Multi-component organic solvent prime coating composition and repair coating method

Abstract

The present invention relates to a multi-component organic solvent-based primer composition obtained by mixing a main component (I) comprising an acrylic polyol (A), a pigment composition (B) and an organic solvent (C), and a curing agent component (II) comprising a polyisocyanate compound, the main component (I) comprising an acrylic polyol (A), a pigment composition (B) and an organic solvent (C), and the curing agent component (II) comprising a polyisocyanate compound. The acrylic polyol (A) contained in the main component (I) contains an acrylic polyol (A1) having a glass transition temperature of 40-70 DEG C and an acrylic polyol (A2) having a glass transition temperature of 0-30 DEG C, and the pigment composition (B) contained in the main component (I) contains barium sulfate and clay as a part of the pigment composition (B).

Description

Technical Field

[0001] The present invention relates to a multi-component organic solvent-based primer composition and a repair coating method using the multi-component organic solvent-based primer composition. Background Art

[0002] Generally, the repair coating of automobile exterior panels includes stripping and sanding the old coating at the damaged area, followed by the application of putty, a second coat of primer (intermediate coat), and a top coat.

[0003] For the second coat of primer coating, a grinding operation is generally performed after coating, but in the case where the smoothness of the substrate is relatively high, such as when the substrate is not putty coated or when coating is performed on a replacement workpiece, the grinding operation (polishing) process can be omitted. In this case, coating is performed in a high dilution rate and low viscosity manner and the smoothness of the coating surface is achieved by using means such as silicone surface conditioners. Patent document 1 discloses a primer coating composition, which is a multi-component organic solvent-based primer coating composition obtained by mixing a main agent component and a curing agent component, characterized in that the main agent component comprises a lactone-modified acrylic polyol, a pigment composition and an organic solvent, the curing agent component contains a polyisocyanate compound, the pigment composition contained in the main agent component comprises talc as a part of the pigment composition, the content of talc is in the range of 50 to 300 parts by mass based on 100 parts by mass of the solid content of the lactone-modified acrylic polyol, and the content of the pigment composition is in the range of 50 to 500 parts by mass based on 100 parts by mass of the solid content of the lactone-modified acrylic polyol.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-96594 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] On the other hand, applying a high dilution ratio to achieve a smooth coating surface can lead to problems such as reduced base coverage and prolonged drying of the coating film. Furthermore, achieving smoothness with silicone-based surface conditioners can lead to problems with wettability of the topcoat (particularly water-based paint).

[0009] The problem to be solved by the present invention is to provide a multi-component organic solvent-based primer composition with good finishing properties (also known as coating properties or smoothness, etc.) and adhesion, excellent base covering properties and drying properties, and a repair coating method using the composition.

[0010] Means of solving the problem

[0011] To solve the above-mentioned problems, the present inventors conducted intensive research and found that the above-mentioned problems can be solved by the following primer composition, thereby completing the present invention. A multi-component organic solvent-based primer composition is obtained by mixing a main component (I) and a curing agent component (II), wherein the main component (I) comprises an acrylic polyol (A), a pigment composition (B), and an organic solvent (C); the curing agent component (II) comprises a polyisocyanate compound; the acrylic polyol (A) contained in the main component (I) comprises an acrylic polyol (A1) having a glass transition temperature of 40 to 70°C and an acrylic polyol (A2) having a glass transition temperature of 0 to 30°C; and the pigment composition (B) contained in the main component (I) comprises barium sulfate and clay as part of the pigment composition (B).

[0012] That is, the present invention provides the following multi-component organic solvent-based primer composition and repair coating method.

[0013] Item 1. A multi-component organic solvent-based primer composition, which is obtained by mixing a main agent component (I) and a curing agent component (II), wherein

[0014] The main agent component (I) comprises acrylic polyol (A), pigment composition (B) and organic solvent (C), and the curing agent component (II) comprises a polyisocyanate compound. The acrylic polyol (A) contained in the main agent component (I) contains an acrylic polyol (A1) having a glass transition temperature of 40 to 70°C and an acrylic polyol (A2) having a glass transition temperature of 0 to 30°C. The pigment composition (B) contained in the main agent component (I) contains barium sulfate and clay as a part of the pigment composition (B).

