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
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
• • 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
• • 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
• • 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
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/20—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for coatings strippable as coherent films, e.g. temporary coatings strippable as coherent films

Definitions

• the present invention relates to a peelable aqueous coating composition for automobiles and a method for forming a multi-layer coating film.
• the above-mentioned peelable coating film is also used to decorate the exterior of a vehicle.
• the peelable coating film is easier to peel off than ordinary coating films, so the exterior of the vehicle can be easily changed.
• the exterior of the vehicle can be decorated by applying a peelable paint composition to the exterior surface of the vehicle and then applying a color base paint and/or clear paint on top of that.
• this can be done by removing the peelable coating film.
• the above-mentioned peelable coating film is required to have properties that make it difficult to peel off during normal use, yet easy to peel off when desired.
• Patent Document 1 describes a method for producing a poly(meth)acrylic ester-based resin particle gelatinized or dissolved in an aqueous medium, the method comprising the steps of: (a) dispersing poly(meth)acrylic ester-based resin particles in an aqueous medium; and (b) gelatinizing or dissolving sugars in the aqueous medium; the sugars are present in an amount of 1 to 100 parts by mass relative to 100 parts by mass of the poly(meth)acrylic ester-based resin particles; the average particle diameter of the poly(meth)acrylic ester-based resin particles is 5 to 100 ⁇ m; the sugars are at least one selected from the group consisting of starch, monosaccharides, oligosaccharides of 10 or less sugars, dextrin, and sugar alcohols; and the poly(meth)acrylic ester-based resin particles are derived from (meth)acrylic esters.
• the removable aqueous pressure-sensitive adhesive composition contains structural units derived from the (meth)acrylic ester and structural units derived from an unsaturated carboxylic acid monomer copolymerizable with the (meth)acrylic ester, and the total content of the structural units derived from the (meth)acrylic ester is 70 to 99.5% by mass and the content of the structural units derived from the unsaturated carboxylic acid monomer is 0.5 to 30% by mass, based on the total mass of the monomer components forming the poly(meth)acrylic ester resin particles, and is therefore more environmentally friendly and capable of forming a pressure-sensitive adhesive with excellent removable properties by contributing to an increase in biomass content.
• Patent Document 1 provides a removable aqueous pressure-sensitive adhesive composition with excellent removable properties, but it can be difficult to achieve both properties and adhesion to the substrate.
• the object of the present invention is to provide a peelable aqueous coating composition for automobiles that has a small environmental impact and can form a coating film that has excellent adhesion to substrates, peelability, and peelability after thermal stress.
• a peelable aqueous coating composition for automobiles which contains an acrylic urethane composite resin (A) containing a urethane resin portion (a1) and an acrylic resin portion (a2), and in which the constituent components of the acrylic urethane composite resin (A) contain plant-derived raw materials.
• a peelable aqueous coating composition for automobiles comprising an acrylic urethane composite resin containing a urethane resin portion (a1) and an acrylic resin portion (a2), A peelable aqueous coating composition for automobiles, wherein a constituent component of the acrylic urethane composite resin (A) contains a plant-derived raw material.
• the components of the urethane resin portion (a1) include a polyisocyanate component (a11) and a polyol component (a12), and the components of the polyol component (a12) include plant-derived raw materials.
• ⁇ 4> The peelable aqueous coating composition for automobiles according to any one of ⁇ 1> to ⁇ 3>, wherein a component of the acrylic resin portion (a2) contains a plant-derived raw material.
• ⁇ 5> The peelable aqueous coating composition for automobiles according to any one of ⁇ 1> to ⁇ 4>, further comprising an acrylic resin (B).
• ⁇ 6> The peelable aqueous coating composition for automobiles according to ⁇ 5>, wherein the constituent component of the acrylic resin (B) contains a polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule.
• the oligomer (C) is represented by the general formula (1)
• the peelable aqueous coating composition for automobiles according to ⁇ 7> comprising a diester compound (C1) represented by the following formula: ⁇ 9>
• Step (I-1) A step of applying a peelable automotive aqueous coating composition according to any one of ⁇ 1> to ⁇ 8> onto a substrate to form a peelable coating film
• Step (I-2) A step of drying the peelable coating film formed in the step (I-1)
• a method for forming a multilayer coating film comprising: step (I-3): applying a clear coat paint composition onto the peelable coating film formed in step (I-2) to form an uncured clear coat film; and step (I-4): heat-curing the uncured clear coat film formed in step (I-3).
• Step (II-1) A step of applying a peelable automotive aqueous coating composition according to any one of ⁇ 1> to ⁇ 8> on a substrate to form a peelable coating film;
• Step (II-2) A step of drying the peelable coating film formed in the step (II-1);
• Step (II-3) A step of applying a base coat paint composition onto the peelable coating film formed in the step (II-2) to form an uncured base coat coating film;
• a method for forming a multilayer coating film comprising: step (II-4): applying a clear coat paint composition onto the uncured base coat film formed in step (II-3) to form an uncured clear coat film; and step (II-5): heating and curing the uncured base coat film formed in step (II-3) and the uncured clear coat film formed in step (II-4) at the same time.
• the peelable aqueous coating composition for automobiles of the present invention can form a coating film that has a small environmental impact and is excellent in adhesion to the substrate, peelability, and peelability after thermal stress.
• the peelable aqueous coating composition for automobiles of the present invention is a peelable aqueous coating composition for automobiles comprising an acrylic urethane composite resin (A) containing a urethane resin portion (a1) and an acrylic resin portion (a2), wherein a component of the acrylic urethane composite resin (A) contains a plant-derived raw material.
• the acrylic urethane composite resin (A) contains a urethane resin portion (a1) and an acrylic resin portion (a2), and the constituent components of the acrylic urethane composite resin (A) include a plant-derived raw material.
• the acrylic urethane composite resin (A) contains a structural unit derived from a plant-derived raw material.
• the plant-derived raw material is preferably a compound derived from one or more kinds of plants, and more preferably a polymerizable compound derived from one or more kinds of plants.
• the biomass degree of the acrylic urethane composite resin (A) is the mass content of biologically derived raw materials in the acrylic urethane composite resin (A).
• the biologically derived raw materials include plant-derived raw materials. From the viewpoints of the environmental burden of the coating film formed and the manufacturing stability of the acrylic urethane composite resin (A), the biomass degree is preferably within the range of 5 to 95%, more preferably within the range of 10 to 90%, and even more preferably within the range of 15 to 75%.
• the above biomass degree can be calculated in accordance with the ISO 16620-4 standard.
• the acrylic urethane composite resin (A) can be produced by a conventionally known method for producing an acrylic urethane composite resin, but from the viewpoint of production stability, it is preferable to produce it by the following method (comprising the following production steps 1 to 3).
• the urethane resin portion (a1) is synthesized in the presence of a compound (a21) that has a polymerizable unsaturated group and has no hydroxyl group or one hydroxyl group, which is a component of the acrylic resin portion (a2).
• Production step 2 Next, deionized water is added to the mixture containing the urethane resin portion (a1) obtained in production step 1 and the compound (a21) having a polymerizable unsaturated group and either no hydroxyl group or one hydroxyl group, and emulsified to obtain an aqueous dispersion. If necessary, a chain extension reaction and desolvation are further carried out.
• Production step 3 Next, a polymerization initiator is added to the aqueous dispersion and a polymerization reaction is carried out to obtain an acrylic urethane composite resin (A) containing a urethane resin portion (a1) and an acrylic resin portion (a2).
• the urethane resin portion (a1) is synthesized in the presence of a compound (a21) which has a polymerizable unsaturated group and has no hydroxyl group or one hydroxyl group, and which is a component of the acrylic resin portion (a2).
• the components of the acrylic resin portion (a2) preferably contain plant-derived raw materials from the viewpoint of the environmental impact of the coating film formed.
• the compound (a21) having a polymerizable unsaturated group and no hydroxyl group or having one hydroxyl group preferably contains plant-derived raw materials.
• the compound (a21) having a polymerizable unsaturated group and no hydroxyl group or having one hydroxyl group includes a compound (a211) having a polymerizable unsaturated group and one hydroxyl group, and a compound (a212) having a polymerizable unsaturated group and no hydroxyl group.
• the above-mentioned compound (a211) having a polymerizable unsaturated group and one hydroxyl group includes a compound (a2111) having one polymerizable unsaturated group and one hydroxyl group, and a compound (a2112) having two or more polymerizable unsaturated groups and one hydroxyl group.
• Examples of the compound (a2111) having one polymerizable unsaturated group and one hydroxyl group include monoesters of (meth)acrylic acid and dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, as well as ⁇ -caprolactone-modified products of the monoesters, N-hydroxymethyl (meth)acrylamide, allyl alcohol, and hydroxyl-containing polymerizable unsaturated monomers, such as (meth)acrylates having a polyoxyethylene chain with a hydroxyl group at the molecular end.
• monoesters of (meth)acrylic acid and dihydric alcohols having 2 to 8 carbon atoms such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybut
• These compounds (a2111) having one polymerizable unsaturated group and one hydroxyl group can be used alone or in combination of two or more.
• Examples of the compound (a2112) having two or more polymerizable unsaturated groups and one hydroxyl group include glycerol di(meth)acrylate, 1,1,1-trishydroxymethylethane di(meth)acrylate, etc.
• These compounds (a2112) having two or more polymerizable unsaturated groups and one hydroxyl group can be used alone or in combination of two or more.
• the content of the compound (a211) having a polymerizable unsaturated group and one hydroxyl group is preferably within the range of 1 to 50 mass%, more preferably within the range of 2 to 40 mass%, and even more preferably within the range of 5 to 30 mass%, based on the total solid content of the compound (a21) having a polymerizable unsaturated group and no hydroxyl group or one hydroxyl group, from the viewpoint of production stability, etc.
• the compound (a212) having a polymerizable unsaturated group and no hydroxyl group includes a compound (a2121) having one polymerizable unsaturated group and no hydroxyl group, and a compound (a2122) having two or more polymerizable unsaturated groups and no hydroxyl group.
• Examples of the compound (a2121) having one polymerizable unsaturated group and no hydroxyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, "isostearyl acrylate” (trade name, manufactured by Osaka Organic Chemical Industry Ltd.), cyclohexyl (meth)acrylate, methylcyclohexyl alkyl or cyclo
• the compound (a2121) having one polymerizable unsaturated group and no hydroxyl group can be used as plant-derived raw materials.
• commercially available product names include “NOAA” (n-octyl acrylate, biomass degree 72%), “LA” (lauryl acrylate and dodecyl acrylate, biomass degree 80%), “STA” (stearyl acrylate, biomass degree 85%), “IBXA” (isobornyl acrylate, biomass degree 76%), and “Viscoat #150” (tetrahydrofurfuryl acrylate, biomass degree 62%) (all of which are product names, manufactured by Osaka Organic Chemical Industry Ltd.).
• These compounds (a2121) that have one polymerizable unsaturated group and no hydroxyl group can be used alone or in combination of two or more.
