Aqueous polymer composition and process for its preparation

Abstract

An aqueous polymer composition comprising: (A) a specific emulsion polymer comprising structural units of a (meth)acrylic cycloalkyl ester, structural units of an acetoacetoxy or acetoacetamide functional monomer, and structural units of a phosphorous acid monomer, a salt thereof, or a mixture thereof; and (B) a specific amount of an aqueous resin comprising at least one fatty acid ester segment and having a number average molecular weight of 20,000 g / mol or less, based on the total dry weight of the emulsion polymer and the aqueous resin. Coating compositions comprising such aqueous polymer compositions provide coatings prepared therefrom having improved corrosion resistance properties.

Description

TECHNICAL FIELD

[0001] The present invention relates to an aqueous polymer composition and a method of making the same. BACKGROUND

[0002] Solvent-borne coating compositions containing epoxy, polyurethane or alkyd resins are widely used in metal protective coatings due to their corrosion resistance, mechanical properties and appearance. Aqueous acrylic polymer dispersions have much less environmental issues than solvent-borne dispersions and are commonly used for light to medium metal protection. Black coatings, which typically include carbon black as the main pigment, are widely used for machine and equipment accessory coatings. In the manufacture of black coatings by dispersing carbon black, a ball mill or a sand mill has traditionally been used. Due to its hydrophobic and low density properties, carbon black is more difficult to wet and well dispersed in water by conventional dispersion processes alone than inorganic pigments such as titanium dioxide. In order to facilitate the wetting and dispersion of carbon black, a large amount of hydrophilic additives is typically added to black coatings, however, this can compromise the corrosion resistance of the resulting coatings. Therefore, it is more challenging to improve the corrosion resistance of black coatings compared to coatings with other colors. In addition, direct-to-metal (DTM) coatings, especially in rainy areas, also require sufficient water resistance to avoid blistering caused by rainwater, as blistering can also have a negative impact on appearance and corrosion resistance.

[0003] Therefore, there is still a need to provide an aqueous polymer composition that is particularly suitable for use in coatings with the above-mentioned corrosion resistance properties. SUMMARY

[0004] The present invention provides a novel aqueous polymer composition that is particularly suitable for use in coating applications without the above-mentioned problems. The aqueous polymer composition of the present invention comprises a novel combination of a specific emulsion polymer and a specific aqueous resin. The aqueous polymer composition can provide coatings including black coatings with excellent corrosion resistance, which is characterized by a maximum creep at a 2 millimeter (mm) scribe line after exposure to salt spray for at least 130 hours. The aqueous polymer composition can also provide coatings with good early water resistance, as measured according to the test methods described in the Examples section below.

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

[0006] (A) an emulsion polymer, which emulsion polymer comprises, based on the weight of the emulsion polymer, 5 to 28 weight percent of structural units of a (meth)acrylic cycloalkyl ester,

[0007] 0.1 to 10 weight percent of structural units of an acetoacetoxy or acetoacetamide functional monomer,

[0008] 0.05 to 10 weight percent of structural units of a phosphorous acid monomer, a salt thereof, or a mixture thereof,

[0009] zero to 10 weight percent of an additional ethylenically unsaturated acid monomer, and

[0010] structural units of an additional ethylenically unsaturated nonionic monomer; and

[0011] (B) 0.7 to 7.8 dry weight percent of an aqueous resin, based on the total dry weight of the emulsion polymer and the aqueous resin, the aqueous resin comprising at least one fatty acid ester segment and having a number average molecular weight of 20,000 grams per mole (g / mol) or less.

[0012] In a second aspect, the present invention is a method of making the aqueous polymer composition of the first aspect by mixing the emulsion polymer with the aqueous resin.

[0013] In a third aspect, the present invention is a coating composition comprising the aqueous polymer composition of the first aspect and optionally a pigment. DETAILED DESCRIPTION

[0014] An “aqueous” composition or dispersion herein means particles dispersed in an aqueous medium. An “aqueous medium” herein refers to water and 0% to 30% by weight, based on the weight of the medium, of water-miscible compound(s) such as, for example, an alcohol, a glycol, a glycol ether, a glycol ester, or a mixture thereof.

[0015] “Structural unit” (also referred to as “polymerization unit”) of a named monomer refers to the residue of the monomer after polymerization, i.e., the polymerized monomer or monomer in polymerized form. For example, the structural unit of methyl methacrylate is shown below:

[0016] where the dashed line represents the point of attachment of the structural unit to the polymer backbone.

[0017] “Fatty acid ester segment” herein refers to (i) the residue of a fatty acid after esterification, or (ii) the residue of an unsaturated fatty acid ester after polymerization, i.e., the structural unit of the unsaturated fatty acid ester. For example, the fatty acid ester segment derived from esterified tung oil acid dimer and the fatty acid ester segment derived from polymerized sulfated castor oil (i.e., the structural unit of sulfated castor oil) are shown as (i-1) and (ii-1), respectively:

[0018]

[0019] where the dashed line represents the point of attachment of the segment to the resin backbone.

[0020] As used herein, “acrylic” monomers include (meth)acrylic acid, alkyl (meth)acrylates, (meth)acrylamides, (meth)acrylonitrile, and modified versions thereof, such as hydroxy alkyl (meth)acrylates. Throughout the document, the word fragment “(meth)acryl” refers to both “methacryl” and “acryl.” For example, (meth)acrylic acid refers to both methacrylic acid and acrylic acid, and (meth)acrylic acid methyl ester refers to both methacrylic acid methyl ester and acrylic acid methyl ester.

[0021] As used herein, “glass transition temperature” or “T g ” can be measured by various techniques, including, for example, differential scanning calorimetry (“DSC”) or by calculation using the Fox equation. The particular values of Tg reported herein are values calculated using the Fox equation (T.G. Fox, Bull. Am. Physics Soc., Vol. 1, No. 3, p. 123 (1956)). For example, the T g ,

[0022] where T g (calculated) is the glass transition temperature calculated for the copolymer, w(M1) is the weight fraction of monomer M1 in the copolymer, w(M2) is the weight fraction of monomer M2 in the copolymer, T g (M1) is the glass transition temperature of the homopolymer of monomer M1, and T g (M2) is the glass transition temperature of the homopolymer of monomer M2, all temperatures in K. The glass transition temperatures of homopolymers can be found, for example, in “Polymer Handbook,” edited by J. Brandrup and E.H. Immergut, Interscience Publishers.

[0023] The aqueous polymer composition of the present invention comprises one or more emulsion polymers. The emulsion polymer useful in the present invention includes one or more structural units of a cycloalkyl (meth)acrylate. Examples of suitable cycloalkyl (meth)acrylates include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dihydridodicyclopentadienyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, or mixtures thereof. Preferred cycloalkyl (meth)acrylates include cyclohexyl methacrylate, cyclohexyl acrylate, methylcyclohexyl acrylate, or mixtures thereof. The emulsion polymer can include the structural units of cycloalkyl (meth)acrylate in an amount of 5 wt.% or more, 6 wt.% or more, 7 wt.% or more, 8 wt.% or more, 9 wt.% or more, 10 wt.% or more, 11 wt.% or more, 12 wt.% or more, 13 wt.% or more, 14 wt.% or more, or even 15 wt.% or more, and at the same time 28 wt.% or less, 27 wt.% or less, 26 wt.% or less, 25 wt.% or less, 24 wt.% or less, 23 wt.% or less, 22 wt.% or less, 21 wt.% or less, or even 20 wt.% or less, based on the weight of the emulsion polymer. The "weight of the emulsion polymer" herein refers to the dry weight of the emulsion polymer.

[0024] The emulsion polymer useful in the present invention can include one or more structural units of an acetoacetoxy or acetoacetamide functional monomer. The acetoacetoxy or acetoacetamide functional monomer is a monomer having ethylenic unsaturation and one or more acetoacetyl moieties represented by the formula:

[0025] wherein R 1 is hydrogen, an alkyl group having 1 to 10 carbon atoms, or a phenyl group.

[0026] Examples of suitable acetoacetoxy or acetoacetamide functional groups include wherein X is O or N, R1is a divalent radical and R2is a trivalent radical that links the acetoacetoxy or acetoacetamide functional group to the backbone of the emulsion polymer.

[0027] Suitable acetoacetoxy or acetoacetamide functional monomers can include, for example, acetoacetoxyalkyl (meth)acrylates such as acetoacetoxyethyl methacrylate (AAEM), acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, acetoacetoxybutyl methacrylate, and 2,3-di(acetoacetoxy)propyl methacrylate; acetoacrylic acid allyl ester; acetoacrylic acid vinyl ester; acetoacetamidoalkyl (meth)acrylates such as acetoacetamidoethyl methacrylate and acetoacetamidoethyl acrylate; or combinations thereof. The emulsion polymer can include structural units of acetoacetoxy or acetoacetamide functional monomers in an amount of 0.1 wt% or more, 0.3 wt% or more, 0.5 wt% or more, 0.8 wt% or more, 1 wt% or more, 1.2 wt% or more, 1.5 wt% or more, 1.8 wt% or more, 2 wt% or more, 2.2 wt% or more, 2.5 wt% or more, 2.8 wt% or more, 3 wt% or more, or even 3.2 wt% or more, and at the same time 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4.5 wt% or less, 4 wt% or less, 3.8 wt% or less, 3.6 wt% or less, or even 3.4% or less, based on the weight of the emulsion polymer.

