Acrylic urethane composite resin particle aqueous dispersion, aqueous paint composition, coating film formation method, and multi-layer coating film formation method

Abstract

To provide an acrylic urethane composite resin particle water dispersion in which a water based coating composition is excellent in storage stability when being used as a component of the water based coating composition, and by which a coating film excellent in wear resistance, chipping resistance, and glass adhesiveness can be formed even when the water based coating composition is cured at a relatively low temperature.SOLUTION: There is provided an acrylic urethane composite resin particle water dispersion which has: (A) an urethane resin part which is obtained from a component including, (a1) a compound comprising a secondary amino group and an alkoxysilyl group and (a2) an isocyanate group-containing urethane prepolymer; and (B) an acrylic resin part which is obtained from a component including, (b) compound which has a polymerizable unsaturated group and has no hydroxy group or has one hydroxy group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an acrylic urethane composite resin particle aqueous dispersion, an aqueous paint composition, a coating film forming method, and a multi-layer coating film forming method.

Background Art

[0002] In automotive painting, after applying an electrodeposition paint to an object to be painted, a multi-layer coating film is formed by a three-coat two-bake (3C2B) method in which intermediate coating is applied → baked and cured → water-based base paint is applied → preheated → clear coat is applied → baked and cured. However, in recent years, from the perspective of energy conservation, the baking and curing process after applying the intermediate coating is omitted, and after applying an electrodeposition paint to the object to be painted, water-based intermediate coating is applied → preheated if necessary → water-based base paint is applied → preheated → clear coat is applied → baked and cured, and a three-coat one-bake (3C1B) method is becoming widespread.

[0003] Recently, in order to further reduce the energy used, it has been required to lower the heating temperature in the above baking and curing process.

[0004] However, when the heating temperature is low, the chipping resistance against the chipping phenomenon in which the coating film peels off due to the impact of small stones on the painted surface of the outer panel of the automobile body, and the glass adhesion, which is the resistance against the load applied to the adhesion part between the glass and the coating film, may be insufficient.

[0005] In addition, as a painted part of an automobile body, in a part where the requirement for appearance is not high, consideration is being given to further reducing the painting man-hours. For example, after applying an electrodeposition paint to an object to be painted, a one-coat one-bake (1C1B) method in which water-based base paint is applied → preheated → baked and cured is being considered. In this case, since the topmost coating film is a base coating film formed by a water-based base paint, high coating film performance such as abrasion resistance is required for the base coating film.

[0006] However, paint compositions that exhibit high coating performance even at relatively low heating temperatures generally tend to be highly reactive and may have insufficient storage stability.

[0007] Patent Document 1 describes an aqueous paint composition comprising (A) an aqueous resin, (B) a melamine resin, and (C) a weak acid catalyst, wherein the (A) aqueous resin has a hydroxyl value of 80 to 200 mg KOH / g in terms of resin solids, the (B) melamine resin has an average imino group of 1.0 or more and an average methylol group of 0.5 or more per melamine nucleus, the mass ratio of the (A) aqueous resin to the (B) melamine resin is 90 / 10 to 60 / 40 in terms of solids, and the content of the (C) weak acid catalyst is 0.1 to 10.0 parts by mass when the combined (A) aqueous resin and (B) melamine resin are 100 parts by mass, and this aqueous paint composition exhibits superior low-temperature curing properties and superior storage stability compared to conventional paints. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2015-174958 [Overview of the project] [Problems that the invention aims to solve]

[0009] In the technology described in Patent Document 1, although the resulting aqueous coating composition exhibits excellent low-temperature curing properties and storage stability, the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film were sometimes insufficient.

[0010] The object of the present invention is to provide an acrylic urethane composite resin particle aqueous dispersion that, when used as a component of an aqueous coating composition, enables the aqueous coating composition to exhibit excellent storage stability and, even when cured at relatively low temperatures, can form a coating film with excellent abrasion resistance, chipping resistance, and glass adhesion. [Means for solving the problem]

[0011] The present inventors, after diligent research to achieve the above objective, have found that the above objective can be achieved by an acrylic urethane composite resin particle aqueous dispersion comprising: a urethane resin portion (A) obtained from a component comprising a compound (a1) having a secondary amino group and an alkoxysilyl group, and an isocyanate group-containing urethane prepolymer (a2); and an acrylic resin portion (B) obtained from a component comprising a compound (b) having a polymerizable unsaturated group and having no hydroxyl group or one hydroxyl group, wherein the compound (a1) having a secondary amino group and an alkoxysilyl group is obtained from a component comprising a compound (a11) containing a primary amino group and an alkoxysilyl group, and a polymerizable unsaturated group-containing compound (a12); and the isocyanate group-containing urethane prepolymer (a2) is obtained from a component comprising a polyisocyanate component (a21) and a polyol component (a22).

[0012] In other words, the present invention is as follows: <1> ~ <13> This concerns... <1> (A)(a1) A compound having a secondary amino group and an alkoxysilyl group, and (a2) A urethane resin portion obtained from a component comprising an isocyanate group-containing urethane prepolymer, (B)(b) An acrylic resin portion obtained from a component containing a polymerizable unsaturated group and a compound that does not have a hydroxyl group or has one hydroxyl group, comprising an aqueous dispersion of acrylic urethane composite resin particles, The (a1) compound having a secondary amino group and an alkoxysilyl group is obtained from a component comprising (a11) a compound containing a primary amino group and an alkoxysilyl group and (a12) a polymerizable unsaturated group-containing compound, and the (a2) isocyanate group-containing urethane prepolymer is obtained from a component comprising (a21) a polyisocyanate component and (a22) a polyol component, in an aqueous dispersion of acrylic urethane composite resin particles. <2> The compound (a11) containing the primary amino group and the alkoxysilyl group comprises the compound (a11-1) containing the primary amino group, the secondary amino group and the alkoxysilyl group. <1> Aqueous dispersion of acrylic urethane composite resin particles as described above. <3> The polymerizable unsaturated group-containing compound (a12) includes (meth)acrylate, <1> or <2> Aqueous dispersion of acrylic urethane composite resin particles as described above. <4> The polyisocyanate component (a21) contains an alicyclic polyisocyanate compound (a21-1), <1> ~ <3> An aqueous dispersion of acrylic urethane composite resin particles as described in any one of the following. <5> The polyol component (a22) comprises at least one selected from polycarbonate polyol (a22-1) and polyether polyol (a22-2). <1> ~ <4> An aqueous dispersion of acrylic urethane composite resin particles as described in any one of the following. <6> The core-shell structure consists of a shell made of the urethane resin portion (A) and a core made of the acrylic resin portion (B). <1> ~ <5> An aqueous dispersion of acrylic urethane composite resin particles as described in any one of the following. <7> <1> ~ <6> A water-based paint composition containing an aqueous dispersion of acrylic urethane composite resin (AB) particles as described in any one of the above. <8> The aqueous dispersion of acrylic urethane composite resin (AB) particles is contained in an amount ranging from 10 to 70 parts by mass, based on 100 parts by mass of the total resin solids in the aqueous paint composition. <7> The aqueous paint composition described above. <9> Furthermore, it contains at least one resin selected from acrylic resin (C) and polyester resin (D). <7> or <8> The aqueous paint composition described above. <10> Furthermore, it contains a hardening agent (E), <7> ~ <9> A water-based paint composition as described in any one of the following. <11> Step (I-1): On the object to be coated, <7> ~ <10> A step of applying an aqueous paint composition described in any one of the above to form an uncured colored paint film, A method for forming a coating film, comprising: step (I-2): a step of heat-curing the uncured colored coating film formed in step (I-1). <12> Step (II-1): On the object to be coated, <7> ~ <10> A step of applying an aqueous paint composition described in any one of the following to form an uncured intermediate coating film, Step (II-2): A step of applying a base coat paint composition onto the uncured intermediate coating film formed in step (II-1) to form an uncured base coat film. Step (II-3): A step of applying a clear coat paint composition onto the uncured base coat film formed in step (II-2) to form an uncured clear coat film. A method for forming a multi-layer coating, comprising: step (II-4): a step of simultaneously heating and curing the uncured intermediate coating film formed in step (II-1), the uncured base coat coating film formed in step (II-2), and the uncured clear coat coating film formed in step (II-3). <13> Step (IV-1): On the object to be coated, <7> ~ <10> A step of applying an aqueous paint composition described in any one of the following to form an uncured intermediate coating film, Step (IV-2): On the uncured intermediate coating film formed in step (IV-1), <7> ~ <10> A step of applying an aqueous paint composition described in any one of the above to form an uncured base coat film, Step (IV-3): A step of applying a clear coat paint composition onto the uncured base coat film formed in step (IV-2) to form an uncured clear coat film. A method for forming a multilayer coating, comprising: step (IV-4): a step of simultaneously heating and curing the uncured intermediate coating film formed in step (IV-1), the uncured base coat coating film formed in step (IV-2), and the uncured clear coat coating film formed in step (IV-3). [Effects of the Invention]

[0013] According to the acrylic urethane composite resin particle aqueous dispersion of the present invention, when used as a component of an aqueous coating composition, the aqueous coating composition exhibits excellent storage stability, and even when the aqueous coating composition is cured at a relatively low temperature, it can form a coating film with excellent abrasion resistance, chipping resistance, and glass adhesion.

Mode for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described in detail. These are examples of desirable embodiments, and the present invention is not limited to these contents.

[0015] [Acrylic Urethane Composite Resin (AB) Particle Aqueous Dispersion] The acrylic urethane composite resin (AB) particle aqueous dispersion of the present invention is obtained from a constituent component containing a compound (a1) having a secondary amino group and an alkoxysilyl group, and an isocyanate group-containing urethane prepolymer (a2), a urethane resin part (A), and an acrylic resin part (B) obtained from a constituent component containing a compound (b) having a polymerizable unsaturated group and having no hydroxyl group or having one hydroxyl group, an acrylic urethane composite resin particle aqueous dispersion, wherein the compound (a1) having a secondary amino group and an alkoxysilyl group is obtained from a constituent component containing a compound (a11) having a primary amino group and an alkoxysilyl group and a polymerizable unsaturated group-containing compound (a12), and the isocyanate group-containing urethane prepolymer (a2) is obtained from a constituent component containing a polyisocyanate component (a21) and a polyol component (a22).

[0016] The acrylic urethane composite resin (AB) particle aqueous dispersion can be produced by a conventionally known method for producing an acrylic urethane composite resin. Among them, from the viewpoint of production stability and the like, it is preferably produced by the following method (comprising the following production steps 1 to 5).

[0017] Production Step 1. First, a compound (a1) having a secondary amino group and an alkoxysilyl group is synthesized by reacting a compound (a11) containing a primary amino group and an alkoxysilyl group with a polymerizable unsaturated group-containing compound (a12).

[0018] Manufacturing process 2. Next, an isocyanate group-containing urethane prepolymer (a2) is synthesized in the presence of a compound (b) having a polymerizable unsaturated group and having no hydroxyl group or having one hydroxyl group, which is a constituent component of the acrylic resin part (B).

[0019] Manufacturing process 3. Next, a compound (a1) having a secondary amino group and an alkoxysilyl group obtained in manufacturing process 1 is added to a mixture containing the isocyanate group-containing urethane prepolymer (a2) obtained in manufacturing process 2 and the compound (b) having a polymerizable unsaturated group and having no hydroxyl group or having one hydroxyl group, and the isocyanate group-containing urethane prepolymer (a2) and the compound (a1) having a secondary amino group and an alkoxysilyl group are reacted to obtain a urethane resin part (A).

[0020] Manufacturing process 4. Next, deionized water is added and emulsified to obtain an aqueous dispersion. If necessary, a chain extension reaction and solvent removal are further carried out.

[0021] Manufacturing process 5. Next, a polymerization initiator is added to the above aqueous dispersion and a polymerization reaction is carried out to obtain an aqueous dispersion of acrylic urethane composite resin (AB) particles containing a urethane resin part (A) and an acrylic resin part (B).

[0022] Manufacturing process 1 First, a compound (a1) having a secondary amino group and an alkoxysilyl group is synthesized by reacting a compound (a11) containing a primary amino group and an alkoxysilyl group with a polymerizable unsaturated group-containing compound (a12).

[0023] Examples of the compound (a11) containing a primary amino group and an alkoxysilyl group include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and the like.

[0024] These compounds (a11) containing primary amino groups and alkoxysilyl groups can be used individually or in combination of two or more.

[0025] As the compound (a11) containing the above-mentioned primary amino group and alkoxysilyl group, commercially available products can be used. Examples of commercially available product names include "KBM-903", "KBE-903", "KBM-602", "KBM-603" (all manufactured by Shin-Etsu Chemical Co., Ltd., product names), "Dynasylan AMEO", "Dynasylan AMMO", "Dynasylan DAMO", "Dynasylan DAMO-T" (all manufactured by Evonik, product names), "DOWSIL Z-6610 Silane", "DOWSIL Z-6611 Silane", "DOWSIL Z-6094 Silane", "XIAMETER OFS-6020 Silane" (all manufactured by Dow-Toray, product names), "A-1100", "A-1110", "A-1120", "A-2120" (all manufactured by Momentive, product names), etc.

[0026] The compound (a11) containing the primary amino group and alkoxysilyl group described above preferably includes a compound (a11-1) containing a primary amino group, a secondary amino group, and an alkoxysilyl group, from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance and glass adhesion of the formed coating film.

[0027] Examples of compounds (a11-1) containing the above-mentioned primary amino group, secondary amino group, and alkoxysilyl group include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

[0028] As the compound (a11-1) containing the primary amino group, secondary amino group, and alkoxysilyl group mentioned above, commercially available products can be used. Examples of commercially available product names include "KBM-602", "KBM-603" (both manufactured by Shin-Etsu Chemical Co., Ltd., product names), "Dynasylan DAMO", "Dynasylan DAMO-T" (both manufactured by Evonik, product names), "DOWSIL Z-6094 Silane", "XIAMETER OFS-6020 Silane" (both manufactured by Dow-Toray Industries, Ltd., product names), "A-1120", "A-2120" (both manufactured by Momentive, product names), etc.

[0029] When the compound (a11) containing the primary amino group and alkoxysilyl group includes a compound (a11-1) containing a primary amino group, a secondary amino group and an alkoxysilyl group, the content of the compound (a11-1) containing the primary amino group, a secondary amino group and an alkoxysilyl group is preferably in the range of 20 to 100% by mass, more preferably in the range of 50 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the compound (a11) containing the primary amino group and alkoxysilyl group, from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0030] The polymerizable unsaturated group is an unsaturated group that can undergo radical polymerization, and specifically, examples include acryloyl group, methacryloyl group, vinyl group, allyl group, propenyl group, isopropenyl group, maleimide group, vinyl ether group, and the like. Of these polymerizable unsaturated groups, acryloyl group and methacryloyl group are preferred from the viewpoint of excellent reactivity, and acryloyl group is particularly preferred.

[0031] Furthermore, in this specification, "(meth)acrylate" means "acrylate or methacrylate." "(meth)acrylic acid" means "acrylic acid or methacrylic acid." Also, "(meth)acryloyl" means "acryloyl or methacryloyl." Also, "(meth)acrylamide" means "acrylamide or methacrylamide."

[0032] Examples of the polymerizable unsaturated group-containing compound (a12) include monoesters of (meth)acrylic acid and dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone modified forms of the monoesters; N-hydroxymethyl (meth)acrylamide; allyl alcohol; and (meth)acrylate having polyoxyethylene chains with hydroxyl groups at the molecular ends. Hydroxyl group-containing polymerizable unsaturated monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate. )Acrylates, "Isostearyl Acrylate" (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and other alkyl or cycloalkyl (meth)acrylates; polymerizable unsaturated monomers having an isobornyl group, such as isobornyl (meth)acrylate; polymerizable unsaturated monomers having an adamantyl group, such as adamantyl (meth)acrylate. Saturated monomers; polymerizable unsaturated monomers having a tricyclodecenyl group, such as tricyclodecenyl (meth)acrylate; polymerizable unsaturated monomers containing aromatic rings, such as benzyl (meth)acrylate, styrene, α-methylstyrene, and vinyltoluene; polymerizable unsaturated monomers having an alkoxysilyl group, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, and γ-(meth)acryloyloxypropyltriethoxysilane;Perfluoroalkyl (meth)acrylates such as perfluorobutylethyl (meth)acrylate and perfluorooctylethyl (meth)acrylate; polymerizable unsaturated monomers having fluorinated alkyl groups such as fluoroolefins; polymerizable unsaturated monomers having photopolymerizable functional groups such as maleimide groups; vinyl compounds such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, and vinyl acetate; polymerizable unsaturated monomers containing carboxyl groups such as (meth)acrylic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate; (meth)acrylonitrile, (meth)acrylamide, and N,N-dimethylaminoethyl (meth)acrylic acid Nitrogen-containing polymerizable unsaturated monomers such as phosphates, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, and adducts of glycidyl (meth)acrylate with amines; epoxy-group-containing polymerizable unsaturated monomers such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, and allyl glycidyl ether; (meth)acrylates having polyoxyethylene chains with alkoxy groups at the molecular ends;Glycerol di(meth)acrylate, 1,1,1-trishydroxymethylethane di(meth)acrylate, allyl(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanedi Examples include all-di(meth)acrylate, pentaerythritol tetra(meth)acrylate, 1,1,1-trishydroxymethylethane tri(meth)acrylate, 1,1,1-trishydroxymethylpropane tri(meth)acrylate, methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, triallyl isocyanurate, diallyl terephthalate, divinylbenzene, polyethylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, etc.

[0033] These polymerizable unsaturated group-containing compounds (a12) can be used individually or in combination of two or more.

[0034] The polymerizable unsaturated group-containing compound (a12) described above preferably contains (meth)acrylate, more preferably alkyl or cycloalkyl (meth)acrylate, even more preferably alkyl (meth)acrylate having an alkyl group having 2 to 6 carbon atoms, and particularly preferably alkyl (meth)acrylate having an alkyl group having 3 to 6 carbon atoms.

