsion Polymerization] in Encyclopedia of Polymer Science and Engineering, Vol. 8, pp. 659 and onwards (1987); DC Blackley in High Polymer Latices, Vol. 1, pp. 35 and onwards (1966); H. Warson, The Applications of Synthetic Resin Emulsions, Chapter 5, pp. 246 and onwards (1972); D. Diederich, Chemie in unserer Zeit 24, pp. 135-142 (1990); Emulsion Polymerization, Interscience Publishers, New York (1965); DE-A 40 03 422 and Dispersionen synthetischer Hochpolymere [Dispersions of Synthetic High Polymers], F. Holscher, Springer-Verlag, Berlin (1969).

[0032] Free radical-initiated aqueous emulsion polymerization is triggered by free radical polymerization initiators (free radical initiators). These are, in principle, peroxide, azo compound, and redox initiator systems. Peroxides can be inorganic or organic peroxides.

[0033] In certain specific instances, inorganic peroxides are selected from the group consisting of: hydrogen peroxide and persulfates, such as monoalkali metal salts or dialkali metal salts or ammonium salts of persulfate, for example, monosodium salts and disodium salts, monopotassium salts and dipotassium salts or ammonium salts.

[0034] In other specific examples, organic peroxides are selected from the group consisting of: alkyl hydroperoxides, such as tert-butyl hydroperoxide, p-menthyl hydroperoxide, or cumene hydroperoxide; and dialkyl or diaryl peroxides, such as tert-butyl hydroperoxide or cumene hydroperoxide.

[0035] In other specific examples, the azo compounds are selected from the group consisting of 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylpentanitrile), and 2,2'-azobis(formamidinylpropyl) dihydrochloride.

[0036] In preferred embodiments, the free radical initiator is an inorganic peroxide, particularly a persulfate, and a redox initiator system.

[0037] The oxidants suitable for redox initiator systems are basically the peroxides specified above. Corresponding reducing agents that can be used are sulfur compounds with low oxidation states, such as alkali metal sulfites, for example, potassium sulfite and / or sodium sulfite; alkali metal bisulfites, for example, potassium bisulfite and / or sodium bisulfite; alkali metal metabisulfites, for example, potassium metabisulfite and / or sodium metabisulfite; formaldehyde sulfoxides, for example, potassium formaldehyde sulfoxide and / or sodium formaldehyde sulfoxide; alkali metal salts, especially potassium and / or sodium salts of aliphatic sulfinic acids and alkali metal hydrogen sulfide, for example, potassium hydrogen sulfide and / or sodium hydrogen sulfide; salts of polyvalent metals, such as ferric sulfate (II), ferric sulfate (II) ammonium, ferric phosphate (II); ethylene glycols, such as dihydroxymaleic acid, benzoin and / or ascorbic acid; and reducing sugars, such as sorbitol, glucose, fructose and / or dihydroxyacetone.

[0038] In a specific instance, the amount of free radical initiator used for emulsion polymerization M is initially fully loaded into the polymerization vessel. However, it is also possible to load no free radical initiator or only a portion thereof, for example, no more than 40% by weight, and especially no more than 30% by weight, of the total amount of free radical initiator required in the aqueous polymerization medium, and then, under polymerization conditions, during the free radical emulsion polymerization of monomer M, depending on the consumption, it is possible to add the entire amount or any remaining residue in batches, either in one or more portions or continuously at constant or varying flow rates.

[0039] In another preferred embodiment, the free radical aqueous emulsion polymerization of the present invention is carried out at a temperature ranging from 0 to 170°C, more preferably from 50 to 120°C, and most preferably from 60 to 120°C, and particularly at a temperature ranging from 70 to 110°C. The free radical aqueous emulsion polymerization can be carried out at a pressure less than, equal to, or greater than 1 atm.

[0040] In certain specific instances, polymerization is carried out in the presence of a chain transfer agent. The chain transfer agent is selected from the group consisting of: aliphatic and / or aryliphatic halogen compounds, such as n-butyl chloride, n-butyl bromide, n-butyl iodide, dichloromethane, vinyl dichloride, chloroform, bromoform, chloroform, dibromodichloromethane, carbon tetrachloride, carbon tetrabromide, benzyl chloride, benzyl bromide; organothioides, such as primary, secondary, or tertiary aliphatic thiols, such as 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 its isomers, n-octanethiol and its isomers, n-nonanethiol and its isomers, n-decanethiol and its isomers, n-undecanethiol and its isomers, n-dodecanethiol and its isomers, n-tridecanethiol and its isomers; substituted thiols, such as 2-hydroxyethylthiol; aromatic thiols, such as thiophene, o-, m-, or p-methylthiophene; alkyl esters of mercaptoacetic acid (thioglycolic acid), such as 2-ethylhexyl hydrothioacetate; alkyl esters of mercaptopropionic acid, such as octyl mercaptopropionate; and other sulfur compounds, described in Polymer. Handbook, 3rd edition, 1989, J. Brandrup and EH Immergut, John Wiley & Sons, Part II, pp. 133-141; and aliphatic and / or aromatic aldehydes, such as acetaldehyde, propionaldehyde and / or benzaldehyde; unsaturated fatty acids, such as oleic acid; dienes having non-conjugated double bonds, such as divinylmethane or vinylcyclohexane; or hydrocarbons having abstractable hydrogen atoms, such as toluene.