[0028] The emulsion polymer useful in the present application can include structural units of one or more phosphorous acid monomers, salts thereof, or mixtures thereof. The phosphorous acid monomer can have ethylenic unsaturation. The phosphorous acid monomer can be a dihydrogen phosphate ester of an alcohol, where the alcohol contains a polymerizable vinyl or olefin group or is substituted therewith. The phosphorous acid monomers and salts thereof can include phosphoalkyl (meth)acrylates such as phosphoethyl (meth)acrylate, phosphopropyl (meth)acrylate, phosphobutyl (meth)acrylate, salts thereof, and mixtures thereof; CH2=C(R p1 )-C(O)-O-(R p2 O) q -P(O)(OH)2, where R p1 = H or CH3, R p2= alkylene, such as an ethylene group, a propylene group, or a combination thereof; and q = 1-20, such as SIPOMER PAM-100, SIPOMER PAM-200, SIPOMER PAM-300, and SIPOMER PAM-600, all commercially available from Solvay; a phosphorus alkoxyl (meth)acrylate, such as phosphoethylene glycol (meth)acrylate, phosphodiethylene glycol (meth)acrylate, phosphotriethylene glycol (meth)acrylate, phosphopropylene glycol (meth)acrylate, phosphodipropylene glycol (meth)acrylate, phosphotripropylene glycol (meth)acrylate, a salt thereof, or a mixture thereof. A preferred phosphorous acid monomer is selected from the group consisting of phosphoethyl methacrylate (PEM), phosphoethyl acrylate, an allyl ether phosphoester, or a mixture thereof; more preferably, phosphoethyl methacrylate. The emulsion polymer can include structural units of the phosphorous acid monomer, a salt thereof, or a mixture thereof in an amount of 0.05 wt% or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.8 wt% or more, 1.0 wt% or more, 1.2 wt% or more, 1.3 wt% or more, 1.4 wt% or more, or even 1.5 wt% or more, and at the same time 10 wt% or less, 7 wt% or less, 5 wt% or less, 4.5 wt% or less, 4 wt% or less, 3.5 wt% or less, 3.2 wt% or less, 3 wt% or less, 2.8 wt% or less, 2.5 wt% or less, 2 wt% or less, or even 1.8 wt% or less, based on the weight of the emulsion polymer.

[0029] The emulsion polymer useful in the present application can include one or more additional ethylenically unsaturated acid monomers, salts thereof, or mixtures thereof, different from the phosphorous acid monomer or salt thereof. The additional ethylenically unsaturated acid monomer can be a carboxylic acid monomer, a sulfonic acid monomer, or mixtures thereof. The carboxylic acid monomer can be an α,β-ethylenically unsaturated carboxylic acid, a monomer bearing an acid-forming group that generates or subsequently converts into such an acid group (such as an acid anhydride, a (meth)acrylic anhydride, or a maleic anhydride); and mixtures thereof. Specific examples of α,β-ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, fumaric acid, 2-carboxyethyl acrylate, or mixtures thereof. The sulfonic acid monomer can include sodium vinyl sulfonate (SVS), sodium styrene sulfonate (SSS), and acrylamido-methyl-propane sulfonate (AMPS); salts thereof; or mixtures thereof. Preferably, the additional ethylenically unsaturated acid monomer is an α,β-ethylenically unsaturated carboxylic acid, for example, acrylic acid, methacrylic acid, itaconic acid, or mixtures thereof. The emulsion polymer can include structural units of the additional acid monomer and salts thereof in an amount of zero or more, 0.5 wt% or more, 0.8 wt% or more, 1 wt% or more, 1.2 wt% or more, 1.5 wt% or more, 1.8 wt% or more, or even 2 wt% or more, and at the same time, 10 wt% or less, 7 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, or even 2.5 wt% or less, based on the weight of the emulsion polymer.

[0030] Emulsion polymers useful in the present application can include structural units of one or more ethylenically unsaturated functional monomers different from the monomers described above, the one or more ethylenically unsaturated functional monomers having one or more functional groups selected from ureido, amide, amino, silane, hydroxyl, or combinations thereof. These ethylenically unsaturated functional monomers can include, for example, amino-functional monomers such as dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylate; monomers bearing amide functional groups such as acrylamide and methacrylamide; vinyl trialkoxysilanes such as vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(2-methoxyethoxy)silane, vinyl dimethylethoxysilane vinyl methyl diethoxysilane, or (meth)acryloyloxyalkyl trialkoxysilanes such as (meth)acryloyloxyethyl trimethoxysilane and (meth)acryloyloxypropyl trimethoxysilane; ureido-functional monomers; hydroxyl-functional monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 3-hydroxybutyl methacrylate; or mixtures thereof. Preferably, the ethylenically unsaturated functional monomer is a ureido-functional monomer. As used herein, the term “ureido-functional monomer” refers to an ethylenically unsaturated compound that includes a cyclic ureido group (i.e., an imidazolidin-2-one group). The ureido-functional monomer can include cyclic ureido-containing alkyl esters of (meth)acrylic acid. Examples of suitable ureido-functional monomers include N-(2-methacrylamidoethyl) ethylene urea, N-(2-methacryloyloxyethyl) ethylene urea, N-(maleic acid diethyl ester) ethylene urea, or mixtures thereof. The preferred ureido-functional monomer is N-(2-methacryloyloxyethyl) ethylene urea. The emulsion polymer can include structural units of the ethylenically unsaturated functional monomer in an amount of zero or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, or even 0.7 wt% or more, and at the same time 3 wt% or less, 2.5 wt% or less, 2 wt% or less, 1.5 wt% or less, 1.1 wt% or less, 1 wt% or less, 0.9 wt% or less, or even 0.8 wt% or less, based on the weight of the emulsion polymer.

[0031] Emulsion polymers useful in the present application can include structural units of one or more additional ethylenically unsaturated non-ionic monomers different from the (meth)acrylic cycloalkyl ester, acetoacetoxy, or acetoacetamide functional monomers and the ethylenically functional monomers. “Non-ionic monomer” herein refers to a monomer that does not carry an ionic charge between pH = 1-14. The ethylenically unsaturated non-ionic monomers can include C1-C 24 - alkyl esters such as (meth)acrylic acid C4-C24 - alkyl ester, styrene, substituted styrene, (meth)acrylonitrile, or mixtures thereof. The (meth)acrylic acid Ci-C 24 alkyl ester refers to alkyl esters of (meth)acrylic acid containing an alkyl group having 1 to 24 carbon atoms. Examples of suitable additional ethylenically unsaturated nonionic monomers include methyl methacrylate, (meth)acrylic acid ethyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid t-butyl ester, (meth)acrylic acid lauryl ester, or mixtures thereof. The additional ethylenically unsaturated nonionic monomer can include one or any combination of more than one type of ethylenically unsaturated nonionic monomer selected from styrene, substituted styrene, (meth)acrylic acid C4-C 24 alkyl ester, or mixtures thereof. The emulsion polymer can include structural units of additional ethylenically unsaturated nonionic monomers in an amount of 42 wt.% or more, 45 wt.% or more, 50 wt.% or more, 55 wt.% or more, or even 60 wt.% or more, and at the same time 94 wt.% or less, 90 wt.% or less, 85 wt.% or less, 80 wt.% or less, 75 wt.% or less, 70 wt.% or less, or even 65 wt.% or less, based on the weight of the emulsion polymer.

[0032] The emulsion polymer useful in the present application can include structural units of one or more polymerizable surfactants. The polymerizable surfactant can contain at least one carbon-carbon double bond. The polymerizable surfactant can have the structure of Formula (I),

[0033]

[0034] wherein R1is a phenyl group or wherein R is an alkylene group; m1is an integer from 0 to 4, for example, 0, 1, 2, 3, or 4, preferably 1 to 3; R2is an alkyl or substituted alkyl group, preferably a C1-C4alkyl or substituted C1-C4alkyl group; m2is 0 or 1; R3is hydrogen or a C1-C 20 or a C1-C4alkyl group, such as methyl; R4is hydrogen or a C1-C 20 or a C1-C4alkyl group, such as methyl; A represents an alkylene group or substituted alkylene group having 2 to 4 carbon atoms; n represents the average addition mole number of alkylene oxide and is an integer in the range of 0 to 1,000, 1 to 100, 2 to 60, 3 to 50, or 4 to 40; and X represents hydrogen or an anionic hydrophilic group selected from the group consisting of -(CH2) a -SO3M, -(CH2) b-COOM, -P03M2, -P(Z)02M, or -CO-CH2-CH(S03M)-COOM, wherein a and b are each independently an integer from 0 to 4, Z represents a residue obtained by removing X from general formula (I), and each M represents hydrogen, an alkali metal atom, an alkaline earth metal atom, an ammonium residue, or a alkanolamine residue.

