WO2024122493A1 - Composite resin, aqueous resin dispersion, coating composition, and water-based coating material - Google Patents

Abstract

The purpose of the present invention is to provide: a composite resin which provides a coating film that has excellent coating film strength, heat resistance, water resistance, and solvent resistance; an aqueous resin dispersion; a coating composition; and a water-based coating material. A composite resin according to the present invention comprises: a polyurethane resin A that has a structure derived from a C8-11 straight chain diol (a1-1); and a (meth)acrylic resin B.

Description

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

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

Traditionally, in the field of coating materials such as paints, inks, and adhesives, efforts have been made to switch from organic solvent-based coating materials to water-based coating materials from the perspective of environmental conservation and safety and health. However, water-based coating materials have the problem of being inferior to organic solvent-based coating materials in terms of storage stability, coating film appearance, coating film strength, weather resistance, heat resistance, water resistance, solvent resistance, and contamination resistance. In recent years in particular, there has been a demand for excellent durability (weather resistance, heat resistance, water resistance, and solvent resistance) that is not easily affected by the usage environment or period of use.

As a material for an aqueous coating material to solve these various problems, an aqueous dispersion of a composite resin containing resins with 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.
A coating film applied with an aqueous paint containing the aqueous 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 problems with heat resistance and solvent resistance.

Japanese Patent Publication No. 2013-209656

The present invention aims to provide a composite resin, an aqueous resin dispersion, a paint composition, and an aqueous coating material that can provide a coating film with excellent coating film strength, heat resistance, water resistance, and solvent resistance.

That is, the present invention relates to the following.
[1] A composite resin of a polyurethane resin A having a structure derived from a linear diol (a1-1) having 8 to 11 carbon atoms and a (meth)acrylate resin B.
[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], containing the linear diol (a1-1) in an amount of 20% by weight or more and 90% by weight or less based on the total weight of the resin A.
[4] The composite resin according to [1] or [2], containing 10 to 90% by weight of the resin A based on 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 using a raw material of biological origin.
[8] The composite resin of [1] or [2], having a biomass content of 20% or more.
[9] An aqueous resin dispersion containing the composite resin of [1] or [2].
[10] A coating composition containing the composite resin of [1] or [2].
[11] An aqueous coating material containing the composite resin of [1] or [2].

The present invention can provide a composite resin, an aqueous resin dispersion, a paint composition, and an aqueous coating material that can provide a coating film with excellent coating film strength, heat resistance, water resistance, and solvent resistance.

In this specification, the numerical range indicated with "to" means a range including the numerical values before and after it. In addition, the upper and lower limits of the numerical range can be combined in any way.
"(Meth)acrylate" is a general term for acrylate and methacrylate.

<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). The 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 means a diol in which hydroxy groups are substituted on carbon atoms at both ends of a linear alkane having 8 to 11 carbon atoms. Examples of the linear diol (a1-1) having 8 to 11 carbon atoms include 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 film strength, heat resistance, water resistance, and solvent resistance of the resulting coating film, the alkyl group preferably has 10 carbon atoms, and 1,10-decanediol is more preferable.

The diol (a1-1) having 8 to 11 carbon atoms improves the coating strength, heat resistance, water resistance, and solvent resistance of the resulting coating film, so it is preferably contained in 20% by weight or more, more preferably 35% by weight or more, and even more preferably 45% by weight or more, based on the total weight of resin A. It is also preferably contained in 90% by weight or less, and more preferably 80% by weight or less. The above upper and lower limits can be combined in any manner. For example, it may be 20% by weight or more and 90% by weight or less, 35% by weight or more and 90% by weight or less, or 45% by weight or more and 80% by weight or less.

From the viewpoint of the polymerizability of the composite resin and the stability of the resulting aqueous resin dispersion, a carboxyl group-containing diol such as dimethylolalkanoic acid, for example, dimethylolpropionic acid or dimethylolbutanoic acid, may further be used as the polyol (a1).
The acid value of the polyurethane resin A is preferably 15 mgKOH/g or more, more preferably 20 mgKOH/g or more, and even more preferably 30 mgKOH/g or more from the viewpoint of the polymerizability of the composite resin and the stability of the resulting aqueous resin dispersion, while it is preferably 60 mgKOH/g or less, more preferably 50 mgKOH/g or less from the viewpoint of the coating film strength of the resulting coating film.
The upper and lower limits can be combined in any manner. For example, the concentration may be 15 to 60 mgKOH/g or more, 20 to 60 mgKOH/g or more, or 30 to 50 mgKOH/g or more.

