Composite resin, aqueous resin dispersion, coating composition, and aqueous coating material

Abstract

The purpose of the present invention is to provide a composite resin, an aqueous resin dispersion, a coating composition, and an aqueous coating material that provide a coating film having excellent coating film strength, heat resistance, water resistance, and solvent resistance. The composite resin according to the present invention is a composite resin of a urethane resin (A) having a structure derived from a linear diol (a1-1) having 8-11 carbon atoms and a (meth) acrylate resin (B).

Description

Technical Field

[0001] The invention relates to a composite resin, an aqueous resin dispersion, a coating composition and an aqueous coating material. This application claims priority based on Japanese Patent Application No. 2022-194631 filed in Japan on December 6, 2022, the contents of which are incorporated herein by reference. Background Art

[0002] In the past, in the field of coating materials such as coatings, inks, and adhesives, the transition from organic solvent-based coating materials to water-based coating materials has been sought from the perspective of environmental protection, safety, and sanitation. However, compared with organic solvent-based coating materials, water-based coating materials have problems of poor storage stability and coating film appearance, coating film strength, weather resistance, heat resistance, water resistance, solvent resistance, and pollution resistance. In recent years, in particular, excellent durability (weather resistance, heat resistance, water resistance, and solvent resistance) that is not easily affected by the use environment and the period of use has been required.

[0003] As a material for an aqueous coating material for solving various problems, an aqueous dispersion of a composite resin containing resins having different properties has been proposed. For example, Patent Document 1 describes an aqueous resin dispersion of polymer particles containing a urethane polymer and an acrylic polymer. The coating film coated with the water-based paint containing the water-based resin dispersion described in Patent Document 1 is excellent in adhesion to resin substrates such as ABS and metal substrates such as aluminum, and in tensile strength and hardness when formed into a film. However, there are still problems in terms of heat resistance and solvent resistance. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2013-209656 Summary of the invention Problems to be solved by the invention

[0005] An object of the present invention is to provide a composite resin, an aqueous resin dispersion, a coating composition and an aqueous coating material which can produce a coating film having excellent coating film strength, heat resistance, water resistance and solvent resistance. Technical solutions to the problem

[0006] That is, the gist of the present invention is as follows. [1] A composite resin comprising a polyurethane resin A and a (meth)acrylate resin B, wherein the polyurethane resin A has a structure derived from a linear diol (a1-1) having 8 to 11 carbon atoms. [2] The composite resin according to [1], wherein the acid value of the resin A is 15 to 60 mgKOH / g. [3] The composite resin according to [1] or [2], wherein the composite resin contains 20% by weight or more and 90% by weight or less of the linear diol (a1-1) based on the total weight of the resin A. [4] The composite resin according to [1] or [2], wherein the composite resin contains 10 to 90 wt % of the resin A relative to the total weight of the composite resin. [5] The composite resin according to [1] or [2], wherein the resin A has a chemical structure derived from a polycarbonate polyol. [6] The composite resin according to [1] or [2], wherein the diol (a1-1) has 10 carbon atoms. [7] The composite resin according to [1] or [2], wherein at least one of the polyurethane resin A and the (meth)acrylate resin B is made of a bio-derived raw material. [8] The composite resin according to [1] or [2], wherein the biomass degree is 20% or more. [9] An aqueous resin dispersion comprising the composite resin of [1] or [2].

[10] A coating composition comprising the composite resin of [1] or [2].

[11] An aqueous coating material comprising the composite resin of [1] or [2]. Effects of the Invention

[0007] According to the present invention, there are provided a composite resin, an aqueous resin dispersion, a coating composition and an aqueous coating material which can produce a coating film having excellent coating film strength, heat resistance, water resistance and solvent resistance. DETAILED DESCRIPTION

[0008] In the present specification, the numerical range represented by "to" means a range including the numerical values ​​before and after it. In addition, the upper limit and the lower limit of the numerical range can be arbitrarily combined. “(Meth)acrylate” is a general term for acrylate and methacrylate.

[0009] <Resin A: Polyurethane resin A> In the present invention, the polyurethane resin A is a resin obtained by reacting a polyol (a1) with a polyisocyanate (a2). A polyol is an organic compound having at least two hydroxyl groups in one molecule, and various polyols can be used. In the polyurethane resin A, by using a linear diol (a1-1) having 8 to 11 carbon atoms as at least a part of the polyol (a1), the polyurethane resin A has a structure derived from the linear diol (a1-1) having 8 to 11 carbon atoms. The linear diol (a1-1) having 8 to 11 carbon atoms refers to a diol having hydroxyl groups substituted on carbon atoms at both ends of a linear alkane having 8 to 11 carbon atoms. The linear diol (a1-1) having 8 to 11 carbon atoms includes 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,11-undecanediol. These may be used alone or in combination of two or more. From the viewpoint of improving the coating strength, heat resistance, water resistance, and solvent resistance of the obtained coating film, the carbon number is preferably 10, and 1,10-decanediol is more preferred.

[0010] In order to improve the coating strength, heat resistance, water resistance and solvent resistance of the obtained coating, the diol (a1-1) having 8 to 11 carbon atoms preferably contains 20% by weight or more, more preferably 35% by weight or more, and further preferably 45% by weight or more relative to the total weight of resin A. In addition, it is preferably 90% by weight or less, more preferably 80% by weight or less. The above upper and lower limits can be combined arbitrarily. For example, it can be 20% by weight or more and 90% by weight or less, it can also be 35% by weight or more and 90% by weight or less, and it can also be 45% by weight or more and 80% by weight or less.

[0011] From the viewpoint of the polymerizability of the composite resin and the stability of the obtained aqueous resin dispersion, a carboxyl group-containing diol such as dimethylol propionic acid or dimethylol butyric acid may be further used as the polyol (a1). From the viewpoint of the polymerizability of the composite resin and the stability of the obtained aqueous resin dispersion, the acid value of the polyurethane resin A is preferably 15 mgKOH / g or more, more preferably 20 mgKOH / g or more, and further preferably 30 mgKOH / g or more. On the other hand, from the viewpoint of the coating strength of the obtained coating film, it is preferably 60 mgKOH / g or less, and more preferably 50 mgKOH / g or less. The above upper and lower limits may be arbitrarily combined. For example, it may be 15 to 60 mgKOH / g or more, 20 to 60 mgKOH / g or more, or 30 to 50 mgKOH / g or more.