[0035] In formula (I), R1may be wherein R can be an alkylene group having 1 to 4 carbon atoms, preferably having 2 to 3 carbon atoms, for example, -CH2-, -CH(CH3)-, or -C(CH3)2-. A preferred R1is Preferably, m1is 2 or 3. In formula (I), A can be an ethylene group (-CH2CH2-). n can be an integer in the range of 4 to 40 or 5 to 20. A preferred X is -S03M. Preferably, M is NH4 + Specific examples of polymerizable surfactants can include the following structures:

[0036] wherein m1and n are as defined above in formula (I), and M is Li + , Na + , K + , or NH4 + Suitable commercially available polymerizable surfactants can include Hitenol AR-1025 from DKS Co., Ltd. The emulsion polymer useful in the present invention can include structural units of polymerizable surfactants in an amount of zero or more, 0.5 wt% or more, 0.7 wt% or more, 0.9 wt% or more, 1.1 wt% or more, or even 1.2 wt% or more, and at the same time, 10 wt% or less, 7 wt% or less, 5 wt% or less, 3 wt% or less, 2 wt% or less, 1.5 wt% or less, or even 1.3 wt% or less, based on the weight of the emulsion polymer.

[0037] The emulsion polymer useful in the present invention can optionally include structural units of one or more multiethylenically unsaturated monomers different from the monomers described above, including di-, tri-, tetra-, or higher multi-functional ethylenically unsaturated monomers. Examples of suitable multiethylenically unsaturated monomers include butadiene, (meth)allyl acrylate, divinyl benzene, ethylene glycol dimethacrylate, butanediol dimethacrylate, or mixtures thereof. The emulsion polymer can include structural units of multiethylenically unsaturated monomers in an amount of zero to 5 wt%, for example, 3 wt% or less, 2 wt% or less, 1 wt% or less, 0.5 wt% or less, 0.1 wt% or less, or even zero, based on the weight of the emulsion polymer.

[0038] Based on the weight of the emulsion polymer, the emulsion polymer useful in the present application can include 10 to 25 weight percent of structural units of (meth)acrylic cycloalkyl ester; 1.5 to 4 weight percent of structural units of acetoacetoxy or acetoacetamide functional monomer; 1.5 to 4 weight percent of structural units of phosphorous acid containing monomer, salts thereof, or mixtures thereof; and structural units of additional ethylenically unsaturated non-ionic monomer; and optionally zero to 3 weight percent of structural units of ethylenically unsaturated functional monomer.

[0039] The total weight concentration of structural units in the emulsion polymer is equal to 100 percent. The type and amount of monomers described above for making the emulsion polymer can be selected to provide an emulsion polymer having a glass transition temperature (Tg) suitable for various applications. The Tg of the emulsion polymer can be 0°C or higher, 5°C or higher, 10°C or higher, 15°C or higher, 20°C or higher, 25°C or higher, or even 30°C or higher, and at the same time 60°C or lower, 55°C or lower, 50°C or lower, 47°C or lower, 44°C or lower, or even 40°C or lower, as calculated by the Fox equation. g may be 0°C or higher, 5°C or higher, 10°C or higher, 15°C or higher, 20°C or higher, 25°C or higher, or even 30°C or higher, and at the same time 60°C or lower, 55°C or lower, 50°C or lower, 47°C or lower, 44°C or lower, or even 40°C or lower, as calculated by the Fox equation.

[0040] The emulsion polymer useful in the present application can have a number average molecular weight (Mn) of 10,000 g / mol or more, for example, 15,000 g / mol or more, 20,000 g / mol or more, 25,000 g / mol or more, 30,000 g / mol or more, 35,000 g / mol or more, 40,000 g / mol or more, 45,000 g / mol or more, 50,000 g / mol or more, or even 55,000 g / mol or more, and at the same time 1,000,000 g / mol or less, 800,000 g / mol or less, 600,000 g / mol or less, 400,000 g / mol or less, 300,000 g / mol or less, 200,000 g / mol or less, 150,000 g / mol or less, 120,000 g / mol or less, 100,000 g / mol or less, 80,000 g / mol or less, 70,000 g / mol or less, 65,000 g / mol or less, or even 60,000 g / mol or less. The molecular weight of the emulsion polymer can be measured by gel permeation chromatography (GPC) as described in the Examples section below.

[0041] Emulsion polymers useful in the present application can be prepared by emulsion polymerization of a mixture of monomers ("monomer mixture") described above. The total concentration of monomers in the monomer mixture used to prepare the emulsion polymer is equal to 100%. For each monomer, the weight concentration of the monomer in the monomer mixture (i.e., based on the total weight of the monomer mixture) is the same as the weight concentration of the structural units of such monomer in the emulsion polymer described above (i.e., based on the weight of the emulsion polymer). The monomer mixture can be added neat or in the form of an emulsion in water; or added in one or more addition forms or continuously, linearly, or non-linearly over the reaction period to prepare the emulsion polymer. The monomer mixture can be added neat or in the form of an emulsion in water; or added in one or more addition forms or continuously, linearly, or non-linearly over the reaction period to prepare the polymer. The temperature suitable for the free radical polymerization process can be less than 100°C, in the range of 10°C to 99°C, or in the range of 50°C to 90°C. One or more surfactants, preferably polymerizable surfactants, can be used to prepare the polymer.

[0042] One or more free radical initiators can be used in the polymerization process. The polymerization process can 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, peroxodisulfuric acid and salts thereof; potassium permanganate and ammonium or alkali metal salts of peroxydisulfates. The free radical initiator can be used typically at a level of 0.01 to 3.0 wt% based on the total weight of monomers. In the polymerization process, a redox system comprising the above initiators and a suitable reducing agent can be used. Examples of suitable reducing agents include sodium formaldehyde sulfoxylate, ascorbic acid, erythorbic acid, alkali metal and ammonium salts of sulfur-containing acids (such as sodium sulfite, bisulfite, thiosulfate, hydrosulfite, sulfide, hydrosulfide, or dithionite), formamidine sulfinic acid, acetone bisulfite, glycolic acid, hydroxymethyl sulfonic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid, and salts of the foregoing acids. Metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium, or cobalt can be used to catalyze the redox reaction. Metal chelating agents can optionally be used.

[0043] One or more chain transfer agents can be used during polymerization to control the molecular weight of the emulsion polymer. Examples of suitable chain transfer agents include 3-mercaptopropionic acid, 3-mercapto propionic acid methyl ester, 3-mercapto propionic acid butyl ester, n-dodecyl mercaptan, n-hexadecane thiol, t-dodecyl mercaptan, n-octadecane thiol, benzene thiol, nonadecane thiol, hydroxyl group containing thiols such as hydroxyethyl thiol, mercaptopropionic acid, and mixtures thereof. The chain transfer agent can be used in an amount of zero to 2 wt.%, for example, 1.5 wt.% or less, 1 wt.% or less, 0.5 wt.% or less, 0.3 wt.% or less, 0.2 wt.% or less, or even 0.15 wt.% or less, based on the total weight of the monomers (i.e., the monomer mixture) used to make the emulsion polymer.

[0044] After completion of polymerization, the obtained aqueous dispersion can be neutralized to a pH value, for example, at least 5, 6 to 12, 7 to 10, or 8 to 9, by one or more bases as neutralizing agents. The base can cause partial or complete neutralization of ionic or potentially ionic groups of the emulsion polymer. Examples of suitable bases include ammonia; alkali metal or alkaline earth metal compounds, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, sodium carbonate; primary, secondary, and tertiary amines, such as triethylamine, ethylamine, propylamine, monoisopropylamine, monobutylamine, hexylamine, ethanolamine, diethylamine, dimethylamine, tributylamine, triethanolamine, dimethoxyethylamine, 2-ethoxyethylamine, 3-ethoxypropylamine, dimethylethanolamine, diisopropyl ethanolamine, morpholine, ethylenediamine, 2-diethylaminoethylamine, 2,3-diaminopropane, 1,2- propanediamine, neopentanediamine, dimethylaminopropylamine, hexamethylenediamine, 4,9-dioxadodecane-1,12-diamine, polyethyleneimine, or polyvinylamine; aluminum hydroxide; or mixtures thereof. The emulsion polymer particles in the aqueous dispersion can have a particle size of 50 nanometers (nm) or greater, 80 nm or greater, or even 90 nm or greater, and at the same time 500 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-90Plus particle size analyzer.

[0045] The aqueous polymer composition of the present application can comprise the emulsion polymer in an amount of 92.2 wt% or more, 92.3 wt% or more, 92.4 wt% or more, 92.5 wt% or more, 92.6 wt% or more, 92.7 wt% or more, 92.8 wt% or more, 93 wt% or more, 93.2 wt% or more, 93.5 wt% or more, 93.8 wt% or more, 94 wt% or more, 94.2 wt% or more, 94.5 wt% or more, 94.8 wt% or more, or even 95 wt% or more, and at the same time 99.3 wt% or less, 99.2 wt% or less, 99.1 wt% or less, 99 wt% or less, 98.8 wt% or less, 98.5 wt% or less, 98.2 wt% or less, or even 98 wt% or less, based on the total dry weight of the emulsion polymer and the aqueous resin described below.

