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WO2010095541A1 - Composition de revêtement à base d'eau et procédé de formation d'un film de revêtement multicouche - Google Patents

Composition de revêtement à base d'eau et procédé de formation d'un film de revêtement multicouche Download PDF

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Publication number
WO2010095541A1
WO2010095541A1 PCT/JP2010/051899 JP2010051899W WO2010095541A1 WO 2010095541 A1 WO2010095541 A1 WO 2010095541A1 JP 2010051899 W JP2010051899 W JP 2010051899W WO 2010095541 A1 WO2010095541 A1 WO 2010095541A1
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WO
WIPO (PCT)
Prior art keywords
coating film
water
mass
group
acid
Prior art date
Application number
PCT/JP2010/051899
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English (en)
Japanese (ja)
Inventor
博視 北川
宗寛 中田
大輔 高山
達也 東
Original Assignee
関西ペイント株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2009149567A external-priority patent/JP5451207B2/ja
Priority claimed from JP2009172644A external-priority patent/JP5547434B2/ja
Application filed by 関西ペイント株式会社 filed Critical 関西ペイント株式会社
Priority to CA 2751955 priority Critical patent/CA2751955C/fr
Priority to CN201080008190.1A priority patent/CN102317386B/zh
Priority to US13/201,953 priority patent/US8993673B2/en
Publication of WO2010095541A1 publication Critical patent/WO2010095541A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • C08G18/4205—Polycondensates having carboxylic or carbonic ester groups in the main chain containing cyclic groups
    • C08G18/4208—Polycondensates having carboxylic or carbonic ester groups in the main chain containing cyclic groups containing aromatic groups
    • C08G18/4211—Polycondensates having carboxylic or carbonic ester groups in the main chain containing cyclic groups containing aromatic groups derived from aromatic dicarboxylic acids and dialcohols
    • C08G18/4219—Polycondensates having carboxylic or carbonic ester groups in the main chain containing cyclic groups containing aromatic groups derived from aromatic dicarboxylic acids and dialcohols from aromatic dicarboxylic acids and dialcohols in combination with polycarboxylic acids and/or polyhydroxy compounds which are at least trifunctional
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/50—Multilayers
    • B05D7/52—Two layers
    • B05D7/53—Base coat plus clear coat type
    • B05D7/532—Base coat plus clear coat type the two layers being cured or baked together, i.e. wet on wet
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/0804—Manufacture of polymers containing ionic or ionogenic groups
    • C08G18/0819—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups
    • C08G18/0823—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups containing carboxylate salt groups or groups forming them
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/2805—Compounds having only one group containing active hydrogen
    • C08G18/2815—Monohydroxy compounds
    • C08G18/283—Compounds containing ether groups, e.g. oxyalkylated monohydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
    • C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
    • C08G18/625—Polymers of alpha-beta ethylenically unsaturated carboxylic acids; hydrolyzed polymers of esters of these acids
    • C08G18/6254—Polymers of alpha-beta ethylenically unsaturated carboxylic acids and of esters of these acids containing hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
    • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
    • C08G18/6633—Compounds of group C08G18/42
    • C08G18/6659—Compounds of group C08G18/42 with compounds of group C08G18/34
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
    • C08G18/75—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic
    • C08G18/758—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing two or more cycloaliphatic rings
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/80—Masked polyisocyanates
    • C08G18/8061—Masked polyisocyanates masked with compounds having only one group containing active hydrogen
    • C08G18/8093—Compounds containing active methylene groups
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/63—Additives non-macromolecular organic

Definitions

  • the present invention relates to a water-based coating composition excellent in finished appearance and a method for forming a multilayer coating film.
  • the outer plate of an automobile body is usually coated with a multilayer coating consisting of a primer coating, an intermediate coating, and a top coating with a cationic electrodeposition coating for the purpose of providing corrosion protection and aesthetics. From the viewpoint of reduction, water-based coatings are also being promoted in intermediate coatings and top coatings.
  • the conventional water-based paint has a problem that the finished appearance of the coating film is generally insufficient as compared with the solvent-type paint because the main solvent is water.
  • Patent Document 1 discloses a specific acrylic resin and / or polyester resin as an aqueous coating composition that provides a high-appearance coating film that has good coating workability (boil resistance, sagging resistance) and excellent smoothness.
  • a water-based paint mainly composed of a specific polycarbonate resin and a curing agent is disclosed.
  • Patent Document 2 discloses a water-based paint mainly composed of a specific acrylic resin and / or polyester resin, a specific polycarbonate resin, a curing agent, and specific resin particles.
  • the coating film obtained by the water-based paint sometimes has poor finished appearance such as smoothness.
  • the solvent contained in the clear coating penetrates and swells the intermediate coating film and the base coating film, thereby producing fine skin.
  • the smoothness of the resulting multilayer coating film was lowered, the finished appearance was insufficient, and / or the bell washability of the aqueous intermediate coating composition was sometimes inferior.
  • An object of the present invention is to provide a water-based paint composition excellent in finished appearance and bell washability, and sequentially apply a water-based first colored paint, a water-based second colored paint, and a clear paint on the object to be coated.
  • Another object of the present invention is to provide a method capable of forming a multilayer coating film excellent in smoothness in a three-coat one-bake method in which the obtained three-layer multilayer coating film is simultaneously heat-cured.
  • a water-based coating composition characterized by containing a urethane resin emulsion (C) having a weight average molecular weight of 2,000 to 50,000 obtained from In a three-coat one-bake system in which a water-based first colored paint, a water-based second colored paint, and a clear paint are sequentially applied, and the resulting three-layered multi-layer coating is simultaneously heated and cured, the paint composition is used as the water-based first colored paint.
  • C urethane resin emulsion
  • the present invention relates to a urethane resin emulsion (C) having a weight average molecular weight of 2,000 to 50,000 which is produced from an acrylic resin (A), a curing agent (B), and a component containing a polyisocyanate component and a polyol component.
  • Containing The polyisocyanate component contains an alicyclic diisocyanate, and the polyol component contains a polycarbonate diol in an amount of 50% by mass or more of the total amount of the polyol component.
  • Step (1) A step of forming the first colored coating film by coating the aqueous first colored paint (X)
  • Step (2) A step of forming a second colored coating film by applying an aqueous second colored coating material (Y) on the first colored coating film formed in the step (1).
  • Step (3) a step of applying a clear paint (Z) on the second colored coating film formed in the step (2) to form a clear coating film
  • a step (4) the step (1).
  • the aqueous coating composition of the present invention comprises a urethane resin emulsion obtained from a component comprising a polyisocyanate component containing an alicyclic diisocyanate and a polyol component containing polycarbonate diol in an amount of 50% by mass or more of the total amount of the polyol component.
  • the main feature is to include.
  • the urethane resin emulsion is contained as an aqueous first colored coating material for forming the first colored coating film.
  • the first colored coating film and the second colored coating film can be prevented from being mixed by suppressing the swelling of the first colored coating film with water and the organic solvent. it can.
  • the 1st colored coating film and 2nd colored coating film which cause the finishing external appearance defect by the penetration
  • aqueous coating composition and the method for forming a multilayer coating film of the present invention it is possible to obtain an effect that it is possible to obtain a multilayer coating film having excellent bell washability and excellent smoothness. .
  • Aqueous paint composition The aqueous paint composition of the present invention comprises an acrylic resin (A), a curing agent (B), and a urethane resin emulsion having a weight average molecular weight of 2,000 to 50,000 produced using a polyisocyanate component and a polyol component as raw materials.
  • the polyisocyanate component contains an alicyclic diisocyanate, and the polyol component contains a polycarbonate diol in an amount of 50% by mass or more of the total amount of the polyol component.
  • Acrylic resin (A) As the acrylic resin (A), a water-soluble or water-dispersible acrylic resin known per se that has been conventionally used in water-based paints can be used.
  • the acrylic resin (A) usually has a crosslinkable functional group that can react with the curing agent (B) such as a hydroxyl group, a carboxyl group, and an epoxy group. Especially, it is preferable to use a hydroxyl-containing acrylic resin.
  • the acrylic resin (A) can be produced by a method known per se or a method similar thereto.
  • a hydroxyl group-containing acrylic resin is usually prepared by a method known per se, such as an organic solvent, for a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer. It can be produced by copolymerization by a method such as solution polymerization in water or emulsion polymerization in water.
  • the hydroxyl group-containing polymerizable unsaturated monomer is a compound having at least one hydroxyl group and one polymerizable unsaturated bond in one molecule, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( Monoesterified products of (meth) acrylic acid such as (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like and dihydric alcohols having 2 to 8 carbon atoms; the (meth) acrylic acid ⁇ -caprolactone modified product of a monoesterified product of a dihydric alcohol having 2 to 8 carbon atoms; N-hydroxymethyl (meth) acrylamide; allyl alcohol, and further having a polyoxyethylene chain having a hydroxyl group at the molecular end (meta ) Acrylate and the like.
  • (meth) acrylate means “acrylate or methacrylate”.
  • (Meth) acrylic acid means “acrylic acid or methacrylic acid”.
  • (Meth) acryloyl means “acryloyl or methacryloyl”.
  • (Meth) acrylamide means “acrylamide or methacrylamide”.
  • the other polymerizable unsaturated monomer copolymerizable with the said hydroxyl-containing polymerizable unsaturated monomer can be suitably selected and used according to the characteristic desired for a hydroxyl-containing acrylic resin.
  • Specific examples of the monomer are listed in (i) to (xix). Even monomers not listed here may be used as long as they are copolymerizable unsaturated unsaturated monomers. Needless to say. These can be used alone or in combination of two or more.
  • alkyl or cycloalkyl (meth) acrylate for example, 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 (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate: for
  • (Vi) polymerizable unsaturated monomer having an alkoxysilyl group for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, ⁇ - (meth) acryloyloxypropyltrimethoxysilane, ⁇ - ( (Meth) acryloyloxypropyltriethoxysilane and the like.
  • (Vii) Polymerizable unsaturated monomer having a fluorinated alkyl group: for example, perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; fluoroolefin and the like.
  • (Viii) Polymerizable unsaturated monomer having a photopolymerizable functional group such as a maleimide group: those widely known in the art can be used.
  • (Ix) Vinyl compounds: for example, N-vinyl pyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate and the like.
  • Phosphoric acid group-containing polymerizable unsaturated monomer for example, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate, and the like.
  • Carboxy group-containing polymerizable unsaturated monomer for example, (meth) acrylic acid, maleic acid, crotonic acid, ⁇ -carboxyethyl acrylate and the like.
  • Nitrogen-containing polymerizable unsaturated monomers for example, (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N— Dimethylaminopropyl (meth) acrylamide, methylene bis (meth) acrylamide, ethylene bis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, adducts of glycidyl (meth) acrylate and amines.
  • (meth) acrylonitrile for example, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N— Dimethylaminopropyl (meth) acrylamide,
  • (Xiii) polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule: for example, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate etc.
  • Epoxy group-containing polymerizable unsaturated monomer for example, glycidyl (meth) acrylate, ⁇ -methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) ) Acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether and the like.
  • (Xv) (Meth) acrylate having a polyoxyethylene chain whose molecular end is an alkoxy group those widely known in the art can be used.
  • polymerizable unsaturated monomer having a sulfonic acid group for example, 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc .; Sodium salt and ammonium salt.
  • (Xvii) polymerizable unsaturated monomer having a UV-absorbing functional group for example, 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′-methacryloyloxyethylphenyl) -2H-benzotriazole and the like.
  • (Xviii) light-stable polymerizable unsaturated monomer for example, 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, , 6,6-tetramethylpiperidine
  • (Xix) polymerizable unsaturated monomers having a carbonyl group for example, acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrene, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl Methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) and the like.