[0041] Generally speaking, the total amount of chain transfer agent (if present) shall not exceed 1 wt% based on the total amount of monomer M.

[0042] Generally, polymerization occurs in the presence of surfactants. Surfactants can be selected from emulsifiers and protective colloids. Protective colloids, in contrast to emulsifiers, are understood to be polymeric compounds with a molecular weight higher than 2000 Daltons, while emulsifiers typically have lower molecular weights. Surfactants can be anionic, nonionic, or a mixture of nonionic and anionic surfactants.

[0043] Anionic surfactants typically contain at least one anionic group, selected from phosphate, phosphonate, sulfate, and sulfonate groups. Anionic surfactants containing at least one anionic group are typically used in the form of their alkali metal salts, especially their sodium salts, or in the form of their ammonium salts.

[0044] In a preferred embodiment, the anionic surfactant is an anionic emulsifier, particularly one having at least one sulfate or sulfonate group. Similarly, an anionic emulsifier having at least one phosphate or phosphonate group can be used as the sole anionic emulsifier or in combination with one or more anionic emulsifiers having at least one sulfate or sulfonate group.

[0045] Examples of anionic emulsifiers containing at least one sulfate or sulfonate group include, for example, alkyl sulfate esters, especially salts of C8-C22-alkyl sulfate esters, particularly alkali metal salts and ammonium salts; monosulfate esters of ethoxylated alkanols, especially monosulfate esters of ethoxylated C8-C22-alkanols, preferably salts having an ethoxylation content (EO content) in the range of 2 to 40, particularly alkali metal salts and ammonium salts; monosulfate esters of ethoxylated alkylphenols, especially salts of monosulfate ethoxylated C4-C18-alkylphenols (EO content preferably 3 to 40), particularly alkali metal salts and ammonium salts; alkyl sulfonic acids, especially salts of C8-C22-alkyl sulfonic acids, particularly alkali metal salts and ammonium salts; dialkyl esters, especially salts of di-C1-C18-alkyl esters of sulfosuccinic acid, particularly alkali metal salts and ammonium salts; alkylbenzene sulfonic acids, especially C4-C... Salts of 22-alkylbenzenesulfonic acids, especially alkali metal salts and ammonium salts; and mono- or di-sulfonated, alkyl-substituted diphenyl ethers, such as salts of bis(benzenesulfonic acid) ethers with C4-C24-alkyl groups on one or both aromatic rings, especially alkali metal salts and ammonium salts. Examples are US-A 4,269,749 and Dowfax® 2A1 (Dow Chemical Company).

[0046] In a particularly preferred embodiment, the anionic surfactant is anionic emulsifier selected from the following group: • Alkyl sulfates, especially salts of C8-C22-alkyl sulfates, particularly alkali metal salts and ammonium salts. • Ethoxylated monoesters of alkanols, especially ethoxylated C8-C22-alkanols, preferably salts with an ethoxylation content (EO content) in the range of 2 to 40, particularly alkali metal salts. • Alkylbenzene sulfonic acids, especially ethoxylated alkylphenol sulfate monoesters of C4-C22-alkylbenzene sulfonic acids, especially ethoxylated C4-C18-alkylphenol sulfate monoesters (preferably with an EO content of 3 to 40), and • Monosulfonated or disulfonated, alkyl-substituted diphenyl ethers, such as bis(benzenesulfonic acid) ethers with C4-C24-alkyl groups on one or both aromatic rings.

[0047] Examples of anionic emulsifiers containing phosphate or phosphonate groups include, but are not limited to, the following salts, which are selected from the following group: • Monoalkyl phosphates and dialkyl phosphates, especially salts of C8-C22-alkyl phosphates, particularly alkali metal salts and ammonium salts, • Salts of the following, especially alkali metal salts and ammonium salts: phosphate monoesters of C2-C3-alkoxylated alkanols, preferably having an alkoxylation content in the range of 2 to 40, particularly in the range of 3 to 30, for example, phosphate monoesters of ethoxylated C8-C22-alkanols, preferably having an ethoxylation content (EO content) in the range of 2 to 40; phosphate monoesters of propoxylated C8-C22-alkanols, preferably having a propoxylation content (PO content) in the range of 2 to 40; and phosphate monoesters of ethoxylated-co-propoxylated C8-C22-alkanols, preferably having an ethoxylation content (EO content) in the range of 1 to 20 and a propoxylation content in the range of 1 to 20. • Salts of ethoxylated alkylphenol phosphate monoesters, especially ethoxylated C4-C18-alkylphenol phosphate monoesters (preferably with an EO content of 3 to 40), particularly alkali metal salts and ammonium salts. Alkylphosphonic acids, especially salts of C8-C22-alkylphosphonic acids, particularly alkali metal salts and ammonium salts, and • Alkylphenylphosphonic acids, especially salts of C4-C22-alkylphenylphosphonic acids, particularly alkali metal salts and ammonium salts.