[0046] The aqueous polymer composition of the present application further comprises one or more aqueous resins containing at least one fatty acid ester segment that are different from the emulsion polymer described above. "Aqueous resin" herein means a resin that can be dissolved in water or can be dispersed in water. The aqueous resins useful in the present application can be aqueous epoxy esters, unsaturated fatty acid ester-modified acrylic copolymers, or mixtures thereof.

[0047] The aqueous epoxy esters used in this invention may contain one or more fatty acid ester segments. The fatty acid ester segments can be formed by reacting an epoxy compound with a fatty acid, preferably an unsaturated fatty acid. The aqueous epoxy ester may comprise the reaction product of an epoxy compound with an unsaturated fatty acid and optionally another compound containing a carboxylic acid group, different from the unsaturated fatty acid. One or more solvents, such as butanol, dimethylbenzene, 2-butoxy-1-ethanol monobutyl ether, ethylene glycol monoethyl ether, or mixtures thereof, are typically used to dilute the reaction product. The epoxy group in the epoxy compound may react with the carboxylic acid group in the unsaturated fatty acid through a condensation reaction to form at least one unsaturated fatty acid ester segment (i.e., the residue of the unsaturated fatty acid after esterification) in the aqueous epoxy ester. The epoxy compound may be an aliphatic, aromatic, or alicyclic epoxy compound or mixtures thereof. Suitable epoxy compounds may include, for example, diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of a diol, diglycidyl ether of polyethylene glycol, diglycidyl ether of polypropylene glycol, or mixtures thereof. Unsaturated fatty acids can contain 6 to 36 carbon atoms, 6 to 30 carbon atoms, 8 to 24 carbon atoms, or 8 to 18 carbon atoms. Examples of suitable unsaturated fatty acids include soybean oleic acid, lauric acid, coconut oil fatty acids, tung oil fatty acids, linseed oil fatty acids, dehydrated castor oil fatty acids, their dimers or oligomers, or mixtures thereof. When the unsaturated fatty acid used to prepare the aqueous epoxy ester is a monocarboxylic acid, the resulting epoxy ester can include segments having the structure of formula (IIa):

[0048] C na H ma O2-(IIa),

[0049] Where na is an integer from 6 to 18, and ma = 2na-3, 2na-5, or 2na-7.

[0050] When the unsaturated fatty acid used to prepare the aqueous epoxy ester is an unsaturated fatty acid dimer, the resulting epoxy ester may include segments having the structure of formula (IIb):

[0051] -O2C-C nb H mb -CO2-(IIb),

[0052] Where nb is an integer from 10 to 36, and mb = 2nb-4, 2nb-6, 2nb-8, 2nb-10 or 2nb-12.

[0053] Additional carboxylic acid group-containing compounds that can be used to make the epoxy ester can include ethylenically unsaturated carboxylic acid monomers, which can be a monocarboxylic acid or a dicarboxylic acid, a polyacrylic acid, a carboxylic acid group-containing polyacrylate, or mixtures thereof. The carboxylic acid monomers can include the carboxylic acid monomers described in the emulsion polymer section above, in particular (meth)acrylic acid. Preferably, the epoxy ester is a (meth)acrylic functional epoxy ester. In the reaction to form the epoxy ester, the molar ratio of carboxylic acid groups to epoxy groups in the reactants can be in the range of 10: 1 to 1 : 1, 5: 1 to 1 : 1, 2: 1 to 1 : 1, 1.8: 1 to 1 : 1, 1.5: 1 to 1 : 1, or 1.2: 1 to 1 : 1. The epoxy ester resin can also be modified with an alpha, beta-ethylenically unsaturated dicarboxylic acid and / or an anhydride thereof by addition reaction to the double bonds in the epoxy ester (i.e., forming carboxylic acid groups), and can then also be neutralized with ammonia and / or an amine to a pH value greater than 9 or 9.5 or higher. Suitable alpha, beta-ethylenically unsaturated dicarboxylic acids can include, for example, maleic anhydride, fumaric acid, itaconic acid, or mixtures thereof. Suitable amines can include, for example, ethanolamine, triethanolamine, dimethylethanolamine, 1,6-diaminohexane, ethylenediamine, triethylethylenediamine, phenylenediamine, or mixtures thereof. The obtained aqueous epoxy ester can include a solvent typically used in the reaction to make the aqueous epoxy ester, for example, in an amount of 5 wt% or more, 10 wt% or more, 15 wt% or more, 17 wt% or more, or even 19 wt% or more, and at the same time 30 wt% or less, 25 wt% or less, or even 20 wt% or less, based on the wet weight of the aqueous epoxy ester.

[0054] The aqueous resin useful in the present application can include an unsaturated fatty ester modified acrylic copolymer (hereinafter "modified acrylic copolymer"). Such copolymers can be prepared by polymerization of an unsaturated fatty ester and one or more acrylic monomers including acrylic acid, methacrylic acid, or mixtures thereof. The modified acrylic copolymer can include structural units of acrylic acid, methacrylic acid, or mixtures thereof in an amount of 20 wt.% or more, 30 wt.% or more, 40 wt.% or more, 50 wt.% or more, 60 wt.% or more, or even 70 wt.% or more, and at the same time 99 wt.% or less, 95 wt.% or less, 90 wt.% or less, or even 85 wt.% or less, based on the weight of the modified acrylic copolymer. "Unsaturated fatty ester" herein refers to the ester product of an unsaturated fatty acid and an alcohol. The alcohol can be any mono-, di-, or polyhydric alcohol capable of condensing with the unsaturated fatty acid to form the corresponding unsaturated fatty ester. Typically, the alcohol contains at least one carbon atom. Typically, the alcohol contains less than 20 carbon atoms, less than 12 carbon atoms, or less than 8 carbon atoms. The carbon atoms can be arranged in a linear or branched structure, and can be substituted with a variety of substituents, such as alkyl, cycloalkyl, monocyclic aromatic, aralkyl, alkaryl, hydroxyl, halogen, ether, ester, aldehyde, and ketone substituents. Preferably, the alcohol is a linear or branched C1-C 12 alkanol. A preferred alcohol is the trihydric alcohol glycerol, the fatty acid ester of which is known as "glycerides". Other preferred alcohols include methanol and ethanol. The unsaturated fatty ester useful in the present application can be obtained from oils such as flaxseed, tung, castor, dehydrated castor, soybean, tall, sunflower, and corn. Preferably, the unsaturated fatty ester is derived from C8-C 25 unsaturated fatty acid segment and C1-C 12Alcohol Segments. Suitable unsaturated fatty acid esters can include mono-unsaturated fatty acid esters formed from palmitoleic acid, oleic acid, or hexanoic acid; di-unsaturated fatty acid esters formed from linoleic acid; tri-unsaturated fatty acid esters formed from linolenic acid or eleostearic acid, or mixtures thereof. Preferred fatty acid esters are rapeseed oil, castor oil, sulfated castor oil, soybean oil, palm oil, olive oil, or mixtures thereof. The modified acrylic copolymer can include the following amounts of structural units of unsaturated fatty acid esters, based on the weight of the modified acrylic copolymer: 1 wt% to 50 wt%, 3 wt% to 45 wt%, 6 wt% to 40 wt%, or 10 wt% to 30 wt%. The acrylic monomers that can be used to make the modified acrylic copolymer can also include one or more multi-ethylenically unsaturated monomers. The multi-ethylenically unsaturated monomers can include the multi-ethylenically unsaturated monomers described in the emulsion polymer section above, in particular, allyl methacrylate. The resulting modified acrylic copolymer can include the following amounts of structural units of multi-ethylenically unsaturated monomers, based on the weight of the modified acrylic copolymer: zero to 10 wt%, 0.05 wt% to 5 wt%, 0.1 wt% to 3 wt%, or 0.15 wt% to 2 wt%. The polymerization process used to make the modified acrylic copolymer can be carried out as an emulsion polymerization as described in the emulsion polymer section above.

[0055] The aqueous resins useful in the present application can have a number average molecular weight of 20,000 g / mol or less, for example, 19,000 g / mol or less, 18,000 g / mol or less, 17,000 g / mol or less, 16,000 g / mol or less, 15,000 g / mol or less, 14,000 g / mol or less, 13,000 g / mol or less, 12,000 g / mol or less, 11,000 g / mol or less, 10,000 g / mol or less, 9,000 g / mol or less, 8,000 g / mol or less, 7,000 g / mol or less, 6,000 g / mol or less, or even 5,000 g / mol or less. The molecular weight can be measured by GPC as described in the Examples section below.

