WO2007145368A1 - Coating composition - Google Patents

Abstract

Disclosed is a coating composition to be used as a first colored coating composition (A) in a method wherein a first colored coating film is formed by applying a first colored coating composition (A) over an object to be coated, a second colored coating film is formed by applying an aqueous second colored coating composition (B) over the first colored coating film, a clear coating film is formed by applying a clear coating composition (C) over the second colored coating film, and then the thus-formed first colored coating film, second colored coating film and clear coating film are baked and cured at a time for forming a multilayer coating film. The coating composition contains 30-95 parts by mass of a hydroxylated resin (a) having an acid value of not more than 15 mgKOH/g and 5-70 parts by mass of a polyisocyanate compound (b), per 100 parts by mass of the resin solid content in the coating composition.

Description

 Specification

 Technical Field of Coating Composition

 In the present invention, a first colored paint, a water-based second colored paint, and a talya paint are sequentially applied on an object to be coated, and the resulting three-layer paint film is heated and cured simultaneously. The present invention relates to a paint for use as a first colored paint in a composition method. Background art

 As a method for forming a coating film on an automobile body, an electrodeposition coating film is formed on an object to be coated, and then an intermediate coating is applied, a baking and curing is applied, a base coating is applied, a clear coating is applied, and a baking and curing is applied. A method of forming a multi-layer coating film by the beta (3 C 2B) method has been widely adopted, but in recent years, from the viewpoint of energy saving, the baking hardening process after painting of the intermediate coating has been omitted, After the electrodeposition coating is formed, the intermediate coating is applied, the base coat coating is applied, the tarrier coating is applied, and the baking coating is performed. A three-coat one-bake (3 C 1 B) method is used to form a multilayer coating. An attempt has also been made (see, for example, JP-A-10-216617).

 However, the 3 C 1 B method has a drawback that the intermediate coating film and the base coat film are likely to be mixed, and the smoothness of the resulting coating film is reduced. This is an issue. Disclosure of the invention

An object of the present invention is to provide a coating composition for use as a first colored coating that can form a coating film excellent in smoothness and sharpness in the 3 C 1 B system. As a result of intensive studies to achieve the above object, the present inventors have determined that the 3 C 1 B method When a paint containing a low acid value hydroxyl group-containing resin and a polyisocyanate compound is used as the first colored paint in the coating process of the multi-layer paint film, the multi-layer paint film having excellent smoothness and sharpness The present invention has been completed.

 Thus, the present invention provides the following steps (1) to (4):

 (1) The first colored paint (A) is applied on the object to be coated to form the first colored coating film.

(2) A water-based second colored paint (B) is applied on the formed first colored coating film to form a second colored coating film.

 (3) On the second colored coating film to be formed, paint the Talia paint (C) to form a Talia paint film.

 (4) The first colored coating film, the second colored coating film and the clear coating film to be formed are simultaneously baked and cured.

Coating composition for use as the first colored paint (A) in the method of forming a multi-layer coating film by using a resin solid content of 100 parts by mass in the paint composition as a reference, 15 mg KOH / A coating composition comprising 30 to 95 parts by mass of a hydroxyl group-containing resin (a) having an acid value of g or less and 5 to 70 parts by mass of a polyisocyanate compound (b) is provided. is there.

 According to the present invention, a multilayer coating film excellent in smoothness and sharpness can be easily formed by the 3 C 1 B method.

 Hereinafter, the multilayer coating film forming method using the coating composition of the present invention will be described in more detail. Process (1)

In this step, the first colored paint (A) is applied onto the object to be coated to form the first colored coating film. Article The object to which the first colored paint (A) can be applied according to the present invention is not particularly limited. For example, an outer plate part of an automobile body such as a passenger car, a truck, a motorcycle, a bus, etc .; For example, the outer plate portion of home electric products such as telephones and audio equipment can be cited, and among them, the outer plate portion of automobile bodies and automobile parts are preferable.

 Further, the material of the above-mentioned object to be coated is not particularly limited. For example, iron, aluminum, brass, iron, tinplate, stainless steel, zinc plating steel, alloyed zinc (Zn—A1, Z n_Ni, Zn—Fe, etc.) Metal materials such as matt steel; polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, Resin materials such as polyurethane resin and epoxy resin and various plastic materials such as FRP; inorganic materials such as glass, cement and concrete; wood; fiber materials (paper, cloth, etc.), etc. However, metal materials and plastic materials are suitable.

 The object to be coated may be one in which a surface treatment such as a phosphate treatment, a chromate treatment, or a complex oxide treatment is performed on a metal surface of the metal material or a vehicle body formed from the metal material. Further, the object to be coated may be one in which an undercoat film such as various electrodeposition paints is formed on the metal base material, the vehicle body, etc. Among them, the undercoat film is formed by a cationic electrodeposition paint. A formed vehicle body is particularly suitable. First colored paint (A)

 In the present invention, as the first colored paint (A), a hydroxyl group-containing resin (a) having an acid value of 15 mg K OHZ g or less based on 100 parts by mass of the resin solid content in the paint composition is used. A coating composition comprising 0 to 95 parts by mass and 5 to 70 parts by mass of the polyisocyanate compound (b) (hereinafter referred to as the coating composition of the present invention) is used.

In the present specification, the resin solid content in the paint (composition) is the total amount of the base resin and the crosslinking agent in the paint (composition). Hydroxyl-containing resin (a)

 The hydroxyl group-containing tsukizuki (a) used as the base resin in the coating composition of the present invention preferably has at least one hydroxyl group in one molecule and generally has an acid value of 15 mg KO HZ g or less. Wow! To 12 mg KOH / g, more preferably 3 to 10 mg KOH / g, specifically, for example, containing a hydroxyl group and optionally further containing a carboxyl group. Examples of the resins include polyester resins, acrylic resins, polyether resins, polycarbonate resins, and urethane resins. Of these, a hydroxyl group-containing acrylic resin and a hydroxyl group-containing polyester resin are preferable, and a hydroxyl group-containing polyester resin is particularly preferable.

 The hydroxyl group-containing polyester resin can be produced by, for example, an esterification reaction or a transesterification reaction between a polybasic acid component and a polyhydric alcohol component, and specifically, for example, a carboxyl group in the polybasic acid component. And an equivalent ratio of hydroxyl groups in the polyhydric alcohol component (COOH / OH) is less than 1, and the esterification reaction can be carried out in a state where there are more hydroxyl groups than carboxyl groups. The acid value of the hydroxyl group-containing polyester resin can be adjusted by, for example, performing the esterification reaction while tracking the acid value and terminating the esterification reaction when the target acid value is reached. .

The polybasic acid component is a compound having at least two carboxyl groups in one molecule, such as phthalic acid, isophthalic acid, terephthalic acid, succinic acid, dartaric acid, adipic acid, azelaic acid, sebacic acid, Polybasic acids such as tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid and pyromellitic acid; anhydrides of these polybasic acids; lower alkyl esterified products of these polybasic acids These can be used alone or in combination of two or more. The polyhydric alcohol component is a compound having at least two hydroxyl groups in one molecule, such as ethylene glycol, 1,2-propylene glycol, 1,2-butyl. Tylene glycol, 2,3-butylene glycol, 1,2 monohexanediol, 1,2-dihydroxycyclohexane, 3-ethoxyprono. Α-glycols such as N-1,2-diolone, 3-phenoxypropane-1,2-diol; neopentylglycol, 2-methinoleyl-1,3-propanediole, 2-methyl-1,2,4-1pentane Honole, 3-methyl-1,3-butanediol, 2-ethyl-1-, 3-hexanediol, 2,2-decyl-1,3-propanediol, 2,2,4-trimethyl_1,3-pentanediol, 2—Petinole _ 2—Echinoley 1, 3—Prono. 1-, 3-diol, 2-methyl-1, 2-phenylpropane, 1, 3-diol, 1,3-propylene glycol, 1,3-butylene glycol, 2-ethyl-1, 3-Otatanediol, 1,3-dihydroxycyclohexane, 1,4-dihydroxycyclohexane, 1,4-dihydroxycyclohexane, 1,5-pentanediol, 1,6-dihexanediol, 2, 5-monohexanol, 3-methylolene 1,5-pentanediol, 1,4-dimethylolcyclohexane, tricyclodecane dimethanol, 2,2-dimethyl-3-hydroxypropyl-1,2,2-dimethyl 1-Hydroxypropionate (this is an esterified product of hydroxybivalic acid and neopentyldaricol), Bisphenol Inore, Bisphenol Nore F, Bis (4-Hydroxyhexynole)-2, 2-Propane, Bis (4-Hydroxyhexyl) Methane, 3, 9-Bis (1,1-Dimethyl-1-2-Hydroxychetyl) 1-2 , 4, 8, 10—Tetraoxaspiro [5,5] undecane, jetylene glycol, triethylene glycol, glycerin, diglycerin, triglycerin, pentaerythritol, dipentaerythritol, sonolebitol, mannitol, trimethylol Ethane, trimethylolpropane, ditrimethylolpropane, tris (2-hydroxyxetyl) isocyanurate, and the like can be used alone or in combination of two or more.

