Aqueous coating compositions and methods for preparing coatings

Abstract

An aqueous coating composition comprising: (A) an emulsion polymer comprising: (i) 0.48 wt % to 1.5 wt % structural units of an ethylenically unsaturated phosphorus-containing monomer; (ii) 0.7 wt % to 3 wt % structural units of diacetone (meth)acrylamide; (iii) 10 wt % to 80 wt % structural units of a vinyl aromatic monomer; (iv) structural units of an alkyl (meth)acrylate; and (v) zero to 5 wt % structural units of an α,β-ethylenically unsaturated carboxylic acid, its salt, or a mixture thereof; and (B) a specific concentration of a specific dicarboxylic acid. and (C) 30% to 60% by weight of a thio-, amido-, or imido-derivative of triphosphonic acid, its salt, or a mixture thereof, (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) to (C) of 1.2 to 3.7, and (E) 40% to 52% by weight of tannic acid, gallic acid, pyrogallol, or citric acid, their salts, or combinations thereof, wherein the weight percentages are based on the emulsion polymer weight. A method for preparing a coating comprising a basecoat made from the aqueous coating composition.

Description

[Technical Field]

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

[0002] (Introduction) Solvent-based coating compositions containing epoxy resins, polyurethanes, or alkyd resins are widely used for metal protective coatings due to their corrosion resistance, mechanical properties, and appearance. Water-based coating compositions containing acrylic polymers pose far fewer environmental concerns than solvent-based coating compositions. However, flash rust tends to form on metal surfaces as discrete rust spots visible to the naked eye (known as "flash rust") immediately or shortly after application of a water-based coating composition to a corrosion-prone substrate (such as a metal substrate) and before the composition has completely dried. Efforts have been made to develop water-based coating compositions with improved flash rust resistance. While the addition of a sufficient amount of a flash rust inhibitor, such as sodium nitrite, to a water-based coating composition can reduce or eliminate the formation of flash rust on metal surfaces, this usually impairs the initial water-resistant properties of the coating produced therefrom. Furthermore, known water-based coating compositions from the prior art typically lack sufficient adhesion to unprepared metal substrates, such as rusted metal surfaces, once dry. Therefore, metal surfaces usually need to be pretreated to ensure sufficient adhesion between the coating and the substrate, for example, by polishing the metal surface to remove rust or by applying a rust conversion paint over 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 stable, insoluble coordination compounds on the metal surface. Such coordination compounds, which act as basecoats onto which a water-based topcoat composition can be further applied, may help improve corrosion resistance, but offer no benefit in improving the flash rust resistance properties of coatings made therefrom. These acidic rust conversion paints are usually not compatible with most water-based acrylic polymers, which are more stable under basic conditions, and the coordination compound film is still not dense enough, so the coating still exhibits poor adhesion to the metal substrate.

[0003] Thus, there remains a need to provide an aqueous coating composition that can be applied directly onto a corrosion-prone substrate while providing coatings made therefrom that have desirable flash rust resistance, initial water resistance, and adhesion properties. Summary of the Invention

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

[0005] In a first aspect, the present invention provides an aqueous coating composition comprising: (A) an emulsion polymer comprising: (i) 0.48% to 1.5% by weight of structural units of an ethylenically unsaturated phosphorus-containing monomer; (ii) 0.7% to 3% by weight of structural units of diacetone (meth)acrylamide; (iii) 10% to 80% by weight of structural units of a vinyl aromatic monomer; (iv) structural units of an alkyl (meth)acrylate; and (v) zero to 5% by weight of structural units of an α,β-ethylenically unsaturated carboxylic acid, its salt, or a mixture thereof; (B) a dicarboxylic acid, a salt thereof, or a mixture thereof, wherein the dicarboxylic acid is represented by formula (I): HOOC-R-COOH, wherein R is alkylene, alkenylene, alkynylene, cycloalkylene, cycloalkenylene, cycloalkynylene, arylene, or heterocyclic arylene and contains 6 to 18 carbon atoms, and (B) a dicarboxylic acid, salt thereof, or mixture thereof is present in an amount to provide an —OOC—R—COO— segment at a concentration of 1.1 wt % to 3.8 wt %; (C) 30% to 60% by weight of a thio-, amido-, or imido-derivative of triphosphonic acid, its salt, or a mixture thereof; (D) a water-soluble alkali metal silicate, present in an amount to provide a dry weight ratio of the (D) water-soluble alkali metal silicate to (C) a thio-, amido-, or imido-derivative of triphosphonic acid, a salt thereof, or a mixture thereof of from 1.2 to 3.7; (E) 40% by weight to 52% by weight of tannic acid, gallic acid, pyrogallol, or citric acid, a salt thereof, or a combination thereof; It is an aqueous coating composition in which the weight percentages are based on the emulsion polymer weight.

[0006] In a second aspect, the present invention provides a method for preparing a coating, comprising the steps of: (i) providing an aqueous coating composition of the first aspect; (ii) applying the aqueous coating composition directly onto the corrosion-prone substrate; (iii) drying or allowing the applied aqueous coating composition to dry, thereby forming a base coat on the substrate; and optionally (iv) applying to the base coat resulting from step (iii) an aqueous top coating composition comprising an acrylic emulsion polymer; and (v) drying or allowing to dry the applied aqueous top coating composition to form the top coat, such that the base coat is between the substrate and the top coat. DETAILED DESCRIPTION OF THE INVENTION

[0007] Test methods, unless a date is given with the test method number, refer to the test method most recent as of the priority date of this document. Reference to a test method includes both a reference to the testing society and the test method number. The following test method abbreviations and identifiers apply herein: ASTM refers to ASTM International methods, ISO refers to International Organization for Standardization standards, and GB / T refers to Chinese national standards. Products identified by trade names refer to compositions available under those trade names as of the priority date of this document. "And / or" means "and, or as an alternative." All ranges are inclusive unless otherwise indicated.

[0008] Both "untreated surface" and "unpretreated substrate" refer to a substrate surface that is used completely without pretreatment or that has been cleaned to remove dust, loose rust, contaminants, and grease prior to application of the aqueous coating composition of the present invention. Such cleaning is accomplished, for example, only by evaporating the solvent and / or by polishing to remove loose rust. There is no additional treatment or priming of the substrate surface with a rust conversion composition (other than the aqueous coating composition of the present invention) prior to application of the aqueous coating composition of the present invention. "Loose rust" means rust that can be peeled off by hand without the aid of a tool.

[0009] As used herein, an "aqueous" composition or dispersion means that the particles are dispersed in an aqueous medium. By "aqueous medium" herein is meant water and 0-30% 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 a mixture thereof.

[0010] As used herein, "acrylic polymer" refers to a homopolymer of an acrylic monomer or a copolymer containing 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 modified forms thereof, such as hydroxyalkyl (meth)acrylates. Throughout this document, the fragment "(meth)acrylic" refers to both "methacrylic" and "acrylic." 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. The acrylic polymer may include an acrylic homopolymer, a styrene-acrylic copolymer, or a mixture thereof.

[0011] A "structural unit," also known as a "polymerized unit," of a specified monomer refers to the remainder of the monomer after polymerization, i.e., the polymerized monomer or the polymerized form of the monomer. For example, the structural unit of methyl methacrylate is illustrated below:

[0012] [ka] In the formula, the dotted lines represent the points of attachment of the structural units to the polymer backbone.

[0013] "Alkylene" refers to a branched or unbranched, saturated divalent hydrocarbon group. Exemplary alkylene groups include methylene (-CH-), ethylene (-CHCH-), -CHCH(CH)CH-, or combinations thereof. "Cycloalkylene" refers to a branched or unbranched divalent hydrocarbon group connected to one or more cycloalkyl groups. Exemplary cycloalkylene groups include cyclohexylene, methylcyclohexylene, or combinations thereof. "Alkenylene" refers to a branched or unbranched divalent hydrocarbon group having one or more carbon-carbon double bonds. Exemplary alkenylene groups include ethenylene (-CH=CH-), -CH=CH-CH-, -CH=C(CH)-, or combinations thereof. "Cycloalkenylene" refers to a branched or unbranched divalent hydrocarbon group connected to one or more cycloalkyl groups or having one or more carbon-carbon double bonds therein. Exemplary cycloalkenylene groups include cyclohexenylene, -CH=CH-CH 10 -, or combinations thereof. "Alkynylene" means a branched or unbranched divalent hydrocarbon group having one or more carbon-carbon triple bonds. Exemplary alkynylene groups include ethynylene,

[0014] [ka] or combinations thereof. "Cycloalkynylene" means a branched or unbranched divalent hydrocarbon group having one or more cycloalkyl groups attached thereto or having one or more carbon-carbon triple bonds therein. Exemplary cycloalkynylene groups include:

[0015] [ka] or combinations thereof. "Arylene" refers to a branched or unbranched divalent hydrocarbon group connected to one or more aryl groups. Exemplary arylene groups include phenylene, -CH-, -CH-, -CH(CH)-, or combinations thereof. "Heterocyclic arylene" refers to a branched or unbranched divalent hydrocarbon group connected to one or more heterocyclic aryl groups. Exemplary heterocyclic arylene groups include pyridylene, thiazylene, or combinations thereof.

[0016] As used herein, "glass transition temperature" or "T g can be calculated using the following Fox formula (T.G. Fox, Bull. Am. Phys. Soc., Volume 1, Issue No. 3, page 123 (1956)). For example, the T g To calculate

[0017]

number

[0018] "Weight of emulsion polymer" refers to the dry weight of the emulsion polymer.