[0056] The aqueous polymer composition of the present invention can comprise the aqueous resin in an amount of 0.7 dry wt.% or more, 0.8 dry wt.% or more, 0.9 dry wt.% or more, 1.0 dry wt.% or more, 1.2 dry wt.% or more, 1.5 dry wt.% or more, 1.8 dry wt.% or more, or even 2 dry wt.% or more, and at the same time 7.8 dry wt.% or less, 7.7 dry wt.% or less, 7.6 dry wt.% or less, 7.5 dry wt.% or less, 7.4 dry wt.% or less, 7.3 dry wt.% or less, 7.2 dry wt.% or less, 7 dry wt.% or less, 6.8 dry wt.% or less, 6.5 dry wt.% or less, 6.2 dry wt.% or less, 6 dry wt.% or less, 5.8 dry wt.% or less, 5.5 dry wt.% or less, 5.2 dry wt.% or less, or even 5 dry wt.% or less, based on the total dry weight of the emulsion polymer and the aqueous resin.

[0057] The aqueous polymer composition of the present invention can comprise the ammonia and / or amine in an amount of 0.005 wt.% or more, 0.01 wt.% or more, 0.02 wt.% or more, 0.03 wt.% or more, or even 0.04 wt.% or more, and at the same time 5 wt.% or less, 4 wt.% or less, 2 wt.% or less, 1 wt.% or less, 0.8 wt.% or less, or even 0.7 wt.% or less, based on the total dry weight of the emulsion polymer and the aqueous resin. The aqueous polymer composition further comprises, for example, water in an amount of 30 wt.% to 90 wt.%, 40 wt.% to 80 wt.%, 50 wt.% to 70 wt.%, or 55 wt.% to 60 wt.%, based on the total weight of the aqueous polymer composition.

[0058] The aqueous polymer composition of the present invention can optionally comprise one or more driers. A "drier" herein refers to the reaction product of a metal hydroxide and a fatty acid. The drier can facilitate crosslinking of the aqueous epoxy ester. Suitable driers can include, for example, cobalt 2-ethylhexanoate, cobalt naphthenate, manganese naphthenate, or mixtures thereof. The aqueous polymer composition can comprise the drier in an amount of 15 wt.% or less, 12 wt.% or less, 10 wt.% or less, 9 wt.% or less, 8 wt.% or less, 7 wt.% or less, 5 wt.% or less, or even zero, based on the dry weight of the aqueous epoxy ester. Preferably, the aqueous polymer composition is substantially free of the drier, for example, in an amount of less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than 1 wt.%, less than 0.5 wt.%, or even zero, based on the dry weight of the aqueous epoxy ester.

[0059] The present invention also relates to a method of making the aqueous polymer composition by mixing the emulsion polymer (typically in an aqueous dispersion) with the aqueous resin. This method can provide easy processability and application by simply blending the emulsion polymer and the aqueous resin.

[0060] The aqueous polymer composition of the present invention is particularly useful as a binder in coating applications. The present invention also relates to a coating composition comprising the aqueous polymer composition and optionally one or more pigments. The coating composition can comprise the aqueous polymer composition in an amount of 5 wt% to 95 wt%, 10 wt% to 80 wt, or 20 wt% to 70 wt% based on the total weight of the coating composition. "Pigment" herein refers to a material that is capable of substantially contributing to the opacity or hiding power of the coating composition. Typically, such materials have a refractive index greater than 1.8. Inorganic pigments typically include metal oxides. Examples of suitable pigments include titanium dioxide (Ti02), carbon black, iron oxide, zinc sulfide, lemon chrome yellow, iron oxide black, or mixtures thereof. Organic pigments typically include Prussian blue, organic pigment yellow, organic pigment red, anticorrosive pigments such as zinc phosphate, zinc molybdate, zinc oxide, aluminum tripolyphosphate, zinc molybdate phosphate, or modified zinc phosphate; or mixtures thereof. Carbon black can include acetylene black, channel black, furnace black, lamp black, and thermal black. The preferred pigment is carbon black, barium sulfate, zinc phosphate, or modified zinc phosphate, or mixtures thereof. More preferably, the pigment is carbon black.

[0061] The coating composition of the present invention can comprise one or more extenders. "Extender" herein refers to a particulate inorganic material having a refractive index less than or equal to 1.8 and greater than 1.3. Examples of suitable extenders include barium sulfate, talc, calcium carbonate, clay, calcium sulfate, aluminum silicate, silicates, zeolites, mica, diatomaceous earth, solid or hollow glass, ceramic beads, nepheline syenite, feldspar, diatomite, calcined diatomite, talc (hydrous magnesium silicate), silica, alumina, kaolin, smectite, perlite, barite, wollastonite, opacifying polymers such as ROPAQUE Ultra E (ROPAQUE is a trademark of The Dow Chemical Company) or mixtures thereof. The coating composition can have a pigment volume concentration (PVC) of zero to 55%, 5% to 40%, or 10% to 35%. PVC can be determined by the following equation: PVC = [volume of pigment / dry volume of coating composition] x 100%. TM (颜料+增量剂) (涂料组合物)

[0062] ​​​The coating compositions of the present invention may contain one or more defoamers. As used herein, "defoamer" refers to a chemical additive that reduces and prevents foam formation. Defoamers may be silicone-based defoamers, mineral oil-based defoamers, ethylene oxide / propylene oxide defoamers, alkyl polyacrylates, and mixtures thereof. Suitable commercially available defoamers may include, for example, TEGO Airex 901W, TEGO Airex 902W, and TEGO Foamex 1488 polyether silicone copolymer emulsions available from TEGO, and BYK-022 and BYK-024 silicone deformants available from BYK, and mixtures thereof. Based on the total weight of the coating composition, the defoamer may typically be present in amounts of 0 to 5 wt%, 0.05 wt% to 3 wt%, or 0.1 wt% to 2 wt%.

[0063] The coating compositions of the present invention may contain one or more thickeners, also known as "rheology modifiers". Thickeners may include polyvinyl alcohol (PVA), clay materials, acid derivatives, acid copolymers, urethane associative thickeners (UAT), polyether urea polyurethane (PEUPU), polyether polyurethane (PEPU), or mixtures thereof. Examples of suitable thickeners include alkali-swellable emulsions (ASE), such as sodium or ammonium-neutralized acrylic polymers; hydrophobically modified alkali-swellable emulsions (HASE), such as hydrophobically modified acrylic copolymers; associative thickeners, such as hydrophobically modified ethoxylated urethane (HEUR); and cellulose thickeners, such as methyl cellulose ether, hydroxymethyl cellulose (HMC), hydroxyethyl cellulose (HEC), hydrophobically modified hydroxyethyl cellulose (HMHEC), sodium carboxymethyl cellulose (SCMC), sodium carboxymethyl 2-hydroxyethyl cellulose, 2-hydroxypropyl methylcellulose, 2-hydroxyethyl methylcellulose, 2-hydroxybutyl methylcellulose, 2-hydroxyethyl ethyl cellulose, and 2-hydroxypropyl cellulose. Preferably, the thickener is HEUR. Based on the total weight of the coating composition, the thickener may be present in amounts of 0 to 5 wt%, 0.05 wt% to 3 wt%, or 0.1 wt% to 1 wt%.

[0064] The coating compositions of the present invention may contain one or more wetting agents. As used herein, "wetting agent" refers to a chemical additive that reduces the surface tension of the composition, thereby facilitating diffusion or penetration across or into the substrate surface. The wetting agent may be anionic, amphoteric, or nonionic polycarboxylic acid esters. Suitable commercially available wetting agents may include, for example, SURFYNOL 104 and SURFYNOLTG nonionic wetting agents based on actacetylenic diols from Evonik; BYK-190, TEGO-750W, and TEGO-755W solutions of high molecular weight block polymers with pigment affinity groups from BYK and Evonik, respectively; BYK-346 and BYK-349 polyether-modified siloxanes from BYK; or mixtures thereof. Based on the total weight of the coating composition, the wetting agent may be present in amounts of 0 to 5 wt%, 0.05 wt% to 3 wt%, or 0.1 wt% to 2 wt%.

[0065] The coating compositions of the present invention may contain one or more coalescing agents. As used herein, "coalescing agent" refers to a slowly evaporating solvent that fuses polymer particles into a continuous film under ambient conditions. Examples of suitable coalescing agents 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 coalescing agents include dipropylene glycol n-butyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, n-butyl ether, or mixtures thereof. Based on the total weight of the coating composition, the coalescing agent may be present in amounts of 0 to 15% by weight, 0.5% to 8% by weight, or 2% to 5% by weight.

[0066] The coating compositions of the present invention may contain one or more dispersants. The dispersant may be polyacrylic acid or polymethacrylic acid or maleic anhydride having various monomers (such as styrene, acrylates or methacrylates, diisobutylene and other hydrophilic or hydrophobic comonomers); their salts; or mixtures thereof. Based on the total weight of the coating composition, the dispersant may be present in amounts of 0 to 5% by weight, 0.05% to 3% by weight, or 0.1% to 1% by weight.

[0067] In addition to the components described above, the coating compositions of the present invention may contain any one or a combination of the following additives: buffers, neutralizers, humectants, fungicides, insecticides, anti-skinning agents, colorants, flow agents, antioxidants, plasticizers, leveling agents, tackifiers, flash rust inhibitors, and abrasives. These additives may be present in amounts ranging from 0 to 10% by weight or in combinations of 0.1% to 2% by weight, based on the total weight of the coating composition. The coating compositions may also contain water in amounts ranging from 30% to 90%, 40% to 80%, or 50% to 70% by weight of the coating composition.