[0035] Examples of the above (meth)acrylates include monoesters of (meth)acrylic acid and dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone modified forms of the monoesters; (meth)acrylates having polyoxyethylene chains with hydroxyl groups at the molecular ends; methyl (meth)acrylate; ethyl (meth)acrylate; n-propyl ( Meth)acrylate, i-propyl(meth)acrylate, n-butyl(meth)acrylate, i-butyl(meth)acrylate, tert-butyl(meth)acrylate, n-hexyl(meth)acrylate, n-octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, nonyl(meth)acrylate, tridecyl(meth)acrylate, lauryl(meth)acrylate, stearyl(meth)acrylate, "isostearyl acrylate" (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclohexyl(meth)acrylate Lilate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecenyl (meth)acrylate, benzyl (meth)acrylate, perfluorobutylethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, β-carboxyethyl acrylate, N,N-dimethylaminoethyl (meth)acrylate )Acrylates, N,N-diethylaminoethyl (meth)acrylate, nitrogen-containing polymerizable unsaturated monomers such as adducts of glycidyl (meth)acrylate with amines, glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, (meth)acrylate having polyoxyethylene chains with alkoxy groups at the molecular ends;Examples include glycerol di(meth)acrylate, 1,1,1-trishydroxymethylethane di(meth)acrylate, allyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, 1,1,1-trishydroxymethylethane tri(meth)acrylate, 1,1,1-trishydroxymethylpropane tri(meth)acrylate, polyethylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, etc.

[0036] When the polymerizable unsaturated group-containing compound (a12) includes (meth)acrylate, the content of (meth)acrylate is preferably in the range of 20 to 100% by mass, more preferably in the range of 50 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the polymerizable unsaturated group-containing compound (a12), from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance and glass adhesion of the formed coating film.

[0037] Examples of the alkyl or cycloalkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, "isostearyl acrylate" (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and the like.

[0038] When the polymerizable unsaturated group-containing compound (a12) includes an alkyl or cycloalkyl (meth)acrylate, the content of the alkyl or cycloalkyl (meth)acrylate is preferably in the range of 20 to 100% by mass, more preferably in the range of 50 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the polymerizable unsaturated group-containing compound (a12), from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance and glass adhesion of the formed coating film.

[0039] Examples of alkyl(meth)acrylates having an alkyl group with 2 to 6 carbon atoms include ethyl(meth)acrylate, n-propyl(meth)acrylate, i-propyl(meth)acrylate, n-butyl(meth)acrylate, i-butyl(meth)acrylate, tert-butyl(meth)acrylate, n-hexyl(meth)acrylate, and the like.

[0040] When the polymerizable unsaturated group-containing compound (a12) includes an alkyl (meth)acrylate having an alkyl group having 2 to 6 carbon atoms, the content of the alkyl (meth)acrylate having an alkyl group having 2 to 6 carbon atoms is preferably in the range of 20 to 100% by mass, more preferably in the range of 50 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the polymerizable unsaturated group-containing compound (a12), from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance and glass adhesion of the formed coating film.

[0041] Examples of alkyl(meth)acrylates having an alkyl group with 3 to 6 carbon atoms include n-propyl(meth)acrylate, i-propyl(meth)acrylate, n-butyl(meth)acrylate, i-butyl(meth)acrylate, tert-butyl(meth)acrylate, and n-hexyl(meth)acrylate.

[0042] When the polymerizable unsaturated group-containing compound (a12) includes an alkyl (meth)acrylate having an alkyl group having 3 to 6 carbon atoms, the content of the alkyl (meth)acrylate having an alkyl group having 3 to 6 carbon atoms is preferably in the range of 20 to 100% by mass, more preferably in the range of 50 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the polymerizable unsaturated group-containing compound (a12), from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance and glass adhesion of the formed coating film.

[0043] The synthesis of the compound (a1) having the secondary amino group and the alkoxysilyl group is preferably carried out at a temperature in the range of 30 to 100°C.

[0044] In the synthesis of the compound (a1) having the secondary amino group and alkoxysilyl group described above, any organic solvent that does not interfere with the reaction between the compound (a11) containing the primary amino group and alkoxysilyl group and the polymerizable unsaturated group-containing compound (a12) can be used. Examples of such organic solvents include aromatic hydrocarbon solvents such as toluene and xylene, alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane, and ester solvents such as ethyl acetate and butyl acetate. Among these, alicyclic hydrocarbon solvents and ester solvents can be preferably used.

[0045] These organic solvents can be used individually or in combination of two or more.

[0046] Additionally, antioxidants can be added as needed.

[0047] Examples of the above-mentioned antioxidants include dibutylhydroxytoluene, hydroquinone, methylhydroquinone, and t-butylhydroquinone.

[0048] The mass ratio (a11) / (a12) of the compound (a11) containing a primary amino group and an alkoxysilyl group and the polymerizable unsaturated group-containing compound (a12) in the compound (a1) having a secondary amino group and an alkoxysilyl group is preferably in the range of 25 / 75 to 60 / 40, more preferably in the range of 35 / 65 to 55 / 45, and even more preferably in the range of 40 / 60 to 50 / 50, from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0049] Manufacturing process 2 Next, an isocyanate group-containing urethane prepolymer (a2) is synthesized in the presence of a compound (b) which is a component of the acrylic resin portion (B) and has polymerizable unsaturated groups but does not have hydroxyl groups or has one hydroxyl group.

[0050] Examples of the polymerizable unsaturated group having no hydroxyl group or having one hydroxyl group (b) include a polymerizable unsaturated group having one hydroxyl group (b1) and a polymerizable unsaturated group having no hydroxyl group (b2).

[0051] Examples of the compound (b1) having the above polymerizable unsaturated group and one hydroxyl group include a compound (b1-1) having one polymerizable unsaturated group and one hydroxyl group, and a compound (b1-2) having two or more polymerizable unsaturated groups and one hydroxyl group.

[0052] Examples of the compound (b1-1) having one polymerizable unsaturated group and one hydroxyl group include monoesters of (meth)acrylic acid and dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone modified forms of the monoesters; N-hydroxymethyl (meth)acrylamide; allyl alcohol; and hydroxyl group-containing polymerizable unsaturated monomers such as (meth)acrylates having polyoxyethylene chains with hydroxyl groups at the molecular termini.

[0053] These compounds (b1-1), each having one polymerizable unsaturated group and one hydroxyl group, can be used individually or in combination of two or more.

[0054] Examples of the compounds (b1-2) having two or more polymerizable unsaturated groups and one hydroxyl group include glycerol di(meth)acrylate and 1,1,1-trishydroxymethylethane di(meth)acrylate.

[0055] These compounds (b1-2), which have two or more polymerizable unsaturated groups and one hydroxyl group, can be used individually or in combination of two or more.

[0056] If the compound (b) having a polymerizable unsaturated group and having neither a hydroxyl group nor one hydroxyl group includes a compound (b1) having a polymerizable unsaturated group and one hydroxyl group, the content of the compound (b1) having a polymerizable unsaturated group and one hydroxyl group is preferably in the range of 1 to 50% by mass, more preferably in the range of 2 to 40% by mass, and even more preferably in the range of 5 to 30% by mass, based on the total solid content of the compound (b) having a polymerizable unsaturated group and having neither a hydroxyl group nor one hydroxyl group, from the viewpoint of manufacturing stability, etc.

[0057] Examples of the polymerizable unsaturated compound (b2) having a polymerizable unsaturated group but lacking a hydroxyl group include a compound having one polymerizable unsaturated group but lacking a hydroxyl group (b2-1), and a compound having two or more polymerizable unsaturated groups but lacking a hydroxyl group (b2-2).

[0058] Examples of the compound (b2-1) having one polymerizable unsaturated group and lacking a hydroxyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, and lauryl (meth)acrylate. ) Acrylate, stearyl (meth)acrylate, "isostearyl acrylate" (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), alkyl or cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate; polymerizable unsaturated monomers having an isobornyl group such as isobornyl (meth)acrylate; adamantyl group such as adamantyl (meth)acrylate Polymerizable unsaturated monomers containing a tricyclodecenyl group; polymerizable unsaturated monomers having a tricyclodecenyl group, such as tricyclodecenyl (meth)acrylate; polymerizable unsaturated monomers containing an aromatic ring, such as benzyl (meth)acrylate, styrene, α-methylstyrene, and vinyltoluene; polymerizable unsaturated monomers having an alkoxysilyl group, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, and γ-(meth)acryloyloxypropyltriethoxysilane; Perfluoroalkyl (meth)acrylates such as perfluorobutylethyl (meth)acrylate and perfluorooctylethyl (meth)acrylate; polymerizable unsaturated monomers having fluorinated alkyl groups such as fluoroolefins; polymerizable unsaturated monomers having photopolymerizable functional groups such as maleimide groups; vinyl compounds such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, and vinyl acetate; polymerizable unsaturated monomers containing carboxyl groups such as (meth)acrylic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate;Examples include nitrogen-containing polymerizable unsaturated monomers such as (meth)acrylonitrile, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, and adducts of glycidyl (meth)acrylate with amines; epoxy-group-containing polymerizable unsaturated monomers such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, and allyl glycidyl ether; and (meth)acrylates having polyoxyethylene chains with alkoxy groups at the molecular ends.

[0059] These compounds (b2-1), which have one polymerizable unsaturated group and no hydroxyl group, can be used individually or in combination of two or more.

[0060] Examples of the compounds (b2-2) having two or more polymerizable unsaturated groups and lacking hydroxyl groups include allyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and 1,6-hexanediol. Examples include di(meth)acrylate, pentaerythritol tetra(meth)acrylate, 1,1,1-trishydroxymethylethane tri(meth)acrylate, 1,1,1-trishydroxymethylpropane tri(meth)acrylate, methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, triallyl isocyanurate, diallyl terephthalate, divinylbenzene, polyethylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and the like.

[0061] These compounds (b2-2), which have two or more polymerizable unsaturated groups and no hydroxyl groups, can be used individually or in combination of two or more.

[0062] As for the compound (b2) having polymerizable unsaturated groups and lacking hydroxyl groups, it is preferable that it includes a compound (b2-2) having two or more polymerizable unsaturated groups and lacking hydroxyl groups, from the viewpoint of storage stability of the resulting aqueous coating composition.

[0063] The compound (b2-2) having two or more polymerizable unsaturated groups and lacking hydroxyl groups has the function of imparting a crosslinked structure to the copolymer.

[0064] When the compound (b2) having polymerizable unsaturated groups and lacking hydroxyl groups includes the compound (b2-2) having two or more polymerizable unsaturated groups and lacking hydroxyl groups, the content of the compound (b2-2) having two or more polymerizable unsaturated groups and lacking hydroxyl groups is preferably in the range of 0.5 to 50% by mass, more preferably in the range of 1.0 to 40% by mass, and even more preferably in the range of 2.0 to 20% by mass, based on the total solid content of the compound (b2) having polymerizable unsaturated groups and lacking hydroxyl groups, from the viewpoint of chipping resistance and glass adhesion of the formed coating film.

[0065] If the compound (b) having a polymerizable unsaturated group and lacking a hydroxyl group or having one hydroxyl group includes a compound (b2) having a polymerizable unsaturated group and lacking a hydroxyl group, the content of the compound (b2) having a polymerizable unsaturated group and lacking a hydroxyl group is preferably in the range of 50 to 99% by mass, more preferably in the range of 60 to 97% by mass, and even more preferably in the range of 70 to 95% by mass, based on the total solid content of the compound (b) having a polymerizable unsaturated group and lacking a hydroxyl group or having one hydroxyl group, from the viewpoint of manufacturing stability, etc.

[0066] Synthesis of isocyanate group-containing urethane prepolymer (a2) The isocyanate group-containing urethane prepolymer (a2) can be obtained from components comprising a polyisocyanate component (a21), a polyol component (a22), and, if necessary, a compound that further contains both an active hydrogen group and an ion-forming group as a water-dispersing group-contributing component.

[0067] Polyisocyanate component (a21) Examples of the polyisocyanate component (a21) include alicyclic polyisocyanates (a21-1), aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of said polyisocyanates.

[0068] As the polyisocyanate component (a21) mentioned above, it is preferable to include alicyclic polyisocyanate (a21-1) from the viewpoint of glass adhesion of the formed coating film.

[0069] Examples of the above alicyclic polyisocyanates (a21-1) include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), and 2-methyl-1,3-cyclohexylene Alicyclic diisocyanates such as diisocyanates, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or mixtures thereof, methylenebis(4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl 2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 6-(2- Examples include alicyclic triisocyanates such as socyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, and 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane.

[0070] If the polyisocyanate component (a21) contains the alicyclic polyisocyanate (a21-1), the content of the alicyclic polyisocyanate (a21-1) is preferably in the range of 50 to 100% by mass, more preferably in the range of 70 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the polyisocyanate component (a21), from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0071] Examples of the aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4 or 2,2,4-trimethylhexamethylene diisocyanate, dimer diisocyanate, and 2,6-methyl diisocyanatohexanoate (common name: lysine). Examples include aliphatic diisocyanates such as diisocyanates; and aliphatic triisocyanates such as 2-isocyanatoethyl 2,6-diisocyanatohexanoate, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane.

[0072] Examples of the aforementioned aromatic aliphatic polyisocyanates include aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; and aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.

[0073] Examples of the aromatic polyisocyanates include aromatic diisocyanates such as m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, 2,4-tolylenediisocyanate (common name: 2,4-TDI) or 2,6-tolylenediisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidinediisocyanate, and 4,4'-diphenyletherdiisocyanate; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; and aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate.

[0074] Furthermore, examples of derivatives of the polyisocyanate include dimers, trimers, biuret, allophanate, uretodione, uretoimine, isocyanurate, oxadiazinetrione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI), crude TDI, and the like.

[0075] The above-mentioned polyisocyanates and their derivatives may be used individually or in combination of two or more.

[0076] The above-mentioned polyisocyanates may also be used in the form of blocked isocyanates, which are blocked by a blocking agent.

[0077] Examples of the above-mentioned blocking agents include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, and lauryl alcohol; ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylolmelamine, diacetone alcohol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate. Alcohol-based compounds such as droxyethyl methacrylate; oxime-based compounds such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; active methylene-based compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, and methylthiophenone. Mercaptan-based compounds such as ethylthiophenol; acid amide-based compounds such as acetanilide, acetanisidide, acetotoluid, acrylamide, methacrylamide, acetic acid amide, stearic acid amide, and benzamide; imide-based compounds such as succinimide, phthalimide, and maleimide; amine-based compounds such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine; imidazole-based compounds such as imidazole and 2-ethylimidazole;Examples of azole compounds include urea-based compounds such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea; carbamic acid ester compounds such as phenyl N-phenylcarbamate; imine-based compounds such as ethyleneimine and propyleneimine; sulfite-based compounds such as sodium bisulfite and potassium bisulfite; and azole compounds. Examples of the above-mentioned azole compounds include pyrazoles or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; imidazoles or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenylimidazole; and imidazoline derivatives such as 2-methylimidazoline and 2-phenylimidazoline.

[0078] The above blocking process (reacting with the blocking agent) can be carried out by adding a solvent as needed. Suitable solvents for the blocking reaction are those that are not reactive with isocyanate groups. Examples include acetone, ketones such as methyl ethyl ketone, esters such as ethyl acetate, and solvents such as N-methyl-2-pyrrolidone (NMP).

[0079] Polyol component (a22) The polyol component (a22) is a compound having at least two hydroxyl groups in one molecule.

[0080] The polyol component (a22) described above preferably contains at least one selected from polycarbonate polyol (a22-1) and polyether polyol (a22-2), and more preferably contains both polycarbonate polyol (a22-1) and polyether polyol (a22-2), from the viewpoint of storage stability of the resulting aqueous coating composition and the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0081] The above polycarbonate polyol (a22-1) is a compound obtained by polycondensation reaction of a known polyol component with a carbonylating agent using a conventional method. Examples of polyol components include diol components and polyhydric alcohol components such as trihydric or higher alcohols.

[0082] The above diol components include linear diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol and 1,10-decanediol; 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-ethyl-1,6-hexanediol, 2,2-diethyl-1,3-propanediol, and 2-butyl-2-ethyl-1,3- Examples include branched diols such as propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, and 2-ethyl-1,3-hexanediol; alicyclic diols such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; aromatic diols such as p-xylenediol and p-tetrachloroxylenediol; and ether diols such as diethylene glycol and dipropylene glycol. These diol components can be used individually or in combination of two or more.

[0083] Examples of trivalent or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, trimethylolpropane dimers, and pentaerythritol. These trivalent or higher alcohols can be used individually or in combination of two or more.

[0084] Known carbonylating agents can be used. Specifically, examples include alkylene carbonates, dialkyl carbonates, diallyl carbonates, phosgene, etc., and one or more of these can be used in combination. Among these, preferred examples include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate, etc.

[0085] The number-average molecular weight of the polycarbonate polyol (a22-1) is preferably in the range of 1000 to 5000, more preferably in the range of 1300 to 4500, and even more preferably in the range of 1500 to 3500, from the viewpoint of the chipping resistance of the formed coating film.

[0086] When the polyol component (a22) contains the polycarbonate polyol (a22-1), the content of the polycarbonate polyol (a22-1) is preferably in the range of 35 to 80% by mass, more preferably in the range of 40 to 70% by mass, and even more preferably in the range of 45 to 60% by mass, based on the total solid content of the polyol component (a22), from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0087] As the polyether polyol (a22-2) mentioned above, alkylene oxide adducts of low molecular weight polyols, ring-opening (co)polymers of alkylene oxides or cyclic ethers (such as tetrahydrofuran), etc., can be used. Specifically, examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, (block or random) copolymers of ethylene glycol-propylene glycol, polyhexamethylene glycol, polyoctamethylene glycol, etc.

[0088] The above-mentioned polyether polyols can be used individually or in combination of two or more types.

[0089] The number-average molecular weight of the polyether polyol (a22-2) is preferably in the range of 500 to 10000, more preferably in the range of 1000 to 5000, and even more preferably in the range of 1600 to 4000, from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0090] If the polyol component (a22) contains the polyether polyol (a22-2), the content of the polyether polyol (a22-2) is preferably in the range of 10 to 85% by mass, more preferably in the range of 15 to 60% by mass, and even more preferably in the range of 20 to 40% by mass, based on the total solid content of the polyol component (a22), from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0091] The above-mentioned polyether polyol (a22-2) preferably contains polytetramethylene ether glycol from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance and chipping resistance of the formed coating film.

[0092] When the above polyether polyol (a22-2) contains polytetramethylene ether glycol, the content of the polytetramethylene ether glycol is preferably in the range of 50 to 100% by mass, more preferably in the range of 70 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the polyether polyol (a22-2), from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance and chipping resistance of the formed coating film.

[0093] Furthermore, the polyol component (a22) may include a compound (a22-3) having two or more hydroxyl groups and one or more polymerizable unsaturated groups.

[0094] The compound (a22-3) having two or more hydroxyl groups and one or more polymerizable unsaturated groups imparts polymerizable unsaturated groups to the side chains of the isocyanate group-containing urethane prepolymer (a2).