The acid value can be measured according to potentiometric titration (JIS K 0070) using potassium hydroxide. The mass of the sample is the "amount of polyurethane resin." For example, when potassium hydroxide is used for neutralization during the production of polyurethane resin, salt exchange is less likely to occur, making measurement by the above JIS method difficult. In such cases, the "theoretical acid value" per gram of polyurethane resin can be calculated and used according to the following formula.
Theoretical acid value (mgKOH/g)=(number of moles of acid-containing raw material charged×56.1 (molecular weight of KOH)/amount of polyurethane resin (g))×1000

As the polyol (a1), a diol (a1-2) having 7 or less carbon atoms or 12 or more carbon atoms, or a branched diol may be used. Examples of the diol (a1-2) having 7 or less carbon atoms or 12 or more carbon atoms or being branched include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 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 1,7-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 ethyl-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, glycerin, and ε-caprolactone.
These may be used alone or in combination of two or more.

The diol (a1-1) and the diol (a1-2) are preferably contained in the polyurethane resin A as structures derived from reaction products obtained by reacting them with the following compounds.
Examples of the reaction products of the diol (a1-1) and the diol (a1-2) include polycarbonate polyols obtained by reacting a carbonate ester, such as dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, or propylene carbonate, with phosgene; polyether diols obtained by addition polymerization with ethylene oxide, propylene oxide, tetrahydrofuran, or the like; and polyester polyols obtained by polycondensation with a dicarboxylic acid, such as adipic acid, sebacic acid, itaconic acid, maleic anhydride, terephthalic acid, or isophthalic acid.
These may be used alone or in combination of two or more.

The reaction product of the diol (a1-1) and the diol (a1-2) is preferably a polycarbonate polyol from the viewpoint of improving the coating film strength, heat resistance, water resistance, and solvent resistance of the resulting coating film. Also, 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 even more preferred.
Examples of polycarbonate polyols include those available from Mitsubishi Chemical Corporation under the trade names “BENEBiOL (registered trademark; the same applies below) NL1010DB”, “BENEBiOL NL1030DB”, “BENEBiOL NL2010DB”, “BENEBiOL NL2030DB”, “BENEBiOL NL2070DB”, “BENEBiOL NL2000D”, and “BENEBiOL NL3010DB”.
The number average molecular weight of the polycarbonate polyol is preferably 500 to 3,500, more preferably 500 to 2,500, and even more preferably 1,000 to 2,500, in order to improve the heat resistance, water resistance, and solvent resistance of the resulting coating film.

In addition, other high molecular weight polyols (a1-3) may be used as the polyol (a1). The other high molecular weight polyols (a1-3) are polyols having repeating units, and examples thereof include polyether polyols such as polyethylene glycol, polypropylene glycol, polycaprolactone polyol, and polytetramethylene ether polyol; polybutadiene polyol; hydrogenated polybutadiene polyol; and poly(meth)acrylic acid ester polyol.
These may be used alone or in combination of two or more.

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, 1,3-dimethyl-4,6 -phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, 1-methyl-3,5-diethylbenzene 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 Aromatic polyisocyanates such as 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, and diphenylmethane-2,4-diisocyanate; tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3- Examples of the polyisocyanate include aliphatic or alicyclic polyisocyanates such as cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-di(isocyanatemethyl)cyclohexane, 1,4-di(isocyanatemethyl)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.

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.

From the viewpoint of the strength of the resulting coating film, the ratio of polyol (a1) to polyisocyanate (a2) used 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 even more preferably 1.0:1.3 to 1.0:1.7, in terms of equivalent ratio.

The polyurethane resin A may be produced using a biological (biomass-derived) raw material. The biological raw material is produced from sugars, such as corn, sugar cane, and sugar beet, and oils and fats obtained from crops, such as oil palm, soybean (Glycine max), rapeseed, and castor bean.
Examples of such biomass diols include ethylene glycol, 1,4-butanediol, 1,3-propanediol, and 1,10-decanediol, which are derived from living organisms; biomass polyols having biomass dibasic acids and biomass diols as building blocks; and biomass polyols such as glycerin and castor oil polyol, which are derived from living organisms.
Examples of biologically derived diisocyanates include dimer acid diisocyanate (DDI), pentamethylene diisocyanate, octamethylene diisocyanate, and decamethylene diisocyanate.

Examples of biologically derived raw materials include Mitsubishi Chemical Corporation's product names "BENEBiOL NL1010DB", "BENEBiOL NL1030DB", "BENEBiOL NL2010DB", "BENEBiOL NL2030DB", "BENEBiOL NL2070DB", "BENEBiOL NL2000D", and "BENEBiOL NL3010DB".

The urethane-forming reaction for producing the polyurethane resin A can be carried out without a solvent. However, 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 and N-methyl-2-pyrrolidone; or other organic solvents that are inactive to isocyanate groups and have high affinity for water may be used.
(Meth)acrylate monomers that are not reactive with isocyanate groups, i.e., that do not contain active hydrogen groups, and other radically polymerizable monomers may be present during the production of polyurethane resin A. In this case, the reaction system is diluted by the monomers, allowing the reaction to be carried out more uniformly.

The reaction to produce polyurethane resin A can be carried out at about 50 to 100°C for about 0.5 to 20 hours. This produces a polyurethane resin with isocyanate groups at its terminals.

The catalyst used in the production of polyurethane resin A may be any catalyst generally used in urethane reactions. For example, dibutyltin dilaurate may be used. From an environmental perspective, it is preferable not to use a catalyst.