[0048] Other suitable anionic surfactants can be found in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Vol. XIV / 1, Makromolekulare Stoffe [Macromolecular Substances], Georg-Thieme-Verlag, Stuttgart, 1961, pp. 192-208.

[0049] In other preferred embodiments, the surfactant comprises at least one anionic emulsifier having at least one sulfate or sulfonate group. The at least one anionic emulsifier having at least one sulfate or sulfonate group may be the only type of anionic emulsifier. However, a mixture of at least one anionic emulsifier having at least one sulfate or sulfonate group and at least one anionic emulsifier having at least one phosphate or phosphonate group may also be used. In such mixtures, the amount of the at least one anionic emulsifier having at least one sulfate or sulfonate group is preferably at least 50% by weight, based on the total weight of the anionic surfactants used in the method of the present invention. In particular, the amount of the anionic emulsifier having at least one phosphate or phosphonate group does not exceed 20% by weight, based on the total weight of the anionic surfactants used in the method of the present invention.

[0050] In other preferred embodiments, the surfactant may also comprise one or more nonionic surfactants, particularly selected from nonionic emulsifiers. Suitable nonionic emulsifiers are, for example, aryl or aliphatic nonionic emulsifiers, such as ethoxylated monoalkylphenols, dialkylphenols, and trialkylphenols (EO content 3 to 50, alkyl chain: C4-C10), ethoxylated derivatives of long-chain alcohols (EO content: 3 to 100, alkyl chain: C8-C36), and polyethylene oxide / polypropylene oxide homopolymers and copolymers. These emulsifiers may comprise epoxy alkyl units copolymerized randomly or in block form. A highly suitable example is an EO / PO block copolymer. Preferably, the surfactant is an ethoxylated long-chain alkyl alcohol (alkyl chain C1-C30, average ethoxylation content 5 to 100), and particularly preferably, those having C12-C20 alkyl chains and an average ethoxylation content of 5 to 20, and also ethoxylated monoalkylphenols. Preferably, based on the total amount of surfactant used in the method of the present invention, the surfactant used in the method of the present invention comprises less than 60% by weight, and particularly not more than 50% by weight, of nonionic surfactant.

[0051] In other specific examples, the surfactant used in the method of the present invention comprises at least one anionic surfactant and at least one nonionic surfactant, wherein the ratio of the anionic surfactant to the nonionic surfactant is typically in the range of 0.5:1 to 10:1, particularly 1:1 to 5:1.

[0052] In other preferred embodiments, one or more surfactants will be used in an amount of one or more surfactants in the range of 0.2% to 5% by weight, particularly in the range of 0.5% to 3% by weight, based on the amount of monomer M polymerized.

[0053] The aqueous reaction medium in the polymerization may also generally contain a small amount (≤ 5% by weight) of water-soluble organic solvents, such as methanol, ethanol, isopropanol, butanol, pentanol, and acetone. However, preferably, the method of the present invention is carried out in the absence of such solvents.

[0054] Generally, in each case, the obtained aqueous polymer dispersion has a polymer solids content in the range of 10% to 70% by weight, more preferably 20% to 65% by weight, more preferably 30% to 60% by weight, and most preferably 40% to 60% by weight, based on the total weight of the aqueous polymer dispersion.

[0055] It has been found advantageous to carry out free radical emulsion polymerization in the presence of a seed latex. The seed latex is a polymer latex present in the aqueous polymerization medium prior to the start of metering monomer M. The seed latex helps to better control the particle size of the final polymer latex obtained in the free radical emulsion polymerization of this invention.

[0056] Generally, each polymer latex can serve as a seed latex. For the purposes of this invention, a seed latex is preferred, wherein the polymer particles have a relatively small particle size. The Z-average particle size of the polymer particles in the seed latex is preferably in the range of 10 to 80 nm, particularly 10 to 50 nm, as determined by dynamic light scattering at 20°C. Preferably, the polymer particles of the seed latex are composed of olefinic unsaturated monomers, which, by weight of the total monomers forming the seed latex, comprise at least 95% by weight of one or more monomers selected from C2-C10 alkyl esters of acrylic acid, particularly ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, C1-C4 alkyl esters of methacrylate, particularly methyl methacrylate, and vinyl aromatic monomers, particularly styrene.

[0057] Therefore, the seed latex is typically loaded into the polymerization vessel before monomer M is metered. Specifically, the seed latex is loaded into the polymerization vessel, polymerization conditions are established, and at least a portion of the free radical initiator is loaded into the polymerization vessel before monomer M is metered.

[0058] The amount of seed latex in solid form, based on the total weight of the monomers Ma), b), c), and d), to be polymerized, can often range from 0.1% to 10% by weight, especially from 0.5% to 5% by weight.

[0059] This invention also relates to a water-based coating composition comprising: i) at least one aqueous polymer latex as defined above; and ii) Titanium dioxide pigment.

[0060] This invention also relates to the use of waterborne polymer latex as an adhesive in waterborne coating compositions containing titanium dioxide pigments.