[0012] The acid value can be measured by a potentiometric titration method (JIS K 0070) using potassium hydroxide. As the mass of the sample, the "polyurethane resin amount" is used. In addition, for example, when potassium hydroxide is used in neutralization during the manufacture of polyurethane resin, salt exchange is not easy to occur, so it is sometimes difficult to measure using the above-mentioned JIS method. In this case, the "theoretical acid value" per gram of polyurethane resin can be calculated according to the following formula. Theoretical acid value (mgKOH / g) = (number of moles of acid-containing raw material added × 56.1 (KOH molecular weight) / polyurethane resin amount (g)) × 1000

[0013] As the polyol (a1), a diol (a1-2) having 7 or less or 12 or more carbon atoms or a branched diol can be used. Examples of the diol (a1-2) having 7 or less or 12 or more carbon atoms or having a branched chain include ethylene glycol, propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 2-methyl-1,3-propylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,5-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 1,7-heptanediol, 2,4-dimethyl-1,5-pentanediol, 2,3-dimethyl-1,5-pentanediol, 2-ethyl-1,5-pentanediol, 2-methyl-1,6-hexanediol, 3-methyl-1,6-hexanediol, 2-ethyl-1,6-hexanediol, 2-methyl-1,8-octanediol, 1,7-heptanediol, 1,7-heptanediol, 3-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, 4-methyl-1,8-octanediol, 1,9-nonanediol, 2-methyl-1,9-nonanediol, 3-methyl-1,9-nonanediol, 4-methyl-1,9-nonanediol, 1,10-decanediol, 2-methyl-1,10-decanediol, 3-methyl-1,10-decanediol, 4-methyl-1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, trimethylolpropane, trimethylolethane, glycerol, ε-caprolactone. These may be used alone or in combination of two or more.

[0014] It is preferable that the diol (a1-1) and the diol (a1-2) are contained in the polyurethane resin A as a structure derived from a reaction product obtained by reacting with the following compound. Examples of the reactants obtained by reacting with diol (a1-1) and diol (a1-2) include: polycarbonate polyols obtained by reacting with carbonates such as dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and propylene carbonate, and with phosgene; polyether diols obtained by addition polymerization with ethylene oxide, propylene oxide, tetrahydrofuran, etc.; and polyester polyols obtained by condensation polymerization with dicarboxylic acids such as adipic acid, sebacic acid, itaconic acid, maleic anhydride, terephthalic acid, and isophthalic acid. These may be used alone or in combination of two or more.

[0015] As the reaction product obtained by the reaction with the diol (a1-1) and the diol (a1-2), a polycarbonate polyol is preferred from the viewpoint of improving the coating strength, heat resistance, water resistance and solvent resistance of the obtained coating film. In addition, a polycarbonate polyol having a structure derived from a linear diol (a1-1) having 8 to 11 carbon atoms is more preferred, and a polycarbonate polyol having a structure derived from 1,10-decanediol is further preferred. Examples of the polycarbonate polyol include trade names “BENEBiOL (registered trademark; hereinafter the same) NL1010DB”, “BENEBiOL NL1030DB”, “BENEBiOL NL2010DB”, “BENEBiOL NL2030DB”, “BENEBiOL NL2070DB”, “BENEBiOL NL2000D”, and “BENEBiOL NL3010DB” manufactured by Mitsubishi Chemical Corporation. The number average molecular weight of the polycarbonate polyol is preferably 500 to 3500, more preferably 500 to 2500, and even more preferably 1000 to 2500 in order to improve the heat resistance, water resistance, and solvent resistance of the resulting coating film.

[0016] In addition, other high molecular weight polyols (a1-3) can be used as polyols (a1-3). Other high molecular weight polyols (a1-3) are polyols having repeating units, for example, polyether polyols such as polyethylene glycol, polypropylene glycol, polycaprolactone polyol, polytetramethylene ether polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, and poly(meth)acrylate polyol. These may be used alone or in combination of two or more.

[0017] Examples of the polyisocyanate (a2) include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-2,5-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene diisocyanate. Acid esters, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylphenylene diisocyanate, diisopropylphenylene diisocyanate, 1-methyl-3,5-diethylphenylene diisocyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3,5-triethylbenzene-2,4-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methyl-naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7- diisocyanate, 1,1-dinaphthyl-2,2'-diisocyanate, biphenyl-2,4'-diisocyanate, biphenyl-4,4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate and other aromatic polyisocyanates; tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate Aliphatic or alicyclic polyisocyanates such as isocyanate, 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-bis(isocyanate methyl)cyclohexane, 1,4-bis(isocyanate methyl)cyclohexane, lysine diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate and 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate. These may be used alone or in combination of two or more.

[0018] From the viewpoint of the physical properties and polymerizability of the resulting coating film, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and trimethylhexamethylene diisocyanate are preferred.

[0019] From the perspective of the obtained coating film strength, the usage ratio of polyol (a1) and polyisocyanate (a2) is preferably polyol (a1):polyisocyanate (a2) = 1.0:1.0 to 1.0:2.0, more preferably 1.0:1.2 to 1.0:1.8, and further preferably 1.0:1.3 to 1.0:1.7, in terms of equivalent ratio.

[0020] The polyurethane resin A can also be produced using raw materials derived from organisms (derived from biomass). The raw materials derived from organisms are obtained from oils and fats obtained from crops such as sugars represented by corn, sugar cane, and sugar beet; oil palm, soybean (Glycine max), rapeseed, and castor. For example, biomass diols such as ethylene glycol, 1,4-butanediol, 1,3-propylene glycol, and 1,10-decanediol derived from organisms; biomass polyols having biomass dibasic acids and biomass diols as structural units; and biomass polyols such as glycerol and castor oil polyol derived from organisms. Moreover, as a diisocyanate derived from a biological substance, dimer acid diisocyanate (DDI), pentamethylene diisocyanate, octamethylene diisocyanate, and decamethylene diisocyanate are mentioned, for example.