[0019] The aqueous coating compositions of the present invention typically comprise one or more emulsion polymers (component (A)) in aqueous dispersion. The emulsion polymer comprises structural units of one or more ethylenically unsaturated phosphorus-containing monomers (monomer (i)). The ethylenically unsaturated phosphorus-containing monomers can be dihydrogen phosphate esters of alcohols where the alcohol contains or is substituted with a polymerizable vinyl or olefinic group. Ethylenically unsaturated phosphorus-containing monomers include phosphoalkyl(meth)acrylates such as phosphoethyl(meth)acrylate, phosphopropyl(meth)acrylate, phosphobutyl(meth)acrylate, salts thereof, and mixtures thereof; CH═C(R p1 )-C(O)-O-(R p2 O) q -P(O)(OH)2 (wherein, R p1 =H or CH3, R p2= alkylene (e.g., ethylene group, propylene group, or a combination thereof), q = 1 to 20, such as SIPOMER PAM-100, SIPOMER PAM-200, SIPOMER PAM-300, and SIPOMER PAM-600 (all available from Solvay); phosphoalkoxy(meth)acrylates 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, salts thereof, or mixtures thereof. Desirably, the phosphorous 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 the monomeric structural unit (i) ethylenically unsaturated phosphorus-containing monomer in a concentration of from 0.48 wt.% to 1.5 wt.%, based on the weight of the emulsion polymer, including 0.48 wt.% or more, 0.50 wt.% or more, 0.52 wt.% or more, 0.55 wt.% or more, 0.58 wt.% or more, 0.60 wt.% or more, 0.62 wt.% or more, 0.65 wt.% or more, 0.68 wt.% or more, 0.70 wt.% or more, 0.72 wt.% or more, 0.75 wt.% or more, 0.78 wt.% or more, 0.80 wt.% or more, 0.82 wt.% or more, 0.85 wt.% or more, 0.88 wt.% or more, and While the total content of the cellulose acetate ester may be 0.90% by weight or more, it is generally 1.5% by weight or less, and may be 1.4% by weight or less, 1.3% by weight or less, 1.20% by weight or less, 1.19% by weight or less, 1.18% by weight or less, 1.17% by weight or less, 1.16% by weight or less, 1.15% by weight or less, 1.12% by weight or less, 1.10% by weight or less, 1.08% by weight or less, 1.05% by weight or less, 1.02% by weight or less, 1.00% by weight or less, 0.98% by weight or less, 0.95% by weight or less, or even 0.92% by weight or less, desirably 0.63% by weight to 1.2% by weight, or 0.8% by weight to 1.2% by weight.

[0020] Emulsion polymers useful in the present invention may include structural units (monomer (ii)) of diacetone (meth)acrylamide, desirably diacetone acrylamide (DAAM). The emulsion polymer may include structural units (ii) of diacetone (meth)acrylamide at a concentration of 0.7% to 3% by weight, based on the weight of the emulsion polymer, including 0.7% by weight or more, 0.75% by weight or more, 0.8% by weight or more, 0.9% by weight or more, 1.0% by weight or more, 1.1% by weight or more, 1.2% by weight or more, 1.3% by weight or more, 1.4% by weight or more, 1.5% by weight or more, 1.6% by weight or more, 1.7% by weight or more, and even 1.75% by weight or more. While the amount may be 1.75% or more, at the same time, the concentration is generally 3% or less by weight, and may be 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.45% or less, 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 1.75% or less by weight, desirably 1.75% to 2.45% by weight or 1.1% to 2.1% by weight.

[0021] The emulsion polymer useful in the present invention may comprise one or more vinyl aromatic monomer structural units (monomer (iii)). Suitable vinyl aromatic monomers may include, for example, styrene and substituted styrenes such as α-methylstyrene, p-methylstyrene, t-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 the monomeric structural unit (iii) vinyl aromatic monomer in a concentration of 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 by weight, while generally at a concentration of 80% or less, and may be 75% or less, 70% or less, 65% or less, or even 60% or less by weight, desirably 40% to 65% by weight.

[0022] The emulsion polymers useful in the present invention may contain one or more alkyl(meth)acrylate structural units (monomer (iv)) containing an alkyl having 1 to 24 carbon atoms, other than monomer (i) above. The alkyl(meth)acrylate may have 1 to 20 carbon atoms, 4 to 10 carbon atoms, or 4 to 8 carbon atoms. The alkyl group may be linear, branched, or cyclic alkyl, desirably linear or branched alkyl. 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)methacrylate, 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, t-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 alkyl (meth)acrylate structural units can range from 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 by weight, based on the weight of the emulsion polymer, while generally at a concentration of 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, or even 40% or less by weight, desirably 30% to 55% by weight. Desirably, the emulsion polymer may or may not contain cycloalkyl (meth)acrylate structural units.The concentration of cycloalkyl (meth)acrylate structural units in the emulsion polymer can range from zero to 5% by weight, based on the weight of the emulsion polymer, but can also be less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or even zero.

[0023] The emulsion polymers useful in the present invention may or may not contain structural units (monomer (v)) of one or more α,β-ethylenically unsaturated carboxylic acids, their salts, or mixtures thereof. Suitable α,β-ethylenically unsaturated carboxylic acids may include 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 having acid-forming groups that generate or can be subsequently converted into 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 the monomeric structural unit (v) α,β-ethylenically unsaturated carboxylic acid and salts thereof in a concentration of zero to 5 wt %, and may be 0 wt % or more, 0.3 wt % or more, 0.5 wt % or more, 0.8 wt % or more, 1.0 wt % or more, 1.2 wt % or more, 1.5 wt % or more, 1.8 wt % or more, or even 2 wt % or more, while generally at a concentration of 5 wt % or less, 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, desirably 0.3 wt % to 4 wt % or 1.75 wt % to 2.5 wt %, based on the weight of the emulsion polymer.

[0024] The emulsion polymers useful in the present invention may or may not contain structural units of one or more monoethylenically unsaturated functional monomers other than the monomers (i)-(v) described above, having one or more functional groups selected from amide, silane, hydroxyl, ureido, imide, glycidyl, amino, and sulfonic acid, salts thereof, or combinations thereof (monomer (vi)).These monoethylenically unsaturated functional monomers include, for example, amino-functional monomers such as dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylate, or mixtures thereof; monomers having an amide functional group such as acrylamide and methacrylamide; monomers having a glycidyl functional group such as glycidyl acrylate, glycidyl methacrylate, or mixtures thereof; vinyltrialkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, vinyldimethylethoxysilane, vinylmethyldiethoxysilane, or mixtures thereof; (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltrimethoxysilane, (meth)acryloxyethyltriethoxy ... (meth)acryloxyalkyltrialkoxysilanes such as 2-acryloxypropyltrimethoxysilane, or mixtures thereof; ureido-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 a cyclic ureido group (i.e., an imidazolidin-2-one group), including cyclic ureido-group-containing alkyl esters of (meth)acrylic acid such as N-(2-methacrylamidoethyl)ethyleneurea, N-(2-methacryloyloxyethyl)ethyleneurea, N-(diethylmaleate)ethyleneurea, or mixtures thereof; sodium vinyl sulfonate (sodium Sulfonic acid monomers may be mentioned, 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 include the monomeric structural unit (vi) monoethylenically unsaturated functional monomer in a concentration of zero to 5 wt. %, and may be zero or more, 0.05 wt. % or more, 0.1 wt. % or more, 0.2 wt. % or more, 0.3 wt. % or more, 0.4 wt. % or more, or even 0.5 wt. % or more, while generally at a concentration of 5 wt. % or less, and may 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, desirably 0.1 wt. % to 1 wt. % based on the weight of the emulsion polymer.

[0025] The emulsion polymers useful in the present invention may or may not contain structural units of one or more multi-ethylenically unsaturated monomers (monomer (vii)). Examples of suitable multi-ethylenically 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 monomeric structural unit (vii) multi-ethylenically unsaturated monomer at a concentration of zero to 1 wt. % based on the weight of the emulsion polymer, and may be 0.05 wt. % or more, 0.1 wt. % or more, or even 0.15 wt. % or more, while generally at a concentration of 1 wt. % or less, and may be 1 wt. % or less, 0.8 wt. % or less, 0.5 wt. % or less, 0.4 wt. % or less, or even 0.3 wt. % or less.

[0026] The emulsion polymers useful in the present invention may or may not contain structural units (monomer (viii)) of one or more monoethylenically unsaturated benzophenones, monoethylenically unsaturated acetophenones, or mixtures thereof. Suitable monoethylenically unsaturated benzophenones can include, for example, vinylbenzophenone, (2-hydroxy-3-methacryloxy)propyl ortho-benzoyl-benzoate, (2-hydroxy-3-acryloxy)propyl ortho-benzoyl-benzoate, or mixtures thereof. The monomeric structural unit (viii), monoethylenically unsaturated benzophenone, monoethylenically unsaturated acetophenone, or mixtures thereof, may be present in a total concentration of zero to 3 wt. %, and may be zero or more, 0.1 wt. % or more, 0.3 wt. % or more, 0.5 wt. % or more, or even 0.7 wt. % or more, while generally at a concentration of 3.0 wt. % or less, 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, desirably zero to 1 wt. %, based on the weight of the emulsion polymer.

[0027] Desirably, the emulsion polymers useful in the present invention contain, by weight of the emulsion polymer, 0.8% to 1.2% structural units of phosphoethyl methacrylate, 1.1% to 2.1% structural units of diacetone acrylamide, 40% to 65% structural units of styrene, 30% to 55% structural units of butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, or mixtures thereof, and 0.3% to 4% structural units of acrylic acid, methacrylic acid, or mixtures thereof.

[0028] An emulsion polymer can be a single-stage polymer or a multi-stage polymer. Desirably, the emulsion polymer is a multi-stage polymer, such as a two-stage polymer comprising polymer A and polymer B. As used herein, "single-stage polymer" refers to an emulsion polymer prepared by single-stage emulsion polymerization. As used herein, "multi-stage polymer" refers to an emulsion polymer prepared by multi-stage emulsion polymerization in which two or more different monomer compositions are added sequentially in different stages, such as a first stage and a second stage, thereby forming at least polymer A and polymer B. "Polymer A" and "polymer B" refer to polymers having different compositions and formed in different stages of the multi-stage emulsion polymerization; desirably, polymer A is in the first stage and polymer B is in the second stage of the multi-stage emulsion polymerization. Each stage is polymerized sequentially and differs from the immediately preceding and / or following stage in terms of the difference in monomer composition. Without being bound by theory, a multi-stage polymer may comprise multiple distinct phases or layers, which may be evidenced by at least two Tg's measured by scanning transmission electron microscope (STEM) or by differential scanning calorimetry (DSC). Desirably, polymer A is the outer layer of the multi-stage polymer and polymer B is the inner layer. The multi-stage polymer may consist of polymer A and polymer B. The type and concentration of structural units of the monomers described above for the emulsion polymer section may be selected in polymer A and / or polymer B to provide for the production of a multi-stage polymer (i.e., emulsion polymer) with the Tg value described above for the emulsion polymer section. Desirably, polymer A has a Tg of less than 20°C, and can be 17°C or less, 14°C or less, 11°C or less, or even 8°C or less, while at the same time generally being -20°C or greater, -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.Polymer B may have a Tg greater than 30° C., and may be 35° C. or greater, 40° C. or greater, 45° C. or greater, 49° C. or greater, or even 52° C. or greater, while at the same time generally being less than 80° C., and may be 75° C. or less, 70° C. or less, 65° C. or less, 60° C. or less, 57° C. or less, or even 54° C. The Tg value is calculated according to the Fox equation.