[0015] Item 2. The primer composition according to Item 1, wherein the solid content ratio of the acrylic polyol (A1) having a glass transition temperature of 40 to 70°C to the acrylic polyol (A2) having a glass transition temperature of 0 to 30°C is 30 / 70 to 99 / 1 by mass.

[0016] Item 3. The primer composition according to Item 1 or Item 2, wherein the content of the pigment composition (B) is in the range of 100 to 300 parts by mass based on 100 parts by mass of the solid content of the acrylic polyol (A).

[0017] Item 4. The primer composition according to any one of Items 1 to 3, wherein the SP value of the acrylic polyol (A) is 8.5 to 9.5 (cal / cm 3 ) 1 / 2 range.

[0018] Item 5. The primer composition according to any one of Items 1 to 4, wherein the main agent component (I) further comprises a surface conditioner having a nonionic hydrophilic group.

[0019] Item 6. The primer composition according to any one of Items 1 to 5, wherein the main agent component (I) further comprises a silane coupling agent.

[0020] Item 7. A method for repairing a coating, comprising: applying the primer composition of any one of items 1 to 6 to the portion to be repaired which is optionally coated with putty (with or without putty) to form 5 m m~50 m m and applying a colored coating composition on the primer coating film.

[0021] Item 8. The repair coating method according to Item 7, wherein the colored coating composition is a water-based coating.

[0022] Item 9. A repair coating method, comprising: applying a primer composition obtained by adding a chlorinated polyolefin to the primer composition according to any one of Items 1 to 6 to a portion to be repaired on a plastic surface.

[0023] Effects of the Invention

[0024] The present invention can provide a multi-component organic solvent-based primer composition with good finishing properties and adhesion, excellent base covering properties and drying properties, and a repair coating method using the same. DETAILED DESCRIPTION

[0025] The primer composition of the present invention is a multi-component composition obtained by mixing a main agent component (I) and a curing agent component (II). The primer composition of the present invention may also be a multi-component composition obtained by mixing three or more components other than the main agent component (I) and the curing agent component (II), as needed.

[0026] Next, each component used in the present invention will be described.

[0027] <Acrylic polyol (A)>

[0028] In the present invention, the main agent component (I) contains acrylic polyol (A).

[0029] The acrylic polyol (A) in the present invention is a component that can serve as a coating film-forming component together with the polyisocyanate compound described below. Any conventionally known material can be used without limitation as long as it exhibits organic solvent dilution and coating film-forming properties. For example, it can be a copolymer of a polymerizable unsaturated monomer containing a hydroxyl group-containing polymerizable unsaturated monomer as an essential component and at least one (meth)acryloyl monomer.

[0030] Examples of the hydroxyl-containing polymerizable unsaturated monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate; ε-caprolactone-modified forms of the above hydroxyalkyl (meth)acrylates; hydroxyl-containing (meth)acryloyl monomers such as (meth)acrylates containing a polyoxyethylene chain having a hydroxyl group at the molecular end; and allyl alcohol. These monomers may be used alone or in combination of two or more.

[0031] Examples of the polymerizable unsaturated monomer containing a (meth)acryloyl group monomer copolymerized with the hydroxyl-containing polymerizable unsaturated monomer include: linear or branched alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; alicyclic alkyl (meth)acrylates such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate; perfluoroalkyl (meth)acrylates; N,N-dialkylaminoalkyl (meth)acrylates such as N,N-diethylaminoethyl (meth)acrylate; (meth)acrylamide; Allyl methacrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol di(meth)acrylate (Meth)acryloyl monomers having at least two polymerizable unsaturated groups in one molecule, such as ester, 1,1,1-trimethylolethane di(meth)acrylate, 1,1,1-trimethylolethane tri(meth)acrylate, 1,1,1-trimethylolpropane tri(meth)acrylate; (meth)acrylic acid; (meth)acryloyl monomers containing carbonyl groups, such as acetoacetoxyethyl (meth)acrylate and diacetone (meth)acrylamide; glycidyl (meth)acrylate, (meth)acrylic acid β - Epoxy-containing (meth)acryl monomers such as methyl glycidyl ester, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, and 3,4-epoxycyclohexylpropyl (meth)acrylate; isocyanate-containing (meth)acryl monomers such as ethyl isocyanate (meth)acrylate; c -Methacryloxypropyltrimethoxysilane, c - (Meth)acryl monomers containing alkoxysilyl groups, such as methacryloxypropyltriethoxysilane; (Meth)acryl monomers containing oxidatively curable groups, such as dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyloxypropyl (meth)acrylate, and dicyclopentenyl (meth)acrylate. These can be used alone or in combination of two or more.