The esterification or transesterification reaction of the polybasic acid component and the polyhydric alcohol component can be performed by a method known per se, for example, the polybasic acid component and the polyhydric alcohol. By subjecting the components to polycondensation at a temperature of about 180 to about 250 ° C. The hydroxyl group-containing polyester resin can be modified with a fatty acid, a monoepoxy compound, or the like, if necessary, during the preparation of the polyester resin or after the esterification reaction. Examples of the fatty acids include 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, tung oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor Oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid, and the like. Examples of the monoepoxy compound include “CARDYURA E 10 P” (trade name, manufactured by Japan Epoxy Resin Co., Ltd., glycidyl ester of synthetic hyperbranched fatty acid). ) And so on.

 The hydroxyl group-containing polyester resin generally has an acid value within the range of 15 mgKOH / g or less, particularly 1 to 12 mgKOH / g, more particularly 3 to 1 OmgKOH / g, from the viewpoint of smoothness of the resulting coating film. And generally having a number average molecular weight in the range of 500 to 5,000, in particular 700 to 3,000, more particularly 1,000 to 2,000. The hydroxyl group-containing polyester resin generally has a hydroxyl value in the range of 50 to 20 OmgKOHZg, particularly 70 to 17 OmgKOHZg, more particularly 100 to 150 mg KOH / g, from the viewpoint of the curability of the coating film. Is preferred.

 The “number average molecular weight” and “weight average molecular weight” of the resin or polymer in the present specification are those of the resin or polymer measured by gel permeation chromatography (“HLC81 20GPCJ” manufactured by Tosohichi Co., Ltd.). The number average molecular weight or the weight average molecular weight is a value converted based on the molecular weight of standard polystyrene.This measurement is performed by using “TSKg e 1 G 1 4000HXL”, “TSKg el G—3000HXL”, “TSKg el G — 2500HXL ”and“ TSKg el G—2000HXL ”(both trade names, manufactured by Tosoh Corporation), mobile phase tetrahydrofuran, measurement temperature 40 ° (: flow rate ImLZmin and detector RI conditions were used. Can be done.

The hydroxyl group-containing acryl resin is a hydroxyl group-containing polymerizable unsaturated monomer and optionally Furthermore, it can be produced by (co) polymerizing at least one polymerizable unsaturated monomer component including other polymerizable unsaturated monomer copolymerizable with the monomer under ordinary conditions, and the coating obtained From the standpoint of membrane smoothness, etc., it is generally 15 mgKOHZg or less, particularly 1 to 12 mgKOH / g, more particularly 3 to 10 mg KOHZ g, and generally 1,000 to 50,000, It is particularly preferred to have a number average molecular weight in the range of 1,500 to 30,000, more particularly in the range of 2,000 to 10,000. The hydroxyl group-containing acryl resin is generally 20 to 200 mg KO H / g, particularly 30 to L, 50 mg K 0 H / g, more particularly 50 to 100 mg KOH / g, from the viewpoint of the curability of the coating film. It is preferable to have a hydroxyl value within the above range.

 The hydroxyl group-containing polymerizable unsaturated monomer is a compound having at least one hydroxyl group and polymerizable unsaturated bond in one molecule, such as 2-hydroxyxetyl (meth) acrylate, 2-hydroxypropyl. Monoesterified products of (meth) acrylic acid and dihydric alcohols having 2 to 8 carbon atoms, such as (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; (Meth) acrylic acid and ε-force prolatatone modified product of monoesterified product of dihydric alcohol having 2 to 8 carbon atoms; aryl alcohol; having polyoxyethylene chain whose molecular terminal is a hydroxyl group (meth) acrylate Etc.

 In the present specification, (meth) atallylate is a generic name for attalylate and metatalylate, and (meth) atalylic acid is a generic name for acrylic acid and methacrylic acid.

Other polymerizable unsaturated monomers that can be copolymerized with the hydroxyl group-containing polymerizable unsaturated monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, and η monopropyl (meth) acrylate. I-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexynole (meth) acrylate, Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Noel (meth) acrylate, tridecyl (meth) ) Atarylate, Lauryl (meth) Atarylate, Stearyl (meth) Atarylate, “Isostearyl Atarylate” (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), Cyclohexyl (meth) acrylate, Methylcyclohexyl ( Meta) Atalylate, t-Butyl hex Hexyl (Meth) Atarylate, Cyclododecyl (Meth) Atylate, etc. Alkyl or Cycloalkyl (Meth) Atarylate; Isobornyl (Meth) Acrylate, etc. Polymerizable unsaturated monomers; polymerizable unsaturated monomers having adamantyl groups such as adamantyl (meth) acrylate; butyl aromatic compounds such as styrene, α-methylstyrene and butyltoluene; butyltrimethoxysilane, vinyltriethoxysilane, Noretorisu (2 main Tokishetokishi) silane, _I i (meth) Atari port Ino les acryloxypropionic built Increment Tokishishiran, .gamma. (meth) polymerizable unsaturated monomer having an alkoxysilyl group such as Atari Roy Ruo carboxymethyl pro built triethoxysilane Perfluoroalkyl (meth) acrylate, perfluorooctyl cetanol (meth) perfluoroalkyl (meth) acrylate, etc .; Polymerization with fluorinated alkyl groups such as fluorephine Unsaturated monomer; polymerizable unsaturated monomer having a photopolymerizable functional group such as maleimide group; vinyl compounds such as Ν-butylpyrrolidone, ethylene, butadiene, chloroprene, propionic acid butyl, and acetic acid butyl; (meth) acrylic acid , Maleic acid, crotonic acid, Carboxyl group-containing polymerizable unsaturated monomers such as poxchethyl atylate; (meth) acrylonitrile, (meth) acrylamide, dimethylaminopropinole (meth) acrylamide, dimethylaminoethyl (meth) acrylate, glycidyl Nitrogen-containing polymerizable unsaturated monomers such as adducts of (meth) acrylate and amines; glycidyl (meth) acrylate,; 3-methyldaricidinole (meth) END talate, 3, 4 monoepoxycyclohexylmethyl Epoxy group-containing polyunsaturated monomers such as (meth) acrylate, 3,4-epoxycyclohexino retinole (meth) acrylate, 3,4 epoxy propyl propyl (meth) acrylate, allyl glycidyl ether ; Polio whose molecular terminal is an alkoxy group Has a xylene chain (Meth) attalylate; 2-acrylamido 2-methylpropane sulfonic acid, allylic sulfonic acid, sodium styrene sulfonate, sulfoethyl methacrylate and its polymerizable unsaturated compounds having sulfonic acid groups such as sodium salt and ammonium salt Monomers; 2 One-way Inoleoxyethylenoside Acid Phosphate, 2-Methacryloylolexchichinore Acid Acid Phosphate, 2-acryloyloleoxypropinoreaside Acid Phosphate, 2-Methacryloyloxypropyla Polymerizable unsaturated monomers with phosphate groups such as cydphosphate; 2—Hydroxy 4 _ (3 _Metataloyloxy 2 —Hydroxy propoxy) Benzophenone, 2 —Hydroxy 1 4 (3— Ataliloyloxy 2-hydroxypropoxy) Benzohue 2, 2 '— Dihydroxyloxy 4- (3-methacryloyloxy 2-hydroxypropoxy) Benzophenone, 2, 2' — Dihydroxyl 4-1- (3-Atalyloxyloxy 2--hydroxyloxypropoxy ) Benzophenone, 2-(2, Monohydroxy _5, Monomethacryloyloxychetilfeninole) 1 2H-polymerizable unsaturated monomer having UV-absorbing group such as benzotriazole; 4- (meth) 1,2,2,6,6-pentamethylpiperidine, 4- (meth) attaroyloxy 2,2,6,6-tetramethylbiperidine, 4-cyanol 4-1- (meth) attaroyloxy Minnow 2, 2, 6, 6—Tetramethinoleviperidine, 1- (Meth) Atari Royl 1 4- (Meth) Atari mouth Inoleamino 1, 2, 2, 6, 6-Tetramethinoleviperidine, 1- (Meta) Atariroyl 4-Cyanol 4 _ (Meta) Atari mouth Inolamino 1, 2, 6, 6-Tetramethinorebiperidine, 4-Crotonoyloxy 2, 2, 6, 6-Tetramethylbiperidine, 4-Crotonoylamino 2 , 2, 6, 6-tetramethinoleviberidine, 1_crotonol 1 4_crotonoxyl 1, 2, 6, 6-tetramethinorepiperidine Unsaturated monomers; acrolein, diacetone acrylamide, diacetone methacrylamide, acetocetoxyl methacrylate, formylstyrene, bialkyl alkyl ketone having 4 to 7 carbon atoms (eg, vinyl methyl ketone) , Vinylethylketone, vinylbutinoleketone) Examples thereof include polymerizable unsaturated monomer compounds having a sulfonyl group, and these can be used alone or in combination of two or more.