[0068] The coating compositions of the present invention can be prepared by mixing an aqueous polymer composition with pigments and optionally other components described above. The components in the coating composition can be mixed in any order to provide the coating compositions of the present invention. Any of the optional components described above can also be added to the coating composition during or before mixing to form the coating composition. Pigments and / or extenders are preferably mixed with dispersants to form a slurry of pigments and / or extenders.

[0069] The coating compositions of this invention can be applied to and adhere to a variety of substrates. Examples of suitable substrates include wood, metal, plastic, foam, stone, elastic substrates, glass, textiles, concrete, or cement substrates. The coating compositions are suitable for a wide range of applications, such as marine protective coatings, general industrial finishes, metal protective coatings, automotive coatings, road marking coatings, exterior insulation and finishing systems (EIFS), wood coatings, coil coatings, plastic coatings, can coatings, architectural coatings, and civil engineering coatings. The coating compositions are particularly suitable for metal protective coatings. The coating compositions can be used as primers, topcoats, single-coat paints for direct contact with metal, or in combination with other coatings to form multilayer coatings.

[0070] The coating compositions of the present invention can be applied to a substrate by existing methods including brushing, dipping, rolling, and spraying. Aqueous compositions are preferably applied by spraying. Standard spraying techniques and equipment, such as air atomization spraying, air spraying, airless spraying, high-volume low-pressure spraying, and electrostatic spraying (e.g., electrostatic bell application), as well as manual or automated methods, can be used. After the coating compositions of the present invention are applied to the substrate, the coating compositions can be dried at a temperature in the range of 0°C to 35°C or at a high temperature, for example, 35°C to 240°C, to form a film (i.e., a coating).

[0071] The coating compositions of the present invention can provide coatings with improved corrosion resistance prepared therefrom. The present invention also provides a method for improving the corrosion resistance of a susceptible substrate (such as a metal). The method comprises: providing a susceptible substrate, applying a coating composition to the susceptible substrate (i.e., coating the coating composition onto the susceptible substrate), and drying the coating composition to form a coated substrate. The corrosion resistance is characterized by a maximum creep of 2 mm at the scribing point, preferably 1.7 mm or less, 1.5 mm or less, 1.2 mm or less, or even 1 mm or less, after exposure to salt spray for at least 130 hours, at a dry film thickness of 40 micrometers (μm) to 60 μm. The coating compositions of the present invention can also provide coatings with good early water resistance, as indicated by a foaming grade of 10, 8F, or 6F and a rust grade of 10, 9P, 9S, or 9G. Corrosion resistance and early water resistance can be measured according to the test methods described in the Examples section below. The present invention also relates to an article prepared by this method. The present invention also relates to a method for preparing a coating. The method may include applying a coating composition to a substrate and drying the applied coating composition to form a coating having the properties defined above.

[0072] Compared to conventional epoxy ester coating compositions (typically containing epoxy ester as the sole binder), the coating compositions of the present invention, which contain an aqueous polymer composition as a binder, dry much faster, enabling higher product efficiency. For example, when the coating composition is applied to a substrate and dried for 1 to 6 hours, e.g., 2 hours or less, the resulting two coated surfaces can be stacked or placed in contact with each other without coating damage when separating the two coated surfaces. In contrast, conventional epoxy ester coating compositions require at least 24 hours of drying before the coated surfaces can be stacked.

[0073] Example

[0074] Some embodiments of the invention will now be described in the following examples, wherein all parts and percentages are by weight unless otherwise stated.

[0075] Cyclohexyl methacrylate (CHMA) is available from BASF.

[0076] Styrene (ST) is available from Langyuan Chemical Co., Ltd.

[0077] Sulfated castor oil is available from Hydrior AG.

[0078] 2-Ethylhexyl acrylate (2-EHA) is available from Dow Chemical Company.

[0079] Methacrylic acid (MAA), acrylic acid (AA), allyl methacrylate (ALMA), isoascorbic acid (IAA), n-dodecyl mercaptan (n-DDM), and NaNO2 anti-flash rust additive are available from Sinopharm Chemical Reagent Co., Ltd.

[0080] Ethyl phosphate methacrylate (PEM) is available from Solvay.

[0081] N-(2-Methacryloyloxyethyl)vinylurea (MEUR) is available from Evonik.

[0082] Acetylacetyloxyethyl methacrylate (AAEM) is available from Eastman.

[0083] DISPERBYK-190 dispersant and DISPERBYK-022 defoamer are available from BYK.

[0084] Printex 4 carbon black, used as a pigment, is available from Orion.

[0085] BS-115BaSO4 packing material is available from GuangFu Jiancai Co., Ltd.

[0086] OROTAN available from Dow Chemical Company TM 731A dispersant is a hydrophobic polycarboxylic acid copolymer.

[0087] Both TEGO Airex 901w defoamer, used as a wetting agent, and TEGO Twin 4100 siloxane-based Gemini surfactant are available from Evonik.

[0088] AMP 95 2-amino-2-methyl-1-propanol, available from Angus, can be used as a neutralizing agent.

[0089] Texanol ester alcohol (3-hydroxy-2,2,4-trimethylpentyl isobutyrate), available from Eastman, can be used as a coalescing agent.

[0090] ACRYSOL TM RM-8W nonionic urethane rheology modifier is available from Dow Chemical Company.

[0091] YG-EA670 epoxy ester resin (solids content: 70%-75%), available from Yangguang HuiDe (China), includes waterborne epoxy ester resin (M... n (1,954 g / mol).

[0092] RETAN TM 540 sulfated castor oil modified acrylic latex (solid content: 40%) (Mn: 4,687 g / mol) was purchased from Dow Chemical Company.

[0093] OROTAN, RETAN, and ACRYSOL are trademarks of Dow Chemical Company.

[0094] The following standard analytical equipment and methods were used in the embodiments to determine the properties and characteristics described herein:

[0095] Solids content

[0096] The solids content of aqueous dispersions or aqueous resins is measured as follows: Weigh 0.7 ± 0.1 g of sample (the wet weight of the sample is expressed as "W1"), place the sample in an aluminum pan (the weight of the aluminum pan is expressed as "W2") in an oven at 150°C for 25 minutes, and then cool to room temperature (20°C-25°C) and weigh the aluminum pan containing the dried sample, where the total weight is expressed as "W3". "W3-W2" refers to the dry or solid weight of the sample. The solids content is calculated by (W3-W2) / W1*100%.

[0097] Salt fog resistance test

[0098] The test coating composition was applied to Q panels using a 150 μm applicator. The resulting coated panels were first dried at 60°C for 20 minutes, and then dried at room temperature and 50% relative humidity (RH) for 7 days. “X”-shaped scratches were created on the dry film of the coated panels by cutting through it with a razor blade. The prepared coated panels were then placed in a salt spray chamber according to ASTM B117 (2011) by exposing them to a salt spray environment (5% sodium chloride mist). After 130 hours of salt spray treatment, the panels were removed from the salt spray chamber and washed with deionized (DI) water. Blistering and rust creep along the scratch marks were then measured. Creep was the width of the largest blister or rust starting from either side of the scratch mark. A passing test was a maximum creep of 2 mm after 130 hours of salt spray testing.

[0099] Early water resistance

[0100] The coated panels were prepared by applying the test coating composition to Q panels (cold-rolled steel) using a 150 μm applicator, and then drying the coating composition at room temperature and 50% RH for 2 hours. The resulting coated panels were then immersed in DI water at room temperature for 7 days. The degree of rust and blistering on the coated panels was then evaluated and recorded according to ASTM D610 (2001) and ASTM D714-02 (2010), respectively. Panels with a blistering grade of 10, 8F, or 6F and a rust grade of 10, 9P, 9S, or 9G were acceptable.

[0101] GPC analysis of waterborne epoxy ester and emulsion polymer

[0102] GPC analysis is generally performed using an Agilent 1200. The sample is dissolved in a 2 mg / mL tetrahydrofuran (THF) / formic acid (FA) (5%) solution with shaking for at least one hour, stored overnight at room temperature, and then filtered through a 0.45 μm polytetrafluoroethylene (PTFE) filter before GPC analysis. GPC analysis is performed under the following conditions:

[0103] Columns: One PLgel GUARD column (10 μm, 50 mm x 7.5 mm) and two hybrid B columns in series (7.5 mm x 300 mm); Column temperature: 40 °C; Mobile phase: THF / FA (5%); Flow rate: 1.0 mL / min; Injection volume: 100 mL; Detector: Agilent refractive index detector, 40 °C; and Calibration curves: PL polystyrene narrow standards with molecular weights ranging from 2,329,000 g / mol to 580 g / mol, using polynomial 3 fit.