[0032] In addition, examples of other copolymerizable polymerizable unsaturated monomers other than the (meth)acryloyl monomer include: (meth)acrylonitrile; vinyl ester compounds such as vinyl acetate and vinyl propionate; styrene, α - Vinyl aromatic compounds such as methyl styrene; polyvinyl compounds with at least two polymerizable unsaturated groups in one molecule such as triallyl isocyanurate, diallyl terephthalate, and divinylbenzene; maleic acid, crotonic acid, acrylic acid β -carboxyethyl ester and other carboxyl group-containing polymerizable unsaturated monomers; (meth) acrolein, formylstyrene, vinyl alkyl ketones having 4 to 7 carbon atoms (such as vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone, etc.), acetoacetoxy allyl ester and other carbonyl group-containing polymerizable unsaturated monomers; allyl glycidyl ether and other epoxy group-containing polymerizable unsaturated monomers; m-isopropenyl- α,α - Isocyanate group-containing polymerizable unsaturated monomers such as dimethylbenzyl isocyanate; alkoxysilyl group-containing polymerizable unsaturated monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; oxidatively curable group-containing polymerizable unsaturated monomers such as the reaction product of an epoxy group-containing polymerizable unsaturated monomer or a hydroxyl group-containing polymerizable unsaturated monomer with an unsaturated fatty acid; etc. These may be used alone or in combination of two or more.

[0033] The acrylic polyol (A) has a weight average molecular weight preferably in the range of 5,000 to 80,000, more preferably 6,000 to 70,000, and a solid content hydroxyl value preferably in the range of 200 mgKOH / g or less, more preferably 50 to 150 mg / KOH, from the viewpoint of adhesion of the resulting coating film.

[0034] In this specification, the weight-average molecular weight is a value calculated based on the weight-average molecular weight of polystyrene, as measured using a gel permeation chromatograph ("HLC8120GPC," manufactured by Tosoh Corporation). The measurement was performed under the following conditions: four columns were used: "TSKgel G-4000H×L," "TSKgel G-3000H×L," "TSKgel G-2500H×L," and "TSKgel G-2000H×L" (all trade names manufactured by Tosoh Corporation), the mobile phase was tetrahydrofuran, the measurement temperature was 40°C, the flow rate was 1 ml / min, and the detector was RI.

[0035] From the viewpoint of dilutability with organic solvents and compatibility with the chlorinated polyolefin described below, it is preferred that the solubility parameter (SP value) of the acrylic polyol (A) be 8.5 to 9.5 (cal / cm 3 ) 1 / 2The range is more preferably 8.5 to 9.0 (cal / cm 3 ) 1 / 2 range.

[0036] In this specification, the solubility parameter (abbreviated as "SP value") represents a measure of the intermolecular interactions between liquid molecules. The SP value of a homopolymer of a polymerizable monomer is described in "J. Paint Technology," Vol. 42, p. 176 (1970). The SP value of a copolymer of a polymerizable monomer mixture can be calculated using the following formula.

[0037] SP value = SP1×fw1+SP2×fw2+………+SPn×fwn

[0038] In the above formula, SP1, SP2, ..., SPn represent the SP value of the homopolymer of each polymerizable monomer, and fw1, fw2, ..., fwn represent the mass fraction of each polymerizable unsaturated monomer relative to the total amount of monomers.

[0039] The acrylic polyol (A) is preferably contained in an amount of 75% by mass or more, more preferably 85% by mass or more, in the resin solid content contained in the main agent component (I).