 The acid value of the hydroxyl group-containing acrylic resin is, for example, that a polymerizable unsaturated monomer component is a carboxyl group-containing polymerizable unsaturated monomer such as (meth) acrylic acid, maleic acid, crotonic acid, or β-carboxyethyl acrylate. It can be adjusted by using and adjusting the blending amount.

 The hydroxyl group-containing polyester resin or hydroxyl group-containing acrylic resin is used in combination with a so-called urethane-modified polyester resin or urethane-modified acryl resin obtained by extending a polyisocyanate compound to a part of the hydroxyl group in the resin by a urethanization reaction to increase the molecular weight. May be.

 In addition, the hydroxyl group-containing resin (a) has a number average molecular weight of generally from 100 to 2, 000, particularly from 2,000 to 1,700, from the viewpoint of smoothness of the resulting coating film. In particular, it is preferable to use together with a polyol compound (c) in the range of 400 to 1,200, more particularly in the range of 400 to 700.

 Examples of the polyol compound (c) include polyether polyols, polyester polyols, polycarbonate polyols, polyptagene polyols, hydrogenated polybutadiene diene polyols, among which polyester polyols and polycarbonate polyols are preferred, and polyester polyols are preferred. Particularly preferred. These polyol compounds (c) can be used alone or in combination of two or more.

Examples of the polyether polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene dariconol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, One or more of compounds having at least two active hydrogen atoms, such as neopentinoreguri cornore, glycerin, trimethylololethane, trimethylololepronone, sorbitol In addition, one or more cyclic ether monomers such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene oxide are subjected to addition polymerization by a conventional method. In particular, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like can be used.

 Examples of the polyester polyol include polyester polyol obtained by esterifying a polyhydric alcohol component and a polybasic acid component, and ring-opening reaction of a lactone compound using a polyhydric alcohol component as an initiator. Examples thereof include polyester polyols obtained. As the polyhydric alcohol component and the polybasic acid component, for example, those exemplified in the description of the hydroxyl group-containing polyester resin can be used, and these polyhydric alcohol component and polybasic acid component are each independently or Two or more types can be used in combination. Further, examples of the above-described latonone compound include ε-force prolatatatone, poly-methyl-δ-valerolactone, and the like. Further, the polyester polyol preferably has an acid value generally less than 5 mg KOH / g, particularly 0.00 l to 3 mg KOH / g, more particularly 0.01 to 2 mg KO H / g. In particular, the number average molecular weight is in the range of 400 to 700 and the acid value is less than 5 mg KOH / g, in particular 0.00 l to 3 mg KOH / g, more particularly in the range of 0.01 to 2 mg KOH / g. Some are particularly suitable.

Examples of the polycarbonate polyol include a reaction product of a polyhydric alcohol and phosgene, and a ring-opening polymer of cyclic ester carbonate (alkylene carbonate, etc.). Examples of the polyhydric alcohol include 3-methyl-1,1,5-pentanediol and 1,6-hexanediol. Examples of the cyclic carbonate include ethylene carbonate, trimethylene carbonate, and tetramethylene. And carbonate. Further, the polycarbonate polyol may have an ester bond as well as a carbonate bond in the molecule. The polyol compound (c) is usually 1 to 50 parts by weight, preferably 5 to 40 parts by weight, more preferably 10 based on 100 parts by weight of the resin solid content in the first colored paint (A). It can be used at a ratio of ˜30 parts by mass. Polyisocyanate compound (b)

 The polyisocyanate compound (b) used as a crosslinking agent in the coating composition of the present invention is a compound having at least two isocyanate groups in one molecule, such as aliphatic polyisocyanate, alicyclic Examples thereof include polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates. '

 Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1, 2 1-Putylene Diisocyanate, 2, 3-Butylene Diisocyanate, 1, 3-Petylene Diisocyanate, 2, 4, 4-— or 2, 2, 4--Trimethylhexamethylene Disocyanate, 2, 6 — Aliphatic diisocyanates such as disoocyanatomethyl caproate; lysine ester triisocyanate, 1,4,8-triisocyanatooctane, 1,6,11 1-triisocyanatodecane, 1,8-diisocyanato 4_isocyanatomethyloctane, 1,3,6-triisocyanatohexane, 2,5,7-trimethyl-1,8 Such Jiisoshi annatto 5 _ isocyanatomethyl aliphatic triisobutyl Xia sulfonates such as methyl OTA Tan it is possible elevation gel.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-1,3, 5,5-Trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), methyl _ 2,4-cyclohexane Diisocyanate, methyl-2,6-cyclohexanediisocyanate, 1,3_ or 1,4 monobis (isocyanatomethyl) cyclohexane (common name: hydrogenated xylylene diamine) or a mixture thereof, norbornane 1,3,5-triisocyanatocyclohexane, 1,3,5_trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) 1-2 5-Di (isocyanatomethyl) -bicyclo (2. 2. 1) heptane, 2- (3-isocyanatopropyl) 1, 2, 6-di (isocyanatomethyl) bibicyclo (2. 2. 1) heptane 3— (3-Isocyanatopropyl) 1 2,5-Di (isocyanatomethyl) 1Bicyclo (2. 2. 1) Heptane, 5— (2-Isocyanatoethyl) 1 2 _Isocyanatomethyl 1 3 — (3-Isocyanatopropyl) -bicyclo (2. 2. 1) Heptane, 6- (2-Isocyanatoethyl) 1 2-Isocyanatomethyl 1 3- (3-Isocyanatopropyl) Ibicyclo (2. 2. 1) Heptane, 5— (2-Isocyanatoethyl) 1 2-Isocyanatomethinole 2-— (3-Isocyanatopropyl) Ibicyclo (2. 2. 1) Iheptane, 6 _ (2-Isocyanatoethyl) 1 2 —Isocyanatomethyl-2- (3_isocyanatopropyl) Bicyclo (2.2.1) Aliphatic triisocyanates such as heptane can be mentioned.

 Examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato 1,4-deethylbenzene, 1, 3_ or 1, 4, 5-bis (1 isocyanato 1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or a mixture of araliphatic diisocyanates such as 1, 3, 5-triisocyanatomethylbenzene Group triisocyanate and the like.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4, 4, 1-diphenylenoresiocyanate, 1,5-naphthalene. Isocyanate, 2, 4 '— or 4, 4' — Diphenylmethane diiso Aromatics such as cyanate or mixtures thereof, 2,4 one or 2,6_tolylene diisocyanate or mixtures thereof, 4, 4 'monotoluidine diisocyanate, 4, 4'-diphenyl monoterdiisocyanate, etc. Diisocyanate; triphenylmethane 1, 4, 4 '4''one triisocyanate, 1, 3, 5-triisocyanatobenzene, 2, 4, 6-triisocyanato toluene and other aromatic triisocyanates; 4 , 4 ′ — Diphenylmethane 1, 2, 2,, 5, 5 ′ — aromatic tetraisocyanates such as tetraisocyanate.

 Examples of the polyisocyanate derivatives include dimer, trimer, biuret, alophanate, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenylisocyanate of the polyisocyanate compound described above. (Crude MD I, Polymeric MD I), Crude TD I, and the like.

 The above polyisocyanates and their derivatives may be used alone or in combination of two or more. Of these polyisocyanate compounds, aliphatic diisocyanates, alicyclic diisocyanates, and derivatives thereof can be used alone or in combination of two or more.

 It is preferable that the polyisocyanate compound (b) has a number average molecular weight in the range of generally 300,000 or less, particularly 120 to 1,500.

The ratio of the polyisocyanate compound (b) to the hydroxyl group-containing resin (a) is not particularly limited, but the polyisocyanate compound (b) may be used from the viewpoint of coating curability and coating stability. The equivalent ratio of the isocyanate group to the hydroxyl group of the hydroxyl group-containing resin (a) (NC O / OH) is generally 0.5 to 2. ◦, especially 0.8 to 1.5, more particularly 0.9 to 1.2: It is preferable to be within the range. Paint composition The coating composition of the present invention comprises 30 to 95 parts by weight, preferably 40 to 80 parts by weight of the hydroxyl group-containing resin (a), based on 100 parts by weight of resin solids in the coating composition. Parts by mass, more preferably within the range of 50 to 70 parts by mass and 5 to 70 parts by mass of the polyisocyanate compound (b), preferably 10 to 50 parts by mass, more preferably 20 It can be contained within the range of ~ 40 parts by mass.

