Classifications

• • 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
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/36—Successively applying liquids or other fluent materials, e.g. without intermediate treatment
• • 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
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
  • B05D5/06—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects
• • 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
  • B05D7/24—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 for applying particular liquids or other fluent materials
• • 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
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
• • 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
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes

Definitions

• the present invention relates to a method for forming a multilayer coating film.
• paint The purpose of applying paint is mainly to protect the material and add beauty.
• aesthetic appearance, especially ⁇ texture,'' is important in order to enhance their product appeal.
• Metallic luster is a mirror-like surface with no graininess, and when viewed perpendicularly to the painted plate (highlight), it shines, and when viewed from diagonally above the painted plate (shade). ) is a texture characterized by a dark appearance, that is, a large difference in brightness between the highlight area and the shade area.
• Patent Document 2 discloses that a metallic paint base containing a glittering material, a non-volatile solid content including a resin, and a solvent is diluted at a dilution rate of 150 to 500% using a diluent consisting of a high boiling point solvent and a low boiling point solvent. According to a metallic paint characterized by diluting and adding 5 to 10 parts by weight of a viscous resin to 100 parts by weight of the resin in the metallic paint base, a good metallic appearance can be achieved. is listed.
• coatings are required to not only give an aesthetic appearance but also protect the material, which requires excellent coating performance such as high adhesion.
• An object of the present invention is to provide a method for forming a multilayer coating film that can form a multilayer coating film that has excellent metallic luster and can exhibit high coating performance.
• the present invention includes the subject matter described in the following sections.
• Step (1) a step of coating a glittering paint composition (Y) containing indium particles (y1) on the object to be coated to form a glittering coating film;
• Step (2) A clear coating composition (Z) containing a hydroxyl group-containing acrylic resin (z1) and a polyisocyanate compound (z2) is applied onto the glitter coating film obtained in step (1) to form a clear coating.
• Step (3) of forming a film Curing the glitter coating formed in step (1) and the clear coating formed in step (2) by heating them separately or simultaneously.
• a method for forming a multilayer coating film comprising the steps of: A method for forming a multilayer coating film, wherein the hydroxyl value of the hydroxyl group-containing acrylic resin (z1) is within the range of 10 to 75 mgKOH/g.
• Section 2. The method for forming a multilayer coating according to Item 1, wherein the glitter coating composition (Y) further contains a hydroxyl group-containing resin (y2).
• Item 3 The method for forming a multilayer coating according to Item 1 or 2, wherein the glitter coating composition (Y) further contains a melamine resin (y3).
• the equivalent ratio (NCO/OH) of the total mol of isocyanate groups of the polyisocyanate compound (z2) to the total mol of hydroxyl groups of the hydroxyl group-containing acrylic resin (z1) is 0.7 to The method for forming a multilayer coating film according to any one of Items 1 to 3, which is within the range of 1.5.
• the method for forming a multilayer coating film of the present invention it is possible to form a multilayer coating film that has excellent metallic luster and exhibits excellent coating performance such as adhesion.
• the multilayer coating film forming method of the present invention includes the following steps (1) to (3): Step (1): a step of coating a glittering paint composition (Y) containing indium particles (y1) on the object to be coated to form a glittering coating film; Step (2): A clear coating composition (Z) containing a hydroxyl group-containing acrylic resin (z1) and a polyisocyanate compound (z2) is applied onto the glitter coating film obtained in step (1) to form a clear coating.
• Step (3) of forming a film Curing the glitter coating formed in step (1) and the clear coating formed in step (2) by heating them separately or simultaneously.
• a method for forming a multilayer coating film comprising the steps of: In this method, the hydroxyl value of the hydroxyl group-containing acrylic resin (z1) is within the range of 10 to 75 mgKOH/g.
• a glitter coating composition (Y) containing indium particles (y1) is applied onto an object to be coated to form a glitter coating film.
• the object to be coated with the glitter coating composition (Y) is not particularly limited.
• Examples of the object to be coated include the outer panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses; automobile parts such as bumpers; and the outer panels of household electrical appliances such as mobile phones and audio equipment. can. Among these, outer panels of automobile bodies and automobile parts are preferred.
• the materials of these objects to be coated are 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- Resins such as butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, and epoxy resin; plastic materials such as various FRP; inorganic materials such as glass, cement, and concrete; wood ; Examples include fibrous materials such as paper and cloth. Among these, metal materials and plastic materials are preferred.
• Surfaces to which multi-layer coatings are applied include phosphate treatment, chromate treatment, The material may be subjected to surface treatment such as surface treatment or complex oxide treatment.
• a coating film may be further formed on the object, which may or may not be surface-treated.
• the base material to be coated may be optionally subjected to surface treatment, and an undercoat film and/or intermediate coat film may be formed thereon.
• the undercoat film and/or intermediate coat film is, for example, when the object to be coated is an automobile body, a coating composition for undercoat and/or intermediate coat known per se that is commonly used in the painting of automobile bodies. It can be formed using objects.
• the undercoat paint composition for forming the above-mentioned undercoat film for example, an electrodeposition paint, preferably a cationic electrodeposition paint can be used.
• the intermediate coating composition for forming the intermediate coating film includes 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 such as a carboxyl group or a hydroxyl group; A coating made of an amino resin such as a melamine resin or a urea resin, or a crosslinking agent such as an optionally blocked polyisocyanate compound together with a pigment, a thickener, and other optional components can be used. .
• the glitter paint composition (Y) is a glitter paint composition containing indium particles (y1).
• the glitter coating composition (Y) preferably contains indium particles (y1), and further contains a surface conditioner, and water and/or an organic solvent.
• the indium particles (y1) are flaky particles.
• the flaky particles may also be referred to as scale particles, tabular particles, flake particles, or the like.
• a flaky particle means a particle having a substantially flat surface and having a substantially uniform thickness in the direction perpendicular to the substantially flat surface.