[0061] The TiO2 concentration of the aqueous TiO2 pigment slurry or paste used to prepare the aqueous dispersion of the polymer composite is generally in the range of 30% to 85% by weight, often 40% to 80% by weight, and in each case, is based on the total weight of the aqueous TiO2 pigment slurry or paste. Titanium dioxide pigments used to prepare the aqueous dispersion of the polymer composite can be conventionally used in coating compositions, especially any TiO2 pigment in aqueous coating compositions. Typically, TiO2 pigments are used, wherein the TiO2 particles are preferably in rutile form. In another preferred embodiment, the TiO2 particles can also be coated, for example, with aluminum, silicon, and zirconium compounds.

[0062] Generally, the weight ratio of polymer to titanium dioxide pigment is in the range of ≥ 0.1:5.0 to ≤ 5.0:0.1; preferably, the weight ratio of polymer to titanium dioxide pigment is in the range of ≥ 0.5:5.0 to ≤ 5.0:0.5; more preferably, the weight ratio of polymer to titanium dioxide pigment is in the range of ≥ 0.5:3.0 to ≤ 3.0:0.5, and especially in the range of ≥ 0.5:1.5 to ≤ 1.5:0.5.

[0063] Preferably, the titanium dioxide pigment has an average initial particle size in the range of ≥ 0.1 µm to ≤ 0.5 µm, as determined by light scattering or electron microscopy.

[0064] Generally, waterborne coating compositions further comprise at least one additive selected from the group consisting of: thickeners, defoamers, leveling agents, film-forming aids, biocides, wetting agents or dispersants, fillers, and agglomerators.

[0065] The waterborne coating composition can be simply prepared by mixing TiO2 pigment powder or an aqueous slurry or paste of TiO2 pigment with the waterborne polymer latex of the present invention, preferably by applying shear stress to the mixture, for example, using a solvent conventionally used for preparing water-based paints. It is also possible to prepare an aqueous slurry or paste of TiO2 pigment and the waterborne polymer latex of the present invention, which is subsequently incorporated into other polymer latexes of the present invention, or mixed with other polymer latexes of the present invention or with any other polymer latex adhesive.

[0066] Aqueous dispersions of polymeric composites can also be prepared by incorporating the aqueous polymeric latex of the present invention as a binder or co-binder into an aqueous base formulation of paint containing TiO2 pigment, for example by mixing the aqueous polymeric latex of the present invention with a pigment formulation containing other additives conventionally used in paint formulations.

[0067] To stabilize TiO2 pigment particles in aqueous pigment slurries or pastes, mixing may be carried out, as appropriate, in the presence of additives (such as dispersants) known for use in aqueous pigment slurries or pastes. Suitable dispersants include, but are not limited to, polyphosphates such as sodium polyphosphate, potassium polyphosphate, or ammonium polyphosphate; alkali metal salts and ammonium salts of acrylic homopolymers or copolymers or maleic anhydride polymers; polyphosphonates such as sodium 1-hydroxyethane-1,1-bisphosphonate; and naphthalene sulfonates, especially their sodium salts.

[0068] In all cases, the polymer concentration in the aqueous polymer latex used to prepare the aqueous dispersion of the polymer composite is generally in the range of 10% to 70% by weight, preferably 20% to 65% by weight, and most preferably 30% to 60% by weight, based on the total weight of the aqueous polymer latex.

[0069] In addition to the polymer latex and titanium dioxide pigment of the present invention and conventional binders selected as appropriate, the waterborne coating composition may contain one or more pigments different from TiO2 pigments and / or fillers.

[0070] Suitable pigments for TiO2 pigments include, for example, inorganic white pigments such as barium sulfate, zinc oxide, zinc sulfide, basic lead carbonate, antimony trioxide, and lithopone (zinc sulfide + barium sulfate); or colored pigments such as iron oxide, carbon black, graphite, zinc yellow, zinc green, ultramarine, manganese black, antimony black, manganese violet, Prussian blue, or Paris green. In addition to inorganic pigments, the emulsion paint of this invention may also contain organic colored pigments, such as sepia, gamboge, Cassel brown, toluidine red, para red, Hansa yellow, indigo, azo dyes, anthraquinones, and indigo dyes, as well as bismuth subsalicylate. Quinacridone pigments, phthalocyanine pigments, isoindolinone pigments, and metal complex pigments are all suitable for enhancing light scattering. Synthetic white pigments with air inclusions are also suitable for enhancing light scattering, such as Ropaque® and AQACell® dispersions. Additionally, Luconyl® brand pigments from BASF SE, such as Luconyl® Yellow, Luconyl® Brown, and Luconyl® Red, especially transparent forms, are also suitable.

[0071] Preferred fillers are selected from the group consisting of: aluminum silicates, such as feldspar; silicates, such as kaolin, talc, mica, and magnesite; alkaline earth metal carbonates, such as calcium carbonate in the form of calcite or chalk, magnesium carbonate, and dolomite; and alkaline earth metal sulfates, such as calcium sulfate and silica. In the coating compositions of this invention, finely ground fillers are preferably natural. Fillers can be used as individual components. However, in practice, filler mixtures have been found to be particularly suitable, such as calcium carbonate / kaolin or calcium carbonate / talc. Glossy paints generally contain only a small amount of very finely ground filler, or no filler at all. Fillers also include matting agents that, if desired, significantly reduce gloss. Matting agents are generally transparent and can be organic or inorganic. Examples of matting agents are inorganic silicates, such as the Syloid® brand from WR Grace and the Acematt® brand from Evonik. Organic matting agents are available, for example, from the Ceraflour® and Ceramat® brands under BYK-Chemie, and from the Deuteron MK® brand under Deuteron.