[0040] In this specification, solid content or non-volatile matter refers to the residue after removing volatile components. The residue can be solid or liquid at room temperature. For example, it refers to the residue after treating a sample at 105°C for 3 hours to remove volatile components.

[0041] The content of the acrylic polyol (A) in the main agent component (I) is preferably in the range of 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 10 to 30 parts by mass in terms of non-volatile content, based on 100 parts by mass of the total mass of the main agent component (I).

[0042] In the present invention, the acrylic polyol (A) contains an acrylic polyol (A1) having a glass transition temperature of 40 to 70°C and an acrylic polyol (A2) having a glass transition temperature of 0 to 30°C.

[0043] In this specification, the glass transition temperature (Tg) is a value calculated by the following formula.

[0044] 1 / Tg(K)=W1 / T1+W2 / T2+……Wn / Tn

[0045] Tg(℃)=Tg(K)-273

[0046] Wherein, W1, W2, ..., Wn are the mass fractions of the respective monomers, and T1, T2, ..., Tn are the glass transition temperatures Tg (K) of the homopolymers of the respective monomers. The glass transition temperatures of the homopolymers of the respective monomers are based on the values ​​in "Polymer Handbook Fourth Edition" (1999) (edited by J. Brandrup, Eh Immergut, and E.A. Grulke). The glass transition temperatures of monomers not described in this document are set to the static glass transition temperatures when synthesizing homopolymers of the respective monomers to have a weight-average molecular weight of approximately 50,000.

[0047] In this specification, the static glass transition temperature of a resin can be measured, for example, by placing a sample in a measuring cup, completely removing the solvent by vacuum suction, and then using a differential scanning calorimeter "DSC-50Q" (trade name, manufactured by Shimadzu Corporation) to measure the change in heat (calorific value) in the range of -100°C to 150°C at a heating rate of 3°C / min, and the initial baseline change point on the low temperature side is defined as the static glass transition temperature.

[0048] An acrylic polyol (A1) having a glass transition temperature of 40 to 70°C is effective in improving the drying properties of the coating film, and a glass transition temperature in the range of 45 to 65°C is more preferred.

[0049] The content of the acrylic polyol (A1) having a glass transition temperature of 40 to 70° C. is preferably 30 to 95% by mass, more preferably 50 to 90% by mass, based on 100 parts by mass of the resin solid content of the acrylic polyol (A) contained in the main component (I).

[0050] The acrylic polyol (A1) having a glass transition temperature of 40 to 70° C. may be a single resin or a combination of two or more resins.

[0051] The acrylic polyol (A2) having a glass transition temperature of 0 to 30°C is effective in improving the finish of the coating film, and the acrylic polyol (A2) having a glass transition temperature of 5 to 25°C is more preferably used.

[0052] The content of the acrylic polyol (A2) having a glass transition temperature of 0 to 30° C. is preferably 5 to 70% by mass, more preferably 10 to 50% by mass, based on 100 parts by mass of the resin solid content of the acrylic polyol (A) contained in the main component (I).

[0053] The acrylic polyol (A2) having a glass transition temperature of 0 to 30° C. may be a single resin or a combination of two or more resins.

[0054] The solid content ratio of the acrylic polyol (A1) having a glass transition temperature of 40 to 70°C to the acrylic polyol (A2) having a glass transition temperature of 0 to 30°C is preferably 30 / 70 to 99 / 1, more preferably 45 / 55 to 95 / 5, and particularly preferably 60 / 40 to 90 / 10 in terms of mass ratio.

[0055] The acrylic polyol (A) may contain acrylic polyols other than the acrylic polyol (A1) having a glass transition temperature of 40 to 70°C and the acrylic polyol (A2) having a glass transition temperature of 0 to 30°C.

[0056] <Pigment Composition (B)>

[0057] In the present invention, the main agent component (I) comprises a pigment composition (B), and as a part of the pigment composition (B), barium sulfate and clay are contained as an extender pigment.

[0058] Since the pigment composition (B) contains barium sulfate and clay, the drying properties of the coating film and the coating workability are improved.

[0059] In the present invention, the barium sulfate and clay can be any known extender pigments used in the coating field, and may be synthetic or natural, or may be surface-treated as needed. Furthermore, there is no limitation on their shape or size.