It is preferable that the carboxyl groups in the polyurethane resin A are partially or entirely neutralized with at least one selected from ammonia and primary to tertiary amine compounds (hereinafter, "ammonia and primary to tertiary amine compounds" are collectively referred to as "amine compounds".) This can improve the dispersibility of the polyurethane resin in an aqueous medium and can also improve the physical properties of the resulting coating film.
This neutralization reaction can be carried out in any step after the production of the polyurethane resin and before dispersing it in an aqueous medium. Among these, it is preferable to carry out the neutralization reaction in the first neutralization step described below and, if necessary, in the second neutralization step described below.

Examples of the primary amine compounds 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 compounds include dimethylamine, diethylamine, methylethylamine, dibutylamine, and diethanolamine.
Examples of the tertiary amine compounds include trimethylamine, triethylamine, tributylamine, and triethanolamine.
From the viewpoint of improving the physical properties of the resulting coating film, a tertiary amine compound is preferably used.

From the viewpoint of the dispersion stability of the obtained polyurethane resin A, the total amount of the amine-based compound used is preferably 0.7 equivalents or more, more preferably 0.8 equivalents or more, and even more preferably 1 equivalent or more, relative to the amount of carboxyl groups of the polyurethane resin, as the total amount used in the first neutralization step and the second neutralization step described below. That is, the carboxyl groups in the polyurethane resin A are preferably neutralized by the amine-based compound by 70% or more, more preferably neutralized by 90% or more, and even more preferably neutralized by 100%. If it is 0.7 equivalents or more, the dispersion stability of the obtained polyurethane resin A tends to be 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, a small amount of the amine-based compound remains in the emulsion, so the water resistance of the obtained coating film tends to be good.
The upper and lower limits can be combined in any manner. For example, the amount may be 0.7 to 2.0 equivalents, 0.8 to 2.0 equivalents, or 1 to 1.8 equivalents.

Examples of aqueous media for dispersing polyurethane resin A include water and mixed solutions of water and an organic solvent that is compatible with water, such as ethanol. From an environmental perspective, water is preferred.

Polyurethane resin A can undergo a chain extension reaction as necessary. Examples of chain extenders used in this case include compounds having multiple active hydrogens that can react with isocyanate groups and water (including water as an aqueous medium for dispersing polyurethane resin A).

Examples of compounds having a plurality of active hydrogens capable of reacting with an isocyanate group include polyols having 1 to 8 carbon atoms and polyamine compounds having 1 to 8 carbon atoms.
Examples of polyols having 1 to 8 carbon atoms include ethylene glycol and diethylene glycol.
Examples of polyamine compounds having 1 to 8 carbon atoms include diamines such as ethylenediamine, hexamethylenediamine, and isophoronediamine.

When a mixed liquid containing polyurethane resin A and the above-mentioned (meth)acrylate monomer not containing an active hydrogen group and/or other radically polymerizable monomer is emulsified and dispersed in the aqueous medium to obtain an emulsion, if water is used as the aqueous medium, a chain extension reaction of polyurethane resin A may occur partially during the polymerization process of the above-mentioned (meth)acrylate monomer not containing an active hydrogen group and/or other radically polymerizable monomer. In addition, when the chain extension reaction is actively carried out, a chain extender can be added after the emulsion dispersion to carry out the chain extension reaction.

When a chain extension reaction is performed, the polyurethane resin before the chain extension reaction is sometimes called a urethane prepolymer to distinguish it from the polyurethane resin obtained by the chain extension reaction.

<Resin B: (Meth)Acrylate Resin B>
In the present invention, the (meth)acrylate resin B is a resin obtained by polymerizing a polymerization component (b) containing a (meth)acrylate monomer (b1). The polymerization component (b) may further contain another radical polymerizable monomer (b2) as long as it contains 50% by weight or more of the (meth)acrylate monomer (b1).

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, i-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (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; 2-hydroxyethyl (meth)acrylate; (meth)acrylates having a hydroxyl group, such as tert-butyl tert-butyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and polypropylene glycol (meth)acrylate; polyfunctional (meth)acrylates, such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate; cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, and t-butylcyclohexyl cycloalkyl (meth)acrylates such as cycloalkyl (meth)acrylate; (meth)acrylates having a hydrolyzable silyl group such as γ-(meth)acryloyloxypropylmethyldimethoxysilane and γ-(meth)acryloyloxypropyltrimethoxysilane; (meth)acrylates having an alkyl group-terminated polyalkylene oxide group such as methoxypolyethyleneoxide mono(meth)acrylate; (meth)acrylates having an oxirane group such as glycidyl (meth)acrylate; (meth)acrylates having a carbonyl group such as diacetoneacrylamide; 1,2,2,6,6-pentamethyl-4-piperidyl (meth)acrylate, 2,2,6,6-pentamethyl-4-piperidyl (meth)acrylate, Examples of such (meth)acrylates include (meth)acrylates with light stabilizing properties, such as methyl-4-piperidyl (meth)acrylate; (meth)acrylates with ultraviolet absorbing properties, such as 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole; aminoalkyl (meth)acrylates, such as 2-aminoethyl (meth)acrylate; (meth)acrylates with amide groups, such as (meth)acrylamide; (meth)acrylates with metals, such as zinc di(meth)acrylate; and other (meth)acrylates, such as benzyl (meth)acrylate, isobornyl (meth)acrylate, and methoxyethyl (meth)acrylate.