[0021] Examples of the bio-derived raw material include trade names “BENEBiOL NL1010DB”, “BENEBiOL NL1030DB”, “BENEBiOL NL2010DB”, “BENEBiOL NL2030DB”, “BENEBiOL NL2070DB”, “BENEBiOL NL2000D”, and “BENEBiOL NL3010DB” manufactured by Mitsubishi Chemical Corporation.

[0022] The carbamate formation reaction for producing the polyurethane resin A can be carried out in the absence of a solvent, but in order to carry out the reaction uniformly, for example, ethers such as dioxane; ketones such as acetone and methyl ethyl ketone; amides such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone; or organic solvents that are inactive to other isocyanate groups and have a high affinity for water may also be used. (Meth)acrylate monomers and other radical polymerizable monomers which are non-reactive to isocyanate groups, that is, do not contain active hydrogen groups, may be present when preparing the polyurethane resin A. In this case, the reaction system can be diluted by the monomers, so that the reaction proceeds more uniformly.

[0023] The reaction for producing the polyurethane resin A may be carried out at about 50 to 100° C. for about 0.5 to 20 hours. In this way, a polyurethane resin having an isocyanate group at the terminal can be obtained.

[0024] As the catalyst used in the production of the polyurethane resin A, a catalyst generally used in a urethanization reaction can be used. For example, dibutyltin dilaurate can be mentioned. From an environmental point of view, it is preferred not to use a catalyst.

[0025] Part or all of the carboxyl groups of the polyurethane resin A are preferably neutralized with at least one selected from ammonia and primary, secondary and tertiary amine compounds (hereinafter, "ammonia and primary, secondary and tertiary amine compounds" are collectively referred to as "amine compounds"). This can improve the dispersibility of the polyurethane resin in the aqueous medium and improve the physical properties of the resulting coating film. The neutralization reaction may be performed in any process as long as it is after the polyurethane resin is produced and before it is dispersed in an aqueous medium, but is preferably performed in the first neutralization process described below and, if necessary, in the second neutralization process described below.

[0026] Examples of the primary amine compound include primary amine compounds such as methylamine, ethylamine, butylamine, methanolamine, ethanolamine, propanolamine, and butanolamine; and primary aminoalkanol compounds such as aminomethylpropanol, aminoethylpropanol, aminopropylpropanol, aminomethylbutanol, aminomethylpentanol, and aminoethylbutanol. Examples of the secondary amine compound include secondary amine compounds such as dimethylamine, diethylamine, methylethylamine, dibutylamine, and diethanolamine. Examples of the tertiary amine compound include tertiary amine compounds such as trimethylamine, triethylamine, tributylamine, and triethanolamine. From the viewpoint of improving the physical properties of the obtained coating film, it is preferred to use a tertiary amine compound.

[0027] From the perspective of the dispersion stability of the obtained polyurethane resin A, the total amount of the amine compound used is preferably 0.7 equivalents or more, more preferably 0.8 equivalents or more, and further preferably 1 equivalent or more relative to the amount of carboxyl groups in the polyurethane resin as the total amount used in the first neutralization step and the second neutralization step described later. That is, it is preferred that the carboxyl groups in the polyurethane resin A are neutralized by the amine compound by 70% or more, more preferably 90% or more, and further preferably 100%. If it is 0.7 equivalents or more, the dispersion stability of the obtained polyurethane resin A tends to be easy to become good. On the other hand, it is preferably 2.0 equivalents or less, and more preferably 1.8 equivalents or less. If it is 2.0 equivalents or less, the amine compound remains in the emulsion in small amounts, so the water resistance of the obtained coating tends to become good. The above upper and lower limits may be arbitrarily combined. For example, it may be 0.7 to 2.0 equivalents, 0.8 to 2.0 equivalents, or 1 to 1.8 equivalents.

[0028] Examples of the aqueous medium for dispersing the polyurethane resin A include water and a mixed solution of water and an organic solvent such as ethanol that is compatible with water. From an environmental point of view, water is preferred.

[0029] The polyurethane resin A may be subjected to a chain extension reaction as required. Examples of the chain extender used in this case include compounds having a plurality of active hydrogens that can react with isocyanate groups and water (including water as an aqueous medium for dispersing the polyurethane resin A).

[0030] Examples of the compound having a plurality of active hydrogen atoms that can react with an isocyanate group include polyols having 1 to 8 carbon atoms and polyamine compounds having 1 to 8 carbon atoms. Examples of the polyol having 1 to 8 carbon atoms include ethylene glycol and diethylene glycol. Examples of the polyamine compound having 1 to 8 carbon atoms include diamines such as ethylenediamine, hexamethylenediamine, and isophoronediamine.

[0031] The chain extension reaction of the polyurethane resin A is when the polyurethane resin A and the mixed solution containing the aforementioned (meth)acrylate monomer not containing an active hydrogen group and / or other radical polymerizable monomers are emulsified and dispersed in the aqueous medium to obtain an emulsion. When water is used as the aqueous medium, the chain extension reaction of the polyurethane resin A may partially occur in the polymerization step of the aforementioned (meth)acrylate monomer not containing an active hydrogen group and / or other radical polymerizable monomers. In addition, when the chain extension reaction is actively carried out, a chain extender may be added after the emulsification and dispersion to carry out the chain extension reaction.

[0032] When a chain extension reaction is performed, in order to distinguish the polyurethane resin obtained by the chain extension reaction, the polyurethane resin before the chain extension reaction is sometimes referred to as a urethane prepolymer.

[0033] <Resin B: (meth)acrylate resin B> In the present invention, the (meth)acrylate resin B is a resin obtained by polymerizing a polymer component (b) containing a (meth)acrylate monomer (b1). The polymer component (b) may further contain other free radical polymerizable monomers (b2) as long as it contains 50% by weight or more of the (meth)acrylate monomer (b1).

