Aqueous coating composition and method for preparing a coating

Abstract

An aqueous coating composition comprising: (A) an emulsion polymer, the present invention relates to a composition comprising (i) from 0.48% to 1.5% by weight of structural units of an ethylenically unsaturated phosphorus-containing monomer, (ii) from 0.7% to 3% by weight of structural units of diacetone (meth) acrylamide, (iii) from 10% to 80% by weight of structural units of a vinyl aromatic monomer, (iv) from structural units of an alkyl (meth) acrylate, and (v) from 0 to 5% by weight of an alpha, beta-unsaturated phosphorus-containing monomer, a structural unit of a [beta]-ethylenically unsaturated carboxylic acid, a salt thereof, or a mixture thereof; (B) a specific dicarboxylic acid at a specific concentration, a salt thereof, or a mixture thereof; (C) from 30% to 60% by weight of a thio, amido or imidogen derivative of triphosphonic acid, a salt thereof or a mixture thereof; (D) a water-soluble alkali metal silicate present in an amount to provide a dry weight ratio of (D) to (C) of 1.2 to 3.7; and (E) from 40% to 52% by weight of tannic acid, gallic acid, pyrogallol or citric acid; salts thereof; or a combination thereof; wherein the weight percentages are relative to the weight of the emulsion polymer. A method of making a coating comprising a base coat made from the aqueous coating composition.

Description

Technical Field

[0001] The present invention relates to an aqueous polymer composition and a method for preparing a coating. Background Art

[0002] The solvent-based coating compositions comprising epoxy resins, polyurethanes or alkyd resins are widely used in metal protective coatings due to their corrosion resistance, mechanical properties and outward appearance. Compared to solvent-based coating compositions, the water-based coating compositions comprising acrylic polymers have much less environmental problems. However, soon after the water-based coating composition is applied to a corrosive substrate (such as a metal substrate) or immediately and before the composition is thoroughly dried, flash rust (flash rust) often forms (called "flash rust formation") as a discrete rust spot visible to the naked eye on the metal surface. Efforts have been made to develop water-based coating compositions with improved flash rust resistance. Adding enough flash rust inhibitors such as sodium nitrite to the water-based coating composition can reduce or eliminate the formation of flash rust on the metal surface, but usually damages the early water-resistant characteristics of the coating made therefrom. In addition, the water-based coating compositions known in the prior art usually lack enough adhesion to unpretreated metal substrates such as rusted metal surfaces when drying. Therefore, usually it is necessary to pre-treat the metal surface, to ensure enough adhesion between coating and the substrate, for example, by polishing the metal surface to remove rust or by applying rust conversion paint on the rusted metal surface. Conventional rust conversion paints typically use rust conversion agents such as tannic acid or phosphoric acid to react with rust, thereby forming a stable, insoluble coordination compound on the metal surface. This coordination compound, as a basecoat to which a waterborne topcoat composition may be further applied, may contribute to improved corrosion resistance, but has no beneficial effect on improving the flash rust resistance of the resulting coating. Because these acidic rust conversion paints are generally incompatible with most waterborne acrylic polymers, which are more stable under alkaline conditions, and the resulting coordination compound film is still not dense enough, the coating still exhibits insufficient adhesion to the metal substrate.

[0003] Therefore, there remains a need to provide an aqueous coating composition that can be applied directly to corrosion-susceptible substrates while providing coatings therefrom having desirable flash rust resistance, early water resistance, and adhesion characteristics. Summary of the Invention

[0004] The present invention provides a novel waterborne coating composition that does not have the above-mentioned problems. The waterborne coating composition of the present invention comprises a novel combination of at least components (A) to (E): (A) a specific emulsion polymer; (B) a specific dicarboxylic acid, its salt or mixture thereof; (C) a thio, amide or imide derivative of triphosphonic acid, its salt or mixture thereof; (D) a water-soluble alkali metal silicate; and (E) tannic acid, gallic acid, pyrogallol, citric acid, its salt or combination thereof. The waterborne coating composition can be applied directly to a corrosion-prone substrate (particularly an unpretreated substrate) while providing a coating made therefrom with excellent flash rust resistance (flash rust rating of "0"), good early water resistance (blister rating of "8M" or better) and good adhesion to the substrate (adhesion classification ≥4B). These properties can be measured according to the test methods described in the Examples section below.

[0005] In a first aspect, the present invention is an aqueous coating composition comprising:

[0006] (A) an emulsion polymer comprising: (i) 0.48 to 1.5 weight percent of structural units of an ethylenically unsaturated phosphorus-containing monomer, (ii) 0.7 to 3 weight percent of structural units of diacetone (meth)acrylamide, (iii) 10 to 80 weight percent of structural units of a vinyl aromatic monomer, (iv) structural units of an alkyl (meth)acrylate, and (v) 0 to 5 weight percent of structural units of an α,β-ethylenically unsaturated carboxylic acid, a salt thereof, or a mixture thereof;

[0007] (B) a dicarboxylic acid, a salt thereof, or a mixture thereof; wherein the dicarboxylic acid has the structure of formula (I): HOOC-R-COOH; wherein R is an alkylene, alkenylene, alkynylene, cycloalkylene, cycloalkenylene, cycloalkynylene, arylene, or heteroarylene group containing 6 to 18 carbon atoms;

[0008] and wherein (B) the dicarboxylic acid, a salt thereof, or a mixture thereof is present in an amount to provide a concentration of -OOC-R-COO- segments of 1.1 wt% to 3.8 wt%;

[0009] (C) 30% to 60% by weight of a thio, amide or imido derivative of a triphosphonic acid, a salt thereof or a mixture thereof;

[0010] (D) a water-soluble alkali metal silicate, the water-soluble alkali metal silicate being present in an amount to provide a dry weight ratio of (D) the water-soluble alkali metal silicate to (C) the thio-, amido-, or imide derivative of triphosphonic acid, a salt thereof, or a mixture thereof of 1.2 to 3.7; and

[0011] (E) 40% to 52% by weight of tannic acid, gallic acid, pyrogallol, or citric acid;

[0012] their salts; or combinations thereof;

[0013] The weight percentages are relative to the weight of the emulsion polymer.

[0014] In a second aspect, the present invention is a method of preparing a coating, the method comprising:

[0015] (i) providing the aqueous coating composition of the first aspect;

[0016] (ii) applying the aqueous coating composition directly to a corrosion-susceptible substrate; and

[0017] (iii) drying or allowing to dry the applied aqueous coating composition to form a basecoat layer on the substrate; and optionally,

[0018] (iv) applying an aqueous top coating composition comprising an acrylic emulsion polymer to the base coating obtained from step (iii); and (v) drying or allowing to dry the applied aqueous top coating composition to form a top coating such that the base coating is located between the substrate and the top coating. DETAILED DESCRIPTION

[0019] When no date is indicated by a test method number, the test method refers to the most recent test method as of the priority date of this document. Reference to a test method includes reference to both the testing association and the test method number. The following test method abbreviations and identifiers apply herein: ASTM refers to ASTM International Method, ISO refers to the International Organization for Standardization, and GB / T refers to Chinese National Standard. Products identified by their trade names refer to compositions available under those trade names on the priority date of this document. "And / or" means "and, or as an alternative". Unless otherwise indicated, all ranges are inclusive.

[0020] "Untreated surface" and "unpretreated substrate" both refer to a substrate surface that is used without any pretreatment, or a substrate surface that has been cleaned to remove dust, loose rust, contaminants, and grease prior to application of the aqueous coating composition of the present invention. Any such cleaning is performed, for example, solely by evaporating the solvent and / or by sanding to remove loose rust. Prior to application of the aqueous coating composition of the present invention, there is no additional treatment or priming of the substrate surface with a rust-converting composition (other than the aqueous coating composition of the present invention). "Loose rust" means rust that can be removed by hand without the aid of tools.

[0021] As used herein, an "aqueous" composition or dispersion refers to particles dispersed in an aqueous medium. As used herein, an "aqueous medium" refers to water and 0% to 30% by weight, based on the weight of the medium, of a water-miscible compound such as, for example, an alcohol, glycol, glycol ether, glycol ester, or mixtures thereof.

[0022] "Acrylic polymer" herein refers to a homopolymer of an acrylic monomer or a copolymer comprising structural units of an acrylic monomer and one or more additional monomers. "Acrylic" in the present invention includes (meth)acrylic acid, alkyl (meth)acrylates, (meth)acrylamide, (meth)acrylonitrile, and modifications thereof, such as hydroxyalkyl (meth)acrylates. Throughout this document, the word fragment "(meth)acryloyl" refers to both "methacryloyl" and "acryloyl." For example, (meth)acrylic acid refers to both methacrylic acid and acrylic acid, and methyl (meth)acrylate refers to both methyl methacrylate and methyl acrylate. Acrylic polymers may include acrylic homopolymers, styrene acrylic copolymers, or mixtures thereof.

[0023] The "structural unit" of a named monomer (also called a "polymerized unit") refers to the residue of the monomer after polymerization, that is, the polymerized monomer or the monomer in polymerized form. For example, the structural unit of methyl methacrylate is shown below:

[0024] The dotted lines represent the connection points between the structural units and the polymer backbone.

[0025] "Alkylene" means a branched or unbranched saturated divalent hydrocarbon group. Exemplary alkylene groups include methylene (-CH2-), ethylene (-CH2CH-), -CH2CH(CH3)CH2-, or combinations thereof. "Cycloalkylene" means a branched or unbranched divalent hydrocarbon group attached to one or more cycloalkyl groups. Exemplary cycloalkylene groups include cyclohexylene, methylcyclohexylene, or combinations thereof. "Alkenylene" means a branched or unbranched divalent hydrocarbon group having one or more carbon-carbon double bonds. Exemplary alkenylene groups include vinylene (-CH=CH-), -CH=CH-CH2-, -CH=C(CH3)-, or combinations thereof. "Cycloalkenylene" means a branched or unbranched divalent hydrocarbon group having one or more carbon-carbon double bonds attached to or within one or more cycloalkyl groups. Exemplary cycloalkenylene groups include cyclohexenylene, -CH=CH-CH6H 10- or combinations thereof. "Alkynylidene" means a branched or unbranched divalent hydrocarbon group having one or more carbon-carbon triple bonds. Exemplary alkynylene groups include ethynylene, -C≡C-, -C≡C-CH2-, or combinations thereof. "Cycloalkynylene" means a branched or unbranched divalent hydrocarbon group having one or more carbon-carbon triple bonds attached to or within one or more cycloalkyl groups. Exemplary cycloalkynylene groups include -C≡C-C6H 10 - or combinations thereof. "Arylene" means a branched or unbranched divalent hydrocarbon group connected to one or more aryl groups. Exemplary arylene groups include phenylene, -C6H4-, -CH2-C6H4-, -CH2-C6H3(CH3)-, or combinations thereof. "Heterocyclic arylene" means a branched or unbranched divalent hydrocarbon group connected to one or more heterocyclic aryl groups. Exemplary heterocyclic arylene groups include pyridylene, thiazolylene, or combinations thereof.

[0026] As used herein, the "glass transition temperature" or "T g " can be calculated by using the following Fox equation (TGFox, Bull. Am. Physics Soc., Vol. 1, No. 3, p. 123 (1956)). For example, for calculating the T of a copolymer of monomers M1 and M2 g ,

[0027]

[0028] Where T g (calculated) is the glass transition temperature calculated for the copolymer, w(M1) is the weight fraction of monomer M1 in the copolymer, w(M2) is the weight fraction of monomer M2 in the copolymer, T g (M1) is the glass transition temperature of the homopolymer of monomer M1, and T g (M2) is the glass transition temperature of the homopolymer of monomer M2; all temperatures are in K. Glass transition temperatures of homopolymers can be found, for example, in “Polymer Handbook”, edited by J. Brandrup and EH Immergut, Interscience Publishers.

[0029] "Weight of emulsion polymer" refers to the dry weight of the emulsion polymer.