[0029] When the emulsion polymer is a multistage polymer, the monomeric structural units described above in the emulsion polymer section may be present in one or both of polymer A and polymer B at a certain concentration, such that the total concentration of each monomeric structural unit relative to the weight of the multistage polymer (i.e., the emulsion polymer weight) is the same as the weight concentration of such monomeric structural unit relative to the emulsion polymer described above. For example, one or both of polymer A and polymer B in the multistage polymer may contain monomeric structural unit (iv) alkyl (meth)acrylate. Polymer A and / or polymer B, preferably polymer A, may or may not contain monomeric structural unit (v) α,β-ethylenically unsaturated carboxylic acid, its salt, or a mixture thereof. For example, polymer A may contain 1% to 7% by weight of monomeric structural unit (v), based on the weight of polymer A, and polymer B may contain zero to 3% by weight of monomeric structural unit (v), based on the weight of polymer B. Polymer A and / or Polymer B may or may not contain structural units of one or more of the above-described monomers (vi), (vii), and (viii). Desirably, the multi-stage polymer comprises, based on the weight of the multi-stage polymer (i.e., emulsion polymer weight), 50% to 90% by weight of Polymer A and 10% to 50% by weight of Polymer B, wherein Polymer A contains, based on the weight of Polymer A, 0.3% to 2.4% by weight of the monomeric structural unit (i) an ethylenically unsaturated phosphorus-containing monomer, 1% to 6% by weight of the monomeric structural unit (ii) diacetone (meth)acrylamide, and 10% to 75% by weight of the monomeric structural unit (iii) vinyl. and an aromatic monomer, wherein Polymer B comprises, based on the weight of Polymer B, zero to 2.5 wt % of the monomeric structural unit (i) an ethylenically unsaturated phosphorus-containing monomer, zero to 2.5 wt % of the monomeric structural unit (ii) diacetone (meth)acrylamide, and 10 wt % to 100 wt % of the monomeric structural unit (iii) a vinyl aromatic monomer, and at least one (desirably both) of Polymer A and Polymer B further comprises the monomeric structural unit (iv) alkyl (meth)acrylate.All monomers (i)-(v) are as described above in the emulsion polymer section.

[0030] One or both of polymer A and polymer B (desirably polymer A) in the multi-stage polymer may comprise structural units of an ethylenically unsaturated phosphorus-containing monomer. Polymer A may include the monomeric structural unit (i) ethylenically unsaturated phosphorus-containing monomer in a concentration of 0.3 wt % to 2.4 wt %, based on the weight of Polymer A, and may be 0.3 wt % or more, 0.5 wt % or more, 0.6 wt % or more, 0.7 wt % or more, 0.8 wt % or more, 0.9 wt % or more, 1.0 wt % or more, 1.1 wt % or more, 1.2 wt % or more, 1.3 wt % or more, 1.4 wt % or more, 1.5 wt % or more, or even 1.6 wt % or more, while generally at a concentration of 2.4 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 1.7 wt % or less, desirably 0.9 wt % to 1.8 wt %. Polymer B may contain the monomeric structural unit (i) ethylenically unsaturated phosphorus-containing monomer in a concentration of zero to 2.5 wt %, or may be absent, and may be zero or more, 0.1 wt % or more, 0.2 wt % or more, 0.3 wt % or more, 0.4 wt % or more, or even 0.5 wt % or more, based on the weight of Polymer B, while generally at a concentration of 2.5 wt % or less, 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, desirably zero to 1.0 wt %.

[0031] One or both of polymer A and the polymers in the multi-stage polymer (desirably polymer A) may contain structural units of diacetone (meth)acrylamide. Polymer A may contain the monomeric structural unit (ii) diacetone (meth)acrylamide at a concentration of 0.1 wt % to 6.0 wt %, and may be 1.0 wt % or more, 1.2 wt % or more, 1.5 wt % or more, 1.8 wt % or more, 2.0 wt % or more, 2.2 wt % or more, 2.5 wt % or more, 2.8 wt % or more, or even 3 wt % or more, based on the weight of Polymer A, while generally at a concentration of 6.0 wt % or less, 5.5 wt % or less, 5.2 wt % or less, 5 wt % or less, 4.8 wt % or less, 4.5 wt % or less, 4.2 wt % or less, 4 wt % or less, 3.8 wt % or less, 3.6 wt % or less, 3.5 wt % or less, or even 3.2 wt % or less, desirably 1.5 wt % to 4 wt % or 2.0 wt % to 3.5 wt %. Polymer B may contain the monomeric structural unit (ii) diacetone (meth)acrylamide at a concentration of zero to 2.5 wt %, based on the weight of polymer B, and may be zero or more, 0.1 wt % or more, 0.2 wt % or more, 0.3 wt % or more, 0.4 wt % or more, or even 0.5 wt % or more, while generally at a concentration of 2.5 wt % or less, 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, desirably zero to 1.5 wt % or 0.5 wt % to 1.0 wt %.

[0032] One or both of polymer A and polymer B in the multi-stage polymer may comprise structural units of a vinyl aromatic monomer. Polymer A may comprise monomeric structural unit (iii) vinyl aromatic monomer structural units 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 by weight, while generally at a concentration of 75% or less, and may be 70% or less, 65% or less, 60% or less, or even 55% or less by weight, desirably 30% to 55% by weight. Polymer B may contain the monomeric structural unit (iii) vinyl aromatic monomer in a concentration of 10% to 100% by weight, based on the weight of polymer B, and may be 10% by weight or more, 25% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, or even 70% by weight or more, while generally at a concentration of 100% by weight or less, 95% by weight or less, 90% by weight or less, 85% by weight or less, or even 80% by weight or less, desirably 50% to 85% by weight.

[0033] Polymer A may be present in the multi-stage polymer at a concentration of 50% to 90% by weight, based on the weight of the multi-stage polymer, and may be 52% to 78%, 55% to 75%, 58% to 74%, 60% to 72%, 62% to 71%, or 65% to 70% by weight. Polymer B may be present in the multi-stage polymer at a concentration of 10% to 50% by weight, based on the weight of the multi-stage polymer, and may be 22% to 48%, 25% to 45%, 26% to 42%, 28% to 40%, 29% to 38%, or 30% to 35% by weight. Desirably, the multi-stage polymer comprises 55% to 85% by weight of Polymer A and 15% to 45% by weight of Polymer B, based on the weight of the multi-stage polymer.

[0034] Emulsion polymers useful in the present invention can have a number average molecular weight (Mn) of 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, while generally not exceeding 60,000 g / mol. The molecular weight of the emulsion polymer may be less than 55,000 g / mol, less than 50,000 g / mol, less than 45,000 g / mol, less than 40,000 g / mol, less than 38,000 g / mol, less than 35,000 g / mol, less than 32,000 g / mol, less than 30,000 g / mol, less than 29,000 g / mol, less than 28,000 g / mol, less than 27,000 g / mol, or even less than 26,000 g / mol, desirably between 10,000 g / mol and 30,000 g / mol. The molecular weight of the emulsion polymer may be measured by gel permeation chromatography (GPC) (further details are provided in the GPC analysis below).

[0035] The types and levels of the above monomers used to prepare the emulsion polymer can be selected to provide the emulsion polymer with a glass transition temperature (Tg) suitable for various applications. The Tg of the emulsion polymer can be -10 degrees Celsius (°C) or higher, -5°C or higher, 0°C or higher, 5°C or higher, 10°C or higher, or even 15°C or higher, while generally being 50°C or lower, 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.

[0036] The total concentration of the above-mentioned monomeric structural units (e.g., monomers (i)-(iv), and, if present, optionally monomers (v)-(viii)) in the emulsion polymer is equal to 100% by weight, based on the weight of the emulsion polymer. If the emulsion polymer is a multi-stage polymer, the total concentration of the above-mentioned monomeric structural units in both polymer A and polymer B can be equal to 100% by weight, based on the multi-stage polymer weight (i.e., emulsion polymer weight). The monomeric structural units in polymer A and polymer B, respectively, total 100% by weight, based on the weight of polymer A and polymer B, respectively.