[0104] GPC analysis of unsaturated fatty ester modified acrylic copolymer

[0105] GPC analysis is generally performed using an Agilent 1200. The sample is dissolved in dimethylformamide (DMF) / (FA) (2%) at a concentration of approximately 2 mg / mL, stored overnight at room temperature, and then filtered through a 0.45 μm PTFE filter prior to GPC analysis. GPC analysis is performed under the following conditions:

[0106] Columns: One PSS GUARD column and two PSS GRAM columns in series (8 mm x 300 mm); Column temperature: 50 °C; Mobile phase: DMF / FA (2%); Flow rate: 1.0 mL / min; Injection volume: 100 mL; Detector: Agilent refractive index detector, 50 °C; and Calibration curve: PL polyethylene glycol narrow standard, molecular weight in the range of 542500 g / mol to 1010 g / mol, using polynomial 3 fit.

[0107] Synthesis of castor oil modified acrylic copolymer dispersion A ("castor oil modified PD-A")

[0108] Sulfated castor oil (255.92 g) and DI water (1,544 g) were added to a three-necked flask reactor. DI water (57 g) and 808 g of monomer (composed of 84.6% AA / 0.3% ALMA / 15.1% MAA, by weight percentage) were added with stirring to form a monomer mixture. APS (8.11 g) was dissolved in DI water (158.84 g) to form a catalyst solution. After heating the reactor to 90 °C, the monomer mixture and catalyst solution were added to the reactor and maintained at 90 °C for 180 minutes. The reactor was then maintained at 90 °C for an additional 30 minutes. FeSO4 solution (15.9 g, 0.08%) was added to the reactor. Hydrogen peroxide solution (54.88 g, 5.7%) and IAA solution (103.6 g, 8%) were added to the reactor and maintained at 90 °C for 30 minutes. After cooling to room temperature, a NaOH solution (103 g, 3.2%) was added to the reactor, and the resulting emulsion was then filtered through a 100-mesh filter to obtain a sulfurized castor oil-modified acrylic copolymer dispersion (pH: 2.50, solids content: 33%), and the resulting aqueous resin had an M... n 26,714 g / mol).

[0109] Synthesis of polymer dispersion 1 ("PD-1 ")

[0110] DI water (2,240 g), AR-1025 surfactant (25%, 336 g), ST (2,887 g), 2-EHA (2,451 g), CHMA (1,747 g), MAA (264 g), PEM (200 g), MEUR (50%, 128 g), and AAEM (232 g) were mixed together to produce a stable monomer emulsion. Under a nitrogen atmosphere at 90 °C, AR-1025 surfactant (25%, 214 g), DI water containing ammonia (25%, 4.7 g) (20 g), monomer emulsion (463 g), and DI water containing APS (15 g) (96 g) were added to DI water (5,064 g), followed by the addition of DI water (24 g) to form a reaction mixture. Then, the remaining monomer emulsion, DI water containing APS (9g) (400g) and DI water containing ammonia (25%, 32g) (400g) were added over 120 minutes at 88°C, followed by the addition of DI water (25g). At the end of polymerization, at 60°C, a mixture of 24g of DI water containing 0.11g of FeSO4 and 24g of DI water containing 0.14g of sodium EDTA, a solution of 14.7g of tert-butyl hydroperoxide dissolved in 160g of DI water, a solution of 6.5g of IAA in 160g of DI water, a solution of 12.4g of t-BHP in 140g of DI water, and a solution of 2.3g of IAA in 80g of DI water were all added, and then at 50°C, 24g of DI water containing 100g of ammonia was added to obtain an aqueous polymer dispersion.

[0111] Synthesis of polymer dispersion 2 ("PD-2 ")

[0112] DI water (2,240 g), AR-1025 surfactant (25%, 336 g), ST (3,119 g), 2-EHA (2,451 g), CHMA (1,747 g), MAA (264 g), PEM (200 g), and MEUR (50%, 128 g) were mixed together to produce a stable monomer emulsion. At 90 °C under a nitrogen atmosphere, Fes-32 surfactant (31%, 162 g), DI water containing ammonia (25%, 4.7 g) (20 g), monomer emulsion (463 g), and DI water containing APS (15 g) (96 g) were added to DI water (5,064 g), followed by the addition of DI water (24 g) to form a reaction mixture. Then, the remaining monomer emulsion, DI water containing APS (9 g) (400 g), and DI water containing ammonia (25%, 32 g) (400 g) were added over 120 minutes at 88°C, followed by the addition of DI water (25 g). At the end of polymerization, at 60°C, a mixture of DI water containing FeSO4 (0.11 g) (24 g) and DI water containing sodium EDTA (0.14 g) (24 g), a solution of t-BHP (14.7 g) dissolved in DI water (160 g), a solution of IAA (6.5 g) in DI water (160 g), a solution of t-BHP (12.4 g) in DI water (140 g), and a solution of IAA (2.3 g) in DI water (80 g) were all added, and then DI water containing ammonia (100 g) (24 g) was added at 50°C to obtain an aqueous polymer dispersion.

[0113] Synthesis of polymer dispersion 3 ("PD-3 ")

[0114] DI water (2,240 g), AR-1025 surfactant (25%, 336 g), ST (3,760 g), 2-EHA (2,451 g), CHMA (874 g), MAA (264 g), PEM (200 g), MEUR (50%, 128 g), and AAEM (232 g) were mixed together to produce a stable monomer emulsion. Under a nitrogen atmosphere at 90 °C, AR-1025 surfactant (25%, 214 g), DI water containing ammonia (25%, 4.7 g) (20 g), monomer emulsion (463 g), and DI water containing APS (15 g) (96 g) were added to DI water (5,064 g), followed by the addition of DI water (24 g) to form a reaction mixture. Then, the remaining monomer emulsion, DI water containing APS (9 g) (400 g), and DI water containing ammonia (25%, 32 g) (400 g) were added over 120 minutes at 88°C, followed by the addition of DI water (25 g). At the end of polymerization, at 60°C, a mixture of DI water containing FeSO4 (0.11 g) (24 g) and DI water containing sodium EDTA (0.14 g) (24 g), a solution of t-BHP (14.7 g) dissolved in DI water (160 g), a solution of IAA (6.5 g) in DI water (160 g), a solution of t-BHP (12.4 g) in DI water (140 g), and a solution of IAA (2.3 g) in DI water (80 g) were all added, and then DI water containing ammonia (100 g) (24 g) was added at 50°C to obtain an aqueous polymer dispersion.

[0115] Synthesis of polymer dispersion 4 ("PD-4 ")

[0116] DI water (2,240 g), Fes-32 surfactant (31%, 271 g), ST (2,636 g), 2-EHA (2,451 g), CHMA (2,316 g), MAA (186 g), PEM (140 g), and MEUR (50%, 128 g) were mixed together to produce a stable monomer emulsion. At 90 °C under a nitrogen atmosphere, RS-610 surfactant (25%, 214 g), DI water containing ammonia (25%, 4.7 g) (20 g), monomer emulsion (463 g), and DI water containing APS (15 g) (96 g) were added to DI water (5,064 g), followed by the addition of DI water (24 g) to form a reaction mixture. Then, the remaining monomer emulsion, DI water containing APS (9 g) (400 g), and DI water containing ammonia (25%, 32 g) (400 g) were added over 120 minutes at 88°C, followed by the addition of DI water (25 g). At the end of polymerization, at 60°C, a mixture of DI water containing FeSO4 (0.11 g) (24 g) and DI water containing sodium EDTA (0.14 g) (24 g), a solution of t-BHP (14.7 g) dissolved in DI water (160 g), a solution of IAA (6.5 g) in DI water (160 g), a solution of t-BHP (12.4 g) in DI water (140 g), and a solution of IAA (2.3 g) in DI water (80 g) were all added, and then DI water containing ammonia (100 g) (24 g) was added at 50°C to obtain an aqueous polymer dispersion.

[0117] Synthesis of polymer dispersion 5 ("PD-5 ")

[0118] DI water (2,240 g), AR-1025 surfactant (25%, 336 g), ST (4,634 g), 2-EHA (2,451 g), MAA (264 g), PEM (200 g), MEUR (50%, 128 g), and AAEM (232 g) were mixed together to produce a stable monomer emulsion. Under a nitrogen atmosphere at 90 °C, AR-1025 surfactant (25%, 214 g), DI water containing ammonia (25%, 4.7 g) (20 g), monomer emulsion (463 g), and DI water containing APS (15 g) (96 g) were added to DI water (5,064 g), followed by the addition of DI water (24 g) to form a reaction mixture. Then, the remaining monomer emulsion, DI water containing APS (9 g) (400 g), and DI water containing ammonia (25%, 32 g) (400 g) were added over 120 minutes at 88°C, followed by the addition of DI water (25 g). At the end of polymerization, at 60°C, a mixture of DI water containing FeSO4 (0.11 g) (24 g) and DI water containing sodium EDTA (0.14 g) (24 g), a solution of t-BHP (14.7 g) dissolved in DI water (160 g), a solution of IAA (6.5 g) in DI water (160 g), a solution of t-BHP (12.4 g) in DI water (140 g), and a solution of IAA (2.3 g) in DI water (80 g) were all added, and then DI water containing ammonia (100 g) (24 g) was added at 50°C to obtain an aqueous polymer dispersion.