[0030] The aqueous coating composition of the present invention comprises one or more emulsion polymers (component (A)), typically in an aqueous dispersion. The emulsion polymer comprises structural units of one or more ethylenically unsaturated phosphorus-containing monomers (monomer (i)). The ethylenically unsaturated phosphorus-containing monomer can be a dihydrogen phosphate ester of an alcohol, wherein the alcohol contains or is substituted with a polymerizable vinyl or olefin group. The ethylenically unsaturated phosphorus-containing monomer can include phosphaalkyl (meth)acrylates, such as phosphaethyl (meth)acrylate, phosphapropyl (meth)acrylate, phosphabutyl (meth)acrylate, their salts, and mixtures thereof; CH2=C(R p1 )-C(O)-O-(R p2 O) q -P(O)(OH)2, where R p1 =H or CH3, R p2= alkylene, such as ethylene group, propylene group or a combination thereof; and q = 1-20, such as SIPOMER PA M-100, SIPOMER PAM-200, SIPOMER PAM-300 and SIPOMER PAM-600, all of which are available from Solvay; phosphoalkoxy (meth)acrylate, such as phosphoethylene glycol (meth)acrylate, phosphodiethylene glycol (meth)acrylate, phosphotriethylene glycol (meth)acrylate, phosphopropylene glycol (meth)acrylate, phosphodipropylene glycol (meth)acrylate, phosphotripropylene glycol (meth)acrylate, their salts or mixtures thereof. Desirably, the phosphoric acid monomer is selected from phosphoethyl methacrylate (PEM), phosphoethyl acrylate, allyl ether phosphate, phosphopropyl methacrylate, phosphobutyl methacrylate or a mixture thereof; more desirably, phosphoethyl methacrylate. The emulsion polymer may comprise structural units of monomer (i), an ethylenically unsaturated phosphorus-containing monomer, at a concentration of from 0.48 wt % to 1.5 wt % based on the weight of the emulsion polymer and may be 0.48 wt % or greater, 0.50 wt % or greater, 0.52 wt % or greater, 0.55 wt % or greater, 0.58 wt % or greater, 0.60 wt % or greater, 0.62 wt % or greater, 0.65 wt % or greater, 0.68 wt % or greater, 0.70 wt % or greater, 0.72 wt % or greater, 0.75 wt % or greater, 0.78 wt % or greater, 0.80 wt % or greater, 0.82 wt % or greater, 0.85 wt % or greater, 0.88 wt % or greater, % or less, 1.18 wt % or less, 1.17 wt % or less, 1.16 wt % or less, 1.15 wt % or less, 1.12 wt % or less, 1.10 wt % or less, 1.08 wt % or less, 1.05 wt % or less, 1.02 wt % or less, 1.00 wt % or less, 0.98 wt % or less, 0.95 wt % or less or even 0.92 wt % or less, and desirably 0.63 to 1.2 wt % or 0.8 to 1.2 wt %.

[0031] The emulsion polymers useful in the present invention may contain structural units of diacetone (meth) acrylamide (monomer (ii)), and desirably diacetone acrylamide (DAAM). The emulsion polymer may contain structural units of monomer (ii), i.e., diacetone (meth) acrylamide, in a concentration of 0.7% to 3% by weight, based on the weight of the emulsion polymer, and may be 0.7% or greater, 0.75% or greater, 0.8% or greater, 0.9% or greater, 1.0% or greater, 1.1% or greater, 1.2% or greater, 1.3% or greater, 1.4% or greater, 1.5% or greater, 1.6% or greater, 1.7% or greater, or even 1.75% or greater. % or greater, while at the same time the concentration is typically 3 wt % or less and can be 2.9 wt % or less, 2.8 wt % or less, 2.7 wt % or less, 2.6 wt % or less, 2.5 wt % or less, 2.45 wt % or less, 2.3 wt % or less, 2.2 wt % or less, 2.1 wt % or less, 2.0 wt % or less, 1.9 wt % or less, 1.8 wt % or less or even 1.75 wt % or less, and desirably 1.75 to 2.45 wt % or 1.1 to 2.1 wt %.

[0032] The emulsion polymers useful in the present invention may contain structural units of one or more vinyl aromatic monomers (monomer (iii)). Suitable vinyl aromatic monomers may include, for example, styrene and substituted styrenes such as α-methylstyrene, p-methylstyrene, tert-butylstyrene, trans-β-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, o-, m-, and p-methoxystyrene; p-trifluoromethylstyrene, or mixtures thereof. Desirably, the vinyl aromatic monomer is styrene. The emulsion polymer may comprise structural units of monomer (iii), i.e., a vinyl aromatic monomer, in a concentration of from 10% to 80% by weight, based on the weight of the emulsion polymer, and may be 10% or more, 20% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, or even 55% or more, while the concentration is typically 80% or less and may be 75% or less, 70% or less, 65% or less, or even 60% or less, and desirably from 40% to 65% by weight.

[0033] The emulsion polymer useful in the present invention may contain structural units of one or more (meth)acrylic acid alkyl esters (monomers (iv)) containing an alkyl group having 1 to 24 carbon atoms, other than the above-mentioned monomer (i). The (meth)acrylic acid alkyl ester may have 1 to 20 carbon atoms, 4 to 10 carbon atoms, or 4 to 8 carbon atoms. The alkyl group may be a linear, branched, or cyclic alkyl group, and is desirably a linear or branched alkyl group. Examples of suitable alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, butyl (meth)acrylate, tert-butyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, dibutyl itaconate, diethyl itaconate, cycloalkyl (meth)acrylates such as cyclohexyl acrylate, cyclohexyl methacrylate, methylcyclohexyl (meth)acrylate, isobornyl methacrylate, isobornyl acrylate, dihydrodicyclopentadienyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, or tert-butyl (meth)cyclohexyl acrylate; mixtures thereof; or combinations thereof. Desirably, the alkyl (meth)acrylate is selected from butyl acrylate, 2-ethylhexyl (meth)acrylate, ethyl (meth)acrylate, or mixtures thereof. The total concentration of structural units of alkyl (meth)acrylates, based on the weight of the emulsion polymer, can be in the range of 10% to 70% by weight and can be 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, or even 40% or more, while the concentration is typically 70% or less and can be 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, or even 40% or less, and desirably 30% to 55% by weight. Desirably, the emulsion polymer may or may not contain structural units of cycloalkyl (meth)acrylates. The concentration of structural units of cycloalkyl (meth)acrylates in the emulsion polymer, based on the weight of the emulsion polymer, can be in the range of 0 to 5% by weight and can be less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or even zero.

[0034] The emulsion polymers useful in the present invention may or may not contain structural units of one or more α,β-ethylenically unsaturated carboxylic acids, salts thereof, or mixtures thereof (monomer (v)). Suitable α,β-ethylenically unsaturated carboxylic acids may include, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, fumaric acid, 2-carboxyethyl acrylate, or mixtures thereof. α,β-ethylenically unsaturated carboxylic acids also include monomers with acid-forming groups that generate or are subsequently converted to such acid groups (such as anhydrides, (meth)acrylic anhydride, or maleic anhydride); or mixtures thereof. Desirably, the α,β-ethylenically unsaturated carboxylic acid is selected from acrylic acid, methacrylic acid, itaconic acid, 2-carboxyethyl acrylate, or mixtures thereof. The emulsion polymer may contain monomer (v), i.e., structural units of α,β-ethylenically unsaturated carboxylic acids and salts thereof, in a concentration of 0 to 5 wt % based on the weight of the emulsion polymer and can be zero or greater, 0.3 wt % or greater, 0.5 wt % or greater, 0.8 wt % or greater, 1.0 wt % or greater, 1.2 wt % or greater, 1.5 wt % or greater, 1.8 wt % or greater, or even 2 wt % or greater, while the concentration is typically 5 wt % or less and can be 4.5 wt % or less, 4 wt % or less, 3.5 wt % or less, 3.2 wt % or less, 2.8 wt % or less, 3.0 wt % or less, 2.8 wt % or less, 2.5 wt % or less, 2.2 wt % or less, or even 2.0 wt % or less, and desirably 0.3 to 4 wt % or 1.75 to 2.5 wt %.

[0035] The emulsion polymers useful in the present invention may or may not contain structural units of one or more monoethylenically unsaturated functional monomers (monomer (vi)) other than the above-mentioned monomers (i)-(v), wherein the one or more monoethylenically unsaturated functional monomers have one or more functional groups selected from the group consisting of amide, silane, hydroxyl, urea, imide, glycidyl, amino and sulfonic acid; salts thereof; or combinations thereof. These monoethylenically unsaturated functional monomers may include, for example, amino functional monomers such as dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylate, or mixtures thereof; monomers with amide functional groups such as acrylamide and methacrylamide; monomers with glycidyl functional groups such as glycidyl acrylate, glycidyl methacrylate, or mixtures thereof; vinyl trialkoxysilanes such as vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris(2-methoxyethoxy)silane, vinyl dimethylethoxysilane, vinyl methyl diethoxysilane, or mixtures thereof; (meth)acryloyloxyalkyl trialkoxysilanes such as (meth)acryloyloxysilane,

[0014] The present invention also includes the following monomers: oxyethyl trimethoxysilane, (meth) acryloxypropyl trimethoxysilane, or mixtures thereof; urea-functional monomers; hydroxyl-functional monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxybutyl methacrylate, or mixtures thereof; ethylenically unsaturated compounds containing cyclic urea groups (i.e., imidazolidin-2-one groups), including alkyl esters of (meth) acrylic acid containing cyclic urea groups, such as N-(2-methacrylamidoethyl)ethylene urea, N-(2-methacryloyloxyethyl)ethylene urea, N-(diethyl maleate)ethylene urea, or mixtures thereof; sulfonic acid monomers including sodium vinyl sulfonate (SVS), sodium styrene sulfonate (SSS), and acrylamido-methyl-propane sulfonate (AMPS), salts thereof, or mixtures thereof; and combinations thereof. Desirably, monomer (vi) is N-(2-methacryloyloxyethyl)ethylene urea. The emulsion polymer may contain structural units of monomer (vi), i.e., a monoethylenically unsaturated functional monomer, in a concentration of 0 to 5 wt % based on the weight of the emulsion polymer and can be zero or greater, 0.05 wt % or greater, 0.1 wt % or greater, 0.2 wt % or greater, 0.3 wt % or greater, 0.4 wt % or greater, even 0.5 wt % or greater, while the concentration is typically 5 wt % or less and can be 4 wt % or less, 3.5 wt % or less, 3 wt % or less, 2.5 wt % or less, 2 wt % or less, 1.5 wt % or less, 1 wt % or less, 0.8 wt % or less, or even 0.6 wt % or less, and desirably 0.1 to 1 wt %.

[0036] The emulsion polymers useful in the present invention may also contain or not contain structural units of one or more polyethylenically unsaturated monomers (monomer (vii)). Examples of suitable polyethylenically unsaturated monomers include alkylene glycol diacrylates and dimethacrylates, such as ethylene glycol di(meth)acrylate; 1,1,1-trimethylolpropane di(meth)acrylate; pentaerythritol trimethacrylate; vinyl (meth)acrylate divinylbenzene; allyl (meth)acrylate; allyl (meth)acrylamide; allyloxyethyl (meth)acrylate, crotyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenylethyl (meth)acrylate; diallyl maleate; or mixtures thereof. The emulsion polymer may contain structural units of monomer (vii), i.e., a multiethylenically unsaturated monomer, in a concentration of from 0 to 1 wt % based on the weight of the emulsion polymer and may be 0.05 wt % or greater, 0.1 wt % or greater, or even 0.15 wt % or greater, while the concentration is typically 1 wt % or less and may be less than 1 wt %, 0.8 wt % or less, 0.5 wt % or less, 0.4 wt % or less, or even 0.3 wt % or less.

[0037] The emulsion polymers useful in the present invention may or may not contain structural units of one or more monoethylenically unsaturated benzophenones, monoethylenically unsaturated acetophenones, or mixtures thereof (monomer (viii)). Suitable monoethylenically unsaturated benzophenones may include, for example, vinyl benzophenone, o-benzoyl-benzoic acid (2-hydroxy-3-methacryloyloxy)propyl ester, o-benzoyl-benzoic acid (2-hydroxy-3-acryloyloxy)propyl ester, or mixtures thereof. The structural units of monomer (viii), i.e., a monoethylenically unsaturated benzophenone, a monoethylenically unsaturated acetophenone, or a mixture thereof, may be present in a total concentration of 0 to 3 wt % based on the weight of the emulsion polymer and may be zero or greater, 0.1 wt % or greater, 0.3 wt % or greater, 0.5 wt % or greater, or even 0.7 wt % or greater, while the concentration is typically 3.0 wt % or less and may be 2.0 wt % or less, 1.5 wt % or less, 1.2 wt % or less, 1.0 wt % or less, or even 0.9 wt % or less, and desirably 0 to 1 wt %.