  • urethane-modified acrylic resin (after-mentioned urethane resin emulsion (after-mentioned) which extended
  • the hydroxyl value of the hydroxyl group-containing acrylic resin (A1) is 1 to 200 mgKOH / g, preferably 2 to 100 mgKOH / g, more preferably 5 to 80 mgKOH / g, from the viewpoints of storage stability and water resistance of the resulting coating film. It is preferable to be within the range.
  • the acid value of the hydroxyl group-containing acrylic resin (A1) is from 0 to 200 mgKOH / g, preferably from 0 to 100 mgKOH / g, more preferably from 0 to 50 mgKOH / g, from the viewpoint of the water resistance of the resulting coating film. It is preferable to be within the range.
  • the weight-average molecular weight of the hydroxyl group-containing acrylic resin (A1) is 2,000 to 5,000,000, preferably 10,000 to 2,000,000 from the viewpoints of the appearance and water resistance of the resulting coating film. It is preferable to be within the range of 000.
  • the number average molecular weight and the weight average molecular weight are converted values using polystyrene having a known molecular weight as a standard substance, measured using a gel permeation chromatograph and using tetrahydrofuran as a solvent.
  • water-dispersible acrylic resin particles synthesized by emulsion polymerization in water can be suitably used as the acrylic resin.
  • Water-dispersible acrylic resin particles can be obtained, for example, by subjecting a polymerizable unsaturated monomer typified by a vinyl monomer to emulsion polymerization using a radical polymerization initiator in the presence of a dispersion stabilizer such as a surfactant. Can do.
  • Examples of the polymerizable unsaturated monomer to be emulsion-polymerized include a carboxyl group-containing polymerizable unsaturated monomer (M-1), a hydroxyl group-containing polymerizable unsaturated monomer (M-2), and other polymerizable unsaturated monomers (M-3). Examples thereof include a polyvinyl compound (M-4) having two or more polymerizable unsaturated groups in one molecule.
  • the carboxyl group-containing polymerizable unsaturated monomer (M-1) is a compound having one or more carboxyl groups and one polymerizable unsaturated group in one molecule, such as acrylic acid, methacrylic acid, crotonic acid, Maleic acid, itaconic acid and the like can be mentioned. Furthermore, an acid anhydride of these compounds, a monocarboxylic acid obtained by half-esterification of the acid anhydride, and the like are also included in the monomer (M-1) in the present specification.
  • the carboxyl group-containing polymerizable unsaturated monomer is a monomer for introducing a carboxyl group in order to impart water dispersibility to the water dispersible acrylic resin particles.
  • These carboxyl group-containing polymerizable unsaturated monomers (M-1) can be used alone or in combination of two or more.
  • the hydroxyl group-containing polymerizable unsaturated monomer (M-2) is a compound having one hydroxyl group and one polymerizable unsaturated group in one molecule, and this hydroxyl group can act as a functional group that reacts with a crosslinking agent. it can.
  • the monomer is preferably a monoester product of acrylic acid or methacrylic acid and a dihydric alcohol having 2 to 10 carbon atoms, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, Hydroxyl group-containing acrylate monomers such as 3-hydroxypropyl acrylate and 4-hydroxybutyl acrylate, hydroxyl group-containing methacrylate monomers such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate and 4-hydroxybutyl methacrylate, Examples thereof include N-methylol acrylamide and N-methylol methacrylamide.
  • hydroxyl group-containing polymerizable unsaturated monomers (M-2) can be used alone or in combination of two or more.
  • the other polymerizable unsaturated monomer (M-3) is a compound having one polymerizable unsaturated group in one molecule other than the monomers (M-1) and (M-2). Examples are listed in the following (1) to (8).
  • Alkyl (meth) acrylate monomer (specifically, monoesterified product of acrylic acid or methacrylic acid and monohydric alcohol having 1 to 20 carbon atoms): for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate Propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate and the like.
  • an alkyl (meth) acrylate monomer having an alkyl group with 4 to 14 carbon atoms, preferably 4 to 8 carbon atoms is preferable from the viewpoint of smoothness of the resulting multilayer coating film.
  • the copolymerization amount is 30 to 80% by mass based on the total amount of polymerizable unsaturated monomers. Is preferred.
  • Aromatic vinyl monomers for example, styrene, ⁇ -methylstyrene, vinyltoluene and the like.
  • Glycidyl group-containing vinyl monomer a compound having one or more glycidyl groups and one polymerizable unsaturated bond in a molecule, specifically, glycidyl acrylate, glycidyl methacrylate, and the like.
  • Nitrogen-containing alkyl (having 1 to 20 carbon atoms) (meth) acrylate for example, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and the like.
  • Polymerizable unsaturated group-containing amide compound a compound having one or more amide groups and one polymerizable unsaturated bond in one molecule, such as acrylamide, methacrylamide, dimethylacrylamide, N, N-dimethylpropylacrylamide, N-butoxymethylacrylamide, diacetone acrylamide and the like.
  • Polymerizable unsaturated group-containing nitrile compound for example, acrylonitrile, methacrylonitrile and the like.
  • Diene compounds for example, butadiene, isoprene and the like.
  • Vinyl compounds For example, vinyl acetate, vinyl propionate, vinyl chloride and the like.
  • the polyvinyl compound (M-4) is a compound having two or more polymerizable unsaturated groups in one molecule, such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate. Examples include methacrylate, 1,6-hexanediol diacrylate, allyl methacrylate, allyl acrylate, divinylbenzene, trimethylolpropane triacrylate, methylene bis (meth) acrylamide, and ethylene bis (meth) acrylamide.
  • the polyvinyl compound (M-4) does not include the diene compound.
  • These polyvinyl compounds (M-4) can be used alone or in combination of two or more.
  • the mixing ratio of the polymerizable unsaturated monomer in the water-dispersible acrylic resin particles is not particularly limited, but is preferably as follows.
  • the carboxyl group-containing polymerizable unsaturated monomer (M-1) is preferably 0.1 to 25 based on the total amount of the polymerizable unsaturated monomer from the viewpoint of water dispersibility and water resistance of the polymer particles. % By weight, more preferably 0.1 to 10% by weight, and still more preferably 0.5 to 5% by weight.
  • the hydroxyl group-containing polymerizable unsaturated monomer (M-2) varies depending on the type and amount of the curing agent used, but from the viewpoint of curability and water resistance of the coating film, etc., based on the total amount of the polymerizable unsaturated monomer.
  • 0.1 to 40% by mass, more preferably 0.1 to 25% by mass, and still more preferably 1 to 10% by mass can be used.
  • the other polymerizable unsaturated monomer (M-3) can be appropriately used so that the total amount of the polymerizable unsaturated monomer is 100% by mass, but is preferably based on the total amount of the polymerizable unsaturated monomer.
  • 20 to 99.8% by mass more preferably 30 to 80% by mass.
  • the polyvinyl compound (M-4) is used as necessary, but the blending ratio is 0 to 15% by weight, preferably 0 to 10% by weight, based on the total amount of the polymerizable unsaturated monomer, The content is preferably 0 to 5% by mass.
  • the dispersion stabilizer examples include an anionic emulsifier, a nonionic emulsifier, and an amphoteric ion emulsifier.
  • Specific examples of the anionic emulsifier include fatty acids, alkyl sulfate esters, alkylbenzene sulfonates, and alkyl phosphates.
  • Nonionic emulsifiers include, for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene compounds, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl amines, alkyl alkanolamides, and the like. Can do.
  • Examples of the zwitterionic emulsifier include alkylbedine.
  • a reactive emulsifier can be particularly preferably used from the viewpoint of coating performance such as water resistance of the multilayer coating and reduction of residual monomer for environmental measures.
  • the reactive emulsifier is an emulsifier having radical reactivity with a vinyl monomer, in other words, a surfactant having a polymerizable unsaturated group in one molecule.
  • the reactive emulsifier include Eleminol JS-1, Eleminol JS-2 (manufactured by Sanyo Chemical Co., Ltd.), S-120, S-180A, S-180, Latemul PD-104, Latemuru PD-420, Latemuru PD- 430S, Latemul PD-450 (manufactured by Kao Corporation), Aqualon HS-10, Aqualon KH-10 (manufactured by Daiichi Kogyo Seiyaku), Adekaria soap SE-10N, Adekaria soap SE-20N, Adekaria soap SR-1025 ADEKA rear soap ER-10, ADEKA rear soap ER-20, ADEKA rear soap ER-30, ADEKA rear soap ER-40 (Asahi Denka Co., Ltd.), ANTOX MS-60 (manufactured by Nippon Emulsifier Co., Ltd.), etc. it can.
  • the dispersion stabilizer such as the above emulsifier can be used alone or in combination of two or more in the emulsion polymerization reaction.
  • the amount of the dispersion stabilizer used is in the range of 0.1 to 10% by mass, particularly 1 to 7.5% by mass, and more particularly 1.5 to 6% by mass with respect to the water-dispersible acrylic resin particles produced. Preferably there is.
  • the amount of the reactive emulsifier used is 0.1 to 10% by weight, particularly 1.5 to 7%, based on the water-dispersible acrylic polymer particles produced. It is preferably in the range of 5% by weight, more particularly 2 to 6% by weight.
  • radical polymerization initiator examples include peroxides represented by ammonium persulfate, potassium persulfate, ammonium peroxide, and the like, and these peroxides and sodium bisulfite, sodium thiosulfate, Rongalite, ascorbic acid, and the like.
  • redox initiators combined with reducing agents, 2,2'-azobisisobutyronitrile, 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis [2-methyl- And azo compounds such as N- (2-hydroxyethyl) -propionamide]. Of these, azo compounds are preferred.
  • the amount of the radical polymerization initiator is usually 0.1 to 5.0% by mass, preferably 0.1 to 3.3% by weight based on the total solid content of the polymerizable unsaturated monomer forming the water-dispersible acrylic resin particles. It is suitable to be in the range of 0% by mass, more preferably 1 to 3.0% by mass.
  • the concentration of all radically polymerizable unsaturated monomers in the emulsion polymerization reaction is usually in the range of 0.1 to 60% by mass, preferably 0.5 to 50% by mass, more preferably 1.0 to 50% by mass. It is suitable to be within.
  • the reaction temperature during emulsion polymerization varies depending on the radical polymerization initiator to be used, but is usually 40 to 100 ° C, preferably 50 to 90 ° C, and more preferably 60 to 80 ° C.
  • the reaction time is usually 3 to 24 hours, preferably 5 to 20 hours, more preferably 7 to 16 hours.
  • the water-dispersible acrylic resin particles may have a normal uniform structure or a multilayer structure such as a core / shell structure.
  • the water-dispersible acrylic resin particles having a core / shell structure for example, initially contain no or almost no carboxyl group-containing polymerizable unsaturated monomer (M-1) (for example, The content of the carboxyl group-containing polymerizable unsaturated monomer (M-1) is 0 to 1% by mass with respect to the total amount of monomers forming the core component). Then, as a shell part, it can be obtained by adding a polymerizable unsaturated monomer component containing a large amount of a carboxyl group-containing polymerizable unsaturated monomer (M-1) and emulsion polymerization.
  • M-1 carboxyl group-containing polymerizable unsaturated monomer
  • the bond between the core part and the shell part is, for example, polymerizable including a carboxyl group-containing polymerizable unsaturated monomer (M-1) in a polymerizable unsaturated bond such as allyl acrylate or allyl methacrylate remaining on the surface of the core part. It can be carried out by copolymerizing unsaturated monomer components.
  • M-1 carboxyl group-containing polymerizable unsaturated monomer
  • the water-dispersible acrylic resin particles have a hydroxyl group in the range of 0 to 150 mgKOH / g, preferably 5 to 100 mgKOH / g, more preferably 10 to 50 mgKOH / g, from the viewpoint of water resistance and curability of the resulting coating film.