[0095] Examples of compounds having two or more hydroxyl groups and one or more polymerizable unsaturated groups (a22-3) include reaction products of a glycidyl group-containing compound and (meth)acrylic acid, and reaction products of a trifunctional or more polyol and (meth)acrylic acid.

[0096] As the compound (a22-3) having two or more hydroxyl groups and one or more polymerizable unsaturated groups, commercially available products can be used. Examples of commercially available product names include "Epoxy Ester 40EM", "Epoxy Ester 70PA", "Epoxy Ester 200PA", "Epoxy Ester 80MFA", "Epoxy Ester 3002M", "Epoxy Ester 3002A", "Epoxy Ester 3000MK", "Epoxy Ester 3000A" (all manufactured by Kyoeisha Chemical Co., Ltd.), "Denacol Acrylate DA-212", "Denacol Acrylate DA-314", "Denacol Acrylate DA-911M", "Denacol Acrylate DA-920", "Denacol Acrylate DA-931" (all manufactured by Nagase ChemteX Corporation), "Bremmer GLM", "Bremmer GLM-EX", "Bremmer GLM-R" (all manufactured by NOF Corporation).

[0097] The compound (a22-3) having two or more hydroxyl groups and one or more polymerizable unsaturated groups is preferably a compound having two or more hydroxyl groups and one polymerizable unsaturated group, and more preferably a compound having two hydroxyl groups and one polymerizable unsaturated group, from the viewpoint of storage stability of the resulting aqueous coating composition and chipping resistance of the formed coating film.

[0098] As the compound having the two hydroxyl groups and one polymerizable unsaturated group described above, commercially available products can be used. Examples of commercially available product names include "Bremmer GLM," "Bremmer GLM-EX," and "Bremmer GLM-R" (all manufactured by NOF Corporation).

[0099] If the polyol component (a22) contains a compound (a22-3) having two or more hydroxyl groups and one or more polymerizable unsaturated groups, the content of the compound (a22-3) having two or more hydroxyl groups and one or more polymerizable unsaturated groups is preferably in the range of 1.0 to 15% by mass, more preferably in the range of 2.0 to 10% by mass, and even more preferably in the range of 3.0 to 8.0% by mass, based on the total solid content of the polyol component (a22), from the viewpoint of the storage stability of the resulting aqueous coating composition and the chipping resistance of the formed coating film.

[0100] The above polyol component (a22) may include polycarbonate polyols (a22-1), polyether polyols (a22-2), and polyol components (a22-4) other than compounds having two or more hydroxyl groups and one or more polymerizable unsaturated groups (a22-3).

[0101] Other polyol components (a22-4) besides polycarbonate polyols (a22-1), polyether polyols (a22-2), and compounds having two or more hydroxyl groups and one or more polymerizable unsaturated groups (a22-3) can be used, for example, as low molecular weight polyols, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexane glycol, 2,5-hexanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, tricyclodecanedimethanol, 1,4-cyclohexanedimethanol, etc. These low molecular weight polyols can be used individually or in combination of two or more.

[0102] Furthermore, as polyol components other than the polycarbonate polyol (a22-1), polyether polyol (a22-2), and compounds having two or more hydroxyl groups and one or more polymerizable unsaturated groups (a22-3) (a22-4), high molecular weight polyols such as polyester polyols and polyether ester polyols can be used. These high molecular weight polyols can be used individually or in combination of two or more.

[0103] Examples of the polyester polyols mentioned above include those obtained by polycondensing a dicarboxylic acid (anhydride) such as adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, and phthalic acid with the low molecular weight polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octamethylenediol, and neopentyl glycol under conditions of excess hydroxyl groups. Specifically, examples include ethylene glycol-adipic acid condensate, butanediol-adipic acid condensate, hexamethylene glycol-adipic acid condensate, ethylene glycol-propylene glycol-adipic acid condensate, and polylactone polyols obtained by ring-opening polymerization of lactones using glycol as an initiator. These polyester polyols can be used individually or in combination of two or more.

[0104] Examples of the polyether ester polyol include ether group-containing polyols (such as the polyether polyol (a22-2) or diethylene glycol) or mixtures thereof with other glycols, which are obtained by reacting them with an alkylene oxide in addition to a (anhydrous) dicarboxylic acid as exemplified in the polyester polyols above, such as polytetramethylene glycol-adipic acid condensate. These polyether ester polyols can be used individually or in combination of two or more.

[0105] Compounds that possess both active hydrogen groups and ion-forming groups. Examples of compounds that possess both active hydrogen groups and ion-forming groups include compounds having two or more hydroxyl groups and one or more carboxyl groups in one molecule, compounds having two or more hydroxyl groups and one or more sulfonic acid groups in one molecule, and compounds having two or more amino groups and one or more carboxyl groups in one molecule. These can be used individually or in combination of two or more.

[0106] In particular, as compounds having both the active hydrogen group and the ion-forming group, compounds having two or more hydroxyl groups and one or more carboxyl groups in one molecule, and compounds having two or more hydroxyl groups and one or more sulfonic acid groups in one molecule can be suitably used.

[0107] In the present invention, compounds having two or more hydroxyl groups and ion-forming groups, such as compounds having two or more hydroxyl groups and one or more carboxyl groups in one molecule, and compounds having two or more hydroxyl groups and one or more sulfonic acid groups in one molecule, are included in the polyol component (a22).

[0108] Examples of compounds having two or more hydroxyl groups and one or more carboxyl groups in a single molecule include alkanol carboxylic acid compounds such as dimethylolpropionic acid, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolheptanoic acid, dimethylolnonanoic acid, 1-carboxy-1,5-pentylenediamine, dihydroxybenzoic acid, and 3,5-diaminobenzoic acid, as well as half-ester compounds of polyoxypropylene triol with maleic anhydride and / or phthalic anhydride.

[0109] Examples of compounds having two or more hydroxyl groups and one or more sulfonic acid groups in a single molecule include 2-sulfonic acid-1,4-butanediol, 5-sulfonic acid-di-β-hydroxyethyl isophthalate, and N,N-bis(2-hydroxyethyl)aminoethylsulfonic acid.

[0110] As for the compound having both the active hydrogen group and the ion-forming group, it is preferable to use a compound having two or more hydroxyl groups and one or more carboxyl groups in one molecule, from the viewpoint of the flexibility of the coating film formed.

[0111] When the polyol component (a22) contains a compound having two or more hydroxyl groups and one or more carboxyl groups, its content is preferably in the range of 1 to 30% by mass, more preferably in the range of 1 to 25% by mass, and even more preferably in the range of 1 to 20% by mass, relative to the total amount of compounds constituting the polyol component (a22), from the viewpoint of the storage stability of the resulting aqueous coating composition.

[0112] The method for producing the isocyanate group-containing urethane prepolymer (a2) is not particularly limited, and conventionally known methods can be applied. For example, the production method involves urethane-forming a polyisocyanate component (a21) and a polyol component (a22) in an organic solvent, or, if necessary, adding a compound having both active hydrogen groups and ion-forming groups and proceeding with the urethane-forming reaction to synthesize the product.

[0113] From the viewpoint of the storage stability of the resulting aqueous coating composition, the isocyanate group-containing urethane prepolymer (a2) preferably contains a compound having both an active hydrogen group and an ion-forming group.

[0114] Additionally, polymerization inhibitors can be added as needed.

[0115] A catalyst may be used as needed in the urethane formation reaction between the polyisocyanate component (a21) and the polyol component (a22).

[0116] Examples of the catalysts mentioned above include bismuth carboxylic acid compounds such as tris(2-ethylhexanoic acid)bismuth(III); organotin compounds such as dibutyltin dilaurate, dibutyltin dioctoate, and stanus octoate; and tertiary amine compounds such as triethylamine and triethylenediamine.

[0117] The urethane formation reaction is preferably carried out at 50 to 120°C.

[0118] In the synthesis of the isocyanate group-containing urethane prepolymer (a2), any organic solvent that is inert to the isocyanate and does not interfere with the urethane reaction can be used. Examples of such organic solvents include aromatic hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, and ketone solvents such as acetone and methyl ethyl ketone. Among these, ketone solvents and ester solvents can be preferably used from the viewpoint of water dispersion stability, etc.

[0119] These organic solvents can be used individually or in combination of two or more.

[0120] Furthermore, compound (b) having a polymerizable unsaturated group and lacking a hydroxyl group or having one hydroxyl group can be used as a substitute for the solvent. When using these compounds as a solvent, it is preferable to use compound (b2) having a polymerizable unsaturated group and lacking a hydroxyl group.

[0121] As the polymerization inhibitor, for example, known polymerization inhibitors such as phenolic hydroxyl group-containing compounds such as di-t-butylhydroxytoluene and methoxyphenol; carbonyl group-containing aromatic compounds such as benzoquinone; nitroso skeleton-containing compounds; and N-oxyl skeleton-containing compounds can be used.

[0122] From the viewpoint of manufacturability and other factors, the content ratio of the polyisocyanate component (a21) and the polyol component (a22) in the isocyanate group-containing urethane prepolymer (a2) is preferably in the range of 1 / 1.01 to 1 / 3.0 in terms of the molar ratio of active hydrogen groups in the polyol component (a22) to isocyanate groups in the polyisocyanate component (a21), and more preferably in the range of 1 / 1.05 to 1 / 2.0.

[0123] The number-average molecular weight of the above-mentioned isocyanate group-containing urethane prepolymer (a2) is preferably in the range of 1,000 to 20,000, more preferably in the range of 2,000 to 15,000, and even more preferably in the range of 2,500 to 10,000, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0124] In this specification, the average molecular weight is calculated from the chromatogram measured by gel permeation chromatography, using the molecular weight of standard polystyrene as a reference. The gel permeation chromatograph used was "HLC8120GPC" (manufactured by Tosoh Corporation). Four columns were used: "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL", and "TSKgel G-2000HXL" (all product names manufactured by Tosoh Corporation). The measurements were performed under the following conditions: mobile phase; tetrahydrofuran, measurement temperature; 40°C, flow rate; 1 mL / min, detector; radioisotope (RI).

[0125] Manufacturing process 3 Next, the compound (a1) having a secondary amino group and an alkoxysilyl group obtained in manufacturing step 1 is added to a mixture containing the isocyanate group-containing urethane prepolymer (a2) obtained in manufacturing step 2 and a compound (b) having a polymerizable unsaturated group and either no hydroxyl group or one hydroxyl group, and the isocyanate group-containing urethane prepolymer (a2) and the compound (a1) having a secondary amino group and an alkoxysilyl group are reacted to obtain the urethane resin portion (A).

[0126] The reaction between the isocyanate group-containing urethane prepolymer (a2) and the compound (a1) having a secondary amino group and an alkoxysilyl group is preferably carried out at a temperature in the range of 40 to 100°C.

[0127] The mass ratio (a1) / (a2) of the isocyanate group-containing urethane prepolymer (a2) and the compound (a1) having a secondary amino group and an alkoxysilyl group in the urethane resin portion (A) is preferably in the range of 1 / 99 to 20 / 80, more preferably in the range of 3 / 97 to 10 / 90, and even more preferably in the range of 4 / 96 to 7 / 93, from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance and glass adhesion of the formed coating film.

[0128] Furthermore, if necessary, the urethane resin portion (A) may be reacted with a compound (b1) having a polymerizable unsaturated group and one hydroxyl group to convert some or all of the terminal ends of the urethane resin portion (A) into polymerizable unsaturated groups.

[0129] Manufacturing process 4 Next, deionized water is added and emulsified to obtain an aqueous dispersion. If necessary, further chain extension reactions and solvent removal are carried out.

[0130] When adding deionized water, a neutralizing agent for the ion-forming groups may be added as needed.

[0131] The neutralizing agent is not particularly limited as long as it can neutralize the ion-forming group. Examples of basic compounds for neutralization include ammonia, diethylamine, ethylethanolamine, diethanolamine, triethanolamine, monoethanolamine, monopropanolamine, isopropanolamine, ethylaminoethylamine, hydroxyethylamine, triethylamine, tributylamine, dimethylethanolamine, diethylenetriamine, N-methylmorpholine, N-ethylmorpholine, and other organic amines; or alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. These neutralizing agents can be used individually or in combination of two or more.

[0132] It is preferable to use the above-mentioned neutralizing agent in an amount such that the pH of the acrylic urethane composite resin (AB) particle aqueous dispersion ultimately becomes approximately 6.0 to 9.0.

[0133] When adding the above-mentioned neutralizing agent, the amount of neutralizing agent added is preferably 0.1 to 1.5 equivalents relative to the acid group such as the carboxyl group, and more preferably 0.3 to 1.2 equivalents.

[0134] To improve the water dispersion stability of the acrylic urethane composite resin (AB) particle aqueous dispersion, emulsifiers such as surfactants may be used.

[0135] As the emulsifier mentioned above, well-known anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, polymeric surfactants, reactive surfactants, etc., can be used. When using these, anionic surfactants, nonionic surfactants, or cationic surfactants are preferred because they are less expensive and provide good emulsification.

[0136] Examples of the above-mentioned anionic surfactants include alkyl sulfates such as sodium dodecyl sulfate, potassium dodecyl sulfate, and ammonium dodecyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulfolycinolate; alkyl sulfonates such as alkali metal salts of sulfonated paraffins and ammonium salts of sulfonated paraffins; fatty acid salts such as sodium laurate, triethanolamine oleate, and toluethanolamine abietate; alkylaryl sulfonates such as sodium benzenesulfonate and alkali metal sulfates of alkaliphenol hydroxyethylene; high alkylnaphthalene sulfonates; naphthalene sulfonic acid formalin condensates; dialkyl sulfosuccinates; polyoxyethylene alkyl sulfate salts; and polyoxyethylene alkylaryl sulfate salts.

[0137] Examples of the nonionic surfactant include ethylene oxide and / or propylene oxide adducts of C1-C18 alcohols, ethylene oxide and / or propylene oxide adducts of alkylphenols, and ethylene oxide and / or propylene oxide adducts of alkylene glycols and / or alkylenediamines.

[0138] Examples of C1-C18 alcohols constituting the nonionic surfactant include methanol, ethanol, propanol, 2-propanol, butanol, 2-butanol, tertiary butanol, amyl alcohol, isoamyl alcohol, tertiary amyl alcohol, hexanol, octanol, decane alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, etc. Examples of alkylphenols include phenol, methylphenol, 2,4-ditertiary butylphenol, 2,5-ditertiary butylphenol, 3,5-ditertiary butylphenol, 4-(1,3-tetramethylbutyl)phenol, 4-isooctylphenol, 4-nonylphenol, 4-tertiary octylphenol, 4-dodecyl butylphenol. Examples of alkylene glycols include silphenol, 2-(3,5-dimethylheptyl)phenol, 4-(3,5-dimethylheptyl)phenol, naphthol, bisphenol A, bisphenol F, etc. Examples of alkylene glycols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, etc. Examples of alkylenediamines include those alkylene glycols in which the alcoholic hydroxyl group is replaced with an amino group. The ethylene oxide and propylene oxide adducts may be either random adducts or block adducts.

[0139] Examples of cationic surfactants include primary to tertiary amine salts, pyridinium salts, alkylpyridinium salts, and quaternary ammonium salts such as alkyl quaternary ammonium ammonium halides.

[0140] These surfactants can be used individually or in combination of two or more.

[0141] As for the emulsification method, dispersion using a conventional stirrer is possible, but to obtain a more uniform aqueous dispersion with finer particle sizes, a homomixer, homogenizer, disperser, line mixer, etc., can be used.

[0142] When performing the chain extension reaction (increasing molecular weight), a chain extension agent other than water may be added as needed to react the urethane resin portion (A) with the chain extension agent. As the chain extension agent, known chain extension agents having active hydrogen can be used. Specifically, examples include diamine compounds such as ethylenediamine, hexamethylenediamine, cyclohexanediamine, cyclohexylmethanediamine, and isophoronediamine; triamine compounds such as diethylenetriamine; tetraamine compounds such as triethylenetetraamine; amino alcohol compounds such as hydroxyethylhydrazine, hydroxyethyldiethylenetriamine, N-(2-aminoethyl)ethanol, 1,3-diamino-2-propanol, and 3-aminopropanediol; and hydrazine.

[0143] As the chain extender, from the viewpoint of abrasion resistance and glass adhesion of the formed coating film, trifunctional or higher amine compounds such as diethylenetriamine can be suitably used, and from the viewpoint of chipping resistance of the formed coating film, diamine compounds such as ethylenediamine can be suitably used.

[0144] Furthermore, as the chain extender, an amino alcohol compound such as N-(2-aminoethyl)ethanol can be used for the purpose of introducing reactive functional groups into the acrylic urethane composite resin (AB) particle aqueous dispersion.

[0145] Manufacturing process 5 Next, a polymerization initiator is added to the aqueous dispersion to carry out a polymerization reaction, thereby obtaining an aqueous dispersion of acrylic urethane composite resin (AB) particles containing a urethane resin portion (A) and an acrylic resin portion (B).

[0146] Examples of polymerization initiators include organic peroxides such as benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, and diisopropylbenzene hydroperoxide; azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile), and azobis(2-methyl Examples of polymerization initiators include azo compounds such as propionnitrile, azobis(2-methylbutyronitrile), 4,4'-azobis(4-cyanobutanoic acid), dimethylazobis(2-methylpropionate), azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], azobis{2-methyl-N-[2-(1-hydroxybutyl)]-propionamide}, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide]; and persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate. These polymerization initiators can be used individually or in combination of two or more. In addition, a reducing agent such as sugar, sodium formaldehyde sulfoxylate, or an iron complex can be used in combination with the above polymerization initiator as needed to form a redox initiator.

[0147] The amount of polymerization initiator used is generally preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and more preferably 5% by mass or less, and more preferably 3% by mass or less, based on the total amount of monomers used. The method of adding the polymerization initiator is not particularly limited and can be appropriately selected depending on its type and amount. For example, it can be included in the monomer mixture or aqueous medium in advance, added all at once during polymerization, or added dropwise.

[0148] The polymerization reaction can be carried out by conventionally known methods, such as emulsion polymerization in water or self-emulsification.

[0149] The acrylic urethane composite resin (AB) synthesized in the above manufacturing processes 1 to 5 is synthesized as a dispersion in an aqueous solvent and has a particulate form.

[0150] Here, an aqueous solvent refers to a solvent whose main component is water (for example, a solvent in which 70-100% by mass is water).