[0038] Advantageously, the emulsion polymer useful in the present invention comprises, based on the weight of the emulsion polymer: 0.8 to 1.2 wt% of structural units of phosphoethyl methacrylate; 1.1 to 2.1 wt% of structural units of diacetone acrylamide; 40 to 65 wt% of structural units of styrene; 30 to 55 wt% of structural units of butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, or mixtures thereof; and 0.3 to 4 wt% of structural units of acrylic acid, methacrylic acid, or mixtures thereof.

[0039] Emulsion polymers can be single-stage polymers or multi-stage polymers. Desirably, emulsion polymers are multi-stage polymers, such as two-stage polymers comprising polymer A and polymer B. In this article, "single-stage polymer" refers to an emulsion polymer prepared by single-stage emulsion polymerization. In this article, "multi-stage polymer" refers to an emulsion polymer prepared by sequentially adding two or more different monomer compositions in different stages, such as in the first stage and the second stage, to carry out multi-stage emulsion polymerization, thereby forming at least polymer A and polymer B. "Polymer A" and "Polymer B" mean that these polymers have different compositions and are formed in different stages of multi-stage emulsion polymerization, and desirably, polymer A is formed in the first stage of multi-stage emulsion polymerization, while polymer B is formed in the second stage of multi-stage emulsion polymerization. Each stage is polymerized sequentially and is different from the subsequent and / or subsequent stages due to the different monomer compositions. Without being bound by theory, a multi-stage polymer can include multiple different phases or layers, which can be demonstrated by at least two Tgs measured by scanning transmission electron microscopy (STEM) or by differential scanning calorimetry (DSC). Desirably, polymer A is the outer layer of the multi-stage emulsion polymer and polymer B is the inner layer of the multi-stage polymer. The multi-stage polymer may be composed of polymer A and polymer B. The types and concentrations of the structural units of the above-mentioned monomers in the emulsion polymer portion may be selected in polymer A and / or polymer B so as to provide a resulting multi-stage polymer (i.e., emulsion polymer) having a Tg value as described above in the emulsion polymer section. Desirably, the Tg of polymer A is less than 20°C and may be 17°C or less, 14°C or less, 11°C or less, or even 8°C or less, while typically being -20°C or greater and may be -15°C or greater, -10°C or greater, -5°C or greater, 0°C or greater, 4°C or greater, or even 6°C or greater. The Tg of polymer B may be higher than 30° C. and may be 35° C. or higher, 40° C. or higher, 45° C. or higher, 49° C. or higher, or even 52° C. or higher, while at the same time typically being less than 80° C. and may be 75° C. or lower, 70° C. or lower, 65° C. or lower, 60° C. or lower, 57° C. or lower, or even 54° C. or lower. The Tg value is calculated by the Fox equation.

[0040] When the emulsion polymer is a multi-stage polymer, the structural units of the above-described monomers in the emulsion polymer portion may be present in one or both of polymers A and B at concentrations such that the total concentration of the structural units of each of these monomers relative to the weight of the multi-stage polymer (i.e., the weight of the emulsion polymer) is the same as the weight concentration of the structural units of such monomers relative to the weight of the emulsion polymer. For example, one or both of polymers A and B in the multi-stage polymer include structural units of monomer (iv), i.e., an alkyl (meth)acrylate. Polymer A and / or polymer B, and desirably, polymer A may or may not include structural units of monomer (v), i.e., an α,β-ethylenically unsaturated carboxylic acid, a salt thereof, or a mixture thereof. For example, polymer A may include 1% to 7% by weight of the structural units of monomer (v), based on the weight of polymer A; and polymer B may include 0 to 3% by weight of the structural units of monomer (v), based on the weight of polymer B. Polymer A and / or polymer B may or may not include structural units of one or more of the above-described monomers (vi), (vii), and (viii). Desirably, the multistage polymer comprises from 50 wt% to 90 wt% of polymer A and from 10 wt% to 50 wt% of polymer B, based on the weight of the multistage polymer (i.e., the emulsion polymer weight), wherein polymer A comprises from 0.3 wt% to 2.4 wt% of structural units of monomer (i), i.e., an ethylenically unsaturated phosphorus-containing monomer, from 1 wt% to 6 wt% of structural units of monomer (ii), i.e., diacetone (meth)acrylamide, from 10 wt% to 75 wt% of structural units of monomer (iii), i.e., vinyl aromatic polyols, based on the weight of polymer A. The present invention relates to a polymer composition comprising a first polymer (A) and a second polymer (B) comprising a first polymer (B) and a second polymer (C) comprising a first polymer (D) and a second polymer (D) comprising a second monomer (D) comprising a first monomer (D) and a second monomer (D) comprising a second monomer (D) comprising a second monomer (D) and a second monomer (D) comprising a first ...

[0041] One or both of polymer A and polymer B in the multi-stage polymer (desirably polymer A) may contain structural units of an ethylenically unsaturated phosphorus-containing monomer. Polymer A may comprise structural units of monomer (i), i.e., an ethylenically unsaturated phosphorus-containing monomer, at a concentration of 0.3% to 2.4% by weight, based on the weight of polymer A, and may be 0.3% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, 1.0% or more, 1.1% or more, 1.2% or more, 1.3% or more, 1.4% or more, 1.5% or more, even 1.6% or more, while the concentration is typically 2.4% or less and may be 2.3% or less, 2.2% or less, 2.1% or less, 2.0% or less, 1.9% or less, 1.8% or less, or even 1.7% or less, and desirably 0.9% to 1.8% by weight. Polymer B may or may not contain structural units of monomer (i), i.e., an ethylenically unsaturated phosphorus-containing monomer, at a concentration of from 0 to 2.5 wt % based on the weight of polymer B and may be zero or greater, 0.1 wt % or greater, 0.2 wt % or greater, 0.3 wt % or greater, 0.4 wt % or greater, even 0.5 wt % or greater, while the concentration is typically 2.5 wt % or less and may be 2.2 wt % or less, 2.0 wt % or less, 1.8 wt % or less, 1.5 wt % or less, 1.2 wt % or less, 1.0 wt % or less, 0.9 wt % or less, or even 0.6 wt % or less, and desirably from 0 to 1.0 wt %.

[0042] One or both of the polymer A and the polymers in the multi-stage polymer (desirably polymer A) may contain structural units of diacetone (meth)acrylamide. Polymer A may comprise structural units of monomer (ii), i.e., diacetone (meth)acrylamide, in a concentration of 1.0% to 6.0% by weight, based on the weight of polymer A, and may be 1.0% or more, 1.2% or more, 1.5% or more, 1.8% or more, 2.0% or more, 2.2% or more, 2.5% or more, 2.8% or more, or even 3% or more by weight, while the concentration is typically 6.0% or less and may be 5.5% or less, 5.2% or less, 5% or less, 4.8% or less, 4.5% or less, 4.2% or less, 4% or less, 3.8% or less, 3.6% or less, 3.5% or less, or even 3.2% or less, and desirably 1.5% to 4% or 2.0% to 3.5% by weight. Polymer B may contain structural units of monomer (ii), i.e., diacetone (meth)acrylamide, in a concentration of 0 to 2.5 wt % based on the weight of polymer B and may be zero or greater, 0.1 wt % or greater, 0.2 wt % or greater, 0.3 wt % or greater, 0.4 wt % or greater, or even 0.5 wt % or greater, while the concentration is typically 2.5 wt % or less and may be 2.2 wt % or less, 2.0 wt % or less, 1.5 wt % or less, 1.0 wt % or less, or even 0.6 wt % or less, and desirably 0 to 1.5 wt % or 0.5 to 1.0 wt %.

[0043] One or both of polymer A and polymer B in the multi-stage polymer may contain structural units of vinyl aromatic monomers. Polymer A may contain structural units of monomer (iii), i.e., vinyl aromatic monomers, in a concentration of 10% to 75% by weight, based on the weight of polymer A, and may be 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, or even 50% or more, while the concentration is typically 75% or less and may be 70% or less, 65% or less, 60% or less, or even 55% or less, and desirably 30% to 55% by weight. Polymer B may comprise structural units of monomer (iii), i.e., a vinyl aromatic monomer, in a concentration of 10% to 100% by weight, based on the weight of polymer B, and may be 10% or more, 25% or more, 30% or more, 40% or more, 50% or more, 60% or more, or even 70% or more, while the concentration is typically 100% or less and may be 95% or less, 90% or less, 85% or less, or even 80% or less, and desirably 50% to 85% by weight.

[0044] Polymer A can be present in the multistage polymer at a concentration of 50 to 90 wt %, based on the weight of the multistage polymer, and can be 52 to 78 wt %, 55 to 75 wt %, 58 to 74 wt %, 60 to 72 wt %, 62 to 71 wt %, or 65 to 70 wt %. Polymer B can be present in the multistage polymer at a concentration of 10 to 50 wt %, and can be 22 to 48 wt %, 25 to 45 wt %, 26 to 42 wt %, 28 to 40 wt %, 29 to 38 wt %, or 30 to 35 wt %. Desirably, the multistage polymer comprises 55 to 85 wt % of Polymer A and 15 to 45 wt % of Polymer B, based on the weight of the multistage polymer.

[0045] The number average molecular weight (Mn) of the emulsion polymers useful in the present invention can be from 8,000 grams per mole (g / mol) to 60,000 g / mol and can be 8,000 g / mol or greater, 10,000 g / mol or greater, 11,000 g / mol or greater, 12,000 g / mol or greater, 14,000 g / mol or greater, 15,000 g / mol or greater, 17,000 g / mol or greater, 18,000 g / mol or greater, 20,000 g / mol or greater, 22,000 g / mol or greater, 24,000 g / mol or greater, or even 26,000 g / mol or greater. The molecular weight of the emulsion polymer is preferably 60,000 g / mol or less, 55,000 g / mol or less, 50,000 g / mol or less, 45,000 g / mol or less, 40,000 g / mol or less, 38,000 g / mol or less, 35,000 g / mol or less, 32,000 g / mol or less, 30,000 g / mol or less, 29,000 g / mol or less, 28,000 g / mol or less, 27,000 g / mol or less or even 26,000 g / mol or less, and desirably 10,000 g / mol to 30,000 g / mol. The molecular weight of the emulsion polymer can be measured by gel permeation chromatography (GPC) (additional details are provided below in the GPC analysis).

[0046] The types and amounts of the monomers used to prepare the emulsion polymer described above can be selected to provide an emulsion polymer having a glass transition temperature (Tg) suitable for various applications. The Tg of the emulsion polymer can be -10 degrees Celsius (°C) or higher and can be -5°C or higher, 0°C or higher, 5°C or higher, 10°C or higher, or even 15°C or higher, while typically being 50°C or lower and can be 45°C or lower, 40°C or lower, 35°C or lower, 30°C or lower, 25°C or lower, or even 20°C or lower, as calculated by the Fox equation.

[0047] The total concentration of the structural units of the above-mentioned monomers (e.g., monomers (i)-(iv) and optional monomers (v)-(viii), if present) in the emulsion polymer is equal to 100 wt % based on the weight of the emulsion polymer. When the emulsion polymer is a multi-stage polymer, the total concentration of the structural units of the above-mentioned monomers in both polymers A and polymer B can be equal to 100 wt % relative to the weight of the multi-stage polymer (i.e., the weight of the emulsion polymer). The structural units of the monomers in polymers A and polymer B each add up to 100 wt % based on the weight of polymers A and B, respectively.