Other radical polymerizable monomers (b2) include, for example, radical polymerizable monomers having a carboxyl group, such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate; radical polymerizable monomers having a phosphoric acid group, such as 2-methacryloyloxyethyl acid phosphate; radical polymerizable monomers having a sulfonate, such as styrene sulfonate; aromatic vinyl monomers, such as styrene and methylstyrene; conjugated diene monomers, such as 1,3-butadiene and isoprene; vinyl acetate, vinyl chloride, ethylene, and (meth)acrylonitrile; and other radical polymerizable monomers.

From the viewpoint of the polymerizability of the composite resin, alkyl(meth)acrylates having an alkyl group with 1 to 22 carbon atoms are preferred, alkyl(meth)acrylates having an alkyl group with 1 to 6 carbon atoms are more preferred, and methyl(meth)acrylate is even more preferred.
From the viewpoint of the polymerizability of the composite resin, the (meth)acrylate-based resin B preferably contains 10% by weight or more of structural units derived from methyl (meth)acrylate, more preferably 20% by weight or more, and more preferably 100% by weight or less, based on the total weight of the (meth)acrylate-based resin B.
The upper and lower limits can be combined in any manner, for example, 10 to 100% by weight, or 20 to 100% by weight.

Like the polyurethane resin A, the (meth)acrylate resin B may be produced using raw materials of biological origin.
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.

<Composite resin>
In the present invention, the composite resin is a composite resin of a polyurethane resin A and a (meth)acrylate-based resin B, and means a resin having a polyurethane resin A and a (meth)acrylate-based resin B.
Specifically, the same particle contains polyurethane resin A and (meth)acrylate resin B. Core-shell type particles are preferred, and it is more preferred that the shell portion is polyurethane resin A and the core portion is (meth)acrylate resin B. 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 polyurethane resin A (or urethane prepolymer).
From the viewpoints of the coating film strength, heat resistance, water resistance, and solvent resistance of the resulting coating film, the ratio of polyurethane resin A and (meth)acrylate resin B in the composite resin is preferably 10 to 90 wt %, more preferably 20 to 80 wt %, and even more preferably 30 to 70 wt % of each of polyurethane resin A and (meth)acrylate resin B relative to the total weight of the composite resin.

In the present invention, the "biomass ratio" is an index representing the mixing ratio of biological raw materials and non-biological raw materials, and is determined by the weight ratio of biological raw materials in the composite resin and is represented by the following formula.
Biomass ratio (%)=dry weight of biological raw material (g)/dry weight of composite resin (g)×100

The biomass ratio of the composite resin of the present invention is preferably 20% or more, and more preferably 25% or more.
A high biomass content makes it possible to produce an environmentally friendly composite resin.

The composite resin can be obtained, for example, by preparing a mixed liquid containing polyurethane resin A (or urethane prepolymer) and a polymerization component (b) containing a (meth)acrylate monomer (b1), then emulsifying and dispersing this in an aqueous medium, and polymerizing the polymerization component (b) containing the (meth)acrylate monomer (b1) in the emulsion, thereby obtaining an aqueous resin dispersion containing the composite resin. In addition, during this process, a chain extension reaction of the urethane prepolymer can be carried out as necessary.

When the polyurethane resin A has carboxyl groups, the mixed liquid containing the polyurethane resin A (or urethane prepolymer) and the polymerization component (b) containing the (meth)acrylate monomer (b1) may be prepared in such a way that the polyurethane resin A (or urethane prepolymer) in which at least a portion of the carboxyl groups has been neutralized to make it water-dispersible, and the polymerization component (b) containing the (meth)acrylate monomer (b1) can be uniformly dispersed in the aqueous medium, and there is no particular restriction on the timing of addition of the polymerization component (b) containing the (meth)acrylate monomer (b1).

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 mixture containing polyol (a1) and polyisocyanate (a2), which are raw materials for polyurethane resin A (or urethane prepolymer), may be mixed with a part or all of polymerization component (b) containing (meth)acrylate monomer (b1), and the polyol (a1) and polyisocyanate (a2) may be reacted in the presence of polymerization component (b) containing (meth)acrylate monomer (b1) to produce polyurethane resin A (or urethane prepolymer). When the remaining amount of polymerization component (b) containing (meth)acrylate monomer (b1) is added after production of polyurethane resin A (or urethane prepolymer), the timing of addition of polymerization component (b) containing (meth)acrylate monomer (b1) may be any timing before, at the same time, or after neutralization of the carboxyl group of polyurethane urethane resin A (or urethane prepolymer).