[0034] Examples of the (meth)acrylate monomer (b1) include alkyl (meth)acrylates having an alkyl group having 1 to 22 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate. ; (meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and polypropylene glycol (meth)acrylate; multifunctional (meth)acrylates, such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate; (meth)acrylates, such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, and tert-butylcyclohexyl (meth)acrylate ) cycloalkyl acrylate; (meth)acrylates having a hydrolyzable silyl group such as γ-(meth)acryloxypropylmethyldimethoxysilane and γ-(meth)acryloxypropyltrimethoxysilane; (meth)acrylates having an alkyl terminal polyoxyalkylene group such as methoxypolyethylene oxide mono(meth)acrylate; (meth)ethylene oxide acrylates such as glycidyl (meth)acrylate; (meth)acrylates having a carbonyl group such as diacetone acrylamide; 1,2,2,6,6-pentamethyl-4-piperidinyl (meth)acrylate, 2,2,6,6-pentamethyl-4-piperidinyl (meth)acrylate, (meth)acrylates having a light stabilizing effect, such as 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, etc.; (meth)acrylates having ultraviolet absorption, such as 2-aminoethyl (meth)acrylate; (meth)acrylate aminoalkyl esters, such as (meth)acrylic acid 2-ester; (meth)acrylates having an amide group, such as (meth)acrylic acid amide; (meth)acrylates having a metal, such as zinc di(meth)acrylate; and other (meth)acrylates, such as benzyl (meth)acrylate, isobornyl (meth)acrylate, and methoxyethyl (meth)acrylate.

[0035] As other free radical polymerizable monomers (b2), for example, there can be mentioned: free radical polymerizable monomers having a carboxyl group, such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate; free radical polymerizable monomers having a phosphate group, such as 2-methacryloyloxyethyl acid phosphate; free radical polymerizable monomers having sulfonates, such as styrene sulfonate; aromatic vinyl monomers such as styrene and methylstyrene; conjugated diene monomers such as 1,3-butadiene and isoprene; and other free radical polymerizable monomers such as vinyl acetate, vinyl chloride, ethylene, and (meth)acrylonitrile.

[0036] From the viewpoint of the polymerizability of the composite resin, an alkyl (meth)acrylate having an alkyl group having 1 to 22 carbon atoms is preferred, an alkyl (meth)acrylate having an alkyl group having 1 to 6 carbon atoms is more preferred, and methyl (meth)acrylate is further preferred. From the viewpoint of polymerizability of the composite resin, the structural unit derived from methyl (meth)acrylate preferably accounts for 10 wt% or more, more preferably 20 wt% or more, and preferably 100 wt% or less, based on the total weight of the (meth)acrylate resin B. The above upper and lower limits may be arbitrarily combined. For example, it may be 10 to 100% by weight, or 20 to 100% by weight.

[0037] The (meth)acrylate resin B can be produced similarly to the polyurethane resin A using a raw material derived from a biological source. For example, examples of biologically derived (meth)acrylates include lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, isobornyl (meth)acrylate, and octyl (meth)acrylate.

[0038] <Composite resin> In the present invention, the composite resin is a composite resin of a polyurethane resin A and a (meth)acrylate resin B, and refers to a resin having the polyurethane resin A and the (meth)acrylate resin B. Specifically, the same particle contains a polyurethane resin A and a (meth)acrylate resin B. Preferably, the particle is a core-shell type particle, wherein the shell portion is the polyurethane resin A, and more preferably the core portion is the (meth)acrylate resin B. In addition, the composite resin of the present invention can be produced by polymerizing a polymerization component (b) containing a (meth)acrylate monomer (b1) in the presence of a polyurethane resin A (or a urethane prepolymer). From the viewpoint of the coating strength, heat resistance, water resistance and solvent resistance of the obtained coating film, the ratio of the polyurethane resin A to the (meth)acrylate resin B in the composite resin is preferably 10 to 90 wt % of the polyurethane resin A and the (meth)acrylate resin B, respectively, relative to the total weight of the composite resin, more preferably 20 to 80 wt % of the polyurethane resin A and the (meth)acrylate resin B, respectively, and further preferably 30 to 70 wt % of the polyurethane resin A and the (meth)acrylate resin B, respectively.

[0039] In the present invention, the "biomass ratio" is an index indicating the mixing ratio of raw materials derived from organisms and raw materials other than biological sources, and is determined by the weight ratio of raw materials derived from organisms in the composite resin and is represented by the following formula. Biomass content (%) = dry weight of biological raw material (g) / dry weight of composite resin (g) × 100

[0040] The biomass degree of the composite resin of the present invention is preferably 20% or more, more preferably 25% or more. When the biomass content is high, an environmentally friendly composite resin can be formed.

[0041] The composite resin can be prepared, for example, by preparing a mixed solution containing a polyurethane resin A (or a urethane prepolymer) and a polymer component (b) (containing a (meth) acrylic acid ester monomer (b1)), then emulsifying and dispersing the mixed solution in an aqueous medium, and polymerizing the polymer component (b) containing the (meth) acrylic acid ester monomer (b1) in the emulsion, thereby obtaining an aqueous resin dispersion containing the composite resin. In addition, in this process, a chain extension reaction of the urethane prepolymer can be carried out as needed.

[0042] The mixed liquid comprising a polyurethane resin A (or a urethane prepolymer) and a polymer component (b) (comprising a (meth)acrylate monomer (b1)) is prepared by neutralizing at least a portion of the carboxyl groups to make the polyurethane resin A (or a urethane prepolymer) water-dispersible when the polyurethane resin A has a carboxyl group, and the polymer component (b) comprising the (meth)acrylate monomer (b1) is prepared so as to be uniformly dispersed in an aqueous medium. The time of adding the polymer component (b) comprising the (meth)acrylate monomer (b1) is not particularly limited.