• Examples of the compound (a2122) having two or more polymerizable unsaturated groups and no hydroxyl group include allyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-hexanediol di(meth)acrylate, 1,8-hexanediol di(meth)acrylate, 1,9-hexanediol di(meth)acrylate, 2,2 ...
• acrylates examples include trimethylsilyl di(meth)acrylate, pentaerythritol tetra(meth)acrylate, 1,1,1-trishydroxymethylethane tri(meth)acrylate, 1,1,1-trishydroxymethylpropane tri(meth)acrylate, methylene bis(meth)acrylamide, ethylene bis(meth)acrylamide, triallyl isocyanurate, diallyl terephthalate, divinylbenzene, polyethylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate.
• These compounds (a2122) that have two or more polymerizable unsaturated groups and no hydroxyl group can be used alone or in combination of two or more.
• the compound (a2122) having two or more polymerizable unsaturated groups and no hydroxyl group has the function of imparting a crosslinked structure to the copolymer.
• the content of the compound (a2122) having two or more polymerizable unsaturated groups and no hydroxyl group is preferably within the range of 0.2 to 50 mass%, more preferably within the range of 0.5 to 40 mass%, and even more preferably within the range of 0.7 to 20 mass%, based on the total solid content of the compound (a212) having a polymerizable unsaturated group and no hydroxyl group, from the viewpoints of adhesion of the coating film formed, peelability after peeling heat load, and crack resistance, etc.
• the content of the compound (a212) having a polymerizable unsaturated group and no hydroxyl group is preferably in the range of 50 to 99 mass%, more preferably in the range of 60 to 97 mass%, and even more preferably in the range of 70 to 95 mass%, based on the total solid content of the compound (a21) having a polymerizable unsaturated group and no hydroxyl group or having one hydroxyl group, from the viewpoint of production stability, etc.
• the urethane resin portion ( a1) can be obtained from components including a polyisocyanate component (a11), a polyol component (a12), and, if necessary, a compound having both an active hydrogen group and an ion-forming group as a water-dispersible group-imparting component.
• Polyisocyanate component (a11) examples include alicyclic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates.
• the components of the polyisocyanate component (a11) preferably contain plant-derived raw materials from the viewpoint of the environmental impact of the coating film to be formed. In other words, it is preferable that at least a portion of the polyisocyanate component (a11) is composed of plant-derived raw materials.
• alicyclic polyisocyanates 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, alicyclic diisocyanates such as 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or a mixture thereof, methylenebis(4,1-cyclohexanediyl)diisocyanate (common name: hydrogenated MDI), and norbornane diisocyanate; 1,3,5-triisocyanatocycl
• the aliphatic polyisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4 or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine aliphatic diisocyanates such as 2,6-diisocyanatohexanoate 2-isocyanatoethyl, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diis
• aromatic aliphatic polyisocyanate examples include aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene)diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ⁇ , ⁇ '-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; and aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.
• aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene)diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ⁇ , ⁇ '-diisocyanato-1,4-
• aromatic polyisocyanate examples include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4-TDI) or 2,6-tolylene diisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, etc.; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, etc.; aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate, etc.
• examples of derivatives of the polyisocyanates include dimers, trimers, biurets, allophanates, uretdione, uretoimine, isocyanurates, oxadiazinetriones, polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), crude TDI, etc.
• the above polyisocyanates and their derivatives may be used alone or in combination of two or more kinds.
• the above polyisocyanates may be used in the form of blocked isocyanates blocked with a blocking agent.
• the above blocking agents include, for example, phenol-based agents such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; lactam-based agents such as ⁇ -caprolactam, ⁇ -valerolactam, ⁇ -butyrolactam, and ⁇ -propiolactam; aliphatic alcohol-based agents such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, and lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monoethyl ether.
• phenol-based agents such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonyl
• Ether-based compounds such as ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; alcohol-based compounds such as benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate; formamide oxime, acetamide oxime, acetoxime, methyl ethyl keto oxime, and the like.
• alcohol-based compounds such as benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate,
• Oximes such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, and other active methylenes; mercaptans such as butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol, and other acid amides such as acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetic acid amide, stearic acid amide, and benzamide; cobalt amides such as acetamide, acetanilide, acetotoluide, acrylamide, methacrylamide, acetic acid amide, stearic acid amide, and benzamide; im
• azole compounds examples include pyrazole or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; imidazole or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenylimidazole; and imidazoline derivatives such as 2-methylimidazoline and 2-phenylimidazoline.
• pyrazole or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-
• solvents used in the blocking reaction are preferably those that are not reactive with isocyanate groups, for example, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and solvents such as N-methyl-2-pyrrolidone (NMP).
• NMP N-methyl-2-pyrrolidone
• polyisocyanate component (a11) commercially available products can be used as plant-derived raw materials.
• commercially available products include "STABIO (registered trademark) PDI (registered trademark)” (1,5-pentamethylene diisocyanate, biomass content 71%) (all trade names, manufactured by Mitsui Chemicals, Inc.).
• Polyol component (a12) The polyol component (a12) is a compound having at least two hydroxyl groups in one molecule.
• the components of the polyol component (a12) preferably contain plant-derived raw materials, from the viewpoint of the environmental impact of the coating film formed.
• the polyol component (a12) preferably contains at least one selected from polycarbonate polyol (a121) and polyether polyol (a122), and more preferably contains polycarbonate polyol (a121), from the viewpoints of adhesion and peelability of the coating film to be formed.
• the polycarbonate polyol (a121) is a compound obtained by a conventional method of polycondensation reaction of a known polyol component with a carbonylating agent.
• the polyol component include a diol component and a polyhydric alcohol component such as a trihydric or higher alcohol.
• the diol components include linear diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-ethyl-1,6-hexanediol, 2,2-diethyl-1,3-propanediol, and 2-butyl-2-ethyl-1,3-propanediol.
• linear diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexane
• suitable diols include branched diols such as 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, and 2-ethyl-1,3-hexanediol; alicyclic diols such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; aromatic diols such as p-xylenediol and p-tetrachloroxylenediol; and ether-based diols such as diethylene glycol and dipropylene glycol. These diol components can be used alone or in combination of two or more.
• trihydric or higher alcohols examples include glycerin, trimethylolethane, trimethylolpropane, a dimer of trimethylolpropane, pentaerythritol, etc. These trihydric or higher alcohols can be used alone or in combination of two or more kinds.
• the carbonylating agent may be any known agent. Specific examples include alkylene carbonate, dialkyl carbonate, diallyl carbonate, phosgene, etc., and one or more of these may be used in combination. Among these, preferred examples include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate, etc.
• polycarbonate polyol (a121)
• commercially available products can be used as plant-derived raw materials.
• Commercially available product names include the BENEBiOL (trademark) series (polycarbonate diol), for example, “BENEBiOL HS0830B” (biomass degree 35%), “BENEBiOL HS0840B” (biomass degree 43%), “BENEBiOL HS0840H” (biomass degree 37%), “BENEBiOL HS085OH” (biomass degree 44%), and "BENEBi BENEBiOL NL1010DB (biomass degree 22%), BENEBiOL NL2010DB (biomass degree 21%), BENEBiOL NL3010DB (biomass degree 21%), BENEBiOL NL2030DB (biomass degree 45%), and BENEBiOL NL2000D (biomass degree 92%) (all product names, manufactured by Mitsubishi Chemical Corporation).
• the number average molecular weight of the polycarbonate polyol (a121) is preferably within the range of 500 to 5,000, more preferably within the range of 600 to 4,000, and even more preferably within the range of 700 to 3,000, from the viewpoints of the adhesion, releasability, and releasability after thermal stress of the coating film formed.
• the content of the polycarbonate polyol (a121) is preferably within the range of 35 to 100 mass%, more preferably within the range of 40 to 97 mass%, and even more preferably within the range of 45 to 95 mass%, based on the total solid content of the polyol component (a12), from the viewpoints of adhesion and peelability of the coating film to be formed.
• polyether polyol (a122) an alkylene oxide adduct of a low molecular weight polyol, a ring-opening (co)polymer of an alkylene oxide or a cyclic ether (such as tetrahydrofuran), etc.
• polyether polyol an alkylene oxide adduct of a low molecular weight polyol, a ring-opening (co)polymer of an alkylene oxide or a cyclic ether (such as tetrahydrofuran), etc.
• Specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene glycol-propylene glycol (block or random) copolymers, polyhexamethylene glycol, polyoctamethylene glycol, etc.
• the above polyether polyols can be used alone or in combination of two or more.
• the number average molecular weight of the polyether polyol (a122) is preferably within the range of 500 to 5,000, more preferably within the range of 600 to 4,000, and even more preferably within the range of 1,000 to 2,500, from the viewpoints of the adhesion, releasability, and releasability after thermal stress of the coating film formed.
• the content of the polyether polyol (a122) is preferably within the range of 1.0 to 85 mass%, more preferably within the range of 2.0 to 60 mass%, and even more preferably within the range of 5.0 to 40 mass%, based on the total solid content of the polyol component (a12), from the viewpoints of the adhesion, releasability, and releasability after thermal loading of the coating film to be formed.
• the polyol component (a12) may also contain a compound (a123) having two or more hydroxyl groups and one or more polymerizable unsaturated groups.
• the compound (a123) having two or more hydroxyl groups and one or more polymerizable unsaturated groups imparts a polymerizable unsaturated group to the side chain of the urethane resin portion (a1).
• Examples of the compound (a123) having two or more hydroxyl groups and one or more polymerizable unsaturated groups include a reaction product of a glycidyl group-containing compound with (meth)acrylic acid, a reaction product of a trifunctional or higher polyol with (meth)acrylic acid, etc.
• the content of the compound (a123) having two or more hydroxyl groups and one or more polymerizable unsaturated groups is preferably within the range of 1.0 to 15 mass%, more preferably within the range of 2.0 to 10 mass%, and even more preferably within the range of 3.0 to 8.0 mass%, based on the total solid content of the polyol component (a12), from the viewpoints of adhesion, peelability, peelability after heat load, and crack resistance of the coating film formed.
• the polyol component (a12) may include a polyol component (a124) other than polycarbonate polyol (a121), polyether polyol (a122), or compound (a123) having two or more hydroxyl groups and one or more polymerizable unsaturated groups.
• polyol component (a124) other than the polycarbonate polyol (a121), polyether polyol (a122), and compound (a123) having two or more hydroxyl groups and one or more polymerizable unsaturated groups for example, low molecular weight polyols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexane glycol, 2,5-hexanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, tricyclodecane dimethanol, and 1,4-cyclohexane dimethanol can be used.
• low molecular weight polyols can be used alone or in combination of two or more.
• polystyrene resin other than the polycarbonate polyol (a121), polyether polyol (a122), and compound having two or more hydroxyl groups and one or more polymerizable unsaturated groups (a123), high molecular weight polyols such as polyester polyols and polyether ester polyols can be used. These high molecular weight polyols can be used alone or in combination of two or more.