The method of obtaining polyurethane resin A (or urethane prepolymer) by reacting polyol (a1) with polyisocyanate (a2) in the presence of polymerization component (b) containing (meth)acrylate monomer (b1) is preferred because it allows the polyurethane resin (or urethane prepolymer) to be mixed more uniformly with polymerization component (b) containing (meth)acrylate monomer (b1).

The concentration of the mixture of polyurethane resin A (or urethane prepolymer) and polymerization component (b) containing (meth)acrylate monomer (b1) is not particularly limited, but it is preferable that the amount of non-volatile components in the finally obtained aqueous dispersion composition is 20% by weight or more, more preferably 30% by weight or more. If it is 20% by weight or more, the drying time can be shortened. On the other hand, it is preferable that the amount of non-volatile components in the finally obtained aqueous dispersion composition is 70% by weight or less, more preferably 60% by weight or less. If it is 70% by weight or less, the preparation of water dispersibility becomes easy, and the dispersion stability tends to be good.
The concentration of the mixture of the polyurethane resin A (or urethane prepolymer) and the polymerization component (b) containing the (meth)acrylate monomer (b1) corresponds 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.

If all of the carboxyl groups of the polyurethane resin A (or urethane prepolymer) are not neutralized, from the viewpoint of dispersion stability, it is preferable to add the above-mentioned amine compound to a mixture of the polyurethane resin A (or urethane prepolymer) and the polymerization component (b) containing the (meth)acrylate monomer (b1) to neutralize at least a portion of the carboxyl groups of the polyurethane resin A (or urethane prepolymer) and obtain a neutralized product of the polyurethane resin A (or urethane prepolymer) (hereinafter, this step is referred to as the "first neutralization step").

From the viewpoint of dispersion stability, the amount of carboxyl groups neutralized in the first neutralization step is preferably 0.5 equivalents or more, and more preferably 0.55 equivalents or more, based on the total carboxyl groups in 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 does not need to be carried out. On the other hand, when the amount of carboxyl groups neutralized in the first neutralization step is less than 0.7 equivalents, the second neutralization step described below is carried out as necessary.

Next, a mixed liquid of the neutralized polyurethane resin A (or urethane prepolymer) and a polymerization component (b) containing a (meth)acrylate monomer (b1) is emulsified and dispersed in an aqueous medium to obtain an emulsion dispersion (hereinafter, this process is referred to as the "emulsification process").
The addition of an aqueous medium to a mixed liquid of a neutralized product of polyurethane resin A (or urethane prepolymer) and a polymerization component (b) containing a (meth)acrylate monomer (b1) is not particularly limited, and the aqueous medium may be added dropwise to the mixed liquid of a neutralized product of polyurethane resin A (or urethane prepolymer) and a polymerization component (b) containing a (meth)acrylate monomer (b1) to disperse the mixture, or the mixed liquid of a neutralized product of polyurethane resin A (or urethane prepolymer) and a polymerization component (b) containing a (meth)acrylate monomer (b1) may be added dropwise to the aqueous medium to disperse the mixture.

The temperature in the emulsification step is preferably 0° C. or higher, and more preferably 10° C. or higher, while it is preferably 80° C. or lower, and more preferably 60° C. or lower.
The upper and lower limits can be combined in any manner. For example, the temperature may be 0 to 80°C, or 10 to 60°C.
If the temperature in the emulsification step is within the above range, modification of the polyurethane resin A (or the urethane prepolymer) can be suppressed.

Then, in the obtained emulsion dispersion, the polymerization component (b) containing the (meth)acrylate monomer (b1) is polymerized to obtain an aqueous resin dispersion of a composite resin (hereinafter, this process is referred to as the "polymerization process"). The polymerization process can be carried out by a general polymerization method according to the polymerization component (b) containing the (meth)acrylate monomer (b1) used, and can be carried out, for example, by adding a radical polymerization initiator to the obtained emulsion dispersion.

As the radical polymerization initiator, a conventional radical polymerization initiator can be used. For example, azo initiators such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, and azobiscyanovaleric acid; persulfate initiators such as sodium persulfate, potassium persulfate, and ammonium persulfate; and organic peroxide initiators such as t-butyl hydroperoxide, dilauroyl peroxide, t-butylperoxy-2-ethylhexanoate, and t-butylperoxypivalate can be used.
A redox polymerization initiator may be used which is a combination of an organic peroxide initiator or a persulfate initiator with a reducing agent such as ascorbic acid, Rongalite, or a metal sulfite. From the viewpoint of the polymerizability of the polymerization component (b) containing the (meth)acrylate monomer (b1), the amount of the radical polymerization initiator used is preferably 0.1 to 5% by weight, more preferably 0.5 to 2% by weight, based on the polymerization component (b) containing the (meth)acrylate monomer (b1).