[0043] For example, the polymerization component (b) containing the (meth)acrylate monomer (b1) may be added before neutralizing at least a portion of the carboxyl groups of the polyurethane resin A (or urethane prepolymer), or the polymerization component (b) containing the (meth)acrylate monomer (b1) may be added after neutralizing at least a portion of the carboxyl groups of the polyurethane resin A (or urethane prepolymer). Alternatively, a part or all of the polymerizable component (b) containing a (meth)acrylate monomer (b1) may be mixed with a mixture containing a polyol (a1) and a polyisocyanate (a2) as raw materials of the polyurethane resin A (or urethane prepolymer), and the polyol (a1) and the polyisocyanate (a2) may be reacted in the presence of the polymerizable component (b) containing the (meth)acrylate monomer (b1) to produce the polyurethane resin A (or urethane prepolymer). When the remaining amount of the polymerizable component (b) containing the (meth)acrylate monomer (b1) is added after the production of the polyurethane resin A (or urethane prepolymer), the polymerizable component (b) containing the (meth)acrylate monomer (b1) may be added at any time before, at the same time, or after the carboxyl groups of the polyurethane urethane resin A (or urethane prepolymer) are neutralized.

[0044] A method of obtaining a polyurethane resin A (or a urethane prepolymer) by reacting a polyol (a1) with a polyisocyanate (a2) in the presence of a polymerizable component (b) comprising a (meth)acrylate monomer (b1) is preferred because the polyurethane resin (or urethane prepolymer) and the polymerizable component (b) comprising a (meth)acrylate monomer (b1) can be mixed more uniformly.

[0045] The concentration of the mixed solution of the polyurethane resin A (or urethane prepolymer) and the polymerized component (b) containing the (meth) acrylate monomer (b1) is not particularly limited, and the amount of non-volatile components in the aqueous dispersion composition finally obtained is preferably set to 20% by weight or more, and more preferably set to 30% by weight or more. If it is 20% by weight or more, the drying time can be shortened. On the other hand, the amount of non-volatile components in the aqueous dispersion composition finally obtained is preferably set to an amount of 70% by weight or less, and more preferably set to 60% by weight or less. If it is set to 70% by weight or less, the preparation of water dispersibility becomes easy, and the dispersion stability tends to become good. It should be noted that the concentration of the mixed solution of the polyurethane resin A (or urethane prepolymer) and the polymerization component (b) containing the (meth)acrylate monomer (b1) is equivalent to the absolute concentration of the composite resin of the polyurethane resin A and the (meth)acrylic resin B in the aqueous resin dispersion, coating composition and aqueous coating material of the present invention.

[0046] When all the carboxyl groups of the polyurethane resin A (or the carbamate prepolymer) are not neutralized, from the viewpoint of dispersion stability, it is preferred to add the aforementioned amine compound to a mixed solution of the polyurethane resin A (or the carbamate prepolymer) and a polymerization component (b) comprising a (meth)acrylate monomer (b1) to neutralize at least a part of the carboxyl groups of the polyurethane resin A (or the carbamate prepolymer), thereby obtaining a neutralized product of the polyurethane resin A (or the carbamate prepolymer) (hereinafter, this step is referred to as the "first neutralization step").

[0047] From the viewpoint of dispersion stability, the amount of carboxyl groups neutralized in the first neutralization step is preferably 0.5 equivalent or more, more preferably 0.55 equivalent or more, relative to all carboxyl groups of the polyurethane resin A (or urethane prepolymer). When the amount of carboxyl groups neutralized in the first neutralization step is 0.7 equivalents or more, the second neutralization step described below may not be performed. On the other hand, when the amount is less than 0.7 equivalents, the second neutralization step described below may be performed as necessary.

[0048] Next, a mixed solution of the neutralized polyurethane resin A (or urethane prepolymer) and the polymerized component (b) containing the (meth)acrylate monomer (b1) is emulsified and dispersed in an aqueous medium to obtain an emulsified dispersion (hereinafter, this step is referred to as "emulsification step"). There is no particular limitation on the method for adding an aqueous medium to a mixed solution of a neutralized product of a polyurethane resin A (or a urethane prepolymer) and a polymer component (b) comprising a (meth)acrylate monomer (b1). The aqueous medium may be added dropwise to a mixed solution of a neutralized product of a polyurethane resin A (or a urethane prepolymer) and a polymer component (b) comprising a (meth)acrylate monomer (b1) to disperse the mixture, or the mixed solution of a neutralized product of a polyurethane resin A (or a urethane prepolymer) and a polymer component (b) comprising a (meth)acrylate monomer (b1) may be added dropwise to an aqueous medium to disperse the mixture.

[0049] The temperature of the emulsification step is preferably 0° C. or higher, and more preferably 10° C. or higher. On the other hand, it is preferably 80° C. or lower, and more preferably 60° C. or lower. The above upper and lower limits may be arbitrarily combined. For example, the temperature may be 0 to 80°C or 10 to 60°C. When the temperature in the emulsification step is within the above range, the denaturation of the polyurethane resin A (or the urethane prepolymer) can be suppressed.

[0050] Next, in the obtained emulsified dispersion, the polymerizable component (b) containing the (meth)acrylate monomer (b1) is polymerized to obtain an aqueous resin dispersion of the composite resin (hereinafter, this step is referred to as the "polymerization step"). The polymerization step can be carried out by a common polymerization method according to the polymerizable component (b) containing the (meth)acrylate monomer (b1) used, for example, by adding a free radical polymerization initiator to the obtained emulsified dispersion.

[0051] As the free radical polymerization initiator, a commonly used free radical polymerization initiator can be used, for example, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyanovaleric acid and the like azobis(isobutyronitrile); persulfate initiators such as sodium persulfate, potassium persulfate, ammonium persulfate and the like; organic peroxide initiators such as tert-butyl hydroperoxide, dilauroyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate and the like. A redox polymerization initiator composed of an organic peroxide initiator, a persulfate initiator and a reducing agent such as ascorbic acid, bleaching powder or a metal sulfite may also be used. From the viewpoint of the polymerizability of the polymerizable component (b) containing the (meth)acrylate monomer (b1), the amount of the free radical polymerization initiator used is preferably 0.1 to 5% by weight, more preferably 0.5 to 2% by weight, relative to the polymerizable component (b) containing the (meth)acrylate monomer (b1).