[0048] The emulsion polymers useful in the present invention can be prepared by emulsion polymerization of a monomer mixture comprising the above-mentioned monomers (e.g., monomers (i)-(iv) and optional monomers (v)-(viii), if present). The total concentration of monomers in the monomer mixture used to prepare the emulsion polymer is equal to 100 wt %, based on the total weight of the monomer mixture. For each monomer, the weight concentration of the monomer in the monomer mixture relative to the total weight of the monomer mixture is the same as the above-mentioned weight concentration of the structural unit of such monomer in the emulsion polymer relative to the weight of the emulsion polymer. The monomer mixture can be added neat or in the form of an emulsion in water; or added in one or more addition forms or continuously, linearly or non-linearly during the reaction time period for preparing the emulsion polymer. The temperature suitable for the emulsion polymerization process can be less than 100°C and can be in the range of 10°C to 99°C or 50°C to 90°C. One or more surfactants can be used to prepare the emulsion polymer. The emulsion polymer can be prepared by a one-stage emulsion polymerization process, or by a multi-stage emulsion polymerization process, thereby forming a multi-stage polymer. A multi-stage emulsion polymerization process comprises at least two stages formed sequentially, which typically result in the formation of a multi-stage polymer comprising at least polymer A and polymer B, optionally wherein the different stages may be formed in different reactors. Desirably, the multi-stage emulsion polymerization process comprises a stage for preparing polymer A (desirably, a first stage) and a stage for preparing polymer B (desirably, a second stage) in an aqueous medium; both by emulsion polymerization. The process may comprise a stage for polymerizing monomer mixture A to form polymer A and a stage for polymerizing monomer mixture B to form polymer B. Desirably, the process for preparing the multi-stage polymer comprises a polymerization stage in which polymer A is first formed, and optionally polymer A is neutralized, followed by a polymerization stage in which polymer B is formed in the presence of polymer A. Monomer mixtures A and B may each independently comprise monomers described above for forming the structural units of polymers A and B, respectively (e.g., monomers (i) to (viii), if present). The total concentration of the monomer mixtures used to prepare polymers A and B relative to the weight of the multi-stage polymer (e.g., the total weight of polymers A and B) may be equal to 100% relative to the total weight of the monomers used to prepare the multi-stage polymer. For each monomer, the concentration of the monomer relative to the total weight of monomers used to prepare the polymer (eg, Polymer A) is substantially the same as the concentration of the structural unit of such monomer relative to the total weight of such polymer (eg, Polymer A).

[0049] One or more free radical initiators may be used in the polymerization process. The polymerization process may be thermally initiated or redox-initiated emulsion polymerization. Examples of suitable free radical initiators include hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium and / or alkali metal persulfates, sodium perborate, perphosphoric acid and their salts; potassium permanganate; and ammonium or alkali metal peroxodisulfate. The free radical initiator may generally be used in an amount of 0.01% to 3.0% by weight, based on the total weight of the monomers. A redox system comprising the above-mentioned initiators and a suitable reducing agent may be used in the polymerization process. The example of suitable reducing agent comprises sodium formaldehyde sulfoxylate, ascorbic acid, isoascorbic acid, alkali metal salt and ammonium salt (such as sodium sulfite, bisulfite, thiosulfate, sulfoxylate, sulfide, hydrogen sulfide or dithionite) of sulfur-containing acid, formamidine sulfinic acid, acetone bisulfite, glycolic acid, hydroxymethanesulfonic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid and salt of the aforementioned acid.Metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium or cobalt can be used for catalyzing redox reaction.Metal chelating agent can be used optionally.

[0050] In the polymerization process for preparing the emulsion polymer, one or more surfactants may be used. The surfactant may be added before or during the polymerization of the monomers, or a combination thereof. A portion of the surfactant may also be added after the polymerization. The surfactant may be used in at least one or all stages of the preparation of the multi-stage polymer. The surfactant may include anionic and / or nonionic emulsifiers. The surfactant may be a reactive surfactant, such as a polymerizable surfactant. Examples of suitable surfactants include alkali metal or ammonium salts of alkyl, aryl or alkylaryl sulfates, sulfonates or phosphates; alkyl sulfonic acids; sulfosuccinates; fatty acids; and ethoxylated alcohols or phenols. Desirably, alkali metal or ammonium salts of alkyl, aryl or alkylaryl sulfate surfactants are used. The combined amount of the surfactants used is typically 0 to 10 wt % or 0.5 to 3 wt % based on the weight of all monomers (i.e., monomer mixture) used to prepare the emulsion polymer.

[0051] One or more chain transfer agents can be used in the polymerization process to control the molecular weight of the emulsion polymer. When the emulsion polymer is prepared by multistage polymerization (i.e., a multistage polymer), the chain transfer agent can be used in the stage of preparing polymer A, the stage of preparing polymer B, or both stages. Examples of suitable chain transfer agents include 3-mercaptopropionic acid, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, n-dodecyl mercaptan, n-hexadecyl mercaptan, tert-dodecyl mercaptan, n-octadecyl mercaptan, benzene mercaptan, nonanedialkyl mercaptan, mercaptans containing hydroxyl groups (such as hydroxyethyl mercaptan), mercaptopropionic acid, and mixtures thereof. The chain transfer agent may be used in a concentration of from 0 to 2 weight percent, based on the total weight of the monomers used to prepare the emulsion polymer, and may be zero or greater, 0.05 weight percent or greater, 0.1 weight percent or greater, or even 0.15 weight percent or greater, while the concentration is typically 2 weight percent or less and may be 1.5 weight percent or less, 1.0 weight percent or less, 0.5 weight percent or less, 0.3 weight percent or less, 0.25 weight percent or less, or even 0.20 weight percent or less.

[0052] After completion of the polymerization, the resulting aqueous dispersion (i.e., polymer emulsion) can be neutralized with one or more bases as neutralizing agents to a pH value of, for example, at least 5, 6 to 12, 7 to 10, or 8 to 9. The base can result in partial or complete neutralization of the ionic or potentially ionic groups of the emulsion polymer. Examples of suitable bases include ammonia; alkali metal or alkaline earth metal compounds, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate; primary, secondary, and tertiary amines, such as triethylamine, ethylamine, propylamine, monoisopropylamine, monobutylamine, hexylamine, ethanolamine, diethylamine, dimethylamine, tributylamine, triethanolamine, dimethoxyethylamine, 2-ethoxyethylamine, 3-ethoxypropylamine, dimethylethanolamine, diisopropanolamine, morpholine, ethylenediamine, 2-diethylaminoethylamine, 2,3-diaminopropane, 1,2-propylenediamine, neopentyldiamine, dimethylaminopropylamine, hexamethylenediamine, 4,9-dioxadodecane-1,12-diamine, polyethyleneimine, or polyethyleneamine; aluminum hydroxide; or mixtures thereof.

[0053] The particle size of the emulsion polymer particles in the aqueous composition can be from 40 nanometers (nm) to 500 nm, and can be 60 nm or greater, 80 nm or greater, 90 nm or greater, 100 nm or greater, greater than 100 nm, 105 nm or greater, or even 110 nm or greater, while being 500 nm or less and can be 300 nm or less, 200 nm or less, or even 150 nm or less. Particle size herein refers to the Z-average size and can be measured by a Brookhaven BI-90 Plus particle size analyzer.

[0054] The aqueous coating compositions of the present invention may contain the emulsion polymer in a concentration of 1 wt % to 30 wt % based on the weight of the aqueous coating composition and may be 1 wt % or greater, 2 wt % or greater, 3 wt % or greater, 4 wt % or greater, or even 5 wt % or greater, while the concentration is typically 30 wt % or less and may be 25 wt % or less, 20 wt % or less, 15 wt % or less, or even 10 wt % or less.

[0055] Waterborne coating composition of the present invention can also comprise the polyfunctional carboxyl hydrazide that every molecule contains at least two hydrazide groups.Polyfunctional carboxyl hydrazide can be selected from adipic acid dihydrazide, oxalic acid dihydrazide, isophthalic acid dihydrazide, polyacrylic acid polyhydrazide or their mixture.Based on the weight of emulsion polymer, polyfunctional carboxyl hydrazide can exist with following concentration: zero or greater and can be 0.05 % by weight or greater, 0.1 % by weight or greater, 0.2 % by weight or greater, 0.4 % by weight or greater, even 0.6 % by weight or greater, and concentration is generally 3 % by weight or less and can be 2 % by weight or less, 1.5 % by weight or less or even 1 % by weight or less simultaneously.

[0056] The aqueous coating composition of the present invention comprises one or more dicarboxylic acids, salts thereof, or mixtures thereof (component (B)), typically in the form of an aqueous solution. "Dicarboxylic acid" refers to a compound containing two carboxyl functional groups (-COOH). The dicarboxylic acids useful in the present invention may have the structure of formula (I):

[0057] HOOC-R-COOH (I)

[0058] Wherein R is a carbon atom containing 6 to 18 carbon atoms (C6-C 18 ) alkylene, alkenylene, alkynylene, cycloalkylene, cycloalkenylene, cycloalkynylene, arylene or heterocyclic arylene groups. R can contain 6 to 18 carbon atoms and can have 7 carbon atoms or more, 8 carbon atoms or more, 9 carbon atoms or more, even 10 carbon atoms or more, and at the same time usually have 18 carbon atoms or less and can be 17 carbon atoms or less, 16 carbon atoms or less, 15 carbon atoms or less or even 14 carbon atoms or less. Desirably, dicarboxylic acid is straight chain (that is, non-branched) or branched aliphatic dicarboxylic acid. Desirably, R is C6-C 18 Alkylene groups (i.e., -(CH2) n -, where n = 6-18), and more desirably C6-C 14 Alkylene group. Desirably, the dicarboxylic acid is a saturated dicarboxylic acid. The aqueous coating composition may contain a mixture of two or more dicarboxylic acids that differ in R group, a mixture of salts of two or more different dicarboxylic acids, or a combination thereof.

[0059] Suitable dicarboxylic acids may include, for example, sebacic acid (HOOC(CH2)8COOH), dodecanedioic acid (HOOC(CH2) 10 COOH), suberic acid (HOOC(CH2)6COOH), azelaic acid (HOOC(CH2)7COOH), undecanedioic acid (HOOC(CH2)9COOH), eicosanedioic acid (HOOC(CH2) 18 COOH) or mixtures thereof; and desirably sebacic acid.

[0060] The aqueous coating composition generally comprises the reaction mixture of at least one dicarboxylic acid (desirably, sebacic acid) and at least one alkali. The alkali for neutralizing the dicarboxylic acid (that is, reacting with the dicarboxylic acid) can include those alkalis of the aqueous dispersion for neutralizing the emulsion polymer part, specifically ammonia, N, N-dimethylethanolamine, 2-amino-2-methyl-1-propanol or their mixture. The amount of the alkali for neutralizing the dicarboxylic acid to form the salt of the dicarboxylic acid (also as " dicarboxylate ") can be provided in the scope of 30:70 to 70:30 and can be 35:65 to 65:35,40:60 to 60:40 or 45:55 to 55:45 alkali and the dry weight ratio of the dicarboxylic acid. The aqueous coating composition generally comprises the salt of one or more dicarboxylic acids. Depending on the type of used alkali, the salt of the gained dicarboxylic acid can be ammonium salt, alkali metal salt, amine salt or their mixture. These salts can be the single neutralized salt of dicarboxylic acid, the double neutralized salt of dicarboxylic acid or their mixture.

[0061] Based on the weight of the emulsion polymer, component (B), i.e., the dicarboxylic acid and / or its salt, can be present in an amount that provides the following concentration of -OOC-R-COO- segments in the aqueous coating composition: 1.1 wt % to 3.8 wt % and can be 1.1 wt % or greater, 1.2 wt % or greater, 1.5 wt % or greater, even 1.8 wt % or greater, while typically 3.8 wt % or less, and can be 3.5 wt % or less, 3.2 wt % or less, 3.0 wt % or less, 2.8 wt % or less, 2.5 wt % or less, or even 2.0 wt % or less, and desirably 1.1 wt % to 2.0 wt %. The -OOC-R-COO- segments can be generated from dicarboxylic acids and / or salts of dicarboxylic acids. The concentration of the -OOC-R-COO- segments can be determined by liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (NMR) and / or extractive analysis. Alternatively, the concentration of -OOC-R-COO- segments can be calculated by the weight of the originally added unneutralized dicarboxylic acid relative to the weight of the aqueous coating composition. In the case where the aqueous coating composition contains a salt of a dicarboxylic acid, the weight of the dicarboxylic acid used to form such salt, rather than the weight of the salt, is used to calculate the concentration of -OOC-R-COO- segments.