From the viewpoint of polymerization speed, the polymerization temperature in the polymerization process is preferably 10 to 80°C, more preferably 30 to 60°C. After the end of heat generation, the polymerization is completed by maintaining the temperature at about 40 to 90°C for about 30 minutes to 3 hours. This results in an aqueous resin dispersion of the mixed resin.

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 below) may be chain-extended, if necessary. Alternatively, between the emulsification step and the polymerization step, a portion of the polyurethane resin A (or urethane prepolymer) may be chain-extended, and after the polymerization step, at least a portion of the polyurethane resin A (or urethane prepolymer) that remains without being chain-extended in the chain-extension step may be chain-extended.
The chain extension reaction of the polyurethane resin A (or urethane prepolymer) occurs gradually even in the emulsion dispersion due to the presence of water as the dispersion medium, and therefore the chain extension reaction may also occur during the polymerization step.
In addition, between the emulsification step and the polymerization step, or after the polymerization step, at least a part of the carboxyl groups of the polyurethane resin A (or the urethane prepolymer) may be further neutralized with the above-mentioned amine-based compound (hereinafter, this step is referred to as the "second neutralization step"). By increasing the degree of neutralization to a predetermined range, the storage stability of the resulting aqueous resin dispersion is improved.

From the viewpoint of storage stability of the resulting aqueous resin dispersion, the amount of the amine compound used in the second neutralization step is preferably 0.7 equivalents or more, calculated as the total amount of the amine compound used in the first neutralization step relative to the total carboxyl groups of the polyurethane resin A (or urethane prepolymer). If 0.7 equivalents or more of the amine compound have already been used in the first neutralization step, this second neutralization step may be omitted.

The amine compound used in the first and second neutralization steps is preferably used as an aqueous solution or an aqueous dispersion from the viewpoint of facilitating addition and mixing. The neutralized mixed resin is 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 phenylethyl alcohol; and dihydric or higher alcohols, such as alkylene glycols, such as glycerin, ethylene glycol, and propylene glycol.
Examples of the ketones include acetone and methyl ethyl ketone.
Other organic solvents include, for example, low boiling point hydrocarbons such as pentane; ethers such as diethyl ether, dimethoxymethane; glycol ethers such as mono-, di-, or tri-ethylene glycol monoalkyl ether; and esters such as methyl acetate.

In the process of producing the composite resin, an emulsifier is used as necessary. Examples of the emulsifier include ionic surfactants such as anionic, cationic, and amphoteric surfactants, and nonionic surfactants.
The use of an emulsifier can suppress the formation of aggregates during the production process, and may also improve the storage stability of the resulting aqueous resin dispersion.

The aqueous resin dispersion, paint 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, paint composition, or aqueous coating material of the present invention has excellent heat resistance, water resistance, and solvent resistance.

<Paint 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 necessary, 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 improver, a slip agent, an antifouling agent, a plasticizer, an organic solvent, a curing catalyst, a dispersant, an anti-settling agent, an antifoaming agent, a thickener, an ultraviolet absorber, a light stabilizer, and a surface conditioner.

Examples of resins other than the composite resin of the present invention include acrylic resins, polyurethane resins, polyester resins, polyolefin resins, epoxy resins, polyvinyl alcohol resins, and polyvinylpyrrolidone 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 mass %, preferably 50 to 98 mass %, or 80 to 97 mass %.

<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 necessary, for example, a resin other than the composite resin of the present invention, a viscosity adjuster, a film-forming aid, a curing agent, a plasticizer, a preservative, an antifungal agent, an anti-algae agent, an antibacterial agent, an antifoaming agent, a leveling agent, a coupling agent, a surfactant, a pigment dispersant, an anti-settling agent, an anti-sagging agent, a wetting agent, a catalyst, a curing accelerator, a dehydrating agent, an antifoaming agent, a matting agent, an antifreeze agent, an ultraviolet absorber, an antioxidant, a light stabilizer, water, or a solvent.

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, or 80 to 97% by mass.

<Substrate>
There are no particular limitations on the substrate (object to be coated) for the paint composition or aqueous coating material of the present invention, and the composition can be applied to a variety of substrates to form a coating film.

Examples of substrates include exterior panels of automobile bodies, automobile interior substrates, exterior panels of household electrical appliances, cement mortar, slate boards, gypsum boards, extruded boards, foam concrete, metals, glass, porcelain tiles, asphalt, wood, waterproof rubber materials, plastics, calcium silicate substrates, PVC sheets, FRP (Fiber Reinforced Plastics), natural leather, synthetic leather, and fibers.

Specific examples include the interior and exterior of passenger cars, trucks, motorcycles and buses, building materials, interior and exterior of buildings, window frames, window glass, structural members, plate materials, exteriors of machinery and goods, bridges, guardrails, tents, vinyl greenhouses, blinds, roofing materials, housing equipment, refrigerators, air conditioners, televisions, lighting equipment, kitchen utensils and functional fibers.