• the polyester polyols include those obtained by polycondensing dicarboxylic acids (anhydrides) such as adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, and phthalic acid with low molecular weight polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octamethylenediol, and neopentyl glycol under conditions of excess hydroxyl groups.
• dicarboxylic acids anhydrides
• polyester polyols obtained by ring-opening polymerization of lactones using glycol as an initiator.
• These polyester polyols can be used alone or in combination of two or more.
• the polyether ester polyols include those obtained by adding an ether group-containing polyol (such as the polyether polyol (a122) or diethylene glycol) or a mixture of this with other glycols to a dicarboxylic acid (anhydride) such as those exemplified for the polyester polyols above, and reacting it with an alkylene oxide, such as polytetramethylene glycol-adipic acid condensate.
• ether group-containing polyol such as the polyether polyol (a122) or diethylene glycol
• anhydride such as those exemplified for the polyester polyols above
• an alkylene oxide such as polytetramethylene glycol-adipic acid condensate.
• Examples of the compounds having both active hydrogen groups and ion-forming groups include compounds having two or more hydroxyl groups and one or more carboxyl groups in one molecule, compounds having two or more hydroxyl groups and one or more sulfonic acid groups in one molecule, and compounds having two or more amino groups and one or more carboxyl groups in one molecule. These can be used alone or in combination of two or more kinds.
• compounds having both the above-mentioned active hydrogen group and ion-forming group can be preferably used that have two or more hydroxyl groups and one or more carboxyl groups in one molecule, and compounds that have two or more hydroxyl groups and one or more sulfonic acid groups in one molecule.
• compounds having both two or more hydroxyl groups and an ion-forming group such as the above-mentioned compounds having two or more hydroxyl groups and one or more carboxyl groups in one molecule, and compounds having two or more hydroxyl groups and one or more sulfonic acid groups in one molecule, are considered to be included in the polyol component (a12).
• Examples of the above-mentioned compounds having two or more hydroxyl groups and one or more carboxyl groups in one molecule include alkanol carboxylic acid compounds such as dimethylolpropionic acid, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolheptanoic acid, dimethylolnonanoic acid, 1-carboxy-1,5-pentylenediamine, dihydroxybenzoic acid, and 3,5-diaminobenzoic acid, and half ester compounds of polyoxypropylenetriol with maleic anhydride and/or phthalic anhydride.
• alkanol carboxylic acid compounds such as dimethylolpropionic acid, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolheptanoic acid, dimethylolnonanoic acid, 1-carboxy-1,5-pentylenediamine, dihydroxybenzoic acid, and 3,5-diaminobenzoic acid, and half
• Examples of the compound having two or more hydroxyl groups and one or more sulfonic acid groups in one molecule include 2-sulfonic acid-1,4-butanediol, 5-sulfonic acid-di- ⁇ -hydroxyethyl isophthalate, and N,N-bis(2-hydroxyethyl)aminoethylsulfonic acid.
• the compound having both the above-mentioned active hydrogen group and ion-forming group it is preferable to use a compound having two or more hydroxyl groups and one or more carboxyl groups in one molecule, from the viewpoint of the flexibility of the coating film that is formed.
• the content is preferably within the range of 1 to 30 mass%, more preferably within the range of 1 to 25 mass%, and even more preferably within the range of 1 to 20 mass%, based on the total amount of the compounds constituting the polyol component (a12), from the viewpoint of the production stability of the acrylic urethane composite resin (A).
• the method for producing the urethane resin portion (a1) is not particularly limited, and a conventionally known method can be applied.
• the production method is to synthesize the urethane resin portion (a1) by subjecting the polyisocyanate component (a11) and the polyol component (a12) to a urethane reaction in an organic solvent, or by further adding a compound having both an active hydrogen group and an ion-forming group to the isocyanate component (a11) and the polyol component (a12) as necessary to a urethane reaction.
• the urethane resin portion (a1) preferably contains a compound having both the active hydrogen group and an ion-forming group, from the viewpoint of the production stability of the acrylic urethane composite resin (A).
• a polymerization inhibitor can also be added.
• a catalyst can be used, if necessary, in the urethane reaction of the polyisocyanate component (a11) and the polyol component (a12).
• the catalyst examples include bismuth carboxylate compounds such as tris(2-ethylhexanoate)bismuth(III); organotin compounds such as dibutyltin dilaurate, dibutyltin dioctoate, and stannous octoate; and tertiary amine compounds such as triethylamine and triethylenediamine.
• bismuth carboxylate compounds such as tris(2-ethylhexanoate)bismuth(III)
• organotin compounds such as dibutyltin dilaurate, dibutyltin dioctoate, and stannous octoate
• tertiary amine compounds such as triethylamine and triethylenediamine.
• the urethane reaction is preferably carried out at 50 to 120°C.
• an organic solvent that is inactive to isocyanates and does not interfere with the urethane reaction can be used.
• organic solvents include aromatic hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, and ketone solvents such as acetone and methyl ethyl ketone.
• aromatic hydrocarbon solvents such as toluene and xylene
• ester solvents such as ethyl acetate and butyl acetate
• ketone solvents such as acetone and methyl ethyl ketone.
• ketone solvents and ester solvents are preferably used from the viewpoint of water dispersion stability, etc.
• organic solvents can be used alone or in combination of two or more.
• the compound (a21) having the polymerizable unsaturated group and no hydroxyl group or having one hydroxyl group can be used instead of a solvent.
• a solvent it is preferable to use the compound (a212) having the polymerizable unsaturated group and no hydroxyl group.
• polymerization inhibitor for example, known polymerization inhibitors such as di-t-butylhydroxytoluene, methoxyphenol, and other phenolic hydroxyl group-containing compounds, benzoquinone, and other carbonyl group-containing aromatic compounds, nitroso skeleton-containing compounds, and N-oxyl skeleton-containing compounds can be used.
• the content ratio of the polyisocyanate component (a11) and the polyol component (a12) in the urethane resin portion (a1) is preferably within a range of 1/1.01 to 1/3.0, and more preferably within a range of 1/1.05 to 1/2.0, in terms of the molar ratio of active hydrogen groups in the polyol component (a12) to isocyanate groups in the polyisocyanate component (a11).
• the number average molecular weight of the urethane resin portion (a1) is preferably within the range of 1,000 to 20,000, more preferably within the range of 2,000 to 15,000, and even more preferably within the range of 2,500 to 10,000, from the viewpoint of the manufacturing stability of the acrylic urethane composite resin (A).
• the average molecular weight is a value calculated based on the molecular weight of standard polystyrene from a chromatogram measured by gel permeation chromatography.
• the gel permeation chromatograph used was an "HLC8120GPC” (manufactured by Tosoh Corporation). Four columns were used: “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, and "TSKgel G-2000HXL” (all product names manufactured by Tosoh Corporation). The conditions were as follows: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 mL/min, detector: RI.
• a neutralizing agent for the ion-forming groups may be added, if necessary.
• the neutralizing agent is not particularly limited as long as it can neutralize the ion-forming groups.
• Examples of basic compounds for neutralization include organic amines such as ammonia, diethylamine, ethylethanolamine, diethanolamine, triethanolamine, monoethanolamine, monopropanolamine, isopropanolamine, ethylaminoethylamine, hydroxyethylamine, triethylamine, tributylamine, dimethylethanolamine, diethylenetriamine, N-methylmorpholine, and N-ethylmorpholine; or alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.
• These neutralizing agents can be used alone or in combination of two or more.
• the amount of neutralizing agent added is preferably 0.1 to 1.5 equivalents relative to the acid group such as a carboxyl group, and more preferably 0.3 to 1.2 equivalents.
• An emulsifier such as a surfactant can also be used to improve the water dispersion stability of the acrylic urethane composite resin (A).
• anionic surfactants As the emulsifier, well-known anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, polymeric surfactants, reactive surfactants, etc. can be used. When using these, anionic surfactants, nonionic surfactants, or cationic surfactants are preferred because they are low in cost and provide good emulsification.
• anionic surfactants include alkyl sulfates such as sodium dodecyl sulfate, potassium dodecyl sulfate, and ammonium dodecyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulforicinolate; alkyl sulfonates such as alkali metal salts of sulfonated paraffin and ammonium salts of sulfonated paraffin; fatty acid salts such as sodium laurate, triethanolamine oleate, and triethanolamine abietate; alkylaryl sulfonates such as sodium benzenesulfonate and alkali metal sulfates of alkali phenol hydroxyethylene; high alkyl naphthalene sulfonates; naphthalene sulfonate-formaldehyde condensates; dialkyl sulfosuccinates; polyoxyethylene
• nonionic surfactant examples include ethylene oxide and/or propylene oxide adducts of alcohols having 1 to 18 carbon atoms, ethylene oxide and/or propylene oxide adducts of alkylphenols, ethylene oxide and/or propylene oxide adducts of alkylene glycols and/or alkylenediamines, etc.
• the alcohols 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, tertiary amyl alcohol, hexanol, octanol, decane alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, etc.
• the alkylphenols include phenol, methylphenol, 2,4-di-tertiary butylphenol, 2,5-di-tertiary butylphenol, 3,5-di-tertiary butylphenol, 4-(1,3-tetramethylbutyl)phenol, 4-isooctylphenol, 4-nonylphenol, 4-tertiary octylphenol, 4-dodecyl phenol, 4-oct ...
• 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, and 1,6-hexanediol.
• alkylene diamine examples include those in which the alcoholic hydroxyl group of these alkylene glycols is replaced with an amino group.
• the ethylene oxide and propylene oxide adducts may be random adducts or block adducts.
• cationic surfactant examples include primary to tertiary amine salts, pyridinium salts, alkyl pyridinium salts, and quaternary ammonium salts such as alkyl halide quaternary ammonium salts.
• surfactants can be used alone or in combination of two or more.
• dispersion using a normal stirrer is possible, but to obtain a uniform aqueous dispersion with finer particle sizes, a homomixer, homogenizer, disperser, line mixer, etc. can be used.
• a chain extender other than water may be added as necessary to react the urethane resin portion (a1) with the chain extender.
• a known chain extender having active hydrogen may be used. Specific examples include diamine compounds such as ethylenediamine, hexamethylenediamine, cyclohexanediamine, cyclohexylmethanediamine, and isophoronediamine, triamine compounds such as diethylenetriamine, tetraamine compounds such as triethylenetetraamine, aminoalcohol compounds such as hydroxyethylhydrazine, hydroxyethyldiethylenetriamine, N-(2-aminoethyl)ethanol, 1,3-diamino-2-propanol, and 3-aminopropanediol, and hydrazine.
• a diamine compound such as ethylenediamine can be preferably used from the viewpoint of peelability and crack resistance of the coating film formed after thermal stress.
• an amino alcohol compound such as N-(2-aminoethyl)ethanol can be used for the purpose of introducing reactive functional groups into the acrylic urethane composite resin (A).
