Copolymer Additive

Abstract

The present invention provides a copolymer additive comprising water and a copolymer prepared from an acetoacetamide-functional monomer and a ureido monomer, the copolymer additive being stable over a wide pH range, and provides a coating composition comprising such a copolymer additive, the coating composition being capable of providing good formaldehyde emission reduction performance and good yellowing resistance for a coating film made therefrom.

Description

Technical Field

[0001] The present invention relates to a copolymer additive and a coating composition comprising the copolymer additive. Background Art

[0002] Aqueous compositions (also known as water-based compositions) are becoming increasingly important compared to solvent-based compositions due to fewer environmental problems. Environmental regulations regarding reducing health risks due to indoor exposure to air pollutants such as formaldehyde are becoming increasingly stringent. For example, the Chinese indoor air purification standard JC / T 1074-2008 requires that the formaldehyde emission reduction efficiency of interior building coatings be at least 75%. Attempts have been made to reduce free formaldehyde released from the indoor environment. For example, water-based polymers containing acetoacetoxy groups have been developed as formaldehyde emission reduction materials for coating applications. However, the acetoacetoxy groups in the polymer tend to hydrolyze in water during storage, which can lead to pressure buildup in the container, thus creating safety problems. One effective way to avoid severe hydrolysis is to protect the acetoacetoxy groups by using some selective organic amines (such as ethanolamine), but the coating films containing acetoacetoxy-functional polymers and amines tend to show discoloration (e.g., yellowing) over time when exposed to sunlight, especially when the coating films age.

[0003] There is a desire to find an additive suitable for coating compositions without the above problems. Summary of the Invention

[0004] The present invention solves the problem of finding a copolymer additive without the above problems. The copolymer additive of the present invention comprises a copolymer prepared by polymerization of a novel combination of acetoacetamide-functional monomers and ureido monomers. Compared with similar copolymer additives having structural units containing acetoacetoxy-functional monomers instead of acetoacetamide-functional monomers, the copolymer additive of the present invention is more stable within a wide pH range (e.g., 2 to 10). A coating composition comprising the copolymer additive of the present invention can provide less yellowing for the coating film prepared therefrom compared to a similar coating composition containing an acetoacetoxy-functional binder. These properties can be measured according to the test methods described in the Examples section below.

[0005] In a first aspect, the present invention is a copolymer additive, the copolymer additive comprising a copolymer having a weight average molecular weight of 1,000 grams per mole (g / mol) to 10,000 g / mol and water,

[0006] wherein, based on the weight of the copolymer by weight, the copolymer comprises:

[0007] 4% to 60% of structural units of acetoacetamide-functional monomers having the structure of formula (I):

[0008]

[0009] wherein R 1 is selected from the following structures:

[0010]

[0011] wherein R 2 , R 4 , R 8 , R 10 , R 12 and R 13 are each independently an alkylene group having 2 to 20 carbon atoms, R 3 , R 5 , R 6 , R 7 and R 11 are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, R 9 is hydrogen or an alkyl group having 1 to 20 carbon atoms

[0012] groups, and X is –O– or –N–; and

[0013] structural units of 40% to 96% of the ureido monomer.

[0014] In a second aspect, the present invention is a coating composition, the coating composition comprising:

[0015] a binder having a weight average molecular weight of 100,000 g / mol or greater, and

[0016] based on the total weight of the coating composition, 0.08% to 3% by dry weight of the copolymer additive of the first aspect. Detailed Description

[0017] As used herein, an “aqueous” composition or dispersion means particles dispersed in an aqueous medium. The “aqueous medium” herein refers to water and 0 wt% to 30 wt% of a water-miscible compound based on the weight of the medium, such as an alcohol, a diol, a diol ether, a diol ester, or a mixture thereof.

[0018] Throughout the document, the word fragment “(meth)acryloyl” refers to both “methacryloyl” and “acryloyl”. For example, (meth)acrylic acid refers to both methacrylic acid and acrylic acid, and (meth)methyl acrylate refers to both methyl methacrylate and methyl acrylate.

[0019] As used herein, “glass transition temperature” or “T g ” can be measured by various techniques, including, for example, differential scanning calorimetry (“DSC”) or calculations using the Fox equation. The T reported hereing The specific value is the value calculated using the Fox equation (T.G. Fox, Bull. Am. Physics Soc., Vol. 1, No. 3, p. 123 (1956)). For example, for calculating the copolymer of monomers M 1 and M 2 the T g ,

[0020]

[0021] where T g (calculated) is the glass transition temperature calculated for the copolymer, w(M 1 ) is the weight fraction of monomer M 1 in the copolymer, w(M 2 ) is the weight fraction of monomer M 2 in the copolymer, T g (M 1 ) is the glass transition temperature of the homopolymer of monomer M 1 , and T g (M 2 ) is the glass transition temperature of the homopolymer of monomer M 2 ; all temperatures are in K. The glass transition temperatures of the homopolymers can be found, for example, in "Polymer Handbook" edited by J. Brandrup and E.H. Immergut, Interscience Publishers.

[0022] The "structural unit" (also referred to as "polymerization unit") that names a monomer refers to the residue of the monomer after polymerization, i.e., the polymerized monomer or the monomer in polymerized form. For example, the structural unit of methyl methacrylate is shown below:

[0023]

[0024] where the dashed line indicates the attachment point of the structural unit to the polymer backbone.

[0025] The copolymer additive of the present invention comprises the structural units of one or more acetoacetamide functional monomers. An acetoacetamide functional monomer refers to a monomer containing at least one acetoacetyl amino group. The acetoacetamide functional monomer that can be used in the present invention has the structure of formula (I):

[0026]

[0027] where R 1 is selected from the following structures:

[0028]

[0029] wherein R 2 , R 4 , R 8 , R 10 , R 12 and R 13 are each independently an alkylene group having 2 to 20 carbon atoms, 3 to 12 carbon atoms or 4 to 8 carbon atoms, such as an ethylene group (–CH 2 CH 2 –) and a propylene group (–CH 2 CH 2 CH 2 –); R 3 , R 5 , R 6 , R 7 and R 11 are each independently hydrogen (H) or an alkyl group having 1 to 8 carbon atoms or 2 to 4 carbon atoms, such as methyl and ethyl; R 9 is H or an alkyl group having 1 to 20 carbon atoms, 3 to 12 carbon atoms or 4 to 8 carbon atoms; and X is –O– or –N–. Preferably, R 1 has the structure of (II-a), wherein X is –O–, R 2 is –CH 2 CH 2 –, and R 3 is –CH 3 . "Alkyl" refers to a monovalent saturated hydrocarbon group, such as methyl. "Alkylene" refers to a divalent saturated aliphatic radical, such as –CH 2 CH 2 –.