[0072] Pigment volume concentration (PVC) can be used to describe the proportions of pigments and fillers in a coating composition in a manner known per se. PVC describes the ratio of pigment volume (VP) and filler volume (VF) to the total volume, which is composed of the binder volume (VB), pigment volume (VP), and filler volume (VF) in the dehydrated coating film as a percentage. PVC = (VP + VF) x 100 / (VP + VF + VB).

[0073] Preferably, the pigment volume concentration (PVC) of the coating composition of the present invention is ≤ 35%.

[0074] In another preferred embodiment, the wetting agent is selected from the group consisting of: sodium polyphosphate, potassium polyphosphate or ammonium polyphosphate; alkali metal salts and ammonium salts of acrylic acid copolymers or maleic anhydride copolymers; polyphosphonates, such as sodium 1-hydroxyethane-1,1-bisphosphonate; and naphthalene sulfonate, especially its sodium salt.

[0075] Suitable film-forming aids include, for example, Texanol or Optifilm from Eastman Chemicals, as well as glycol ethers and esters, such as Solvenon and Lusolvan from BASF SE and Dowanol from Dow. The amount of film-forming aid is preferably less than 10% by weight and more preferably less than 5% by weight of the entire formulation.

[0076] Suitable thickeners are, for example, associative thickeners, such as polyurethane thickeners. The amount of thickener is generally less than 5% by weight and more preferably less than 3% by weight of the entire formulation.

[0077] Other formulation components used in water-based paints are described in detail in M. Schwartz and R. Baumstark, "Water-based Acrylates for Decorative Coatings", Curt R. Vincentz Verlag, Hanover, 2001, pp. 191-212 (ISBN 3-87870-726-6).

[0078] The coating composition can be applied to the substrate using conventional methods, such as brushing, spraying, dipping, rolling, or rod coating.

[0079] In this case, the coating of the substrate is achieved by first coating the substrate with the aqueous coating formulation of the present invention and then subjecting the aqueous coating to a dehydration step, particularly in a temperature range from -10°C to 50°C, advantageously from 5°C to 40°C, and particularly advantageously from 10°C to 35°C.

[0080] The present invention will be further illustrated by the following embodiments. Example

[0081] The following components are used in embodiments of the present invention: Common Names / IUPAC Names Business Name Available for purchase Methyl methacrylate Methyl methacrylate BASF SE 2-Octyl Acrylate 2-Octyl Acrylate BASF SE n-Butyl acrylate n-Butyl acrylate BASF SE acrylic acid acrylic acid BASE SE Acrylamide Acrylamide BASF SE Polystyrene seed dispersion Polystyrene seed dispersion BASF SE Alkyl diphenyl oxide disulfonate Dowfax® 2A1 Dow Chemicals C 13H 27O(CH 2CH 2O)xH Lutensol® TO 82 BASF SE Sodium persulfate Sodium persulfate Sigma Aldrich Hydroperoxide tert-butyl Hydroperoxide tert-butyl BASF SE Sodium hydroxymethanesulfinate Rongalit® C Brueggemann Titanium dioxide Kronos 4311 Kronos Worldwide Neutralizing agent containing 2-amino-2-methyl-1-propanol AMP-95 Angus Chemical Company Ammonium salts of hydrophobic copolymers as dispersants Tamol 165 A Dow Hyperbranched polymer defoamer Foamstar 2420 BASF SE Non-volatile, nonionic surfactants used as surface leveling agents and wetting agents. Hydropalat WE 3320 BASF SE Nonionic associative thickeners Aquaflow® NHS-310 Ashland Polymer pigments Ropaque Ultra E Dow Filler produced from nepheline syenite Minex 10 Sibelco Cohesive 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate Texanol Eastman Low-odor coalescing agent Optifilm 400 Eastman biocides Proxel AQ Lonza fungicides Polyphase 663 Troy Company Nonionic associative thickeners Rheolate CVS 10 Elementis Nonionic associative thickeners Acrysol RM 895 Dow Attapulgite clay Attagel 50 BASF SE Example E1 Adhesives based on polymers containing 2-octyl acrylate, n-butyl acrylate, and methyl methacrylate