[0151] The average particle size of the acrylic urethane composite resin (AB) particles is preferably in the range of 10 to 5000 nm, more preferably in the range of 10 to 1000 nm, particularly preferably in the range of 20 to 500 nm, and even more preferably in the range of 50 to 140 nm, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0152] The average particle size of the above-mentioned acrylic urethane composite resin (AB) particles can be adjusted to a desired average particle size by controlling particle size factors such as the composition of the raw materials (polyisocyanate component, polyol component, amine component, etc.), the type of emulsifier, the amount of emulsifier, the proportion of emulsifier added, the type of neutralizing agent, and the amount of neutralizing agent.

[0153] In this specification, the average particle size of acrylic urethane composite resin (AB) particles is the value measured at 20°C after dilution with deionized water using a dynamic light scattering particle size distribution analyzer. As a dynamic light scattering particle size distribution analyzer, for example, "ELSZ-2000" (product name, manufactured by Otsuka Electronics Co., Ltd.) can be used.

[0154] The hydroxyl value of the above-mentioned urethane resin portion (A) is preferably in the range of 0 to 45 mgKOH / g, more preferably in the range of 0 to 30 mgKOH / g, and even more preferably in the range of 0 to 25 mgKOH / g, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0155] The acid value of the urethane resin portion (A) is preferably in the range of 3.0 to 75 mgKOH / g, more preferably in the range of 10 to 60 mgKOH / g, and even more preferably in the range of 20 to 40 mgKOH / g, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0156] The hydroxyl value of the acrylic resin portion (B) is preferably in the range of 0.5 to 90 mgKOH / g, more preferably in the range of 2.0 to 65 mgKOH / g, and even more preferably in the range of 10 to 45 mgKOH / g, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0157] The acid value of the acrylic resin portion (B) is preferably in the range of 0.7 to 80 mgKOH / g, more preferably in the range of 3.5 to 40 mgKOH / g, and even more preferably in the range of 7.5 to 25 mgKOH / g, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0158] The hydroxyl value of the acrylic urethane composite resin (AB) is preferably in the range of 0 to 100 mg KOH / g, more preferably in the range of 0 to 50 mg KOH / g, and even more preferably in the range of 0 to 10 mg KOH / g, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0159] The acid value of the above-mentioned acrylic urethane composite resin (AB) is preferably in the range of 5 to 40 mg KOH / g, more preferably in the range of 5 to 30 mg KOH / g, and even more preferably in the range of 7 to 30 mg KOH / g, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0160] The mass ratio (B) / (A) of the acrylic resin portion (B) and the urethane resin portion (A) in the acrylic urethane composite resin (AB) particle aqueous dispersion is preferably in the range of 20 / 80 to 80 / 20, more preferably in the range of 30 / 70 to 70 / 30, and particularly preferably in the range of 40 / 60 to 60 / 40, from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0161] The solid content concentration in the acrylic urethane composite resin (AB) particle aqueous dispersion is preferably in the range of 20 to 50% by mass, and more preferably in the range of 30 to 50% by mass. When the solid content concentration is 50% by mass or less, emulsification is facilitated, and an aqueous dispersion can be easily obtained. When the solid content concentration is 20% by mass or more, the amount of solvent components is reduced, so the solid content concentration of the aqueous coating composition can be increased.

[0162] In this specification, "solid content" refers to non-volatile components such as resins, curing agents, and pigments that remain after drying at 110°C for 1 hour. The solid content can be determined, for example, by weighing a sample into a heat-resistant container such as an aluminum foil cup, spreading the sample on the bottom surface of the container, drying it at 110°C for 1 hour, and then weighing the mass of the components remaining after drying.

[0163] Furthermore, in this specification, "solid content concentration" refers to the mass percentage of the solid content in the composition. Therefore, the solid content concentration of a composition can be calculated, for example, by weighing 1.0 g of the composition into a heat-resistant container such as an aluminum foil cup, spreading the composition on the bottom surface of the container, drying it at 110°C for 1 hour, weighing the mass of the components remaining in the composition after drying, and determining the ratio of the mass of the components remaining after drying to the total mass of the composition before drying.

[0164] In an aqueous dispersion of acrylic urethane composite resin (AB) particles, by adjusting the composition of the urethane resin portion (A), the composition of the acrylic resin portion (B), the reaction conditions, etc., an aqueous dispersion of acrylic urethane composite resin (AB) having a desired form, such as a core-shell structure comprising at least two layers, a core layer containing either the urethane resin portion (A) or the acrylic resin portion (B), and a shell layer containing either the urethane resin portion (A) or the acrylic resin portion (B), or a form in which part or all of the urethane resin portion (A) and the acrylic resin portion (B) are mixed, can be obtained.

[0165] Specifically, a core-shell structure refers to a structure in which components with different resin compositions exist within the same particle, resulting in a structure where the central part (core) and the outer shell (shell) are made of different resin compositions.

[0166] The above-mentioned acrylic urethane composite resin (AB) particle aqueous dispersion is preferably an acrylic urethane composite resin (AB') particle aqueous dispersion having a core-shell structure consisting of a shell portion made of the urethane resin portion (A) and a core portion made of the acrylic resin portion (B), from the viewpoint of storage stability of the resulting aqueous paint composition and abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0167] Aqueous dispersion of acrylic urethane composite resin (AB') particles having a core-shell structure Aqueous dispersions of acrylic urethane composite resin (AB') particles having a core-shell structure are typically synthesized as dispersions in aqueous solvents.

[0168] The aqueous dispersion of acrylic urethane composite resin (AB') particles having a core-shell structure is preferably dispersed in an aqueous medium as particles having a structure in which the urethane resin portion (A) constituting the shell portion is positioned around the acrylic resin portion (B) constituting the core portion, acting as a dispersion stabilizer. In other words, it is preferable that the particles are dispersed in an aqueous solvent in a form having a core-shell structure with the urethane resin portion (A) constituting the shell portion on the outside and the acrylic resin portion (B) constituting the core portion on the inside. It is believed that the particles actually have almost such a particle morphology.

[0169] The above-described core-shell structure is typically a layered structure in which the core is completely covered by the shell. However, depending on the mass ratio of the core and shell, and other conditions, the shell may not be sufficient to form a layered structure. In such cases, it is not necessary to have a complete layered structure as described above, and a structure in which the shell covers only a portion of the core may be used.

[0170] As a method for producing an aqueous dispersion of acrylic urethane composite resin (AB') particles having a core-shell structure, conventionally known methods for producing acrylic urethane composite resins can be used, provided that the material can have a core-shell structure. For example, in step 2 of the production process for the aqueous dispersion of acrylic urethane composite resin (AB) particles, a compound having both active hydrogen groups and ion-forming groups can be used as a component of the urethane resin portion (A) to produce an aqueous dispersion of acrylic urethane composite resin (AB') particles having a core-shell structure.

[0171] As compounds having both active hydrogen groups and ion-forming groups, those exemplified in the acrylic urethane composite resin (AB) particle aqueous dispersion can be used, and these can be used individually or in combination of two or more.

[0172] In particular, as compounds having both the active hydrogen group and the ion-forming group, compounds having two or more hydroxyl groups and one or more carboxyl groups in one molecule, and compounds having two or more hydroxyl groups and one or more sulfonic acid groups in one molecule can be suitably used.

[0173] As the compounds having two or more hydroxyl groups and one or more carboxyl groups in a single molecule, the compounds having two or more hydroxyl groups and one or more carboxyl groups in a single molecule, as exemplified in the acrylic urethane composite resin (AB) particle aqueous dispersion, can be used, and these can be used alone or in combination of two or more.

[0174] As the compounds having two or more hydroxyl groups and one or more sulfonic acid groups in a single molecule, the compounds having two or more hydroxyl groups and one or more sulfonic acid groups in a single molecule, as exemplified in the acrylic urethane composite resin (AB) particle aqueous dispersion, can be used, and these can be used alone or in combination of two or more.

[0175] As for the compound having both the active hydrogen group and the ion-forming group, it is preferable to use a compound having two or more hydroxyl groups and one or more carboxyl groups in its molecule, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0176] If the urethane resin portion (A) constituting the shell portion contains a compound having two or more hydroxyl groups and one or more carboxyl groups, the content thereof is preferably in the range of 1 to 30% by mass, more preferably in the range of 1 to 25% by mass, and even more preferably in the range of 1 to 20% by mass, relative to the total amount of compounds constituting the polyol component (a22), from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0177] The average particle size of the acrylic urethane composite resin (AB') particles having the core-shell structure is preferably in the range of 10 to 5000 nm, more preferably in the range of 10 to 1000 nm, particularly preferably in the range of 20 to 500 nm, and even more preferably in the range of 50 to 140 nm, from the viewpoint of the storage stability of the resulting aqueous coating composition.

[0178] The average particle size of acrylic urethane composite resin (AB') particles having a core-shell structure can be adjusted to a desired average particle size by controlling particle size factors such as the composition of raw materials (polyisocyanate component, polyol component, amine component, etc.), the type of emulsifier, the amount of emulsifier, the proportion of emulsifier added, the type of neutralizing agent, and the amount of neutralizing agent.

[0179] The hydroxyl value of the urethane resin portion (A) constituting the shell portion described above is preferably in the range of 0 to 45 mgKOH / g, more preferably in the range of 0 to 30 mgKOH / g, and even more preferably in the range of 0 to 25 mgKOH / g, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0180] The acid value of the urethane resin portion (A) constituting the shell portion is preferably in the range of 3.0 to 75 mgKOH / g, more preferably in the range of 10 to 60 mgKOH / g, and even more preferably in the range of 20 to 40 mgKOH / g, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0181] The hydroxyl value of the acrylic resin portion (B) constituting the core is preferably in the range of 0.5 to 90 mgKOH / g, more preferably in the range of 2.0 to 65 mgKOH / g, and even more preferably in the range of 10 to 45 mgKOH / g, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0182] The acid value of the acrylic resin portion (B) constituting the core portion described above is preferably in the range of 0.7 to 80 mgKOH / g, more preferably in the range of 3.5 to 40 mgKOH / g, and even more preferably in the range of 7.5 to 25 mgKOH / g, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0183] The hydroxyl value of the acrylic urethane composite resin (AB') having the core-shell structure is preferably in the range of 0 to 100 mgKOH / g, more preferably in the range of 0 to 50 mgKOH / g, and even more preferably in the range of 0 to 10 mgKOH / g, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0184] The acid value of the acrylic urethane composite resin (AB') having the above-described core-shell structure is preferably in the range of 5 to 40 mgKOH / g, more preferably in the range of 5 to 30 mgKOH / g, and even more preferably in the range of 7 to 30 mgKOH / g, from the viewpoint of the storage stability of the resulting aqueous paint composition.

[0185] The mass ratio (B) / (A) of the acrylic resin portion (B) constituting the core and the urethane resin portion (A) constituting the shell of the acrylic urethane composite resin (AB') particle aqueous dispersion having the core-shell structure is preferably in the range of 20 / 80 to 80 / 20, more preferably in the range of 30 / 70 to 70 / 30, and particularly preferably in the range of 40 / 60 to 60 / 40, from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0186] The solid content concentration in the aqueous dispersion of acrylic urethane composite resin (AB') particles having the above-described core-shell structure is preferably in the range of 20 to 50% by mass, and more preferably in the range of 30 to 50% by mass. When the solid content concentration is 50% by mass or less, emulsification is facilitated, and an aqueous dispersion can be easily obtained. When the solid content concentration is 20% by mass or more, the amount of solvent components is reduced, so the solid content concentration of the aqueous coating composition can be increased.

[0187] [Water-based paint composition] The aqueous coating composition of the present invention contains an aqueous dispersion of acrylic urethane composite resin (AB) particles, and optionally contains at least one resin selected from acrylic resin (C) and polyester resin (D), and a curing agent (E).

[0188] In the aqueous coating composition of the present invention, the content of the acrylic urethane composite resin (AB) particle aqueous dispersion is preferably in the range of 10 to 70% by mass, more preferably in the range of 15 to 60% by mass, and even more preferably in the range of 20 to 55% by mass, based on the amount of resin solids in the aqueous coating composition, from the viewpoint of chipping resistance and glass adhesion of the formed coating film.

[0189] When the above-mentioned aqueous dispersion of acrylic urethane composite resin (AB) particles contains an aqueous dispersion of acrylic urethane composite resin (AB') particles having the core-shell structure, the content of the aqueous dispersion of acrylic urethane composite resin (AB') particles having the core-shell structure is preferably in the range of 50 to 100% by mass, more preferably in the range of 70 to 100% by mass, and even more preferably in the range of 90 to 100% by mass, based on the total solid content of the aqueous dispersion of acrylic urethane composite resin (AB) particles, from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0190] Acrylic resin (C) As the acrylic resin (C), any water-soluble or water-dispersible acrylic resin that has been conventionally used in water-based paints and is known for itself can be used.

[0191] The acrylic resin (C) preferably has crosslinkable functional groups that can react with the curing agent (E) described below. Examples of such crosslinkable functional groups include hydroxyl groups, carboxyl groups, and alkoxysilyl groups.

[0192] Acrylic resin (C) can be produced, for example, by copolymerizing polymerizable unsaturated monomers using methods known to themselves, such as solution polymerization in an organic solvent or emulsion polymerization in water.

[0193] Examples of polymerizable unsaturated monomers that can be used include the monomers listed below (i) to (xxi). These polymerizable unsaturated monomers can be used individually or in combination of two or more. (i) Alkyl or cycloalkyl (meth)acrylates: for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, etc. (ii) Polymerizable unsaturated monomers having an isobornyl group: isobornyl (meth)acrylate, etc. (iii) Polymerizable unsaturated monomers having an adamantyl group: adamantyl (meth)acrylate, etc. (iv) Polymerizable unsaturated monomers having a tricyclodecenyl group: tricyclodecenyl (meth)acrylate, etc. (v) Polymerizable unsaturated monomers containing aromatic rings: benzyl (meth)acrylate, styrene, α-methylstyrene, vinyltoluene, etc. (vi) Polymerizable unsaturated monomers having an alkoxysilyl group: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, etc. (vii) Polymerizable unsaturated monomers having a fluorinated alkyl group: Perfluoroalkyl (meth)acrylates such as perfluorobutylethyl (meth)acrylate and perfluorooctylethyl (meth)acrylate; fluoroolefins, etc. (viii) A polymerizable unsaturated monomer having a photopolymerizable functional group such as a maleimide group. (ix) Vinyl compounds: N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, etc. (x) Carboxylate-containing polymerizable unsaturated monomers: (meth)acrylic acid, maleic acid, crotonic acid, β-carboxyethyl (meth)acrylate, etc. (xi) Nitrogen-containing polymerizable unsaturated monomers: (meth)acrylonitrile, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, adducts of glycidyl (meth)acrylate with amine compounds, etc. (xii) Polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule: allyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, etc. (xiii) Polymerizable unsaturated monomers containing epoxy groups: glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, allyl glycidyl ether, etc. (xiv) A (meth)acrylate having a polyoxyethylene chain with an alkoxy group at the molecular terminus. (xv) Polymerizable unsaturated monomers having a sulfonic acid group: 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth)acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc.; sodium salts and ammonium salts of these sulfonic acids, etc. (xvi) Polymerizable unsaturated monomers having a phosphate group: acid phosphooxyethyl (meth)acrylate, acid phosphooxypropyl (meth)acrylate, acid phosphooxypoly(oxyethylene) glycol (meth)acrylate, acid phosphooxypoly(oxypropylene) glycol (meth)acrylate, etc. (xvii) Polymerizable unsaturated monomers having UV-absorbing functional groups: 2-hydroxy-4(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, etc. (xviii) Photostable polymerizable unsaturated monomers: 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, etc. (xix) Polymerizable unsaturated monomers having a carbonyl group: acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, vinyl alkyl ketones having 4 to 7 carbon atoms (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone), etc. (xx) Polymerizable unsaturated monomers having an acid anhydride group: maleic anhydride, itaconic anhydride, citraconic anhydride, etc. (xxi) Hydroxyl group-containing polymerizable unsaturated monomers: Monoesters of (meth)acrylic acid and dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone modified forms of the monoesters of (meth)acrylic acid and dihydric alcohols having 2 to 8 carbon atoms; N-hydroxymethyl (meth)acrylamide; allyl alcohol; and (meth)acrylates having polyoxyethylene chains with hydroxyl groups at the molecular ends. However, monomers that fall under "(xvii) Polymerizable unsaturated monomers having UV-absorbing functional groups" are excluded from the above "Hydroxy group-containing polymerizable unsaturated monomers," even if they contain hydroxyl groups.

[0194] When the acrylic resin (C) contains the hydroxyl group-containing polymerizable unsaturated monomer as a component of the acrylic resin (C), the proportion of the hydroxyl group-containing polymerizable unsaturated monomer used is preferably in the range of 1 to 50% by mass, more preferably in the range of 2 to 40% by mass, and even more preferably in the range of 3 to 30% by mass, based on the total amount of monomer components.

[0195] When the above-mentioned acrylic resin (C) contains the carboxyl group-containing polymerizable unsaturated monomer as a component of the acrylic resin (C), the proportion of the carboxyl group-containing polymerizable unsaturated monomer used is preferably in the range of 1 to 50% by mass, more preferably in the range of 1.5 to 40% by mass, and even more preferably in the range of 2 to 30% by mass, based on the total amount of monomer components.

[0196] When the above-mentioned acrylic resin (C) contains the alkoxysilyl group-containing polymerizable unsaturated monomer as a component of the acrylic resin (C), the proportion of the alkoxysilyl group-containing polymerizable unsaturated monomer used is preferably in the range of 1 to 70% by mass, more preferably in the range of 1.5 to 60% by mass, and even more preferably in the range of 2 to 40% by mass, based on the total amount of monomer components.

[0197] The acrylic resin (C) described above preferably has a hydroxyl value in the range of 1 to 200 mg KOH / g, more preferably in the range of 2 to 180 mg KOH / g, and even more preferably in the range of 5 to 150 mg KOH / g, from the viewpoint of the curability, abrasion resistance, chipping resistance, and glass adhesion of the formed coating film.

[0198] Furthermore, from the viewpoint of storage stability of the resulting aqueous paint composition, the acid value of the acrylic resin (C) is preferably in the range of 1 to 150 mg KOH / g, more preferably in the range of 5 to 100 mg KOH / g, and even more preferably in the range of 5 to 80 mg KOH / g.

[0199] When the aqueous coating composition of the present invention contains the above-mentioned acrylic resin (C), the content of the acrylic resin (C) is preferably in the range of 2 to 70% by mass, more preferably in the range of 5 to 60% by mass, and even more preferably in the range of 10 to 50% by mass, based on the amount of resin solids in the aqueous coating composition.

[0200] Polyester resin (D) As the polyester resin (D), any water-soluble or water-dispersible polyester resin that has been conventionally used in water-based paints and is known for itself can be used.