[0030] The acetoacetamide functional monomer may be an acetoacetamidoalkyl (meth)acrylate. Examples of suitable acetoacetamide functional monomers include acetoacetamidoethyl methacrylate (N-AAEM), acetoacetamidoethyl acrylate, acetoacetamidoethyl (meth)acrylamide, acetoacetamidoethyl maleate, acetoacetamidoethyl itaconate, or mixtures thereof. Preferably, the acetoacetamide functional monomer is acetoacetamidoethyl methacrylate.

[0031] The acetoacetamide-functional monomer useful in the present invention can be synthesized by reacting N-(2-hydroxyethyl)acetoacetamide with the following ethylenically unsaturated ionic monomer (e.g., carboxylic acid monomer), an alkyl ester of (meth)acrylic acid or a mixture thereof through an esterification or transesterification reaction. The alkyl ester of (meth)acrylic acid useful in the present invention can be a C1-C20-, C1-C10- or C1-C8 alkyl ester of (meth)acrylic acid, including, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate or a mixture thereof. Preferably, the ethylenically unsaturated ionic monomer is an acid anhydride of the following carboxylic acid monomer. More preferably, (meth)acrylic anhydride is used to react with N-(2-hydroxyethyl)acetoacetamide.

[0032] Based on the weight of the copolymer, the copolymer in the copolymer additive of the present invention may contain the structural units of the acetoacetamide-functional monomer in the following amounts: 4% or more, 5% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 13% or more, 14% or more or even 15% or more, while 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 32% or less, 30% or less, 28% or less, 25% or less, 22% or less or even 20% or less.

[0033] The copolymer in the copolymer additive of the present invention contains the structural units of one or more ureido monomers. As used herein, the term "ureido monomer" refers to an ethylenically unsaturated compound containing one or more cyclic ureido groups (i.e., imidazolin-2-one groups). The ureido monomer may contain a (meth)acrylate group, a vinyl group or a (meth)acrylamido group. Suitable ureido monomers may include, for example

[0034]

[0035] or a mixture thereof.

[0036] Based on the weight of the copolymer, the copolymer in the copolymer additive of the present invention may comprise the structural units of the ureido monomer in the following amounts: 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 68% or more, 70% or more, 72% or more, 75% or more or even 78% or more, while 96% or less, 95% or less, 93% or less, 92% or less, 91% or less, 90% or less, 89% or less, 88% or less, 87% or less, 86% or less or even 85% or less.

[0037] The copolymer in the copolymer additive of the present invention may optionally comprise one or more ethylenically unsaturated ionic monomers. The term "ionic monomer" herein refers to a monomer having an ionic charge between pH = 1 - 14. The ethylenically unsaturated ionic monomers may include carboxylic acid monomers, phosphoric acid-containing monomers, sulfonic acid monomers, sulfate monomers; their salts; or mixtures thereof. The carboxylic acid monomers may be α,β-ethylenically unsaturated carboxylic acids, monomers with acid-forming groups that generate or are subsequently converted to such acid groups (such as acid anhydrides, (meth)acrylic anhydride or maleic anhydride); or mixtures thereof. Specific examples of the carboxylic acid monomers include acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, fumaric acid or mixtures thereof. The sulfonic acid monomers and their salts may include sodium vinyl sulfonate (SVS), sodium styrene sulfonate (SSS), acrylamido-methyl-propane sulfonate (AMPS) or mixtures thereof, one or more phosphoric acid-containing monomers, their salts or mixtures thereof. Suitable phosphorus-containing acid monomers and their salts may include (meth)acrylic acid phosphoroalkyl esters, such as (meth)acrylic acid phosphoethyl ester, (meth)acrylic acid phosphopropyl ester, (meth)acrylic acid phosphobutyl ester, their salts and mixtures thereof; CH 2 =C(R 1 )-C(O)-O-(R 2 O) q -P(O)(OH) 2 where R 1 =H or CH 3 , R 2= an alkylene group, such as an ethylene group, a propylene group, a butylene group or a combination thereof; and q = 1-20, such as SIPOMER PAM-100, SIPOMER PAM-200, SIPOMER PAM-300, SIPOMER PAM-600 and SIPOMER PAM-4000, all of which are available from Solvay; (meth)acrylic phosphanyloxy esters, such as phosphoethylene glycol (meth)acrylate, phosphodiethylene glycol (meth)acrylate, phosphotriethylene glycol (meth)acrylate, phosphopropylene glycol (meth)acrylate, phosphodipropylene glycol (meth)acrylate, phosphotripropylene glycol (meth)acrylate, their salts and their mixtures. A preferred phosphorus-containing acid monomer is ethyl phosphate methacrylate (PEM). Based on the weight of the copolymer, the copolymer in the copolymer additive may contain the following amounts of structural units of ethylenically unsaturated ionic monomers: 0 or more, 0.05% or more, 0.1% or more, 1% or more, 2% or more or even 3% or more, while 35% or less, 30% or less, 25% or less, 20% or less, 18% or less, 15% or less, 10% or less or even 5% or less.

[0038] The copolymer in the copolymer additive of the present invention may optionally contain structural units of one or more ethylenically unsaturated nonionic monomers different from the acetoacetamide functional monomer and the ureido monomer. The term "nonionic monomer" herein refers to a monomer that does not carry an ionic charge between pH = 1-14. The nonionic monomer may be selected from the group consisting of: hydroxy-functional (meth)acrylic acid alkyl esters; (meth)acrylamide; diacetone (meth)acrylamide; vinyltrialkoxysilane, (meth)acryloyl-functional silane; glycidyl (meth)acrylate, or a combination thereof. Suitable hydroxy-functional (meth)acrylic acid alkyl esters include, for example, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, or a mixture thereof. Examples of suitable vinyltrialkoxysilanes include vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane, vinyldimethylethoxysilane, and vinylmethyldiethoxysilane, or a mixture thereof. Examples of suitable (meth)acryloyl-functional silanes include (meth)acryloyloxyalkyltrialkoxysilanes, such as γ-methacryloyloxypropyltrimethoxysilane and methacryloyloxypropyltriethoxysilane; 3-methacryloyloxypropylmethyldimethoxysilane; 3-methacryloyloxypropyltrimethoxysilane; 3-methacryloyloxypropyltriethoxysilane; or a mixture thereof. Based on the weight of the copolymer by weight, the copolymer may contain 0 or more, 0.05% or more, 0.1% or more, 1% or more, or even 3% or more, while 18% or less, 15% or more, 10% or less, or even 5% or less of the structural units of the ethylenically unsaturated nonionic monomer. The total weight concentration of the structural units of the above monomers may be 100%.