• the above-mentioned polymerization initiators include, for example, organic peroxides such as benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, tert-butyl peroxy laurate, tert-butyl peroxy isopropyl carbonate, tert-butyl peroxy acetate, and diisopropylbenzene hydroperoxide; azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile), azobis(2-methyl
• the polymerization initiator include azo compounds such as 4,4'-azobis(4-cyanobutanoic acid), dimethylazobis(2-methylpropionate), azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], azobis ⁇ 2-methyl-N-[2-(1-hydroxybutyl)
• polymerization initiators can be used alone or in combination of two or more.
• the polymerization initiators can be used in combination with reducing agents such as sugars, sodium formaldehyde sulfoxylate, and iron complexes, as necessary, to form redox initiators.
• the amount of the polymerization initiator used is generally preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, based on the total amount of all monomers used.
• the method of adding the polymerization initiator is not particularly limited and can be appropriately selected depending on the type and amount.
• the polymerization initiator can be contained in the monomer mixture or aqueous medium in advance, or can be added all at once during polymerization, or can be added dropwise.
• the polymerization reaction can be carried out by a conventional method, such as emulsion polymerization in water or self-emulsification.
• the acrylic urethane composite resin (A) synthesized in the above manufacturing steps 1 to 3 is synthesized as a dispersion in an aqueous solvent and is considered to have a particulate form.
• an aqueous solvent refers to a solvent whose main component is water (for example, a solvent in which 70 to 100% by mass of the solvent is water).
• the average particle size of the acrylic urethane composite resin (A) is preferably within the range of 10 to 5000 nm, more preferably within the range of 10 to 1000 nm, particularly preferably within the range of 20 to 500 nm, and even more particularly preferably within the range of 50 to 140 nm, from the viewpoint of the adhesion, peelability, and cracking resistance of the coating film formed.
• the average particle size of the acrylic urethane composite resin (A) can be adjusted to the desired average particle size by adjusting particle size control factors such as the composition of the raw materials (polyisocyanate component, polyol component, amine component, etc.), the type and amount of emulsifier, the emulsifier charge ratio, the type and amount of neutralizing agent, etc.
• the average particle size of the acrylic urethane composite resin (A) is a value measured at 20°C using a particle size distribution measuring device that uses dynamic light scattering, after diluting with deionized water in a conventional manner.
• a particle size distribution measuring device that uses dynamic light scattering, after diluting with deionized water in a conventional manner.
• the "ELSZ-2000" product name, manufactured by Otsuka Electronics Co., Ltd.
• the hydroxyl value of the urethane resin portion (a1) is preferably within the range of 0 to 45 mgKOH/g, more preferably within the range of 0 to 30 mgKOH/g, and even more preferably within the range of 0 to 25 mgKOH/g, from the viewpoint of the adhesion and releasability of the coating film formed.
• the acid value of the urethane resin portion (a1) is preferably within the range of 3.0 to 75 mgKOH/g, more preferably within the range of 10 to 60 mgKOH/g, and even more preferably within the range of 20 to 40 mgKOH/g, from the viewpoint of the manufacturing stability of the acrylic urethane composite resin (A).
• the hydroxyl value of the acrylic resin portion (a2) is preferably within the range of 0 to 90 mgKOH/g, more preferably within the range of 0 to 65 mgKOH/g, and even more preferably within the range of 0 to 45 mgKOH/g, from the viewpoint of the adhesion and peelability of the coating film to be formed.
• the acid value of the acrylic resin portion (a2) is preferably within the range of 0.7 to 80 mgKOH/g, more preferably within the range of 3.5 to 40 mgKOH/g, and even more preferably within the range of 7.5 to 25 mgKOH/g.
• the hydroxyl value of the acrylic urethane composite resin (A) is preferably within the range of 0 to 100 mgKOH/g, more preferably within the range of 0 to 50 mgKOH/g, and even more preferably within the range of 0 to 10 mgKOH/g, from the viewpoint of the adhesion and peelability of the coating film formed.
• the acid value of the acrylic urethane composite resin (A) is preferably within the range of 5 to 40 mgKOH/g, more preferably within the range of 5 to 30 mgKOH/g, and even more preferably within the range of 7 to 30 mgKOH/g, from the viewpoint of the manufacturing stability of the acrylic urethane composite resin (A).
• the mass ratio (a2)/(a1) of the acrylic resin portion (a2) and the urethane resin portion (a1) in the acrylic urethane composite resin (A) is preferably within the range of 20/80 to 80/20, more preferably within the range of 30/70 to 70/30, and particularly preferably within the range of 40/60 to 60/40, from the viewpoint of the adhesion and peelability of the coating film to be formed.
• the solids concentration in the aqueous dispersion of the acrylic urethane composite resin (A) is preferably in the range of 20 to 50% by mass, and more preferably in the range of 30 to 50% by mass. If the solids concentration is 50% by mass or less, emulsification is easy and the aqueous dispersion can be easily obtained. If the solids concentration is 20% by mass or more, the solvent component is reduced, and the solids concentration of the peelable aqueous automotive paint composition can be increased.
• solid content refers to non-volatile components such as resins, hardeners, and pigments that remain after drying at 110°C for 1 hour.
• the solid content can be determined, for example, by weighing a sample into a heat-resistant container such as an aluminum foil cup, spreading the sample on the bottom of the container, drying at 110°C for 1 hour, and weighing the mass of the components remaining after drying.
• solid content concentration means the mass ratio of the above solid content in the composition. Therefore, the solid content concentration of the composition can be calculated, for example, by weighing out 1.0 g of the composition into a heat-resistant container such as an aluminum foil cup, spreading the composition on the bottom of the container, drying at 110°C for 1 hour, weighing the mass of the components in the composition remaining after drying, and determining the ratio of the mass of the components remaining after drying to the total mass of the composition before drying.
• the content of the acrylic urethane composite resin (A) in the peelable aqueous coating composition for automobiles of the present invention is preferably within the range of 15 to 95 mass %, more preferably within the range of 30 to 85 mass %, and even more preferably within the range of 40 to 75 mass %, based on the resin solid content in the peelable aqueous coating composition for automobiles, from the viewpoints of adhesion, peelability, and peelability after thermal loading of the coating film formed.
• the peelable aqueous automotive coating composition of the present invention preferably contains an acrylic resin (B) from the viewpoint of the peelability of the coating film formed after thermal loading.
• the acrylic resin (B) a water-soluble or water-dispersible acrylic resin that has been conventionally used in water-based paints can be used. Unlike the acrylic urethane composite resin (A), the acrylic resin (B) does not contain a urethane resin portion (a1).
• the acrylic resin (B) can be produced, for example, by copolymerizing a polymerizable unsaturated monomer by a method known per se, such as a solution polymerization method in an organic solvent or an emulsion polymerization method in water.
• Alkyl or cycloalkyl (meth)acrylates for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl
• Carboxyl group-containing polymerizable unsaturated monomers (meth)acrylic acid, maleic acid, crotonic acid, ⁇ -carboxyethyl (meth)acrylate, and the like.
• Nitrogen-containing polymerizable unsaturated monomers (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, and adducts of glycidyl (meth)acrylate and amine compounds.
• (xii) Polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule: allyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, etc.
• Epoxy group-containing polymerizable unsaturated monomers 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) Polymerizable unsaturated monomers having a sulfonic acid group: 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth)acrylate, allylsulfonic acid, 4-styrenesulfonic acid, and the like; sodium salts and ammonium salts of these sulfonic acids.
• (xvii) Polymerizable unsaturated monomers having an ultraviolet absorbing functional group: 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, and the like.
• Light-stable polymerizable unsaturated monomers 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and the like.
• (xix) Polymerizable unsaturated monomers having a carbonyl group: acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone), and the like.
• (xx) Polymerizable unsaturated monomers having an acid anhydride group: maleic anhydride, itaconic anhydride, citraconic anhydride, etc.
• (xxi) Hydroxyl-containing polymerizable unsaturated monomers monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ⁇ -caprolactone-modified products of the monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms; N-hydroxymethyl (meth)acrylamide; allyl alcohol; and (meth)acrylates having a polyoxyethylene chain whose molecular terminal is a hydroxyl group.
• monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth
• the proportion of the hydroxyl group-containing polymerizable unsaturated monomer used is preferably within the range of 1 to 50 mass%, more preferably within the range of 2 to 40 mass%, and even more preferably within the range of 3 to 30 mass%, based on the total amount of the monomer components.
• the proportion of the carboxyl group-containing polymerizable unsaturated monomer used is preferably within the range of 1 to 50 mass%, more preferably within the range of 1.5 to 40 mass%, and even more preferably within the range of 2 to 30 mass%, based on the total amount of the monomer components constituting the acrylic resin (B).
• the constituent components of the acrylic resin (B) contain a polymerizable unsaturated monomer having two or more of the above-mentioned polymerizable unsaturated groups in one molecule.
• the proportion of the polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule is preferably within the range of 0.1 to 10 mass%, more preferably within the range of 0.2 to 5 mass%, and even more preferably within the range of 0.5 to 3 mass%, based on the total amount of the monomer components constituting the acrylic resin (B), from the viewpoints of adhesion, peelability, peelability after heat load, and crack resistance of the coating film formed.
• the hydroxyl value of the acrylic resin (B) is preferably within the range of 1 to 200 mgKOH/g, more preferably within the range of 2 to 180 mgKOH/g, and even more preferably within the range of 5 to 150 mgKOH/g.
• the acid value of the acrylic resin (B) is preferably within the range of 1 to 75 mgKOH/g, more preferably within the range of 5 to 50 mgKOH/g, and even more preferably within the range of 5 to 40 mgKOH/g.
• the content of the acrylic resin (B) is preferably within the range of 5 to 80 mass %, more preferably within the range of 10 to 70 mass %, and even more preferably within the range of 20 to 60 mass %, based on the resin solid content in the peelable aqueous coating composition for automobiles, from the viewpoints of adhesion, removability, and removability after thermal loading of the coating film to be formed.
• the peelable aqueous coating composition for automobiles of the present invention preferably contains an oligomer (C) having a weight average molecular weight in the range of 200 to 2,000.
• the weight average molecular weight of the oligomer (C) is preferably within the range of 250 to 1800, more preferably within the range of 300 to 1600, and even more preferably within the range of 350 to 1500, from the viewpoint of the adhesion of the coating film to be formed, etc.
• the oligomer (C) preferably contains a diester compound (C1) from the viewpoint of crack resistance of the coating film formed.
• Diester compound (C1) The diester compound (C1) is a diester compound represented by formula (1).
• R 1 and R 2 each independently represent a hydrocarbon group having 4 to 18 carbon atoms
• R 3 represents an alkylene group having 2 to 4 carbon atoms
• m represents an integer of 3 to 20, and the m R 3s may be the same or different from each other.
• the hydrocarbon group represented by R1 or R2 is preferably an alkyl group having 5 to 11 carbon atoms, more preferably an alkyl group having 5 to 9 carbon atoms, and even more preferably an alkyl group having 6 to 8 carbon atoms, from the viewpoint of the cracking resistance of the coating film to be formed.
• R3 is preferably an ethylene group, and m is more preferably an integer of 4 to 10.