• the term "flake-like particles” refers to particles having a very thin thickness and a substantially flat surface having a very long length. Note that the length of the substantially flat surface is the diameter of a circle having the same projected area as the flaky particle.
• the shape of the substantially flat surface is not particularly limited and can be selected as appropriate depending on the purpose, for example, substantially rectangular, substantially square, substantially circular, substantially oval, substantially triangular, substantially quadrilateral, substantially pentagonal, and substantially Examples include polygons such as hexagons, approximately heptagons, and approximately octagons, and random irregular shapes. Among these, a substantially circular shape is preferable.
• the indium particles (y1) may have a single layer, or two or more layers may be laminated to form a primary particle. Moreover, the primary particles of the indium particles (y1) may aggregate to form secondary particles.
• the indium particles (y1) are made of indium with a purity of 95% or more, and may contain trace amounts of impurities, but do not contain alloys with other metals.
• the above indium particles (y1) can be manufactured by performing a peeling layer forming step, a vacuum evaporation step, a peeling step, and further other steps as necessary.
• the release layer forming step is a step of providing a release layer on the base material.
• the above-mentioned base material is not particularly limited as long as it has a smooth surface, and various materials can be used.
• resin films, metal foils, and composite films of metal foils and resin films having flexibility, heat resistance, solvent resistance, and dimensional stability can be used as appropriate.
• the resin film include polyester film, polyethylene film, polypropylene film, polystyrene film, and polyimide film.
• the metal foil include copper foil, aluminum foil, nickel foil, iron foil, and alloy foil.
• composite films of metal foil and resin film include those obtained by laminating the above resin film and metal foil.
• the peeling layer various organic substances that can be dissolved in the subsequent peeling process can be used. It is preferable to appropriately select the organic material constituting the release layer, since the organic material attached and remaining on the adhesion surface of the island-like structure film can function as a protective layer for the indium particles (y1).
• the protective layer has a function of suppressing agglomeration, oxidation, elution into a solvent, etc. of the indium particles (y1).
• Examples of organic substances constituting the release layer that can be used as a protective layer include cellulose acetate butyrate (CAB), other cellulose derivatives, polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyacrylic acid, polyacrylamide, and acrylic acid copolymers.
• Examples include polymerized nylon resins, modified nylon resins, polyvinylpyrrolidone, urethane resins, polyester resins, polyether resins, and alkyd resins. These may be used alone or in combination of two or more.
• cellulose acetate butyrate (CAB) is preferred because of its high functionality as a protective layer.
• the method for forming the release layer is not particularly limited and can be appropriately selected depending on the purpose, for example, an inkjet method, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method. , knife coating method, air knife coating method, comma coating method, U comma coating method, AKKU coating method, smoothing coating method, micro gravure coating method, reverse roll coating method, 4 roll coating method, 5 roll coating method, dip coating method, curtain coating method, slide coating method, die coating method, etc. These may be used alone or in combination of two or more.
• the vacuum deposition step is a step of vacuum depositing a metal layer containing indium particles (y1) on the release layer.
• the average deposition thickness of the metal layer containing indium particles (y1) is preferably 60 nm or less, more preferably 55 nm or less, even more preferably 50 nm or less, and particularly preferably 45 nm or less. Note that the average deposition thickness of the metal layer containing the indium particles (y1) is the same as the average thickness of the indium particles (y1).
• the average deposition thickness of the metal layer is 60 nm or less, there is an advantage that the surface roughness Ra of the coating film is reduced and excellent metallic gloss can be expressed.
• the average deposition thickness is the average value obtained by observing a cross section of the metal layer using, for example, a scanning electron microscope (SEM) and measuring the thickness of the metal layer at 5 to 10 locations.
• the metal layer is an island-like structured film.
• the island structure film can be formed by various methods such as vacuum evaporation, sputtering, and plating. Among these, the vacuum evaporation method is preferred.
• the vacuum evaporation method is preferable to the plating method in that it can form a film even on resin substrates and does not produce waste liquid, and is preferable to the plating method in that it can achieve a higher degree of vacuum and has a faster film formation rate (evaporation rate). preferable to law.
• the vapor deposition rate in the vacuum evaporation method is preferably 10 nm/sec or more, more preferably 10 nm/sec or more and 80 nm/sec or less.
• the peeling process is a process of peeling the metal layer from the base material by dissolving the peeling layer.
• the solvent that can dissolve the release layer is not particularly limited as long as it is a solvent that can dissolve the release layer, and can be appropriately selected depending on the purpose, but it may be used as it is as a solvent for the glitter coating composition (Y). Those that can be used are preferred.
• solvents that can dissolve the release layer include alcohol solvents such as methanol, ethanol, propanol, isopropanol, butanol, octanol, dodecanol, ethylene glycol, and propylene glycol; ether solvents such as tetrahydrone; acetone, methyl ethyl ketone, Ketone solvents such as acetylacetone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, phenyl acetate; ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol Monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether,
• Phenolic solvents aliphatic or aromatic such as pentane, hexane, heptane, octane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, octadecane, octadecene, benzene, toluene, xylene, trimesine, nitrobenzene, aniline, methoxybenzene, trimesine, etc.
• aliphatic or aromatic such as pentane, hexane, heptane, octane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, octadecane, octadecene, benzene, toluene, xylene, trimesine, nitrobenzene, aniline, methoxybenzene
• Hydrocarbon solvents aliphatic or aromatic chlorinated hydrocarbon solvents such as dichloromethane, chloroform, trichloroethane, chlorobenzene, dichlorobenzene; sulfur-containing compound solvents such as dimethyl sulfoxide; dimethylformamide, dimethylacetamide, acetonitrile, propionitrile, Examples include nitrogen-containing compound solvents such as benzonitrile. These may be used alone or in combination of two or more.
• the island-like structure film is separated from the base material, the island-like structure is split, and the individual islands become indium particles (y1).
• an indium particle (y1) dispersion can be obtained without any particular pulverization step, but the primary particles of indium particles (y1) may be pulverized and classified as necessary. Moreover, when the primary particles of the indium particles (y1) are aggregated, they may be crushed as necessary.