[0039] Preferably, based on the weight of the copolymer by weight, the copolymer in the copolymer additive contains 4% to 60% of the structural units of the acetoacetamide functional monomer and 40% to 96% of the structural units of the ureido monomer, more preferably, 8% to 25% of the structural units of the acetoacetamide functional monomer and 75% to 92% of the structural units of the ureido monomer; and 0 to 18% of the structural units of the ethylenically unsaturated ionic monomer; and 0 to 18% of the structural units of the ethylenically unsaturated nonionic monomer. More preferably, the total weight concentration of the structural units of the acetoacetamide functional monomer and the ureido monomer is 100%.

[0040] The copolymer in the copolymer additive of the present invention may have a weight-average molecular weight (Mw) in the following ranges: 1,000 grams per mole (g / mol) or greater, 1,200 g / mol or greater, 1,500 g / mol or greater, 1,800 g / mol or greater, 2,000 g / mol or greater, 2,200 g / mol or greater, 2,500 g / mol or greater, 2,800 g / mol or greater, 3,000 g / mol or greater or even 3,200 g / mol or greater, while 10,000 g / mol or less, 9,800 g / mol or less, 9,500 g / mol or less, 9,200 g / mol or less, 9,000 g / mol or less, 8,800 g / mol or less, 8,500 g / mol or less, 8,200 g / mol or less, 8,000 g / mol or less, 7,800 g / mol or less, 7,500 g / mol or less, 7,200 g / mol or less, 7,000 g / mol or less, 6,800 g / mol or less, 6,500 g / mol or less, 6,200 g / mol or less, 6,000 g / mol or less or even 5,900 g / mol or less. M n It can be determined by gel permeation chromatography (GPC) analysis as described in the Examples section below.

[0041] The copolymer additive of the present invention can be prepared by solution polymerization of the above monomers. The total weight concentration of the monomers used to prepare the copolymer is equal to 100%. The monomers can be added individually or as an aqueous solution; or added once or multiple times or continuously, linearly or non-linearly during the reaction period for preparing the copolymer additive. The temperature suitable for the polymerization process can be lower than 100 degrees Celsius (°C), in the range of 30°C to 95°C, or in the range of 50°C to 90°C.

[0042] The copolymer additive of the present invention further contains water. The water is present in an amount to provide a desired solid content (e.g., 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more or even 30% by weight or more based on the weight of the copolymer additive, while 60% by weight or less, 55% by weight or less or even 50% by weight or less). The solid content can be measured according to the test method described in the Examples section below.

[0043] In the polymerization process for preparing the copolymer additive, free radical initiators and / or chain transfer agents can be used. The polymerization process can be thermal-initiated or redox-initiated free radical polymerization. Examples of suitable free radical initiators include hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium and / or alkali metal persulfates, sodium perborate, perphosphoric acid and their salts; potassium permanganate and ammonium or alkali metal salts of peroxydisulfuric acid. Based on the total weight of the monomers, the free radical initiator can generally be used in an amount of 0.01% to 3.0% by weight. In the polymerization method, a redox system containing the above initiator and a suitable reducing agent can be used. Examples of suitable reducing agents include sodium formaldehyde sulfoxylate, ascorbic acid, isoascorbic acid, alkali metal salts and ammonium salts of sulfur-containing acids (such as sodium sulfite, bisulfite, thiosulfate, hyposulfite, sulfide, hydrosulfide or dithionite), acetone bisulfite, glycolic acid, hydroxymethanesulfonic 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. A metal chelating agent can be optionally used. Examples of suitable chain transfer agents include 3-mercaptopropionic acid, n-dodecyl mercaptan, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, benzenethiol, alkyl mercaptans of azelaic acid, sodium hypophosphite, sodium bisulfite, sodium metabisulfite, phosphorous acid, isopropyl alcohol, sodium formate or mixtures thereof. Based on the total weight of the monomers used to prepare the copolymer by weight, the chain transfer agent can be used in an effective amount to control the molecular weight of the copolymer (e.g., 0 to 15%, 0.1% to 12%, 0.15% to 10% or 0.2% to 8%).

[0044] After completion of the polymerization, the obtained copolymer additive can be neutralized to a pH value of, for example, 2 or higher, 3 or higher, 4 or higher, 5 or higher, 6 or higher or even 7 or higher while 10 or lower, 9.5 or lower, 9 or lower or even 8.5 or lower. Examples of suitable neutralizing agents include ammonia, 2-amino-2-methyl-1-propanol (AMP-95), ethanolamine (MEA), diethanolamine, 2-dimethylaminoethanol, sodium hydroxide (NaOH), potassium hydroxide (KOH), Jeffamine D-230 polyetheramine available from Huntsman or mixtures thereof. The obtained copolymer is generally soluble in water at a temperature in the range of 15°C to 30°C.

[0045] Compared with similar copolymer additives having structural units of acetoacetoxy-functional monomers (e.g., ethyl acetoacetoxy (meth)acrylate) rather than acetoacetamide-functional monomers, the copolymer additives of the present invention are more stable (i.e., show less hydrolysis) within the above-mentioned wide pH range (e.g., 2 to 10). For example, according to the test method described in the following Examples section, after thermal aging at 80 °C for 1 day, based on the weight of the copolymer additive by weight, the copolymer additives of the present invention show a Δ acetone level of less than 400 parts per million (ppm), less than 380 ppm, less than 350 ppm, less than 320 ppm, less than 300 ppm, less than 200 ppm, or even less than 100 ppm.

[0046] The present invention also relates to a coating composition comprising a copolymer additive and one or more binders. Based on the total weight of the coating composition on a dry weight basis, the copolymer additive can be present in the coating composition in the following amounts: 0.08% or more, 0.09% or more, 0.1% or more, 0.12% or more, 0.14% or more, 0.15% or more, 0.18% or more, or even 0.2% or more, while 3% or less, 2.8% or less, 2.5% or less, 2.2% or less, 2% or less, 1.8% or less, 1.5% or less, 1.2% or less, 1% or less, or even 0.8% or less. Preferably, based on the total weight of the coating composition by weight, the coating composition comprises the following amounts of structural units of acetoacetamide-functional monomers: 0.04% or more, 0.05% or more, 0.06% or more, 0.07% or more, or even 0.08% or more, while 0.4% or less, 0.38% or less, 0.35% or less, 0.32% or less, 0.3% or less, 0.28% or less, 0.25% or less, 0.22% or less, 0.2% or less, 0.18% or less, 0.15% or less, 0.14% or less, 0.12% or less, or even 0.11% or less.