• the diester compound (C1) can be obtained, for example, by an esterification reaction between a polyoxyalkylene glycol having two terminal hydroxyl groups and a monocarboxylic acid having a hydrocarbon group having 4 to 18 carbon atoms.
• polyoxyalkylene glycols examples include polyethylene glycol, polypropylene glycol, block copolymers of polyethylene glycol and polypropylene glycol, polybutylene glycol, etc., and among these, it is particularly preferable to use polyethylene glycol.
• examples of monocarboxylic acids having a hydrocarbon group having 4 to 18 carbon atoms include pentanoic acid, hexanoic acid, 2-ethylbutanoic acid, 3-methylpentanoic acid, benzoic acid, cyclohexanecarboxylic acid, heptanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, octanoic acid, 2-ethylhexanoic acid, 4-ethylhexanoic acid, nonanoic acid, 2-ethylheptanoic acid, decanoic acid, 2-ethyloctanoic acid, 4-ethyloctanoic acid, dodecanoic acid, hexadecanoic acid, and octadecanoic acid.
• monocarboxylic acids having an alkyl group with 5 to 9 carbon atoms such as hexanoic acid, heptanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, octanoic acid, 2-ethylhexanoic acid, 4-ethylhexanoic acid, nonanoic acid, 2-ethylheptanoic acid, decanoic acid, 2-ethyloctanoic acid, and 4-ethyloctanoic acid, are preferred, and monocarboxylic acids having an alkyl group with 6 to 8 carbon atoms, such as heptanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, octanoic acid, 2-ethylhexanoic acid, 4-ethylhexanoic acid, nonanoic acid, and 2-ethylheptanoi
• the diesterification reaction between the polyoxyalkylene glycol and the monocarboxylic acid can be carried out by a known method.
• the polyoxyalkylene glycol and the monocarboxylic acid can be used alone or in combination of two or more kinds.
• the weight average molecular weight of the resulting diester compound (C1) is preferably in the range of 320 to 1,000, more preferably in the range of 400 to 800, and particularly preferably in the range of 500 to 700.
• the content of the diester compound (C1) is preferably within the range of 50 to 100 mass %, more preferably within the range of 60 to 100 mass %, and even more preferably within the range of 70 to 100 mass %, based on the total solid content of the oligomer (C), from the viewpoints of adhesion and crack resistance of the coating film formed.
• the oligomer (C) may include an oligomer (C2) other than the diester compound (C1).
• Specific examples include polyoxyalkylene glycols such as polyoxyethylene glycol, polyoxypropylene glycol, and polyoxytetramethylene glycol, as well as etherified products thereof.
• oligomer (C2) other than the diester compound (C1) commercially available products can be used.
• commercially available product names include "Sannix GP250", “Sannix GP400", “Sannix GP600”, and “Sannix GP100” (all of which are product names, manufactured by Sanyo Chemical Industries, Ltd., polyoxypropylene glyceryl ether), “Sannix PP200”, “Sannix PP400", and “Sannix PP1000” (all of which are product names, manufactured by Sanyo Chemical Industries, Ltd., polyoxypropylene glycol), "PTMG250", “PTMG650”, “PTMG1000”, and “PTMG2000” (all of which are product names, manufactured by Mitsubishi Chemical Corporation, polyoxytetramethylene glycol).
• the content of the oligomer (C2) other than the diester compound (C1) is preferably within the range of 0.5 to 30 mass %, more preferably within the range of 1.0 to 20 mass %, and even more preferably within the range of 2.0 to 10 mass %, based on the total solid content of the oligomer (C), from the viewpoints of adhesion and crack resistance of the coating film formed.
• the content of the oligomer (C) is preferably within the range of 0.5 to 50 mass %, more preferably within the range of 1.0 to 40 mass %, and even more preferably within the range of 2.0 to 30 mass %, based on the resin solid content in the peelable automotive water-based paint composition and the total solid content in the peelable automotive water-based paint composition, from the viewpoints of adhesion and crack resistance of the coating film formed.
• the peelable aqueous automotive coating composition of the present invention may further contain, as necessary, resins other than the acrylic urethane composite resin (A) and the acrylic resin (B), curing agents, pigments, organic solvents, curing catalysts, dispersants, anti-settling agents, defoamers, thickeners, UV absorbers, light stabilizers, surface conditioners, etc.
• resins other than the acrylic urethane composite resin (A) and the acrylic resin (B) may further contain, as necessary, resins other than the acrylic urethane composite resin (A) and the acrylic resin (B), curing agents, pigments, organic solvents, curing catalysts, dispersants, anti-settling agents, defoamers, thickeners, UV absorbers, light stabilizers, surface conditioners, etc.
• resins other than the acrylic urethane composite resin (A) and the acrylic resin (B) include acrylic urethane composite resins other than the acrylic urethane composite resin (A), polyester resins, polyurethane resins, polyolefin resins, epoxy resins, etc.
• polyester resin a water-soluble or water-dispersible polyester resin that has been conventionally used in water-based paints and is known per se can be used.
• Polyester resins can usually be produced by an esterification reaction or transesterification reaction between an acid component and an alcohol component.
• acid component compounds that are commonly used as acid components in the production of polyester resins can be used.
• acid components include aliphatic polybasic acids, alicyclic polybasic acids, and aromatic polybasic acids.
• the above-mentioned aliphatic polybasic acids are generally aliphatic compounds having two or more carboxyl groups in one molecule, acid anhydrides of the aliphatic compounds, and esters of the aliphatic compounds.
• the aliphatic polybasic acids include aliphatic polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, octadecanedioic acid, citric acid, and butanetetracarboxylic acid; anhydrides of the aliphatic polybasic acids; and esters of the aliphatic polybasic acids with lower alkyls having about 1 to 4 carbon atoms.
• the above-mentioned aliphatic polybasic acids can be used alone or in combination of two or more kinds.
• the alicyclic polybasic acids are generally compounds having one or more alicyclic structures and two or more carboxyl groups in one molecule, acid anhydrides of the compounds, and esters of the compounds.
• the alicyclic structures are mainly 4- to 6-membered ring structures.
• alicyclic polybasic acids examples include alicyclic polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, and 1,3,5-cyclohexanetricarboxylic acid; anhydrides of the alicyclic polybasic acids; and esters of the alicyclic polybasic acids with lower alkyls having about 1 to 4 carbon atoms.
• the alicyclic polybasic acids can be used alone or in combination of two or more.
• the aromatic polybasic acids are generally aromatic compounds having two or more carboxyl groups in one molecule, acid anhydrides of the aromatic compounds, and esters of the aromatic compounds, such as aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, trimellitic acid, and pyromellitic acid; anhydrides of the aromatic polycarboxylic acids; and esters of the aromatic polycarboxylic acids with lower alkyls having about 1 to 4 carbon atoms.
• the aromatic polybasic acids can be used alone or in combination of two or more kinds.
• aromatic polybasic acid it is preferable to use phthalic acid, phthalic anhydride, isophthalic acid, trimellitic acid, or trimellitic anhydride.
• acid components other than the above-mentioned aliphatic polybasic acids, alicyclic polybasic acids, and aromatic polybasic acids can also be used.
• Such acid components are not particularly limited, and examples thereof include fatty acids such as coconut oil fatty acid, cottonseed oil fatty acid, hempseed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor oil fatty acid, and safflower oil fatty acid; monocarboxylic acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexanoic acid, and 10-phenyloctadecanoic acid;
• a polyhydric alcohol having two or more hydroxyl groups in one molecule can be suitably used.
• the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-pentanediol, 1,7-pentanediol, 1,8-pentanediol, 1,9-pentanediol, 2,10-pentanediol, 2,11-
• Alcohol components other than the above polyhydric alcohols can also be used.
• examples of such alcohol components include, but are not limited to, monoalcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, stearyl alcohol, and 2-phenoxyethanol; and alcohol compounds obtained by reacting monoepoxy compounds such as propylene oxide, butylene oxide, and "Cardura E10P" (trade name, manufactured by HEXION, glycidyl ester of synthetic highly branched saturated fatty acid) with an acid.
• the method for producing the polyester resin is not particularly limited, and can be carried out according to a conventional method.
• the polyester resin can be produced by heating the acid component and the alcohol component in a nitrogen stream at about 150 to 250°C for about 5 to 10 hours, and carrying out an esterification reaction or transesterification reaction between the acid component and the alcohol component.
• the acid component and alcohol component When the acid component and alcohol component are subjected to an esterification reaction or an ester exchange reaction, they may be added to a reaction vessel all at once, or one or both may be added in several portions.
• a hydroxyl group-containing polyester resin may be first synthesized, and then the resulting hydroxyl group-containing polyester resin may be reacted with an acid anhydride to perform half esterification to produce a carboxyl group-containing polyester resin.
• a carboxyl group-containing polyester resin may be first synthesized, and then the alcohol component may be added to produce a hydroxyl group-containing polyester resin.
• a catalyst known per se such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, or tetraisopropyl titanate, can be used as a catalyst to promote the reaction.
• the polyester resin can be modified with fatty acids, monoepoxy compounds, polyisocyanate compounds, acrylic resins, etc. during or after preparation of the resin.
• fatty acids examples include coconut oil fatty acids, cottonseed oil fatty acids, hemp seed oil fatty acids, rice bran oil fatty acids, fish oil fatty acids, tall oil fatty acids, soybean oil fatty acids, linseed oil fatty acids, tung oil fatty acids, rapeseed oil fatty acids, castor oil fatty acids, dehydrated castor oil fatty acids, safflower oil fatty acids, etc.
• monoepoxy compound that can be suitably used is "Cardura E10P" (trade name, manufactured by HEXION, glycidyl ester of synthetic highly branched saturated fatty acid).
• the above polyisocyanate compounds include, for example, aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,3-(isocyanatomethyl)cyclohexane.
• aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate
• hydrogenated xylylene diisocyanate isophorone diisocyanate
• methylcyclohexane-2,4-diisocyanate methylcyclohex
• suitable polyisocyanates include alicyclic diisocyanate compounds; aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate; organic polyisocyanates themselves, such as trivalent or higher polyisocyanates such as lysine triisocyanate; adducts of these organic polyisocyanates with polyhydric alcohols, low molecular weight polyester resins, water, and the like; cyclic polymers of these organic polyisocyanates (e.g., isocyanurates), biuret-type adducts, and the like. These polyisocyanate compounds can be used alone or in combination of two or more.
• the polyester resin can be modified with an acrylic resin by known methods, such as a method of polymerizing a mixture of a polyester resin containing a polymerizable unsaturated group and a polymerizable unsaturated monomer, or a method of reacting a polyester resin with an acrylic resin.
• the content of the polyester resin is preferably within the range of 2 to 70 mass %, more preferably within the range of 5 to 50 mass %, and even more preferably within the range of 10 to 40 mass %, based on the resin solid content in the peelable automotive water-based paint composition.
• the curing agent is a compound that can react with the crosslinkable functional groups in the acrylic urethane composite resin (A) and the acrylic resin (B) to cure the peelable aqueous coating composition for automobiles.