[0037] Emulsion polymers useful in the present invention can be prepared by emulsion polymerization of a monomer mixture containing the above-mentioned monomers (e.g., monomers (i)-(iv) and, if present, optional monomers (v)-(viii)). The total concentration of monomers in the monomer mixture for preparing the emulsion polymer is equal to 100% by weight, 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 weight concentration of structural units of such monomer in the emulsion polymer relative to the weight of the emulsion polymer, as described above. The monomer mixture can be added neat, as an emulsion in water, or in one or more additions, or continuously, linearly or nonlinearly, over the reaction period to prepare the emulsion polymer. Suitable temperatures for the emulsion polymerization process can be below 100°C and can range from 10 to 99°C or from 50 to 90°C. One or more surfactants may be used in the preparation of the emulsion polymer. Emulsion polymers can be prepared by a single-stage emulsion polymerization or by a multi-stage emulsion polymerization process, thereby forming a multi-stage emulsion polymer. A multi-stage emulsion polymerization process includes at least two stages formed in succession, which typically results in the formation of a multi-stage polymer comprising at least polymer A and polymer B; optionally, the different stages can be formed in different reactors. Desirably, the multi-stage emulsion polymerization process includes a stage (desirably the first stage) in which polymer A is prepared in an aqueous medium, and a stage (desirably the second stage) in which polymer B is prepared, both by emulsion polymerization. This process can include a stage in which monomer mixture A is polymerized to form polymer A, and a stage in which monomer mixture B is polymerized to form polymer B. Desirably, the process for preparing a multi-stage polymer includes an initial polymerization stage to form polymer A, optionally a stage to neutralize polymer A, followed by a polymerization stage to form polymer B in the presence of polymer A. Monomer mixtures A and B may each independently comprise the monomers described above (eg, monomers (i)-(viii), if present) for forming the structural units of polymers A and B, respectively.The total concentration of the monomer mixture for preparing polymer A and polymer B relative to the total weight of monomers for preparing the multi-stage polymer can be equal to 100% by weight relative to the weight of the multi-stage polymer (e.g., the total weight of polymer A and polymer B). For each monomer, the concentration of the monomer relative to the total weight of monomers used in preparing a polymer (e.g., polymer A) is substantially the same as the concentration of structural units of such monomer relative to the total weight of such polymer (e.g., polymer A).

[0038] One or more free radical initiators may be used in the polymerization process. The polymerization process may be a thermally initiated or redox initiated emulsion polymerization. Examples of suitable free radical initiators include hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, ammonium and / or alkali metal persulfates, sodium perborate, superphosphate and their salts, potassium permanganate, and ammonium or alkali metal salts of peroxydisulfate. Free radical initiators may typically be used at levels of 0.01% to 3.0% by weight, based on the total weight of the monomers. Redox systems containing the above initiators combined with a suitable reducing agent may be used in the polymerization process. Examples of suitable reducing agents include sodium formaldehyde sulfoxylate, ascorbic acid, isoascorbic acid, alkali metal and ammonium salts of sulfur-containing acids, such as sodium sulfite, bisulfite, thiosulfate, hydrosulfite, sulfide, hydrogen sulfide, or dithionous acid, formamidine sulfinic acid, acetone bisulfite, glycolic acid, hydroxymethanesulfonic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid, and salts of the aforementioned acids. Metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium, or cobalt may be used to catalyze the redox reaction. Chelating agents for metals may optionally be used.

[0039] One or more surfactants may be used in the polymerization process to prepare emulsion polymers. The surfactant may be added before or during polymerization of the monomers or combinations thereof. A portion of the surfactant may also be added after polymerization. The surfactant may be used in at least one or all stages to prepare multistage polymers. 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 surfactants used is typically zero to 10% by weight, or 0.5% to 3% by weight, based on the weight of the total monomers (i.e., the monomer mixture) used to prepare the emulsion polymer.

[0040] One or more chain transfer agents may 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 may be used in the stage preparing polymer A, the stage preparing polymer B, or both stages. Examples of suitable chain transfer agents include hydroxyl-containing mercaptans such as 3-mercaptopropionic acid, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, n-dodecyl mercaptan, n-hexadecanethiol, tert-dodecyl mercaptan, n-octadecanethiol, benzenethiol, alkyl mercaptan azelates, hydroxyethyl mercaptan, mercaptopropionic acid, and mixtures thereof. Chain transfer agents may be used at concentrations of zero to 2% by weight, and may be greater than zero, greater than 0.05%, greater than 0.1%, or even greater than 0.15% by weight, while generally at concentrations of 2% by weight or less, and may be less than 1.5%, less than 1.0%, less than 0.5%, less than 0.3%, less than 0.25%, or even less than 0.20% by weight, based on the total weight of monomers used to prepare the emulsion polymer.

[0041] After polymerization is complete, the resulting aqueous dispersion (i.e., polymer emulsion) can be neutralized with one or more bases as neutralizing agents, for example, to a pH value of 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 may include ammonia; alkali metal or alkaline earth metal compounds such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, and the like; 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, neopentanediamine, dimethylaminopropylamine, hexamethylenediamine, 4,9-dioxadodecane-1,12-diamine, polyethyleneimine, or polyvinylamine; aluminum hydroxide; or mixtures thereof.

[0042] The emulsion polymer particles in the aqueous composition can have a particle size of 40 nanometers (nm) to 500 nm, and can be 60 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, more than 100 nm, 105 nm or more, or even 110 nm or more, while simultaneously being 500 nm or less, 300 nm or less, 200 nm or less, or even 150 nm or less. Particle size herein refers to Z-average size and can be measured by a Brookhaven BI-90 Plus Particle Size Analyzer.

[0043] The aqueous coating compositions of the present invention may contain emulsion polymers at a concentration of 1% to 30% by weight, and may be 1% or more, 2% or more, 3% or more, 4% or more, or even 5% or more by weight, based on the weight of the aqueous coating composition, while generally at a concentration of 30% or less, and may be 25% or less, 20% or less, 15% or less, or even 10% or less by weight.

[0044] The aqueous coating composition of the present invention may further comprise one or more polyfunctional carboxylic acid hydrazides containing at least two hydrazide groups per molecule. The polyfunctional carboxylic acid hydrazides may be selected from adipic acid dihydrazide, oxalic acid dihydrazide, isophthalic acid dihydrazide, polyacrylic acid polyhydrazide, or mixtures thereof. The polyfunctional carboxylic acid hydrazide may be present in a concentration of zero or greater, such as 0.05% by weight or greater, 0.1% by weight or greater, 0.2% by weight or greater, 0.4% by weight or greater, or even 0.6% by weight or greater, based on the weight of the emulsion polymer, while typically at a concentration of 3% by weight or less, 2% by weight or less, 1.5% by weight or less, or even 1% by weight or less.

[0045] The aqueous coating compositions of the present invention comprise one or more dicarboxylic acids, their salts, 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). Dicarboxylic acids useful in the present invention may have the structure of formula (I): HOOC-R-COOH(I) In the formula, R is an alkylene group, an alkenylene group, an alkynylene group, a cycloalkylene group, a cycloalkenylene group, a cycloalkynylene group, an arylene group, or a heterocyclic arylene group containing 6 to 18 carbon atoms (C6-C 18R may contain from 6 to 18 carbon atoms, and may have 7 or more carbon atoms, 8 or more carbon atoms, 9 or more carbon atoms, or even 10 or more carbon atoms, while generally having 18 or fewer carbon atoms, and may have 17 or fewer, 16 or fewer, 15 or fewer, or even 14 or fewer carbon atoms. Desirably, the dicarboxylic acid is a linear (i.e., unbranched) or branched chain aliphatic dicarboxylic acid. Desirably, R is a C6-C 18 It is an alkylene group (i.e., -(CH2) n -, where n is 6 to 18), more preferably C6 to C 14 The R group is an alkylene group. Desirably, the dicarboxylic acid is a saturated dicarboxylic acid. The aqueous coating composition can include a mixture of two or more dicarboxylic acids that differ in the R group, a mixture of salts of two or more different dicarboxylic acids, or a combination thereof.

[0046] Suitable dicarboxylic acids include, for example, sebacic acid (HOOC(CH 2 )8COOH), dodecanedioic acid (HOOC(CH2) 10 COOH), suberic acid (HOOC(CH2)6COOH), anchoic acid (HOOC(CH2)7COOH), undecanedioic acid (HOOC(CH2)9COOH), eicosanedioic acid (HOOC(CH2) 18 COOH), or mixtures thereof, but preferably sebacic acid.

[0047] Aqueous coating compositions typically contain a reaction mixture of at least one dicarboxylic acid (desirably sebacic acid) and at least one base. Bases useful for neutralizing (i.e., reacting with) the dicarboxylic acid may include those bases described above for neutralizing the aqueous dispersion of the emulsion polymer section, particularly ammonia, N,N-dimethylethanolamine, 2-amino-2-methyl-1-propanol, or mixtures thereof. The amount of base used to neutralize the dicarboxylic acid to form the salt of the dicarboxylic acid (also referred to as the "dicarboxylate salt") may be in an amount that provides a dry weight ratio of base to dicarboxylic acid ranging from 30:70 to 70:30, 35:65 to 65:35, 40:60 to 60:40, or 45:55 to 55:45. Aqueous coating compositions typically contain one or more salts of the dicarboxylic acid. Depending on the type of base used, the resulting salt of the dicarboxylic acid may be an ammonium salt, an alkali metal salt, an amine salt, or a mixture thereof. These salts may be mono-neutralized salts of dicarboxylic acids, bis-neutralized salts of dicarboxylic acids, or mixtures thereof.

[0048] Component (B) dicarboxylic acid and / or salt thereof may be present in an amount to provide -OOC-R-COO- segments in the aqueous coating composition at a concentration of 1.1 to 3.8 wt. % based on the weight of the emulsion polymer, and may be 1.1 wt. % or more, 1.2 wt. % or more, 1.5 wt. % or more, or even 1.8 wt. % or more, while generally being 3.8 wt. % or less, 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, desirably 1.1 to 2.0 wt. %. The -OOC-R-COO- segments may be derived from dicarboxylic acids and / or salts of dicarboxylic acids. The concentration of the -OOC-R-COO- segment can be determined by liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (NMR) analysis, and / or extraction analysis. Alternatively, the concentration of the -OOC-R-COO- segment can be calculated by the weight of the original, unneutralized dicarboxylic acid added relative to the weight of the aqueous coating composition. In the case of an aqueous coating composition containing a salt of a dicarboxylic acid, the weight of the dicarboxylic acid used to form such salt, instead of the weight of the salt, is used to calculate the concentration of the -OOC-R-COO- segment.