[0047] The coating composition of the present invention further comprises one or more binders that are typically supplied in the form of an aqueous dispersion. The binder (also referred to as a film-forming polymer) can be an emulsion polymer. The binder can comprise an acrylic polymer. As used herein, "acrylic polymer" refers to a homopolymer of acrylic monomers or a copolymer of acrylic monomers with different acrylic monomers or other monomers (such as styrene, substituted styrene, and vinyl acetate). The acrylic polymer can be an acrylic homopolymer, a styrene-acrylic copolymer, a vinyl acetate-acrylic copolymer, or a mixture thereof. As used herein, "acrylic monomer" includes (meth)acrylic acid, (meth)acrylic alkyl esters, (meth)acrylamide, (meth)acrylonitrile, and modified forms thereof, such as (meth)acrylic hydroxyalkyl esters.

[0048] The binder in the coating composition of the present invention may comprise structural units of one or more ethylenically unsaturated ionic monomers and structural units of one or more ethylenically unsaturated nonionic monomers. Suitable ethylenically unsaturated ionic monomers herein may include those described in the copolymer additive portion above, such as (meth)acrylic acid. Based on the weight of the binder, the binder may comprise 0.1% to 15% by weight (e.g., 0.1% to 10%, 0.5% to 8%, 1% to 6%, 1.5% to 5% or 2% to 4%) of structural units of ethylenically unsaturated ionic monomers. Suitable ethylenically unsaturated nonionic monomers herein include those nonionic monomers described in the copolymer additive portion above, such as methyl (meth)acrylate, butyl (meth)acrylate, styrene, vinyl acetate, ethyl acrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate or mixtures thereof. Based on the dry weight of the binder, the binder may comprise 85% to 99.9%, 90% to 99.9%, 92% to 99.5%, 93% to 99%, 95% to 98.5% or 96% to 98% by weight of structural units of monoethylenically unsaturated nonionic monomers. The binder may optionally comprise structural units of one or more polyethylenically unsaturated nonionic monomers (including difunctional, trifunctional, tetrafunctional or higher polyfunctional ethylenically unsaturated monomers). Examples of suitable polyethylenically unsaturated monomers include butadiene, allyl (meth)acrylate, divinylbenzene, ethylene glycol dimethacrylate, butanediol dimethacrylate or mixtures thereof. Based on the dry weight of the binder, the binder may comprise 0 to 5%, 0.1% to 3% or 0.5% to 1.5% by weight of structural units of polyethylenically unsaturated nonionic monomers. The binder in the coating composition may or may not (i.e., be free of) comprise structural units of acetoacetoxy-functional monomers (such as ethyl acetoacetoxy methacrylate), for example, based on the dry weight of the binder, the binder may comprise the following amounts of structural units of acetoacetoxy-functional monomers: less than 1.5%, less than 1.2%, less than 1%, less than 0.8%, less than 0.5%, less than 0.1% or even 0.

[0049] The binder in the coating composition of the present invention may have a T of -15°C to 50°C, -10°C to 30°C or -5°C to 10°C g, as calculated by the above Fox formula. The binder useful in the present invention may have a weight average molecular weight (Mw) of 100,000 g / mol or greater, 110,000 g / mol or greater, 120,000 g / mol or greater, 140,000 g / mol or greater, 150,000 g / mol or greater, 160,000 g / mol or greater, 180,000 g / mol or greater, 200,000 g / mol or greater, 300,000 g / mol or greater, 400,000 g / mol or greater, 500,000 g / mol or greater, 600,000 g / mol or greater, 700,000 g / mol or greater, 800,000 g / mol or greater, 1,000,000 g / mol or greater or even 1,200,000 g / mol or greater. M n It can be determined by GPC analysis as described in the Examples section below.

[0050] The binder in the coating composition of the present invention may have a minimum film forming temperature (MFFT) in the range of -10 °C to 70 °C, 10 °C to 60 °C or 20 °C to 55 °C, as determined according to ASTM D 2354-10 (2018). The binder particles in the coating composition of the present invention may have a particle size of 50 nanometers (nm) to 500 nm, 80 nm to 200 nm or 90 nm to 150 nm. The particle size herein refers to the Z-average size and can be measured by a Brookhaven BI-90Plus particle size analyzer.

[0051] The coating composition of the present invention may comprise one or more pigments. As used herein, "pigment" refers to particulate inorganic materials that can substantially contribute to the opacity or hiding power of the coating. The refractive index of such materials is generally greater than 1.8. Inorganic pigments may include, for example, titanium dioxide (TiO 2 ), zinc oxide, iron oxide, zinc sulfide, barium sulfate, barium carbonate or mixtures thereof. In a preferred embodiment, the pigment used in the present invention is TiO 2 . TiO 2 generally exists in two crystal forms, namely anatase and rutile. TiO 2 can also be obtained in the form of a concentrated dispersion.

[0052] The coating composition of the present invention may comprise one or more extenders. As used herein, the term "extender" refers to particulate inorganic materials having a refractive index less than or equal to 1.8 and greater than 1.3. Examples of suitable extenders include calcium carbonate, clay, calcium sulfate, aluminum silicate, silicate, zeolite, mica, diatomaceous earth, solid or hollow glass, ceramic beads, nepheline syenite, feldspar, diatomite, calcined diatomite, talc (hydrated magnesium silicate), silica, alumina, kaolin, pyrophyllite, perlite, barite, wollastonite, opaque polymers (such as ROPAQUE TM Ultra E (ROPAQUE is a trademark of The Dow Chemical Company)) or mixtures thereof. The coating composition may have a pigment volume concentration (PVC) of 15% or greater, 20% or greater, 25% or greater, 30% or greater or even 35% or greater while 90% or less, 88% or less, 85% or less, 70% or less or even 60% or less. The PVC can be determined by the following formula:

[0053] PVC = [volume (颜料+增量剂) / dry volume (颜料+增量剂+粘结剂) × 100%.

[0054] The coating composition of the present invention may comprise one or more defoamers. As used herein, the term "defoamer" refers to chemical additives that reduce and impede the formation of foam. The defoamer can be a silicone-based defoamer, a mineral oil-based defoamer, an ethylene oxide / propylene oxide-based defoamer, an alkyl polyacrylate or a mixture thereof. Suitable commercially available defoamers include, for example, TEGO Airex 902W and TEGO Foamex 1488 polyether silicone copolymer emulsions, both available from TEGO, BYK-024 silicone defoamer available from BYK or mixtures thereof. Based on the total weight of the coating composition by weight, the defoamer may be present in an amount of 0 to 1%, 0.05% to 0.8% or 0.1% to 0.5%.