  • the water-dispersible acrylic resin particles are used in the range of 0 to 100 mgKOH / g, preferably 0 to 50 mgKOH / g, more preferably 0 to 35 mgKOH / g, from the viewpoints of storage stability and water resistance of the resulting coating film.
  • the acid value can be within.
  • the water-dispersible acrylic resin particles are average particles in the range of 10 to 500 nm, preferably 20 to 300 nm, more preferably 40 to 200 nm, from the viewpoint of dispersion stability of the particles and smoothness when formed into a coating film.
  • Can have a diameter.
  • the average particle diameter of the water-dispersible acrylic resin particles is a value measured at 20 ° C. after being diluted with deionized water by a conventional method using a submicron particle size distribution measuring device.
  • a submicron particle size distribution measuring device for example, “COULTER N4 type” (trade name, manufactured by Beckman Coulter, Inc.) can be used.
  • the water-dispersible acrylic resin particles are preferably neutralized with a basic compound.
  • a neutralizing agent for water-dispersible acrylic resin particles ammonia or a water-soluble amino compound such as monoethanolamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, triethanol Amine, butylamine, dibutylamine, 2-ethylhexylamine, ethylenediamine, propylenediamine, methylethanolamine, dimethylethanolamine, diethylethanolamine, 2-amino-2-methylpropanol, diethanolamine, morpholine, etc. can be suitably used. .
  • Curing agent (B) examples of the curing agent (B) of the aqueous coating composition of the present invention include melamine resin (b-1), polyisocyanate compound (b-2), blocked polyisocyanate compound (b-3), and carbodiimide group-containing compound. (B-4) or the like can be used.
  • melamine resin (b-1) can be preferably used.
  • the curing agent (B) is used in a proportion of 1 to 50% by mass, preferably 3 to 30% by mass, more preferably 5 to 20% by mass, based on 100 parts by mass of the resin solid content in the aqueous coating composition. It is preferable to do.
  • the acrylic resin (A) contains a hydroxyl group.
  • the hydroxyl value of the acrylic resin (A) is 1 to 200 mgKOH / g, preferably 3 It is suitable to be in the range of ⁇ 100 mg KOH / g, more preferably 5 to 80 mg KOH / g.
  • Examples of the melamine resin (b-1) include methylol melamine such as dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine; alkyl etherified product of methylol melamine and alcohol; condensation of methylol melamine; An etherified product of alcohol with the product.
  • examples of the alcohol include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol and the like.
  • a commercially available product can be used as the melamine resin.
  • Examples of commercially available product names include “Cymel 303”, “Cymel 323”, “Cymel 325”, “Cymel 327”, “Cymel 350”, “Cymel 370”, “Cymel 380”, “Cymel 385”, “Cymel 212”, “Cymel 253”, “Cymel 254” (manufactured by Nihon Cytec Industries, Inc.); “RESIMIN 735”, “RESIMIN 740”, “RESIMIN 741”, “RESIMIN 745”, “RESIMIN 746”, “ “Resimin 747”, “(above, manufactured by Monsanto);“ Sumimar M55 ”,“ Sumimar M30W ”,“ Sumimar M50W ”(above, manufactured by Sumitomo Chemical);“ Uban 20SE ”,“ Uban 28SE ”(Mitsui Chemicals) And the like.
  • Melamine resin includes methyl ether melamine resin, butyl ether melamine resin, methyl-butyl mixed etherification in which methylol group of partially or fully methylol melamine resin is partially or completely etherified with methyl alcohol and / or butyl alcohol. Melamine resins can be used.
  • methyl etherified melamine resins can be suitably used from the viewpoint of solvent swelling resistance
  • imino group-containing methyl etherified melamine resins can be suitably used from the viewpoint of chipping resistance.
  • the curing catalyst is a sulfonic acid such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid; a neutralized salt of the sulfonic acid and an amine; A neutralized salt of a compound and an amine can be used.
  • a sulfonic acid such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid
  • a neutralized salt of the sulfonic acid and an amine A neutralized salt of a compound and an amine can be used.
  • the acrylic resin (A) generally contains a hydroxyl group, and in particular, the acrylic resin (A) has a hydroxyl value of 100 to 200 mgKOH. / G, preferably 130 to 180 mgKOH / g, more preferably 140 to 170 mgKOH / g.
  • the equivalent ratio (NCO / OH) of the isocyanate group of the isocyanate group-containing compound (b-2) to the hydroxyl group of the acrylic resin (A) is 0.5 to 2.0, preferably 0.8 to 1. It is preferable to be within the range of 5.
  • the polyisocyanate compound (b-2) is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, and aromatic polyisocyanates. And derivatives of the polyisocyanate.
  • aliphatic polyisocyanate examples include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3.
  • -Aliphatic diisocyanates such as butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, eg lysine ester triisocyanate, 1,4,8 -Triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, , And aliphatic triisocyanate such as 5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyl octane.
  • alicyclic polyisocyanate examples include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name) : Isophorone diisocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane (common name: hydrogenated xylylene diisocyanate) or The mixture, alicyclic diisocyanate such as norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2- (3-isocyanate Natopropyl) -2,5-di
  • araliphatic polyisocyanate examples include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ⁇ , ⁇ ′-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis.
  • Aroaliphatic diisocyanates such as (1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof, for example, araliphatic tris such as 1,3,5-triisocyanatomethylbenzene An isocyanate etc. can be mentioned.
  • aromatic polyisocyanate examples include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4′- or 4,4′-diphenylmethane diisocyanate or its Mixtures, 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, aromatic diisocyanates such as 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate, for example, triphenylmethane-4,4 ′, Aromatic triisocyanates such as 4 ′′ -triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, such as 4,4′-diphenylmethane-2,2 ′, 5 5'-tetra And aromatic tetraisocyanates such as isocyanate.
  • polyisocyanate derivatives examples include dimer, trimer, biuret, allophanate, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI) of the above polyisocyanate compounds. ) And crude TDI.
  • polyisocyanates and their derivatives may be used alone or in combination of two or more.
  • aliphatic diisocyanates, alicyclic diisocyanates, and derivatives thereof can be used alone or in combination of two or more.
  • a hydrophilized polyisocyanate compound (b-2 ′) obtained by modifying the polyisocyanate compound to be hydrophilic is particularly preferable from the viewpoint of smoothness of the resulting coating film. Is preferred.
  • hydrophilized polyisocyanate compound (b-2 ′) examples include an anionic hydrophilized polysiloxane obtained by reacting an active hydrogen group of an active hydrogen group-containing compound having an anionic group with an isocyanate group of a polyisocyanate compound.
  • Nonionic hydrophilized polyisocyanate compound (b-2'-2) obtained by reacting an isocyanate compound (b-2'-1) and a hydrophilic polyether alcohol such as polyoxyethylene monoalcohol and a polyisocyanate compound Etc.
  • the active hydrogen group-containing compound having an anionic group has an anionic group such as a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a betaine structure-containing group such as sulfobetaine, and can react with an isocyanate group.
  • an anionic group such as a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a betaine structure-containing group such as sulfobetaine
  • it is a compound having an active hydrogen group such as a hydroxyl group or an amino group, and hydrophilicity can be imparted to the polyisocyanate compound by reacting the compound with the polyisocyanate compound.
  • the active hydrogen group-containing compound having an anionic group is not particularly limited, and examples thereof include a compound having one anionic group and having two or more active hydrogen groups. More specifically, examples of the active hydrogen group-containing compound having a carboxyl group include 2,2-dimethylolacetic acid, 2,2-dimethylollactic acid, 2,2-dimethylolpropionic acid, and 2,2-dimethylolbutanoic acid.
  • Dihydroxylcarboxylic acids such as dimethylolheptanoic acid, dimethylolnonanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, such as 1-carboxy-1,5-pentylenediamine, dihydroxybenzoic acid, Examples thereof include diaminocarboxylic acids such as 3,5-diaminobenzoic acid, lysine and arginine, and half ester compounds of polyoxypropylene triol with maleic anhydride, phthalic anhydride and the like.
  • Examples of the active hydrogen group-containing compound having a sulfonic acid group include N, N-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid, 1,3-phenylenediamine-4,6-disulfonic acid, and diamino. Butanesulfonic acid, 3,6-diamino-2-toluenesulfonic acid, 2,4-diamino-5-toluenesulfonic acid, 2- (cyclohexylamino) -ethanesulfonic acid, 3- (cyclohexylamino) -propanesulfonic acid, etc. Is mentioned.
  • examples of the active hydrogen group-containing compound having a phosphate group include 2,3-dihydroxypropylphenyl phosphate.
  • Examples of the active hydrogen group-containing compound having a betaine structure-containing group include a sulfobetaine group-containing compound obtained by reaction of a tertiary amine such as N-methyldiethanolamine with 1,3-propane sultone. .
  • active hydrogen group-containing compounds having an anionic group may be modified to an alkylene oxide by adding an alkylene oxide such as ethylene oxide or propylene oxide.
  • active hydrogen group-containing compounds having an anionic group can be used alone or in combination of two or more.
  • a nonionic emulsifier and an anionic emulsifier can be used as the emulsifier used to impart water dispersibility to the polyisocyanate compound.
  • Polyethylene oxide can be preferably used as the nonionic group, and salts such as sulfonic acid and phosphoric acid are preferably used as the anionic group, and these may be used in combination.
  • polyisocyanate compound the same polyisocyanate compounds as described above can be used.
  • preferred examples include hexamethylene diisocyanate (HMDI), derivatives of hexamethylene diisocyanate, isophorone diisocyanate (IPDI), and isophorone diisocyanate. And derivatives thereof.
  • the blocked polyisocyanate compound (b-3) As the blocked polyisocyanate compound (b-3), the above-mentioned aliphatic polyisocyanate, alicyclic polyisocyanate, araliphatic polyisocyanate, aromatic polyisocyanate and derivatives thereof blocked with a blocking agent are used. .
  • derivatives include isocyanurate bodies, burette bodies, adduct bodies (for example, TMP (trimethylolpropane) adducts) and the like.
  • the blocking agent blocks free isocyanate groups.
  • the blocked polyisocyanate compound is heated to, for example, 100 ° C. or higher, preferably 130 ° C. or higher, the isocyanate group is regenerated and can easily react with the hydroxyl group.
  • blocking agents include phenolic compounds such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; ⁇ -caprolactam, ⁇ -valerolactam Lactam compounds such as ⁇ -butyrolactam, ⁇ -propiolactam; aliphatic alcohol compounds such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoe Ether compounds such as ether, propylene glycol monomethyl ether, methoxymethanol; benzyl alcohol; glycolic acid; glycolic acid esters such as methyl glycolate, ethyl glycolate,
  • Lactic acid ester Lactic acid ester; Alcohol compounds such as methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane Oxime compounds such as oximes; dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate Active methylene compounds such as acetylacetone; mercaptan compounds such as butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol; ace
  • a hydroxycarboxylic acid having a hydroxycarboxylic acid having one or more hydroxyl groups and one or more carboxyl groups in one molecule can be used as a part of the blocking agent.
  • the hydroxycarboxylic acid include hydroxypivalic acid and dimethylolpropionic acid.
  • the monoblock isocyanate compound blocked with hydroxycarboxylic acid has a carboxyl group derived from hydroxycarboxylic acid, and is preferable from the viewpoint of good water dispersibility based on the hydrophilicity of the carboxyl group.
  • an organic tin compound can be used as a curing catalyst.
  • the carbodiimide group-containing compound (b-4) can be obtained, for example, by reacting the isocyanate groups of the polyisocyanate compound with each other, and examples of the commercially available products include “Carbodilite V-02”, “Carbodilite V-02-L2”, “Carbodilite V-04”, “Carbodilite E-01”, “Carbodilite E-02” (all manufactured by Nisshinbo Co., Ltd.) and the like can be used.