[0062] The aqueous coating composition of the present invention comprises one or more thio, amide or imido derivatives of triphosphonic acid, their salts or their mixtures (component (C), also referred to as "triphosphonic acid derivatives"). The triphosphonic acid derivatives can be selected from tris(thio)phosphonic acid, tris-bisphosphonic acid, (thio)imido-triphosphonic acid or (thio)hydrazide-triphosphonic acid; their salts; or their combinations. Desirably, the triphosphonic acid derivatives are selected from aminotrimethylenephosphonic acid (ATMP) and aminotriethylenephosphonic acid; their salts; or their combinations. The aqueous coating composition can comprise a mixture of two or more thio, amide or imido derivatives of triphosphonic acid, a mixture of their salts or their combinations. The concentration of component (C), i.e., the triphosphonic acid derivative, can be in the range of 30% to 60% by weight and can be 30% or more, 31% or more, 32% or more, 33% or more, 34% or more, even 35% or more, while typically being 60% or less and can be 58% or less, 56% or less, 55% or less, 52% or less, 50% or less, 45% or less, 40% or less, or even 38% or less, and desirably 35% to 50% by weight, based on the weight of the emulsion polymer.

[0063] The aqueous coating composition of the present invention may include a water-soluble alkali metal silicate (component (D)). The alkali metal silicate may be sodium silicate, potassium silicate, lithium silicate, or a combination thereof. Suitable alkali metal silicates may be any silicate of the general formula MO·xSiO2, wherein M represents an alkali metal, including lithium, sodium, potassium, and combinations thereof; and x represents the molar ratio of silicon dioxide (SiO2) to metal oxide (MO). Sodium silicate (Na2O·xSiO2) typically has a molar ratio of Na2O to SiO2 in the range of 1:4 to 2:1. Potassium silicate (KO·xSiO2) typically has a molar ratio of KO to SiO2 of 0.2 to 1. Lithium silicate (Li2O·xSiO2) typically has a molar ratio of Li2O to SiO2 of 0.3 to 8. Mixed water-soluble alkali metal silicates may be used, such as sodium potassium silicate, lithium potassium silicate, or a mixture thereof. Potassium silicates of all variable compositions, including those between K2Si2O5 and K2Si3O7, can be used. Desirably, the water-soluble silicate is sodium silicate. Suitable sodium silicates can include, for example, sodium orthosilicate (Na4SiO4), sodium metasilicate (Na2SiO3), sodium disilicate (Na2Si2O5), sodium tetrasilicate (Na2Si4O9), sodium pyrosilicate (Na6Si2O7), other polysilicates, or mixtures thereof. The aqueous coating composition can include a mixture of two or more water-soluble alkali metal silicates. The water-soluble alkali metal silicate can be provided as an aqueous solution, typically containing 5% to 80%, 10% to 70%, or 15% to 60% alkali metal silicate by dry weight, based on the weight of the aqueous solution.

[0064] Components (C) and (D) are present in amounts to provide a dry weight ratio of component (C) to component (D) (i.e., the ratio of the dry weight of the alkali metal silicate to the dry weight of the triphosphonic acid derivative) in the range of from 1.2 to 3.7 and can be 1.2 or greater, 1.4 or greater, 1.5 or greater, 1.6 or greater, 1.7 or greater, 1.8 or greater, 1.9 or greater, even 2.0 or greater, while being 3.7 or less and can be 3.6 or less, 3.5 or less, 3.4 or less, 3.3 or less, 3.2 or less, 3.1 or less, 3.0 or less, 2.8 or less, 2.5 or less, 2.2 or less or even 2.0 or less, and desirably from 1.5 to 3.0.

[0065] The aqueous coating composition of the present invention may include tannic acid, gallic acid, pyrogallol, or citric acid; a salt thereof; or a combination thereof (component (E)). Component (E) may be a mixture of two or more of tannic acid, gallic acid, pyrogallol, and citric acid; a mixture of salts thereof; or a combination thereof. Desirably, component (E) includes or consists of tannic acid, a salt thereof, or a combination thereof. Component (E) can be present in the aqueous coating composition at a concentration of 40 wt % to 52 wt % based on the weight of the emulsion polymer and can be 40 wt % or greater, 42 wt % or greater, 44 wt % or greater, 45 wt % or greater, 46 wt % or greater, even 48 wt % or greater, while at the same time being 52 wt % or less and can be 51 wt % or less, 50 wt % or less, 49 wt % or less, 48 ​​wt % or less, 47 wt % or less, 46 wt % or less or even 45 wt % or less, and desirably 45 wt % to 49 wt %.

[0066] The waterborne coating composition of the present invention may include or not include one or more pigments. "Pigment" herein refers to a material that can make a substantial contribution to the opacity or hiding power of the composition. Typically, such materials have a refractive index greater than 1.8. Inorganic pigments generally include metal oxides. Examples of suitable inorganic pigments include titanium dioxide (TiO2), zinc sulfide, lithopone, carbon black, red iron oxide, black iron oxide, lemon chrome yellow, or a mixture thereof. Organic pigments generally include Prussian blue, organic pigment yellow, organic pigment red, anticorrosive pigments, or a mixture thereof. Preferably, the pigment is selected from TiO2, carbon black, or a mixture thereof. Based on the weight of the waterborne coating composition, the pigment may be present in the following total concentrations: 0 to 60 wt%, 10 wt% to 50 wt%, 15 wt% to 40 wt%, or 20 wt% to 35 wt%. The pigment may include or not include an anticorrosive pigment. "Anticorrosive pigment" refers to a pigment that can prevent or delay steel corrosion by chemical reaction or chelation. Suitable anti-corrosion pigments may include, for example, zinc phosphate, zinc molybdate, zinc oxide, aluminum tripolyphosphate, molybdenum zinc phosphate, calcium-modified zinc phosphate, organic molecule-modified zinc phosphate, or mixtures thereof. The anti-corrosion pigment may be present in a concentration of 0 to 10 wt % based on the weight of the aqueous coating composition and may be zero or greater, 0.5 wt % or greater, 1 wt % or greater, 2 wt % or greater, 3 wt % or greater, or even 4 wt % or greater, while the concentration is typically 10 wt % or less and may be 9 wt % or less, 8 wt % or less, 7 wt % or less, or even 6 wt % or less and may be 5.5 wt % or less, 5 wt % or less, 4.5 wt % or less, 4 wt % or less, 3.5 wt % or less, 3 wt % or less, 2.5 wt % or less, 2 wt % or less, 1.5 wt % or less, 1 wt % or less, or even 0.5 wt % or less.

[0067] The aqueous coating composition of the present invention may include or contain one or more extenders." extender" herein refers to a particle inorganic material having a refractive index less than or equal to 1.8 and greater than 1.3. The example of a suitable extender includes barium sulfate, talcum, calcium carbonate, clay, calcium sulfate, aluminum silicate, other silicates (except component (D)), zeolite, mica, diatomaceous earth, solid or hollow glass, ceramic beads, nepheline syenite, feldspar, diatomaceous earth, calcined diatomaceous earth, talcum (hydrated magnesium silicate), silicon dioxide, aluminum oxide, kaolin, pyrophyllite, perlite, barite, wollastonite, opaque polymers (such as ROPAQUE® available from The Dow Chemical Company) TMUltra E (ROPAQUE is a trademark of The Dow Chemical Company) or mixtures thereof. The aqueous coating composition can contain the extender at a concentration of 0 to 60 wt % based on the weight of the aqueous coating composition and can be 10 to 50 wt %, 15 to 40 wt %, or 20 to 35 wt %.

[0068] Waterborne coating composition of the present invention may include or contain one or more defoamers." defoamer " herein refers to the chemical additive that reduces foam and stops foam from forming. Defoamer can be a defoamer based on organosilicon, a defoamer based on mineral oil, a defoamer based on ethylene oxide / propylene oxide, polyalkyl acrylate and their mixture. Suitable commercially available defoamer can include, for example, TEGO Airex 901W, TEGO Airex 902W and TEGO Foamex 1488 polyether siloxane copolymer emulsions available from Di Gao (TEGO), BYK-022 and BYK-024 organosilicon defoamers available from Bi Ke (BYK) and their mixture. Based on the weight of waterborne coating composition, defoamer can exist with following concentration conventionally: 0 to 0.5 % by weight and can be 0.02 % by weight to 0.4 % by weight or 0.04 % by weight to 0.2 % by weight.

[0069] The aqueous coating composition of the present invention may or may not contain one or more thickeners (also referred to as "rheology modifiers"). Thickeners may include polyvinyl alcohol (PVA), clay materials, acid derivatives, acid copolymers, urethane associative thickeners (UAT), polyether urea polyurethane (PEUPU), polyether polyurethane (PEPU), or mixtures thereof. Examples of suitable thickeners include alkali swellable emulsions (ASE), such as sodium or ammonium neutralized acrylic polymers; hydrophobically modified alkali swellable emulsions (HASE), such as hydrophobically modified acrylic copolymers; associative thickeners, such as hydrophobically modified ethoxylated urethanes (HEUR); and cellulosic thickeners, such as methylcellulose ethers, hydroxymethylcellulose (HMC), hydroxyethylcellulose (HEC), hydrophobically modified hydroxyethylcellulose (HMHEC), sodium carboxymethylcellulose (SCMC), sodium carboxymethyl 2-hydroxyethylcellulose, 2-hydroxypropyl methylcellulose, 2-hydroxyethylmethylcellulose, 2-hydroxybutyl methylcellulose, 2-hydroxyethylethylcellulose, and 2-hydroxypropyl cellulose. Desirably, the thickener is HEUR.The thickener may be present in a concentration of 0 to 1.0 wt % and may be 0.05 wt % to 0.6 wt % or 0.1 wt % to 0.4 wt %, based on the weight of the aqueous coating composition.

[0070] The aqueous coating composition of the present invention may or may not contain one or more wetting agents. "Wetting agent" herein refers to a chemical additive that reduces the surface tension of the composition, thereby making the composition more easily diffuse across the substrate surface or penetrate the substrate surface. The wetting agent can be an anionic, zwitterionic or nonionic polycarboxylate. Suitable commercially available wetting agents can include, for example, SURFYNOL 104 and SURFY NOL TG nonionic wetting agents based on acetylenic diols (actacetylenic diol) purchased from Evonik; BYK-190, TEGO-750W and TEGO-755W solutions of high molecular weight block polymers with pigment affinity groups purchased from Bi Ke and Evonik respectively; BYK-346 and BYK-349 polyether-modified siloxanes all purchased from Bi Ke, or mixtures thereof. The wetting agent can be present in a concentration of 0 to 0.6 wt % and can be 0.1 wt % to 0.5 wt % or 0.2 wt % to 0.4 wt %, based on the weight of the aqueous coating composition.

[0071] Waterborne coating composition of the present invention may include or not include one or more coalescents." coalescent " herein refers to the slow evaporation solvent that makes polymer particles merge into continuous film under ambient conditions.The example of applicable coalescent comprises 2-n-butoxyethanol, dipropylene glycol n-butyl ether, propylene glycol n-butyl ether, dipropylene glycol methyl ether, propylene glycol methyl ether, propylene glycol n-propyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, triethylene glycol monobutyl ether, dipropylene glycol n-propyl ether, n-butyl ether or their mixture.Preferred coalescent comprises dipropylene glycol n-butyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, n-butyl ether or their mixture.Based on the weight of waterborne coating composition, coalescent can exist with following concentration: 0 to 10 % by weight and can be 0.2 % by weight to 8 % by weight or 1 % by weight to 6 % by weight.

[0072] The aqueous coating compositions of the present invention may or may not contain one or more dispersants. The dispersant may be polyacrylic acid or polymethacrylic acid or maleic anhydride with various monomers such as styrene, acrylate or methacrylate, diisobutylene and other hydrophilic or hydrophobic comonomers; their salts; or mixtures thereof. The dispersant may be present in a concentration of 0 to 2 wt % based on the weight of the aqueous coating composition and may be 0.1 to 1.5 wt % or 0.2 to 1 wt %.