[0055] The coating composition of the present invention may comprise one or more thickeners. The thickeners may include polyvinyl alcohol (PVA), clay materials, acid derivatives, acid copolymers, urethane associative thickeners (UAT), polyether urea polyurethanes (PEUPU), polyether polyurethanes (PEPU), or mixtures thereof. Examples of suitable thickeners include alkali-swellable emulsions (ASE), such as sodium- or ammonium-neutralized acrylic polymers; hydrophobically modified alkali-swellable emulsions (HASE), such as hydrophobically modified acrylic copolymers; associative thickeners, such as hydrophobically modified ethoxylated urethanes (HEUR); and 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 methyl cellulose, 2-hydroxyethyl methyl cellulose, 2-hydroxybutyl methyl cellulose, 2-hydroxyethyl ethyl cellulose, and 2-hydroxypropyl cellulose. Preferably, the thickener is hydrophobically modified hydroxyethyl cellulose (HMHEC). Based on the total weight of the coating composition by weight, the thickener may be present in an amount of 0 to 5%, 0.1% to 3%, or 0.2% to 1%.

[0056] The coating composition of the present invention may also comprise one or more wetting agents. The term "wetting agent" herein refers to a chemical additive that reduces the surface tension of the coating composition, thereby making it easier for the coating composition to spread on the surface of the substrate or penetrate the surface of the substrate. The wetting agent may be anionic, zwitterionic, or nonionic polycarboxylate esters. Based on the total weight of the coating composition by weight, the wetting agent may be present in an amount of 0 to 2.5%, 0.5% to 2%, or 1% to 1.5%.

[0057] The coating composition of the present invention may comprise one or more dispersants. The dispersants may include nonionic, anionic, or cationic dispersants, such as polybasic acids having a suitable molecular weight, 2-amino-2-methyl-1-propanol (AMP), dimethylaminoethanol (DMAE), potassium tripolyphosphate (KTPP), trisodium polyphosphate (TSPP), citric acid, and other carboxylic acids. The polybasic acids used may include homopolymers and copolymers based on polycarboxylic acids (e.g., having a weight average molecular weight in the range of 1,000 to less than 50,000, as measured by GPC), including those that have been hydrophobically or hydrophilically modified, such as polyacrylic acid or polymethacrylic acid or maleic anhydride, as well as various monomers (such as styrene, acrylate or methacrylate, diisobutene, and other hydrophilic or hydrophobic comonomers); their salts; or mixtures thereof. Based on the total weight of the coating composition by weight, the dispersant may be present in an amount of 0 to 5%, 0.2% to 3%, or 0.3% to 2%.

[0058] The coating composition of the present invention may comprise one or more coalescing agents. The term "coalescing agent" herein refers to a slow-evaporating solvent that causes polymer particles to fuse 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 by weight, the coalescing agent may be present in an amount of 0 or more, 0.1% or more, 1% or more, or even 3% or more, while 10% or less, 9% or less, or even 8% or less.

[0059] In addition to the above components, the coating composition of the present invention may further comprise any one or a combination of the following additives: buffering agents, neutralizing agents, photocrosslinking agents, antifreezing agents, humectants, mildew-proof agents, biocides, anti-skinning agents, colorants, flow agents, antioxidants, plasticizers, leveling agents, thixotropic agents, tackifiers, and grinding media. Based on the total weight of the coating composition by weight, these additives may be present in a combined amount of 0 to 10%, 0.001% to 5%, 1% to 4%, or 2% to 3%.

[0060] Based on the total weight of the coating composition by weight, the coating composition of the present invention may have a solids content of 28% to 80%, 40% to 70%, or 50% to 60%.

[0061] The coating composition of the present invention can be prepared by a process comprising the following steps: blending the copolymer additive with the binder and other optional components (e.g., pigments and / or extenders as described above). The components in the coating composition can be mixed in any order to provide the coating composition of the present invention. Any of the above optional components can also be added to the coating composition during or before mixing to form the coating composition. When the coating composition contains pigments and / or extenders, preferably the pigments and / or extenders are mixed with a dispersant to form a slurry of the pigments and / or extenders.

[0062] The coating composition of the present invention (usually an aqueous coating composition) can be used to remove formaldehyde in various applications. The coating composition can provide good formaldehyde emission reduction characteristics to meet the requirements of the JC / T 1074-2008 standard (the standard of the China Building Materials Industry for the purification performance of air-purifying coatings), as indicated by a formaldehyde emission reduction (FA) efficiency of 75% or higher, preferably 78% or higher, 80% or higher, 85% or higher, or even 90% or higher.

[0063] The present invention also includes a method for removing aldehydes from aldehyde-containing air using the coating composition of the present invention, the method comprising: applying the coating composition to a substrate; and drying or allowing to dry the applied aqueous coating composition to form a film (i.e., a coating). After the coating composition of the present invention has been applied to a substrate, the coating composition can be dried at room temperature (15°C - 35°C) or an elevated temperature (e.g., 35°C - 80°C).

[0064] Compared with a similar coating composition lacking a copolymer additive but containing an acetoacetoxy-functional binder, the coating composition of the present invention can also provide less yellowing for the coating film prepared therefrom. For example, the coating composition can provide a coating film with reduced or lower yellowing, as indicated by a Δb of less than 0.5 after 7 days of thermal aging at 50°C as determined by the test methods described in the following Examples section.

[0065] The coating composition of the present invention can be applied and adhered to various substrates. Examples of suitable substrates include wood, metal, plastic, foam, stone, elastic substrates, glass, textiles, concrete, or cement substrates. The coating composition preferably containing pigments is suitable for various applications, such as marine and protective coatings, automotive coatings, road marking paints, exterior insulation and finish systems (EIFS), roof adhesives, wood coatings, coil coatings, plastic coatings, powder coatings, can coatings, architectural coatings, and civil engineering coatings. The coating composition is particularly suitable for architectural coatings.

[0066] The coating composition of the present invention can be applied to a substrate by conventional means including brushing, dipping, roll coating, and spraying, preferably by spraying. Standard spraying techniques and spraying equipment can be used, such as air atomizing spraying, air spraying, airless spraying, high volume low pressure spraying, and electrostatic spraying (such as electrostatic bell application) and manual or automatic methods.

[0067] Examples

[0068] Some embodiments of the present invention will now be described in the following Examples, where all parts and percentages are by weight unless otherwise indicated.

[0069] CELLOSIZE QP-15000-H hydroxyethyl cellulose, ROCIMA 363, and KATHON LXE biocide, and Ti-Pure R-706 (TiO 2 ) pigment are all available from The Dupont Company.

[0070] CC-700 extender (CaCO 3)Available from Guangfu Building Materials Group (China).

[0071] The DB-80 extender (calcined clay) is available from Shanxi Jinyang Calcined Kaolin Ltd. (China).

[0072] The Texanol coalescent is available from Eastman Chemical Company.

[0073] ECOSURF TM BD-109 nonionic alcohol ethoxylate surfactant, OROTAN TM 1124 dispersant, 2-methyl-2-amino-propanol (AMP-95) used as a neutralizing agent, ROPAQUE TM Ultra E opaque polymer and ACRYSOL TM The RM-2020 NPR thickener is available from The Dow Chemical Company (ECOSURF, OROTAN, ROPAQUE, and ACRYSOL are trademarks of The Dow Chemical Company).