[0201] The polyester resin (D) preferably has crosslinkable functional groups that can react with the curing agent (E) described below. Examples of such crosslinkable functional groups include hydroxyl groups and carboxyl groups.

[0202] Polyester resin (D) can usually be produced by an esterification or transesterification reaction between an acid component and an alcohol component.

[0203] As the above-mentioned acid component, compounds commonly used as acid components in the manufacture of polyester resins can be used. Examples of such acid components include aliphatic polybasic acids, alicyclic polybasic acids, aromatic polybasic acids, and the like.

[0204] The above-mentioned aliphatic polybasic acids are generally aliphatic compounds having two or more carboxyl groups in one molecule, acid anhydrides of the aliphatic compounds, and esters of the aliphatic compounds. Examples of aliphatic polybasic acids include aliphatic polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanediic acid, dodecanediic acid, brassic acid, octadecanediic acid, citric acid, and butanetetracarboxylic acid; anhydrides of the aliphatic polycarboxylic acids; and esters of the aliphatic polycarboxylic acids of lower alkyl groups having approximately 1 to 4 carbon atoms. The above-mentioned aliphatic polybasic acids can be used alone or in combination of two or more types.

[0205] As the above-mentioned aliphatic polybasic acid, it is preferable to use adipic acid and / or adipic anhydride from the viewpoint of chipping resistance of the formed coating film.

[0206] The above-mentioned alicyclic polybasic acids are generally compounds having one or more alicyclic structures and two or more carboxyl groups in one molecule, acid anhydrides of the same, and esters of the same. The alicyclic structure is mainly a 4- to 6-membered ring structure. Examples of alicyclic polybasic acids include alicyclic polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, and 1,3,5-cyclohexanetricarboxylic acid; anhydrides of the alicyclic polycarboxylic acids; and esters of lower alkyl groups having approximately 1 to 4 carbon atoms of the alicyclic polycarboxylic acids. The above-mentioned alicyclic polybasic acids can be used alone or in combination of two or more.

[0207] As the above-mentioned alicyclic polybasic acid, from the viewpoint of chipping resistance of the formed coating film, it is preferable to use 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid anhydride, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, and 4-cyclohexene-1,2-dicarboxylic acid anhydride, and among these, it is more preferable to use 1,2-cyclohexanedicarboxylic acid and / or 1,2-cyclohexanedicarboxylic acid anhydride.

[0208] The above-mentioned aromatic polybasic acids generally include aromatic compounds having two or more carboxyl groups in one molecule, acid anhydrides of the aromatic compounds, and esterified products of the aromatic compounds, such as aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, trimellitic acid, and pyromellitic acid; anhydrides of the aromatic polycarboxylic acids; and esterified products of the aromatic polycarboxylic acids of lower alkyl groups having approximately 1 to 4 carbon atoms. The above-mentioned aromatic polybasic acids can be used alone or in combination of two or more types.

[0209] As the above aromatic polybasic acid, it is preferable to use phthalic acid, phthalic anhydride, isophthalic acid, trimellitic acid, or trimellitic anhydride.

[0210] Furthermore, acid components other than the above-mentioned aliphatic polybasic acids, alicyclic polybasic acids, and aromatic polybasic acids can also be used. Such acid components are not particularly limited and include, for example, fatty acids such as coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor oil fatty acid, and safflower oil fatty acid; monocarboxylic acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexanoic acid, and 10-phenyloctadecanoic acid; and hydroxycarboxylic acids such as lactic acid, 3-hydroxybutanoic acid, and 3-hydroxy-4-ethoxybenzoic acid. These acid components can be used individually or in combination of two or more.

[0211] As the alcohol component, polyhydric alcohols having two or more hydroxyl groups in one molecule can be suitably used. Examples of such polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, and 1,5-butyl-2-ethyl-1,3-propanediol. Pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecanediethanol Examples include dihydric alcohols such as neopentyl glycol hydroxypivalate, hydrogenated bisphenol A, hydrogenated bisphenol F, and dimethylolpropionic acid; polylactone diols obtained by adding lactone compounds such as ε-caprolactone to these dihydric alcohols; ester diol compounds such as bis(hydroxyethyl) terephthalate; polyether diol compounds such as alkylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene ether glycol; trihydric or higher alcohols such as glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris(2-hydroxyethyl)isocyanuric acid, sorbitol, and mannitol; polylactone polyol compounds obtained by adding lactone compounds such as ε-caprolactone to these trihydric or higher alcohols; and fatty acid esters of glycerin.

[0212] Furthermore, alcohol components other than the polyhydric alcohols mentioned above can also be used. Such alcohol components are not particularly limited and include, for example, monoalcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, stearyl alcohol, and 2-phenoxyethanol; and alcohol compounds obtained by reacting monoepoxy compounds such as propylene oxide, butylene oxide, and "Cardura E10P" (trade name, manufactured by HEXION, a glycidyl ester of a synthetic highly branched saturated fatty acid) with an acid.

[0213] The method for producing polyester resin is not particularly limited and can be carried out according to conventional methods. For example, polyester resin can be produced by heating the acid component and the alcohol component in a nitrogen stream at approximately 150 to 250°C for approximately 5 to 10 hours to carry out an esterification reaction or transesterification reaction between the acid component and the alcohol component.

[0214] When carrying out the esterification or transesterification reaction of the above acid and alcohol components, they may be added to the reaction vessel all at once, or one or both may be added in several stages. Alternatively, a hydroxyl group-containing polyester resin may be synthesized first, and then the obtained hydroxyl group-containing polyester resin may be reacted with an acid anhydride to perform half-esterification to obtain a carboxyl group-containing polyester resin. Alternatively, a carboxyl group-containing polyester resin may be synthesized first, and then the above alcohol component may be added to obtain a hydroxyl group-containing polyester resin.

[0215] In the aforementioned esterification or transesterification reaction, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used as catalysts to accelerate the reaction.

[0216] Furthermore, the polyester resin can be modified with fatty acids, monoepoxy compounds, polyisocyanate compounds, acrylic resins, etc., during or after its preparation.

[0217] Examples of the above fatty acids include coconut oil fatty acids, cottonseed oil fatty acids, hemp seed oil fatty acids, rice bran oil fatty acids, fish oil fatty acids, tall oil fatty acids, soybean oil fatty acids, linseed oil fatty acids, tung oil fatty acids, rapeseed oil fatty acids, castor oil fatty acids, dehydrated castor oil fatty acids, and safflower oil fatty acids. As for the above monoepoxy compound, for example, "Cardura E10P" (trade name, manufactured by HEXION, a glycidyl ester of synthetic highly branched saturated fatty acids) can be suitably used.

[0218] Furthermore, examples of the polyisocyanate compounds include aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; and lipid diisocyanate compounds such as hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,3-(isocyanatomethyl)cyclohexane. Examples include cyclic diisocyanate compounds; aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate; organic polyisocyanates themselves, such as trivalent or higher polyisocyanates like lysine triisocyanate; adducts of these organic polyisocyanates with polyhydric alcohols, low molecular weight polyester resins, water, etc.; and cyclized polymers (e.g., isocyanurates) and biuret-type adducts of these organic polyisocyanates. These polyisocyanate compounds can be used individually or in combination of two or more.

[0219] Furthermore, known methods can be used to modify the polyester resin with the acrylic resin. Examples include polymerizing a mixture of a polymerizable unsaturated group-containing polyester resin and a polymerizable unsaturated monomer, or using a resin-to-resin reaction between the polyester resin and the acrylic resin.

[0220] The hydroxyl value of the above polyester resin (D) is preferably in the range of 1 to 250 mg KOH / g, more preferably in the range of 2 to 200 mg KOH / g, and even more preferably in the range of 5 to 180 mg KOH / g.

[0221] Furthermore, the acid value of the polyester resin (D) is preferably in the range of 1 to 150 mg KOH / g, more preferably in the range of 2 to 100 mg KOH / g, and even more preferably in the range of 2 to 80 mg KOH / g.

[0222] Furthermore, the number-average molecular weight of the polyester resin (D) is preferably in the range of 500 to 50,000, more preferably in the range of 800 to 30,000, and even more preferably in the range of 1,000 to 10,000.

[0223] When the aqueous coating composition of the present invention contains the polyester resin (D), the content of the polyester resin (D) is preferably in the range of 2 to 70% by mass, more preferably in the range of 5 to 50% by mass, and even more preferably in the range of 10 to 40% by mass, based on the amount of resin solids in the aqueous coating composition.

[0224] Hardener (E) The curing agent (E) is a compound that reacts with the crosslinkable functional groups in the acrylic urethane composite resin (AB) particle aqueous dispersion, acrylic resin (C), and polyester resin (D) to cure the aqueous coating composition. The curing agent (E) can be used alone or in combination of two or more types.

[0225] Examples of curing agents (E) include polycarbodiimide compounds, amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, hydrazide group-containing compounds, and semicarbazide group-containing compounds.

[0226] In particular, from the viewpoint of the abrasion resistance, chipping resistance, and glass adhesion of the formed coating film, it is preferable to include at least one selected from polycarbodiimide compounds (E1), amino resins (E2), polyisocyanate compounds (E3), and blocked polyisocyanate compounds (E4), more preferably to include at least one selected from polycarbodiimide compounds (E1), amino resins (E2), and blocked polyisocyanate compounds (E4), and even more preferably to include polycarbodiimide compounds (E1).

[0227] The polycarbodiimide compound (E1) is a compound having at least two carbodiimide groups in one molecule, and for example, a compound obtained by decarbonizing the isocyanate groups of an isocyanate group-containing compound can be used.

[0228] As the polycarbodiimide compound (E1) mentioned above, it is preferable to use a water-soluble or water-dispersible polycarbodiimide compound from the viewpoint of storage stability of the resulting aqueous coating composition and abrasion resistance and glass adhesion of the formed coating film. The water-soluble or water-dispersible polycarbodiimide compound can be used without particular limitations, as long as it is a polycarbodiimide compound that can be stably dissolved or dispersed in an aqueous medium.

[0229] Specifically, examples of the above-mentioned water-soluble polycarbodiimide compounds include "Carbodilite SV-02," "Carbodilite V-02," "Carbodilite V-02-L2," and "Carbodilite V-04" (all manufactured by Nisshinbo Co., Ltd., trade names). Furthermore, examples of the above-mentioned water-dispersible polycarbodiimide compounds include "Carbodilite E-01," "Carbodilite E-02," and "Carbodilite E-05" (all manufactured by Nisshinbo Co., Ltd., trade names).

[0230] If the curing agent (E) contains a polycarbodiimide compound (E1), the content of the polycarbodiimide compound (E1) is preferably in the range of 10 to 80% by mass, more preferably in the range of 15 to 70% by mass, and even more preferably in the range of 20 to 65% by mass, based on the total solid content of the curing agent (E), from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance and glass adhesion of the formed coating film.

[0231] As the amino resin (E2), a partially methylolated amino resin or a fully methylolated amino resin obtained by the reaction of an amino component and an aldehyde component can be used. Examples of amino components include melamine, urea, benzoguanamine, acetoganaamine, steroguanamine, spiloganamine, and dicyandiamide. Examples of aldehyde components include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.

[0232] Furthermore, a methylolated amino resin can also be used in which the methylol group has been partially or completely etherified with a suitable alcohol. Examples of alcohols that can be used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethyl-1-butanol, and 2-ethyl-1-hexanol.

[0233] As the amino resin, melamine resin is preferred. Particularly preferred are methyl etherified melamine resins, in which the methylol groups of a partially or completely methylolated melamine resin are partially or completely etherified with methyl alcohol; butyl etherified melamine resins, in which the methylol groups of a partially or completely methylolated melamine resin are partially or completely etherified with butyl alcohol; and methyl-butyl mixed etherified melamine resins, in which the methylol groups of a partially or completely methylolated melamine resin are partially or completely etherified with methyl alcohol and butyl alcohol. Methyl-butyl mixed etherified melamine resin is more preferred.

[0234] The melamine resin described above preferably has a weight-average molecular weight of 400 to 6,000, more preferably 500 to 4,000, and even more preferably 600 to 3,000.

[0235] Commercially available melamine resins can be used. Examples of commercially available product names include "Cymel 202", "Cymel 203", "Cymel 238", "Cymel 250", "Cymel 251", "Cymel 303", "Cymel 323", "Cymel 324", "Cymel 325", "Cymel 327", "Cymel 350", "Cymel 385", "Cymel 1156", "Cymel 1158", "Cymel 1116", "Cymel 1130" (all manufactured by Ornex Japan Co., Ltd.), "Uban 120", "Uban 20HS", "Uban 20SE60", "Uban 2021", "Uban 2028", and "Uban 28-60" (all manufactured by Mitsui Chemicals, Inc.).

[0236] When the aqueous coating composition of the present invention contains the above-mentioned melamine resin, the aqueous coating composition may contain, as a curing catalyst, a sulfonic acid such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, or dinonylnaphthalenesulfonic acid; a neutralized salt of the sulfonic acid and an amine; a neutralized salt of a phosphate ester compound and an amine, etc.

[0237] If the curing agent (E) contains an amino resin (E2), the content of the amino resin (E2) is preferably in the range of 10 to 80% by mass, more preferably in the range of 15 to 70% by mass, and even more preferably in the range of 20 to 65% by mass, based on the total solid content of the curing agent (E), from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance and glass adhesion of the formed coating film.

[0238] The polyisocyanate compound (E3) is a compound having at least two isocyanate groups in one molecule, and examples include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic aliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of said polyisocyanates.

[0239] Examples of the above aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, diisocyanate dimer, and methyl 2,6-diisocyanatohexanoate (common name: lysine). Examples include aliphatic diisocyanates such as diisocyanates; and aliphatic triisocyanates such as 2-isocyanatoethyl 2,6-diisocyanatohexanoate, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane.

[0240] Examples of the alicyclic polyisocyanates include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), and 2-methyl-1,3-cyclohexylene diisocyanate. Alicyclic diisocyanates such as nate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or mixtures thereof, methylenebis(4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)- 2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 6-(2-iso Examples include alicyclic triisocyanates such as cyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, and 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane.

[0241] Examples of the aforementioned aromatic aliphatic polyisocyanates include aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; and aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.

[0242] Examples of the aromatic polyisocyanates include aromatic diisocyanates such as m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, 2,4-tolylenediisocyanate (common name: 2,4-TDI) or 2,6-tolylenediisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidinediisocyanate, and 4,4'-diphenyletherdiisocyanate; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; and aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate.

[0243] Furthermore, examples of derivatives of the polyisocyanate include dimers, trimers, biuret, allophanate, uretodione, uretoimine, isocyanurate, oxadiazinetrione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI), crude TDI, and the like.

[0244] The polyisocyanates and their derivatives may be used individually or in combination of two or more. Among these polyisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and their derivatives are preferred.

[0245] Furthermore, as the polyisocyanate compound, a prepolymer obtained by reacting the above-mentioned polyisocyanate and its derivatives with a compound that can react with the polyisocyanate under conditions of excess isocyanate groups may be used. Examples of compounds that can react with the polyisocyanate include compounds having active hydrogen groups such as hydroxyl groups and amino groups, and specifically, for example, polyhydric alcohols, low molecular weight polyester resins, amines, water, etc. can be used.

[0246] If the curing agent (E) contains a polyisocyanate compound (E3), the content of the polyisocyanate compound (E3) is preferably in the range of 10 to 80% by mass, more preferably in the range of 15 to 70% by mass, and even more preferably in the range of 20 to 65% by mass, based on the total solid content of the curing agent (E), from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance and glass adhesion of the formed coating film.

[0247] Furthermore, as the polyisocyanate compound, a polymer of an isocyanate group-containing polymerizable unsaturated monomer, or a copolymer of the isocyanate group-containing polymerizable unsaturated monomer and a polymerizable unsaturated monomer other than the isocyanate group-containing polymerizable unsaturated monomer may be used.

[0248] The blocked polyisocyanate compound (E4) is a compound obtained by blocking the isocyanate group of the polyisocyanate compound (E3) with a blocking agent.

[0249] Examples of the above-mentioned blocking agents include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, and lauryl alcohol; ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylolmelamine, diacetone alcohol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate. Alcohol-based compounds such as droxyethyl methacrylate; oxime-based compounds such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; active methylene-based compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, and methylthiophenone. Mercaptan-based compounds such as ethylthiophenol; acid amide-based compounds such as acetanilide, acetanisidide, acetotoluid, acrylamide, methacrylamide, acetic acid amide, stearic acid amide, and benzamide; imide-based compounds such as succinimide, phthalimide, and maleimide; amine-based compounds such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine; imidazole-based compounds such as imidazole and 2-ethylimidazole;Examples of azole compounds include urea-based compounds such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea; carbamic acid ester compounds such as phenyl N-phenylcarbamate; imine-based compounds such as ethyleneimine and propyleneimine; sulfite-based compounds such as sodium bisulfite and potassium bisulfite; and azole compounds. Examples of the above-mentioned azole compounds include pyrazoles or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; imidazoles or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenylimidazole; and imidazoline derivatives such as 2-methylimidazoline and 2-phenylimidazoline.

[0250] Among these, preferred blocking agents include active methylene-based blocking agents, pyrazoles, or pyrazole derivatives.

[0251] When performing the blocking reaction (reacting with the blocking agent), a solvent may be added as needed. Suitable solvents for the blocking reaction are those that are not reactive with isocyanate groups. Examples include acetone, ketones such as methyl ethyl ketone, esters such as ethyl acetate, and solvents such as N-methyl-2-pyrrolidone (NMP).

[0252] Furthermore, as the blocking agent, hydroxycarboxylic acids having one or more hydroxyl groups and one or more carboxyl groups, such as hydroxypivalic acid and dimethylolpropionic acid, can also be used. In particular, a blocked polyisocyanate compound obtained by blocking the isocyanate group with the above-mentioned hydroxycarboxylic acid and then neutralizing the carboxyl group of the hydroxycarboxylic acid to impart water dispersibility can be suitably used.

[0253] If the curing agent (E) contains a blocked polyisocyanate compound (E4), the content of the blocked polyisocyanate compound (E4) is preferably in the range of 10 to 80% by mass, more preferably in the range of 15 to 70% by mass, and even more preferably in the range of 20 to 65% by mass, based on the total solid content of the curing agent (E), from the viewpoint of the storage stability of the resulting aqueous coating composition and the abrasion resistance and glass adhesion of the formed coating film.

[0254] Each of the above hardening agents (E) can be used individually or in combination of two or more types.

[0255] If the aqueous coating composition contains the curing agent (E), the content of the curing agent (E) is preferably in the range of 1 to 50% by mass, more preferably in the range of 5 to 45% by mass, and even more preferably in the range of 10 to 40% by mass, based on the amount of resin solids in the aqueous coating composition.