[0082] A reactor equipped with a stir bar, temperature controller, nitrogen inlet, and several injection possibilities was filled with 244.3 g of deionized water and 27.3 g of polystyrene seed dispersion (33 wt%, particle size: 30 nm). The reaction mixture was purged with nitrogen and heated to 85°C. 5.0 g of feed 2 was added at 85°C. After 5 minutes, feed 1 and feed 2 were added over 180 minutes. Feed 1: 400.5 g deionized water, 18.5 g Dowfax 2A1, 20.8 g Lutensol TO 82, 6.9 g acrylic acid, 13.9 g acrylamide (50 wt% aqueous solution), 34.8 g 2-octyl acrylate, 349.0 g methyl methacrylate, and 300.0 g n-butyl acrylate. Feed 2: 19.8 g aqueous sodium persulfate solution (7 wt%). The reaction mixture was post-polymerized at 85°C for 30 minutes. Feed 3 and Feed 4 were then added over 60 minutes. Feed 3: 6.9 g of aqueous tert-butyl hydroperoxide solution (10 wt%). Feed 4: 6.2 g of aqueous Rongalit C solution (10 wt%). The reaction mixture was then cooled to ambient temperature and neutralized with sodium hydroxide to pH 8-9. Tg (dehydrated dispersion): 21℃ Average particle size: 133 nm Solid content: 48.7 wt% Example E2 Adhesives based on polymers containing 2-octyl acrylate, n-butyl acrylate, and methyl methacrylate

[0083] A reactor equipped with a stir bar, temperature controller, nitrogen inlet, and several injection options was filled with 244.3 g of deionized water and 27.3 g of polystyrene seed dispersion (33 wt%, particle size: 30 nm). The reaction mixture was purged with nitrogen and heated to 85°C. 5.0 g of feed 2 was added at 85°C. After 5 minutes, feed 1 and feed 2 were added over 180 minutes. Feed 1: 400.5 g deionized water, 18.5 g Dowfax 2A1, 20.8 g Lutensol TO 82, 6.9 g acrylic acid, 13.9 g acrylamide (50 wt% aqueous solution), 69.5 g 2-octyl acrylate, 349.0 g methyl methacrylate, and 265.0 g n-butyl acrylate. Feed 2: 19.8 g aqueous sodium persulfate solution (7 wt%). The reaction mixture was post-polymerized at 85°C for 30 minutes. Feed 3 and Feed 4 were then added over 60 minutes. Feed 3: 6.9 g of aqueous tert-butyl hydroperoxide solution (10 wt%). Feed 4: 6.2 g of aqueous Rongalit C solution (10 wt%). The reaction mixture was then cooled to ambient temperature and neutralized with sodium hydroxide to pH 8-9. Tg (dehydrated dispersion): 17℃ Average particle size: 132 nm Solid content: 48.0 wt% Comparative Example C1 Adhesives based on polymers containing n-butyl acrylate and methyl methacrylate

[0084] A reactor equipped with a stir bar, temperature controller, nitrogen inlet, and several injection options was filled with 244.3 g of deionized water and 27.3 g of polystyrene seed dispersion (33 wt%, particle size: 30 nm). The reaction mixture was purged with nitrogen and heated to 85°C. 5.0 g of feed 2 was added at 85°C. After 5 minutes, feed 1 and feed 2 were added over 180 minutes. Feed 1: 400.5 g deionized water, 18.5 g Dowfax 2A1, 20.8 g Lutensol TO 82, 6.9 g acrylic acid, 13.9 g acrylamide (50 wt% aqueous solution), 349.0 g methyl methacrylate, and 335.0 g n-butyl acrylate. Feed 2: 19.8 g aqueous sodium persulfate solution (7 wt%). The reaction mixture was post-polymerized at 85°C for 30 minutes. Feed 3 and feed 4 were then added over 60 minutes. Feed 3: 6.9 g aqueous tert-butyl hydroperoxide solution (10 wt%). Feed 4: 6.2 g aqueous Rongalit C solution (10 wt%). The reaction mixture was then cooled to ambient temperature and neutralized with sodium hydroxide to pH 8-9. Tg (dehydrated dispersion): 19℃ Average particle size: 132 nm Solid content: 48.1 wt% Example E3 Formula of semi-gloss varnish containing adhesive from Example E1

[0085] 315.0 g of Kronos 4311 pigment was mixed with 15.0 g of water. Under low stirring speed, 1.75 g of AMP-95 neutralizer (Angus Chemical), 5.0 g of propylene glycol (Univar), 2.0 g of Foamstar 2420 defoamer (BASF), 10.0 g of Tamol 165 A dispersant (Dow), and 3.0 g of Hydropalat WE 3320 wetting agent (BASF) were added. Under high stirring speed, 1.5 g of Attagel 50 (BASF), 25.0 g of Minex 10 (Sibelco) filler, and 20.0 g of Aquaflow NHS-310 (Ashland) nonionic associative thickener were added and mixed for 30 minutes. Subsequently, 105.8 g of deionized water was added, and the mixture was filtered through a 400 µm filter. Then add 496.8 g of the binder from Example E1, 25.0 g of Ropaque Ultra E polymeric pigment (Dow), 2.0 g of Foamstar 2420 defoamer (BASF), 9.0 g of Texanol coalescing agent (Eastman), and 7.5 g of Optifilm 400 coalescing agent (Eastman) and mix for 5 minutes. Next, add 2.0 g of Proxel AQ biocidal agent (Lonza), 3.0 g of Polyphase 663 fungicide (Troy), and 2.0 g of Rheolate CVS 10 nonionic associative thickener (Elementis) and mix for 5 minutes. Finally, add 2.0 g of Acrysol RM 895 nonionic associative thickener (Dow) and 3.5 g of water, and stir the mixture at medium speed for 30 minutes. Example E4 Formula of semi-gloss varnish containing adhesive from Example E2