• various treatments may be performed to recover the indium particles (y1) and adjust the physical properties.
• the particle size of the indium particles (y1) may be adjusted by classification, the indium particles (y1) may be recovered by methods such as centrifugation or suction filtration, or the solid content concentration of the dispersion may be adjusted. good.
• solvent substitution may be performed, and viscosity adjustment may be performed using additives.
• ⁇ Other processes> Other steps include, for example, a step of taking out the peeled metal layer as a dispersion liquid, a step of recovering the island-shaped metal layer from the dispersion liquid as indium particles (y1), and the like.
• the cumulative 50% volume particle diameter D50 of the indium particles (y1) obtained by performing the above-mentioned release layer forming step, vacuum evaporation step, peeling step, and other steps as necessary has an excellent metallic luster. From the viewpoint of forming a multilayer coating film having It is particularly preferable.
• indium particles (y1) commercially available products can be used. Examples of such commercial products include “Leaf Powder 49CJ-1120”, “Leaf Powder 49CJ-1150”, “Leaf Powder 49BJ-1120”, and “Leaf Powder 49BJ-1150” (all manufactured by Oike Kogyo Co., Ltd.). Can be mentioned.
• the content of indium particles (y1) in the glitter coating composition (Y) of the present invention is determined by adjusting the solid content of 100 parts by mass of the glitter coating composition (Y) from the viewpoint of obtaining a coating film with excellent metallic gloss.
• it is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, even more preferably in the range of 80 to 99.9 parts by mass, and even more preferably in the range of 90 to 99.9 parts by mass.
• the surface conditioning agents include surface conditioning agents such as silicone surface conditioning agents, acrylic surface conditioning agents, vinyl surface conditioning agents, fluorine surface conditioning agents, and acetylene diol surface conditioning agents. From the viewpoint of obtaining a coating film with excellent gloss control, it is preferable to include a fluorine-based surface conditioner.
• the above-mentioned surface conditioners can be used alone or in an appropriate combination of two or more.
• fluorine-based surface conditioner examples include fluorine-based polymers and fluorine-based oligomers having perfluoroalkyl groups and polyalkylene oxide groups, fluorine-based polymers and fluorine-based oligomers having perfluoroalkyl ether groups and polyalkylene oxide groups Oligomers can be mentioned.
• the content is determined by the solid content of the glitter coating composition (Y) from the viewpoint of obtaining a coating film with excellent metallic gloss. Based on 100 parts by mass, it is preferably 0.01 to 2.0 parts by mass, more preferably 0.05 to 1.5 parts by mass, and 0.1 to 1.0 parts by mass. is even more preferable.
• organic solvent those commonly used in paints can be used. Specifically, for example, alcohol solvents such as methanol, ethanol, propanol, isopropanol, butanol, octanol, dodecanol, ethylene glycol, and propylene glycol; ether solvents such as tetrahydrone; ketone solvents such as acetone, methyl ethyl ketone, and acetylacetone.
• alcohol solvents such as methanol, ethanol, propanol, isopropanol, butanol, octanol, dodecanol, ethylene glycol, and propylene glycol
• ether solvents such as tetrahydrone
• ketone solvents such as acetone, methyl ethyl ketone, and acetylacetone.
• Ester solvents such as methyl acetate, ethyl acetate, butyl acetate, phenyl acetate; Ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol Monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, Glycol ether solvents such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether
• the organic solvent preferably contains at least one solvent selected from glycol ether-based organic solvents and alcohol-based organic solvents, from the viewpoint of obtaining a coating film with excellent metallic gloss. It is even more preferable.
• the content should be determined based on the sum of all components of the glitter coating composition (Y) from the viewpoint of obtaining a coating film with excellent metallic gloss. It is preferably within the range of 85 to 99.9 parts by mass, more preferably within the range of 90 to 99.5 parts by mass, and preferably within the range of 95 to 99 parts by mass relative to 100 parts by mass. It is even more preferable.
• the glitter coating composition (Y) may optionally include pigments other than indium particles (y1), viscosity modifiers, binder resins, crosslinking components, pigment dispersants, antisettling agents, and ultraviolet absorbers. A light stabilizer and the like may be added as appropriate.
• pigments other than the indium particles (y1) include colored pigments, glitter pigments other than the indium particles (y1), extender pigments, and the like. These pigments can be used alone or in combination of two or more.
• the color pigments include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, and perylene pigments. , dioxazine pigments, diketopyrrolopyrrole pigments, and the like.
• Examples of the glitter pigment other than the indium particles (y1) include vapor-deposited metal flake pigments other than the indium particles (y1), aluminum flake pigments, optical interference pigments, and the like.
• Examples of the extender pigment include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white.
• the content is determined from the viewpoint of obtaining a coating film with excellent metallic gloss. Based on 100 parts by mass of solid content of Y), it is preferably within the range of 0.01 to 30 parts by mass, more preferably within the range of 0.05 to 20 parts by mass, and 0.1 to 15 parts by mass. It is more preferably within the range of parts by mass.
• viscosity modifier examples include silica-based fine powder, mineral-based viscosity modifier, barium sulfate atomized powder, polyamide-based viscosity modifier, organic resin fine particle viscosity modifier, diurea-based viscosity modifier, and urethane-based viscosity modifier. acrylic swelling type polyacrylic acid-based viscosity modifiers, cellulose-based viscosity modifiers, and the like.
• binder resin examples include hydroxyl group-containing resin (y2).
• the above hydroxyl group-containing resin (y2) is a resin having at least one hydroxyl group in one molecule.
• the hydroxyl group-containing resin (y2) a wide variety of known resins can be used, such as acrylic resins having hydroxyl groups, polyester resins having hydroxyl groups, acrylic modified polyester resins having hydroxyl groups, polyether resins having hydroxyl groups, and polycarbonates having hydroxyl groups. Examples include resins such as polyurethane resins having hydroxyl groups, epoxy resins having hydroxyl groups, and alkyd resins having hydroxyl groups. These can be used alone or in combination of two or more. Among these, the hydroxyl group-containing resin (y2) preferably contains a hydroxyl group-containing acrylic resin (y2-1) from the viewpoint of adhesion of the formed coating film.