[0256] Other ingredients The aqueous coating composition of the present invention may further optionally contain acrylic urethane composite resin (AB) particle aqueous dispersion, resins other than acrylic resin (C), polyester resin (D), and curing agent (E), pigments, organic solvents, curing catalysts, dispersants, anti-settling agents, defoaming agents, thickeners, ultraviolet absorbers, light stabilizers, surface modifiers, etc.

[0257] Examples of resins other than the above-mentioned acrylic urethane composite resin (AB) particle aqueous dispersion, acrylic resin (C), polyester resin (D), and curing agent (E) include acrylic urethane composite resins other than the acrylic urethane composite resin (AB) particle aqueous dispersion, polyurethane resins, polyolefin resins, epoxy resins, etc.

[0258] Examples of the above-mentioned pigments include coloring pigments, extender pigments, and luminosity pigments. These pigments can be used individually or in combination of two or more types.

[0259] When the aqueous coating composition of the present invention contains the above-mentioned pigment, the amount of the pigment is preferably in the range of 0.1 to 200 parts by mass, more preferably in the range of 1 to 150 parts by mass, and even more preferably in the range of 3 to 120 parts by mass, based on 100 parts by mass of resin solids in the aqueous coating composition.

[0260] Examples of the above-mentioned coloring pigments include titanium dioxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, surene pigments, perylene pigments, dioxazine pigments, and diketopyrrolopyrrole pigments. Among these, titanium dioxide and carbon black can be preferably used.

[0261] When the aqueous coating composition of the present invention contains the above-mentioned coloring pigment, the amount of the coloring pigment is preferably in the range of 1 to 180 parts by mass, more preferably in the range of 5 to 150 parts by mass, and even more preferably in the range of 15 to 120 parts by mass, based on 100 parts by mass of resin solids in the aqueous coating composition.

[0262] Examples of the extender pigments include barium sulfate, talc, clay, kaolin, barium carbonate, calcium carbonate, silica, and alumina white. From the viewpoint of paint stability and finish, barium sulfate and talc can be suitably used as the extender pigment.

[0263] When the aqueous coating composition of the present invention contains the above-mentioned extender pigment, the amount of the extender pigment is preferably in the range of 1 to 180 parts by mass, more preferably in the range of 5 to 140 parts by mass, and even more preferably in the range of 10 to 120 parts by mass, based on 100 parts by mass of resin solids in the aqueous coating composition.

[0264] Examples of the luminous pigments include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, glass flakes, aluminum oxide, mica, aluminum oxide coated with titanium oxide and / or iron oxide, and mica coated with titanium oxide and / or iron oxide. Among these, aluminum pigments are preferred. Aluminum pigments include non-leafing aluminum pigments and leafing aluminum pigments, and either can be used.

[0265] The above-mentioned lustrous pigment is preferably in the form of flakes. Furthermore, suitable lustrous pigments have a longitudinal dimension in the range of 1 to 100 μm, particularly 5 to 40 μm, and a thickness in the range of 0.001 to 5 μm, particularly 0.01 to 2 μm.

[0266] When the aqueous coating composition of the present invention contains the above-mentioned luminous pigment, the amount of the luminous pigment is preferably in the range of 0.1 to 100 parts by mass, more preferably in the range of 1 to 50 parts by mass, and even more preferably in the range of 3 to 25 parts by mass, based on 100 parts by mass of resin solids in the aqueous coating composition.

[0267] Examples of the aforementioned organic solvents include ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as ethyl acetate, butyl acetate, methyl benzoate, ethyl ethoxypropionate, ethyl propionate, and methyl propionate; alcohol solvents such as isopropanol, n-butanol, isobutanol, and 2-ethylhexanol; ether solvents such as tetrahydrofuran, dioxane, and dimethoxyethane; glycol ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, and the like.

[0268] When using the aqueous coating composition of the present invention, water and / or an organic solvent, etc. can be added as necessary for dilution, and the composition can be applied by adjusting it to an appropriate viscosity.

[0269] The appropriate viscosity varies depending on the coating composition. For example, the viscosity after 1 minute at 60 rpm measured with a B-type viscometer at a temperature of 20°C (sometimes referred to as the "B60 value" in this specification) is preferably in the range of 100 to 3000 mPa·s, more preferably in the range of 300 to 2000 mPa·s, and even more preferably in the range of 500 to 1500 mPa·s from the viewpoint of the appearance of the formed coating film, etc. At this time, the viscometer to be used is "LVDV-I" (trade name, manufactured by BROOKFIELD, B-type viscometer).

[0270] Also, in the above, the coating solid content concentration of the aqueous coating composition of the present invention is usually preferably about 5 to 70% by mass, more preferably about 10 to 55% by mass.

[0271] Also, the gel fraction of the coating film formed from the aqueous coating composition of the present invention is preferably 85% or more, more preferably 87% or more, and even more preferably 90% or more from the viewpoints of the chipping resistance and glass adhesiveness of the formed coating film, etc.

[0272] In this specification, the gel fraction is measured by the following method.

[0273] First, the aqueous coating composition of the present invention is applied to a polypropylene plate for gel fraction measurement to a thickness of 30 μm, and heated at 80°C for 20 minutes to form a cured coating film. Next, the formed cured coating film is peeled off the polypropylene plate and placed in a 300-mesh stainless steel mesh container whose mass (W1) has been measured in advance, and the total mass (W2) of the cured coating film and the mesh container is measured. The mesh container containing the cured coating film is placed in an equal-mass mixed solvent of acetone and methanol heated to 50°C, and an extraction treatment is performed for 5 hours. After drying at 110°C for 60 minutes, the total mass (W3) of the remaining cured coating film and the mesh container is measured, and the insoluble coating film remaining rate (%) obtained according to the following formula is defined as the gel fraction. Gel fraction (%) = (W3 - W1) / (W2 - W1) × 100 The aqueous paint composition of the present invention may be either a one-component paint or a multi-component paint, but it is preferable to be a one-component paint from the viewpoint of having no paint mixing step and having excellent productivity, and simplifying the maintenance of painting machinery.

[0274] [Coating film formation method] The aqueous coating composition of the present invention can be used as an aqueous coating composition for forming a colored coating film on an object to be coated. In this case, the coating film can be formed according to Method I described below.

[0275] <Method I> Step (I-1): A step of applying an aqueous paint composition to the object to be coated to form an uncured colored coating film. A method for forming a coating film, comprising: step (I-2): a step of heat-curing the uncured colored coating film formed in step (I-1).

[0276] Examples of objects to be coated include the exterior and interior panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses; automobile parts; and the exterior panels of household electrical appliances such as mobile phones and audio equipment. Of these, the exterior and interior panels of automobile bodies and automobile parts are preferred.

[0277] The materials of these objects to be coated are not particularly limited. Examples include metallic materials such as iron, aluminum, brass, copper, tinplate, stainless steel, galvanized steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.) plated steel; plastic materials such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, and various types of FRP; inorganic materials such as glass, cement, and concrete; wood; and fibrous materials such as paper and cloth. Of these, metallic and plastic materials are preferred.

[0278] Furthermore, the surface to which the coating film is applied may be a metal surface such as the outer and inner panels of an automobile body, automobile parts, household electrical appliances, or metal substrates such as steel plates that make up these, which may have been subjected to surface treatments such as phosphate treatment, chromate treatment, or composite oxide treatment.

[0279] A coating film may be formed on an object that has been surface-treated or not. For example, the substrate (the object to be coated) may be surface-treated as needed, and then a primer coating film may be formed on it. If the object to be coated is an automobile body, for example, this primer coating film can be formed using a primer paint that is known and commonly used in automobile body painting.

[0280] For example, an electrodeposition paint, preferably a cationic electrodeposition paint, can be used as the primer paint for forming the undercoat film.

[0281] If the object to be coated has a primer coat applied, an intermediate coating may be formed on top of it. This intermediate coating can be formed, for example, if the object to be coated is an automobile body, using a known intermediate coating paint that is commonly used in automobile body painting. This intermediate coating may or may not be heat-cured.

[0282] The aqueous coating composition can be applied to the object to be coated by known methods, such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating, and electrostatic application may be performed during coating. Of these, air spray coating and rotary atomization coating are preferred. Furthermore, such coating methods can be carried out in one to several stages until the desired film thickness is obtained.

[0283] The amount of the above aqueous paint composition applied is preferably such that the cured film thickness of the formed colored coating film is 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 10 to 30 μm.

[0284] The heating can be carried out by known means, for example, drying furnaces such as hot air furnaces, electric furnaces, and infrared induction heating furnaces can be applied. The heating temperature is preferably in the range of 60 to 150°C, more preferably in the range of 70 to 120°C, and even more preferably in the range of 75 to 100°C. The heating time is not particularly limited, but is preferably in the range of 10 to 90 minutes, and more preferably in the range of 20 to 60 minutes.

[0285] [Method for forming multi-layer coatings] The aqueous coating composition of the present invention can be used for forming the intermediate coating and / or the base coat when forming a multi-layer coating consisting of an intermediate coating, a base coat, and a clear coat on an object to be coated, such as an automobile body, using a 3-coat 1-bake method.

[0286] When the aqueous coating composition of the present invention is used for forming the intermediate coating film described above, a multi-layer coating film can be formed according to Method II below.

[0287] <Method II> Step (II-1): A step of applying the aqueous coating composition of the present invention onto the object to be coated to form an uncured intermediate coating film. Step (II-2): A step of applying a base coat paint composition onto the uncured intermediate coat film formed in the step (II-1) to form an uncured base coat film. Step (II-3): A step of applying a clear coat paint composition onto the uncured base coat film formed in the step (II-2) to form an uncured clear coat film. Step (II-4): A step of heat-curing the uncured intermediate coat film formed in the step (II-1), the uncured base coat film formed in the step (II-2), and the uncured clear coat film formed in the step (II-3) at once. A method for forming a multilayer coating film including this step.

[0288] As the object to be coated, the objects exemplified in the method I can be used.

[0289] Further, as the surface of the object to which the coating film is applied, a metal surface such as an outer panel part and an inner panel part of an automobile body, automobile parts, household electric appliances, and a metal base material such as a steel sheet constituting these may be subjected to surface treatment such as phosphate treatment, chromate treatment, or composite oxide treatment.

[0290] A coating film may be further formed on an object that may or may not be subjected to surface treatment. For example, the object to be coated as the base material may be subjected to surface treatment as necessary, and an undercoat film may be formed thereon. The undercoat film can be formed using, for example, a paint for undercoat that is known per se and is usually used in the coating of an automobile body when the object to be coated is an automobile body.

[0291] As the undercoat paint for forming the undercoat film, for example, an electrodeposition paint, preferably a cationic electrodeposition paint can be used.

[0292] The aqueous coating composition can be applied to the object to be coated by known methods, such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating, and electrostatic application may be performed during coating. Of these, air spray coating and rotary atomization coating are preferred. Furthermore, such coating methods can be carried out in one to several stages until the desired film thickness is obtained.

[0293] The amount of the above-mentioned aqueous coating composition applied is preferably such that the cured film thickness of the intermediate coating formed is 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 10 to 30 μm.

[0294] As the base coat coating composition, a base resin such as an acrylic resin, polyester resin, alkyd resin, urethane resin, or epoxy resin having crosslinkable functional groups such as carboxyl groups or hydroxyl groups, and a crosslinking agent such as an amino resin such as a melamine resin or urea resin, or a polyisocyanate compound which may be blocked, can be used in a coating made together with a pigment, a thickener, and other optional components.

[0295] The application method for the above-mentioned base coat paint composition is not particularly limited, but a wet coating can be formed by application methods such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating. Electrostatic application may be performed as needed in these application methods. Of these, air spray coating or rotary atomization coating is particularly preferred. The amount of base coat paint composition applied is usually preferably such that the cured film thickness is 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 10 to 30 μm.

[0296] Any thermosetting clear coating composition known for use in painting automobile bodies and the like can be used as the clear coat coating composition. Examples of such thermosetting clear coating compositions include organic solvent-type thermosetting coating compositions containing a base resin having crosslinkable functional groups and a curing agent, aqueous thermosetting coating compositions, and powder thermosetting coating compositions. Among these, organic solvent-type thermosetting coating compositions containing a base resin having crosslinkable functional groups and a crosslinking agent are preferred from the viewpoint of the finished appearance of the multi-layer coating film that is formed.

[0297] Examples of crosslinkable functional groups in the above-mentioned base resin include carboxyl groups, hydroxyl groups, epoxy groups, and alkoxysilyl groups. Examples of base resin types include acrylic resins, polyester resins, alkyd resins, urethane resins, epoxy resins, and fluororesins. Examples of curing agents include polyisocyanate compounds, blocked polyisocyanate compounds, melamine resins, urea resins, carboxyl group-containing compounds, carboxyl group-containing resins, epoxy group-containing resins, and epoxy group-containing compounds.

[0298] Preferred combinations of base resin / curing agent for the above clear coat coating composition include hydroxyl group-containing resin / polyisocyanate compound, carboxyl group-containing resin / epoxy group-containing resin, hydroxyl group-containing resin / blocked polyisocyanate compound, and hydroxyl group-containing resin / melamine resin, with hydroxyl group-containing resin / polyisocyanate compound being more preferred.

[0299] Furthermore, the above-mentioned clear coat paint composition may be a one-component paint or a multi-component paint such as a two-component urethane resin paint.

[0300] Furthermore, the above clear coat paint composition may contain, if necessary, coloring pigments, luminescence pigments, dyes, etc., to an extent that does not impair transparency, and may also contain, as appropriate, extender pigments, ultraviolet absorbers, light stabilizers, defoamers, thickeners, rust inhibitors, surface modifiers, etc.

[0301] The method of applying the clear coat coating composition is not particularly limited, but a wet coating can be formed by coating methods such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating. Electrostatic application may be performed as needed in these coating methods. Of these, air spray coating or rotary atomization coating is particularly preferred. The amount of clear coating composition applied is usually preferably an amount that results in a cured film thickness of 10 to 70 μm, and more preferably an amount that results in a cured film thickness of 20 to 50 μm.

[0302] Furthermore, when performing air spray painting, airless spray painting, or rotary atomization painting, it is preferable to adjust the viscosity of the clear coating composition using an organic solvent or other solvent to a viscosity range suitable for the painting method, typically a viscosity range of about 15 to 60 seconds at 20°C, and particularly about 20 to 50 seconds, using a Ford Cup No. 4 viscometer.

[0303] The heating can be carried out by known means, for example, drying furnaces such as hot air furnaces, electric furnaces, and infrared induction heating furnaces can be applied. The heating temperature is preferably in the range of 60 to 150°C, more preferably in the range of 70 to 120°C, and even more preferably in the range of 75 to 100°C. The heating time is not particularly limited, but is preferably in the range of 10 to 90 minutes, and more preferably in the range of 20 to 60 minutes.

[0304] Furthermore, when the aqueous coating composition of the present invention is used for forming the base coat coating film described above, a multi-layer coating film can be formed according to Method III below.

[0305] <Method III> Step (III-1): A step of applying an intermediate coating paint composition to the object to be coated to form an uncured intermediate coating film. Step (III-2): A step of applying the aqueous paint composition of the present invention onto the uncured intermediate coating film formed in step (III-1) to form an uncured base coat film. Step (III-3): A step of applying a clear coat paint composition onto the uncured base coat film formed in step (III-2) to form an uncured clear coat film. A method for forming a multilayer coating, comprising: step (III-4): a step of simultaneously heating and curing the uncured intermediate coating film formed in step (III-1), the uncured base coat coating film formed in step (III-2), and the uncured clear coat coating film formed in step (III-3).

[0306] As the object to be coated, the object to be coated as exemplified in Method I above can be used.

[0307] Furthermore, the surface to which the coating film is applied may be a metal surface such as the outer and inner panels of an automobile body, automobile parts, household electrical appliances, or metal substrates such as steel plates that make up these, which may have been subjected to surface treatments such as phosphate treatment, chromate treatment, or composite oxide treatment.

[0308] A coating film may be formed on an object that has been surface-treated or not. For example, the substrate (the object to be coated) may be surface-treated as needed, and then a primer coating film may be formed on it. If the object to be coated is an automobile body, for example, this primer coating film can be formed using a primer paint that is known and commonly used in automobile body painting.

[0309] For example, an electrodeposition paint, preferably a cationic electrodeposition paint, can be used as the primer paint for forming the undercoat film.

[0310] As the aforementioned intermediate coating paint composition, a base resin such as an acrylic resin, polyester resin, alkyd resin, urethane resin, or epoxy resin having crosslinkable functional groups such as carboxyl groups or hydroxyl groups, and a crosslinking agent such as an amino resin such as a melamine resin or urea resin, or a polyisocyanate compound which may be blocked, can be used as a paint, together with a pigment, a thickener, and other optional components.

[0311] The application method for the above-mentioned intermediate coating composition is not particularly limited, but a wet coating can be formed by application methods such as air spray coating, airless spray coating, rotary atomization coating, and curtain coat coating. Electrostatic application may be performed as needed in these application methods. Of these, air spray coating or rotary atomization coating is particularly preferred. The amount of the intermediate coating composition applied is usually preferably such that the cured film thickness is 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 10 to 30 μm.

[0312] The aqueous coating composition can be applied to the object to be coated by known methods, such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating, and electrostatic application may be performed during coating. Of these, air spray coating and rotary atomization coating are preferred. Furthermore, such coating methods can be carried out in one to several stages until the desired film thickness is obtained.

[0313] The amount of the above-mentioned aqueous coating composition applied is preferably such that the cured film thickness of the formed base coat is 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 10 to 30 μm.

[0314] As the clear coat coating composition, the clear coat coating composition exemplified in Method II can be used.

[0315] The method of applying the clear coat coating composition is not particularly limited, but a wet coating can be formed by coating methods such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating. Electrostatic application may be performed as needed in these coating methods. Of these, air spray coating or rotary atomization coating is particularly preferred. The amount of clear coating composition applied is usually preferably an amount that results in a cured film thickness of 10 to 70 μm, and more preferably an amount that results in a cured film thickness of 20 to 50 μm.

[0316] Furthermore, when performing air spray painting, airless spray painting, or rotary atomization painting, it is preferable to adjust the viscosity of the clear coating composition using an organic solvent or other solvent to a viscosity range suitable for the painting method, typically a viscosity range of about 15 to 60 seconds at 20°C, and particularly about 20 to 50 seconds, using a Ford Cup No. 4 viscometer.