[0060] The amounts of barium sulfate and clay to be added are preferably in the range of 5 to 200 parts by mass, more preferably 10 to 150 parts by mass, and the amount of clay to be added is preferably in the range of 5 to 100 parts by mass, more preferably 10 to 80 parts by mass, based on 100 parts by mass of the solid content of the acrylic polyol (A).

[0061] Furthermore, the pigment composition (B) may contain known pigments such as extender pigments, coloring pigments, and rust-proof pigments in addition to barium sulfate and clay, as needed.

[0062] Examples of other extender pigments include talc, barium carbonate, aluminum silicate, gypsum, calcium carbonate, silica, white carbon, diatomaceous earth, magnesium carbonate, aluminum oxide white, glossy white, and mica powder.

[0063] Examples of coloring pigments include white pigments such as titanium dioxide; black pigments such as carbon black, acetylene black, lamp black, bone black, graphite, iron black, and aniline black; yellow pigments such as iron oxide yellow, titanium yellow, monoazo yellow, condensed azo yellow, azomethine yellow, bismuth vanadate, benzimidazolone, isoindolinone, isoindolinone, quinophthalone, benzidine yellow, and permanent yellow; orange pigments such as permanent orange; red pigments such as red iron oxide, naphthol AS-based azo red, anthraquinone, anthraquinone red, perylene maroon, quinacridone red pigment, dione pyrrolopyrrole, calcium red, and permanent red; violet pigments such as cobalt violet, quinacridone violet, and dioxazine violet; cobalt blue, phthalocyanine blue, and vat sky blue. Blue pigments such as phthalocyanine green; green pigments such as phthalocyanine green; metallic pigments such as aluminum powder, bronze powder, copper powder, tin powder, iron phosphide, and zinc powder; and pearlescent pigments such as metal oxide-coated mica powder and mica-like iron oxide. These pigments can be used alone or in combination of two or more.

[0064] When the primer composition of the present invention contains a color pigment, from the viewpoint of hiding power and the finished appearance of the top coat, the mass of the color pigment is 1 or more and less than 300 parts by mass, preferably 2 to 250 parts by mass, more preferably 3 to 200 parts by mass, based on 100 parts by mass of the total amount of barium sulfate and clay.

[0065] In the present invention, the content of the pigment composition (B) is preferably in the range of 100 to 300 parts by mass, more preferably in the range of 150 to 250 parts by mass, based on 100 parts by mass of the resin solid content of the acrylic polyol (A) contained in the main component (I). This is suitable from the viewpoints of the adhesion strength of the base coating film and the appearance of the finished product after top coating.

[0066] <Organic Solvent (C)>

[0067] In the present invention, as the organic solvent (C), for example, organic compounds having a molecular weight in the range of 58 to 220, particularly in the range of 72 to 200, can be cited. Those well-known in the field of coatings can be used without restriction, and for example, it is preferred to include at least one organic solvent selected from ester organic solvents and ketone organic solvents.

[0068] Examples of the ester organic solvents include ethyl acetate, butyl acetate, isobutyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, 3-methoxybutyl acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and diethylene glycol monoethyl ether acetate. Examples of the ketone organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl isoamyl ketone, diisobutyl ketone, methyl hexyl ketone, and isophorone. These organic solvents may be used alone or in combination of two or more.

[0069] The amount of at least one organic solvent selected from the ester organic solvents and ketone organic solvents used is preferably 5% by mass or more, particularly preferably 20% by mass or more, of the total organic solvents contained in the primer composition of the present invention.