[0074] (2-Acetoacetoxy)ethyl methacrylate monomer (AAEM) is available from Eastman Chemical Company.

[0075] Butyl acrylate (BA), 2-ethylhexyl acrylate (EHA), methyl methacrylate (MMA), and methacrylic acid (MAA) are available from hanghai LangYuan Chemical Co.,Ltd.

[0076] The FOAMATER NXZ antifoaming agent, DISPONIL FES 32 anionic surfactant (fatty alcohol ether sulfate), DISPONIL LDBS 20 surfactant (linear dodecylbenzene sulfonate), and MPEGMA 350 (methyl polyethylene glycol methacrylate) are available from BASF Global Corporation.

[0077] The RHODAFAC RS-610-A25 surfactant (phosphate ester based on branched alcohol ethoxylate) is available from SolvayCompany.

[0078] Ethylidene urea methacrylate (MEEU), ammonium persulfate (APS), sodium bisulfite (SBS), monoethanolamine (MEA), sodium salt of ethylenediaminetetraacetic acid (EDTA), sodium carbonate (Na 2 CO 3 ), ferrous sulfate (FeSO 4 ·7H 2 O) used as a promoter can all be obtained from Shanghai Chemical Reagent Co., Ltd.

[0079] The following standard analytical equipment and methods were used in the examples to determine the properties and characteristics described herein:

[0080] GPC analysis

[0081] GPC analysis was generally carried out by Agilent 1200 (Agilent Technologies (China) Co., Ltd.) to determine the molecular weight.

[0082] To measure the molecular weight of the copolymer additive, the copolymer additive sample was dissolved in dimethylformamide (DMF) / 2% formic acid (FA) (volume / volume) (v / v) at a concentration of 2 milligrams per milliliter (mg / mL). The resulting sample solution was left overnight and then filtered through a 0.45 μm polytetrafluoroethylene (PTFE) membrane before GPC analysis. GPC analysis was carried out using the following conditions: one PSS GRAM guard column and two PSS GRAM linear columns in series (8.0×300 mm, 10 μm); column temperature: 50 °C; mobile phase: DMF / 2% FA (volume / volume); flow rate: 1.0 mL / minute (min); injection volume: 100 μL; detector: Agilent refractive index detector, 50 °C; and calibration curve: PL polyethylene glycol narrow standards with molecular weights in the range of 542,500 g / mol to 1,010 g / mol, using a polynomial 3 fit.

[0083] To measure the molecular weight of the binder, the binder sample (Binder-1 or Binder-2) was dissolved in tetrahydrofuran (THF) / 5% formic acid (FA) at a concentration of 3 mg / mL. The resulting sample solution was filtered through a 0.45 μm PTFE membrane before GPC analysis. GPC analysis was performed using the following conditions: one pre-column and two Mixed B columns (7.5×300 mm); column temperature: 35 °C; mobile phase: THF / 5% FA; flow rate: 1.0 mL / min; injection volume: 50 μL; detector: Agilent refractive index detector, 35 °C; and calibration curve: PL polystyrene (PS) narrow standards (part number: 2010-0101), with PS equivalent molecular weights in the range of 2329000 g / mol to 580 g / mol.

[0084] Solid content

[0085] The solid content of the copolymer additive or binder sample was measured as follows: Weigh 0.7 ± 0.1 g of the sample (the wet weight of the sample is denoted as "W1"), place the sample in an aluminum dish (the weight of the aluminum dish is denoted as "W2") in an oven at 150 °C for 25 minutes, then cool to room temperature and weigh the aluminum dish with the dried sample, and the total weight is denoted as "W3". "W3 - W2" refers to the dry weight or solid weight of the sample. The solid content was calculated as (W3 - W2) / W1 * 100%.

[0086] Hydrolytic stability of copolymer additives

[0087] The degree of hydrolysis of the sample was characterized using the acetone content of the copolymer additive sample. For each test sample, at least two vials of the sample were tested for comparison. One vial was placed at room temperature (15 °C - 35 °C) for 1 day, and then the initial acetone level was measured. Another vial was placed in an oven at 80 °C for thermal aging for 1 day, and then the acetone level after thermal aging was measured and recorded as the final acetone level. For each test sample, two specimens were used and tested to give the average acetone level. The absolute difference between the initial acetone level and the final acetone level was defined as "Δ acetone level", based on the weight of the copolymer additive by weight, in parts per million (ppm). An acceptable Δ acetone level is <400 ppm.

[0088] The initial and final acetone levels of the sample were measured by headspace gas chromatography - flame ionization detector (GC - FID) as follows:

[0089] Weigh the sample to be tested (2 g) and place it in a GC container to run headspace GC, so as to test the acetone concentration in the sample. Set the oven in the headspace (Agilent G1888 headspace sampler) to 40 °C (vial equilibration time: 60 minutes). The GC-FID conditions are as follows: Instrument: Agilent 6890N gas chromatography system with a DB-5 column (30 m × 0.32 mm ID × 1.0 μm film); Carrier gas flow rate: helium carrier gas, a constant flow rate of 2.0 ml / min; Oven: 40 °C, held for 5 minutes, heated to 250 °C at a rate of 15 °C / minute, held for 0 minutes, total run time: 19 minutes; Inlet (injection temperature: 200 °C, split ratio: 5:1; temperature: 250 °C, H 2 Flow rate: 40 mL / min, air flow rate: 450 mL / min, make-up flow rate: 45 mL / min).

[0090] Formaldehyde emission reduction (FA) efficiency

[0091] Evaluate the FA efficiency characteristics of the coating composition according to the JC / T 1074-2008 standard. The FA efficiency is required to reach 75% or higher (≥75%) after 24 hours to meet the requirements of JC / T 1074-2008. The higher the FA efficiency, the better the FA emission reduction performance.

[0092] Coating film yellowing test

[0093] Use a 100 μm film casting machine to scrape the coating composition onto a black and white chart and dry it in a horizontal position for one day. Use a spectrophotometer to test the b value of the resulting coating film, denoted as "b 初始 ". Then place the coating film in an oven at 50 °C for 7 days, and then test the b value, denoted as "b 最终 ". The Δb value (Δb) is determined by the following formula: Δb = b 最终 - b 初始 . An acceptable yellowing performance is Δb < 0.5. The smaller the Δb value, the less yellowing.