• the hydroxyl group-containing acrylic resin (y2-1) can be produced, for example, by copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers (polymerizable unsaturated monomers other than the hydroxyl group-containing polymerizable unsaturated monomer). Obtainable.
• the above-mentioned hydroxyl group-containing polymerizable unsaturated monomer is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated bonds in one molecule.
• Examples of the hydroxyl group-containing polymerizable unsaturated monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
• Monoesterified product of (meth)acrylic acid and dihydric alcohol having 2 to 8 carbon atoms ⁇ -caprolactone modified product of monoesterified product of (meth)acrylic acid and dihydric alcohol containing 2 to 8 carbon atoms
• ( Adducts of meth)acrylic acid and epoxy group-containing compounds for example, "Cardura E10P” (trade name), manufactured by Momentive Specialty Chemicals, neodecanoic acid glycidyl ester); N-hydroxymethyl (meth)acrylamide; allyl alcohol; , (meth)acrylate having a polyoxyethylene chain whose molecular terminal is a hydroxyl group, and the like.
• polymerizable unsaturated monomers that can be copolymerized with the above hydroxyl group-containing polymerizable unsaturated monomer, for example, the monomers shown in (1) to (6) below can be used. These polymerizable unsaturated monomers can be used alone or in combination of two or more.
• Acid group-containing polymerizable unsaturated monomer is a compound having one or more acid groups and one or more polymerizable unsaturated bonds in one molecule.
• the monomer include carboxyl group-containing monomers such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid and maleic anhydride; sulfonic acid group-containing monomers such as vinylsulfonic acid and 2-sulfoethyl (meth)acrylate.
• Acidic acids such as 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxypropyl acid phosphate, 2-(meth)acryloyloxy-3-chloropropyl acid phosphate, 2-methacryloyloxyethyl phenyl phosphate, etc.
• Examples include phosphoric acid ester monomers. These can be used alone or in combination of two or more.
• Esterified products of acrylic acid or methacrylic acid and monohydric alcohol having 1 to 20 carbon atoms Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, ) acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, isostearyl acrylate, lauryl ( Examples include meth)acrylate, tridecyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, cyclohexyl(meth)acrylate, isobornyl(meth)acrylate, and the like.
• Aromatic vinyl monomer Specific examples include styrene, ⁇ -methylstyrene, vinyltoluene, and the like.
• the glass transition temperature of the resulting resin increases, and a hydrophobic coating film with a high refractive index can be obtained, which improves the finished appearance by improving the gloss of the coating film. It is possible to obtain the improvement effect of
• an aromatic vinyl monomer When used as a constituent component, its blending ratio is preferably 3 to 50% by mass, particularly preferably 5 to 40% by mass, based on the total amount of monomer components.
• a glycidyl group-containing polymerizable unsaturated monomer is a compound having one or more glycidyl groups and one or more polymerizable unsaturated bonds in one molecule. Acrylate, glycidyl methacrylate, etc. can be mentioned.
• Polymerizable unsaturated bond-containing nitrogen atom-containing compound for example, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-[3-(dimethylamino)propyl](meth)acrylamide, N-butoxymethyl
• one or more of the monomers shown in (1) to (6) above can be used.
• the polymerizable unsaturated monomer refers to a monomer having one or more (for example, 1 to 4) polymerizable unsaturated groups.
• a polymerizable unsaturated group means an unsaturated group that can undergo radical polymerization. Examples of such polymerizable unsaturated groups include vinyl group, (meth)acryloyl group, (meth)acrylamide group, vinyl ether group, allyl group, propenyl group, isopropenyl group, and maleimide group.
• (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 hydroxyl value of the hydroxyl group-containing acrylic resin (y2-1) is preferably from 30 to 200 mgKOH/g, more preferably from 40 to 180 mgKOH/g, from the viewpoint of curability and water resistance, and more preferably from 50 to 180 mgKOH/g. Particularly preferred is a range of 150 mgKOH/g.
• the acid value of the hydroxyl group-containing acrylic resin (y2-1) is preferably 0.5 to 15 mgKOH/g, more preferably 1 to 12 mgKOH/g, from the viewpoint of curability and water resistance, etc. Particularly preferred is a range of 2 to 10 mgKOH/g.
• the weight average molecular weight of the hydroxyl group-containing acrylic resin (y2-1) is preferably within the range of 2,000 to 50,000, and 3,000 to 45, from the viewpoint of finished appearance and curability of the coating film. ,000, and even more preferably 5,000 to 40,000.
• the average molecular weight is a value calculated from a chromatogram measured by gel permeation chromatography based on the molecular weight of standard polystyrene.
• a gel permeation chromatograph "HLC8120GPC” (manufactured by Tosoh Corporation) was used. Four columns were used: “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, and “TSKgel G-2000HXL” (all manufactured by Tosoh Corporation, product names), and the mobile phase
• the measurement was carried out under the following conditions: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 cc/min, detector: RI.
• the glass transition temperature of the hydroxyl group-containing acrylic resin (y2-1) is preferably -50 to 60°C, more preferably -20 to 50°C, from the viewpoint of the hardness of the coating film and the finished appearance, etc. Particularly preferred is a temperature range of 0 to 45°C.
• the glass transition temperature (°C) of the acrylic resin was calculated using the following formula.
• T1, T2, . . . are values according to Polymer Hand Book (Second Edition, edited by J. Brandup and E.H. Immergut) III-139 to 179.
• the glass transition temperature (°C) is determined as the static glass transition temperature, and for example, using a differential scanning calorimeter "DSC-220U” (manufactured by Seiko Instruments Inc.), After placing the sample in a measuring cup and completely removing the solvent by vacuum suction, the change in calorific value was measured in the range of -20°C to +200°C at a heating rate of 3°C/min. The point of change was defined as the static glass transition temperature.