[0052] From the viewpoint of polymerization rate, the polymerization temperature of the polymerization step is preferably 10 to 80° C., more preferably 30 to 60° C. After the heat generation is completed, the polymerization is completed by maintaining the temperature at about 40 to 90° C. for about 30 minutes to 3 hours. Thus, an aqueous resin dispersion of the mixed resin is obtained.

[0053] Between the emulsification step and the polymerization step and after the polymerization step, at least a portion of the polyurethane resin A (or urethane prepolymer) (including a neutralized product of the polyurethane resin A (or urethane prepolymer); the same applies hereinafter) may be chain extended as needed. In addition, a portion of the polyurethane resin A (or urethane prepolymer) may be chain extended between the emulsification step and the polymerization step, and at least a portion of the polyurethane resin A (or urethane prepolymer) remaining without chain extension in the chain extension step may be chain extended after the polymerization step. The chain extension reaction of the polyurethane resin A (or urethane prepolymer) occurs slowly in the emulsified dispersion due to water as the dispersion medium, and therefore the chain extension reaction also occurs during the polymerization step. In addition, the aforementioned amine compound may be used to further neutralize at least a portion of the carboxyl groups of the polyurethane resin A (or urethane prepolymer) between the emulsification step and the polymerization step or after the polymerization step (hereinafter, this step is referred to as the "second neutralization step"). By bringing the degree of neutralization to a predetermined range, the storage stability of the obtained aqueous resin dispersion is improved.

[0054] From the perspective of storage stability of the obtained aqueous resin dispersion, the amount of the amine compound used in the second neutralization step is preferably 0.7 equivalents or more relative to all carboxyl groups of the polyurethane resin A (or urethane prepolymer) plus the amount used in the first neutralization step. It should be noted that when 0.7 equivalents or more of the amine compound has been used in the first neutralization step, the second neutralization step may be omitted.

[0055] The amine compound used in the first and second neutralization steps is preferably used in the form of an aqueous solution or an aqueous dispersion from the viewpoint of easy addition and mixing. The neutralized mixed resin may be dissolved or dispersed in water alone, a mixed solvent of a polar organic solvent and water, or an organic solvent. Examples of the polar organic solvent include alcohols, ketones, and other organic solvents. Examples of the alcohols include alcohols having 1 to 8 carbon atoms such as ethanol, propanol, isopropanol, butanol, benzyl alcohol, and phenylethanol; and divalent or higher alcohols such as alkylene glycols such as glycerol, ethylene glycol, and propylene glycol. Examples of ketones include acetone and methyl ethyl ketone. Examples of other organic solvents include low boiling hydrocarbons such as pentane; ethers such as diethyl ether and dimethoxymethane; glycol ethers such as monoethylene glycol monoalkyl ether, diethylene glycol monoalkyl ether, and triethylene glycol monoalkyl ether; and esters such as methyl acetate.

[0056] In the production process of the composite resin, an emulsifier may be used as necessary. Examples of the emulsifier include ionic surfactants such as anionic, cationic, and zwitterionic surfactants, and nonionic surfactants. By using an emulsifier, the generation of agglomerates in the production process can be suppressed. In addition, by using an emulsifier, the storage stability of the obtained aqueous resin dispersion may be improved.

[0057] The aqueous resin dispersion, coating composition and aqueous coating material of the present invention contain the composite resin of the present invention. The coating film obtained from the composite resin, aqueous resin dispersion, coating composition or aqueous coating material of the present invention has excellent heat resistance, water resistance and solvent resistance.

[0058] <Coating composition> The coating composition of the present invention preferably contains the composite resin of the present invention and water as a dispersion medium for the composite resin. The coating composition of the present invention may contain, as required, for example, a resin other than the composite resin of the present invention, a curing agent, a pigment, a pigment dispersant, a leveling agent, an anti-sagging agent, a matting agent, an antioxidant, a heat resistance improving agent, a slip agent, an antifouling agent, a plasticizer, an organic solvent, a curing catalyst, a dispersant, an anti-settling agent, a defoaming agent, a thickener, an ultraviolet absorber, a light stabilizer, and a surface conditioner.

[0059] Examples of the resin other than the composite resin of the present invention include acrylic resins, polyurethane resins, polyester resins, polyolefin resins, epoxy resins, polyvinyl alcohol resins, and polyvinyl pyrrolidone resins, and emulsions and water-soluble resins of these resins are particularly preferred. When a resin other than the composite resin of the present invention is contained, the content of the composite resin of the present invention in the coating composition (solid content) is 10 to 99% by mass, preferably 50 to 98% by mass, 80 to 97% by mass.

[0060] <Water-based coating material> When used as an aqueous coating material, it preferably contains the composite resin of the present invention and water as a dispersion medium for the composite resin. The coating composition of the present invention may contain, as required, resins other than the composite resin of the present invention, viscosity regulators, film-forming aids, curing agents, plasticizers, preservatives, mildew inhibitors, algaecides, antibacterial agents, defoamers, leveling agents, coupling agents, surfactants, pigment dispersants, anti-settling agents, anti-sagging agents, wetting agents, catalysts, curing accelerators, dehydrating agents, defoamers, matting agents, antifreeze agents, ultraviolet absorbers, antioxidants, light stabilizers, water, and solvents.

[0061] When a resin other than the composite resin of the present invention is contained, the content of the composite resin of the present invention in the aqueous coating material (solid content) is 10 to 99% by mass, preferably 50 to 98% by mass, 80 to 97% by mass.

[0062] <Base Material> The substrate (article to be coated) of the coating composition and the water-based coating material of the present invention is not particularly limited, and the coating composition and the water-based coating material can be applied to various substrates to form a coating film.

[0063] Examples of the substrate include outer panels of automobile bodies, automobile interior substrates, outer panels of home appliances, cement mortar, slate boards, gypsum boards, extruded boards, foamed concrete, metals, glass, tiles, asphalt, wood, waterproof rubber materials, plastics, calcium silicate substrates, vinyl chloride sheets, FRP (fiber reinforced plastics), natural leather, synthetic leather, and fibers.