[0073] In addition to the above components, the aqueous coating composition of the present invention can include any one or combination of the following additives: a buffer, a neutralizing agent, a wetting agent, a mildewcide, a biocide, an anti-skinning agent, a coloring agent, an antioxidant, a plasticizer, a leveling agent, an adhesion promoter, and a grinding medium. Based on the weight of the aqueous coating composition, these additives can exist with following total concentration: 0 to 10 wt % and can be 0.1 wt % to 5 wt % or 0.2 wt % to 1 wt %. Based on the weight of the aqueous coating composition, the aqueous coating composition can also include the water of following concentration: 30 wt % to 90 wt % and can be 40 wt % to 80 wt % or 50 wt % to 70 wt %.

[0074] Waterborne coating composition of the present invention can be prepared by mixing component (A) usually in aqueous dispersion, component (B), component (D) and component (E) usually in the aqueous solution with component (C) and optional above-mentioned multifunctional carboxylic acid hydrazide, pigment and other optional components.All components except component (C) such as ATMP in the waterborne coating composition are mixed in any order, finally mix with component (C) subsequently.For example, first emulsion polymer and dicarboxylic acid and / or its salt (preferably in the aqueous solution) are mixed, then mix with other components (if present).Alternatively, component (A) can first be mixed with component (D), component (E) and other optional components (if present), then component (B) can be added, then component (C) (desirably, ATMP) is finally added subsequently.Pigment and / or extender are preferably mixed with dispersant to form the slurry of pigment and / or extender.

[0075] Water-based coating compositions of the present invention can be used for rust conversion. Water-based coating compositions can be applied and adhered to easily corroded substrates such as metal substrates. Metal substrates can include, for example, ferrous metals, such as cast iron, welds, and carbon steel. Water-based coating compositions can be applied directly to substrates, particularly to substrates without pretreatment, such as on rusty metal surfaces. Water-based coating compositions have the ability of rust conversion (even if the rust on the metal surface is converted or reacted), that is, after applying water-based coating compositions of the present invention, the original porous rust on the substrate surface can be converted into a dark purple coordination compound, thereby forming a coating film (i.e., coating) on ​​the substrate, and this coating film will be applied together with the aqueous acrylic coating composition. The coordination compound is insoluble in water and organic solvents.

[0076] Aqueous coating composition of the present invention is particularly suitable for forming the priming coat of multilayer coating, and this multilayer coating also comprises one or more top coats, and these top coats are made by the aqueous top coating composition that is different from above-mentioned aqueous coating composition of the present invention.The application still further relates to a kind of multilayer coating, this multilayer coating comprises the priming coat made by aqueous coating composition of the present invention and the top coating made by aqueous top coating composition, wherein priming coat is between top coating and base material.Base material is as described above.The film thickness of multilayer coating can be 40 microns (μm) to 60 μm. The multi-layer coating may have properties including, for example, the following: (I) flash rust resistance, with a flash rust rating of "0" after exposure to 24 hours at 23°C and 90% relative humidity (RH) according to ISO 8501-4:2006; (II) good early water resistance, as indicated by a blister rating of "8M" or better and desirably "8F" or "10"; (III) good adhesion to the substrate, as indicated by an adhesion classification of "4B" or better and desirably "5B" according to ASTM D 3359; and (IV) good water resistance, as indicated by a blister rating of "8M" or better and desirably "8F" or "10". These properties can be measured according to the test methods described in the Examples section below.

[0077] The aqueous top coating composition that can be used in the present invention can be an acrylic top coating composition containing an acrylic emulsion polymer that can be used as a binder. The acrylic emulsion polymer in the top coating composition can include the above-mentioned emulsion polymer and a commercially available acrylic binder, such as MAINCOTE TM HG-100, MAINCOTE TM HG-300 and PRIMAL TM AS-8508 emulsion polymer, all available from The Dow Chemical Company (MAINCOTE and PRIMAL are trademarks of The Dow Chemical Company). The top coating composition may further comprise one or more of the following components: a pigment, an extender, a defoamer, a thickener, a wetting agent, a coalescing agent, a dispersant, and a polyfunctional carboxylic acid hydrazide containing at least two hydrazide groups per molecule, which components may be those described above. The top coating composition may comprise one or more of the optional additives described above.

[0078] The present invention relates to a method for preparing a coating (desirably, a multilayer coating). The method comprises the following steps: (i) providing an aqueous coating composition of the present invention, (ii) applying the aqueous coating composition directly to a corrosive substrate, and (iii) drying or allowing the applied aqueous coating composition to dry, thereby forming a primer layer on the substrate. When the coating is a multilayer coating, the method may further comprise: (iv) applying an aqueous acrylic top coating composition to the primer layer obtained by step (iii); and (v) drying or allowing the applied aqueous top coating composition to dry to form a top coating layer, such that the primer layer is located between the substrate and the top coating layer. The coating is suitable for marine protective coatings, general industrial finishes, metal protective coatings, automotive coatings, road marking coatings, exterior insulation and decorative systems (EIFS), wood coatings, coil coatings, plastic coatings, can coatings, architectural coatings and civil engineering coatings, and is particularly suitable for metal protective coatings. The substrate used in the method may be an unpretreated substrate. The method may not include a step of pretreating the substrate surface (e.g., by polishing), and the coating obtained by the method still has the above-mentioned characteristics.

[0079] The coating composition (e.g., the aqueous coating composition or aqueous acrylic top coating composition of the present invention) can be applied to the substrate by conventional means, including brushing, dipping, roller coating, and spraying. The aqueous coating composition is preferably applied by spraying. Standard spraying techniques and spraying equipment can be used, such as air atomizing spraying, air spraying, airless spraying, high volume low pressure spraying, and electrostatic spraying (e.g., electrostatic bell application) and manual or automatic methods. After the coating composition is applied to the substrate, the composition can be dried or allowed to dry at a temperature in the range of 0°C to 35°C or at an elevated temperature, such as 35°C to 60°C, to form a coating film (i.e., a primer or top coating).

[0080] Example

[0081] Some embodiments of the present invention will now be described in the following examples, in which all parts and percentages are by weight (wt%), wherein wt% is relative to the weight of the emulsion polymer unless otherwise stated. The materials used in the samples are described below.

[0082]

[0083]

[0084] OROTAN, RETAN, ACRYSOL, MAINCOTE, and PRIMAL are trademarks of The Dow Chemical Company.

[0085] Aqueous polymer dispersions containing the emulsion polymer used as a binder in the rust conversion coating composition samples were prepared according to the following synthetic method:

[0086] Synthesis of aqueous polymer dispersion "PD 40"

[0087] Deionized (DI) water (409 grams (g)), FES 32 surfactant (31%, 55g), ST (892g), BA (683g), AA (33g), PEM (6g), MEUR (50%, 10g), and n-DDM (4g) were mixed together to produce a stable monomer emulsion. FES 32 surfactant (31%, 6g), monomer emulsion (54g), and APS (6g) in DI water (18g) were added to DI water (728g) at 90°C under a nitrogen (N2) atmosphere, followed by the addition of DI water (10g) to form a reaction mixture. The remaining monomer emulsion, APS (2.5g) in DI water (64g), and ammonia (25%, 6g) in DI water (62g) were then added at 88°C over 180 minutes (min), followed by the addition of DI water (25g). At the end of the polymerization, DI water (3 g) containing FeSO (0.01 g) mixed with DI water (3 g) containing sodium salt of EDT A (0.02 g), t-BHP solution (4.9 g) dissolved in DI water (26 g), and DI water solution (45 g) containing IAA (2.3 g) were all added at 60° C., and then DI water (25 g) containing ammonia (53 g) was added at 50° C. to obtain an aqueous dispersion.

[0088] Synthesis of aqueous polymer dispersion "PD 76"

[0089] A stage 1 monomer emulsion (ME1) was prepared by mixing together DI water (288 g), AB / 20 surfactant (28.5%, 29 g), BA (560 g), ST (585 g), PEM (16 g), MAA (30 g), DAAM (31 g), MEUR (50%, 4.3 g), and n-DDM (2.5 g) to produce a stable monomer emulsion. A stage 2 monomer emulsion (ME2) was prepared by mixing together DI water (124 g), AB / 20 surfactant (28.5%, 13 g), BA (105 g), ST (425 g), MEUR (50%, 2 g), and n-DDM (1.1 g) to produce a stable monomer emulsion.

[0090] To a 5-liter, four-necked round-bottom flask equipped with a paddle stirrer, a thermocouple, a nitrogen inlet, and a reflux condenser was added DI water (879 g) and stirring was begun. The contents of the flask were heated to 90° C. under an N2 atmosphere. To the flask were added AB / 20 surfactant (28.5%, 10 g), MAA (5.3 g), ME1 (89 g), and DI water (46 g) containing APS (5.0 g), followed by a DI water (30 g) rinse. The remaining ME1, DI water (45 g) containing APS (1.6 g), and DI water (43 g) containing ammonia (25%, 15 g) were then added over 87 minutes. After the ME1 feed was complete, DI water (30 g) was added as a rinse. ME2 and DI water (20 g) containing APS (0.7 g) were then added over 33 minutes. After the ME2 feed was complete, DI water (30 g) was added as a rinse. During the addition, the contents of the flask were maintained at 87-89° C. At the end of the polymerization, a mixture of DI water (5 g) containing FeSO 4 ·7H 2 O (0.014 g) and DI water (5 g) containing sodium EDTA (0.028 g), a solution of t-BHP (70%, 3.4 g t-BHP dissolved in 36 g DI water), and a solution of IAA (2.3 g IAA dissolved in 38 g DI water) were all added to the flask at 60° C., and then DI water (26 g) containing ammonia (25%, 26 g) and DI water (67 g) containing ADH (19 g) were added to the flask at 50° C. to obtain an aqueous dispersion.

[0091] Synthesis of aqueous polymer dispersion "PD 00"

[0092] A stage 1 monomer emulsion (ME1) was prepared by mixing together DI water (296 g), AB / 20 surfactant (28.5%, 32 g), BA (405 g), ST (685 g), PEM (16 g), MAA (31 g), AAEM (128 g), MEUR (50%, 4.5 g), and n-DDM (2.6 g) to produce a stable monomer emulsion. A stage 2 monomer emulsion (ME2) was prepared by mixing together DI water (127 g), AB / 20 surfactant (28.5%, 14 g), BA (209 g), ST (340 g), MEUR (50%, 1.9 g), and n-DDM (1.1 g) to produce a stable monomer emulsion.

[0093] To a 5-liter, four-necked round-bottom flask equipped with a paddle stirrer, a thermocouple, a nitrogen inlet, and a reflux condenser was added DI water (899 g) and stirring was initiated. The contents of the flask were heated to 90° C. under an N2 atmosphere. To the flask were added AB / 20 surfactant (28.5%, 7.5 g), MAA (5.5 g), ME1 (92 g), and DI water (46 g) containing APS (5.1 g), followed by a DI water (30 g) rinse. The remaining ME1, DI water (45 g) containing APS (1.6 g), and DI water (43 g) containing ammonia (25%, 15 g) were then added over 87 minutes. After the ME1 feed was complete, DI water (30 g) was added as a rinse. ME2 and DI water (20 g) containing APS (0.7 g) were then added over 33 minutes. After the ME2 feed was complete, DI water (30 g) was added as a rinse. During the addition, the contents of the flask were maintained at 87-89° C. At the end of the polymerization, a mixture of DI water (5 g) containing FeSO 4 ·7H 2 O (0.014 g) and DI water (5 g) containing sodium EDTA (0.028 g), a solution of t-BHP (70%, 3.5 g t-BHP dissolved in 36 g DI water), and a solution of IAA (2.4 g IAA dissolved in 38 g DI water) were all added to the flask at 60° C., and then DI water (26 g) containing ammonia (25%, 39 g) was added to the flask at 50° C. to obtain an aqueous dispersion.

[0094] Synthesis of aqueous polymer dispersion "PD 29"

[0095] A stage 1 monomer emulsion (ME1) was prepared by mixing together DI water (301 g), B-11 surfactant (54%, 15 g), BA (560 g), ST (572 g), PEM (26 g), MAA (30 g), DAAM (43 g), MEUR (50%, 4.3 g), and n-DDM (5 g) to produce a stable monomer emulsion. A stage 2 monomer emulsion (ME2) was prepared by mixing together DI water (130 g), B-11 surfactant (54%, 7.6 g), BA (105 g), ST (425 g), MEUR (50%, 2 g), and n-DDM (1.0 g) to produce a stable monomer emulsion.