[0317] The heating can be carried out by known means, for example, drying furnaces such as hot air furnaces, electric furnaces, and infrared induction heating furnaces can be applied. The heating temperature is preferably in the range of 60 to 150°C, more preferably in the range of 70 to 120°C, and even more preferably in the range of 75 to 100°C. The heating time is not particularly limited, but is preferably in the range of 10 to 90 minutes, and more preferably in the range of 20 to 60 minutes.

[0318] Furthermore, when the aqueous coating composition of the present invention is used for forming the intermediate coating film and the base coat coating film as described above, a multi-layer coating film can be formed according to Method IV below. The aqueous paint composition of the present invention used for forming the intermediate coating film and the aqueous paint composition of the present invention used for forming the base coat film may be the same or different.

[0319] <Method IV> Step (IV-1): A step of applying the aqueous coating composition of the present invention onto the object to be coated to form an uncured intermediate coating film. Step (IV-2): A step of applying the aqueous paint composition of the present invention onto the uncured intermediate coating film formed in step (IV-1) to form an uncured base coat film. Step (IV-3): A step of applying a clear coat paint composition onto the uncured base coat film formed in step (IV-2) to form an uncured clear coat film. A method for forming a multilayer coating, comprising: step (IV-4): a step of simultaneously heating and curing the uncured intermediate coating film formed in step (IV-1), the uncured base coat coating film formed in step (IV-2), and the uncured clear coat coating film formed in step (IV-3).

[0320] As the object to be coated, the object to be coated as exemplified in Method I above can be used.

[0321] Furthermore, the surface to which the coating film is applied may be a metal surface such as the outer and inner panels of an automobile body, automobile parts, household electrical appliances, or metal substrates such as steel plates that make up these, which may have been subjected to surface treatments such as phosphate treatment, chromate treatment, or composite oxide treatment.

[0322] A coating film may be formed on an object that has been surface-treated or not. For example, the substrate (the object to be coated) may be surface-treated as needed, and then a primer coating film may be formed on it. If the object to be coated is an automobile body, for example, this primer coating film can be formed using a primer paint that is known and commonly used in automobile body painting.

[0323] For example, an electrodeposition paint, preferably a cationic electrodeposition paint, can be used as the primer paint for forming the undercoat film.

[0324] The aqueous coating composition used for forming the intermediate coating film can be applied to the object to be coated by known methods, such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating, and electrostatic application may be performed during coating. Of these, air spray coating and rotary atomization coating are preferred. Furthermore, such coating methods can be carried out in one to several stages until the desired film thickness is obtained.

[0325] The amount of the aqueous paint composition used for forming the intermediate coating film described above is preferably such that the cured film thickness of the intermediate coating film formed is 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 10 to 30 μm.

[0326] The aqueous paint composition used for forming the base coat film can be applied to the object to be coated by known methods, such as air spray painting, airless spray painting, rotary atomization painting, and curtain coat painting, and electrostatic application may be performed during painting. Of these, air spray painting and rotary atomization painting are preferred. Furthermore, such painting methods can be carried out in one to several stages until the desired film thickness is obtained.

[0327] The amount of aqueous paint composition used for forming the base coat film described above is preferably such that the cured film thickness of the base coat film formed is 5 to 40 μm, more preferably 7 to 35 μm, and even more preferably 10 to 30 μm.

[0328] As the clear coat coating composition, the clear coat coating composition exemplified in Method II can be used.

[0329] The method of applying the clear coat coating composition is not particularly limited, but a wet coating can be formed by coating methods such as air spray coating, airless spray coating, rotary atomization coating, and curtain coating. Electrostatic application may be performed as needed in these coating methods. Of these, air spray coating or rotary atomization coating is particularly preferred. The amount of clear coating composition applied is usually preferably an amount that results in a cured film thickness of 10 to 70 μm, and more preferably an amount that results in a cured film thickness of 20 to 50 μm.

[0330] Furthermore, when performing air spray painting, airless spray painting, or rotary atomization painting, it is preferable to adjust the viscosity of the clear coating composition using an organic solvent or other solvent to a viscosity range suitable for the painting method, typically a viscosity range of about 15 to 60 seconds at 20°C, and particularly about 20 to 50 seconds, using a Ford Cup No. 4 viscometer.

[0331] The heating can be carried out by known means, for example, drying furnaces such as hot air furnaces, electric furnaces, and infrared induction heating furnaces can be applied. The heating temperature is preferably in the range of 60 to 150°C, more preferably in the range of 70 to 120°C, and even more preferably in the range of 75 to 100°C. The heating time is not particularly limited, but is preferably in the range of 10 to 90 minutes, and more preferably in the range of 20 to 60 minutes. [Examples]

[0332] The present invention will be described in more detail below with reference to manufacturing examples, examples, and comparative examples. However, the present invention is not limited thereto. In each example, "parts" and "%" are based on mass unless otherwise specified. Furthermore, the film thickness of the coating is based on the cured coating.

[0333] Preparation of compound (a1) having a secondary amino group and an alkoxysilyl group Manufacturing Example 1 In a reaction vessel equipped with a thermometer, thermostat, stirrer, and reflux condenser, 55.89 parts of n-butyl acrylate and 0.01 parts of dibutylhydroxytoluene were charged and stirred under an airflow, and the mixture was heated to 50°C. Next, 44.1 parts of "KBM-602" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane) were added dropwise over 2 hours to the reaction vessel maintained at the same temperature. After the dropwise addition was complete, 1.0 part of butyl acetate was charged and the mixture was aged for 2 hours. Next, the mixture was drained while being filtered through a 100-mesh nylon cloth, and then allowed to stand in a constant temperature room at 50°C for 1 week to obtain compound (a1-1) containing a secondary amino group and an alkoxysilyl group.

[0334] Manufacturing Examples 2-12 Compounds (a1-2) to (a1-12) having a secondary amino group and an alkoxysilyl group were obtained in the same manner as in Production Example 1, except that the formulation composition was as shown in Table 1 below.

[0335] [Table 1]

[0336] [Table 2]

[0337] The components listed in the table are as follows: (Note 1) "KBM-603": Product name, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, (Note 2) "KBM-903": Product name, manufactured by Shin-Etsu Chemical Co., Ltd., 3-aminopropyltrimethoxysilane.

[0338] Manufacturing of acrylic urethane composite resin (AB') particle aqueous dispersions Example 1 In a reaction vessel equipped with a thermometer, thermostat, stirrer and reflux condenser, 41.0 parts n-butyl acrylate, 2.49 parts allyl methacrylate, 16.1 parts "ETERNACOLL UH-200" (trade name, manufactured by Ube Industries, Ltd., polycarbonate diol with 1,6-hexanediol as the main backbone, molecular weight 2000), 9.7 parts "PTMG2000" (trade name, manufactured by Mitsubishi Chemical Corporation, polytetramethylene ether glycol, molecular weight 2000), 0.29 parts 1,4-cyclohexanedimethanol, 4.7 parts dimethylolpropionic acid, 0.02 parts p-methoxyphenol (polymerization inhibitor for unsaturated groups), and "Neostan 0.004 parts of "U-600" (product name, manufactured by Nitto Kasei Co., Ltd., bismuth-based catalyst) were charged, and the mixture was heated to 80°C while stirring in an air stream. Then, 2.1 parts of isophorone diisocyanate and 12.9 parts of dicyclohexylmethane-4,4'-diisocyanate were added dropwise over 30 minutes. The mixture was then heated to 100°C and reacted until the free isocyanate group content was 2.0% or less to obtain a diluted solution of acrylic monomer for the urethane prepolymer.

[0339] Next, the diluted acrylic monomer solution of the urethane prepolymer obtained above was cooled to 60°C, and 2.84 parts of compound (a1-1) containing secondary amino groups and alkoxysilyl groups obtained in Production Example 1 were added dropwise over 10 minutes. After the addition was complete, the mixture was allowed to mature for 20 minutes. Then, the temperature was raised to 100°C, 4.97 parts of 2-hydroxyethyl methacrylate were added, and the mixture was reacted until the free isocyanate group content was 0.1% or less, and then cooled to room temperature.

[0340] Next, 2.7 parts of triethylamine and 117.8 parts of deionized water were added dropwise over 60 minutes.

[0341] Next, the mixture was heated to 70°C while stirring in a nitrogen atmosphere. A polymerization initiator solution, prepared by dissolving 0.15 parts of "VA-057" (product name, manufactured by Wako Pure Chemical Industries, Ltd., polymerization initiator, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide]) in 9.2 parts of deionized water, was added dropwise over 30 minutes. The mixture was then stirred for 3 hours to carry out the polymerization reaction of the acrylic resin components (polymerizable unsaturated groups). During this time, the temperature was controlled as needed.

[0342] The mixture was then cooled to room temperature, and the concentration was adjusted with deionized water to obtain an aqueous dispersion of acrylic urethane composite resin (AB'-1) particles having a core-shell structure consisting of a shell made of urethane resin and a core made of acrylic resin, with a solid content concentration of 40%, an acid value of 20 mg KOH / g, and an average particle size of 140 nm (measured at 20°C after dilution with deionized water using a dynamic light scattering particle size distribution analyzer "ELSZ-2000" (product name, manufactured by Otsuka Electronics Co., Ltd.)).

[0343] Examples 2-40, Comparative Examples 1-2 In Example 1, an aqueous dispersion of acrylic urethane composite resin (AB'-2) to (AB'-40) and (AB'-44) to (AB'-45) particles was obtained in the same manner as in Example 1, except that the compound composition was as shown in Table 2 below.

[0344] Example 41 In a reaction vessel equipped with a thermometer, thermostat, stirrer and reflux condenser, the following were added: 40.5 parts n-butyl acrylate, 2.46 parts allyl methacrylate, 15.4 parts "ETERNACOLL UH-200" (trade name, manufactured by Ube Industries, Ltd., polycarbonate diol with 1,6-hexanediol as the main backbone, molecular weight 2000), 9.0 parts "PTMG2000" (trade name, manufactured by Mitsubishi Chemical Corporation, polytetramethylene ether glycol, molecular weight 2000), 0.23 parts 1,4-cyclohexanedimethanol, 1.03 parts "Bremmer GLM" (trade name, manufactured by NOF Corporation, glycerin monomethacrylate), 4.7 parts dimethylolpropionic acid, 0.02 parts p-methoxyphenol (polymerization inhibitor for unsaturated groups), and "Neostan 0.004 parts of "U-600" (product name, manufactured by Nitto Kasei Co., Ltd., bismuth-based catalyst) were charged, and the mixture was heated to 80°C while stirring in an air stream. Then, 3.4 parts of isophorone diisocyanate and 12.6 parts of dicyclohexylmethane-4,4'-diisocyanate were added dropwise over 30 minutes. The mixture was then heated to 100°C and reacted until the content of retained free isocyanate groups was 2.0% or less to obtain a diluted solution of acrylic monomer for the urethane prepolymer.

[0345] Next, the diluted acrylic monomer solution of the urethane prepolymer obtained above was cooled to 60°C, and 2.79 parts of compound (a1-1) containing a secondary amino group and an alkoxysilyl group obtained in Production Example 1 were added dropwise over 10 minutes. After the addition was complete, the mixture was allowed to mature for 20 minutes and then cooled to room temperature.

[0346] Next, 4.91 parts of 2-hydroxyethyl methacrylate were added, and 2.7 parts of triethylamine and 117.8 parts of deionized water were added dropwise over 60 minutes. After emulsification, 3.6 parts of a 5% ethylenediamine aqueous solution were added dropwise over 15 minutes to carry out the chain extension reaction.

[0347] Next, the mixture was heated to 70°C while stirring in a nitrogen atmosphere. A polymerization initiator solution, prepared by dissolving 0.15 parts of "VA-057" (product name, manufactured by Wako Pure Chemical Industries, Ltd., polymerization initiator, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide]) in 9.2 parts of deionized water, was added dropwise over 30 minutes. The mixture was then stirred for 3 hours to carry out the polymerization reaction of the acrylic resin components (polymerizable unsaturated groups). During this time, the temperature was controlled as needed.

[0348] The mixture was then cooled to room temperature, and the concentration was adjusted with deionized water to obtain an aqueous dispersion of acrylic urethane composite resin (AB'-41) particles having a core-shell structure consisting of a shell made of urethane resin and a core made of acrylic resin. The dispersion had a solid content of 40%, an acid value of 20 mg KOH / g, and an average particle size of 120 nm (measured at 20°C using a dynamic light scattering particle size distribution analyzer "ELSZ-2000" (product name, manufactured by Otsuka Electronics Co., Ltd.), diluted with deionized water). Examples 42-43 In Example 41, an aqueous dispersion of acrylic urethane composite resin (AB'-42) to (AB'-43) particles was obtained in the same manner as in Example 41, except that the compound composition was as shown in Table 2 below.

[0349] [Table 3]

[0350] [Table 4]

[0351] [Table 5]

[0352] [Table 6]

[0353] [Table 7]

[0354] [Table 8]

[0355] [Table 9]

[0356] [Table 10]

[0357] The components listed in the table are as follows: (Note 3) "ETERNACOLL UM-90(3 / 1)": Product name, manufactured by Ube Industries, Ltd., a polycarbonate diol with 1,6-hexanediol and 1,4-cyclohexanedimethanol as the main backbone, molecular weight 900. (Note 4) "ETERNACOLL UC-100": Product name, manufactured by Ube Industries, Ltd., a polycarbonate diol with 1,4-cyclohexanedimethanol as the main backbone, molecular weight 1000. (Note 5) "ETERNACOLL UP-200": Product name, manufactured by Ube Industries, Ltd., polycarbonate diol, molecular weight 2000. (Note 6) "Kuraray Polyol C-3090": Product name, manufactured by Kuraray Co., Ltd., polycarbonate diol, molecular weight 3000, (Note 7) "PTMG3000": Product name, manufactured by Mitsubishi Chemical Corporation, polytetramethylene ether glycol, molecular weight 3000 (Note 8) "PTMG1000": Product name, manufactured by Mitsubishi Chemical Corporation, polytetramethylene ether glycol, molecular weight 1000. (Note 9) "Sannix PP-2000": Product name, manufactured by Sanyo Chemical Industries, Ltd., polypropylene glycol, molecular weight 2000) (Note 10) "Bremmer GLM": Product name, manufactured by NOF Corporation, glycerin monomethacrylate, (Note 11) "Epoxy Ester 70PA": Trade name, manufactured by Kyoeisha, acrylic acid adduct of propylene glycol diglycidyl ether, (Note 12) "Epoxy Ester 200PA": Trade name, manufactured by Kyoeisha, an acrylic acid adduct of tripropylene glycol diglycidyl ether.

[0358] Manufacturing of acrylic resin (C) Manufacturing Example 13 In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, and dropper, 120 parts of deionized water and 0.8 parts of "Adekaria Soap SR-1025" (product name, manufactured by ADEKA, emulsifier, 25% active ingredient) were charged, stirred and mixed under a nitrogen atmosphere, and the temperature was raised to 80°C.

[0359] Next, 5% of the total amount of the monomer emulsion for the core portion and 2.5 parts of a 6% ammonium persulfate aqueous solution were introduced into the reaction vessel and maintained at 80°C for 15 minutes. Then, the remaining monomer emulsion for the core portion was added dropwise over 3 hours to the reaction vessel maintained at the same temperature, and the mixture was allowed to mature for 1 hour after the dropwise addition was complete. Next, the monomer emulsion for the shell portion was added dropwise over 1 hour and matured for 1 hour. Then, 3.8 parts of a 5% 2-(dimethylamino)ethanol aqueous solution was gradually added to the reaction vessel while cooling to 30°C, and the mixture was drained while filtering through a 100-mesh nylon cloth to obtain an acrylic resin (C-1) particle dispersion with an average particle size of 100 nm and a solid content of 30%. The obtained acrylic resin particles had an acid value of 17.2 mg KOH / g and a hydroxyl value of 27.2 mg KOH / g.

[0360] A monomer emulsion for the core was obtained by mixing and stirring 54 parts of deionized water, 3.1 parts of "Adekaria Soap SR-1025", 1 part of allyl methacrylate, 10 parts of styrene, 35 parts of n-butyl acrylate, 10 parts of methyl methacrylate, 20 parts of ethyl acrylate, and 1 part of 2-hydroxyethyl methacrylate.

[0361] A monomer emulsion for the shell was obtained by mixing and stirring 50 parts of deionized water, 1.8 parts of "Adekaria Soap SR-1025", 0.04 parts of ammonium persulfate, 5.3 parts of 2-hydroxyethyl acrylate, 2.6 parts of methacrylic acid, 8 parts of ethyl acrylate, and 7.1 parts of methyl methacrylate.

[0362] Manufacturing of polyester resin (D) Manufacturing Example 14 In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, and water separator, 126 parts trimesic acid, 1365 parts PTMG650 (trade name, manufactured by Mitsubishi Chemical Corporation, polytetramethylene ether glycol, molecular weight 650), and 37 parts glycerin were charged. The temperature was raised between 160°C and 230°C over 3 hours, and then the condensation reaction was carried out at 230°C until the final acid value reached 3 mg KOH / g. Next, to add carboxyl groups to the obtained condensation reaction product, 77 parts trimellitic anhydride were added, and the reaction was carried out at 170°C for 30 minutes. Then, 0.5 equivalents of 2-(dimethylamino)ethanol were added relative to the acid groups, and the mixture was further diluted with 2-ethyl-1-hexanol to obtain a polyester resin (D-1) solution with a solid content of 70%. The obtained polyester resin had an acid value of 32 mgKOH / g, a hydroxyl value of 117 mgKOH / g, a solids content of 70%, and a number-average molecular weight of 1200.

[0363] Production of blocked polyisocyanate compounds (E4) Manufacturing Example 15 In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, dropping device, and simple solvent removal trap, 360 parts of "Sumijoule N-3300," 60 parts of "Uniox M-550" (manufactured by NOF Corporation, polyethylene glycol monomethyl ether, average molecular weight approximately 550), and 0.2 parts of 2,6-di-tert-butyl-4-methylphenol were charged and thoroughly mixed, and heated at 130°C for 3 hours under a nitrogen stream. Next, 110 parts of ethyl acetate and 252 parts of diisopropyl malonate were charged, and while stirring under a nitrogen stream, 3 parts of a 28% methanol solution of sodium methoxide were added, and the mixture was stirred at 65°C for 8 hours. The amount of isocyanate in the resulting resin solution was 0.12 mol / kg. 683 parts of 4-methyl-2-pentanol were added to this, and the solvent was removed by distillation under reduced pressure for 3 hours while maintaining the system temperature at 80-85°C to obtain 1010 parts of the activated methylene-type blocked polyisocyanate compound (E4-1) solution. The simple solvent removal trap contained 95 parts of isopropanol. The solid content concentration of the obtained activated methylene-type blocked polyisocyanate compound (E4-1) solution was approximately 60%.