  • the acrylic resin (A) generally contains a carboxyl group, and in particular, an acid derived from the carboxyl group of the acrylic resin (A).
  • the value is preferably in the range of 5 to 80 mgKOH / g, preferably 10 to 70 mgKOH / g, more preferably 30 to 70 mgKOH / g.
  • Urethane resin emulsion (C) The urethane resin emulsion (C) contained in the aqueous coating composition of the present invention is produced by reacting the polyisocyanate component (c1) and the polyol component (c2), and the polyisocyanate component (c1). ) Contains an alicyclic diisocyanate, the polyol component (c2) contains a polycarbonate diol, and the content of the polycarbonate diol is 50% by mass or more based on the total amount of the polyol component (c2). Is.
  • polyisocyanate (c1) component examples include essential alicyclic diisocyanates and other polyisocyanates.
  • alicyclic diisocyanate examples include isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, trans-1,4-cyclohexyl diisocyanate, and norbornene diisocyanate.
  • isophorone diisocyanate and dicyclohexylmethane-4,4′-diisocyanate are particularly preferable from the viewpoint of improving the organic solvent swelling resistance of the resulting coating film.
  • the content (mass%) of the alicyclic diisocyanate in the polyisocyanate component (c1) is preferably 50 to 100%, more preferably 70 to 100% from the viewpoint of chipping resistance.
  • polyisocyanates include diisocyanates other than alicyclic diisocyanates and polyisocyanates having 3 or more isocyanate groups in one molecule.
  • Diisocyanates other than alicyclic diisocyanates include tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, 3,3′-dimethyldiphenyl-4, Aromatic diisocyanates such as 4'-diisocyanate, dianisidine diisocyanate, tetramethylxylylene diisocyanate; 1,6-hexamethylene diisocyanate, 2,2,4 and / or (2,4,4) -trimethylhexamethylene diisocyanate, lysine Aliphatic diisocyanates such as diisocyanates are mentioned.
  • the above diisocyanate may be used in the form of a blocked isocyanate blocked with various blocking agents.
  • polyisocyanates having three or more isocyanate groups in one molecule include, for example, isocyanurate trimers, burette trimers, trimethylolpropane adducts of the above-mentioned diisocyanates; triphenylmethane triisocyanate, 1- Examples thereof include trifunctional or higher functional isocyanates such as methylbenzole-2,4,6-triisocyanate and dimethyltriphenylmethanetetraisocyanate.
  • isocyanate compounds are in the form of modified products such as carbodiimide modification, isocyanurate modification, biuret modification and the like. It may be used in the form of a blocked isocyanate blocked with various blocking agents.
  • polystyrene resin emulsion (C) examples include polycarbonate polyols including polycarbonate diol as an essential component, polyols having ester bonds, polycaprolactone polyols, low molecular polyols, polyether polyols, polybutadiene polyols, A silicone polyol etc. are mentioned.
  • Polycarbonate polyol is a compound obtained by a polycondensation reaction of a known polyol and a carbonylating agent by a conventional method.
  • Examples of the polyol used as a raw material for the polycarbonate polyol include diols and trihydric or higher alcohols.
  • diols include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, Linear aliphatic diols such as 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, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1, 8-octanediol, 2,2,4-trimethyl-1,3-pentane
  • aliphatic diols such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol; p-xylenediol, p-tetrachloroxylenediol, etc.
  • examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, a trimethylolpropane dimer, and pentaerythritol. These trivalent or higher alcohols can be used alone or in combination of two or more.
  • a known carbonylating agent can be used as a carbonylating agent used as a raw material for polycarbonate polyol.
  • alkylene carbonate, dialkyl carbonate, diaryl carbonate, phosgene and the like can be mentioned, and one of these can be used or two or more can be used in combination.
  • preferred are ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate and the like.
  • the polycarbonate diol used as an essential raw material in the present invention can be synthesized by using only a diol as a polyol to be reacted with the carbonylating agent without using a polyhydric alcohol such as a trihydric or higher alcohol. .
  • a diol component of the polycarbonate diol a diol having usually 6 or more carbon atoms, preferably 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, and further preferably 6 to 12 carbon atoms can be used.
  • diol having 6 or more carbon atoms examples include an alicyclic diol having a cycloalkylene group having 6 or more carbon atoms and an aliphatic diol having an alkylene group having 6 or more carbon atoms.
  • Examples of the alicyclic diol having a cycloalkylene group having 6 or more carbon atoms include 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, etc.
  • Preferred examples include alicyclic diols having 6 to 12 carbon atoms.
  • 1,4-cyclohexanedimethanol is preferred from the viewpoint of chipping resistance.
  • Examples of the aliphatic diol having an alkylene group having 6 or more carbon atoms include 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.
  • Linear aliphatic diols such as 3-methyl-1,5-pentanediol, 2-ethyl-1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2 -Branched chains such as ethyl-1,3- propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol Examples thereof include linear or branched aliphatic diols having 6 or more carbon atoms, preferably 6 to 10 carbon atoms, such as linear aliphatic diols.
  • linear aliphatic diols and branched aliphatic diols may be used, or both may be used in combination.
  • linear aliphatic diols are preferred from the viewpoint of chipping resistance, and 1,6-hexanediol is particularly preferred.
  • the diol component of the polycarbonate diol is preferably 90% by mass or more, particularly preferably 95% by mass or more, based on the total amount of the diol component.
  • the alicyclic diol having 6 or more carbon atoms having a cycloalkylene group is 50% by mass or more, particularly 65 to 100% by mass, more particularly 75 to 100% by mass, based on the total amount of diols having 6 or more carbon atoms. % Range is preferred.
  • the polycarbonate diol used as a raw material for the urethane resin emulsion (C) is a polycarbonate diol obtained from a diol component containing an alicyclic diol having a cycloalkylene group having 6 or more carbon atoms, that is, And polycarbonate diols obtained by reacting a diol component containing an alicyclic diol having a cycloalkylene group having 6 or more carbon atoms with a carbonylating agent.
  • the polycarbonate diol as the raw material of the urethane resin emulsion (C) includes an alicyclic diol having a cycloalkylene group having 6 or more carbon atoms and an alkylene group having 6 or more carbon atoms as a diol component.
  • the polycarbonate diol obtained by making the diol component and carbonylating agent to contain react can be mentioned.
  • 1,4-cyclohexanedimethanol is used as the alicyclic diol having a cycloalkylene group having 6 or more carbon atoms, and 1,6 as the aliphatic diol having an alkylene group having 6 or more carbon atoms.
  • -Hexanediol can be used.
  • the ratio of the mass of the alicyclic diol having a cycloalkylene group having 6 or more carbon atoms / the mass of the aliphatic diol having an alkylene group having 6 or more carbon atoms is preferably 20/80 to 80/20. Range.
  • the polycarbonate diol used as a raw material for the urethane resin emulsion (C) includes, as a diol component, the aliphatic diol having an alkylene group having 6 or more carbon atoms and the above 6 or more carbon atoms.
  • the polycarbonate diol component obtained from the diol component which contains the alicyclic diol which has a cycloalkylene group, and contains both 50 mass% or more in total with respect to the total amount of a diol component is mentioned.
  • 1,6-hexanediol is used as the aliphatic diol having an alkylene group having 6 or more carbon atoms
  • 1,4-cyclohexane is used as the alicyclic diol having a cycloalkylene group having 6 or more carbon atoms.
  • Dimethanol can be used.
  • the ratio of the mass of the aliphatic diol having an alkylene group having 6 or more carbon atoms / the mass of the alicyclic diol having a cycloalkylene group having 6 or more carbon atoms is preferably 20/80 to 80 / It can be in the range of 20.
  • examples of the polyol having an ester bond include polyester polyol and polyester polycarbonate polyol.
  • polyester polyol As the above-mentioned polyester polyol, a direct esterification reaction between a polyhydric alcohol and a polycarboxylic acid having an amount less than the stoichiometric amount of the polyhydric alcohol or an ester-forming compound such as an ester, an anhydride or a halide thereof; And / or those obtained by transesterification.
  • polyhydric alcohol used as a raw material for the polyester polyol examples include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 2-butyl-2-ethyl- 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5 -Pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1 , 8-octanediol, 2-methyl-1,8-octanedi
  • Examples of the polyvalent carboxylic acid or ester-forming compound used as a raw material for the polyester polyol include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedi Acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, 3,7-dimethyldecanedioic acid Aliphatic dicarboxylic acid compounds such as hydrogenated dimer acid and dimer acid; aromatic dicarboxylic acid compounds such as phthalic acid, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3 -Cyclopentanedicarboxylic
  • Polycarboxylic acids such as tricarboxylic acid-based compounds, acid anhydrides of these polycarboxylic acids, chlorides of the polycarboxylic acids, halides such as bromides, methyl esters, ethyl esters, propyl esters of the polycarboxylic acids Lower esters such as isopropyl ester, butyl ester, isobutyl ester, amyl ester; ⁇ -caprolactone, ⁇ -caprolactone, ⁇ -caprolactone, dimethyl- ⁇ -caprolactone, ⁇ -valerolactone, ⁇ -valerolactone, ⁇ -butyrolactone, etc. Lactone compounds It is.
  • examples of the polycaprolactone polyol include ring-opening polymerization products of caprolactone such as polycaprolactone diol.
  • examples of the low molecular weight polyol include polyhydric alcohols exemplified for polyester polyol. *
  • examples of the polyether polyol include ethylene oxide and / or propylene oxide adducts of the above low molecular polyols, polytetramethylene glycol, and the like.
  • polybutadiene polyols widely known in the technical field can be used as the polybutadiene polyol.
  • silicone polyol examples include a silicone oil compound having a hydroxyl group at the terminal having a siloxane bond in the molecule.
  • a carboxyl group-containing diol can be used as the polyol component (c2).
  • the carboxyl group-containing diol is used for introducing a hydrophilic group into the polyurethane molecule.
  • the hydrophilic group is a carboxyl group. Specific examples include dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolbutyric acid, and dimethylolvaleric acid.
  • the polycarbonate diol component of the urethane resin emulsion (C) is 50% by mass or more, particularly 75 to 100% by mass, more particularly 75% by mass, based on the total amount of the polyol component (c2), from the viewpoint of coating surface smoothness. , Preferably in the range of 90 to 100% by weight.
  • the urethane resin emulsion (C) blended in the composition of the present invention includes those using an amine component as necessary in addition to the polyisocyanate component (c1) and the polyol component (c2) during the production thereof. It is.
  • the amine component include monoamine compounds and diamine compounds.
  • the monoamine compound is not particularly limited, and a known general monoamine compound may be used alone or in combination of two or more.
  • the monoamine compounds include alkylamines such as ethylamine, propylamine, 2-propylamine, butylamine, 2-butylamine, tert-butylamine, and isobutylamine; aromatic amines such as aniline, methylaniline, phenylnaphthylamine, and naphthylamine; cyclohexylamine , Cycloaliphatic amines such as methylcyclohexylamine; ether amines such as 2-methoxyethylamine, 3methoxypropylamine, 2- (2-methoxyethoxy) ethylamine; ethanolamine, propanolamine, butylethanolamine, 1-amino-2 -Methyl-2-propanol, 2-amino-2-methylpropanol, diethanolamine, diisopropanol
  • the diamine compound is not particularly limited, and a known general diamine compound can be used alone or in combination of two or more.
  • the diamine compound include low molecular diamine compounds in which the alcoholic hydroxyl group of the above exemplified low molecular diols such as ethylene diamine and propylene diamine is substituted with amino groups; polyethers such as polyoxypropylene diamine and polyoxyethylene diamine Diamine compounds; mensendiamine, isophoronediamine, norbornenediamine, bis (4-amino-3-methyldicyclohexyl) methane, diaminodicyclohexylmethane, bis (aminomethyl) cyclohexane, 3,9-bis (3-aminopropyl) 2 , 4,8,10-tetraoxaspiro (5,5) undecane, etc .; m-xylenediamine, ⁇ - (m / paminophenyl) ethylamine, m-phen
  • carboxyl group neutralizing agent component can be used as necessary.