[0064] Specifically, for example, interior and exterior decoration of passenger cars / trucks / motorcycles / buses, construction materials, interior and exterior decoration of buildings, window frames, window glass, structural members, panels, exterior decoration of mechanical devices and articles, bridges, guardrails, tents, plastic greenhouses, blinds, roofing materials, residential equipment, refrigerators, air conditioners, televisions, lighting fixtures, kitchen supplies, and functional fibers.

[0065] <Method for forming coating film> As a method for applying the aqueous resin dispersion, coating composition and aqueous coating material of the present invention to the surface of a substrate, various coating methods such as air spray coating, airless spray coating, rotary atomization coating, curtain coating, roller coating, rod coating, air knife coating, brush coating, and dipping coating can be cited. The coating amount is preferably an amount that makes the thickness of the coating film after drying be 0.1 to 200 μm, more preferably 10 to 100 μm, and particularly preferably 20 to 70 μm.

[0066] When the applied aqueous resin dispersion, coating composition and aqueous coating material are dried, a coating film is formed. Drying can be performed at room temperature of 0 to 40°C or by heating at a temperature above 0 to 40°C. From the perspective of film-forming properties, the drying temperature is preferably 20 to 100°C.

[0067] The coating film can be formed by heating the coating film by a known method by heating the coating film by heating the coating film. For example, a heating furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace can be used as the heating method. Example

[0068] Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. "Parts" in the examples refer to "parts by weight". The physical property tests of the water-based coating materials in the examples were carried out according to the following methods.

[0069] <Raw materials> [Polyol (a1)] @NL2000D: A polycarbonate diol having a number average molecular weight of 2,000 and containing 87.2% by weight of a structure derived from 1,10-decanediol (manufactured by Mitsubishi Chemical Corporation, trade name "BENEBiOL NL2000D") NL2070DB: a polycarbonate diol having a number average molecular weight of 2,000 and containing 69.9% by weight of a structure derived from 1,10-decanediol (manufactured by Mitsubishi Chemical Corporation, trade name "BENEBiOL NL2070DB") NL2030DB: a polycarbonate diol having a number average molecular weight of 2,000 and containing 37.1% by weight of a structure derived from 1,10-decanediol (manufactured by Mitsubishi Chemical Corporation, trade name "BENEBiOL NL2030DB") NL1030DB: a polycarbonate diol having a number average molecular weight of 1,000 and containing 37.6% by weight of a structure derived from 1,10-decanediol (manufactured by Mitsubishi Chemical Corporation, trade name "BENEBiOL NL1030DB") ·1,10DDO: 1,10-decanediol (manufactured by Toyokoku Oil Co., Ltd.) @980N: Polycarbonate diol containing a high molecular weight diol having a carbonate group and a structural unit obtained by removing two hydroxyl groups from 1,6-hexanediol (manufactured by Tosoh Corporation, trade name "NIPPORAN 980N") Bis-MPA: diol having carboxylic acid (manufactured by Perstorp, dimethylolpropionic acid)

[0070] [Polyisocyanate (a2)] IPDI: Isophorone diisocyanate (manufactured by Evonik Japan Co., Ltd., trade name VESTANAT IPDI) ·H 12 MDI: Hydrogenated diphenylmethane diisocyanate (manufactured by Evonik Japan Ltd., trade name VESTANAT H12MDI)

[0071] [(Meth)acrylate (b1)] ·MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation) @BA: n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation) AA: acrylic acid (80 wt% aqueous solution of acrylic acid, manufactured by Mitsubishi Chemical Corporation)

[0072] <Evaluation method> [Preparation of Cured Coating Film for Heat Resistance Evaluation] The aqueous resin dispersion obtained in the example was applied to a polypropylene plate so that the film thickness after drying was 300 μm, dried at room temperature for more than 24 hours, and peeled from the polypropylene plate to prepare a cured coating film for heat resistance evaluation. The prepared coating film for evaluation was cut into 2.5 cm×11 cm.

[0073] [Preparation of coating composition for evaluation of water resistance and solvent resistance] To 100 parts of the aqueous resin dispersion obtained in Example, a mixed solution of 0.35 parts of a silicone substrate wetting agent (TEGO(R) Wet260 manufactured by Evonik Japan Ltd.) and 3.15 parts of ion exchanged water was added to obtain a coating composition for evaluation.

[0074] [Preparation of Cured Coating Film for Evaluation of Water Resistance and Solvent Resistance] The obtained evaluation coating composition was applied on a black acrylic plate (manufactured by TP Giken Co., Ltd., with a plate thickness of 2 mm, a length of 150 mm, and a width of 70 mm) using a rod coater so that the film thickness after drying was 40 μm, dried at 80°C for 30 minutes, and then aged for more than 15 hours in an environment of 23°C×50%RH to prepare a cured coating film for evaluation of water resistance and solvent resistance.

[0075] [Evaluation method] (1) Heat resistance The obtained cured coating film for heat resistance evaluation was kept in a 50°C environment for 20 minutes, and then a load of 1 kg was applied in a 50°C environment for 1 hour, and the obtained elongation was evaluated according to the following criteria. A: Elongation is less than 10% B: Elongation greater than 10% and less than 40% C: Elongation greater than 40% D: Film formation is impossible. * Elongation (%) = (cured coating length after 1 hour - initial film length) / initial film length × 100

[0076] (2) Water resistance The obtained cured coating film for evaluating water resistance and solvent resistance was immersed in 23° C. water for 15 hours, and immediately after being taken out, the whitening degree ΔL of the coating film was measured using a colorimeter (manufactured by Konica Minolta Japan Co., Ltd., trade name CR-300) and evaluated according to the following criteria. A: ΔL is less than 2.0 B: ΔL is 5.0 or less C: ΔL greater than 5.0

[0077] (3) Solvent resistance (alcohol) One drop of a 95% ethanol solution was dropped on the obtained cured coating film for evaluating water resistance and solvent resistance at room temperature, and the appearance after 5 minutes was visually evaluated according to the following criteria. A: No whitening, shiny B: Slightly white, slightly dull C: White, dull

[0078] (4)Solvent resistance (toluene) One drop of a toluene solution was dropped on the obtained cured coating film for evaluating water resistance and solvent resistance under room temperature environment, and the appearance after 5 minutes was visually evaluated according to the following criteria. A: No whitening, shiny B: Slightly white, slightly dull C: White, dull