• DSC-220U differential scanning calorimeter
• the copolymerization method for copolymerizing the above monomer mixture to obtain the hydroxyl group-containing acrylic resin (y2-1) is not particularly limited, and any known copolymerization method can be used.
• a solution polymerization method in which polymerization is carried out in an organic solvent in the presence of a polymerization initiator can be suitably used.
• organic solvents used in the solution polymerization method include aromatic solvents such as toluene, xylene, and Swasol 1000 (manufactured by Cosmo Oil Co., Ltd., trade name, high-boiling petroleum solvent); ethyl acetate, butyl acetate, Ester solvents such as propylpropionate, butylpropionate, 1-methoxy-2-propyl acetate, 2-ethoxyethylpropionate, 3-methoxybutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate;
• Examples include ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone, and alcohol solvents such as isopropanol, n-butanol, isobutanol, and 2-ethylhexanol.
• organic solvents can be used alone or in combination of two or more, but from the viewpoint of solubility of the acrylic resin, it is preferable to use ester-based solvents and ketone-based solvents. Furthermore, aromatic solvents may be suitably combined with these organic solvents.
• polymerization initiators examples include 2,2'-azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, di-t- - Known radical polymerization initiators such as amyl peroxide, t-butyl peroctoate, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), etc. can be mentioned.
• the glitter coating composition (Y) of the present invention contains a hydroxyl group-containing acrylic resin (y2-1) as the hydroxyl group-containing resin (y2)
• the content is such that it has excellent metallic gloss and From the viewpoint of forming a multilayer coating film exhibiting excellent coating film performance such as adhesion, it is preferably within the range of 50 to 100% by mass, based on the solid content of the hydroxyl group-containing resin (y2), and 55 It is more preferably within the range of ⁇ 100% by mass, and even more preferably within the range of 60 ⁇ 100% by mass.
• the content is such that it has excellent metallic gloss and excellent coating film performance such as adhesion.
• the amount is preferably within the range of 0.1 to 15 parts by mass, and 0.5 to 15 parts by mass, based on 100 parts by mass of the solid content of the glitter coating composition (Y). It is more preferably within the range of 12 parts by mass, and even more preferably within the range of 1 to 10 parts by mass.
• crosslinkable component examples include melamine resin (y3), melamine resin derivatives, urea resins, (meth)acrylamide, polyaziridine, polycarbodiimide, and polyisocyanate compounds that may or may not be blocked.
• melamine resin (y3) it is preferable to include melamine resin (y3) from the viewpoint of adhesion of the formed coating film.
• melamine resin (y3) a partially methylolated melamine resin or a fully methylolated melamine resin obtained by a reaction between a melamine component and an aldehyde component can be used.
• aldehyde component include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.
• the melamine resin (y3) it is also possible to use one in which the methylol group of the above-mentioned methylolated melamine resin is partially or completely etherified with an appropriate alcohol.
• the alcohol used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethyl-1-butanol, 2-ethyl-1 -Hexanol, etc.
• the melamine resin (y3) is a methyl etherified melamine resin in which the methylol groups of a partially or completely methylolated melamine resin are partially or completely etherified with methyl alcohol, and a methyl etherified melamine resin in which the methylol groups of a partially or fully methylolated melamine resin are partially or completely etherified with butyl alcohol.
• butyl etherified melamine resin partially or completely etherified with methyl alcohol and butyl alcohol
• methyl-butyl mixed etherified melamine resin partially or completely etherified with methyl alcohol and butyl alcohol.
• methyl-butyl mixed etherified melamine resin is more preferable.
• the weight average molecular weight of the melamine resin (y3) is preferably 400 to 6,000, more preferably 500 to 4,000, and even more preferably 600 to 3,000.
• the content is such that it has excellent metallic luster and exhibits excellent coating performance such as adhesion.
• the content is preferably within the range of 0.1 to 10 parts by mass, and 0.3 to 8 parts by mass, based on 100 parts by mass of the solid content of the glitter coating composition (Y). It is more preferably within the range of 0.5 to 5 parts by mass, and even more preferably within the range of 0.5 to 5 parts by mass.
• Coating with the glitter coating composition (Y) can be carried out according to a conventional method, and examples include methods such as air spray coating, airless spray coating, and rotary atomization coating.
• electrostatic charge may be optionally applied.
• electrostatic coating using a rotary atomization method and electrostatic coating using an air spray method are preferable. Particularly preferred is the electrostatic coating method.
• the glitter coating composition (Y) may contain water and/or an organic solvent and optionally additives such as an antifoaming agent. It is preferable to adjust the solid content and viscosity to be suitable for coating.
• the solid content of the glitter coating composition (Y) of the present invention is determined from the viewpoint of forming a multilayer coating film that has excellent metallic gloss and exhibits excellent coating film performance such as adhesion.
• the content is preferably from 0.1 to 15% by weight, preferably from 0.5 to 10% by weight, and more preferably from 1 to 5% by weight.
• the viscosity of the glitter coating composition (Y) is Ford Cup No. 1 from the viewpoint of forming a multilayer coating film that has excellent metallic gloss and exhibits excellent coating film performance such as adhesion.
• the time at 20° C. is preferably about 8 to 30 seconds, particularly preferably about 10 to 25 seconds.
• the cured film thickness of the bright coating film is preferably about 0.01 to 2 ⁇ m from the viewpoint of forming a multilayer coating film that has excellent metallic luster and exhibits excellent coating performance such as adhesion. , more preferably about 0.025 to 1 ⁇ m, still more preferably about 0.05 to 0.5 ⁇ m.
• a clear coating composition containing a hydroxyl group-containing acrylic resin (z1) and a polyisocyanate compound (z2) is applied on the glitter coating film obtained in step (1).
• the object (Z) is painted and a clear coating film is formed.