[0119] The properties of the obtained aqueous dispersions of PD-1 to PD-5 are given in Table 1.

[0120] Table 1 : Properties of waterborne polymer dispersions

[0121] Polymer dispersion pH Solids content, % Particle size, nm PD-1 7.5 41.50 90 PD-2 7.66 42.50 81 PD-3 9.51 41.81 84 PD-5 8.85 42.50 84 PD-4 7.79 42.47 81

[0122] *The solids content was measured according to the test method described above.

[0123] Example (Ex) 1 - Example 2 and Example 4 - Example 6 and Comparative (Comp) Example 2 - Comparative Example 4, Comparative Example 7 - Comparative Example 8 and Comparative Example 10 waterborne polymer compositions

[0124] N,N-Dimethylethanolamine (DMEA) (0.72 g) was added to YG-EA670 epoxy ester resin (measured solids content: 75%, 12 g) under stirring. After stirring for 5 minutes, water (12 g) was further added to the resulting mixture under stirring. After the water feed was complete, the mixture was stirred for 15 minutes at 1,000 rpm using a high-speed disperser to form a solution of the aqueous epoxy ester resin. Then, based on the formulation given in Table 2, the aqueous polymer dispersion prepared above was added to the solution of the aqueous epoxy ester resin under stirring to form an aqueous polymer composition (i.e., a mixture of emulsion polymer and aqueous epoxy ester).

[0125] Example 3

[0126] RETAN 540 (2.72 g) was added to PD-1 (100 g) and mixed evenly to obtain the mixture of Example 3.

[0127] Comparative Example 5

[0128] Castor oil-modified PD-A (3.22 g) was added to PD-1 (100 g) and mixed evenly to obtain the mixture of Comparative Example 5.

[0129] Comparative Example 6

[0130] DMEA (1.58 g), oleic acid (5 g), and water (25 g) were mixed with stirring. The resulting mixture was added to PD-1 (68.42 g) to obtain Comparative Example 6.

[0131] Comparative Example 9

[0132] RETAN 540 (9.23 g) was added to PD-1 (100 g) and then mixed evenly to obtain the mixture of Comparative Example 9.

[0133] Table 2: Waterborne polymer compositions

[0134]

[0135] 1 Except for Comparative Example 6, the percentages refer to the dry weight of the aqueous resin relative to the total dry weight of the aqueous resin and the polymer dispersion, where

[0136] Dry weight (waterborne resin) = weight (waterborne resin) × solids content (waterborne resin); and

[0137] Dry weight (polymer dispersion) = weight (polymer dispersion) × solids content (polymer dispersion). The percentages in Comparative Example 6 refer to the weight of oleic acid relative to the total weight of oleic acid and the dry weight of the polymer dispersion.

[0138] 2 The solids content of an aqueous polymer composition is calculated based on the concentration and solids content of the aqueous resin and polymer dispersion in the aqueous polymer composition.

[0139] Coating formulation

[0140] Based on the formulations given in Tables 3 and 4, the aqueous polymer compositions of Examples 1-6 and Comparative Examples 1-10 obtained above were used as binders for the preparation of coating formulations 1-6 and comparative coatings 1-10, respectively. The components in abrasive particles-1 and abrasive particles-2 were prepared using a high-speed disperser (mixing speed: 800 rpm-3,000 rpm) to form abrasive particles-1 and abrasive particles-2, respectively. The obtained abrasive particles were mixed with the binder using a conventional laboratory mixer (mixing speed: 50 rpm-1,000 rpm), and subsequently mixed with other components in the letdown stage. Table 4 lists the specific binder compositions for each coating formulation and the loading amounts of binder, Texanol, and water used in the letdown stage. The properties of the obtained coating formulations were evaluated according to the test methods described above, and the results are given in Table 4.

[0141] As shown in Table 4, after 130 hours of salt spray resistance (SSR) testing, all coatings including the binders of Examples 1-6 exhibited good corrosion resistance, as indicated by creep along the scratch not exceeding 2 mm. The binders of Examples 1-5 also provided coatings with good early water resistance at grade 10. Conversely, the coating including PD-1 as the sole binder (Comparative Example 1) failed to meet the creep requirement (i.e., ≤2 mm). Binders containing AAEM-free structural units (Comparative Example 3), CHMA-free structural units (Comparative Example 4), or containing 30% CHMA (Comparative Example 10) all provided coatings with poor corrosion resistance, as indicated by creep along scratches much wider than 2 mm. The binder of Comparative Example 5, including castor oil-modified PD-A, failed to provide a coating with corrosion resistance meeting the creep requirement. The binder of Comparative Example 6, including 5% oleic acid, failed to provide a coating with the desired corrosion resistance. The binders, including 15% dry weight, 8% dry weight, or 0.5% dry weight YG-EA670 (Comparative Examples 2, 7, and 8) or 8% dry weight RETAN 540 (Comparative Example 9), all provided coatings with a creep width greater than 2 mm at the scribing point after the SSR test. Compared to the binder of Example 1, the binder of Comparative Example 2 provided coatings with poor early water resistance.

[0142] Table 3. Coating formulation

[0143]

[0144]

[0145] Table 4: Coating formulation (binder, Texanol and water) and properties

[0146]

Claims

1. An aqueous polymer composition, said aqueous polymer composition comprising: (A) An emulsion polymer, wherein, based on the weight of the emulsion polymer, the emulsion polymer comprises: 5% to 28% by weight of cycloalkyl (meth)acrylate structural units, Structural units of 0.1 wt% to 10 wt% of acetylacetoxy or acetylacetamide functional monomers. 0.05% to 10% by weight of phosphorous acid monomers, their salts, or mixtures thereof as structural units. Zero to 10% by weight of additional olefinic unsaturated acid monomers, and Other structural units of olefinically unsaturated nonionic monomers; and (B) 0.7% to 7.8% of a waterborne resin, based on the total dry weight of the emulsion polymer and the waterborne resin, wherein the waterborne resin comprises at least one fatty acid ester segment and has a number average molecular weight of 20,000 g / mol or less.

2. The aqueous polymer composition according to claim 1, wherein the aqueous resin is selected from the group consisting of: aqueous epoxy esters, unsaturated fatty acid ester modified acrylic copolymers, or mixtures thereof.

3. The aqueous polymer composition according to claim 2, wherein, based on the weight of the unsaturated fatty acid ester modified acrylic copolymer, the unsaturated fatty acid ester modified acrylic copolymer comprises 20% by weight or more of (meth)acrylic acid structural units.

4. The aqueous polymer composition according to claim 2, wherein the unsaturated fatty acid ester modified acrylic copolymer is a castor oil or sulfated castor oil modified acrylic copolymer.

5. The aqueous polymer composition according to claim 2, wherein the aqueous epoxy ester comprises the reaction product of unsaturated fatty acids and optionally other compounds containing carboxylic acid groups with the epoxy compound.

6. The aqueous polymer composition according to claim 5, wherein the aqueous epoxy ester is a (meth)acrylic acid-functionalized aqueous epoxy ester.

7. The aqueous polymer composition according to any one of claims 1 to 6, wherein the acetoacetoxy or acetoacetamide functional monomer is selected from the group consisting of: acetoacetoxyethyl methacrylate, acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, allyl acetoacetate, acetoacetoxybutyl methacrylate, 2,3-di(acetoacetoxy)propyl methacrylate, or mixtures thereof.

8. The aqueous polymer composition according to any one of claims 1 to 6, wherein the (meth)acrylate cycloalkyl ester is selected from the group consisting of: cyclohexyl methacrylate, cyclohexyl acrylate, methylcyclohexyl acrylate, or mixtures thereof.

9. The aqueous polymer composition according to any one of claims 1 to 6, wherein the phosphorous monomer is selected from the group consisting of ethyl methacrylate, ethyl acrylate, allyl ether phosphate, or mixtures thereof.

10. The aqueous polymer composition according to any one of claims 1 to 6, wherein, based on the weight of the emulsion polymer, the emulsion polymer comprises: 10% to 25% by weight of the structural units of the (meth)acrylate cycloalkyl ester; 1.5% to 4% by weight of the structural unit of the acetylacetoxy or acetylacetamide functional monomer; 1.5% to 4% by weight of the structural unit of the phosphorous monomer, its salt or mixture thereof; and the structural unit of the additional olefinic unsaturated nonionic monomer; and optionally, 0% to 3% by weight of the structural unit of the olefinic unsaturated functional monomer having one or more functional groups selected from the group consisting of ureido, amide, amino, silane, hydroxyl or combinations thereof.

11. The aqueous polymer composition according to any one of claims 1 to 6, wherein the aqueous polymer composition comprises from 1% to 7.5% of the aqueous resin based on the total dry weight of the emulsion polymer and the aqueous resin.

12. The aqueous polymer composition according to any one of claims 1 to 6, wherein the emulsion polymer further comprises structural units capable of polymerizing surfactants.

13. A method for preparing an aqueous polymer composition according to any one of claims 1 to 12 by mixing the emulsion polymer with the aqueous resin.

14. A coating composition comprising an aqueous polymer composition according to any one of claims 1 to 12 and optionally a pigment.

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