[0094] Synthesis of Binder-1

[0095] A monomer emulsion was prepared by combining BA (343.22 g), EHA (419.66 g), MMA (737.92 g), MAA (39 g), MEEU (20.28 g), deionized (DI) water (450 g), and RS-610-A25 surfactant (25%, 111.07 g) and emulsifying under stirring. Then, FES 32 surfactant (30%, 7.8 g) and DI water (710 g) were charged into a five-liter multi-necked flask equipped with a mechanical stirring device. The contents of the flask were heated to 84 °C under a nitrogen atmosphere. Na 2 CO 3 (2.03 g) in DI water (33.82 g) was added to the stirred flask, followed by the monomer emulsion (59.61 g), an aqueous solution of ferrous sulfate (0.01 g) mixed with sodium salt of EDTA (0.03 g) in DI water (7.0 g), and then an aqueous solution of sodium persulfate (SPS) (4.68 g) in DI water (28.08 g). The remaining monomer emulsion, an aqueous solution of SBS (1.18 g) in DI water (102 g), and aqueous solutions of SPS (1.56 g) and Na 2 CO 3 (4.21 g) in DI water (98 g) were gradually added to the flask while maintaining the flask temperature at 87 °C. The container holding the monomer emulsion and the feed pipe leading to the flask were rinsed with DI water (56.16 g), and the rinse solution was added back to the flask. Then the reaction mixture was cooled to room temperature. During the cooling of the reaction mixture, an aqueous solution of tert-butyl hydroperoxide (70%, 2.17 g) and SBS (1.45 g) in DI water was added to the flask. The obtained dispersion was neutralized to a specific pH with 8% NaOH solution and adjusted to the target solid content given in Table 1 with DI water.

[0096] Synthesis of Binder-2

[0097] A monomer emulsion was prepared by combining BA (916.11 g), MMA (552.8 g), AAEM (78.34 g), MAA (23.49 g), DI water (307.17 g), and LDBS 20 surfactant (21%, 52.80 g) and emulsifying under stirring. Then, LDBS20 surfactant (21%, 21.52 g) and DI water (972.04 g) were charged into a five-liter multi-necked flask equipped with a mechanical stirring device. The materials in the flask were heated to 87 °C under a nitrogen atmosphere. Na 2 CO 3(4.69 g), and then an aqueous solution of monomer emulsion (69.56 g) and APS (4.68 g) in DI water (53.82 g) was added. Then the remaining monomer emulsion was gradually added to the flask within 65 minutes while maintaining the flask temperature at 87 °C. The container holding the monomer emulsion and the feed tube leading to the flask were rinsed with DI water (37.44 g), and the rinsing liquid was added back to the flask. Then the reaction mixture was cooled to 65 °C. Then, ferrous sulfate (0.01 g) mixed with sodium salt of EDTA (0.01 g) in DI water (4 g) was added to the flask. During the cooling of the reaction mixture, an aqueous solution of tert-butyl hydroperoxide (70%, 0.8 g) and SBS (0.8 g) in DI water was added to the flask. The obtained dispersion was neutralized with MEA to a specific pH and adjusted to the target solid content given in Table 1 with DI water.

[0098] Synthesis of N-(acetoacetyl)aminoethyl methacrylate (N-AAEM)

[0099] Methacrylic anhydride (107.1 g, 0.695 mol) was slowly added to a solution of N-(2-hydroxyethyl)acetoacetamide (77.6 g, 0.535 mol) in anhydrous THF (200 mL). Then pyridine (42.3 g, 43 mL, 0.535 mol) was slowly added to the mixture while stirring at 0 °C. The obtained yellow solution was stirred at 0 °C for 5 hours and then allowed to warm to room temperature under stirring to complete the reaction. Thin layer chromatography (TLC) confirmed the completion of the reaction. After the obtained mixture was cooled to 0 °C, 450 mL of HCl (1 M) was slowly added to the cooled mixture and stirred for a while. Then the organic layer was separated, washed twice with water (100 mL), dried over anhydrous sodium sulfate, and then anhydrous sodium sulfate was removed by filtration. Butylated hydroxytoluene (BHT) (120 mg) was added to the obtained organic layer, and then it was concentrated under reduced pressure at 25 °C. The residue was purified by flash chromatography (silica gel column; mobile phase: petroleum ether:ethyl acetate = 1:1) to obtain a white solid (65 g, yield: 57%) containing 300 ppm of BHT. By 1 1H nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of the obtained product (2-(acetoacetamido)ethyl methacrylate), where the peaks had the following chemical shifts: 6.15 ppm, 5.60 ppm, and 1.956 ppm (hydrogens on the carbon-carbon double bond); 4.25 ppm and 3.59 ppm (hydrogens on the methylene group attached to oxygen or nitrogen); 3.435 ppm and 2.26 ppm (hydrogens on the acetoacetate group).

[0100] Example (Ex) 1 copolymer additive

[0101] First, an aqueous solution of monomers was prepared by mixing MEEU (112.5 g) and the N - AAEM (12.5 g) prepared above with DI water (112.5 g). DI water (50 g) was added to a 500 mL reactor equipped with a mechanical stirrer, a condenser, a thermometer, and a nitrogen purge line. When the reaction temperature was raised to 78 °C, a promoter solution of ferrous sulfate (0.001 g) in DI water (0.48 g) was added to the reaction vessel, followed by the addition of a solution of SBS (0.95 g) in DI water (1.89 g). After 2 minutes, the aqueous solution of monomers obtained above, an aqueous solution of SPS (10%, 11.1 g), and an aqueous solution of SBS (40%, 32 g) were gradually added to the reactor at 78 °C over 90 minutes. After the addition of these aqueous solutions was completed, the reactor was cooled to 65 °C, and an aqueous solution of SPS (3%, 9.6 g) was added to the reactor to expel residual monomers. Then, the reactor was cooled to room temperature. The copolymer additive obtained was neutralized with AMP - 95 to a specific pH value given in Table 1.

[0102] Ex 2-5 copolymer additives

[0103] Ex 2 - 5 were carried out according to the synthesis procedure in Ex 1 above, except that the monomer compositions used are given in Table 1. The final pH value of the copolymer additives obtained was adjusted to the specific values given in Table 1 with AMP - 95.

[0104] Comparative (Comp) ExA-C copolymer additives

[0105] Comp Ex A - C were carried out according to the synthesis procedure in Ex 1 above, except that the monomer compositions used are given in Table 1. The final pH value of the copolymer additives obtained was adjusted to 7 to 10 given in Table 1.

[0106] The properties of the copolymer additives obtained above are given in Table 1. The hydrolysis stability of these copolymer additives was evaluated according to the above tests, and the Δacetone levels are given in Table 1. As shown in Table 1, all the copolymer additives of Ex 1 - 5 showed good hydrolysis stability, as indicated by a Δacetone < 400 ppm after thermal aging at 80 °C for 1 day. In contrast, the comparative copolymer additives of Comp Ex A - C prepared by using AAEM instead of N - AAEM showed unacceptable hydrolysis stability, as indicated by a Δacetone higher than 400 ppm after thermal aging.