  • the carboxyl group neutralizing agent component is a basic compound that reacts with the carboxyl group of the carboxyl group-containing diol to form a hydrophilic salt.
  • trialkylamine compounds such as trimethylamine, triethylamine, tributylamine, N, N-dimethylethanolamine, N, N-dimethylpropanolamine, N, N-dipropylethanolamine, 1-dimethylamino-2-methyl- Tertiary amine compounds such as N, N-dialkylalkanolamine compounds such as 2-propanol, N-alkyl-N, N-dialkanolamine compounds, trialkanolamine compounds such as triethanolamine, ammonia, trimethylammonium Examples thereof include hydroxide, sodium hydroxide, potassium hydroxide, and lithium hydroxide. Among them, a tertiary amine compound is preferable because the obtained urethane resin emulsion (C) has good dispersion stability.
  • an internal branching agent and an internal cross-linking agent that give the polyurethane molecule a branching and / or cross-linking structure may be used.
  • these internal branching agents and internal crosslinking agents trivalent or higher polyols can be suitably used, and examples thereof include trimethylolpropane.
  • the production method of the urethane resin emulsion (C) is not particularly limited, and a known general method can be applied.
  • a production method a method of synthesizing a prepolymer or a polymer in a solvent inert to the reaction and having a large affinity for water, and then feeding this into water to disperse it is preferable.
  • an amine component used as necessary in water (a) a polyisocyanate component, a polyol component, and a necessity
  • a polymer is synthesized from the amine component used in accordance with this, and this is fed and dispersed in water.
  • the neutralizing agent component used as needed may be added beforehand to the water to feed, and may be added after feed.
  • Examples of the solvent that is inert to the reaction and has a high affinity for water used in the above preferred production method include acetone, methyl ethyl ketone, dioxane, tetrahydrofuran, N-methyl-2-pyrrolidone, and the like. . These solvents are usually used in an amount of 3 to 100% by mass based on the total amount of the above raw materials used for producing the prepolymer.
  • the mixing ratio is not particularly limited.
  • the blending ratio can be replaced with the molar ratio of the isocyanate group in the polyisocyanate component at the stage of reaction to the isocyanate reactive group in the polyol component and the amine component.
  • the molar ratio if there is a shortage of unreacted isocyanate groups in the dispersed polyurethane molecules, the coating film adhesion and / or coating strength may decrease when used as a coating, and if it is present excessively, Since the reactive isocyanate group may affect the dispersion stability and / or physical properties of the paint, the isocyanate reactive group is preferably 0.5 to 2.0 with respect to the isocyanate group 1.
  • the molar ratio of the isocyanate reactive group in the polyol component is preferably 0.3 to 1.0, more preferably 0.5 to 0.9, relative to the isocyanate group 1 in the polyisocyanate component. Further, the molar ratio of the isocyanate-reactive group in the amine component used as necessary is preferably 0.1 to 1.0, preferably 0.2 to 0.00, with respect to the isocyanate group 1 in the polyisocyanate component. 5 is more preferable.
  • the neutralization rate by the carboxyl group neutralizing agent component used as necessary is set within a range that gives sufficient dispersion stability to the obtained urethane resin emulsion (C). 0.5 to 2.0 times equivalent is preferable with respect to 1 mole number of carboxyl groups in the carboxyl group-containing diol, and 0.7 to 1.5 times equivalent is more preferable.
  • one or more emulsifiers such as a surfactant may be used.
  • the particle diameter is not particularly limited, but is preferably 1 ⁇ m or less and more preferably 500 nm or less because a good dispersion state can be maintained.
  • emulsifier well-known general anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, polymer surfactants, reactive surfactants used in urethane resin emulsions An agent or the like can be used.
  • an anionic surfactant, a nonionic surfactant, or a cationic surfactant is preferable because the cost is low and good emulsification is obtained.
  • anionic surfactant examples include alkyl sulfate compounds such as sodium dodecyl sulfate and ammonium dodecyl sulfate such as potassium dodecyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulforicinolate; alkali metal salt of sulfonated paraffin, Alkyl sulfonates such as ammonium salts of sulfonated paraffins; Fatty acid salts such as sodium laurate, triethanolamine oleate and tolethanolamine abiates; Alkyl aryl sulfonates such as sodium benzene sulfonate and alkali metal sulfates of alkali phenol hydroxyethylene; High alkyl Naphthalenesulfonate; naphthalenesulfonic acid formalin condensate; dialkyl Ruhokohaku salt; polyoxyethylene alkyl sulfate salt
  • nonionic surfactant examples include ethylene oxide and / or propylene oxide adduct of alcohol having 1 to 18 carbon atoms, ethylene oxide and / or propylene oxide adduct of alkylphenol, alkylene glycol and / or ethylenediamine ethylene oxide. And / or a propylene oxide adduct and the like.
  • Examples of the alcohol having 1 to 18 carbon atoms constituting the nonionic surfactant include methanol, ethanol, propanol, 2-propanol, butanol, 2-butanol, tertiary butanol, amyl alcohol, isoamyl alcohol, and tertiary amyl alcohol.
  • Hexanol, octanol, decane alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, etc., and alkylphenols include phenol, methylphenol, 2,4-ditertiarybutylphenol, 2,5-ditertiary alcohol.
  • alkylene glycol examples 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 and the like.
  • alkylene diamines examples include those of these alkylene glycols.
  • An alcoholic hydroxyl group is substituted with an amino group.
  • the ethylene oxide and propylene oxide adducts may be random adducts or block adducts.
  • cationic surfactant examples include quaternary ammonium salts such as primary to tertiary amine salts, pyridinium salts, alkylpyridinium salts, and halogenated alkyl quaternary ammonium salts.
  • the amount used when these emulsifiers are used is not particularly limited, and any amount can be used. However, when the weight ratio to the urethane resin 1 is less than 0.05, sufficient dispersibility cannot be obtained. If it exceeds 0.3, the physical properties such as the water resistance, strength, and elongation of the coating film obtained from the aqueous coating composition may be lowered, so 0.01 to 0.3 is preferable, and 0.05 to 0.2 is more preferable.
  • the solid content is not particularly limited, and any value can be selected.
  • the solid content is preferably 10 to 50% by mass because of good dispersibility and paintability, and more preferably 20 to 40% by mass.
  • the weight average molecular weight of the urethane resin dispersed in the urethane resin emulsion (C) is 2,000 to 50,000, and preferably 3,000 to 40,000 from the viewpoint of the smoothness of the resulting coating film.
  • the hydroxyl value is not particularly limited, and any value can be selected.
  • the hydroxyl value is represented by the consumption (mg) of KOH per 1 g of resin, and is usually 0 to 100 mgKOH / g.
  • the water-based coating composition of the present invention has a water tolerance of 10 or more, preferably 20 or more, more preferably 50 or more, and a number average molecular weight of 200 to 200, from the viewpoint of improving the smoothness of the coated surface of the multilayer coating film. It may further contain 1500, preferably 300 to 1000, more preferably 400 to 1000 oligomer compounds (excluding the acrylic resin (A)).
  • polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and etherified products thereof.
  • a hydroxyl group-containing oligomer particularly polyoxypropylene glyceryl ether.
  • Examples of commercially available products include GP400, GP600, GP1000 (manufactured by Sanyo Kasei Co., Ltd.) and the like.
  • the water tolerance of the oligomer is a value obtained by the following measurement.
  • the water tolerance of the oligomer was measured by the following method.
  • a sample (oligomer) of 5.0 g is taken into a 200 ml beaker having a diameter of 5 cm and diluted with 50 ml of acetone.
  • the sample solution is set to 20 ° C.
  • a newspaper printed with No. 4 type is placed under the bottom of the beaker, and deionized water is added dropwise while stirring with a magnetic stirrer.
  • water tolerance is defined as the maximum dripping amount (ml) of deionized water that is the limit of the type 4 newspaper that can be seen through the top of the beaker.
  • Aqueous paint composition of the present invention is an aqueous paint containing the acrylic resin (A), the curing agent (B) and the urethane resin emulsion (C).
  • the water-based paint is a term contrasted with an organic solvent-type paint, and generally, a film-forming resin, a pigment, and the like are dispersed and / or dispersed in water or a medium containing water as a main component (aqueous medium). It means dissolved paint.
  • the water content in the aqueous coating composition is preferably about 10 to 90% by mass, more preferably about 20 to 80% by mass, and further preferably about 30 to 60% by mass.
  • the amount of acrylic resin (A), curing agent (B), and urethane resin emulsion (C) in the aqueous coating composition is based on the total amount of component (A), component (B), and component (C) as solid content.
  • the acrylic resin (A) is 20 to 70% by mass, preferably 30 to 65% by mass, more preferably 40 to 60% by mass
  • the curing agent (B) is 5 to 20% by mass, preferably 7.5 to 20% by mass. %, More preferably 10 to 20% by mass
  • the urethane resin emulsion (C) is in the range of 10 to 50% by mass, preferably 15 to 45% by mass, more preferably 20 to 40% by mass. .
  • the amount of the oligomer (D) is 1 to 3 as a solid content based on the total amount of the components (A), (B), (C) and (D). 20% by weight. It is preferably in the range of 3 to 17.5% by mass, more preferably 5 to 15% by mass.
  • the water-based coating composition of the present invention can contain a modifying resin such as a polyester resin, an alkyd resin, a silicon resin, a fluororesin, and an epoxy resin.
  • a modifying resin such as a polyester resin, an alkyd resin, a silicon resin, a fluororesin, and an epoxy resin.
  • the aqueous coating composition preferably further contains a pigment (E).
  • a pigment (E) examples include a color pigment (E1), an extender pigment (E2), and a glitter pigment (E3), and these can be used alone or in combination of two or more.
  • the amount of the pigment (E) is such that the acrylic resin (A), the crosslinking agent (B) and the urethane resin emulsion (C) in the aqueous coating composition
  • the total solid content of 100 parts by weight is generally 1 to 300 parts by weight, preferably 20 to 200 parts by weight, and more preferably 50 to 150 parts by weight.
  • the water-based paint composition contains the color pigment (E1) and / or the extender pigment (E2), and the total content of the color pigment (E1) and the extender pigment (E2) is the acrylic content in the water-based paint composition.
  • Examples of the color pigment (E1) include titanium oxide, zinc white, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, selenium pigments, Examples include perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, and titanium oxide and carbon black can be preferably used.
  • the blending amount of the color pigment (E1) is such that the acrylic resin (A), the crosslinking agent (B), and the urethane resin emulsion (C) in the water-based coating composition.
  • the acrylic resin (A), the crosslinking agent (B), and the urethane resin emulsion (C) in the water-based coating composition In the range of usually 1 to 300 parts by weight, preferably 3 to 200 parts by weight, more preferably 5 to 150 parts by weight.
  • Examples of the extender pigment (E2) include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, alumina white, and the like. Among these, barium sulfate and talc are preferably used. Can do.
  • the extender pigment (E2) contains barium sulfate having an average primary particle diameter of 1 ⁇ m or less, more preferably barium sulfate having an average primary particle diameter in the range of 0.01 to 0.8 ⁇ m.
  • a multi-layer coating film having excellent smoothness and having an excellent appearance with high flip-flop properties and little metallic unevenness when the water-based second colored coating (Y) described later is a coating containing a glitter pigment (E3). Is preferable.
  • the average primary particle diameter of barium sulfate in the present invention is a value obtained by observing barium sulfate with a scanning electron microscope and averaging the maximum diameters of 20 barium sulfates on a straight line drawn randomly on an electron micrograph. It is.