 The coating composition of the present invention preferably contains a polyol compound (c), and the content of the polyol compound (c) is based on 100 parts by mass of the resin solid content in the coating composition. Generally, it is preferable to be within the range of 1 to 50 parts by mass, particularly 5 to 40 parts by mass, and more particularly 10 to 3 parts by mass.

 As the coating composition of the present invention, the acid value is in the range of 3 to 15 mg KOH / g and the number average molecular weight is based on 100 parts by mass of the resin solid content in the coating composition. 3 to 95 parts by mass of a hydroxyl group-containing resin (a) in the range of 1, 0 0 0 to 10 0, 0 0 0, 5 to 40 parts by mass of a polyisocyanate compound (b) A coating composition containing 1 to 30 parts by mass of a polyol compound (c) having an average molecular weight in the range of 400 to 70 ° is preferred, and the resulting coating film has excellent smoothness. For this reason, the polyol compound (c) having a number average molecular weight of 400 to 700 is particularly preferably a polyester polyol and / or a polycarbonate polyol, especially a polyester polyol.

 The coating composition of the present invention can contain a modifying resin such as polyurethane resin, acrylic resin, alkyd resin, polyester resin, silicone resin, fluorine resin, epoxy resin in addition to the hydroxyl group-containing resin (a). In particular, it is desirable to include at least one resin selected from the group consisting of a polyurethane resin, a polyester resin, and an attalinole resin from the viewpoint of finish and chipping resistance.

In addition to the polyisocyanate compound (b), the coating composition of the present invention can also use a melamine resin or the like as an auxiliary crosslinking agent. As a melamine resin that can be used For example, methylolated melamine resin obtained by reaction of melamine and aldehyde can be mentioned. Examples of the aldehyde include formaldehyde and paraformaldehyde. It is also possible to use those obtained by etherifying some or all of the methylol groups of the methylolated melamine resin with monoalcohol. Examples of the alcohol used for etherification include methyl alcohol, ethyl alcohol, and _n- propino. Examples include leaanolol, i-propinoreal alcohol, n-butinoreanolecol, i_butylanolol, 2-ethylbutanol, 2-ethylhexanol and the like. Specific examples of the melamine resin include, for example, Cymel 3 0 3, Cymel 3 2 3, Sai Menole 3 2 5, Saimenore 3 2 7, Saimenole 3 5 0, Saimenole 3 70, Saimenole 3 80, Cymel 3 8 5, Cymel 2 1 2, Cymel 2 5 1, Cymel 2 5 4, My Coat 7 7 6 8 (all of these are trade names, manufactured by Nihon Cytec Industry Co., Ltd.); Resimin 7 3 5, Resimin 7 40 7 4 1, Resimin 7 4 5, Resimin 7 4 6, Resimin 7 4 7 (all are trade names, manufactured by Monsanto); Sumimar M 5 5, Sumimar M 30 W, Sumimar M 50 W (above, All of them are trade names, manufactured by Sumitomo Chemical Co., Ltd.); Euban series such as Uban 20 SB manufactured by Mitsui Chemicals.

 When the melamine resin is used as an auxiliary crosslinking agent, a sulfonic acid such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, or a salt of these acids and amines is used as a catalyst. be able to.

 The melamine resin is generally 30 parts by mass or less, preferably in the range of 1 to 20 parts by mass per 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a) and the polyisocyanate compound (b). Can be used in

In addition, the coating composition of the present invention preferably contains silicon dioxide (d) from the viewpoint of the sharpness of the resulting coating film, and since the resulting coating film is excellent in smoothness, silicon dioxide (d In particular, silicon dioxide having a carbon content of 1.0% by mass or less, particularly 0.5% by mass or less, and particularly 0.1% by mass or less is particularly suitable. In this specification, the carbon content of silicon dioxide is the mass ratio of carbon contained in silicon dioxide to silicon dioxide (d), and is a solid-state carbon analyzer EMI A— 1 10 (trade name, HORIBA, Ltd. Can be used. Specifically, carbon dioxide is charged into a crucible, heated to 1.000 ° C, the generated gas components are analyzed by infrared absorption, and the total amount of carbon monoxide and carbon dioxide detected is detected. The amount of carbon is obtained, and the mass fraction of the amount of silicon dioxide charged is the amount of carbon in silicon dioxide.

 The reason why the coating composition of the present invention has a low carbon content, that is, a low hydrophobic group and a relatively high hydrophilic silicon dioxide (d), is clearly why the coating film has excellent sharpness. However, when the aqueous second colored paint (B) is applied over the paint composition of the present invention, Γ this relatively hydrophilic silicon dioxide (d) migrates to the vicinity of the interface between the two coating films. Thus, it is presumed that the mixed layer between the coating films is suppressed.

 The amount of silicon dioxide (d) is generally within the range of 0.1 to 5 parts by weight, particularly 0.5 to 2 parts by weight, based on 100 parts by weight of resin solids in the coating composition. Is preferred.

From the viewpoint of the smoothness of the resulting coating film, the coating composition of the present invention is applied such that the cured film thickness is 30 μπι and heated at 70 ° C. for 5 minutes. G _7. ) Is generally applied in a range of 0 to 20% by weight, in particular 0.01 to 15% by weight, more particularly 3 to 10% by weight, and a cured film thickness of 30 m. ° the gel fraction of the coating film when heated for 10 minutes at C (G ₉₀₎ is generally 30 to 100 mass _^0/0, especially 1:50 to 00 wt%, more particularly from 70 to 1 00% by weight, more particularly It is desirable that it be in the range of 85 to 100% by mass.

The gel fraction (G _7. ) And gel fraction (G _9. ) Can be measured by the following method: First, the coating composition of the present invention on a polypropylene plate has a cured film thickness of 30. Paint to μm and heat at 70 ° C or 90 ° C for 10 minutes. Next, the coating film on the polypropylene plate is collected, and the mass (W _a ) is measured. After that, the coating film was washed with 200 mesh. The coating weight (W _b ) after placing in a tenth steel mesh container, extracting while refluxing in aceton heated to 64 ° C for 5 hours, and drying for 60 minutes at 110 ° C is measured. Measure the residual fraction of insoluble coating film (mass%) calculated according to the following formula as the gel fraction.

Gel fraction (mass./.) = (W _b / W _a ) X 1 0 0

The gel fraction (G _7. ) And the gel fraction (G _9. ) Of the coating composition of the present invention can be adjusted, for example, by adjusting the blending amount of the curing catalyst in the coating composition.

 The coating composition of the present invention may contain a color pigment and a pigment or extender pigment that are usually used in the field of paint, and these pigments can be used alone or in combination of two or more.

 Examples of the coloring pigment include titanium dioxide, carbon black, zinc oxide, zinc phosphate, anoleminium phosphate, zinc molybdate, calcium molybdate, bitumen, ultramarine blue, cobalt blue, phthalocyanine blue, indanthrone blue, Synthetic Yellow Iron Oxide, Transparent Berry (Yellow), Bismaspanadate, Titanium Yellow, Zinc Yellow (Zincero I), Monoazo Yellow, Isoindolinone Yellow, Metal Complex Azo Yellow, Kinoff Talon Yellow, Benzimidazolone Yellow, Mono Red, Yellow B Don letdo, Azo lake (Mn salt), Quinakuri Don magenta, Ansanthrone orange, Gianslaquininorelet, Peri remnanolane, Kinata don magenta, Peri reren let, di Examples include topyrrolopyrrole chromium permillion, chlorinated phthalocyanine green, brominated phthalocyanine green, pyrazolone orange, benzimidazolone orange, dioxazine violet, and perylene violet. Of these, titanium dioxide and carbon black are preferred. Can be used.

When the coating composition of the present invention contains the color pigment, the amount of the color pigment is based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a) and the polyisocyanate compound (b). Usually, it can be in the range of 1 to 120 parts by mass, preferably 3 to 100 parts by mass, and more preferably 5 to 90 parts by mass. Examples of the extender pigment include barita powder, barium sulfate, palium carbonate, calcium carbonate, gypsum, clay, white carbon, diatomaceous earth, tanolec, magnesium carbonate, alumina white, gloss white, and my power flour. Of these, barium sulfate and pino or talc are preferably used.

 As the extender, a multilayer coating having an excellent smoothness appearance can be obtained by using barium sulfate having an average primary particle diameter of 1 μm or less, particularly in the range of 0.1 to 0.8 μm. A film can be formed.

 The average primary particle size of the barium sulfate is the value obtained by observing the barium sulfate with a scanning electron microscope and averaging the maximum diameters of 2 ° of barium sulfate on a straight line drawn randomly on the electron micrograph. .