<Method of forming coating film>
Methods for applying the aqueous resin dispersion, coating composition, and aqueous coating material of the present invention to the surface of a substrate include various coating methods such as air spray coating, airless spray coating, rotary atomization coating, curtain coating, roller coating, bar coating, air knife coating, brush coating, dipping coating, etc. The amount of coating is preferably an amount that results in a coating film having a thickness of 0.1 to 200 μm after drying, more preferably an amount that results in a thickness of 10 to 100 μm, and particularly preferably an amount that results in a thickness of 20 to 70 μm.

When the applied aqueous resin dispersion, paint composition, or aqueous coating material is dried, a coating film is formed. Drying may be performed at room temperature, between 0 and 40°C, or by heating to a higher temperature. From the viewpoint of film-forming properties, the drying temperature is preferably between 20 and 100°C.

By heat drying, the coating film can be heated by known means to form a 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 a heating means.

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.
In the examples, "parts" means "parts by weight".
The physical property tests of the aqueous coating materials in the examples were carried out by the methods described below.

<Ingredients>
[Polyol (a1)]
NL2000D: Polycarbonate diol containing 87.2% by weight of a structure derived from 1,10-decanediol having a number average molecular weight of 2,000 (manufactured by Mitsubishi Chemical Corporation, product name "BENEBiOL NL2000D")
NL2070DB: Polycarbonate diol containing 69.9% by weight of a structure derived from 1,10-decanediol having a number average molecular weight of 2,000 (manufactured by Mitsubishi Chemical Corporation, product name "BENEBiOL NL2070DB")
NL2030DB: Polycarbonate diol containing 37.1% by weight of a structure derived from 1,10-decanediol having a number average molecular weight of 2,000 (manufactured by Mitsubishi Chemical Corporation, product name "BENEBiOL NL2030DB")
NL1030DB: polycarbonate diol containing 37.6% by weight of a structure derived from 1,10-decanediol having a number average molecular weight of 1,000 (manufactured by Mitsubishi Chemical Corporation, product name "BENEBiOL NL1030DB") 1,10DDO: 1,10-decanediol (manufactured by Toyokuni Oil Mills 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, product name "Nippolan 980N")
Bis-MPA: Diol having a carboxylic acid (manufactured by Perstorp: Dimethylolpropionic acid)

[Polyisocyanate (a2)]
IPDI: Isophorone diisocyanate (manufactured by Evonik Japan Co., Ltd.: trade name VESTANAT IPDI)
_H12MDI : Hydrogenated diphenylmethane diisocyanate (manufactured by Evonik Japan Co., Ltd.: trade name VESTANAT H12MDI)

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

<Evaluation method>
[Preparation of cured coating film for evaluating heat resistance]
The aqueous resin dispersion obtained in the example was applied onto a polypropylene plate so that the film thickness after drying was 300 μm, and then dried at room temperature for 24 hours or more, and peeled off from the polypropylene plate to prepare a cured coating film for evaluation of heat resistance. The prepared coating film for evaluation was cut into a size of 2.5 cm x 11 cm.

[Preparation of coating composition for evaluating water resistance and solvent resistance]
A mixture of 0.35 parts of a siloxane-based substrate wetting agent (manufactured by Evonik Japan Ltd.: trade name TEGO® Wet 260) and 3.15 parts of ion-exchanged water was added to 100 parts of the aqueous resin dispersion obtained in the example, to obtain a coating composition for evaluation.

[Preparation of cured coating film for evaluation of water resistance and solvent resistance]
The obtained coating composition for evaluation was applied to a black acrylic plate (manufactured by TP Giken Co., Ltd., plate thickness 2 mm, length 150 mm, width 70 mm) using a bar coater so that the film thickness after drying would be 40 μm, and after drying at 80° C. for 30 minutes, it was aged in an atmosphere of 23° C. x 50% RH for 15 hours or more to produce a cured coating film for evaluation of water resistance and solvent resistance.

[Evaluation method]
(1) Heat resistance The obtained cured coating film for evaluating heat resistance was used and was held in a 50°C atmosphere for 20 minutes, and then subjected to a 1 kg load in a 50°C atmosphere for 1 hour. The heat resistance was evaluated based on the elongation according to the following criteria.
A: Elongation was 10% or less. B: Elongation was more than 10% and 40% or less. C: Elongation was more than 40%. D: Film formation was not possible.
*Elongation (%) = (length of cured coating film after 1 hour - initial film length) / initial film length x 100

(2) Water Resistance The obtained cured coating film for evaluating water resistance and solvent resistance was immersed in water at 23° C. for 15 hours, and the whitening degree ΔL of the coating film immediately after being removed was measured with a color difference meter (manufactured by Konica Minolta Japan, Inc.: product name CR-300) and evaluated according to the following criteria.
A: ΔL is 2.0 or less B: ΔL is 5.0 or less C: ΔL is greater than 5.0

(3) Solvent resistance (alcohol)
A drop of 95% ethanol solution was dropped onto the resulting 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, glossy B: Slightly whitened, slightly no gloss C: Whitened, no gloss