[0107] Table 1. Composition and properties of binders and copolymer additives

[0108]

[0109] 1 by weight based on the total weight of the monomer 2 Determine the solids content as described above; 3 δacetone after 1 day of thermal aging at 80 °C, by weight based on the weight of the copolymer additive (in ppm); 4 Determine Mw by the above GPC.

[0110] Paint 1-5 and comparative paint A-E coating compositions

[0111] Based on the formulations given in Table 2, use the copolymer additive and binder thus prepared to prepare coating compositions, Paint 1, and Comparative Paints A and B. Mix the components in the grinding stage at a speed of 1,000 revolutions per minute (rpm) using a high-speed Cowles disperser. Then add the components in the thinning stage and mix at a speed of 500 rpm using a conventional stirrer to obtain the coating composition.

[0112] Prepare the coating compositions of Paints 2-5 and Comparative Paints C-E based on the same procedure as the preparation of Paint 1 above, except that the dosage and / or type of the copolymer additive used are given in Table 3 and adjust the water added to each coating composition so that the total amount of each coating composition is equal to 1,000 g.

[0113] Evaluate the properties of the resulting coating compositions according to the above FA efficiency and yellowing test methods, and the results are given in Table 3.

[0114] Table 2. Coating compositions

[0115] gram Comparative paint A Comparative paint B Paint 1 Grinding Water 116.2 116.2 116.2 CELLOSIZE QP-15000-H 2 2 2 AMP-95 2 2 2 Propylene glycol 10 10 10 ECOSURF BD-109 surfactant 2 2 2 FOAMATER NXZ defoamer 2 2 2 OROTAN 1124 dispersant 6 6 6 Ti-Pure R-706 200 200 200 CC-700 extender 120 120 120 DB-80 extender 60 60 60 ROCIMA 363 biocide 2 2 2 Total grinding materials 522.2 522.2 522.2 Thinning Water 70 70 70 Binder-1 323 323 Binder-2 300 Copolymer additive 18.9 Texanol 8 8 8 ROPAQUE Ultra E 40 40 40 FOAMATER NXZ defoamer 1 1 1 KATHON LXE 1.5% biocide 1 1 1 ACRYSOL RM-2020NPR 12 12 12 Water 22.8 45.8 3.9 Total 1000 1000 1000

[0116] As shown in Table 3, the coating compositions of Paints 1-5 containing the Ex 1-5 copolymer additives all provided an FA efficiency higher than 75%, meeting the FA requirements of JC / T 1074-2008. Comparative Paint A provided an FA efficiency far lower than 75%. Comparative Paint B containing the acetoacetoxy-functional binder-2 provided an FA efficiency of 82%, however, it exhibited unacceptable yellowing characteristics (Δb = 0.75) after thermal aging at 50 °C for 7 days. Compared with Comparative Paints A and B, Paints 1-5 provided the required FA efficiency without yellowing problems (Δb value < 0.5). Comparative Paints D and E containing 0.2 wt% of the copolymer additives of Comp Ex B and C respectively showed an FA efficiency lower than 75% and did not meet the requirements of JC / T 1074-2008. In contrast, Paint 4 containing the copolymer additive of Ex 4 with the same additive loading provided a much higher FA efficiency (81.8%). Even when using a low level of 0.08 wt% of the copolymer additive of Ex 3, the resulting Paint 3 still gave an FA efficiency of 75.1%, meeting the FA requirements. Comparative Paint C containing 0.04 wt% of the copolymer additive of Ex 3 failed the JC / T 1074-2008 test. Paint 5 containing 0.2 wt% of the copolymer additive of Ex 5 at a low pH (3.5) still provided an FA efficiency as high as 90.6%, indicating that the copolymer additives of the present invention can be used at low pH values while providing high FA efficiency.

[0117] Table 3. Coating compositions and properties

[0118]

[0119] * wt% refers to the dry weight of the copolymer additive relative to the total weight of the coating composition. The "dry weight" in this article is calculated by multiplying the wet weight of the polymer additive by the solid content of this polymer additive. N / A - Not applicable.

Claims

1. A copolymer additive, the copolymer additive comprising a copolymer having a weight average molecular weight of 1,000 g / mol to 10,000 g / mol and water, wherein, based on the weight of the copolymer by weight, the copolymer comprises: 4% to 60% of structural units of an acetoacetamide-functional monomer having the structure of formula (I): wherein R 1 is selected from the following structures: wherein R 2 , R 4 , R 8 , R 10 , R 12 and R 13 are each independently an alkylene group having 2 to 20 carbon atoms, R 3 , R 5 , R 6 , R 7 and R 11 are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, R 9 is hydrogen or an alkyl group having 1 to 20 carbon atoms, and X is –O– or –NH–; and 40% to 96% of structural units of a ureido monomer.

2. The copolymer additive according to claim 1, wherein the acetoacetamide-functional monomer is an (meth)acrylic acid acetoacetamidoalkyl ester.

3. The copolymer additive according to claim 1, wherein the acetoacetamide-functional monomer is selected from the group consisting of: acetoacetamidoethyl methacrylate, acetoacetamidoethyl acrylate, acetoacetamidoethyl (meth)acrylamide, acetoacetamidoethyl maleate, or a mixture thereof.

4. The copolymer additive according to any one of claims 1-3, wherein the ureido monomer is selected from the group consisting of: or a mixture thereof.

5. The copolymer additive according to any one of claims 1-3, wherein, based on the weight of the copolymer by weight, the copolymer comprises 8% to 25% of the structural units of the acetoacetamide-functional monomer and 75% to 92% of the structural units of the ureido monomer.

6. The copolymer additive according to any one of claims 1-3, wherein the copolymer has a weight average molecular weight of 2,000 g / mol to 7,000 g / mol.

7. The copolymer additive according to any one of claims 1-3, the copolymer additive having a pH value of 2 to 10.

8. A coating composition, the coating composition comprising: a binder having a weight average molecular weight of 100,000 g / mol or greater, and 0.08% to 3% by dry weight of the copolymer additive according to any one of claims 1-7, based on the total weight of the coating composition.

9. The coating composition according to claim 8, wherein the binder comprises a homopolymer of acrylic acid, a styrene-acrylic copolymer, a vinyl acetate-acrylic copolymer, or a mixture thereof.

10. The coating composition according to claim 8 or 9, the coating composition comprising 0.15% to 2.2% of the copolymer additive by dry weight, based on the total weight of the coating composition.

11. The coating composition according to claim 8 or 9, wherein, based on the total weight of the coating composition by weight, the coating composition comprises 0.04% to 0.4% of the structural units of the acetoacetamide-functional monomer.

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