[0079] (Examples 1 to 7, Comparative Example 3) Into a four-necked flask equipped with a thermometer, a stirrer and a reflux condenser were added the components listed in the Resin A column of Tables 1 and 2, the components listed in the Resin B column and 0.008 parts of hydroquinone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polymerization inhibitor, and mixed at an internal temperature of 50°C, then heated to 90°C and reacted at this temperature for 3 hours to obtain a polyurethane resin A having an isocyanate group and a carboxyl group. Next, while maintaining the liquid temperature at 50° C., triethylamine was added as a neutralizing agent in an amount of 1 equivalent % relative to the carboxyl equivalent of the obtained polyurethane resin A for neutralization. Next, 179 parts of ion exchange water was added dropwise at 40° C. over 15 minutes to obtain a milky white and transparent dispersion. The obtained dispersion was maintained at 50° C., and at this temperature, 0.4 parts of tert-butyl hydroperoxide (LUPEROX TBH, manufactured by Arkema GIFU Co., Ltd.) as a polymerization initiator and 0.1 parts of L-ascorbic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a reducing agent were added to initiate polymerization of the (meth)acrylate. After the heat generation was completed, the temperature was further raised to 70° C. and maintained for 3 hours to obtain an aqueous resin dispersion of a composite resin of the polyurethane resin A and the (meth)acrylic resin B. The obtained aqueous resin dispersion was subjected to various evaluations. The results are shown in Tables 1 and 2.

[0080] (Comparative Example 1) Into a four-necked flask equipped with a thermometer, a stirrer and a reflux condenser, 88 parts of methyl ethyl ketone were added, and further, a specified amount of the components recorded in the Resin A column of Table 2 were added, respectively. After mixing at an internal temperature of 50°C, the temperature was raised to 80°C, and the mixture was reacted at this temperature for 10 hours to obtain a polyurethane resin having an isocyanate group and a carboxyl group. Next, while maintaining the liquid temperature at 50° C., triethylamine was added as a neutralizing agent in an amount of 1 equivalent % relative to the carboxyl equivalent of the obtained polyurethane resin for neutralization. Next, 276 parts of ion exchange water was added dropwise to the solution at 40° C. over 15 minutes to obtain a milky white and transparent dispersion. The obtained dispersion liquid was heated to 70° C. and maintained for 3 hours, and then heated to 80° C. and maintained for 3 hours to distill off methyl ethyl ketone, thereby obtaining an aqueous resin dispersion of a polyurethane resin. The obtained aqueous resin dispersion was subjected to various evaluations. The results are shown in Table 2.

[0081] (Comparative Example 2) In a four-necked flask equipped with a thermometer, a stirring device and a reflux condenser, 53 parts of ion-exchanged water, 0.71 parts of Emulsogen EPN 287 (manufactured by Clariant, a nonionic surfactant) and 1.79 parts of Emulsogen EPA 073 (manufactured by Clariant, an anionic surfactant) were added and mixed at an internal temperature of 75°C. Next, 39 parts of MMA, 59 parts of BA, 2.5 parts of 80% AA, 2.86 parts of Emulsogen EPN 287, 37.14 parts of Emulsogen EPA 073 and 40 parts of ion-exchanged water were mixed and stirred to obtain an emulsified monomer, and an initiator aqueous solution of 0.5 parts of potassium persulfate and 24.5 parts of ion-exchanged water was prepared. Then, while maintaining the internal temperature at 75°C, the emulsified monomer composition and the initiator aqueous solution were added dropwise over 3 hours and 30 minutes to carry out a polymerization reaction. After completion of the dropwise addition, 1.85 parts of a 10% aqueous ammonia solution was added, and the mixture was kept at 75° C. for 1.5 hours. Then, the reaction liquid was cooled to room temperature to obtain an aqueous resin dispersion of a (meth)acrylate resin. The obtained aqueous resin dispersion of the (meth)acrylate resin and the aqueous resin dispersion of the polyurethane resin obtained in Comparative Example 1 were blended so that the polyurethane resin and the (meth)acrylate resin were equal in weight to obtain a mixed aqueous resin dispersion of the polyurethane resin and the (meth)acrylate resin. The obtained aqueous resin dispersion was subjected to various evaluations. The results are shown in Table 2.

[0082] [Table 1]

[0083] [Table 2]

[0084] Comparative Example 1 in which no (meth)acrylic resin was used was inferior in heat resistance and water resistance. Comparative Example 2 in which the polyurethane resin and the (meth)acrylic resin were not composited was inferior in heat resistance, water resistance, and solvent resistance. Comparative Example 3 in which the polyurethane resin did not have a structure derived from the linear diol (a1-1) having 8 to 11 carbon atoms had poor film-forming properties at room temperature.

Claims

1. A composite resin comprising a polyurethane resin A and a (meth)acrylate resin B, wherein the polyurethane resin A has a structure derived from a linear diol (a1-1) having 8 to 11 carbon atoms.

2. The composite resin according to claim 1, in, The acid value of the resin A is 15 to 60 mgKOH / g.

3. The composite resin according to claim 1 or 2, in, The composite resin contains 20 wt % or more and 90 wt % or less of the linear diol (a1-1) based on the total weight of the resin A.

4. The composite resin according to claim 1 or 2, in, The composite resin contains 10 to 90 wt % of the resin A based on the total weight of the composite resin.

5. The composite resin according to claim 1 or claim 2, in, The resin A has a chemical structure derived from polycarbonate polyol.

6. The composite resin according to claim 1 or 2, in, The diol (a1-1) has 10 carbon atoms.

7. The composite resin according to claim 1 or 2, in, At least one of the polyurethane resin A and the (meth)acrylate resin B is made of a biologically derived raw material.

8. The composite resin according to claim 1 or 2, which has a biomass degree of 20% or more. 9 . An aqueous resin dispersion comprising the composite resin according to claim 1 or 2 . 10 . A coating composition comprising the composite resin according to claim 1 or 2.

11. An aqueous coating material comprising the composite resin according to claim 1 or 2.

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