(4) Solvent resistance (toluene)
A drop of toluene solution was dropped onto the resulting cured coating film for evaluating water resistance and solvent resistance in an atmosphere at room temperature, and the appearance after 5 minutes was visually evaluated according to the following criteria.
A: No whitening, glossy B: Slightly whitened, slightly non-glossy C: Whitened, non-glossy

(Examples 1 to 7, Comparative Example 3)
The components shown in the Resin A column of Tables 1 and 2, the components shown in the Resin B column, and 0.008 parts of hydroquinone (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) as a polymerization inhibitor were added to a four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and the mixture was mixed at an internal temperature of 50° C., after which the temperature was raised to 90° C. and the mixture was allowed to react 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 equivalent weight of the carboxyl groups of the obtained polyurethane resin A to neutralize it. Next, 179 parts of ion-exchanged water was added dropwise at 40° C. over 15 minutes to obtain a milky white, transparent dispersion.
The obtained dispersion liquid was kept at 50°C, and at this temperature, 0.4 parts of t-butyl hydroperoxide (Luperox TBH, manufactured by Arkema Yoshitomi Co., Ltd.) as a polymerization initiator and 0.1 parts of L-ascorbic acid (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) as a reducing agent were added to initiate polymerization of (meth)acrylate.
After the heat generation had ceased, the temperature was further raised to 70° C. and maintained at that temperature for 3 hours, thereby obtaining an aqueous resin dispersion of a composite resin of polyurethane resin A and (meth)acrylic resin B.
The aqueous resin dispersion thus obtained was subjected to various evaluations, and the results are shown in Tables 1 and 2.

(Comparative Example 1)
88 parts of methyl ethyl ketone was added to a four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, and then the components shown in the Resin A column in Table 2 were added in predetermined amounts at an internal temperature of 50° C. After mixing, the mixture was heated to 80° C. and reacted at this temperature for 10 hours to obtain a polyurethane resin having isocyanate groups and carboxyl groups.
Next, while maintaining the liquid temperature at 50° C., triethylamine was added as a neutralizing agent in an amount of 1 equivalent weight % relative to the equivalent weight of the carboxyl group of the obtained polyurethane resin to neutralize it. Next, 276 parts of ion-exchanged water was added dropwise to this solution at 40° C. over 15 minutes to obtain a milky white transparent dispersion.
The obtained dispersion 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 aqueous resin dispersion thus obtained was subjected to various evaluations, and the results are shown in Table 2.

(Comparative Example 2)
In a four-neck flask equipped with a thermometer, a stirrer, and a reflux condenser, 53 parts of ion-exchanged water, 0.71 parts of Emulsogen EPN 287 (manufactured by CLARIANT, nonionic surfactant), and 1.79 parts of Emulsogen EPA 073 (manufactured by CLARIANT, anionic surfactant) were added, and the mixture was 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, 7.14 parts of Emulsogen EPA 073, and 40 parts of ion-exchanged water were mixed and stirred to obtain an emulsion monomer, and an aqueous initiator solution of 0.5 parts of potassium persulfate and 24.5 parts of ion-exchanged water was prepared. Thereafter, the polymerization reaction was allowed to proceed while the emulsion monomer composition and the aqueous initiator solution were added dropwise over 3 hours and 30 minutes while maintaining the internal temperature at 75° C. After completion of the dropwise addition, 1.85 parts of a 10% aqueous ammonia solution was added, and the mixture was then maintained at 75° C. for 1.5 hours. Thereafter, 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-based 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-based resin were equal in weight, thereby obtaining a mixed aqueous resin dispersion of the polyurethane resin and the (meth)acrylate-based resin.
The aqueous resin dispersion thus obtained was subjected to various evaluations, and the results are shown in Table 2.

Comparative Example 1, in which no (meth)acrylic resin was used, was poor in heat resistance and water resistance.
Comparative Example 2, in which the polyurethane resin and the (meth)acrylic resin were not composited, was poor 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 (11)

A composite resin of polyurethane resin A having a structure derived from linear diol (a1-1) having 8 to 11 carbon atoms and (meth)acrylate resin B. The composite resin according to claim 1, wherein the acid value of the resin A is 15 to 60 mg KOH/g. The composite resin according to claim 1 or 2, which contains 20% by weight or more and 90% by weight or less of the linear diol (a1-1) relative to the total weight of the resin A. The composite resin according to claim 1 or 2, which contains 10 to 90% by weight of resin A based on the total weight of the composite resin. The composite resin according to claim 1 or 2, wherein the resin A has a chemical structure derived from a polycarbonate polyol. The composite resin according to claim 1 or 2, wherein the diol (a1-1) has 10 carbon atoms. The composite resin according to claim 1 or 2, wherein at least one of the polyurethane resin A and the (meth)acrylate resin B is made using a raw material of biological origin. The composite resin according to claim 1 or 2, having a biomass ratio of 20% or more. An aqueous resin dispersion containing the composite resin according to claim 1 or 2. A coating composition containing the composite resin according to claim 1 or 2. An aqueous coating material containing the composite resin described in claim 1 or 2.