[0086] 315.0 g of Kronos 4311 pigment was mixed with 15.0 g of water. Under low stirring speed, 1.75 g of AMP-95 neutralizer (Angus Chemical), 5.0 g of propylene glycol (Univar), 2.0 g of Foamstar 2420 defoamer (BASF), 10.0 g of Tamol 165 A dispersant (Dow), and 3.0 g of Hydropalat WE 3320 wetting agent (BASF) were added. Under high stirring speed, 1.5 g of Attagel 50 (BASF), 25.0 g of Minex 10 (Sibelco) filler, and 20.0 g of Aquaflow NHS-310 (Ashland) nonionic associative thickener were added and mixed for 30 minutes. Subsequently, 96.3 g of deionized water was added, and the mixture was filtered through a 400 µm filter. Then add 504.0 g of the binder from Example E2, 25.0 g of Ropaque Ultra E polymeric pigment (Dow), 2.0 g of Foamstar 2420 defoamer (BASF), 9.0 g of Texanol coalescing agent (Eastman), and 6.0 g of Optifilm 400 coalescing agent (Eastman) and mix for 5 minutes. Next, add 2.0 g of Proxel AQ biocidal agent (Lonza), 3.0 g of Polyphase 663 fungicide (Troy), and 2.0 g of Rheolate CVS 10 nonionic associative thickener (Elementis) and mix for 5 minutes. Finally, add 2.0 g of Acrysol RM 895 nonionic associative thickener (Dow) and 5.1 g of water, and stir the mixture at medium speed for 30 minutes. Comparative Example C2 Formulation of a semi-gloss varnish containing the adhesive from Example C1

[0087] Mix 315.0 g of Kronos 4311 pigment with 15.0 g of water. Add 1.75 g of AMP-95 neutralizer (Angus Chemical), 5.0 g of propylene glycol (Univar), 2.0 g of Foamstar 2420 defoamer (BASF), 10.0 g of Tamol 165 A dispersant (Dow), and 3.0 g of Hydropalat WE 3320 wetting agent (BASF) at low stirring speed. Add 1.5 g of Attagel 50 (BASF), 25.0 g of Minex 10 (Sibelco) filler, and 20.0 g of Aquaflow NHS-310 (Ashland) nonionic associative thickener at high stirring speed and mix for 30 minutes. Then, add 100.0 g of deionized water and filter the mixture through a 400 µm filter. Then add 503.0 g of the binder from Example C1, 25.0 g of Ropaque Ultra E polymeric pigment (Dow), 2.0 g of Foamstar 2420 defoamer (BASF), 9.0 g of Texanol coalescing agent (Eastman), and 5.0 g of Optifilm 400 coalescing agent (Eastman) and mix for 5 minutes. Next, add 2.0 g of Proxel AQ biocidal agent (Lonza), 3.0 g of Polyphase 663 fungicide (Troy), and 3.2 g of Rheolate CVS 10 nonionic associative thickener (Elementis) and mix for 5 minutes. Finally, add 1.5 g of Acrysol RM 895 nonionic associative thickener (Dow) and 5.4 g of water and stir the mixture at medium speed for 30 minutes.

[0088] Scrub resistance as measured according to ASTM D2486: Number of scrubbing cycles from the E3 coating before failure: 1411 Number of scrubbing cycles on the E4 coating before failure: 1247 Number of scrubbing cycles from C2 paint prior to failure: 1158

[0089] The scrub resistance of Examples E3 and E4 is significantly improved compared to Example C2. Gloss measurement:

[0090] Coatings were prepared using a 3-mil drawdown stick on Leneta 3B black and white sealable stencils. The films were dehydrated at room temperature for 24 hours. Gloss was measured using a gloss meter. The results are as follows: The gloss (20°) of the coating in Example E3 was 8.4. The gloss (20°) of the coating in Example E4 was 8.4. The gloss (20°) of the coating in Example C2: 7.7 The gloss (60°) of the coating in Example E3 was 42.2. The gloss (60°) of the coating in Example E4 was 42.3. The gloss (60°) of the coating in Example E4 was 40.8. The gloss (85°) of the coating in Example E3 was 81.8. The gloss (85°) of the coating in Example E4 was 81.7. The gloss (85°) of the coating in Example C2: 80.9

[0091] Compared to Example C2, the gloss of Examples E3 and E4 has been improved.

[0092] Low shear viscosity as measured by ASTM D562: Low shear viscosity of the coating from Example E3 (7 days after preparation): 96.2 KU Low shear viscosity of the coating from Example E4 (7 days after preparation): 95.6 KU Low shear viscosity of the coating from Example C2 (7 days after preparation): 94.8 KU Measurement of opacity:

[0093] Coatings were prepared on Leneta 3B black and white sealing coating cards using a 3-mil coating stick. The films were dehydrated for 24 hours at room temperature. Opacity was determined spectrophotometrically as the ratio of reflected light from the dehydrated coating on the black and white portions of the Leneta card. Opacity indicates the coating's ability to cover black surfaces. The results are as follows: The opacity of the coating in Example E3: 97.52% The opacity of the coating in Example E4: 97.53% Opacity of the coating in Example C2: 97.51%

[0094] According to ASTM D3359, the adhesion of the intercoat to aluminum and alkyd resin is comparable to that of E3, E4 and C2 coatings.