  • the amount of the extender pigment (E2) is such that the acrylic resin (A), the cross-linking agent (B), and the urethane resin emulsion (C) in the aqueous paint composition ) In the range of usually 1 to 300 parts by weight, preferably 5 to 200 parts by weight, and more preferably 10 to 150 parts by weight.
  • Examples of the bright pigment (E3) include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, aluminum oxide, mica, titanium oxide and / or iron oxide coated with iron oxide, and oxide. Examples thereof include mica coated with titanium and / or iron oxide, glass flakes, hologram pigments, and the like. These bright pigments (E3) can be used alone or in combination of two or more.
  • the aluminum pigment includes non-leafing aluminum and leafing aluminum, and any of them can be used.
  • the amount of the glitter pigment (E3) is such that the acrylic resin (A), the crosslinking agent (B), and the urethane resin emulsion in the water-based paint composition.
  • the total solid content of (C) it can be usually in the range of 1 to 50 parts by mass, preferably 2 to 30 parts by mass, more preferably 3 to 20 parts by mass.
  • the water-based coating composition further contains a hydrophobic solvent (F) from the viewpoint of improvement in sagging resistance and resistance to cracking.
  • F hydrophobic solvent
  • the hydrophobic solvent (F) is desirably 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.
  • the organic solvent include hydrocarbon solvents such as rubber volatile oil, mineral spirit, toluene, xylene, and solvent naphtha; 1-hexanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1-hexanol, Decanol, benzyl alcohol, ethylene glycol mono 2-ethylhexyl ether, propylene glycol mono n-butyl ether, dipropylene glycol mono n-butyl ether, tripropylene glycol mono n-butyl ether, propylene glycol mono 2-ethylhexyl ether, propylene glycol monophenyl ether, etc.
  • Alcohol solvents such as n-butyl acetate, isobutyl acetate, isoamyl acetate, methyl amyl acetate, ethylene glycol monobutyl ether Methyl isobutyl ketone, cyclohexanone, ethyl n- amyl ketone solvents such as diisobutyl ketone. These can be used alone or in combination of two or more.
  • an alcohol-based hydrophobic solvent is preferably used from the viewpoint of the smoothness of the resulting coating film.
  • alcohol-based hydrophobic solvents having 7 to 14 carbon atoms are preferable, such as 1-octanol, 2-octanol, 2-ethyl-1-hexanol, ethylene glycol mono-2-ethylhexyl ether, propylene glycol mono n-butyl ether, and dipropylene. More preferred is at least one alcohol-based hydrophobic solvent selected from the group consisting of glycol mono n-butyl ether.
  • the blending amount of the hydrophobic solvent (F) is the total solid of the acrylic resin (A), the crosslinking agent (B) and the urethane resin emulsion (C).
  • the amount is preferably 2 to 40 parts by weight, more preferably 5 to 35 parts by weight, and still more preferably 10 to 30 parts by weight based on 100 parts by weight.
  • the water-based coating composition may be a thickener, an ultraviolet absorber, a light stabilizer, a curing catalyst, an antifoaming agent, a plasticizer, an organic solvent other than the hydrophobic solvent (F), or a surface conditioner, if necessary.
  • paint additives such as anti-settling agents can be contained.
  • the thickener examples include inorganic thickeners such as silicate, metal silicate, montmorillonite, colloidal alumina; copolymer of (meth) acrylic acid and (meth) acrylic ester, poly Polyacrylic acid thickeners such as sodium acrylate; one molecule has a hydrophilic part and a hydrophobic part, and in an aqueous medium, the hydrophobic part adsorbs to the surface of pigment or emulsion particles in the paint.
  • inorganic thickeners such as silicate, metal silicate, montmorillonite, colloidal alumina
  • copolymer of (meth) acrylic acid and (meth) acrylic ester poly Polyacrylic acid thickeners such as sodium acrylate
  • one molecule has a hydrophilic part and a hydrophobic part, and in an aqueous medium, the hydrophobic part adsorbs to the surface of pigment or emulsion particles in the paint.
  • an associative thickener that effectively exhibits a thickening action when the hydrophobic parts are associated with each other; cellulose thickeners such as carboxymethylcellulose, methylcellulose, and hydroxyethylcellulose; casein, sodium caseinate, and casein Protein thickeners such as ammonium acid; Alginate thickeners such as sodium alginate; Polyvinyl alcohol, Polyvinyl pyro Polyvinyl thickeners such as dong and polyvinylbenzyl ether copolymers; polyether thickeners such as pluronic polyethers, polyether dialkyl esters, polyether dialkyl ethers, polyether epoxy modified products; vinyl methyl ether-anhydrous maleic Examples thereof include maleic anhydride copolymer thickeners such as partial esters of acid copolymers; and polyamide thickeners such as polyamide amine salts. These thickeners can be used alone or in combination of two or more.
  • polyacrylic acid thickener Commercially available products can be used as the polyacrylic acid thickener.
  • Commercially available product names include, for example, “Primal ASE-60”, “Primal TT-615”, “Primal RM-5” manufactured by Rohm and Haas, “SN thickener 613”, “SN thickener 618” manufactured by San Nopco. ”,“ SN thickener 630 ”,“ SN thickener 634 ”,“ SN thickener 636 ”, and the like.
  • a commercial product can be used as the associative thickener.
  • Examples of commercially available product names include “UH-420”, “UH-450”, “UH-462”, “UH-472”, “UH-540”, “UH-752”, “ “UH-756VF”, “UH-814N”, “Primal RM-8W”, “Primal RM-825”, “Primal RM-2020NPR”, “Primal RM-12W”, “Primal RM-12W” manufactured by Rohm and Haas.
  • a polyacrylic acid-based thickener and / or an associative thickener more preferably an associative thickener, having a hydrophobic group at the terminal, and a molecular chain It is more preferable to use a urethane associative thickener containing a urethane bond therein.
  • a commercially available product can be used as the urethane associative thickener.
  • the blending amount of the thickener is 100 mass of the total solid content of the acrylic resin (A), the crosslinking agent (B) and the urethane resin emulsion (C).
  • the amount is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 3 parts by mass, and still more preferably 0.03 to 2 parts by mass with respect to parts.
  • the water-based coating composition comprises an acrylic resin (A), a crosslinking agent (B) and a urethane resin emulsion (C), and, if necessary, an oligomer (D), a pigment (E), a hydrophobic solvent (F) and other
  • the coating additive can be prepared by mixing and dispersing in an aqueous medium by a known method.
  • aqueous medium deionized water or a mixture of deionized water and a hydrophilic organic solvent can be used.
  • the hydrophilic organic solvent include propylene glycol monomethyl ether.
  • the solid content concentration of the water-based coating composition is usually preferably 30 to 70% by mass, more preferably 35 to 60% by mass, and still more preferably 40 to 55% by mass.
  • the water-based paint composition may be either a one-component paint or a multi-component paint, but contains an acrylic resin (A) and a urethane resin emulsion (C) as necessary from the viewpoint of storage stability. It can be set as the two-component paint which consists of a main ingredient and the hardening
  • the main agent further contains a pigment and a solvent
  • the curing agent further contains a curing catalyst and a solvent.
  • curing agent may contain surfactant further.
  • the proper viscosity varies depending on the paint composition.
  • the viscosity at 20 ° C. is usually about 20 to 60 seconds, preferably about 25 to 50 seconds.
  • the water-based coating composition can be applied onto the object by a method known per se, for example, air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, etc. May be performed. Of these, methods such as air spray coating and rotary atomization coating are preferred. Moreover, this coating method can be performed once to several times until a desired film thickness is obtained.
  • the coating amount of the water-based coating composition is preferably such that the cured film thickness is usually 5 to 40 ⁇ m, preferably 7 to 30 ⁇ m, more preferably 10 to 25 ⁇ m.
  • the coating film of the water-based coating composition itself can be cured by heating at 120 to 170 ° C., particularly 130 to 160 ° C. for about 10 to 40 minutes.
  • Heat curing can be performed using a known heating means, for example, a drying furnace such as a hot air furnace, an electric furnace, an infrared induction heating furnace or the like.
  • the coating film formed from the aqueous coating composition preferably has a water swelling ratio of 100% or less and an organic solvent swelling ratio of 300% or less after preliminary drying.
  • the water swelling rate is more preferably 60% or less, and still more preferably 20% or less.
  • the organic solvent swelling ratio is more preferably 250% or less, and still more preferably 200% or less.
  • a second colored coating film having good smoothness is obtained on the coating film having a low water swelling rate. Further, on the coating film having a low organic solvent swelling rate, the coating film by the organic solvent contained in the clear paint is used. A decrease in the smoothness of the coating surface due to swelling can also be prevented.
  • the water swelling rate and the water extraction rate are values measured as follows.
  • a 50 mm ⁇ 90 mm tin plate degreased with isopropanol is weighed, and its weight is defined as a.
  • Ford Cup No. On the surface of the tin plate, Ford Cup No.
  • the aqueous coating composition adjusted to a coating viscosity of 30 seconds as measured by 4 is applied by a rotary atomization method with an automatic coating machine so that the cured film thickness becomes 20 ⁇ m.
  • preheating is performed at 80 ° C. for 3 minutes, and the weight of the coated plate after preheating is weighed, and the weight is defined as b.
  • the coated plate is immersed in deionized water at 20 ° C.
  • the deionized water on the coated plate is wiped off with a waste cloth, the weight of the coated plate is weighed, and the weight is defined as c. Thereafter, the coated plate is dried at 110 ° C. for 1 hour, the weight of the coated plate after cooling is weighed, and the weight is defined as d.
  • organic solvent swelling ratio and the organic solvent extraction ratio refer to values measured as follows.
  • a 50 mm ⁇ 90 mm tin plate degreased with isopropanol is weighed, and its weight is defined as a.
  • Ford Cup No. On the surface of the tin plate, Ford Cup No.
  • the aqueous coating composition adjusted to a coating viscosity of 30 seconds as measured by 4 is applied by a rotary atomization method with an automatic coating machine so that the cured film thickness becomes 20 ⁇ m.
  • preheating is performed at 80 ° C. for 3 minutes, and the weight of the coated plate after preheating is weighed, and the weight is defined as b.
  • the coated plate is immersed in an organic solvent at 20 ° C. for 1 minute.
  • the painted surface of the aqueous coating composition is not wiped off, and the solvent remaining on the surface is sucked into the waste for 30 seconds while standing vertically on the waste.
  • the weight of the coated plate is weighed, and the weight is defined as c.
  • the coated plate is dried at 110 ° C. for 1 hour, the weight of the coated plate after cooling is weighed, and the weight is defined as d.
  • organic solvent a 70/30 (part by mass) mixed solvent of 3-ethoxyethyl propionate / butanol was used.
  • Organic solvent swelling ratio (%) [ ⁇ (ca) / (da) ⁇ -1] ⁇ 100 (3)
  • Organic solvent extraction rate (%) [1- ⁇ (da) / (ba) ⁇ ] ⁇ 100 (4)
  • the multi-layer coating film forming method of the present invention comprises the following steps (1) to (4), Step (1): A step of forming the first colored coating film by coating the aqueous first colored paint (X), Step (2): A step of forming a second colored coating film by applying an aqueous second colored coating material (Y) on the first colored coating film formed in the step (1). Step (3): a step of applying a clear paint (Z) on the second colored coating film formed in the step (2) to form a clear coating film, and a step (4): the step (1). A step of simultaneously baking and drying the first colored coating film, the second colored coating film and the clear coating film formed in (3), In which the aqueous first colored paint (X) is the aqueous paint composition of the present invention.
  • the aqueous coating composition of the present invention is applied as the aqueous first colored coating material (X) on the article to be coated.
  • the article to be coated to which the water-based first colored paint (X) is coated is not particularly limited.