 When the coating composition of the present invention contains the extender, the amount of the extender is based on the total solid content of 100 parts by mass of the hydroxyl group-containing resin (a) and the polyisocyanate compound (b). 1 to 120 parts by mass, preferably 1 to 100 parts by mass, more preferably 16 to 90 parts by mass, and the average primary particle size is 1 μm. The compounding amount of barium sulfate of m or less is usually 1 to 100 parts by mass, preferably 1 based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a) and the polyisocyanate compound (b). It can be in the range of 1 to 90 parts by mass, more preferably 16 to 80 parts by mass.

 If necessary, the coating composition of the present invention further includes a luster pigment, a curing catalyst, an ultraviolet absorber, a light stabilizer, an antifoaming agent, a plasticizer, an organic solvent, a surface conditioner, an antisettling agent, and a viscosity adjustment. Conventional paint additives such as additives can be contained alone or in combination of two or more.

Examples of the bright pigment include, for example, anoreminium, copper, zinc, brass, nickel, aluminum oxide, mica, aluminum oxide coated with titanium oxide and iron oxide, mica coated with titanium oxide and iron oxide, Examples include glass flakes and hologram pigments. Examples of the curing catalyst include tin octylate, dibutyltin diacetate, Butyltin di (2-ethyl hexanoate), diptyl tin dilaurate, dioctyl tin diacetate, dioctyl tin di (2-ethyl hexanoate), dibutyl tin oxide, dioctyl tin oxide, dibutyl tin fatty acid salt, 2-ethyl hexane Organometallic compounds such as lead acid, zinc octylate, zinc naphthenate, fatty acid zinc, cobalt naphthenate, calcium octylate, copper naphthenate, tetra (2-ethylhexyl) titanate; tertiary amine; phosphate compound Among them, dibutyltin diacetate and dibutyltin dilaurate can be preferably used.

 When the coating composition of the present invention contains the curing catalyst, the amount of the curing catalyst is based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a) and the polyisocyanate compound (b). In general, it can be in the range of 0.001 to 2 parts by mass, preferably 0.005 to 0.5 parts by mass, and more preferably 0.01 to 0.1 parts by mass. .

 The coating composition of the present invention may be in the form of a one-component paint or a multi-component paint. From the viewpoint of storage stability, the hydroxyl group-containing resin (a) is used. A two-component paint comprising a main component contained and a curing agent component containing the polyisocyanate compound (b) is preferred. In general, the main agent further preferably contains a pigment, a curing catalyst and a solvent, and the curing agent component further preferably contains a solvent.

 In addition, the coating composition of the present invention may be in any form of an organic solvent-type paint and a water-based paint, but is preferably an organic solvent-type paint from the viewpoint of storage stability. In the present specification, the water-based paint is a paint whose main component is water, and the organic solvent-type paint is a paint containing substantially no water as a solvent.

The coating composition of the present invention described above is applied as the first colored coating (A) on the substrate by a method known per se, for example, air spray, airless spray, rotary atomizing coating machine or the like. Electrostatic application may be performed during painting. The coating film thickness is a cured film thickness, and is usually 10 to: Θθ μπι, preferably 10 to 50 / _tm, and more preferably 15 to 35 zm. The coating composition of the present invention can be applied on a coating object in which a metal member formed with an undercoat film of various electrodeposition coatings and a plastic member such as a bumper are integrated as necessary. Thus, there is an advantage that the coating color of the metal member and the plastic member can be matched and a multilayer coating film having excellent smoothness can be formed on both members. Process (2)

 According to the present invention, the aqueous second colored paint (B) is applied onto the first colored coating film formed by the above step (1).

The coating of the water-based second colored paint (B) is generally from 70 to 100% by mass in terms of the solid content of the first colored paint film from the viewpoint of suppression of sagging and smoothness of the resulting paint film. In particular, 80 to 100 mass%, more particularly 90 to 10 mass. / ₀ , and preferably from the viewpoint of smoothness of the resulting coating film, the gel fraction of the first colored coating film is generally 0 to 70% by mass, It is particularly preferable to carry out the reaction while being in the range of 0.01 to 30% by mass, more particularly 1 to 20% by mass, and even more particularly 3 to 10% by mass. The solid content and the gel fraction of the first colored coating film can be adjusted by, for example, preheating (preheating), air blowing, etc. before applying the aqueous second colored paint (B). The preheating is usually performed at a temperature of about 50 ° C. to about 110 ° C., preferably about 60 ° C. to about 80 ° C., in a drying furnace for the article coated with the first colored paint (A). For about 30 seconds to about 30 minutes, preferably about 1 to about 15 minutes, more preferably about 2 to about 10 minutes, particularly preferably about 3 to about 5 minutes, directly or indirectly In addition, the above-mentioned air procedure is usually performed by spraying air heated to normal temperature or a temperature of about 25 ° C. to about 80 ° C. on the surface to be coated. You can.

The solid content of the first colored coating film can be measured by the following method: First, at the same time that the coating composition of the present invention is applied to the object to be coated, the mass (WJ is measured in advance). The coating composition of the present invention is also coated on the aluminum foil, and preheating is performed as necessary. After that, the aluminum foil is collected immediately before the water-based second colored paint (B) is applied to the object to be coated, and its mass (W ₂ ) is measured. Next, the collected aluminum foil is dried at 110 ° C. for 60 minutes, allowed to cool to room temperature in a desiccator, and then the mass (W ₃ ) of the aluminum foil is measured. Find the rate.

Solid content (mass%) = {(W ₃ -W,) / (W ₂ -W _x )} X 1 0 0

The gel fraction of the first colored coating film can be measured by the following method: First, at the same time that the coating composition of the present invention is applied to an article to be coated, the coating composition of the present invention is also applied to a polypropylene plate. After the composition is applied and preheated as necessary, the polypropylene plate is recovered just before the aqueous second colored paint (B) is applied to the article to be coated. The first colored coating film was collected and the mass (W _a ) was measured. After that, the coating film was put in a mesh container made of 20-mesh stainless steel, extracted while refluxing in aceton heated to 64 ° C. for 5 hours, and dried at 110 ° C. for 60 minutes. after the coating mass (W _b) was measured, insoluble coating film residual ratio obtained according to the following equation (mass. / ₀₎ and the gel fraction.

Gel fraction (mass%) = (W _b / W _a ) X 1 0 0

 As the water-based second colored paint (B), for example, those known per se that are usually used in the coating of automobile bodies can be used. Specifically, for example, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin, or an epoxy resin having a crosslinkable functional group such as a carboxyl group or a hydroxyl group, and a polyisocyanate that may be blocked. It is possible to use a compound obtained by dissolving or dispersing a crosslinking agent such as a compound, a melamine resin or a urea resin in water together with a pigment or other additives. Of these, a thermosetting water-based paint comprising a hydroxyl group-containing resin and a melamine resin is preferable.

As the pigment, in addition to the colored pigment and extender pigment exemplified in the description of the coating composition of the present invention, it is possible to use a glitter pigment, etc. By using the glitter pigment as at least a part of the pigment component, A metallic or pearly coating can be formed. Examples of bright pigments include non-leafing or leafing aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, aluminum oxide, mica, titanium oxide and iron oxide. And mica coated with coated aluminum oxide, titanium oxide and iron oxide. Among these, it is preferable to use aluminum, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, mica coated with titanium oxide or iron oxide, and aluminum is particularly preferable. ,. The above luster pigments can be used alone or in combination of two or more.

 The glitter pigment is preferably in the form of flakes, has a longitudinal dimension of 1 to 100 μm, particularly 5 to 40 μπι, and a thickness of 0.0 to 5 μπι, particularly 0. A range of 0 0 1-2 μπι is suitable.

 Further, when the water-based second colored paint (含有) contains the above-mentioned glittering pigment, the amount of the glittering pigment is 100 parts by mass of the resin solid content in the water-based second colored paint (Β). As a standard, it is generally preferable to be within the range of 1 to 40 parts by mass, particularly 3 to 30 parts by mass, and more particularly 5 to 20 parts by mass.

The aqueous second colored paint () preferably further contains a hydrophobic solvent. The hydrophobic solvent is an organic solvent having a mass dissolved in 100 g of water at 20 ° C. of 10 g or less, preferably 5 g or less, more preferably 1 g or less. , Rubber volatile oil, Mineralol spirit, Toluol, Xylol, Solvent naphtha and other hydrocarbon solvents; 11 1 hexanol, n 1 otatano 1, 2-techanol, 2-ethino hexanol, n-decanol, Benzylanolenoleol, Ethyleneglycolenomono 2-ethylenohexenole ether, Propyleneglycone Mononol-Ptyletherenole, Dipropyleneglycone Mono n-Butyl ether, Tripropyleneglycolenomono _n -Putinoleenotenole, Propyleneglycenole Mono 2- Ethinole Hexinoreetenore, Propylene Glycolenomonophe Alcohol solvents such as Honoré ether; acetic n- heptyl acetate Isopuchiru acetate Isoamiru, Estenole solvents such as methylamyl acetate and ethylene glycol monobutyl etherate; and ketonic solvents such as methyl Λ ^ isoptinoleketone, cyclohexanone, ethyl n-aminoleketone, and diisobutyl ketone. Can be used alone or in combination of two or more.