• the curing agent can be used alone or in combination of two or more kinds.
• the peelable aqueous automotive paint composition of the present invention preferably does not contain the above-mentioned curing agent, from the viewpoint of the peelability of the coating film formed, etc.
• curing agents include polyisocyanate compounds, blocked polyisocyanate compounds, polycarbodiimide compounds, amino resins, epoxy group-containing compounds, carboxyl group-containing compounds, hydrazide group-containing compounds, and semicarbazide group-containing compounds.
• the polyisocyanate compound is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates.
• the polyisocyanate compound may be a prepolymer obtained by reacting the polyisocyanate or its derivative with a compound that can react with the polyisocyanate under conditions of excess isocyanate groups.
• the compound that can react with the polyisocyanate include compounds having active hydrogen groups such as hydroxyl groups and amino groups.
• Specific examples of compounds that can be used include polyhydric alcohols, low molecular weight polyester resins, amines, water, etc.
• the content of the polyisocyanate compound is preferably within the range of 1 to 80 mass %, more preferably within the range of 5 to 70 mass %, and even more preferably within the range of 10 to 65 mass %, based on the total solid content of the curing agent, from the viewpoints of the adhesion, releasability, and releasability after thermal stress of the coating film formed.
• the polyisocyanate compound may be a polymer of an isocyanate group-containing polymerizable unsaturated monomer, or a copolymer of the isocyanate group-containing polymerizable unsaturated monomer and a polymerizable unsaturated monomer other than the isocyanate group-containing polymerizable unsaturated monomer.
• the blocked polyisocyanate compound is a compound in which the isocyanate groups of the polyisocyanate compound are blocked with a blocking agent.
• Solvents used in blocking reactions should be those that are not reactive with isocyanate groups, for example, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and N-methyl-2-pyrrolidone (NMP).
• ketones such as acetone and methyl ethyl ketone
• esters such as ethyl acetate
• NMP N-methyl-2-pyrrolidone
• a hydroxycarboxylic acid having one or more hydroxyl groups and one or more carboxyl groups such as hydroxypivalic acid or dimethylolpropionic acid
• a blocked polyisocyanate compound in which an isocyanate group is blocked with the above-mentioned hydroxycarboxylic acid and then the carboxyl group of the hydroxycarboxylic acid is neutralized to impart water dispersibility can be preferably used.
• the content of the blocked polyisocyanate compound is preferably within the range of 1 to 80 mass%, more preferably within the range of 5 to 70 mass%, and even more preferably within the range of 10 to 65 mass%, based on the total solid content of the curing agent, from the viewpoints of adhesion, releasability, and releasability after thermal loading of the coating film formed.
• the above curing agents can be used alone or in combination of two or more.
• the polycarbodiimide compound is a compound that has at least two carbodiimide groups in one molecule, and can be, for example, a compound that is produced by subjecting the isocyanate groups of an isocyanate group-containing compound to a carbon dioxide-removal reaction.
• polycarbodiimide compound it is preferable to use a water-soluble or water-dispersible polycarbodiimide compound.
• a water-soluble or water-dispersible polycarbodiimide compound any polycarbodiimide compound that can be stably dissolved or dispersed in an aqueous medium can be used without any particular restrictions.
• water-dispersible polycarbodiimide compound that can be used include “Carbodilite E-01,” “Carbodilite E-02,” and “Carbodilite E-05” (all of which are product names manufactured by Nisshinbo Chemical Inc.).
• the content of the polycarbodiimide compound is preferably within the range of 1 to 80 mass %, more preferably within the range of 5 to 70 mass %, and even more preferably within the range of 10 to 65 mass %, based on the total solid content of the curing agent, from the viewpoints of the adhesion, releasability, and releasability after thermal loading of the coating film to be formed.
• amino resin a partially methylolated amino resin or a fully methylolated amino resin obtained by the reaction of an amino component with an aldehyde component can be used.
• amino component include melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide.
• aldehyde component include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.
• methylol groups of the above methylolated amino resins may be partially or completely etherified with a suitable alcohol.
• suitable alcohols used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethyl-1-butanol, and 2-ethyl-1-hexanol.
• melamine resin is preferred.
• methyl etherified melamine resin in which the methylol groups of partially or fully methylolated melamine resin are partially or completely etherified with methyl alcohol butyl etherified melamine resin in which the methylol groups of partially or fully methylolated melamine resin are partially or completely etherified with butyl alcohol
• methyl-butyl mixed etherified melamine resin in which the methylol groups of partially or fully methylolated melamine resin are partially or completely etherified with methyl alcohol and butyl alcohol are preferred, with methyl-butyl mixed etherified melamine resin being more preferred.
• the weight average molecular weight of the melamine resin is preferably 400 to 6,000, more preferably 500 to 4,000, and even more preferably 600 to 3,000.
• the peelable aqueous coating composition for automobiles of the present invention contains the above-mentioned melamine resin
• the peelable aqueous coating composition for automobiles can contain, as a curing catalyst, a sulfonic acid such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, etc.; a neutral salt of such a sulfonic acid with an amine; a neutral salt of a phosphoric acid ester compound with an amine, etc.
• a sulfonic acid such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, etc.
• a neutral salt of such a sulfonic acid with an amine such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonyln
• the content of the amino resin is preferably within the range of 1 to 80 mass %, more preferably within the range of 5 to 70 mass %, and even more preferably within the range of 10 to 65 mass %, based on the total solid content of the curing agent, from the viewpoints of the adhesion, releasability, and releasability after thermal stress of the coating film formed.
• the content of the curing agent is preferably within the range of 0.5 to 50 mass %, more preferably within the range of 1.0 to 45 mass %, and even more preferably within the range of 2.0 to 40 mass %, based on the resin solid content in the peelable automotive water-based paint composition.
• the above pigments include, for example, color pigments, extender pigments, and luster pigments.
• the pigments can be used alone or in combination of two or more.
• the blending amount of the pigment is preferably within the range of 0.1 to 200 parts by mass, more preferably within the range of 1 to 150 parts by mass, and even more preferably within the range of 3 to 120 parts by mass, based on 100 parts by mass of the resin solids in the peelable aqueous automotive paint composition.
• color pigments examples include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, etc.
• titanium oxide and carbon black are preferably used.
• the amount of the coloring pigment is preferably within the range of 1 to 180 parts by mass, more preferably within the range of 5 to 150 parts by mass, and even more preferably within the range of 15 to 120 parts by mass, based on 100 parts by mass of the resin solids in the peelable automotive water-based paint composition.
• examples of the extender pigment include barium sulfate, talc, clay, kaolin, barium carbonate, calcium carbonate, silica, alumina white, etc. From the viewpoint of paint stability and finish, barium sulfate and talc are preferably used as the extender pigment.
• the blending amount of the extender pigment is preferably within the range of 1 to 180 parts by mass, more preferably within the range of 5 to 140 parts by mass, and even more preferably within the range of 10 to 120 parts by mass, based on 100 parts by mass of the resin solids in the peelable automotive water-based paint composition.
• the luster pigment may be, for example, aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, glass flake, aluminum oxide, mica, aluminum oxide coated with titanium oxide and/or iron oxide, mica coated with titanium oxide and/or iron oxide, etc.
• aluminum pigments There are non-leafing aluminum pigments and leafing aluminum pigments, and either can be used.
• the above-mentioned luster pigment is preferably scaly. Furthermore, it is suitable for the luster pigment to have a longitudinal dimension in the range of 1 to 100 ⁇ m, particularly 5 to 40 ⁇ m, and a thickness in the range of 0.001 to 5 ⁇ m, particularly 0.01 to 2 ⁇ m.
• the amount of the luster pigment is preferably within the range of 0.1 to 100 parts by mass, more preferably within the range of 1 to 50 parts by mass, and even more preferably within the range of 3 to 25 parts by mass, based on 100 parts by mass of the resin solids in the peelable automotive water-based paint composition.
• the organic solvent may, for example, be ketone-based solvents such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; ester-based solvents such as ethyl acetate, butyl acetate, methyl benzoate, ethyl ethoxypropionate, ethyl propionate, or methyl propionate; alcohol-based solvents such as isopropanol, n-butanol, isobutanol, or 2-ethylhexanol; ether-based solvents such as tetrahydrofuran, dioxane, or dimethoxyethane; glycol ether-based solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or 3-methoxybutyl acetate; aromatic hydrocarbon-based solvents, aliphatic
• the peelable aqueous automotive paint composition of the present invention When using the peelable aqueous automotive paint composition of the present invention, it can be diluted by adding water and/or an organic solvent, etc. as necessary, and adjusted to the appropriate viscosity before application.
• the appropriate viscosity varies depending on the paint composition, but for example, the viscosity after 1 minute at 60 rpm measured with a B-type viscometer at a temperature of 20°C (sometimes referred to as the "B60 value" in this specification) is preferably in the range of 100 to 3000 mPa ⁇ s, more preferably in the range of 300 to 2000 mPa ⁇ s, and even more preferably in the range of 500 to 1500 mPa ⁇ s, from the viewpoint of the adhesion, peelability, and cracking resistance of the coating film formed.
• the viscometer used here is "LVDV-I" (product name, BROOKFIELD, B-type viscometer).
• the coating solids concentration of the peelable aqueous coating composition for automobiles of the present invention is usually about 5 to 70 mass %, preferably about 10 to 55 mass %.
• the peelable automotive water-based paint composition of the present invention may be either a one-component paint or a multi-component paint, but a one-component paint is preferable from the viewpoints of excellent productivity due to the absence of a paint mixing process and simplification of maintenance of painting machinery.
• the peelable aqueous coating composition for automobiles of the present invention can be used for forming a peelable coating film when forming a multi-layer coating film consisting of a peelable coating film and a clear coat coating film on a substrate such as an automobile body.
• the coating film formation method can be carried out according to the following method I.
• Step (I-1) A step of applying a peelable aqueous coating composition for automobiles onto a substrate to form a peelable coating film
• Step (I-2) A step of drying the peelable coating film formed in the step (I-1)
• a method for forming a multilayer coating film comprising: step (I-3): applying a clear coat paint composition onto the peelable coating film formed in step (I-2) to form an uncured clear coat film; and step (I-4): heat-curing the uncured clear coat film formed in step (I-3).
• substrates include the exterior and interior panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses; automobile parts; and the exterior panels of household electrical appliances such as mobile phones and audio equipment. Of these, the exterior and interior panels of automobile bodies and automobile parts are preferred.
• the materials of these substrates are not particularly limited. Examples include metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, zinc-plated steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.)-plated steel; resins such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, and epoxy resin; plastic materials such as various FRPs; inorganic materials such as glass, cement, and concrete; wood; and fibrous materials such as paper and cloth. Of these, metal materials and plastic materials are preferred.
• metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, zinc-plated steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.)-plated steel
• resins such as polyethylene resin, polypropylene resin, acrylonitrile
• the surfaces of the objects to which the coating film is applied may be metal surfaces such as the outer and inner panels of automobile bodies, automobile parts, household electrical appliances, and the metal substrates such as the steel plates that make up these products, which have been subjected to surface treatments such as phosphate treatment, chromate treatment, and composite oxide treatment.
• a coating film may be further formed on an object that may or may not have been surface-treated.
• a substrate to be coated may be surface-treated as necessary, and an undercoat coating film may be formed on top of it.
• the undercoat coating film may be formed using a known undercoat paint that is normally used in painting automobile bodies.
• an electrodeposition paint preferably a cationic electrodeposition paint, can be used.
• an intermediate coat film, a base coat film and/or a clear coat film may be further applied thereon.
• the intermediate coat film, base coat film and clear coat film may be applied using intermediate coat paint, base coat paint and clear coat paint that are known per se and are normally used in the painting of automobile bodies.
• the intermediate coat film, base coat film and clear coat film may or may not be heat-cured.
• the peelable aqueous coating composition for automobiles can be applied to a substrate by a method known per se, such as air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, etc., and electrostatic application may be performed during coating. Of these, air spray coating and rotary atomization coating are preferred. Furthermore, such coating methods can be performed once or in several separate steps until the desired film thickness is obtained.
• the amount of the peelable automotive water-based paint composition to be applied is preferably an amount that results in a peelable coating film having a dry thickness of 10 to 110 ⁇ m, more preferably an amount that results in a peelable coating film having a dry thickness of 20 to 100 ⁇ m, and even more preferably an amount that results in a peelable coating film having a dry thickness of 30 to 90 ⁇ m, from the viewpoints of the adhesion, peelability, peelability after thermal load, and crack resistance of the coating film to be formed.
• thermosetting clear paint composition any of the thermosetting clear paint compositions known for painting automobile bodies and the like can be used.
• thermosetting clear paint composition include organic solvent-based thermosetting paint compositions containing a base resin having a crosslinkable functional group and a curing agent, water-based thermosetting paint compositions, and powder thermosetting paint compositions.
• organic solvent-based thermosetting paint compositions containing a base resin having a crosslinkable functional group and a curing agent are preferred.
• Examples of the crosslinkable functional groups possessed by the base resin include carboxyl groups, hydroxyl groups, epoxy groups, and alkoxysilyl groups.
• Examples of the types of base resin include acrylic resins, polyester resins, alkyd resins, urethane resins, epoxy resins, and fluororesins.
• Examples of the curing 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.
• Preferred combinations of base resin/curing agent for the above clear coat paint composition include hydroxyl-containing resin/polyisocyanate compound, carboxyl-containing resin/epoxy-containing resin, hydroxyl-containing resin/blocked polyisocyanate compound, hydroxyl-containing resin/melamine resin, etc., with hydroxyl-containing resin/polyisocyanate compound being more preferred.
• the clear coat paint composition may be a one-component paint or a multi-component paint such as a two-component urethane resin paint.
• the clear coat paint composition may contain color pigments, luster pigments, dyes, etc., as needed, to the extent that transparency is not impaired, and may further contain extender pigments, ultraviolet absorbers, light stabilizers, defoamers, thickeners, rust inhibitors, surface conditioners, etc., as appropriate.
• the method for applying the clear coat paint composition is not particularly limited, but a wet coating film can be formed by, for example, air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, or other coating methods. In these coating methods, electrostatic application may be performed as necessary. Of these, air spray coating or rotary atomization coating is particularly preferred.
• the amount of clear coat composition applied is usually preferably an amount that results in a cured film thickness of 10 to 70 ⁇ m, and more preferably an amount that results in a cured film thickness of 20 to 50 ⁇ m.
• the viscosity of the clear coating composition is adjusted appropriately using a solvent such as an organic solvent so that the viscosity is within a range suitable for the coating, usually a range of about 15 to 60 seconds, and particularly about 20 to 50 seconds, at 20°C using a Ford Cup No. 4 viscometer.
• the heating can be performed by known means, for example, a drying oven such as a hot air oven, an electric oven, or an infrared induction heating oven.
• the heating temperature is preferably within the range of 45 to 150°C, more preferably within the range of 50 to 120°C, and even more preferably within the range of 55 to 100°C.
• the heating time is not particularly limited, but is preferably within the range of 10 to 90 minutes, and more preferably within the range of 20 to 75 minutes.
• the aqueous coating composition of the present invention can be used for forming a peelable coating film when forming a multi-layer coating film consisting of a peelable coating film, a base coat coating film and a clear coat coating film on a substrate such as an automobile body.
• the coating film can be formed according to the following method II.
• Step (II-1) A step of applying a peelable aqueous coating composition for automobiles onto a substrate to form a peelable coating film;
• Step (II-2) A step of drying the peelable coating film formed in the step (II-1);
• Step (II-3) A step of applying a base coat paint composition onto the peelable coating film formed in the step (II-2) to form an uncured base coat coating film;
• a method for forming a multilayer coating film comprising: step (II-4): applying a clear coat paint composition onto the uncured base coat film formed in step (II-3) to form an uncured clear coat film; and step (II-5): heating and curing the uncured base coat film formed in step (II-3) and the uncured clear coat film formed in step (II-4) at the same time.
• substrates include the exterior and interior panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses; automobile parts; and the exterior panels of household electrical appliances such as mobile phones and audio equipment. Of these, the exterior and interior panels of automobile bodies and automobile parts are preferred.
• the materials of these substrates are not particularly limited. Examples include metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, zinc-plated steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.)-plated steel; resins such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, and epoxy resin; plastic materials such as various FRPs; inorganic materials such as glass, cement, and concrete; wood; and fibrous materials such as paper and cloth. Of these, metal materials and plastic materials are preferred.
• metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, zinc-plated steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.)-plated steel
• resins such as polyethylene resin, polypropylene resin, acrylonitrile
• the surfaces of the objects to which the coating film is applied may be metal surfaces such as the outer and inner panels of automobile bodies, automobile parts, household electrical appliances, and the metal substrates such as the steel plates that make up these products, which have been subjected to surface treatments such as phosphate treatment, chromate treatment, and composite oxide treatment.
• a coating film may be further formed on an object that may or may not have been surface-treated.
• a substrate to be coated may be surface-treated as necessary, and an undercoat coating film may be formed on top of it.
• the undercoat coating film may be formed using a known undercoat paint that is normally used in painting automobile bodies.
• an electrodeposition paint preferably a cationic electrodeposition paint, can be used.
• an intermediate coat film, a base coat film and/or a clear coat film may be further applied thereon.
• the intermediate coat film, base coat film and clear coat film may be applied using intermediate coat paint, base coat paint and clear coat paint that are known per se and are normally used in the painting of automobile bodies.
• the intermediate coat film, base coat film and clear coat film may or may not be heat-cured.
• the peelable aqueous coating composition for automobiles can be applied to a substrate by a method known per se, such as air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, etc., and electrostatic application may be performed during coating. Of these, air spray coating and rotary atomization coating are preferred. Furthermore, such coating methods can be performed once or in several separate steps until the desired film thickness is obtained.
• the amount of the peelable automotive water-based paint composition to be applied is preferably an amount that results in a peelable coating film having a dry thickness of 10 to 110 ⁇ m, more preferably an amount that results in a peelable coating film having a dry thickness of 20 to 100 ⁇ m, and even more preferably an amount that results in a peelable coating film having a dry thickness of 30 to 90 ⁇ m, from the viewpoints of the adhesion, peelability, peelability after thermal load, and crack resistance of the coating film to be formed.
• the base coat paint composition can be a paint made from a base resin such as an acrylic resin, polyester resin, alkyd resin, urethane resin, or epoxy resin having a crosslinkable functional group such as a carboxyl group or a hydroxyl group, an amino resin such as a melamine resin or a urea resin, or a curing agent such as a polyisocyanate compound which may be blocked, together with a pigment, a thickener, and other optional components.
• a base resin such as an acrylic resin, polyester resin, alkyd resin, urethane resin, or epoxy resin having a crosslinkable functional group such as a carboxyl group or a hydroxyl group, an amino resin such as a melamine resin or a urea resin, or a curing agent such as a polyisocyanate compound which may be blocked, together with a pigment, a thickener, and other optional components.
• the method for applying the base coat paint composition is not particularly limited, but a wet coating film can be formed by, for example, air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, or other coating methods. In these coating methods, electrostatic application may be performed as necessary. Of these, air spray coating or rotary atomization coating is particularly preferred.
• the amount of application of the base coat paint composition is usually preferably an amount that results in a cured film thickness of 5 to 40 ⁇ m, more preferably an amount that results in a cured film thickness of 7 to 35 ⁇ m, and even more preferably an amount that results in a cured film thickness of 10 to 30 ⁇ m.
• thermosetting clear paint composition any of the thermosetting clear paint compositions known for painting automobile bodies and the like can be used.
• thermosetting clear paint composition include organic solvent-based thermosetting paint compositions containing a base resin having a crosslinkable functional group and a curing agent, water-based thermosetting paint compositions, and powder thermosetting paint compositions.
• organic solvent-based thermosetting paint compositions containing a base resin having a crosslinkable functional group and a curing agent are preferred.
• Examples of the crosslinkable functional groups possessed by the base resin include carboxyl groups, hydroxyl groups, epoxy groups, and alkoxysilyl groups.
• Examples of the types of base resin include acrylic resins, polyester resins, alkyd resins, urethane resins, epoxy resins, and fluororesins.
• Examples of the curing 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.
• Preferred combinations of base resin/curing agent for the above clear coat paint composition include hydroxyl-containing resin/polyisocyanate compound, carboxyl-containing resin/epoxy-containing resin, hydroxyl-containing resin/blocked polyisocyanate compound, hydroxyl-containing resin/melamine resin, etc., with hydroxyl-containing resin/polyisocyanate compound being more preferable.
• the clear coat paint composition may be a one-component paint or a multi-component paint such as a two-component urethane resin paint.
• the clear coat paint composition may contain color pigments, luster pigments, dyes, etc., as needed, to the extent that transparency is not impaired, and may further contain extender pigments, ultraviolet absorbers, light stabilizers, defoamers, thickeners, rust inhibitors, surface conditioners, etc., as appropriate.
• the method for applying the clear coat paint composition is not particularly limited, but a wet coating film can be formed by, for example, air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, or other coating methods. In these coating methods, electrostatic application may be performed as necessary. Of these, air spray coating or rotary atomization coating is particularly preferred.
• the amount of clear coat composition applied is usually preferably an amount that results in a cured film thickness of 10 to 70 ⁇ m, and more preferably an amount that results in a cured film thickness of 20 to 50 ⁇ m.
• the viscosity of the clear coating composition is adjusted appropriately using a solvent such as an organic solvent so that the viscosity is within a range suitable for the coating, usually a range of about 15 to 60 seconds, and particularly about 20 to 50 seconds, at 20°C using a Ford Cup No. 4 viscometer.
• the heating can be performed by known means, for example, a drying oven such as a hot air oven, an electric oven, or an infrared induction heating oven.