[0364] Production of phosphate group-containing dispersion resin (R) Manufacturing Example 16 A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, and dropping device was filled with a mixed solvent of 27.5 parts methoxypropanol and 27.5 parts isobutanol, heated to 110°C, and 121.5 parts of a mixture consisting of 25 parts styrene, 27.5 parts n-butyl methacrylate, 20 parts isostearyl acrylate (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd., branched higher alkyl acrylate), 7.5 parts 4-hydroxybutyl acrylate, 15 parts phosphate-containing polymerizable unsaturated monomer (Note 1), 12.5 parts 2-methacryloyloxyethyl acid phosphate, 10 parts isobutanol, and 4 parts t-butyl peroxyoctanoate were added to the mixed solvent over 4 hours. A mixture consisting of 0.5 parts t-butyl peroxyoctanoate and 20 parts isopropanol was then added dropwise over 1 hour. After that, the mixture was stirred and aged for 1 hour to obtain a phosphate-containing dispersion resin (R-1) solution with a solid content of 50%. The acid value due to the phosphate group of this resin was 83 mgKOH / g, the hydroxyl value was 29 mgKOH / g, and the weight-average molecular weight was 10,000. (Note 1) Phosphate group-containing polymerizable unsaturated monomer: In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, and dropping device, 57.5 parts monobutyl phosphate and 41 parts isobutanol were added. After raising the temperature to 90°C, 42.5 parts glycidyl methacrylate were added dropwise over 2 hours, and the mixture was stirred and aged for another hour. Then, 59 parts isopropanol was added to obtain a phosphate group-containing polymerizable unsaturated monomer solution with a solid content of 50%. The acid value of the obtained monomer due to the phosphate group was 285 mgKOH / g.

[0365] Manufacturing of pigment dispersion (P) Manufacturing Example 17 28.6 parts (20 parts solids) of the polyester resin (D-1) solution obtained in Production Example 14, 90 parts of "JR-806" (product name, manufactured by Teika Co., Ltd., rutile-type titanium dioxide), 30 parts of "Variace B-35" (product name, manufactured by Sakai Chemical Industry Co., Ltd., barium sulfate powder), 0.8 parts of "Carbon MA100" (product name, manufactured by Mitsubishi Chemical Corporation, carbon black), and 10 parts of deionized water were mixed and the pH was adjusted to 8.0 with 2-(dimethylamino)ethanol. Next, the resulting mixture was placed in a wide-mouthed glass bottle, glass beads with a diameter of approximately 1.3 mm were added as a dispersion medium, the bottle was sealed, and the mixture was dispersed in a paint shaker for 30 minutes to obtain pigment dispersion (P-1).

[0366] Manufacturing Example 18 In a container equipped with a stirring device, 66.7 parts (20 parts solids) of the acrylic resin (C-1) particle dispersion obtained in Production Example 13, 10 parts of "Carbon MA-100" (product name, manufactured by Mitsubishi Chemical Corporation, carbon black), and 50 parts of deionized water were placed and mixed uniformly, and the pH was adjusted to 7.5 with 2-(dimethylamino)ethanol. Next, the resulting mixed solution was placed in a wide-mouthed glass bottle, glass beads with a diameter of approximately 1.3 mm were added as a dispersion medium, and the bottle was sealed. The mixture was then dispersed in a paint shaker for 4 hours to obtain pigment dispersion (P-2).

[0367] Preparation of aqueous paint compositions Example 44 112.5 parts (45 parts solids) of acrylic urethane composite resin (AB'-1) particle aqueous dispersion obtained in Example 1, 50 parts (15 parts solids) of acrylic resin (C-1) particle dispersion obtained in Production Example 13, 25 parts (10 parts solids) of "Carbodilite SV02" (product name, manufactured by Nisshinbo Inc., carbodiimide compound, 40% solids, carbodiimide equivalent per solids 429), 6.25 parts (5 parts solids) of "Cymel 325" (product name, manufactured by Ornex Japan Inc., melamine resin, solids concentration 80%), and the active obtained in Production Example 15 8.3 parts (5 parts solids) of a methylene-type blocked polyisocyanate compound (E4-1) solution and 159.4 parts (20 parts resin solids) of the pigment dispersion (P-1) obtained in Production Example 17 were uniformly mixed. Further, "UH-752" (trade name, manufactured by ADEKA, thickener, solid content concentration 28%), 2-(dimethylamino)ethanol, and deionized water were added to obtain aqueous paint composition No. 1 with a pH of 8.0, a solid content concentration of 48%, and a viscosity of 800 mPa·s after 1 minute at 60 rpm measured with a B-type viscometer at a temperature of 20°C.

[0368] Examples 45-92 and Comparative Examples 3-4 Water-based paint compositions No. 2 to 49 and No. 99 to 100 were obtained in the same manner as water-based paint composition No. 1 of Example 44, except that the paint composition was as shown in Table 3 below.

[0369] Example 93 87.5 parts (35 parts solids) of acrylic urethane composite resin (AB'-1) particle aqueous dispersion obtained in Example 1, 76.6 parts (23 parts solids) of acrylic resin (C-1) particle dispersion obtained in Production Example 13, 12.4 parts (5 parts solids) of "Carbodilite SV02" (trade name, manufactured by Nisshinbo Inc., carbodiimide compound, 40% solids, carbodiimide equivalent per solids 429), 6.25 parts (5 parts solids) of "Cymel 325" (trade name, manufactured by Ornex Japan Inc., melamine resin, solids concentration 80%), and activated methylene-type blocked polyisocyanate obtained in Production Example 15. 16.7 parts of compound (E4-1) solution (10 parts solids), 126.7 parts of pigment dispersion (P-2) obtained in Production Example 18 (20 parts resin solids), and 4 parts of phosphate-containing acrylic resin (R-1) obtained in Production Example 16 (2 parts solids) were uniformly mixed. Further, "UH-752" (trade name, manufactured by ADEKA, thickener, solids concentration 28%), 2-(dimethylamino)ethanol, and deionized water were added to obtain aqueous paint composition No. 50 with a pH of 8.0, a solids concentration of 25%, and a viscosity of 800 mPa·s after 1 minute at 60 rpm measured with a B-type viscometer at a temperature of 20°C.

[0370] Examples 94-141 and Comparative Examples 5-6 Water-based paint compositions No. 51 to 98 and No. 101 to 102 were obtained in the same manner as water-based paint composition No. 50 of Example 93, except that the paint composition was as shown in Table 3 below.

[0371] Gel fraction Each aqueous coating composition obtained in Examples 44-141 and Comparative Examples 3-6 was applied to a polypropylene plate for gel fraction measurement to a thickness of 30 μm, heated at 80°C for 20 minutes to form a cured coating film. Next, the formed cured coating film was peeled off the polypropylene plate and placed in a 300-mesh stainless steel mesh container whose mass (W1) had been measured in advance, and the total mass (W2) of the cured coating film and the mesh container was measured. The mesh container containing the cured coating film was placed in an equal-mass mixed solvent of acetone and methanol heated to 50°C and subjected to an extraction treatment for 5 hours. After drying at 110°C for 60 minutes, the total mass (W3) of the remaining cured coating film and the mesh container was measured, and the insoluble coating film retention rate (%) obtained according to the following formula was defined as the gel fraction. Gel fraction (%) = (W3 - W1) / (W2 - W1) × 100 The results of the gel fraction measurement are shown in Table 3.

[0372] Storage stability test The storage stability of each aqueous paint composition obtained in Examples 44-141 and Comparative Examples 3-6 was evaluated based on the viscosity measured at 60 rpm for 1 minute using an "LVDV-I" (trade name, manufactured by Brookfield, a B-type viscometer), comparing the viscosity immediately after production with the percentage change in viscosity after standing at 40°C for 10 days. Viscosity change rate (%) = |(Viscosity after standing at 40°C for 10 days / Viscosity immediately after manufacturing) - 1| × 100 ◎ and ○ indicate a passing grade. The evaluation results are shown in Table 3. ◎: Viscosity change rate is less than 50%. ○: Viscosity change rate is 50% or more, but less than 100%. ×: Viscosity change rate is 100% or more.

[0373] Abrasion resistance test A cold-rolled steel sheet treated with zinc phosphate conversion coating was electrodeposited with "Elecron GT-10" (product name, manufactured by Kansai Paint Co., Ltd., cationic electrodeposition coating) to a dry film thickness of 20 μm, and the electrodeposited coating was cured by heating at 170°C for 30 minutes to prepare a substrate for abrasion resistance testing. On this substrate for abrasion resistance testing, each aqueous coating composition obtained in Examples 44 to 141 and Comparative Examples 3 to 6 was electrostatically coated using a rotary atomizing electrostatic coating machine to a dry film thickness of 15 μm, forming an uncured coating film. After standing for 3 minutes, preheating was performed at 80°C for 3 minutes, and then heating was performed at 80°C for 20 minutes to prepare a coated plate for abrasion resistance testing.

[0374] The painted plates for abrasion resistance testing obtained above were weighed before the abrasion test. Then, they were mounted on a "5130 ABRASER" (product name, manufactured by Toyo Seiki Co., Ltd., Taber-type abrasion tester) and abraded using a "CS-10 CALIBRASE" (product name, manufactured by Taber, abrasion wheel) under conditions of a load of 500 gf and 500 rotations per minute to abrade each coating. After the abrasion test, the weight was measured and the weight change (mg) was calculated using the following formula. Weight change (mg) = Weight before test - Weight after test ◎ and ○ indicate a passing grade. The evaluation results are shown in Table 3. ◎: Weight change is less than 20 mg. ○: Weight change of 20 mg or more, less than 30 mg, ×: Weight change of 30 mg or more.

[0375] [Table 11]

[0376] [Table 12]

[0377] [Table 13]

[0378] Table 14

[0379] Table 15

[0380] Table 16

[0381] Table 17

[0382] Table 18

[0383] Table 19

[0384] Table 20

[0385] Table 21

[0386] Table 22

[0387] Table 23

[0388] Table 24

[0389] [Table 25]

[0390] [Table 26]

[0391] Preparation of painted panels for multi-layer coating testing Example 142 The coated object was prepared by electrodepositing "Elecron GT-10" (product name, manufactured by Kansai Paint Co., Ltd., cationic electrodeposition coating) to a dry film thickness of 20 μm onto a cold-rolled steel sheet treated with zinc phosphate conversion coating, and then heating it at 170°C for 30 minutes to cure the electrodeposited coating.

[0392] On the aforementioned substrate, aqueous paint composition No. 1 obtained in Example 44 was electrostatically applied using a rotary atomizing electrostatic coating machine to a dry film thickness of 25 μm as the intermediate coat paint composition. After standing for 5 minutes, preheating was performed at 80°C for 3 minutes to form an uncured intermediate coat film. Next, aqueous paint composition No. 50 obtained in Example 93 was electrostatically applied using a rotary atomizing electrostatic coating machine to a dry film thickness of 15 μm as the base coat paint composition. After standing for 5 minutes, preheating was performed at 80°C for 3 minutes to form an uncured base coat film. After standing for 3 minutes, preheating was performed at 80°C for 3 minutes, and then "KINO6510" (product name, manufactured by Kansai Paint Co., Ltd., hydroxyl / isocyanate group curing type acrylic resin / urethane resin type two-component organic solvent type clear coat paint) was electrostatically applied to a cured film thickness of 35 μm to form an uncured clear coat film. After standing for 7 minutes, the substrate was heated at 80°C for 30 minutes to simultaneously bake the intermediate coat, base coat, and clear coat, creating a multi-layer coating test panel.

[0393] Examples 143-192, Comparative Examples 7-8 In Example 142, each multi-layer coating test panel was prepared in the same manner as in Example 142, except that the combination of water-based paint compositions was as shown in Table 4.

[0394] Glass adhesion test In each of the multi-layer coating test panels obtained in Examples 142-192 and Comparative Examples 7-8, a urethane-based adhesive (product name "3740", manufactured by Sunstar Inc., automotive windshield agent) was applied in a shape with a width of 20 mm, a thickness of 3 mm, and a length of 100 mm or more. After covering with release paper, it was pressed down uniformly with a flat plate. After removing the flat plate, it was left to cure for 72 hours at a temperature of 23 ± 2°C and a humidity of 50 ± 5%. After that, the release paper was peeled off. Next, each multi-layer coating test panel was immersed in a constant temperature water bath set at 50°C for 240 hours, and then cooled by immersion in 23°C water for 1 hour, after which the following peel test was performed.

[0395] While pulling the hardened adhesive layer by hand at an angle of 90 degrees or more relative to the paint film, cuts were made with a utility knife at intervals of 2-3 mm, at an angle of approximately 60 degrees relative to the paint film, until the cuts reached the paint film surface. The peeling condition after removing the adhesive layer was evaluated according to the following criteria. ◎, ○+, and ○ indicate a passing grade. The evaluation results are shown in Table 4. ◎: No peeling of the adhesive layer was observed, and no exposure of the coating film was observed. ○+: The coating film is not destroyed; only the adhesive layer undergoes cohesive failure and peels off, but the adhesion between the coating film and the adhesive layer is largely maintained. ○: The paint film underwent cohesive failure and peeled off, with a width of less than 1 mm from the area where a cut was made with a utility knife. △: The paint film underwent cohesive failure and peeled off, with a width of 1 mm or more from the point where the utility knife was inserted. ×: Peeling is observed at the interface between the coating and the adhesive layer.

[0396] Chipping resistance test The multi-layer coating test plates obtained in Examples 142-192 and Comparative Examples 7-8 were placed on the specimen holder of the stone chip tester "JA-400" (product name, manufactured by Suga Test Machine Co., Ltd., chipping resistance test device). At -20°C, 50g of road crushed stone (S-5) as described in JIS A 5001 was impacted onto the test plate at a 90-degree angle using compressed air at 0.39 MPa (4 kgf / cm2) from a distance of 35 cm from the test plate. Afterwards, the obtained test plates were washed with water, dried, and cloth adhesive tape (manufactured by Nichiban Co., Ltd.) was applied to the coated surface. After peeling it off, the degree of scratching of the coating was visually observed and evaluated according to the following criteria. ◎ and ○ indicate a pass. The evaluation results are shown in Table 4. ◎: The scratch is extremely small, and the electrodeposited surface or the base steel plate is not exposed. ○: The scratch is small, and the electrodeposited surface or the base steel plate is not exposed. △: The scratch is small, but the electrodeposited surface or the bare steel plate is exposed. ×: The scratch is quite large, and a significant portion of the bare steel plate is exposed.

[0397] [Table 27]

[0398] [Table 28]

[0399] [Table 29]

[0400] [Table 30]

[0401] [Table 31]

[0402] Table 32

Claims

1. (A) (a1) A urethane resin portion obtained from a component comprising a compound having a secondary amino group and an alkoxysilyl group, and (a2) an isocyanate group-containing urethane prepolymer, (B)(b) An acrylic resin portion obtained from a component containing a polymerizable unsaturated group and a compound that does not have a hydroxyl group or has one hydroxyl group, comprising an aqueous dispersion of acrylic urethane composite resin particles, The (a1) compound having a secondary amino group and an alkoxysilyl group is obtained from a component comprising (a11) a compound containing a primary amino group and an alkoxysilyl group and (a12) a polymerizable unsaturated group-containing compound, and the (a2) isocyanate group-containing urethane prepolymer is obtained from a component comprising (a21) a polyisocyanate component and (a22) a polyol component. An aqueous dispersion of acrylic urethane composite resin particles having a core-shell structure consisting of a shell portion made of the urethane resin portion (A) and a core portion made of the acrylic resin portion (B).

2. The acrylic urethane composite resin particle aqueous dispersion according to claim 1, wherein the compound (a11) containing the primary amino group and the alkoxysilyl group comprises a compound (a11-1) containing a primary amino group, a secondary amino group and the alkoxysilyl group.

3. The acrylic urethane composite resin particle aqueous dispersion according to claim 1 or 2, wherein the polymerizable unsaturated group-containing compound (a12) contains (meth)acrylate.

4. The acrylic urethane composite resin particle aqueous dispersion according to claim 1 or 2, wherein the polyisocyanate component (a21) comprises an alicyclic polyisocyanate compound (a21-1).

5. The acrylic urethane composite resin particle aqueous dispersion according to claim 1 or 2, wherein the polyol component (a22) comprises at least one selected from polycarbonate polyol (a22-1) and polyether polyol (a22-2).

6. An aqueous paint composition containing an aqueous dispersion of acrylic urethane composite resin (AB) particles as described in claim 1.

7. The aqueous paint composition according to claim 6, wherein the aqueous dispersion of acrylic urethane composite resin (AB) particles is contained in an amount of 10 to 70 parts by mass based on 100 parts by mass of the total resin solids in the aqueous paint composition.

8. The aqueous paint composition according to claim 6, further comprising at least one resin selected from acrylic resin (C) and polyester resin (D).

9. The aqueous paint composition according to claim 6, further containing a hardening agent (E).

10. Step (I-1): A step of applying the aqueous coating composition according to any one of claims 6 to 9 onto the object to be coated to form an uncured colored coating film. A method for forming a coating film, comprising the step (I-2): a step of heat-curing the uncured colored coating film formed in step (I-1).

11. Step (II-1): A step of applying the aqueous coating composition described in any one of claims 6 to 9 onto the object to be coated to form an uncured intermediate coating film. Step (II-2): A step of applying a base coat paint composition onto the uncured intermediate coating film formed in step (II-1) to form an uncured base coat film. Step (II-3): A step of applying a clear coat paint composition onto the uncured base coat film formed in step (II-2) to form an uncured clear coat film. Step (II-4): A method for forming a multilayer coating film, comprising the step of simultaneously heating and curing the uncured intermediate coating film formed in step (II-1), the uncured base coat film formed in step (II-2), and the uncured clear coat film formed in step (II-3).

12. Step (IV-1): A step of applying the aqueous coating composition described in any one of claims 6 to 9 onto the object to be coated to form an uncured intermediate coating film. Step (IV-2): A step of applying the aqueous paint composition according to any one of claims 6 to 9 onto the uncured intermediate coating film formed in step (IV-1) to form an uncured base coat film. Step (IV-3): A step of applying a clear coat paint composition onto the uncured base coat film formed in step (IV-2) to form an uncured clear coat film. A method for forming a multilayer coating, comprising: step (IV-4): a step of simultaneously heat-curing the uncured intermediate coating film formed in step (IV-1), the uncured base coat coating film formed in step (IV-2), and the uncured clear coat coating film formed in step (IV-3).

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