As the hydrophobic solvent, an alcohol solvent is preferably used from the viewpoint of smoothness and sharpness of the resulting multilayer coating film. Among them, alcohol solvents having 7 to 14 carbon atoms, such as n-octanol, 2-octanol, 2-ethyl-1-hexanol, ethylene glycolenomono-2-ethylhexyl etherenole, propylene glycolenomono n —Butyl ether, dipropylene glycol mono- _n- butyl ether are particularly preferred.

 When the aqueous second colored paint (B) contains the hydrophobic solvent, the amount of the hydrophobic solvent is generally based on 100 parts by mass of the resin solid content in the aqueous second colored paint (B). The amount can be in the range of 2 to 70 parts by mass, preferably 5 to 50 parts by mass, and more preferably 10 to 40 parts by mass.

 If necessary, the water-based second colored paint (B) can be used for ordinary paints such as curing catalysts, UV absorbers, light stabilizers, antifoaming agents, plasticizers, organic solvents, surface conditioners, and anti-settling agents. Each additive can be contained alone or in combination of two or more.

 The water-based second colored paint (B) can be applied by a method known per se, for example, air spray, airless spray, rotary atomizing coating machine, and the like. Moyore. The coating film thickness can be in the range of usually 5 to 40 μπι, preferably 10 to 30 μm in terms of cured film thickness. Process (3)

 On the coating film of the water-based second colored paint (B) formed as described above, a tarier paint (C) is further applied.

The clear paint (C) is applied from the viewpoint of sagging suppression and smoothness of the resulting coating film. The solid content of the second colored coating film is generally 70 to 100% by mass, particularly 80 to 100% by mass, more particularly 90 to 100% by mass. / ₀ and it is preferable to perform while in the range of, also, from the viewpoint of smoothness of resulting coating film, the gel fraction of the second colored coating film, generally 0-7 0% by weight, in particular 0 It is preferable to carry out the treatment while it is in the range of 0 to 30% by mass, more particularly 1 to 15% by mass. The solid content and the gel fraction of the second colored coating film can be adjusted by, for example, preheating (preheating), air blowing, etc. before applying the tarry paint (C). The preheating is usually performed at a temperature of about 50 ° C. to about 110 ° C. in the drying furnace in which the water-based first colored paint (A) and the water-based second colored paint (B) are applied, preferably about A temperature of 60 to about 90 ° C. for about 30 seconds to about 60 minutes, preferably about 1 to about 15 minutes, more preferably about 2 to about 10 minutes, particularly preferably about 3 to It can be performed by heating directly or indirectly for about 5 minutes, and the air blow is usually applied to the coated surface of the object at room temperature or a temperature of about 25 ° C to about 80 ° C. This can be done by blowing heated air.

The solid content of the second colored coating film can be measured by the following method: First, at the same time that the aqueous second colored paint (B) is applied on the first colored coating film, the mass ( After coating the water-based second colored paint (B) on the aluminum foil that has been measured for W ₄ ), and preheating as necessary, the tariya paint (C) The aluminum foil is collected immediately before the coating is applied, and its mass (W ₅ ) is measured. Next, the collected aluminum foil was dried at 110 ° C for 60 minutes, allowed to cool to room temperature in a desiccator, and then the mass (W ₆ ) of the aluminum foil was measured. Find the rate.

Solid content (mass%) = {(W ₆ -W ₄ ) / (W ₅ -W ₄ )} XI 0 0

Further, the gel fraction of the second colored coating film can be measured by the following method: First, the aqueous second colored paint (B) is coated on the first colored coating film, and at the same time on the polypropylene plate. After applying the water-based second colored paint (B) and preheating as necessary, the polypropylene plate is recovered immediately before the clear paint (C) is applied on the second colored paint film. In addition, The second colored coating film on the polypropylene plate is collected and the mass (W _c ) is measured. Then, the coated film is put into a 20 mesh stainless steel mesh container, extracted while refluxing for 5 hours in a aceton heated to 64 ° C, and dried at 110 ° C for 60 minutes. The coating film mass (W _d ) after measurement is measured, and the insoluble coating film remaining rate (mass%) obtained according to the following formula is defined as the gel fraction.

Gel fraction (mass./.) = (W _d / W _c ) X 1 0 0

 As the talya paint (C), for example, those known per se that are usually used in the painting of automobile bodies can be used. Specifically, for example, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin, an epoxy resin, or a fluororesin having a crosslinkable functional group such as a hydroxyl group, a carboxyl group, an epoxy group, or a silanol group. , Melamine resin, urea resin, polyisocyanate compound which may be blocked, carboxyl group-containing compound or resin, epoxy group-containing compound or resin-containing organic solvent-based thermosetting paint, aqueous heat A curable coating, a thermosetting powder coating, or the like can be used. Among them, a thermosetting paint containing a hydroxyl group-containing acrylic resin and a melamine resin, a thermosetting paint containing a hydroxyl group-containing acryl resin and an optionally blocked polyisocyanate compound, or a carboxyl group-containing resin. And a thermosetting paint comprising an epoxy group-containing resin is particularly preferred.

 The clear paint (C) may be in the form of a two-part paint such as a one-part paint or a two-part urethane resin paint.

 If necessary, the tariya paint (C) can contain coloring pigments, bright pigments, dyes, etc. to the extent that transparency is not hindered. In addition, extender pigments, UV absorbers, antifoaming agents, A sticking agent, an antifungal agent, a surface conditioner and the like can be appropriately contained.

The tariya paint (C) is applied to the coating surface of the water-based second colored paint (B) formed in step (2) by a method known per se, for example, airless spray, air spray, rotary atomizer, etc. It can be painted and electrostatic application may be applied during painting. Talia paint (C) is applied so that the cured film thickness is in the range of 10 to 60 μπι, preferably 25 to 50 μm. can do. Process (4)

 A multi-layer coating film composed of three layers of the first colored coating film, the second colored coating film, and the clear coating film formed as described above can be obtained, for example, by a conventional coating film baking means. Heat for about 20 to about 40 minutes at a temperature of about 80 to about 170 ° C, preferably about 120 to about 160 ° C by hot air heating, infrared heating, high frequency heating, etc. It can be cured simultaneously, and as a result, it is a multi-layer coating film with excellent smoothness and sharpness consisting of three layers of the first colored coating film, the second colored coating film and the talya coating film. Can be formed. Example

 EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited only to these examples. “Parts” and “%” indicate “parts by mass” and “% by mass”. Production of hydroxyl-containing resin (a)

Production example 1

In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and water separator, trimethylolpropane 1 5 3 parts, neopentyl glycol 3 5 2 parts, adipic acid 2 2 8 parts, isophthalic acid 2 9 7 parts and 10 parts of hexahydrophthalic anhydride were added and heated to remove the condensed water produced, and the reaction was carried out at 23 ° C. until the acid value reached 5. 1 0 0 0 (trade name, manufactured by Cosmo Oil Co., Ltd., petroleum aromatic hydrocarbon solvent) = Diluted to a solid content of 60% with a mixed solvent of 50/50 (mass ratio), hydroxyl value 1 A hydroxyl group-containing resin solution (a-1) having 1 8 and a number average molecular weight of 1,900 was obtained. Production Examples 2-5

 In the same manner as in Production Example 1, by reacting monomers having the blending ratios shown in Table 1 below until the acid values shown in Table 1 below are reached, hydroxyl group-containing resin solutions (a-2) to (a-5) are obtained. It was. The acid value, hydroxyl value, and number average molecular weight of each hydroxyl group-containing resin obtained are shown in Table 1 below together with the hydroxyl group-containing resin solution (a-1) obtained in Production Example 1.