[0096] To a 5-liter, four-necked round-bottom flask equipped with a paddle stirrer, a thermocouple, a nitrogen inlet, and a reflux condenser was added DI water (780 g) and stirring was begun. The contents of the flask were heated to 90° C. under an N2 atmosphere. To the flask were added B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and DI water (44 g) containing APS (5 g), followed by a rinse with DI water (45 g). The remaining ME1, DI water (71 g) containing APS (1.5 g), and DI water (52 g) containing ammonia (25%, 15 g) were then added over 87 minutes. After the ME1 feed was complete, DI water (30 g) was added as a rinse. ME2 and DI water (30 g) containing APS (0.7 g) were then added over 33 minutes. After the ME2 feed was complete, DI water (30 g) was added as a rinse. During the addition, the contents of the flask were maintained at 87-89° C. At the end of the polymerization, a mixture of DI water (5 g) containing FeSO 4 ·7H 2 O (0.008 g) and DI water (5 g) containing sodium EDTA (0.016 g), a solution of t-BHP (70%, 3.4 g t-BHP dissolved in 43 g DI water), and a solution of IAA (2.3 g IAA dissolved in 78 g DI water) were all added to the flask at 60° C., and then DI water (26 g) containing ammonia (25%, 26 g) and DI water (67 g) containing ADH (26 g) were added to the flask at 50° C. to obtain an aqueous dispersion.

[0097] Synthesis of aqueous polymer dispersion "PD 31"

[0098] A stage 1 monomer emulsion (ME1) was prepared by mixing together DI water (301 g), B-11 surfactant (54%, 15 g), BA (570 g), ST (597 g), PEM (26 g), MAA (30 g), DAAM (9 g), MEUR (50%, 4.3 g), and n-DDM (5 g) to produce a stable monomer emulsion. A stage 2 monomer emulsion (ME2) was prepared by mixing together DI water (130 g), B-11 surfactant (54%, 7.6 g), BA (105 g), ST (425 g), MEUR (50%, 2 g), and n-DDM (1.0 g) to produce a stable monomer emulsion.

[0099] To a 5-liter, four-necked round-bottom flask equipped with a paddle stirrer, a thermocouple, a nitrogen inlet, and a reflux condenser was added DI water (780 g) and stirring was begun. The contents of the flask were heated to 90° C. under an N2 atmosphere. To the flask were added B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and DI water (44 g) containing APS (5 g), followed by a rinse with DI water (45 g). The remaining ME1, DI water (71 g) containing APS (1.5 g), and DI water (52 g) containing ammonia (25%, 15 g) were then added over 87 minutes. After the ME1 feed was complete, DI water (30 g) was added as a rinse. ME2 and DI water (30 g) containing APS (0.7 g) were then added over 33 minutes. After the ME2 feed was complete, DI water (30 g) was added as a rinse. During the addition, the contents of the flask were maintained at 87-89° C. At the end of the polymerization, a mixture of DI water (5 g) containing FeSO 4 ·7H 2 O (0.008 g) and DI water (5 g) containing sodium EDTA (0.016 g), a solution of t-BHP (70%, 3.4 g t-BHP dissolved in 43 g DI water), and a solution of IAA (2.3 g IAA dissolved in 78 g DI water) were all added to the flask at 60° C., and then DI water (26 g) containing ammonia (25%, 26 g) and DI water (14 g) containing ADH (5.3 g) were added to the flask at 50° C. to obtain an aqueous dispersion.

[0100] Synthesis of aqueous polymer dispersion "PD 41"

[0101] A stage 1 monomer emulsion (ME1) was prepared by mixing together DI water (301 g), B-11 surfactant (54%, 15 g), BA (560 g), ST (580 g), PEM (35 g), MAA (26 g), DAAM (31 g), MEUR (50%, 4.3 g), and n-DDM (5 g) to produce a stable monomer emulsion. A stage 2 monomer emulsion (ME2) was prepared by mixing together DI water (130 g), B-11 surfactant (54%, 7.6 g), BA (105 g), ST (425 g), MEUR (50%, 2 g), and n-DDM (1.0 g) to produce a stable monomer emulsion.

[0102] To a 5-liter, four-necked round-bottom flask equipped with a paddle stirrer, a thermocouple, a nitrogen inlet, and a reflux condenser was added DI water (780 g) and stirring was begun. The contents of the flask were heated to 90° C. under an N2 atmosphere. To the flask were added B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and DI water (44 g) containing APS (5 g), followed by a rinse with DI water (45 g). The remaining ME1, DI water (71 g) containing APS (1.5 g), and DI water (52 g) containing ammonia (25%, 15 g) were then added over 87 minutes. After the ME1 feed was complete, DI water (30 g) was added as a rinse. ME2 and DI water (30 g) containing APS (0.7 g) were then added over 33 minutes. After the ME2 feed was complete, DI water (30 g) was added as a rinse. During the addition, the contents of the flask were maintained at 87-89° C. At the end of the polymerization, a mixture of DI water (5 g) containing FeSO 4 ·7H 2 O (0.008 g) and DI water (5 g) containing sodium EDTA (0.016 g), a solution of t-BHP (70%, 3.4 g t-BHP dissolved in 43 g DI water), and a solution of IAA (2.3 g IAA dissolved in 78 g DI water) were all added to the flask at 60° C., and then DI water (26 g) containing ammonia (25%, 26 g) and DI water (48 g) containing ADH (18.5 g) were added to the flask at 50° C. to obtain an aqueous dispersion.

[0103] Synthesis of aqueous polymer dispersion "PD 42"

[0104] A stage 1 monomer emulsion (ME1) was prepared by mixing together DI water (301 g), B-11 surfactant (54%, 15 g), BA (564 g), ST (585 g), PEM (18 g), MAA (35 g), DAAM (31 g), MEUR (50%, 4.3 g), and n-DDM (5 g) to produce a stable monomer emulsion. A stage 2 monomer emulsion (ME2) was prepared by mixing together DI water (130 g), B-11 surfactant (54%, 7.6 g), BA (105 g), ST (425 g), MEUR (50%, 2 g), and n-DDM (1.0 g) to produce a stable monomer emulsion.

[0105] To a 5-liter, four-necked round-bottom flask equipped with a paddle stirrer, a thermocouple, a nitrogen inlet, and a reflux condenser was added DI water (780 g) and stirring was begun. The contents of the flask were heated to 90° C. under an N2 atmosphere. To the flask were added B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and DI water (44 g) containing APS (5 g), followed by a rinse with DI water (45 g). The remaining ME1, DI water (71 g) containing APS (1.5 g), and DI water (52 g) containing ammonia (25%, 15 g) were then added over 87 minutes. After the ME1 feed was complete, DI water (30 g) was added as a rinse. ME2 and DI water (30 g) containing APS (0.7 g) were then added over 33 minutes. After the ME2 feed was complete, DI water (30 g) was added as a rinse. During the addition, the contents of the flask were maintained at 87-89° C. At the end of the polymerization, a mixture of DI water (5 g) containing FeSO 4 ·7H 2 O (0.008 g) and DI water (5 g) containing sodium EDTA (0.016 g), a solution of t-BHP (70%, 3.4 g t-BHP dissolved in 43 g DI water), and a solution of IAA (2.3 g IAA dissolved in 78 g DI water) were all added to the flask at 60° C., and then DI water (26 g) containing ammonia (25%, 26 g) and DI water (48 g) containing ADH (18.5 g) were added to the flask at 50° C. to obtain an aqueous dispersion.

[0106] The polymer dispersions thus prepared were characterized according to the following test methods and the properties are given in Table 1:

[0107] Solid content

[0108] The solids content of the aqueous polymer dispersion was determined by weighing 0.7 ± 0.1 g of sample (the wet weight of the sample was designated "W1"), placing the sample in an aluminum pan in an oven at 150°C for 25 minutes (the weight of the aluminum pan was designated "W2"), then cooling to room temperature and weighing the aluminum pan with the dried sample, with the total weight designated "W3". "W3 - W2" refers to the dry or solid weight of the sample. The solids content was calculated as (W3 - W2) / W1 * 100%.

[0109] GPC analysis

[0110] The number average molecular weight (M) of the emulsion polymer in the aqueous polymer dispersion was determined by GPC analysis, typically performed by an Agilent 1200. nThe sample was dissolved in tetrahydrofuran (THF) / formic acid (FA) (5%) at a concentration of 2 mg / mL, stirred for more than one hour, stored overnight at room temperature, and then filtered through a 0.45 μm polytetrafluoroethylene (PTFE) filter before GPC analysis. GPC analysis was performed under the following conditions:

[0111] Columns: one PLgel GUARD column (10 μm, 50 millimeters (mm) × 7.5 mm), two mixed B columns (7.8 mm × 300 mm) in series; column temperature: 40°C; mobile phase: THF / FA (5%); flow rate: 1.0 ml / min; injection volume: 100 mL; detector: Agilent refractive index detector, 40°C; and calibration curve: PL polystyrene I narrow standards with molecular weights ranging from 2,329,000 g / mol to 580 g / mol, using a polynomial 3 fit.

[0112] Table 1. Properties of aqueous polymer dispersions

[0113] polymer dispersions Fox Tg,℃ pH Solid content, % Particle size, nm Mn, g / mol PD 40 22 7.86 47.88 115 N.A. PD 76 22 6.84 47.36 115 22214 PD 00 22 9.04 47.46 129 NA PD 31 22 7.03 48.39 124 15056 PD 29 22 7.18 47.97 121 18892 PD 42 22 6.99 48.48 122 15774 PD 41 22 7.02 47.84 123 18754

[0114] *Fox Tg of emulsion polymer in polymer dispersion calculated by Fox equation. Particle size measured by Brookhaven BI-90 Plus particle size analyzer. NA - Not Applicable.

[0115] Preparation of dicarboxylic acid solution

[0116] (1) Preparation of an aqueous solution of neutralized sebacic acid ("sebacic acid solution"): Sebacic acid (6.00 g), aqueous ammonia solution (25%, 19.53 g) and water (1.74 g) were mixed and stirred to obtain a clear solution comprising sebacic acid, monoammonium sebacate, diammonium sebacate or a mixture thereof.

[0117] (2) Preparation of an aqueous solution of neutralized succinic acid ("succinic acid solution"): Succinic acid (6.00 g), aqueous ammonia solution (25%, 19.53 g) and water (1.74 g) were mixed and stirred to obtain a clear solution comprising succinic acid, monoammonium succinate, diammonium succinate or a mixture thereof.

[0118] (3) Preparation of an aqueous solution of neutralized adipic acid ("adipic acid solution"): Adipic acid (6.00 g), aqueous ammonia solution (25%, 19.53 g) and water (1.74 g) were mixed and stirred to obtain a clear solution comprising adipic acid, monoammonium adipate, diammonium adipate or a mixture thereof.

[0119] Waterborne acrylic top coating composition

[0120] The formulation of the waterborne acrylic top coating composition is given in Table 2, wherein the amount of each component is reported in grams (g). The pigment grind was prepared by mixing the components using a high-speed grinder at 1500 revolutions per minute (RPM) for 20 minutes. The binder was premixed with water and an aqueous ammonia solution to adjust the pH to above 8.5 to obtain a premix. The pigment grind was then added to the premix, followed by the addition of TEXANOL ester alcohol. An aqueous solution of NaNO2 (flash rust inhibitor) was further added to the resulting mixture. Finally, ACRYSOL RM-8W rheology modifier and water were added to adjust the viscosity of the resulting sample to 80-90 Krebs units (KU), such as by using a BROOKFIELD TM The viscosity was measured with a KU-3 viscometer at room temperature, thereby forming a waterborne acrylic top coating composition.