  • the article to be coated include an outer plate part of an automobile body such as a passenger car, a truck, a motorcycle, and a bus; an automobile part such as a bumper; an outer plate part of a home electric product such as a mobile phone and an audio device. it can. Of these, the outer plate portion of the automobile body and the automobile parts are preferable.
  • the material of these objects to be coated is not particularly limited.
  • metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, galvanized steel, zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.) plated steel; polyethylene resin, polypropylene resin, acrylonitrile- Plastic materials such as butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, mixtures of these resins, various fiber reinforced plastics (FRP); glass And inorganic materials such as cement and concrete; wood; and fiber materials such as paper and cloth.
  • ABS butadiene-styrene
  • FRP fiber reinforced plastics
  • glass And inorganic materials such as cement and concrete; wood; and fiber materials such as paper and cloth.
  • metal materials and plastic materials are preferred.
  • the object to be coated may be a metal surface of the metal material or a vehicle body formed from the metal material, or a surface treatment such as phosphate treatment, chromate treatment, or complex oxide treatment.
  • a coating film may be formed thereon.
  • Examples of the coated material on which the coating film has been formed include those in which a surface treatment is applied to the substrate as necessary and an undercoat coating film is formed thereon.
  • a vehicle body in which an undercoat film is formed with an electrodeposition paint is preferable, and a vehicle body in which an undercoat film is formed with a cationic electrodeposition paint is particularly preferable.
  • the object to be coated may be one obtained by performing surface treatment, primer coating, or the like on the plastic material or a plastic surface such as an automobile part molded from the plastic material, if necessary. Further, a combination of the plastic material and the metal material may be used.
  • the first colored coating film is preferably subjected to preheating (preheating), air blowing, etc. under heating conditions in which the coating film does not substantially harden before applying the aqueous second colored paint (Y).
  • the cured coating film is a cured and dried state specified in JIS K 5600-1-1, that is, the center of the coating surface is strongly sandwiched between the thumb and index finger, and the coating surface has a dent due to fingerprints.
  • the coating film does not stick, the movement of the coating film is not felt, and the center of the coating surface is rapidly and repeatedly rubbed with a fingertip so that the coating surface is not rubbed.
  • the uncured coating film is a state in which the coating film has not reached the above-mentioned cured and dried state, and includes a dry-to-touch state and a semi-cured and dried state defined in JIS K 5600-1-1.
  • the preheating temperature is preferably 40 to 120 ° C, more preferably 60 to 100 ° C, and still more preferably 70 to 90 ° C.
  • the preheating time is preferably 30 seconds to 15 minutes, more preferably 1 to 12 minutes, and even more preferably 2 to 10 minutes.
  • the air blow can be usually performed by blowing air heated to a normal temperature or a temperature of 25 ° C. to 80 ° C. for 30 seconds to 15 minutes on the surface to be coated.
  • the first colored coating film Before applying the aqueous second colored paint (Y), the first colored coating film has a solid content of usually 60 to 100% by mass, particularly 80 to 80% by the above-mentioned means such as preheating and air blowing. It is preferable to adjust so as to be in the range of 100% by mass, more particularly 90 to 100% by mass.
  • the water-based second colored paint (Y) applied on the first colored coating film is generally intended to give an excellent appearance to the article to be coated, and includes, for example, a carboxyl group, a hydroxyl group and the like.
  • a resin component comprising a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin, and an epoxy resin having a crosslinkable functional group and a curing agent such as the crosslinking agent (B), together with a pigment and other additives.
  • a material which is dissolved or dispersed in water to form a paint can be used.
  • thermosetting water-based paint using a hydroxyl group-containing resin as a base resin and the melamine resin (b-1) as a crosslinking agent is preferable.
  • the color pigment (E1), extender pigment (E2), glitter pigment (E3), or the like can be used.
  • water-based 2nd coloring paint (Y) contains a color pigment (E1) and / or a luster pigment (E3) as at least 1 sort (s) of the said pigment.
  • Examples of the color pigment (E1) include titanium oxide, zinc white, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, and quinacridone pigment exemplified in the description of the aqueous coating composition. , Isoindoline pigments, selenium pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, and the like.
  • the blending amount of the colored pigment (E1) is based on 100 parts by mass of the resin solid content in the aqueous second colored paint (Y). Usually, it is suitable to be in the range of 1 to 150 parts by mass, preferably 3 to 130 parts by mass, more preferably 5 to 110 parts by mass.
  • Examples of the glitter pigment (E3) include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, aluminum oxide, mica, titanium oxide and / or iron oxide exemplified in the description of the aqueous coating composition. And mica, glass flakes and hologram pigments coated with aluminum oxide, titanium oxide and / or iron oxide. Among these, aluminum, aluminum oxide, mica, aluminum oxide coated with titanium oxide and / or iron oxide, mica coated with titanium oxide and / or iron oxide are preferably used, and aluminum is particularly preferably used.
  • the glitter pigment (E3) can be used alone or in combination of two or more.
  • the glitter pigment (E3) is preferably flake shaped. Further, as the glitter pigment (E3), those having a longitudinal dimension of 1 to 100 ⁇ m, particularly 5 to 40 ⁇ m, and a thickness of 0.001 to 5 ⁇ m, particularly 0.01 to 2 ⁇ m are suitable. .
  • the blending amount of the glitter pigment (E3) is 100 parts by mass of the resin solid content in the water-based second colored paint (Y).
  • the standard is usually 1 to 50 parts by mass, preferably 2 to 30 parts by mass, more preferably 3 to 20 parts by mass.
  • the aqueous second colored paint (Y) preferably contains the hydrophobic solvent (F).
  • the hydrophobic solvent (F) an alcohol-based hydrophobic solvent is preferably used from the viewpoint of excellent glitter of the resulting coating film.
  • alcoholic hydrophobic solvents having 7 to 14 carbon atoms such as 1-octanol, 2-octanol, 2-ethyl-1-hexanol, ethylene glycol mono-2-ethylhexyl ether, propylene glycol mono n-butyl ether, dipropylene More preferred is at least one alcohol-based hydrophobic solvent selected from the group consisting of glycol mono n-butyl ether.
  • the blending amount thereof is 2 to 70 masses based on 100 parts by mass of the resin solid content in the aqueous second colored paint (Y). Parts, preferably 11 to 60 parts by weight, more preferably 16 to 50 parts by weight.
  • the aqueous second colored paint (Y) may further include a curing catalyst, a thickener, an ultraviolet absorber, a light stabilizer, an antifoaming agent, a plasticizer, an organic solvent, a surface conditioner, and an anti-settling agent as necessary.
  • a curing catalyst such as can be contained. These paint additives can be used alone or in combination of two or more.
  • Water-based second colored paint (Y) can be applied by a method known per se, for example, air spray, airless spray, rotary atomizer, etc., and electrostatic application may be performed at the time of painting.
  • the coating film thickness can usually be in the range of 5 to 30 ⁇ m, preferably 8 to 25 ⁇ m, and more preferably 10 to 20 ⁇ m as a cured film thickness.
  • Step (3) In the multilayer coating film forming method of the present invention, the clear paint (Z) is applied on the paint film (second colored paint film) of the aqueous second colored paint (Y) formed in the step (2).
  • the second colored coating film is preferably subjected to the preheating, air blowing or the like under heating conditions in which the coating film is not substantially cured before the clear paint (Z) is applied.
  • the preheating temperature is preferably 40 to 100 ° C, more preferably 50 to 90 ° C, and still more preferably 60 to 80 ° C.
  • the preheating time is preferably 30 seconds to 15 minutes, more preferably 1 to 10 minutes, and even more preferably 2 to 5 minutes.
  • the air blow can be usually performed by blowing air heated to a normal temperature or a temperature of 25 ° C. to 80 ° C. for 30 seconds to 15 minutes on the surface to be coated.
  • the second colored coating film is usually subjected to the above preheating, air blowing, etc. before applying the clear paint (Z), so that the solid content of the coating film is usually 70 to 100% by mass, preferably It is preferable to adjust the amount to be in the range of 80 to 100% by mass, more preferably 90 to 100% by mass.
  • thermosetting clear paint composition for painting automobile bodies
  • thermosetting clear coating composition examples include an organic solvent type thermosetting coating composition containing a base resin having a crosslinkable functional group and a crosslinking agent, an aqueous thermosetting coating composition, and a powder thermosetting.
  • a coating composition etc. can be mentioned.
  • Examples of the crosslinkable functional group possessed by the base resin include a carboxyl group, a hydroxyl group, an epoxy group, and a silanol group.
  • Examples of the base resin include acrylic resin, polyester resin, alkyd resin, urethane resin, epoxy resin, and fluorine resin.
  • Examples of the crosslinking agent 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.
  • the base resin / crosslinking agent combination of the clear paint (Z) includes carboxyl group-containing resin / epoxy group-containing resin, hydroxyl group-containing resin / polyisocyanate compound, hydroxyl group-containing resin / blocked polyisocyanate compound, hydroxyl group-containing resin / melamine resin. Etc. are preferred.
  • the clear paint (Z) may be a one-component paint or a multi-component paint such as a two-component urethane resin paint.
  • the clear paint (Z) can contain a color pigment (E1), a glitter pigment (E3), a dye, etc. as long as it does not impair transparency, and further an extender pigment (E2). ),
  • An ultraviolet absorber, a light stabilizer, an antifoaming agent, a thickener, a rust preventive, a surface conditioner, and the like can be appropriately contained.
  • the clear paint (Z) can be applied to the coating surface of the water-based second colored paint (Y) by a method known per se, for example, airless spray, air spray, rotary atomizer, etc. At this time, electrostatic application may be performed.
  • the clear paint (Z) can usually be applied so that the cured film thickness is in the range of 20 to 80 ⁇ m, preferably 25 to 60 ⁇ m, more preferably 30 to 50 ⁇ m.
  • the clear paint (Z) after applying the clear paint (Z), if necessary, it can be preheated at room temperature for about 1 to 60 minutes or at about 50 to 110 ° C. for about 1 to 30 minutes.
  • Step (4) In the method for forming a multilayer coating film of the present invention, the uncured first colored coating film, the uncured second colored coating film and the uncured clear coating film formed in the above steps (1) to (3) At the same time, it is cured by heating.
  • the curing of the first colored coating film, the second colored coating film, and the clear coating film can be performed by a normal coating film baking means, for example, hot air heating, infrared heating, high-frequency heating, or the like.
  • the heating temperature is preferably 80 to 180 ° C, more preferably 110 to 170 ° C, and further preferably 130 to 160 ° C.
  • the heating time is preferably 10 to 90 minutes, more preferably 15 to 60 minutes.
  • Production and production example 1 of hydroxyl group-containing acrylic resin A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device was charged with 30 parts of propylene glycol monopropyl ether, heated to 85 ° C., and then 10 parts of styrene, methyl 30 parts of methacrylate, 15 parts of 2-ethylhexyl acrylate, 11.5 parts of n-butyl acrylate, 30 parts of hydroxyethyl acrylate, 3.5 parts of acrylic acid, 10 parts of propylene glycol monopropyl ether and 2,2′-azobis (2, A mixture of 2 parts of 4-dimethylvaleronitrile) was added dropwise over 4 hours and aged for 1 hour after completion of the addition.
  • Monomer emulsion (1) 42 parts of deionized water, 0.72 part of “AQUALON KH-10”, 2.1 parts of methylenebisacrylamide, 2.8 parts of styrene, 16.1 parts of methyl methacrylate, 28 parts of ethyl acrylate, 21 parts of n-butyl acrylate was mixed and stirred to obtain a monomer emulsion (1).
  • Monomer emulsion (2) 18 parts of deionized water, 0.31 part of “AQUALON KH-10”, 0.03 part of ammonium persulfate, 5.1 part of methacrylic acid, 5.1 part of 2-hydroxyethyl acrylate, 3 parts of styrene Part, 6 parts of methyl methacrylate, 1.8 parts of ethyl acrylate and 9 parts of n-butyl acrylate were mixed and stirred to obtain a monomer emulsion (2).