 table 1

Production Example 6

In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and water separator, 109 parts of trimethylololepropane, 141 parts of 1,6-hexanediol, 126 parts of hexahydrophthalic anhydride and adipine 120 parts of acid was charged, and the temperature was raised between 160 ° C. and 230 ° C. over 3 hours, followed by condensation at 230 ° C. for 4 hours. Next, in order to add a carboxyl group to the resulting condensation reaction product, 38.3 parts of trimellitic anhydride was further added and reacted at 170 ° C for 3 minutes, and then to 2-ethyl-1-ester. Diluted with xanol (mass soluble in 100 g water at 20 ° C: 0.1 g), acid value 46 mg KOHZg, hydroxyl value 1 S OmgKOHZg Polyester with a solid content of 70% and a number average molecular weight of 1,400 A resin solution (PE 1) was obtained. Production Example 7 Polyester as in Production Example 6 except that the dilute solvent 2-ethylyl-1-hexanol is changed to ethylene glycol mono-n-butyl ether (mass dissolved in 100 g of water at 20 ° C: infinite). A resin (PE2) was obtained. Manufacture of talyl emulsion

Production Example 8,

 In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and dripping device, add 130 parts of deionized water and Aqualon KH-10 (Note 1) 0.52 part, and stir and mix in a nitrogen stream. The temperature was raised to 80 ° C. Next, 1% of the total amount of the following monomer emulsion (1) and 5.3 parts of a 6% ammonium persulfate aqueous solution were introduced into the reaction vessel and maintained at 80 ° C. for 15 minutes. Thereafter, the remaining monomer emulsion (1) was dropped into a reaction vessel maintained at the same temperature over 3 hours, and aged for 1 hour after completion of the dropping. Thereafter, the following monomer emulsion (2) was added dropwise over 1 hour, and after aging for 1 hour, the mixture was cooled to 30 ° C while gradually adding 40 parts of a 5% aqueous solution of dimethylethanol to the reaction vessel. Drained while filtering through a mesh knives cloth, deionized water using an average particle size of 100 nm (sub-mix sized particle size distribution measuring device “C〇ULTER N4” (trade name, manufactured by Beckman Coulter, Inc.) And an acrylic emulsion having an acid value of 33 mgKOHZg, a hydroxyl value of 25 mgK0HZg, and a solid content concentration of 30% was obtained.

 (Note 1) Aqualon KH-10: Polyoxyethylene alkyl ether sulfate ester rumonmonium salt: 97% active ingredient manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

 Monomer emulsion (1): 42 parts of deionized water, Aqualon KH—10 0.72 parts, 2.1 parts of arylmethacrylate, 2.8 parts of styrene, 16 · 1 咅 of methylmethacrylate, 28 parts of ethylacrylate 21 parts of n-butyl acrylate was mixed and stirred to obtain a monomer monoemulsion (1).

Monomer emulsion (2): Deionized water 18 parts, Aqualon KH-10 0.13 parts, Ammonium persulfate 0 · 03 parts, Methacrylic acid 5.1 parts, 2-Hydroxychetyl acrylate 5.1 parts, Styrene 3 parts, Methyl methacrylate 6 parts, Ethyl acrylate 1. 8 parts and η_Ptyl attaly 9 parts of the rate was mixed and stirred to obtain a monomer emulsion (2). Production example of glitter pigment concentrate

Production Example 9

Put 35 parts ethylene ethylene glycol mono _η -butyl ether in a stirring and mixing vessel, and make 19 parts of aluminum pigment paste “GX-180Α” (trade name, manufactured by Asahi Kasei Metals Co., Ltd., metal content 74%), containing phosphate groups 8 parts of resin solution (Note 2) and 0-2 parts of 2- (dimethylamino) ethanol were mixed uniformly to obtain a bright pigment concentrate.

 (Note 2) Phosphate group-containing resin solution: In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and dropping device, a mixed solvent of 27.5 parts of methoxypropanol and 27.5 parts of isobutanol And heated to 110 ° C, 25 parts of styrene, 27.5 parts of n-butyl methacrylate, “Isostearyl acrylate” (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd., branched higher alkyl acrylate) 20 Part, 4-hydroxypropyl acrylate 7.5 parts, phosphate group-containing polymerizable monomer (Note 3) 15 parts, 2-methacryloylchuccino rare acid phosphate 12.5 parts, isoptanol Mix of 4 parts of t-butyl peroxy tanoate 12 1. Add 5 parts to the above mixed solvent over 4 hours, then add 0.5 part of t-butyl peroxy tanoate and 20 parts of isopropanol. The resulting mixture was added dropwise over 1 hour. Thereafter, the mixture was aged and stirred for 1 hour to obtain a phosphate group-containing resin solution having a solid concentration of 50%. This resin had an acid value of 83 mgKOHZg, a hydroxyl value of 29 mgKOHZg, and a weight average molecular weight of 10,000.

(Note 3) Phosphoric acid group-containing polymerizable monomer: In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux cooler and dripping device, 57.5 parts of monoptyl phosphoric acid and Isov 'After adding 41 parts of ethanol and raising the temperature to 90 ° C, 42.5 parts of glycidyl methacrylate was added dropwise over 2 hours, followed by stirring and aging for another hour. Thereafter, 59 parts of isopropanol was added to obtain a phosphate group-containing polymerizable monomer solution having a solid content concentration of 50%. The acid value due to the phosphoric acid group was 285 mg KOH / g. Production of first colored paint (A)

 Example:! To 24, Comparative Examples 1 to 3

 Any of the hydroxyl group-containing resin solutions (a-1) to (a-5) obtained in the above Production Examples 1 to 5, any of the following polyisocyanate compounds (b_l) to (b-3), Polyol compound (c 1) to (c 1 6), silicon dioxide (d-1) to (d-3) below, pigment (P-1) to (P-3) below Cymel 325 (trade name, manufactured by Nihon Cytec Industries, Inc., melamine resin, solid content 80%), TPA-B 80 X (trade name, manufactured by Asahi Kasei Chemical Co., Ltd., methyl ethyl chloride of hexamethylene diisocyanate) Simpeloc material, solid content 80%) and diptyltin diacetate were mixed with stirring using a disper at the blending ratio shown in Table 2 below to make a paint, and the first colored paint (A-1) to (A —27) The blending ratio of the first colored paint shown in Table 2 is the solid content mass ratio of each component. In addition, when blending the pigment component, add 42 parts of the hydroxyl group-containing resin solution in the first colored paint (25 parts of resin solids) and 7 parts of xylene to the amount of pigment shown in Table 2 and mix. Paint Shaker The mixture was dispersed for 30 minutes to obtain a pigment dispersion paste, which was then stirred and mixed with other components.

The first colored paint can be further added by adding a mixed solvent of xylene / Suzo Monore 1000 (trade name, Cosmo Oil, petroleum aromatic hydrocarbon solvent) = 50/50 (mass ratio). Using a Ford Cup No. 4, the viscosity was adjusted to 20 seconds at 20 ° C. The polyisocyanate compounds (b-1) to (b-3) in Table 2 below, The compounds (c-1) to (c_6), silicon dioxide (d-1) to (d-3), and pigments (P-1) to (P-3) are as follows.

 Polyisocyanate (b_l): Sumijeu Nore N3300 (trade name, manufactured by Sumika Bayer Urethane Co., Ltd., isocyanurate of hexamethylene diisocyanate, solid content 100%, NCO content 21.8%).

 Polyisocyanate (b—2): Dice Module N 340◦ (trade name, manufactured by Sumika Bayer-Luretan, uretdione of hexamethylene diisocyanate, solid content 100%, N CO content 21.8% )

 Polyisocyanate (b-3): Dice module Z 4470 (trade name, manufactured by Sumika Bayer Urethane Co., Ltd., Isophoronate of isophorone disiocyanate, solid content 70%, NC 0 content 11.7%) .

 Polyol compound (c—1): Kuraray Polyol P-510 (trade name, manufactured by Kuraren clay, polyester polyol, number average molecular weight 500).

 Polyol compound (c 1 2): Kuraray polyether P-101 1 (trade name, manufactured by Kuraray Co., Ltd., polyester polyol, number average molecular weight 1,000).

 Polyol compound (c_3): Kuraray Polyether F-2010 (trade name, manufactured by Kuraray Co., Ltd., polyester polyol, number average molecular weight 2,000).

 Polyol compound (c-4): Ade force polyether P_1000 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd., polyether polyol, number average molecular weight 1,000).

 Polyol compound (c 1 5): UH-CARB 50 (trade name, manufactured by Ube Industries, polycarbonate polyol, number average molecular weight 500).

 Polyol compound (c_6): T-56 50 J (trade name, manufactured by Asahi Kasei Chemicals Corporation, polycarbonate polyol, number average molecular weight 800).

Silicon dioxide (d_l): AERO SIL 200 (trade name, manufactured by Nippon Aerosil Co., Ltd., carbon content 0 mass%). ' Silicon dioxide (d-2): AEROS ILR-972 (trade name, Nippon Aerosil Co., Ltd., carbon content 0.8 mass%).

 Silicon dioxide (d-3): AEROS ILR-1104 (trade name, manufactured by Nippon Aerosil Co., Ltd., carbon content 1.1 mass%).