[0049] The aqueous coating composition of the present invention comprises one or more thio-, amido-, or imido-derivatives of triphosphonic acid, their salts, or mixtures thereof (component (C), also referred to as "triphosphonic acid derivatives"). The triphosphonic acid derivative may be selected from tri(thio)phosphonic acid, trihypophosphonic acid, (thio)imido-triphosphonic acid, or (thio)hydrazide-triphosphonic acid, their salts, or combinations thereof. Desirably, the triphosphonic acid derivative is selected from amino trimethylene phosphonic acid (ATMP) and aminotriethylene phosphonic acid, their salts, or combinations thereof. The aqueous coating composition may comprise a mixture of two or more thio-, amido-, or imido-derivatives of triphosphonic acid, their salts, or combinations thereof. The concentration of component (C), triphosphonic acid derivative, can range from 30% to 60% by weight, based on the weight of the emulsion polymer, and can be 30% by weight or more, 31% by weight or more, 32% by weight or more, 33% by weight or more, 34% by weight or more, or even 35% by weight or more, while generally being 60% by weight or less, 58% by weight or less, 56% by weight or less, 55% by weight or less, 52% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, or even 38% by weight or less, desirably 35% to 50% by weight.

[0050] 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·xSiO, where M represents an alkali metal, including lithium, sodium, potassium, and combinations thereof, and x represents the molar ratio of silica (SiO) to metal oxide (MO). Sodium silicate (NaO·xSiO) typically has a molar ratio of NaO to SiO ranging from 1:4 to 2:1. Potassium silicate (KO·xSiO) typically has a molar ratio of KO to SiO from 0.2 to 1. Lithium silicate (LiO·xSiO) typically has a molar ratio of LiO to SiO from 0.3 to 8. Mixed water-soluble alkali metal silicates may be used, such as potassium sodium silicate, lithium potassium silicate, or mixtures thereof. Potassium silicate, including all variable compositions between K2SiO5 and K2SiO7, may be used. Desirably, the water-soluble silicate is sodium silicate. Suitable sodium silicates may include, for example, sodium orthosilicate (Na4SiO4), sodium metasilicate (Na2SiO3), sodium disilicate (Na2SiO5), sodium tetrasilicate (Na2SiO9), sodium pyrosilicate (Na6SiO7), other sodium polysilicates, or mixtures thereof. The aqueous coating composition may include a mixture of two or more water-soluble alkali metal silicates. The water-soluble alkali metal silicate may typically be supplied as an aqueous solution containing 5% to 80%, 10% to 70%, or 15% to 60% by dry weight of the alkali metal silicate, based on the weight of such aqueous solution.

[0051] 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 1.2 to 3.7, and can be 1.2 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, or even 2.0 or more, while simultaneously being 3.7 or less, 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, desirably 1.5 to 3.0.

[0052] The aqueous coating composition of the present invention may comprise 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 their salts, or a combination thereof. Desirably, component (E) comprises or consists of tannic acid, a salt thereof, or a combination thereof. Component (E) may be present in the aqueous coating composition at a concentration of 40% to 52% by weight, based on the weight of the emulsion polymer, and may be 40% or more, 42% or more, 44% or more, 45% or more, 46% or more, or even 48% or more by weight, while at the same time being 52% or less, 51% or less, 50% or less, 49% or less, 48% or less, 47% or less, 46% or less, or even 45% or less by weight, desirably 45% to 49% by weight.

[0053] The aqueous coating composition of the present invention may or may not contain one or more pigments. As used herein, "pigment" refers to a material capable of materially contributing to the opacity or hiding power of the composition. Such materials typically have a refractive index greater than 1.8. Inorganic pigments typically include metal oxides. Examples of suitable inorganic pigments include titanium dioxide (TiO), zinc sulfide, lithopone, carbon black, iron oxide red, iron oxide black, lemon chrome yellow, or mixtures thereof. Organic pigments typically include Prussian blue, organic pigment yellow, organic pigment red, anticorrosion pigments, or mixtures thereof. Preferably, the pigment is selected from TiO, carbon black, or mixtures thereof. The pigment may be present in a total concentration of zero to 60 wt %, 10 to 50 wt %, 15 to 40 wt %, or 20 to 35 wt %, based on the weight of the aqueous coating composition. The pigment may or may not include an anticorrosion pigment. "Anti-corrosion pigment" refers to a pigment that can prevent or retard corrosion of steel through chemical reaction or chelation. Suitable anti-corrosion pigments include, for example, zinc phosphate, zinc molybdate, zinc oxide, aluminum tripolyphosphate, zinc molybdenum phosphate, calcium-modified zinc phosphate, organic molecule-modified zinc phosphate, or mixtures thereof. The anti-corrosion pigment can be present at a concentration of zero to 10 wt. % based on the weight of the aqueous coating composition, and can be zero or more, 0.5 wt. % or more, 1 wt. % or more, 2 wt. % or more, 3 wt. % or more, or even 4 wt. % or more, while generally at a concentration of 10 wt. % or less, 9 wt. % or less, 8 wt. % or less, 7 wt. % or less, or even 6 wt. % or less, 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.

[0054] The aqueous coating composition of the present invention may or may not contain one or more extenders. The term "extender" as used herein refers to a particulate inorganic material having a refractive index of 1.8 or less and greater than 1.3. Examples of suitable extenders include barium sulfate, talc, calcium carbonate, clay, calcium sulfate, aluminosilicates, other silicates (other than component (D)), zeolites, mica, diatomaceous earth, solid or hollow glass, ceramic beads, nepheline syenite, feldspar, diatomaceous earth, calcined diatomaceous earth, talc (hydrated magnesium silicate), silica, alumina, kaolin, pyrophyllite, perlite, barite, wollastonite, opaque polymers such as ROPAQUE™ Ultra E (ROPAQUE is a trademark of The Dow Chemical Company) available from The Dow Chemical Company, or mixtures thereof. The aqueous coating composition may include the extender at a concentration of zero to 60% by weight, which may be 10% to 50% by weight, 15% to 40% by weight, or 20% to 35% by weight, based on the weight of the aqueous coating composition.

[0055] The aqueous coating composition of the present invention may or may not contain one or more defoaming agents. The term "defoaming agent" as used herein refers to a chemical additive that reduces and prevents foam formation. The defoaming agent may be a silicone-based defoaming agent, a mineral oil-based defoaming agent, an ethylene oxide / propylene oxide-based defoaming agent, an alkyl polyacrylate, and mixtures thereof. Suitable commercially available defoaming agents include, for example, TEGO Airex 901W, TEGO Airex 902W, and TEGO Foamex 1488 polyether siloxane copolymer emulsions available from TEGO, BYK-022 and BYK-024 silicone defoaming agents available from BYK, and mixtures thereof. The defoaming agent may generally be present at a concentration of zero to 0.5 wt. %, based on the weight of the aqueous coating composition, and may be 0.02 wt. % to 0.4 wt. %, or 0.04 wt. % to 0.2 wt. %.

[0056] The aqueous coating compositions of the present invention may or may not contain one or more thickeners, also known as “rheology modifiers,” which may include polyvinyl alcohol (PVA), clay materials, acid derivatives, acid copolymers, urethane associate 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 acid polymers, hydrophobically modified alkali swellable emulsions (HASE) such as hydrophobically modified acrylic acid copolymers, associative thickeners such as hydrophobically modified ethoxylated urethane (HEUR), and cellulosic thickeners such as methylcellulose ether, hydroxymethylcellulose (HMC), hydroxyethylcellulose (HEC), hydrophobically modified hydroxyethylcellulose (HMHEC), sodium carboxymethylcellulose (SCMC), sodium carboxymethyl 2-hydroxyethylcellulose, 2-hydroxypropylmethylcellulose, 2-hydroxyethylmethylcellulose, 2-hydroxybutylmethylcellulose, 2-hydroxyethylethylcellulose, and 2-hydroxypropylcellulose. Preferably, the thickener is HEUR. The thickener may be present at a concentration of zero to 1.0 wt. %, or 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.

[0057] The aqueous coating composition of the present invention may or may not contain one or more wetting agents. The term "wetting agent" as used herein refers to a chemical additive that reduces the surface tension of the composition, allowing it to more easily spread or penetrate the surface of a substrate. Wetting agents may be polycarboxylate, anionic, zwitterionic, or nonionic. Suitable commercially available wetting agents include, for example, SURFYNOL 104 and SURFYNOL TG nonionic wetting agents based on acetylene diols, available from Evonik; BYK-190, TEGO-750W, and TEGO-755W solutions of high molecular weight block polymers with pigment-affinity groups, available from BYK and Evonik, respectively; BYK-346 and BYK-349 polyether-modified siloxanes, both available from BYK; or mixtures thereof. The wetting agent may be present at a concentration of from zero to 0.6 wt.%, or from 0.1 wt.% to 0.5 wt.%, or from 0.2 wt.% to 0.4 wt.%, based on the weight of the aqueous coating composition.

[0058] The aqueous coating composition of the present invention may or may not contain one or more coalescents. The term "coalescent" as used herein refers to a slow-evaporating solvent that coalesces polymer particles into a continuous film under ambient conditions. Examples of suitable coalescents include 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 mixtures thereof. Preferred coalescents include dipropylene glycol n-butyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, n-butyl ether, or mixtures thereof. The coalescent may be present at a concentration of from zero to 10% by weight, or may be from 0.2% to 8% by weight, or from 1% to 6% by weight, based on the weight of the aqueous coating composition.

[0059] The aqueous coating compositions of the present invention may or may not contain one or more dispersants. The dispersants may be polyacrylic or polymethacrylic acids with various monomers such as styrene, acrylate, or methacrylate esters, or maleic anhydride, diisobutylene, and other hydrophilic or hydrophobic comonomers, their salts, or mixtures thereof. The dispersants may be present at a concentration of zero to 2 wt. %, 0.1 wt. % to 1.5 wt. %, or 0.2 wt. % to 1 wt. %, based on the weight of the aqueous coating composition.

[0060] In addition to the above-mentioned components, the aqueous coating composition of the present invention may include any one or combination of the following additives: buffering agents, neutralizing agents, wetting agents, mildewcides, biocides, antiskinning agents, colorants, antioxidants, plasticizers, leveling agents, adhesion promoters, and grind vehicles. These additives may be present at a concentration of zero to 10% by weight, based on the weight of the aqueous coating composition, and may be 0.1% to 5% by weight, or 0.2% to 1% by weight. The aqueous coating composition may also include water at a concentration of 30% to 90% by weight, based on the weight of the aqueous coating composition, and may be 40% to 80% by weight, or 50% to 70% by weight.