• the hydroxyl group-containing acrylic resin (z1) is an acrylic resin having at least one hydroxyl group in one molecule, and has a hydroxyl value within the range of 10 to 75 mgKOH/g. If the content of the hydroxyl group-containing acrylic resin (z1) is less than 10 mgKOH/g, the adhesion of the multilayer coating film to be formed will be poor. If the amount of the hydroxyl group-containing acrylic resin (z1) exceeds 75 mgKOH/g, the adhesion of the multilayer coating film formed will deteriorate.
• the hydroxyl value of the hydroxyl group-containing acrylic resin (z1) is within the range of 12 to 70 mgKOH/g from the viewpoint of adhesion of the multilayer coating film to be formed and compatibility with the polyisocyanate compound (z2). It is preferably within the range of 15 to 65 mgKOH/g, and more preferably within the range of 15 to 65 mgKOH/g.
• the hydroxyl group-containing acrylic resin (z1) can be obtained by, for example, using a hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers (polymerizable unsaturated monomers other than the hydroxyl group-containing polymerizable unsaturated monomer) by a method known per se. For example, it can be produced by copolymerization using a solution polymerization method in an organic solvent, an emulsion polymerization method in water, or the like.
• hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers the compounds described in the description column of hydroxyl group-containing acrylic resin (y2-1) can be used.
• the weight average molecular weight of the hydroxyl group-containing acrylic resin (z1) is preferably in the range of 2,000 to 50,000, preferably 3,000 to 45, from the viewpoint of adhesion of the multilayer coating film to be formed. ,000, and even more preferably 5,000 to 40,000.
• the acid value of the hydroxyl group-containing acrylic resin (z1) is 30 mgKOH/g or less, especially 1 to 20 mgKOH, from the viewpoint of the finished appearance of the multilayer coating film to be formed, adhesion, and the pot life of the clear paint composition (Z). It is preferably within the range of /g.
• the glass transition temperature of the hydroxyl group-containing acrylic resin (z1) is preferably -50 to 60°C, more preferably -30 to 50°C, from the viewpoint of adhesion, chipping resistance, finished appearance, etc. of the multilayer coating film to be formed. °C, particularly preferably within the range of -10 to 45 °C.
• organic solvent used in the above solution polymerization method examples include alcohol solvents such as methanol, ethanol, propanol, isopropanol, butanol, octanol, dodecanol, ethylene glycol, and propylene glycol; ether solvents such as tetrahydrone; acetone; Ketone solvents such as methyl ethyl ketone and acetylacetone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, and phenyl acetate; ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, di
• polymerization initiators examples include 2,2'-azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, and di-t-amyl.
• Known radical polymerization initiators such as peroxide, t-butyl peroctoate, 2,2'-azobis(2-methylbutyronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile) are listed. be able to.
• the above hydroxyl group-containing acrylic resin (z1) can be used alone or in combination of two or more.
• Polyisocyanate compound (z2) is a compound having at least two isocyanate groups in one molecule, and includes, for example, aliphatic polyisocyanate, alicyclic polyisocyanate, araliphatic polyisocyanate, aromatic polyisocyanate, etc. Examples include derivatives of 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, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate); 2 , 2-isocyanatoethyl 6-diisocyanatohexanoate, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1
• 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), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, 1,3- or 1,4-bis(isocyanate) Alicyclic diisocyanates such as methyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or mixtures thereof, methylenebis(4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), norbornane diisocyanate; 1,3,5 -triisocyanatocycl
• araliphatic polyisocyanate examples include methylene bis(4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ⁇ , ⁇ '-diisocyanato- Aroaliphatic diisocyanates such as 1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; 1,3 , 5-triisocyanatomethylbenzene and other aromatic aliphatic triisocyanates.
• MDI methylene bis(4,1-phenylene) diisocyanate
• 1,3- or 1,4-xylylene diisocyanate or a mixture thereof ⁇ , ⁇ '-diisocyanato- Aroaliphatic diisocyanates
• aromatic polyisocyanate examples include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4- Aromatic diisocyanates such as 2,6-tolylene diisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate; triphenylmethane-4 , 4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene; 4,4'-diphenylmethane-2,2' , 5,5'-tetraisocyanate and other aromatic tetraisocyanates.
• 2,4- Aromatic diisocyanates such as 2,6-
• polyisocyanate derivatives examples include the above-mentioned polyisocyanate dimer, trimer, biuret, allophanate, uretdione, uretimine, isocyanurate, oxadiazinetrione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI), crude Examples include TDI.
• the above polyisocyanates and their derivatives may be used alone or in combination of two or more.
• aliphatic diisocyanates hexamethylene diisocyanate-based compounds and among the alicyclic diisocyanates, 4,4'-methylenebis(cyclohexyl isocyanate) can be preferably used.
• derivatives of hexamethylene diisocyanate are particularly suitable from the viewpoints of adhesion, compatibility, and the like.
• the polyisocyanate compound (z2) As the polyisocyanate compound (z2), the polyisocyanate and its derivatives are reacted with a compound having an active hydrogen group such as a hydroxyl group or an amino group, which can react with the polyisocyanate, under conditions where there are an excess of isocyanate groups.
• polyisocyanate compound (z2) it is also possible to use a blocked polyisocyanate compound, which is a compound in which the isocyanate groups in the above polyisocyanate and its derivatives are blocked with a blocking agent.
• the blocking agent examples include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; ⁇ -caprolactam, ⁇ -valerolactam, Lactams such as ⁇ -butyrolactam and ⁇ -propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono Ethers such as butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate
• Oxime series active methylene series such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thio Mercaptans such as phenol, methylthiophenol and ethylthiophenol; acidamides such as acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetamide, stearamide and benzamide; succinimide, phthalimide, maleimide, etc.
• active methylene series such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone
• amine series such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine; imidazole series such as imidazole, 2-ethylimidazole; urea, thio Urea types such as urea, ethylene urea, ethylene thiourea, and diphenyl urea; Carbamate ester types such as phenyl N-phenylcarbamate; Imine types such as ethylene imine and propylene imine; Sulfite types such as sodium bisulfite and potassium bisulfite.