Pigment (P-1): JR-806 (trade name, manufactured by Tika, rutile titanium dioxide). Pigment (P-2): MI CRO ACE S-3 (trade name, manufactured by Nippon Talc Co., Ltd.). Pigment (P-3): Carbon MA-100 (trade name, manufactured by Mitsubishi Chemical Corporation, carbon black). In addition, the obtained first colored paints (A-1) to (A-27) were coated on a polypropylene plate so as to have a cured film thickness of 30; um, and heated at 70 for 5 minutes. gel fraction (G _7.), and curing S莫厚on a polypropylene plate was applied to a 30 μπι, the gel fraction of the coating film after heating for 10 minutes at 90 ° C (G _9.) The measurement results are shown in Table 2.

Table 2

Manufacture of water-based second colored paint (B)

Production Example 10

57 parts of the polyester resin solution (PE 1) obtained in Production Example 6, 100 parts of acrylic emulsion obtained in Production Example 8, 62 parts of the bright pigment concentrate obtained in Production Example 9 and “Cymel 325” (trade name, Japan) (Made by Cytec Industries, melamine resin, solid content 80%) 37. Mix 5 parts uniformly, and add deionized water and 2- (dimethylamino) ethanol to a pH of 8.0 and solid content of 23%. An aqueous second colored paint (B-1) was obtained. Production example 1 1

 Except for changing 57 parts of the polyester resin solution (PE 1) to 57 parts of the polyester resin solution (PE2) obtained in Production Example IV, the second water-based second colored paint (B-2) Got. Coating method

 First colored paints (A— :!) to (A- 27) obtained in Examples 1 to 24 and Comparative Examples 1 to 3, and aqueous second colored paints obtained in Production Examples 10 and 11 ( Using B-1) and (B-2), test coated plates were prepared and evaluated as follows.

 (Preparation of test article)

 Electron GT-1 0 (trade name, manufactured by Kansai Paint Co., Ltd., cationic electrodeposition paint) is electrodeposited onto a cold-rolled steel sheet that has been subjected to zinc phosphate conversion treatment to a cured film thickness of 20 μπι. It was cured by heating at 70 ° C for 30 minutes to obtain a test article. Example 25

In a coating environment at a temperature of 23 ° C and a humidity of 75%, the first colored paint (A-1) obtained in Example 1 above was applied to the above-mentioned test object, respectively, using a rotary atomizing coating machine. Using this coating, the film thickness was 30 μπι and the coating was preheated at 70 ° C for 5 minutes. Next, the water-based second colored paint (B-1) obtained in Production Example 10 is applied on the first colored coating film using a rotary atomizing coating machine so as to have a dry film thickness of 15 111. And preheated at 80 for 10 minutes. Next, on the second colored coating film, MAJIKRON KI NO-1 210 (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin-based solvent-type top coat, hereinafter referred to as “clear paint (C 1)”) ) Was coated so that the thickness of the curing month was 40 μπι, and left for 7 minutes, then heated at 140 ° C. for 30 minutes, and the above first colored coating film, second colored coating film and clear coating film were At the same time, it was cured to produce a test coated plate. Examples 26-49, Comparative Examples 4-6

 In Example 25, the first colored paint (A-1) obtained in Example 1 was changed to the first colored paint (A-2) to (A-27) shown in Table 3 and obtained in Production Example 10. Example 25 is the same as Example 25 except that the water-based second colored paint (B-1) is changed to the water-based second colored paint (B-1) or the water-based second colored paint (B-2) obtained in Production Example 11. A test coated plate was produced in the same manner. Each test plate obtained in Examples 25 to 49 and Comparative Examples 4 to 6 was evaluated by the following test method. Table 3 shows the evaluation results. (Test method)

 Smoothness: Evaluated by using the Long Wa Ve (LW) value measured by Wave S can (trade name, manufactured by BYK Gardner). The Long Wave (LW) value is an index of the amplitude of the surface roughness at a wavelength of about 1.2 to 12 mm. The smaller the measured value, the higher the smoothness of the coated surface.

Vividness: Evaluated using the Short Wave (SW) value measured by the above Wave Scan. The Short Wave (SW) value is an indicator of the amplitude of the surface roughness at a wavelength of about 3 to 1.2 mm. The smaller the measured value, the higher the clearness of the paint surface.

Table 3

Claims

The scope of the claims

1. The following steps (1) to (4):

 (1) A first colored paint (A) is applied to the object to be coated to form a first colored paint film. (2) A water-based second colored paint (B) is formed on the formed first colored paint film. ) To form a second colored coating film,

 (3) On the second colored coating film to be formed, paint the Talia paint (C) to form a Talia paint film.

 (4) Baking and hardening the first colored coating film, the second colored coating film, and the talya coating film to be formed at the same time.

A coating composition for use as the first colored paint (A) in the method of forming a multilayer coating film by using an acid value of 15 mg KOHZg or less, based on 100 parts by mass of resin solids in the coating composition A coating composition comprising 30 to 95 parts by mass of a hydroxyl group-containing resin (a) having 5 to 70 parts by mass of a polyisocyanate compound (b).

2. The coating composition according to claim 1, wherein the hydroxyl group-containing resin (a) has an acid value within a range of 1 to 12 mgKH / g.

3. Hydroxyl-containing tree month effect (a) Force Sl Hydroxyl-containing polyester resin having an acid value of 5 mgK ○ HZg or less and a hydroxyl value in the range of 50 to 200 mg KOHZg or an acid value of 15 mgK OH / g or less and 20 to 20 Omg 2. The coating composition according to claim 1, which is a hydroxyl group-containing acryl resin having a hydroxyl value within the range of KOHZg.

4. The coating composition according to claim 1, wherein the coating composition contains 40 to 80 parts by mass of the hydroxyl group-containing resin (a) based on 100 parts by mass of the resin solid content in the coating composition.

5. The coating composition further contains 1 to 50 parts by mass of a polyol compound (c) having a number average molecular weight in the range of 100 to 2,000, based on 100 parts by mass of the resin solid content in the coating composition. The coating composition according to claim 1.

6. The coating composition according to claim 5, wherein the polyol compound (c) ′ is selected from the group consisting of a polyester polyol and a polycarbonate polyol.

7. The coating composition according to claim 1, wherein the coating composition contains 10 to 50 parts by mass of the polyisocyanate compound (b) based on 100 parts by mass of the resin solid content in the coating composition.

8. The coating composition according to claim 1, wherein the coating composition further contains 0.1 to 5 parts by mass of silicon dioxide (d) based on 100 parts by mass of the resin solid content in the coating composition. .

9. The coating composition according to claim 8, wherein the silicon dioxide (d) is silicon dioxide having a carbon content of 1.0% by mass or less.

10. The coating composition has an acid value in the range of 3 to 15 mg KOH / g and a number average molecular weight of 1,000 to 10,000, 00, based on 100 parts by mass of resin solid content in the coating composition. 30 to 95 parts by mass of a hydroxyl group-containing resin (a) in the range of 5 to 40 parts by mass of the polyisocyanate compound (b) and a polyol having a number average molecular weight in the range of 400 to 700 The coating composition according to claim 1, which contains 1 to 30 parts by mass of the compound (c).

1 1. The coating composition is applied so that the cured film thickness is 30 ^ m. The coating was coated so that the gel fraction (G _7. ) Of the coating film after heating at 0 ° C for 5 minutes was in the range of 0 to 20% by mass and the cured film thickness was 30 Aim. The coating composition according to claim 1, wherein the gel fraction (G ₉₀ ) of the coating film after heating at ° C for 10 minutes is in the range of 30 to 100% by mass.

1 2. The following steps (1) to (4):

 (1) The first colored paint (A) is applied on the object to be coated to form the first colored coating film.

(2) A water-based second colored paint (B) is applied on the formed first colored coating film to form a second colored coating film.

 (3) A clear paint (C) is applied on the second colored paint film to be formed to form a clear paint film.

 (4) The first colored coating film, the second colored coating film and the clear coating film to be formed are simultaneously baked and cured.

In the method of forming a multi-layer coating film by water, as the first colored paint (A), water having an acid value of 15 mgK0H / g or less, based on 10 parts by mass of resin solid content in the paint composition. A method for forming a multilayer coating film, comprising using a coating composition comprising 30 to 95 parts by mass of an acid group-containing resin (a) and 5 to 70 parts by mass of a polyisocyanate compound (b).

1 3. It has an acid value of 1 SmgKOH / g or less based on 100 parts by mass of the resin solid content in the paint composition as the first colored paint (A) in the method described in claim 1 Use of a coating composition comprising 30 to 95 parts by mass of a hydroxyl group-containing resin (a) and 5 to 70 parts by mass of a polyisocyanate compound (b).

14. An article having a multilayer coating film formed by the method according to claim 12.