[0061] The aqueous coating composition of the present invention can typically be prepared by mixing component (A) in an aqueous dispersion, component (B), component (D), and component (C), typically in aqueous solution, with component (E), and optionally the polyfunctional carboxylic acid hydrazide, pigment, and other optional components described above. All components in the aqueous coating composition, except for component (C), such as ATMP, may be mixed in any order, followed by final mixing with component (C). For example, the emulsion polymer and the dicarboxylic acid and / or salt thereof (preferably in aqueous solution) may be mixed first, followed by mixing with other components, if present. Alternatively, component (A) may be mixed first with components (D), (E), and other optional components, if present, followed by addition of component (B), followed by final addition of component (C) (desirably ATMP). Preferably, the pigment and / or extender are mixed with a dispersant to form a slurry of the pigment and / or extender.

[0062] The aqueous coating composition of the present invention is useful for rust conversion. The aqueous coating composition can be applied and adhered to substrates prone to corrosion, such as metal substrates. Metal substrates can include ferrous metals, such as cast iron, welded seams, and carbon steel. The aqueous coating composition can be applied directly to substrates, particularly to unpretreated substrates, such as rusted metal surfaces. The aqueous coating composition has the ability to convert rust (i.e., convert or react rust on metal surfaces). That is, after applying the aqueous coating composition of the present invention, the original porous rust on the surface of the substrate can be converted into a dark purple coordination compound, thereby forming a coating film (i.e., coating) on ​​the substrate, which is ready for application of a water-based acrylic coating composition. The coordination compound is insoluble in water and organic solvents.

[0063] The aqueous coating composition of the present invention is particularly suitable for forming a base coat of a multilayer coating that further includes one or more top coats made from an aqueous top coating composition other than the aqueous coating composition of the present invention described above. The present application also relates to a multilayer coating that includes a base coat made from the aqueous coating composition of the present invention and a top coat made from the aqueous top coating composition, where the base coat is present between the top coat and the substrate. The substrate is as described above. The multilayer coating can have a film thickness of 40 micrometers (μm) to 60 μm. The multilayer coating may have properties including, for example, (I) flash rust resistance having a flash rust rating of "0" according to ISO 8501-4:2006 after 24 hours of exposure at 23°C and 90% relative humidity (RH), (II) good initial water resistance as indicated by a blister rating of "8M" or better, preferably "8F" or "10," (III) good adhesion to the substrate as indicated by an adhesion classification of "4B" or better, preferably "5B" according to ASTM D3359, and (IV) good water resistance as indicated by a blister rating of "8M" or better, preferably "8F" or "10." These properties can be measured according to the test methods described in the Examples section below.

[0064] The aqueous top coating composition useful in the present invention may be an acrylic top coating composition containing an acrylic emulsion polymer useful as a binder. The acrylic emulsion polymer in the top coating composition may include the emulsion polymers described above as well as commercially available acrylic binders such as MAINCOTE™ HG-100, MAINCOTE™ HG-300, and PRIMAL™ AS-8508 emulsion polymers, all available from The Dow Chemical Company (MAINCOTE and PRIMAL are trademarks of The Dow Chemical Company). The top coating composition may also include one or more of the following components, which may be as described above: pigment, extender, defoamer, thickener, wetting agent, coalescent, dispersant, and polyfunctional carboxylic acid hydrazide containing at least two hydrazide groups per molecule. The top coating composition may include one or more optional additives described above.

[0065] The present invention relates to a method for preparing a coating (preferably a multi-layer coating). The method includes the steps of (i) providing an aqueous coating composition of the present invention, (ii) applying the aqueous coating composition directly to a substrate susceptible to corrosion, and (iii) drying or allowing the applied aqueous coating composition to dry, thereby forming a base coat on the substrate. When the coating is a multi-layer coating, the method may further include (iv) applying an aqueous acrylic top coating composition to the base coat obtained from step (iii), and (v) drying or allowing the applied aqueous top coating composition to dry so that the base coat is present between the substrate and the top coat, thereby forming a top coat. The coating is suitable for marine protective coatings, general industrial finishes, metal protective coatings, automotive coatings, traffic paints, exterior insulation and finish 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 the step of pre-treating the substrate surface (eg, by polishing), yet the resulting coating still has the properties described above.

[0066] Applying a coating composition (e.g., the aqueous coating composition of the present invention or the aqueous acrylic top coating composition) to a substrate can be done by conventional means, including brushing, dipping, rolling, and spraying. The aqueous coating composition is preferably applied by spraying. Standard spraying techniques and equipment for spraying, such as air-atomized spraying, air spraying, airless spraying, high-volume low-pressure spraying, and electrostatic spraying, such as electrostatic bell application, can be used, and either manual or automated methods can be used. After the coating composition is applied to a substrate, the composition can be dried or allowed to dry at a temperature ranging from 0 to 35°C, or at an elevated temperature, for example, from 35 to 60°C, to form a coating film (e.g., a base coat or top coat). [Example]

[0067] Some embodiments of the present invention will now be described in the following examples, in which all parts and percentages are by weight (wt %) based on emulsion polymer weight unless otherwise specified. Materials for use in the examples are described herein below.

[0068] [Table 1] OROTAN, RETAN, ACRYSOL, MAINCOTE, and PRIMAL are trademarks of The Dow Chemical Company.

[0069] Aqueous polymer dispersions containing emulsion polymers for use as binders in rust conversion coating composition samples were prepared according to the synthesis process described below.

[0070] Synthesis of aqueous polymer dispersion "PD40" Deionized (DI) water (409 grams (g)), FES32 surfactant (31%, 55 g), ST (892 g), BA (683 g), AA (33 g), PEM (6 g), MEUR (50%, 10 g), and n-DDM (4 g) were mixed together to produce a stable monomer emulsion. To DI water (728 g) under a nitrogen (N) atmosphere at 90°C, FES32 surfactant (31%, 6 g), monomer emulsion (54 g), and APS (6 g) in DI water (18 g) were added, followed by DI water (10 g) to form a reaction mixture. The remaining monomer emulsion, APS (2.5 g) in DI water (64 g), and ammonia (25%, 6 g) in DI water (62 g) were then added over 180 minutes (min) at 88° C. At the end of the polymerization, FeSO (0.01 g) in DI water (3 g) mixed with EDTA sodium salt (0.02 g) in DI water (3 g), a solution of t-BHP (4.9 g) dissolved in DI water (26 g), and a solution of IAA (2.3 g) in DI water (45 g) were added, all at 60° C., followed by the addition of ammonia (53 g) in DI water (25 g) at 50° C. to form an aqueous dispersion.

[0071] Synthesis of aqueous polymer dispersion "PD76" Stage 1 monomer emulsion (ME1) was prepared by mixing together 288 g of DI water, 29 g of AB / 20 surfactant (28.5%, 28.5%), 560 g of BA, 585 g of ST, 16 g of PEM, 30 g of MAA, 31 g of DAAM, 4.3 g of MEUR (50%, 50%), and 2.5 g of n-DDM to form a stable monomer emulsion. Stage 2 monomer emulsion (ME2) was prepared by mixing together 124 g of DI water, 13 g of AB / 20 surfactant (28.5%, 50%), 105 g of BA, 425 g of ST, 2 g of MEUR (50%, 50%), and 1.1 g of n-DDM to form a stable monomer emulsion.

[0072] DI water (879 g) was added to a 5-liter, four-neck round-bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and stirring was initiated. The contents of the flask were heated to 90°C under a N2 atmosphere. AB / 20 surfactant (28.5%, 10 g), MAA (5.3 g), ME1 (89 g), and APS (5.0 g) in DI water (46 g) were added to the flask, followed by a DI water (30 g) rinse. The remaining ME1, APS (1.6 g) in DI water (45 g), and ammonia (25%, 15 g) in DI water (43 g) were then added over 87 minutes. After the ME1 feed was completed, DI water (30 g) was added as a rinse. ME2 and APS (0.7 g) in DI water (20 g) were then added over 33 minutes. After the ME2 feed was completed, DI water (30 g) was added as a rinse. The temperature of the flask contents was maintained at 87–89 °C during the addition. At the end of the polymerization, a mixture of FeSO 7H O (0.014 g) in DI water (5 g) and EDTA sodium salt (0.028 g) in DI water (5 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. Then, ammonia (25%, 26 g) in DI water (26 g) and ADH (19 g) in DI water (67 g) were added to the flask at 50 °C to obtain an aqueous dispersion.

[0073] Synthesis of aqueous polymer dispersion "PD00" Stage 1 monomer emulsion (ME1) was prepared by mixing together 296 g of DI water, 32 g of AB / 20 surfactant (28.5%, BA (405 g), 685 g of ST), 16 g of PEM, 31 g of MAA, 128 g of AAEM, 4.5 g of MEUR (50%, AAEM), and 2.6 g of n-DDM to form a stable monomer emulsion. Stage 2 monomer emulsion (ME2) was prepared by mixing together 127 g of DI water, 14 g of AB / 20 surfactant (28.5%, BA (209 g), 340 g of ST), 1.9 g of MEUR (50%, AAEM), and 1.1 g of n-DDM to form a stable monomer emulsion.

[0074] DI water (899 g) was added to a 5-liter, four-neck round-bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and stirring was initiated. The contents of the flask were heated to 90°C under a N2 atmosphere. AB / 20 surfactant (28.5%, 7.5 g), MAA (5.5 g), ME1 (92 g), and APS (5.1 g) in DI water (46 g) were added to the flask, followed by a DI water (30 g) rinse. The remaining ME1, APS (1.6 g) in DI water (45 g), and ammonia (25%, 15 g) in DI water (43 g) were then added over 87 minutes. After the ME1 feed was completed, DI water (30 g) was added as a rinse. ME2 and APS (0.7 g) in DI water (20 g) were then added over 33 minutes. After the ME2 feed was completed, DI water (30 g) was added as a rinse. The contents of the flask were maintained at 87–89 °C during the addition. At the end of the polymerization, a mixture of FeSO 7H O (0.014 g) in DI water (5 g) and EDTA sodium salt (0.028 g) in DI water (5 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 added to the flask at 60 °C. Then, ammonia (25%, 39 g) in DI water (26 g) was added to the flask at 50 °C to obtain an aqueous dispersion.