[0095] Stain removal according to ASTM D4828: Comparable to paints from E3, E4 and C2, for use on pencils, lipsticks, crayons, ballpoint pens, red wine, ketchup, coffee, and mustard (by visual inspection). Determination of detergency:

[0096] Wash the surface of the yellow pine wood with water to remove the glaze from the milling machine and let it dehydrate overnight.

[0097] Depending on the number of samples to be tested, the substrate is divided into multiple sections. Using an appropriate brush, the test paint sample is coated with the natural spread rate.

[0098] The coating was cured at room temperature for 4 hours and 24 hours respectively. Afterward, half of the coated area was covered with 2 inches of dehydrated dust (Arizona or Carpet dust). The panel was left to stand for 15 minutes, then tilted vertically and gently tapped to remove the dust.

[0099] Gently brush each dirty sample area (15 times).

[0100] The detergency is comparable to that of the coatings from Examples E3, E4 and C2 (as determined by visual evaluation).

[0101] none

Claims

1. An aqueous polymer latex, which can be obtained by polymerizing a monomer composition M by free radical emulsion polymerization in the presence of a seed latex, wherein the monomer composition M comprises, by weight of total monomer composition M: a) 0.5 to 30 wt% 2-octyl acrylate, b) 25 to 55 wt% n-butyl acrylate, c) 35 to 65 wt% methyl methacrylate, d) 0 to 5 wt% one or more monoalkenyl unsaturated carboxylic acids, e) 0 to 5 wt% one or more monoalkenyl unsaturated carboxylamines, f) 0 to 10 wt% one or more other alkene-unsaturated nonionic monomers different from monomers a), b), c), d), and e).

2. The aqueous polymer latex of claim 1, wherein monomer d) is selected from the group consisting of acrylic acid, methacrylic acid and itaconic acid.

3. The aqueous polymer latex of claim 1 or 2, wherein monomer e) is selected from the group consisting of acrylamide and methacrylamide.

4. The aqueous polymer latex of claim 1 or 2, wherein monomer d) is present in an amount of 0.1 to 4% by weight.

5. The aqueous polymer latex of claim 1 or 2, wherein monomer e) is present in an amount of 0.1 to 4% by weight.

6. The aqueous polymer latex of claim 1 or 2, wherein the monomer composition M comprises: a) 1 to 15% by weight of 2-octyl acrylate, b) 25 to 55% by weight of n-butyl acrylate, c) 40 to 65% by weight of methyl methacrylate, d) 0 to 5% by weight of one or more mono-olefin unsaturated carboxylic acids, e) 0 to 5% by weight of one or more mono-olefin unsaturated carboxylic acids amide.

7. The aqueous polymer latex of claim 1 or 2, wherein the monomer composition M comprises: a) 3 to 12 wt% 2-octyl acrylate, b) 30 to 50 wt% n-butyl acrylate, c) 40 to 60 wt% methyl methacrylate, d) 0.1 to 4 wt% mono-olefin unsaturated carboxylic acids selected from acrylic acid, methacrylic acid and itaconic acid, e) 0.1 to 4 wt% mono-olefin unsaturated carboxylic acids amides selected from acrylamide and methacrylamide.

8. The aqueous polymer latex of claim 1 or 2, wherein the monomer composition M comprises: a) 3 to 12 wt% 2-octyl acrylate, b) 30 to 50 wt% n-butyl acrylate, c) 40 to 60 wt% methyl methacrylate, d) 0.5 to 3 wt% acrylic acid, e) 0.5 to 3 wt% acrylamide.

9. The aqueous polymer latex of claim 1 or 2, wherein the monomer composition M is polymerized in the presence of a seed latex composed of one or more olefinic unsaturated monomers, in an amount of 0.1 to 10% by weight of the total weight of the monomer composition M.

10. The aqueous polymer latex of claim 9, wherein the seed latex is composed of one or more olefinic unsaturated monomers selected from the group consisting of: C2-C10 alkyl esters of acrylic acid, C1-C4 alkyl esters of methacrylic acid, and vinyl aromatic monomers.

11. The aqueous polymer latex of claim 1 or 2, wherein at least a portion of the 2-octyl acrylate is obtained from renewable raw materials.

12. A copolymer comprising an aqueous polymer latex as claimed in any one of claims 1 to 11.

13. A waterborne coating composition comprising: i) a waterborne polymer latex as claimed in any one of claims 1 to 11, ii) a titanium dioxide pigment.

14. The waterborne coating composition of claim 13, wherein the weight ratio of the copolymer contained in the waterborne polymer latex to the titanium dioxide pigment is in the range of 0.1:5.0 to 5.0:0.

1.

15. Use of an aqueous polymer latex as claimed in any one of claims 1 to 11 as an adhesive in an aqueous coating composition containing titanium dioxide pigment.