• Examples include azole compounds.
• Examples of the azole compounds include pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3, Pyrazole or pyrazole derivatives such as 5-dimethylpyrazole, 3-methyl-5-phenylpyrazole; imidazole or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole; 2-methylimidazoline and imidazoline derivatives such as 2-phenylimidazoline.
• a solvent can be optionally added.
• the polyisocyanate compounds (z2) can be used alone or in combination of two or more.
• the equivalent ratio (NCO/OH) between the total mol of isocyanate groups of the polyisocyanate compound (z2) and the total mol of hydroxyl groups of the hydroxyl group-containing acrylic resin (z1) is determined by From the viewpoint of forming a multilayer coating film exhibiting excellent coating performance, it is preferably within the range of 0.70 to 1.50, more preferably within the range of 0.75 to 1.40, More preferably, it is within the range of 0.8 to 1.20.
• the clear coating composition (Z) optionally contains a solvent such as water and an organic solvent, a resin other than the hydroxyl group-containing acrylic resin (z1), a curing agent other than the polyisocyanate compound (z2), a curing catalyst, and an antifoaming agent.
• a solvent such as water and an organic solvent
• a resin other than the hydroxyl group-containing acrylic resin (z1) a curing agent other than the polyisocyanate compound (z2)
• a curing catalyst e.g., a curing catalyst
• an antifoaming agent e.g., ultraviolet absorbers, rheology control agents, antisettling agents, and other paint additives may be appropriately blended.
• color pigments can be used as appropriate within the range that does not impair the transparency of the coating film.
• coloring pigment pigments known per se for use in inks or paints can be used alone or in combination of two or more.
• the blending amount varies depending on the type of coloring pigment used, etc., but is usually 30% by mass or less, preferably 0.05 to 20% by mass, based on the total solid content of the resin component of the clear paint composition (Z). %, more preferably within the range of 0.1 to 10% by weight.
• the clear coating composition (Z) can be applied by electrostatic coating, air spraying, airless spraying, etc., and the thickness of the clear coating film is preferably about 10 to 60 ⁇ m based on the cured coating film. The thickness is about 15 to 50 ⁇ m, more preferably about 20 to 40 ⁇ m.
• the solid content of the clear coating composition (Z) is within the range of 10 to 65% by mass, preferably 15 to 55% by mass, and more preferably 20 to 50% by mass.
• the viscosity of the clear paint composition (Z) is adjusted to a range suitable for painting, usually Ford Cup No. Using water and/or an organic solvent, adjust as appropriate so that the time is preferably within the range of about 15 to 60 seconds, particularly preferably about 20 to 50 seconds, at 20° C. using a viscometer.
• Process (3) According to the method for forming a multilayer coating film of the present invention, next, the glitter coating film formed in the step (1) and the clear coating film formed in the step (2) are heated separately or simultaneously. to harden it.
• the heating means can be, for example, hot air heating, infrared heating, high frequency heating, etc.
• the heating temperature is preferably 80 to 160°C, more preferably 100 to 140°C.
• the heating time is preferably 10 to 60 minutes, more preferably 15 to 40 minutes.
• heating may be performed before performing the heat curing, directly or indirectly, for about 1 to 60 minutes, preferably at a temperature of about 50 to about 110 °C, more preferably about 60 to about 90 °C, by preheating, air blowing, etc. Heating may be performed.
• the present invention also includes the following embodiments.
• Item 1 The following steps (1) to (3): Step (1): a step of coating a glittering paint composition (Y) containing indium particles (y1) on the object to be coated to form a glittering coating film; Step (2): A clear coating composition (Z) containing a hydroxyl group-containing acrylic resin (z1) and a polyisocyanate compound (z2) is applied onto the glitter coating film obtained in step (1) to form a clear coating.
• Step (3) of forming a film Curing the glitter coating formed in step (1) and the clear coating formed in step (2) by heating them separately or simultaneously.
• a method for forming a multilayer coating film comprising the steps of: A method for forming a multilayer coating film, wherein the hydroxyl value of the hydroxyl group-containing acrylic resin (z1) is within the range of 10 to 75 mgKOH/g.
• Item 2. The method for forming a multilayer coating according to Item 1, wherein the glitter coating composition (Y) further contains a hydroxyl group-containing resin (y2).
• Item 3. Item 3.
• the method for forming a multilayer coating according to item 1 or 2 wherein the glitter coating composition (Y) further contains a melamine resin (y3).
• the equivalent ratio (NCO/OH) of the total mol of isocyanate groups of the polyisocyanate compound (z2) to the total mol of hydroxyl groups of the hydroxyl group-containing acrylic resin (z1) is 0.7 to The method for forming a multilayer coating film according to any one of Items 1 to 3, which is within the range of 1.5.
• Item 5 Any of Items 1 to 4, wherein the content of indium particles (y1) in the glitter paint composition (Y) is 50 parts by mass or more based on 100 parts by mass of solid content of the glitter paint composition (Y).
• Item 10. 10 The method for forming a multilayer coating film according to item 9, wherein the surface conditioning agent contains a fluorine-based surface conditioning agent.
• Item 11. Item 11. The multilayer coating according to Item 9 or 10, wherein the content of the surface conditioner is within the range of 0.01 to 0.2 parts by mass based on 100 parts by mass of the solid content of the glitter coating composition (Y). Film formation method.
• a cationic electrodeposition paint "Electron GT-10" (trade name: Kansai Paint Co., Ltd., epoxy resin polyamine type) was applied to a degreased and zinc phosphate treated steel plate (JIS G3141, size 400 mm x 300 mm x 0.8 mm)
• a cationic resin using a block polyisocyanate compound as a curing agent was electrodeposited to a film thickness of 20 ⁇ m based on the cured coating, heated at 170°C for 20 minutes to crosslink and cure, and then electrodeposited. A film was formed.