[0075] Synthesis of aqueous polymer dispersion "PD29" 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 form a stable monomer emulsion. 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 form a stable monomer emulsion.

[0076] DI water (780 g) was added to a 5-liter, four-neck round-bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and stirring was initiated. The contents of the flask were heated to 90°C under a N2 atmosphere. B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and APS (5 g) in DI water (44 g) were added to the flask, followed by a DI water (45 g) rinse. The remaining ME1, APS (1.5 g) in DI water (71 g), and ammonia (25%, 15 g) in DI water (52 g) were then added over 87 minutes. After the ME1 feed was completed, DI water (30 g) was added as a rinse. ME2 and APS (0.7 g) in DI water (30 g) were then added over 33 minutes. After the ME2 feed was completed, DI water (30 g) was added as a rinse. The temperature of the flask contents was maintained at 87–89 °C during the addition. At the end of the polymerization, a mixture of FeSO 7H O (0.008 g) in DI water (5 g) and EDTA sodium salt (0.016 g) in DI water (5 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. Then, ammonia (25%, 26 g) in DI water (26 g) and ADH (26 g) in DI water (67 g) were added to the flask at 50 °C to obtain an aqueous dispersion.

[0077] Synthesis of aqueous polymer dispersion "PD31" 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 form a stable monomer emulsion. 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 form a stable monomer emulsion.

[0078] DI water (780 g) was added to a 5-liter, four-neck round-bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and stirring was initiated. The contents of the flask were heated to 90°C under a N2 atmosphere. B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and APS (5 g) in DI water (44 g) were added to the flask, followed by a DI water (45 g) rinse. The remaining ME1, APS (1.5 g) in DI water (71 g), and ammonia (25%, 15 g) in DI water (52 g) were then added over 87 minutes. After the ME1 feed was completed, DI water (30 g) was added as a rinse. ME2 and APS (0.7 g) in DI water (30 g) were then added over 33 minutes. After the ME2 feed was completed, DI water (30 g) was added as a rinse. The temperature of the flask contents was maintained at 87–89 °C during the addition. At the end of the polymerization, a mixture of FeSO 7H O (0.008 g) in DI water (5 g) and EDTA sodium salt (0.016 g) in DI water (5 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. Then, ammonia (25%, 26 g) in DI water (26 g) and ADH (5.3 g) in DI water (14 g) were added to the flask at 50 °C to obtain an aqueous dispersion.

[0079] Synthesis of aqueous polymer dispersion "PD41" 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 form a stable monomer emulsion. 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 form a stable monomer emulsion.

[0080] DI water (780 g) was added to a 5-liter, four-neck round-bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and stirring was initiated. The contents of the flask were heated to 90°C under a N2 atmosphere. B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and APS (5 g) in DI water (44 g) were added to the flask, followed by a DI water (45 g) rinse. The remaining ME1, APS (1.5 g) in DI water (71 g), and ammonia (25%, 15 g) in DI water (52 g) were then added over 87 minutes. After the ME1 feed was completed, DI water (30 g) was added as a rinse. ME2 and APS (0.7 g) in DI water (30 g) were then added over 33 minutes. After the ME2 feed was completed, DI water (30 g) was added as a rinse. The temperature of the flask contents was maintained at 87–89 °C during the addition. At the end of the polymerization, a mixture of FeSO 7H O (0.008 g) in DI water (5 g) and EDTA sodium salt (0.016 g) in DI water (5 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. Then, ammonia (25%, 26 g) in DI water (26 g) and ADH (18.5 g) in DI water (48 g) were added to the flask at 50 °C to obtain an aqueous dispersion.

[0081] Synthesis of aqueous polymer dispersion "PD42" 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 form a stable monomer emulsion. 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 form a stable monomer emulsion.

[0082] DI water (780 g) was added to a 5-liter, four-neck round-bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and stirring was initiated. The contents of the flask were heated to 90°C under a N2 atmosphere. B-11 surfactant (54%, 4.7 g), MAA (5.3 g), ME1 (89 g), and APS (5 g) in DI water (44 g) were added to the flask, followed by a DI water (45 g) rinse. The remaining ME1, APS (1.5 g) in DI water (71 g), and ammonia (25%, 15 g) in DI water (52 g) were then added over 87 minutes. After the ME1 feed was completed, DI water (30 g) was added as a rinse. ME2 and APS (0.7 g) in DI water (30 g) were then added over 33 minutes. After the ME2 feed was completed, DI water (30 g) was added as a rinse. The temperature of the flask contents was maintained at 87–89 °C during the addition. At the end of the polymerization, a mixture of FeSO 7H O (0.008 g) in DI water (5 g) and EDTA sodium salt (0.016 g) in DI water (5 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. Then, ammonia (25%, 26 g) in DI water (26 g) and ADH (18.5 g) in DI water (48 g) were added to the flask at 50 °C to obtain an aqueous dispersion.

[0083] The as-prepared polymer dispersions were characterized according to the following test methods and the properties are shown in Table 1.

[0084] Solid content The solids content of the aqueous polymer dispersion was determined by weighing a 0.7±0.1 g sample (the wet weight of the sample is designated "W1"), placing the sample in an aluminum pan (the weight of the aluminum pan is designated "W2") in a 150°C oven for 25 minutes, then allowing it to cool to room temperature and weighing the aluminum pan containing the dried sample (the total weight is designated "W3"). "W3-W2" refers to the dry weight or solids weight of the sample. The solids content was calculated by (W3-W2) / W1 x 100%.

[0085] GPC analysis The number average molecular weight (M n ) was measured by GPC analysis, typically performed on an Agilent 1200. Samples were dissolved in tetrahydrofuran (THF) / formic acid (FA) (5%) at a concentration of 2 milligrams per milliliter (mg / mL), stirred for 1 hour, stored at room temperature overnight, and then filtered through a 0.45 μm polytetrafluoroethylene (PTFE) filter before GPC analysis. GPC analysis was performed under the following conditions: Columns: one PL Gel GUARD column (10 μm, 50 millimeters (mm) × 7.5 mm) in tandem, two Mixed B columns (7.8 mm × 300 mm); column temperature: 40 °C; mobile phase: THF / FA (5%); flow rate: 1.0 mL / min; injection volume: 100 μL; detector: Agilent refractive index detector, 40 °C; and calibration curve: PL Polystyrene I Narrow standards with molecular weights ranging from 2,329,000 to 580 g / mol, polynom 3 fitness.

[0086] [Table 2] * The Fox Tg of the emulsion polymer in the polymer dispersion was calculated by the Fox equation. Particle size was measured by a Brookhaven BI-90 Plus Particle Size Analyzer. NA = Not Applicable.

[0087] Preparation of dicarboxylic acid solutions (1) Preparation of an aqueous solution of neutralized sebacic acid (“sebacic acid solution”): Sebacic acid (6.00 g), aqueous ammonia (25%, 19.53 g), and water (1.74 g) were mixed and stirred to obtain a clear solution containing sebacic acid, mono-ammonium sebacate, bis-ammonium sebacate, or a mixture thereof. (2) Preparation of an aqueous solution of neutralized succinic acid (“succinic acid solution”): Succinic acid (6.00 g), aqueous ammonia (25%, 19.53 g), and water (1.74 g) were mixed and stirred to obtain a clear solution containing succinic acid, mono-ammonium succinate, bis-ammonium succinate, or a mixture thereof. (3) Preparation of an aqueous solution of neutralized adipic acid (“adipic acid solution”): Adipic acid (6.00 g), aqueous ammonia (25%, 19.53 g), and water (1.74 g) were mixed and stirred to obtain a clear solution containing adipic acid, mono-ammonium adipate, bis-ammonium adipate, or a mixture thereof.

[0088] Waterborne acrylic top coating composition The formulation of the waterborne acrylic top coating composition is shown in Table 2, with the amount of each component reported in grams (g). A pigment grind was prepared by mixing the components in a grind using a high-speed grinder at 1500 revolutions per minute (RPM) for 20 minutes. The binder was premixed with water and aqueous ammonia to adjust the pH to greater than 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 kreb units (KU), measured at room temperature using a BROOKFIELD™ KU-3 viscometer, thereby forming the waterborne acrylic top coating composition.

[0089] [Table 3]

[0090] Rust conversion coating composition samples The formulations of direct-to-metal (DTM) rust conversion coating compositions are shown in Tables 3 and 4, with the amount of each component reported in grams (g). To prepare compositions IE1-11 shown in Table 3, tannic acid was dissolved in a mixture of ethanol and water, followed by the addition of isopropanol. To the resulting solution, the aqueous polymer dispersion (as a binder) prepared above was added, followed by the addition of TEXANOL ester alcohol. The sodium silicate solution and dicarboxylic acid solution prepared above were then added, in order. The ATMP solution was then added to the resulting mixture, followed by the addition of aqueous ammonia to adjust the pH to above 7.0. Finally, the resulting composition was filtered through a 325 mesh (45 μm) screen to separate any gels present. The compositions used in CE1-18 were prepared substantially the same as above, except that some components were omitted or different, as shown in Table 4. All resulting rust conversion coating composition samples were evaluated according to the following test methods, and the property and characterization results are shown in Tables 3 and 4.

[0091] Preparation of coated panels First, a sandblasted steel panel (Model H·HONG™ standard test panel from Guangdong Honghong Industrial Co., Ltd.) was exposed to a salt spray environment (5% sodium chloride fog in a Q-Fog cyclic corrosion tester, Model No. Q-FOG / CCT1100) for 24 hours to generate rust on the panel surface. The rusted panel was then rinsed with DI water to remove the salt on the surface. After drying, the panel was polished with 240-grit abrasive paper to remove loose rust from the panel surface, but the rust firmly attached to the panel remained on the panel surface. The panel surface was further treated with alcohol to remove the rust-preventing oil.