  • the obtained urethane resin emulsion (C-1) had a solid content of 30%, a weight average molecular weight of 29000, an acid value of 21 mgKOH / g, and an average particle size of 100 nm.
  • Urethane resin emulsions (C-11) to (C-14) are resins for comparative examples.
  • (* 1) UMC (1/1): the diol components are 1,6-hexanediol and 1,4-cyclohexanedimethanol, the mass of 1,6-hexanediol / the mass of 1,4-cyclohexanedimethanol 1/1 polycarbonate diol, manufactured by Ube Industries.
  • DMPA dimethylolpropionic acid
  • 1,4BD 1,4-butanediol
  • MHDI hexamethylene diisocyanate
  • IPDI isophorone diisocyanate
  • MDI dicyclohexyl Methane-4,4'-diisocyanate
  • Production Example 1 of water-based coating composition (X) 25.5 parts of the hydroxyl group-containing acrylic resin (A-1) solution obtained in Production Example 1 (resin solid content: 10.2 parts), rutile titanium dioxide (E1-1) (trade name “JR-806”, TAIKEA Co., Ltd. Company) 87 parts, carbon black (E1-2) (trade name “Carbon MA-100” manufactured by Mitsubishi Chemical Co., Ltd.) 0.8 part and deionized water 43 parts were mixed and mixed with 2- (dimethylamino) ethanol. After adjusting to pH 8.0, the mixture was dispersed for 30 minutes with a paint shaker to obtain a pigment dispersion paste.
  • ASE-60 alkali swelling type thickener, trade name, manufactured by Rohm and Haas
  • 2- (dimethylamino) ethanol and deionized water were added to the resulting mixture, pH 8.2, paint solids content 44% Ford Cup No. 20 ° C
  • An aqueous coating composition (X-1) having a viscosity of 30 according to 4 was obtained. Further, the obtained water-based coating composition (X-1) was applied so that the cured film thickness was 20 ⁇ m, and after heating at 80 ° C. for 3 minutes, the water swelling rate of the coating film was 20%, and the organic solvent ( The swelling ratio was 180% (70/30 (part by mass) mixed solvent of 3-ethoxyethylpropionate / butanol).
  • Examples 2 to 12 and Comparative Examples 1 to 4 By using the raw materials shown in Table 2 below as the acrylic resin, melamine resin, blocked polyisocyanate compound and urethane resin emulsion, and adjusting the composition shown in Table 2 in the same manner as in Example 1, pH 8.2, paint solids Min. 44%, Ford Cup no.
  • the aqueous coating compositions (X-2) to (X-16) having a viscosity of 30 according to 4 were obtained.
  • the blocked polyisocyanate compound (B-3) is Desmodur BL3475 (diethyl malonate block hexamethylene diisocyanate, manufactured by Bayer).
  • the oligomer (D-1) is polyoxypropylene glycerine ether (GP600 (trade name), molecular weight 600, manufactured by Sanyo Kasei Co., Ltd.) and has a water tolerance of 100 or more.
  • the formulation shown in Table 2 is a solid content formulation.
  • polyester resin solution having a solid content concentration of 70% was obtained.
  • the obtained polyester resin had an acid value of 46 mgKOH / g, a hydroxyl value of 150 mgKOH / g, and a weight average molecular weight of 6400.
  • Phosphate group-containing resin solution Mixing 27.5 parts of methoxypropanol and 27.5 parts of isobutanol in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device The solvent was added and heated to 110 ° C.
  • the acid value due to the phosphate group of the phosphate group-containing resin was 83 mgKOH / g, the hydroxyl value was 29 mgKOH / g, and the weight average molecular weight was 10,000.
  • Phosphoric acid group-containing polymerizable monomer put 57.5 parts monobutyl phosphoric acid and 41 parts isobutanol in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device, After raising the temperature to 90 ° C., 42.5 parts of glycidyl methacrylate was added dropwise over 2 hours. Then, after further aging with stirring for 1 hour, 59 parts of isopropanol was added to obtain a phosphate group-containing polymerizable monomer solution having a solid concentration of 50%. The acid value due to the phosphate group of the obtained monomer was 285 mgKOH / g.
  • Manufacture example 19 of water-based second colored paint (Y) 100 parts of the hydroxyl group-containing acrylic resin (A-2) dispersion obtained in Production Example 2 (solid content 30 parts), 57 parts of the polyester resin solution obtained in Production Example 17 (solid content 40 parts), obtained in Production Example 18 Brilliant pigment dispersion 62 parts (resin solid content 4 parts) and melamine resin (trade name “Cymel 325” manufactured by Nippon Cytec Industries, Ltd., solid content 80%) 37.5 parts (solid content 30 parts) uniformly Further, a polyacrylic acid thickener (trade name “Primal ASE-60” manufactured by Rohm and Haas), 2- (dimethylamino) ethanol and deionized water were added to adjust the pH to 8.0, and the solid content of the paint was 25. %, Ford Cup No. 20 at 20 ° C. An aqueous second colored paint (Y-1) having a viscosity of 40 and a viscosity of 40 seconds was obtained.
  • Test plates Aqueous paint compositions (X-1) to (X-16) obtained in Examples 1 to 12 and Comparative Examples 1 to 4, and an aqueous second colored paint (Y-1) obtained in Production Example 19 ), Test plates were produced as follows and evaluated.
  • Cathode electrodeposition paint (trade name “Electron GT-10” manufactured by Kansai Paint Co., Ltd.) is electrodeposited on the cold-rolled steel sheet that has been subjected to zinc phosphate conversion treatment to a cured film thickness of 20 ⁇ m. It was heated and cured to give a test article.
  • Example 13 Using the rotary atomizing electrostatic coater, the cured coating film thickness of 20 ⁇ m was obtained by applying the aqueous coating composition (X-1) obtained in Example 1 as the aqueous first colored coating to the test object. Electrostatic coating was performed, and after standing for 3 minutes, preheating was performed at 80 ° C. for 3 minutes. Next, the aqueous second colored paint (Y-1) obtained in Production Example 19 is applied onto the uncured first colored coating film using a rotary atomizing electrostatic coater so that the cured film thickness becomes 15 ⁇ m. The film was electrostatically coated, allowed to stand for 5 minutes, and then preheated at 80 ° C. for 3 minutes.
  • an acrylic resin solvent-type top clear coating (trade name “Magicron Kino-1210” manufactured by Kansai Paint Co., Ltd., hereinafter referred to as “clear coating (Z-1)” may be used.
  • heating at 140 ° C. for 30 minutes to cure the multilayer coating consisting of the first colored coating, the second colored coating and the clear coating The Ri test plate was produced.
  • Example 14 to 24 and Comparative Examples 5 to 8 In Example 13, except that the aqueous coating composition (X-1) obtained in Example 1 was changed to any of the aqueous coating compositions (X-2) to (X-16) shown in Table 2 above, Each test plate was produced in the same manner as in Example 13.

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Abstract

L'invention porte sur une composition de revêtement à base d'eau réalisant un excellent aspect de finition et ayant une excellente aptitude à être enlevée dans un nettoyage sous cloche ; et sur un procédé à 3 applications et 1 cuisson, dans lequel une première matière de revêtement colorée à base d'eau, une deuxième matière de revêtement colorée à base d'eau et une matière de revêtement transparente sont successivement appliquées sur un objet devant être revêtu et le film de revêtement à trois couches ainsi obtenu est chauffé et durci en même temps, le procédé permettant de former un film de revêtement multicouche ayant un excellent caractère lisse. La composition du revêtement à base d'eau est caractérisée en ce qu'elle comprend (A) une résine acrylique, (B) un durcisseur et (C) une émulsion d'une résine d'uréthane ayant une masse moléculaire moyenne en poids de 2 000 à 50 000 obtenue à partir d'ingrédients constitutifs comprenant un ingrédient polyisocyanate et un ingrédient polyol, l'ingrédient polyisocyanate comprenant un diisocyanate alicyclique et l'ingrédient polyol comprenant un polycarbonatediol, qui représente au moins 50 % en masse de la totalité de l'ingrédient polyol.
PCT/JP2010/051899 2009-02-18 2010-02-09 Composition de revêtement à base d'eau et procédé de formation d'un film de revêtement multicouche WO2010095541A1 (fr)

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CA 2751955 CA2751955C (fr) 2009-02-18 2010-02-09 Composition de revetement a base d'eau et procede de formation d'un film de revetement multicouche
CN201080008190.1A CN102317386B (zh) 2009-02-18 2010-02-09 水性涂料组合物及形成多层涂膜的方法
US13/201,953 US8993673B2 (en) 2009-02-18 2010-02-09 Water-based coating composition and method of forming multilayered coating film

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JP2009-172644 2009-07-24
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WO2012000735A1 (fr) * 2010-07-01 2012-01-05 Basf Coatings Gmbh Procédé de mise en peinture à plusieurs couches chromatiques et/ou à effet, la composition de la couche chromatique contenant une cétone pour diminuer le nombre de piqûres
WO2012000730A1 (fr) * 2010-07-01 2012-01-05 Basf Coatings Gmbh Procédé de mise en peinture à plusieurs couches chromatiques et/ou à effet, la composition de la couche chromatique contenant une cétone cycloaliphatique à substitution alkyle pour diminuer le nombre de piqûres
WO2014014028A1 (fr) * 2012-07-20 2014-01-23 Dic株式会社 Agent de revêtement et article produit l'utilisant
JPWO2013141305A1 (ja) * 2012-03-22 2015-08-03 日本ペイント株式会社 複層塗膜形成方法
JP7313592B1 (ja) * 2022-02-02 2023-07-24 関西ペイント株式会社 複層塗膜形成方法
JP7324386B1 (ja) * 2022-02-02 2023-08-09 関西ペイント株式会社 複層塗膜形成方法
WO2023149263A1 (fr) * 2022-02-02 2023-08-10 関西ペイント株式会社 Procédé de formation d'un film de revêtement multicouche
WO2023149262A1 (fr) * 2022-02-02 2023-08-10 関西ペイント株式会社 Procédé de formation de film de revêtement multicouche
WO2023149261A1 (fr) * 2022-02-02 2023-08-10 関西ペイント株式会社 Méthode de formation de film de revêtement multicouche

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WO2012000730A1 (fr) * 2010-07-01 2012-01-05 Basf Coatings Gmbh Procédé de mise en peinture à plusieurs couches chromatiques et/ou à effet, la composition de la couche chromatique contenant une cétone cycloaliphatique à substitution alkyle pour diminuer le nombre de piqûres
JPWO2013141305A1 (ja) * 2012-03-22 2015-08-03 日本ペイント株式会社 複層塗膜形成方法
WO2014014028A1 (fr) * 2012-07-20 2014-01-23 Dic株式会社 Agent de revêtement et article produit l'utilisant
JP7313592B1 (ja) * 2022-02-02 2023-07-24 関西ペイント株式会社 複層塗膜形成方法
JP7324386B1 (ja) * 2022-02-02 2023-08-09 関西ペイント株式会社 複層塗膜形成方法
WO2023149263A1 (fr) * 2022-02-02 2023-08-10 関西ペイント株式会社 Procédé de formation d'un film de revêtement multicouche
WO2023149262A1 (fr) * 2022-02-02 2023-08-10 関西ペイント株式会社 Procédé de formation de film de revêtement multicouche
WO2023149261A1 (fr) * 2022-02-02 2023-08-10 関西ペイント株式会社 Méthode de formation de film de revêtement multicouche
JP7352766B1 (ja) * 2022-02-02 2023-09-28 関西ペイント株式会社 複層塗膜形成方法

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