• TP-65-2 (trade name, manufactured by Kansai Paint Co., Ltd., a polyester resin and amino resin-based organic solvent type intermediate coating composition) was applied to the electrodeposited surface of the obtained steel plate using a rotary atomization method. Using an electrostatic coating machine, electrostatic coating was applied so that the cured film thickness was 35 ⁇ m, and the coating was cured by heating at 140° C. for 30 minutes to form an intermediate coating film, thereby preparing a coated object.
• a mixed solution consisting of 0.5 part of di-tert-amyl peroxide and 8 parts of "Swazol 1000" was added dropwise over 1 hour, and after the addition was completed, the solid content was maintained at 125°C for 1 hour.
• a 60% hydroxyl group-containing acrylic resin solution (y2-1) was obtained.
• the obtained hydroxyl group-containing acrylic resin (y2-1-1) had a hydroxyl value of 82 mgKOH/g, an acid value of 5 mgKOH/g, a weight average molecular weight of 28,000, and a glass transition temperature of 17°C.
• Production examples 3 to 9 Glitter coating compositions (Y-2) to (Y-8) were obtained in the same manner as in Production Example 2 except that the formulation and solid content were as shown in Table 1.
• Production example 10 of hydroxyl group-containing acrylic resin (z1) In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, nitrogen inlet tube, and dropping device, 27 parts of "Swazol 1000" (trade name, manufactured by Cosmo Oil Co., Ltd., aromatic organic solvent) and propylene glycol were added. 5 parts of monomethyl ether acetate were charged.
• the charge solution was stirred at 150°C while blowing nitrogen gas into the reaction vessel, and 20 parts of styrene, 10.5 parts of n-butyl acrylate, 3.5 parts of 2-hydroxyethyl methacrylate, 50 parts of isobutyl methacrylate, and 2 -
• a monomer mixture consisting of 15 parts of ethylhexyl acrylate, 1.0 part of acrylic acid, and 1.5 parts of ditertiary amyl peroxide (polymerization initiator) was added dropwise at a uniform rate over 4 hours. Thereafter, the mixture was aged at 150° C.
• hydroxyl group-containing acrylic resin (z1-1) for 1 hour, cooled, and further diluted by adding 21 parts of isobutyl acetate to obtain a hydroxyl group-containing acrylic resin (z1-1) solution with a solid content concentration of 65% by mass.
• the obtained hydroxyl group-containing acrylic resin (z1-1) had a hydroxyl value of 15 mgKOH/g, an acid value of 8 mgKOH/g, a weight average molecular weight of 30,000, and a glass transition temperature of 24°C.
• Production examples 11 to 15 a solution of hydroxyl group-containing acrylic resins (z1-2) to (z1-6) with a solid content concentration of 65% by mass was prepared in the same manner as in Production Example 10, except that the composition was as shown in Table 2. Obtained. Table 2 also shows the acid value, hydroxyl value, weight average molecular weight, and glass transition temperature of each hydroxyl group-containing acrylic resin.
• Production examples 17 to 23 Clear coating compositions (Z-2) to (Z-8) were obtained in the same manner as in Production Example 16 except for using the formulations shown in Table 3.
• test board Creation of test board
• Example 1 The bright paint composition (Y-1) produced in the above "2. Preparation of the paint” was applied onto the base material prepared in the above "1. Preparation of the base material” using a mini-bell type rotary electrostatic coating machine. , under the conditions of a booth temperature of 23°C and humidity of 63%, the cured coating was applied to a film thickness of 0.05 ⁇ m, left at room temperature for 15 minutes, and then heated at 140°C in a hot air circulation drying oven. The mixture was heated for 30 minutes to dry and cure to obtain a glitter coating film.
• Example 1 A test plate was prepared.
• Example 2-7, 9-13 and Comparative Examples 1-3 A test plate was obtained in the same manner as in Example 1 except that the coating material and film thickness were as shown in Table 4.
• Example 8 The bright paint composition (Y-2) produced in "2. Preparation of paint” above was applied onto the base material prepared in "1. Preparation of base material” above using a mini-bell type rotary electrostatic coating machine. , under conditions of a booth temperature of 23°C and humidity of 63%, the cured coating was applied to a film thickness of 0.1 ⁇ m, left at room temperature for 15 minutes, and then heated to 80°C in a hot air circulation drying oven. Preheating was performed for 3 minutes to obtain an uncured glitter coating film.
• the clear paint composition (Z-2) prepared in "2. Preparation of Paint” above was applied onto the uncured glitter coating film using a mini-bell rotary electrostatic coating machine at a booth temperature of 23. °C and 68% humidity to give a cured coating film of 35 ⁇ m. After leaving it at room temperature for 7 minutes, it was heated at 140°C for 30 minutes in a hot air circulation drying oven to form a bright coating film.
• a test plate of Example 8 was prepared by drying and curing the clear coating film and the clear coating film at the same time.
• Coating film evaluation The coating film of each test plate obtained as described above was evaluated by the following method, and the results are shown in Table 4.
• test board was immersed in warm water at 40°C for 240 hours, pulled out, wiped with a cloth to remove water droplets and dirt, and within 10 minutes at a room temperature of 23°C, cut the multilayer coating on the test board to reach the substrate. Make 100 goblets of 2mm x 2mm in size by cutting in a grid pattern. Subsequently, an adhesive cellophane tape was attached to the surface, and after the tape was rapidly peeled off, the remaining state of the rough coating film was examined, and the water-resistant adhesion was evaluated according to the following criteria. A and B pass. A: 100 scratched coatings remain, and there are no small edge chips of the coating at the edges of the cutter's incisions.
• B 100 coating films remain, but small edges of the coating film are chipped at the edges of the cuts of the cutter, and there are less than 10 remaining coating films with chipped edges.
• C 100 coating films remain, but small edges of the coating film are chipped at the edges of the cuts of the cutter, and there are 10 or more remaining coating films with chipped edges.
• D 90 to 99 rough coating films remain.
• E The number of remaining rough coating films is 89 or less.

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