• the heating temperature is preferably within the range of 45 to 150°C, more preferably within the range of 50 to 120°C, and even more preferably within the range of 55 to 100°C.
• the heating time is not particularly limited, but is preferably within the range of 10 to 90 minutes, and more preferably within the range of 20 to 75 minutes.
• the present invention will be explained in more detail below with reference to manufacturing examples, working examples, and comparative examples. However, the present invention is not limited to these. In each example, “parts” and “%” are based on mass unless otherwise specified. Furthermore, the thickness of the coating film is based on the cured coating film.
• the temperature was raised to 70°C while stirring in a nitrogen stream, and a polymerization initiator solution of 0.15 parts of "VA-057” (product name, Wako Pure Chemical Industries, Ltd., polymerization initiator, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide]) dissolved in 6.7 parts of deionized water was added dropwise over 30 minutes, and the mixture was stirred for 3 hours to carry out the polymerization reaction of the acrylic resin component (polymerizable unsaturated groups). During this time, the temperature was appropriately controlled as necessary.
• VA-057 product name, Wako Pure Chemical Industries, Ltd., polymerization initiator, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide]
• Production Examples 2 to 17 and 21 to 26 In Production Example 1, except that the blending composition was as shown in Table 1 below, the same procedure as in Production Example 1 was performed to obtain acrylic urethane composite resin (A-2) to (A-17) and (A-21) to (A-26) dispersions.
• the temperature was raised to 70°C while stirring in a nitrogen stream, and a polymerization initiator solution of 0.15 parts of "VA-057” (product name, Wako Pure Chemical Industries, Ltd., polymerization initiator, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide]) dissolved in 4.2 parts of deionized water was added dropwise over 30 minutes, and the mixture was stirred for 3 hours to carry out the polymerization reaction of the acrylic resin component (polymerizable unsaturated groups). During this time, the temperature was appropriately controlled as necessary.
• VA-057 product name, Wako Pure Chemical Industries, Ltd., polymerization initiator, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide]
• the monomer emulsion for the shell part described below was dropped over 1 hour, and after aging for 1 hour, 3.8 parts of a 5% aqueous solution of 2-(dimethylamino)ethanol was gradually added to the reaction vessel while cooling it to 30°C, and the mixture was discharged while filtering through a 100 mesh nylon cloth, to obtain an acrylic resin (B-1) particle dispersion liquid with an average particle size of 100 nm and a solid content concentration of 30%.
• the obtained acrylic resin particles had an acid value of 17.2 mg KOH/g and a hydroxyl value of 27.2 mg KOH/g.
• Core monomer emulsion 54 parts of deionized water, 3.1 parts of "ADEKA REASOAP SR-1025", 1 part of allyl methacrylate, 10 parts of styrene, 35 parts of n-butyl acrylate, 10 parts of methyl methacrylate, 20 parts of ethyl acrylate, and 1 part of 2-hydroxyethyl methacrylate were mixed and stirred to obtain a core monomer emulsion.
• Shell monomer emulsion 50 parts of deionized water, 1.8 parts of "ADEKA REASOAP SR-1025", 0.04 parts of ammonium persulfate, 5.3 parts of 2-hydroxyethyl acrylate, 2.6 parts of methacrylic acid, 8 parts of ethyl acrylate, and 7.1 parts of methyl methacrylate were mixed and stirred to obtain a shell monomer emulsion.
• Production Example 28 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube, and a dropping device was charged with 120 parts of deionized water and 0.8 parts of "ADEKA REASOAP SR-1025" (product name, manufactured by ADEKA Corporation, emulsifier, active ingredient 25%), and the mixture was stirred and mixed under a nitrogen stream and heated to 80°C.
• “ADEKA REASOAP SR-1025” product name, manufactured by ADEKA Corporation, emulsifier, active ingredient 25%
• the shell monomer emulsion described below was dropped over 1 hour, and after aging for 1 hour, 3.8 parts of a 5% aqueous solution of 2-(dimethylamino)ethanol was gradually added to the reaction vessel while cooling it to 30°C, and the mixture was discharged while filtering through a 100 mesh nylon cloth, to obtain an acrylic resin (B-2) particle dispersion liquid with an average particle size of 100 nm and a solid content concentration of 30%.
• the obtained acrylic resin particles had an acid value of 17.2 mg KOH/g and a hydroxyl value of 27.2 mg KOH/g.
• Monomer emulsion for core part A monomer emulsion for core part was obtained by mixing and stirring 54 parts of deionized water, 3.1 parts of "ADEKA REASOAP SR-1025", 10 parts of styrene, 36 parts of n-butyl acrylate, 10 parts of methyl methacrylate, 20 parts of ethyl acrylate, and 1 part of 2-hydroxyethyl methacrylate.
• Shell monomer emulsion 50 parts of deionized water, 1.8 parts of "ADEKA REASOAP SR-1025", 0.04 parts of ammonium persulfate, 5.3 parts of 2-hydroxyethyl acrylate, 2.6 parts of methacrylic acid, 8 parts of ethyl acrylate, and 7.1 parts of methyl methacrylate were mixed and stirred to obtain a shell monomer emulsion.
• a crack-resistant cold-rolled steel sheet that had been subjected to a zinc phosphate conversion treatment was electrocoated with "Elecron GT-10" (product name, cationic electrocoating paint, manufactured by Kansai Paint Co., Ltd.) to a dry film thickness of 20 ⁇ m, and heated at 170° C. for 30 minutes to cure the electrocoating film, thereby obtaining a coated object.
• "Elecron GT-10" product name, cationic electrocoating paint, manufactured by Kansai Paint Co., Ltd.
• Each peelable aqueous coating composition for automobiles was applied to the above-mentioned substrate with an applicator to a dry film thickness of 50 ⁇ m to prepare a crack resistance test plate.
• the crack resistance test plate was horizontally dried for 60 minutes under conditions of a temperature of 30° C. and a humidity of 50% RH, after which the coating film was observed and evaluated according to the following evaluation criteria.
• A, B, and C are acceptable.
• the evaluation results are shown in Table 2.
• B Slight cracking is observed at the edge of the coating film (thick film part), but it is not a problem.
• C Slight cracking is observed in areas other than the edges of the coating film, but not at a level that is problematic.
• D Significant cracking was observed throughout the entire coating, and there was clearly a problem.
• Diester compound (C1-2) a diester compound of polyoxyethylene glycol and 2-ethylhexanoic acid, which is a compound represented by the general formula (1) in which R 1 and R 2 are each a 2-ethylpentyl group, R 3 is an ethylene group, and m is 7; the molecular weight is 578; the solid content is 100%;
• Diester compound (C1-2) a diester compound of polyoxyethylene glycol and 2-ethylhexanoic acid, which is a compound represented by the general formula (1) in which R 1 and R 2 are each a 2-ethylpentyl group, R 3 is an ethylene group, and m is 7; the molecular weight is 578; the solid content is 100%;
• “Sannyx PP-200” Trade name, manufactured by Sanyo Chemical Industries, Ltd., polypropylene glycol, molecular weight 200, solid content concentration 100%,
• “Sannyx PP-400” Trade name, manufactured by Sanyo Chemical Industries, Ltd
• Test Coating Plate (S1) A cold-rolled steel plate that had been subjected to a zinc phosphate conversion treatment was electrocoated with "Elecron GT-10" (product name, Kansai Paint Co., Ltd., cationic electrodeposition paint) to a dry film thickness of 20 ⁇ m, and heated at 170° C. for 30 minutes to cure the electrodeposition coating, thereby forming a cured electrodeposition coating film.
• "Elecron GT-10" product name, Kansai Paint Co., Ltd., cationic electrodeposition paint
• TP-65P product name, Kansai Paint Co., Ltd., polyester resin and amino resin-based organic solvent-based midcoat coating composition
• TP-65P product name, Kansai Paint Co., Ltd., polyester resin and amino resin-based organic solvent-based midcoat coating composition
• the peelable automotive water-based paint composition No. 1 obtained in Example 1 was applied to the above-mentioned substrate so that the dry film thickness was 50 ⁇ m, and the substrate was air-dried at 20°C for 30 minutes to form a peelable coating film.
• a clear coat paint composition "Retan PG Eco HS Clear (Q)" (Kansai Paint Co., Ltd., urethane curing, high solids clear paint), was applied to the peelable coating film so that the cured film thickness was 50 ⁇ m, forming an uncured clear coat coating film. After leaving it for 15 minutes, it was heated at 60°C for 60 minutes to simultaneously bake the peelable coating film and the clear coat coating film, and a test coating plate (S1-1) was prepared.
• Test Coated Plate A cold-rolled steel plate that had been subjected to a zinc phosphate conversion treatment was electrocoated with "ELECRON GT-10" (product name, Kansai Paint Co., Ltd., cationic electrodeposition paint) to a dry film thickness of 20 ⁇ m, and heated at 170° C. for 30 minutes to cure the electrodeposition coating, thereby forming a cured electrodeposition coating.
• "TP-65P” product name, Kansai Paint Co., Ltd., polyester resin and amino resin-based organic solvent-based midcoat coating composition
• TP-65P product name, Kansai Paint Co., Ltd., polyester resin and amino resin-based organic solvent-based midcoat coating composition
• the peelable water-based automotive paint composition No. 1 obtained in Example 1 was applied to the substrate to a dry thickness of 50 ⁇ m, and air-dried at 20°C for 30 minutes to form a peelable coating film.
• "Retan WB Eco EV Base” product name, water-based colored base coat paint, manufactured by Kansai Paint Co., Ltd.
• Example 46 to 88 Comparative Examples 5 to 8
• Example 45 except that the type of peelable aqueous automotive coating composition was as shown in Table 3 below, test coated plates (S1-2) to (S1-48) and (S2-2) to (S2-48) were prepared in the same manner as in Example 45.
• Adhesion 100 2 mm x 2 mm cross-hatched patterns were made on the coated surface of each test plate (S1-1) to (S1-48) and (S2-1) to (S2-48) in accordance with JIS K 5600-5-6 (1990), adhesive tape was applied to the surface, and the remaining state of the cross-hatched coating film after the tape was quickly peeled off was examined and adhesion was evaluated according to the following criteria. A and B are acceptable. The evaluation results are shown in Table 3. A: 100 grid-like coating films remain, and no chipping occurs. B: 100 square grid coatings remain, but chipped edges are observed. C: The number of remaining grid-like coating films is 99. D: The number of remaining cross-hatched coating films is less than 98.
• Peelability The edge of each of the test coated panels (S1-1) to (S1-48) and (S2-1) to (S2-48) was peeled off, and both sides of the peeled surface were clamped with an air chuck of an EZ Test EZ-SX (manufactured by Shimadzu Corporation), and the peel strength in the T-peel was measured when 20 mm was peeled off at a speed of 200 mm/min.
• B Peel strength is greater than 4 N/cm and less than 6 N/cm;
• C Peel strength is greater than 6 N/cm and less than 8 N/cm;
• D The peel strength is more than 8 N/cm.

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