[0121] Table 2. Waterborne acrylic top coating compositions

[0122]

[0123] Rust conversion coating composition samples

[0124] The formulations for direct-to-metal (DTM) rust conversion coating compositions are given in Tables 3 and 4, with the amount of each component reported in grams (g). To prepare the compositions of IE 1-11 given in Table 3, tannic acid was dissolved in a mixture of ethanol and water, followed by the addition of isopropyl alcohol. To the resulting solution, the aqueous polymer dispersion prepared above (as a binder) was added, followed by the addition of TEX ANOL ester alcohol. The sodium silicate solution and the dicarboxylic acid solution prepared above were then added sequentially. ATMP solution was further added to the resulting mixture, followed by an aqueous ammonia solution to adjust the pH to above 7.0. Finally, the resulting composition was filtered through a 325 mesh (45 μm) sieve to separate the gel (if any). Compositions for CE 1-18 were prepared essentially the same as above, except that some components were omitted or differed, as given in Table 4. All resulting rust conversion coating composition samples were evaluated according to the following test methods, and the properties and characterization results are given in Tables 3 and 4:

[0125] Preparation of coated panels

[0126] First, the sandblasted steel panel (from Guangdong Honghong Industrial Co., Ltd.) TMStandard test panels (based on the Q-FOG / CCT1100 model) were exposed to a salt spray environment (5% sodium chloride fog in a Q-Fog cyclic corrosion tester) for 24 hours to induce rust on the panel surface. The rusted panels were then washed with DI water to clean the salt from the surface. After drying, the panels were sanded with 240-grit sandpaper to remove loose rust on the panel surface. However, tightly adhered rust was not removed and remained on the panel surface. The panel surface was further treated with alcohol to remove the anti-rust oil.

[0127] The rust conversion coating composition samples (1.5 g) listed in Tables 3 and 4 were brushed onto the obtained panels using an artist's brush (Model 6713 from Shanghai Oil Paint Brush Manufactory). A second layer of the rust conversion coating composition sample was then brushed on 2 hours after the first layer was applied. When the panels were left under ambient conditions (23° C. and 50% RH) for 48 hours, the surface of the coated panels gradually turned dark black-purple. Then, a sample (1.5 g) of the waterborne acrylic top coating composition prepared as listed in Table 2 was further brushed onto the panels using an artist's brush (from the same source as above), which gave the resulting coated panels a final dry film thickness of 18 μm to 20 μm. The coated panels thus prepared (hereinafter referred to as “coated panels”) were then characterized according to the following test methods:

[0128] Flash rust resistance test

[0129] The coated panels prepared above were immediately placed in an environmental chamber (23°C and 90% RH) for 24 hours. The coated panels were then removed and evaluated for flash rust according to ISO 8501-4:2006, as shown in Table A and the following rust ratings. An acceptable flash rust rating is "0".

[0130] Table A: Description of surface appearance of four flash rust grades

[0131]

[0132]

[0133] Rust grades can include the degree of rust, where "S" means spot, "G" means full-face, and "P" means pinpoint; and are rated as a percentage of surface rust, where "10" means less than or equal to 0.01%, "9" means greater than 0.01% and up to 0.03%, "8" means greater than 0.03% and up to 0.1%, "7" means greater than 0.1% and up to 0.3%, "6" means greater than 0.3% and up to 1.0%, "5" means greater than 1.0% and up to 3.0%, "4" means greater than 3.0% and up to 10.0%, "3" means greater than 10.0% and up to 16.0%, "2" means greater than 16.0% and up to 33.0%, "1" means greater than 33.0% and up to 50.0%, and "0" means greater than 50.0%. An acceptable rust grade is "10."

[0134] Early water resistance testing

[0135] The coated panels prepared above were dried at 23°C and 50% RH for 2 hours and then partially immersed in DI water at 23°C for 1 day. The surface of the panels after immersion was then visually observed and then subjected to a blister rating according to ASTM D714-02 (2009), which includes numbers and / or one or more letters, as shown in Table B. The letters F, M, MD, or D are qualitative indications of the density of blistering. The numbers refer to the size of the blister, with 2 being the largest size, 8 being the smallest size, and 10 being no blistering. The larger the number, the smaller the size of the blister. Panels with a blister rating of "8M" or better (desirably, "8F" or "10") are acceptable, indicating good early water resistance.

[0136] Table B: Blister Rating Criteria

[0137] Density of foam abbreviation Bubble size Rating rare F Very large bubbles 2 medium M Big bubbles 4 Medium density MD Small to medium bubbles 6 dense D Minimal blistering visible to the naked eye 8 No foaming 10

[0138] Water resistance test

[0139] The coated panels prepared above were dried at 23°C and 50% RH for 7 days and then partially immersed in DI water at 23°C for 1 day. The surface of the panel after immersion was then visually observed and blister rating was performed according to the same procedure and criteria as described above in the early water resistance test. Panels with a blister rating of "8M" or better (desirably, "8F" or "10") were acceptable, indicating good water resistance.

[0140] Adhesion test

[0141] The coated panels prepared above were dried at 23°C and 50% RH for 7 days and then evaluated for adhesion properties according to ASTM D 3359. Panels classified as "4B" or better (desirably, "5B") were acceptable, indicating good adhesion to the steel panel surface.

[0142] The properties and characterization of the coated panels are given in Tables 3 and 4. As shown in Table 3, the IE 1-11 rust conversion coating samples, each comprising a multi-stage emulsion polymer binder containing specific levels of structural units of PEM and DAAM in combination with specific concentrations of sebacic acid, tannic acid, sodium silicate, and ATMP (after rust conversion), provided a significantly improved synergistic effect on the properties of the coatings comprising different waterborne acrylic topcoats, including flash rust resistance, early water resistance, water resistance, and adhesion properties.

[0143] In contrast, rust-converting coating composition samples that did not contain any one or more of the claimed components and / or were outside the claimed scope failed to meet one or more of the aforementioned property requirements after rust conversion. Substituting equal amounts of succinic acid or adipic acid for sebacic acid (CE 2 and 3) resulted in significantly reduced flash rust resistance and adhesion compared to IE 1. The flash rust resistance of CE 2 and 3 was even worse than that of the sample without the added dicarboxylic acid (CE 1). In the absence of ATMP, sample CE 5 exhibited impaired flash rust resistance and significantly reduced adhesion. In the absence of silicate (CE 6), tannic acid (CE 7), or both ATMP and silicate (CE 9), all properties of these samples were significantly impaired. Substituting phosphorous acid for ATMP resulted in slightly worse flash rust resistance and early water resistance (CE 12). Even in the presence of sebacic acid (CE 8), the use of binder PD 76 alone without the combination of tannic acid, sodium silicate, and ATMP resulted in poor flash rust resistance and adhesion. Sample CE 10, which had a silicate / ATMP ratio of 1.0, showed reduced flash rust resistance and poor adhesion properties, while sample CE 18, which had a silicate / ATMP ratio of 4, suffered from compromised early water resistance. When AAEM was used instead of DAAM to prepare the binder in the rust conversion coating (CE 11), although flash rust resistance was maintained, early water resistance and adhesion properties were compromised, indicating that early water resistance and adhesion properties are not necessarily correlated with flash rust resistance. Sample CE 4, which contained the acrylic binder PD40 and post-added ADH in the basecoat, showed no significant improvement in flash rust resistance, but slightly improved adhesion properties. Sample CE 13, which used an emulsion polymer containing 0.5 wt. % DAAM structural units in the rust conversion coating, showed unsatisfactory flash rust resistance and adhesion properties. Sample CE 14, which contained 4.0 wt. % sebacic acid in the rust conversion coating, showed poor adhesion and early water resistance properties. Samples CE 15 and 16, which used too low or too high a tannic acid loading (30 wt% and 70 wt% based on dry polymer, respectively) in the rust conversion coating, failed to meet all requirements for flash rust resistance, adhesion, and early water resistance. CE 17 shows that too low an ATMP loading (20 wt%) in the rust conversion coating resulted in poor flash rust resistance and adhesion properties. Furthermore, the tannic acid to ATMP ratios in both CE 16 and 17 samples were higher than 1.75 (1.97 and 2.42, respectively).

[0144]

[0145]

Claims

1. A water-based coating composition, comprising: (A) an emulsion polymer comprising: (i) 0.48% to 1.5% by weight of structural units of ethylenically unsaturated phosphorus-containing monomers, (ii) 0.7 to 3% by weight of structural units of diacetone (meth)acrylamide, (iii) 10% to 80% by weight of structural units of vinyl aromatic monomers, (iv) Structural units of alkyl (meth)acrylate and (v) 0 to 5% by weight of structural units of α,β-ethylenically unsaturated carboxylic acids, salts thereof, or mixtures thereof; (B) a dicarboxylic acid, a salt thereof, or a mixture thereof; wherein the dicarboxylic acid has the structure of formula (I): HOOC-R-COOH wherein R is an alkylene, alkenylene, alkynylene, cycloalkylene, cycloalkenylene, cycloalkynylene, arylene, or heteroarylene group containing 6 to 18 carbon atoms; and wherein (B) the dicarboxylic acid, salt thereof, or mixture thereof is present in an amount to provide a concentration of -OOC-R-COO- segments of 1.1 wt% to 3.8 wt%; (C) 30% to 60% by weight of a thio, amide or imido derivative of a triphosphonic acid, a salt thereof or a mixture thereof; (D) a water-soluble alkali metal silicate, said water-soluble alkali metal silicate being present in an amount to provide a dry weight ratio of (D) said water-soluble alkali metal silicate to (C) said thio-, amido-, or imide derivative of a triphosphonic acid, a salt thereof, or a mixture thereof, in the range of 1.2 to 3.7; and (E) 40% to 52% by weight of tannic acid, gallic acid, pyrogallol, or citric acid; a salt thereof; or a combination thereof; The weight percentages are relative to the weight of the emulsion polymer.

2. The aqueous coating composition according to claim 1, wherein the dicarboxylic acid is selected from the group consisting of sebacic acid, dodecanedioic acid, suberic acid, azelaic acid, undecanedioic acid, eicosanedioic acid, and mixtures thereof.

3. The aqueous coating composition according to claim 1, wherein the thio, amide or imide derivative of the triphosphonic acid of component (C), a salt thereof or a mixture thereof is selected from aminotrimethylenephosphonic acid and aminotriethylenephosphonic acid; salts thereof; and combinations thereof.

4. The aqueous coating composition according to claim 1 or 2, wherein component (E) is tannic acid.

5. The aqueous coating composition according to claim 1 or 2, wherein the ethylenically unsaturated phosphorus-containing monomer is selected from phosphoethyl methacrylate, phosphoethyl acrylate, allyl ether phosphate, phosphopropyl methacrylate, phosphobutyl methacrylate and mixtures thereof.

6. The aqueous coating composition according to claim 1 or 2, wherein the glass transition temperature of the emulsion polymer is from -10°C to 50°C, as calculated by the Fox equation.

7. The aqueous coating composition of claim 1 or 2, wherein the emulsion polymer has a number average molecular weight of 8,000 to 60,000 g / mol, as measured by gel permeation chromatography.

8. The aqueous coating composition of claim 1 or 2, wherein the emulsion polymer is a multistage polymer comprising from 50% to 90% by weight of polymer A and from 10% to 50% by weight of polymer B, based on the weight of the multistage polymer; wherein, based on the weight of the polymer A, the polymer A comprises 0.3 wt % to 2.4 wt % of structural units of the ethylenically unsaturated phosphorus-containing monomer, 1 wt % to 6 wt % of structural units of the diacetone (meth) acrylamide, and 10 wt % to 75 wt % of structural units of the vinyl aromatic monomer; wherein, based on the weight of polymer B, polymer B comprises 0 to 2.5 wt % of structural units of the ethylenically unsaturated phosphorus-containing monomer, 0 to 2.5 wt % of structural units of diacetone (meth) acrylamide, and 10 to 100 wt % of structural units of the vinyl aromatic monomer; and At least one of the polymer A and the polymer B further comprises a structural unit of the alkyl (meth)acrylate.

9. The aqueous coating composition according to claim 1 or 2, further comprising a polyfunctional carboxylic hydrazide containing at least two hydrazide groups per molecule.

10. A method for preparing a coating, the method comprising: (i) providing an aqueous coating composition according to any one of claims 1 to 9; (ii) applying the aqueous coating composition directly onto a corrosion-prone substrate; as well as (iii) drying or allowing to dry the applied aqueous coating composition to form a primer layer on the substrate; and optionally, (iv) applying an aqueous top coating composition comprising an acrylic emulsion polymer to the base coating obtained from step (iii); and (v) drying or allowing to dry the applied aqueous top coating composition to form a top coating, such that the base coating is located between the substrate and the top coating.

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