[0092] The rust conversion coating composition samples (1.5 g) listed in Tables 3 and 4 were brushed onto the resulting panels using an art 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. The surface of the coated panel gradually turned a deep black-purple color while the panel was left under ambient conditions (23°C and 50% RH) for 48 hours. The aqueous acrylic top coating composition samples (1.5 g) prepared above as listed in Table 2 were then further brushed onto the panel using an art brush (same source as above), thereby obtaining coated panels with a final dry film thickness of 18 μm to 20 μm. The as-prepared coated panels (hereinafter "coated panels") were then characterized according to the following test methods: Flash rust resistance test The coated panels prepared above were immediately placed in an environmental chamber (23°C and 90% RH) for 24 hours. After that, the coated panels were removed and evaluated for flash rust rating according to ISO 8501-4:2006 and the rust ranking shown in Table A below. An acceptable flash rust rating is "0".

[0093] [Table 4]

[0094] The rust rating may include the degree of rust, with "S" representing spot, "G" representing general, and "P" representing pinpoint, and the grading by percentage of surface rust is as follows: "10" means 0.01% by weight or less, "9" means greater than 0.01% and a maximum of 0.03%, "8" means greater than 0.03% and a maximum of 0.1%, "7" means greater than 0.1% and a maximum of 0.3%, "6" means greater than 0.3% and a maximum of 1.0%, "5" means greater than 1.0% and a maximum of 3.0%, "4" means greater than 3.0% and a maximum of 10.0%, "3" means greater than 10.0% and a maximum of 16.0%, "2" means greater than 16.0% and a maximum of 33.0%, "1" means greater than 33.0% and a maximum of 50.0%, and "0" means greater than 50.0%. The acceptable rust rating is "10."

[0095] Initial water resistance test 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 a blister rating was then performed according to ASTM D714-02(2009) consisting of a number and / or one or more letters, as shown in Table B. The letters F, M, MD, or D qualitatively represent the density of blisters. The number refers to the size of the blisters, with 2 being the largest size, 8 being the smallest size, and 10 being no blisters. The higher the number, the smaller the blister size. Panels with a blister rating of "8M" or higher (preferably "8F" or "10") are acceptable and indicate good initial water resistance.

[0096] [Table 5]

[0097] Water resistance test 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 surfaces of the panels after immersion were then visually observed and blister rated according to the same procedures and criteria as described above in the initial water resistance test. Panels with a blister rating of "8M" or higher (preferably "8F" or "10") are acceptable and indicate good water resistance.

[0098] Adhesion Test The coated panels prepared above were allowed to dry for 7 days at 23°C and 50% RH and then evaluated for adhesion properties according to ASTM D3359. Panels with a classification of "4B" or higher (preferably "5B") are acceptable and indicate good adhesion to the steel panel surface.

[0099] The properties and characterization of the coated panels are shown in Tables 3 and 4. As shown in Table 3, the rust conversion coating samples IE1-11, each containing a multistage emulsion polymer binder containing a specific content of PEM and DAAM structural units combined with sebacic acid, tannic acid, sodium silicate, and ATMP at a specific concentration (after rust conversion), provided a synergistic effect in significantly improving the properties of the coatings containing different waterborne acrylic topcoats, including initial water resistance, water resistance, and adhesion properties, as well as flash rust resistance.

[0100] In contrast, rust conversion coating composition samples that did not contain any one or more of the claimed ingredients and / or were outside the claimed range failed the requirements for one or more of the above properties after rust conversion. Replacing sebacic acid with an equal amount of succinic acid or adipic acid (CE2 and 3) resulted in a significant decrease in flash rust resistance and adhesion properties compared to IE1. The flash rust resistance properties of CE2 and 3 were even worse than the sample without the dicarboxylic acid (CE1). In the absence of ATMP, sample CE5 exhibited impaired flash rust resistance and significantly reduced adhesion properties. In the absence of silicate (CE6), tannic acid (CE7), or both ATMP and silicate (CE9), all properties of these samples were dramatically impaired. Replacing ATMP with phosphorous acid resulted in slightly poorer flash rust resistance and early water resistance (CE12). The use of binder PD76 alone, without the combination of tannic acid, sodium silicate, and ATMP, resulted in poor flash rust resistance and adhesion properties, even in the presence of sebacic acid (CE8). Sample CE10, with a silicate / ATMP ratio of 1.0, showed reduced flash rust resistance and poor adhesion, while sample CE18, with a silicate / ATMP ratio of 4, exhibited impaired initial water resistance. When AAEM was used instead of DAAM to prepare the binder in the rust conversion coating (CE11), initial water resistance and adhesion properties were impaired, but flash rust resistance was maintained, demonstrating that initial water resistance and adhesion properties are not necessarily related to flash rust resistance. Sample CE4, containing acrylic binder PD40 and subsequently added ADH in the basecoat, did not show significant improvement in flash rust resistance, although adhesion was slightly improved. Sample CE13, using an emulsion polymer containing 0.5 wt% DAAM structural units in the rust conversion coating, exhibited poor flash rust resistance and adhesion properties. The CE14 sample, which contained 4.0 wt. % sebacic acid in the rust conversion coating, exhibited poor adhesion and initial water resistance.Samples CE15 and 16, which used too low or too high loadings of tannic acid in the rust conversion coating (30 wt. % and 70 wt. %, respectively, based on dry polymer), failed all requirements for flash rust resistance, adhesion, and early water resistance properties. CE17 showed that too low a loading of ATMP (20 wt. %) in the rust conversion coating resulted in poor flash rust resistance and adhesion properties. Furthermore, both samples CE16 and 17 had tannic acid to ATMP ratios higher than 1.75 (1.97 and 2.42, respectively).

[0101] [Table 6] * In Tables 3 and 4, "Sodium silicate solutions" were prepared by dissolving sodium metasilicate solid in water to obtain solutions of different concentrations: 5 wt%, 10 wt%, and 15 wt%. Unless otherwise stated, sodium silicate solution (5% solution) was used. The IE9 sample used a 10% solution, and the CE18 sample used a 15% solution. "Sebacic acid content" refers to the content of -OOC-R-COO- segments calculated by the weight of sebacic acid (raw material) originally added in forming the sebacic acid solution used to prepare the sample relative to the dry weight of emulsion polymer in the rust conversion coating composition. All contents in Tables 3 and 4 refer to weight percentages based on the dry weight of the emulsion polymer in the rust conversion coating composition unless otherwise stated. "Silicate / phosphonic acid ratio" refers to the dry weight ratio of sodium silicate / ATMP, whereas in CE12 it refers to the dry weight ratio of sodium silicate / phosphorous acid.

[0102] [Table 7]

Claims

1. A water-based coating composition, (A) Emulsion polymer, (i) Structural units of ethylenically unsaturated phosphorus-containing monomers in an amount of 0.48% to 1.5% by weight, (ii) 0.7% to 3% by weight of diacetone(meth)acrylamide structural units, (iii) Structural units of vinyl aromatic monomers in an amount of 10% to 80% by weight, (iv) Structural units of alkyl (meth)acrylate, (v) Structural units of 0 to 5% by weight of α,β-ethylenically unsaturated carboxylic acids, salts thereof, or mixtures thereof, Emulsion polymer containing, (B) A dicarboxylic acid, a salt thereof, or a mixture thereof, wherein the dicarboxylic acid has the structure of formula (I): HOOC-R-COOH In the formula, R is alkylene, alkenylene, alkylylene, cycloalkylene, cycloalkenylene, cycloalkylylene, arylene, or heterocyclic arylene, and contains 6 to 18 carbon atoms. (B) The dicarboxylic acid, the salt thereof, or mixture thereof is present in an amount that provides the -OOC-R-COO- segment at a concentration of 1.1% to 3.8% by weight, (C) 30% to 60% by weight of a thio-, amido-, or imide- derivative of triphosphonic acid, a salt thereof, or a mixture thereof, (D) a water-soluble alkali metal silicate, which is present in an amount that provides a dry weight ratio of (D) the water-soluble alkali metal silicate to (C) a thio-, amido-, or imide- derivative of the triphosphonic acid, the salt thereof, or a mixture thereof in the range of 1.2 to 3.7, (E) comprising 40% to 52% by weight of tannic acid, gallic acid, pyrogallol, or citric acid, their salts, or combinations thereof, An aqueous coating composition in which the weight percentage is relative to the weight of the emulsion polymer.

2. The aqueous coating composition according to claim 1, wherein the dicarboxylic acid is selected from sebacic acid, dodecanediic acid, suberic acid, aconic acid, undecanediic acid, eicosanedioic acid, and mixtures thereof.

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

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

5. The aqueous coating composition according to claim 1, 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, wherein the emulsion polymer has a glass transition temperature of -10°C to 50°C, calculated by the Fox formula.

7. The aqueous coating composition according to claim 1, 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 emulsion polymer is a multi-stage polymer comprising 50% to 90% by weight of polymer A and 10% to 50% by weight of polymer B, based on the weight of the multi-stage polymer. The polymer A comprises, based on the weight of polymer A, 0.3% to 2.4% by weight of structural units of the ethylenically unsaturated phosphorus-containing monomer, 1% to 6% by weight of structural units of the diacetone (meth)acrylamide, and 10% to 75% by weight of structural units of the vinyl aromatic monomer. The polymer B comprises, based on the weight of polymer B, 0 to 2.5% by weight of structural units of the ethylenically unsaturated phosphorus-containing monomer, 0 to 2.5% by weight of structural units of the diacetone (meth)acrylamide, and 10% to 100% by weight of structural units of the vinyl aromatic monomer. The aqueous coating composition according to claim 1, wherein at least one of polymers A and B also includes the structural unit of alkyl (meth)acrylate.

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

10. A method for preparing a coating, (i) To provide an aqueous coating composition according to any one of claims 1 to 9, (ii) Direct application of the aqueous coating composition onto a corrosive substrate, (iii) Drying or enabling the drying of the applied aqueous coating composition, thereby forming a base coat on the substrate, and optionally, A method comprising: (iv) applying an aqueous top coating composition containing an acrylic emulsion polymer to the base coat obtained from step (iii); and (v) drying the applied aqueous top coating composition or allowing it to dry so that the base coat is located between the substrate and the top coat, thereby forming a top coat.