[0070] In the present invention, as other organic solvents other than the above-mentioned ester organic solvents and ketone organic solvents, there can be mentioned: straight-chain alkanes such as n-butane, n-hexane, n-heptane, n-pentane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, and n-heptadecane; 2-methylbutane, 2,2-dimethylpropane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpropane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2,4-dimethylpropane, 2-methylpentane, 3-methylpentane, 2,3-dimethylpentane, 2,4-dimethylpropane, 2 ... Branched-chain alkanes such as methylpentane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, 3,4-diethylhexane, 2,6-dimethyloctane, 3,3-dimethyloctane, 3,5-dimethyloctane, 4,4-dimethyloctane, 3-ethyl-3-methylheptane, 2-methylnonane, 3-methylnonane, 4-methylnonane, 5-methylnonane, 2-methylundecane, 3-methylundecane, 2,2,4,6,6-pentamethylheptane; cyclopentane, tert-naphthalene, cyclohexane, methylcyclohexane, ethylcyclohexane, 1,2-dimethylcyclohexane Aliphatic hydrocarbon organic solvents such as hexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, propylcyclohexane, isopropylcyclohexane, 1,2-methylethylcyclohexane, 1,3-methylethylcyclohexane, 1,4-methylethylcyclohexane, 1,2,3-trimethylcyclohexane, 1,2,4-trimethylcyclohexane and 1,3,5-trimethylcyclohexane; aromatic hydrocarbon organic solvents such as toluene and xylene; dioxane, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-isopropyl ether, ethylene glycol mono-n-propyl Ether organic solvents such as butyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol monoisopropyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol monoisobutyl ether, diethylene glycol mono-tert-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol monoisopropyl ether; alcohol organic solvents such as methanol, isopropanol, tert-butanol, sec-butanol, isobutanol, n-butanol, 2-ethylhexanol, n-octanol, and benzyl alcohol.

[0071] The organic solvent (C) can be added as a polymerization solvent or dilution solvent in the production of the acrylic polyol (A), or can be added for dilution in the production of the main component (I).

[0072] <Polyisocyanate Compound>

[0073] In the present invention, a polyisocyanate compound is a polyisocyanate compound having two or more isocyanate groups per molecule. Specific examples include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylenediisocyanate, xylylenediisocyanate, tetramethyl-m-xylylenediisocyanate, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and lysine diisocyanate; adducts of these polyisocyanates with polyols, low-molecular-weight polyester resins, or water; or cyclic polymers of the aforementioned polyisocyanates and isocyanate-biuret compounds. These compounds may be used alone or in combination of two or more.

[0074] <Main Agent Component (I)>

[0075] In the present invention, the main agent component (I) comprises acrylic polyol (A), a pigment composition (B) and an organic solvent (C).

[0076] In the present invention, the nonvolatile content of the main component (I) is preferably in the range of 50 to 90% by mass, particularly 60 to 80% by mass, from the viewpoint of coating workability and finish of the formed coating film.

[0077] The main component (I) can have a low viscosity compared to its solid content and can exhibit excellent coating workability. Specifically, the viscosity in the storage state (sealed can state) can preferably be in the range of 75 to 140 KU, and more preferably in the range of 80 to 120 KU.

[0078] In this specification, the viscosity is the viscosity of a sample adjusted to 25° C. and measured using a Stormer viscometer.

[0079] <Curing agent component (II)>

[0080] In the present invention, the curing agent component (II) contains the above-mentioned polyisocyanate compound (D).

[0081] From the viewpoint of coating operability and miscibility with the main agent component (I), the curing agent component (II) preferably contains an organic solvent. As the organic solvent, it can be appropriately selected from the compounds exemplified in the description of the above-mentioned organic solvent (C). From the viewpoint of coating operability and the finish of the coating film, the non-volatile matter concentration of the curing agent component (II) is preferably in the range of 5 to 90% by mass, particularly in the range of 20 to 60% by mass.

[0082] <Other additives>

[0083] The primer composition of the present invention may further contain the following coating additives as appropriate: a viscosity modifier (rheology modifier), a curing catalyst, cellulose acetate butyrate and its modified products, a modifying resin other than the acrylic polyol (A) such as a polyester resin, an alkyd resin, or a polyurethane resin, a pigment dispersant, a surface conditioner, resin particles, etc. These additives may be contained in either the main component (I) or the curing agent component (II), but from the viewpoint of storage stability, it is preferred that the main component (I) contain an additive capable of reacting directly with the isocyanate compound.

[0084] The base coating composition of the present invention preferably further comprises a surface conditioner having a nonionic hydrophilic group. When the base coating composition comprises a surface conditioner having a nonionic hydrophilic group, the finish of the base coating composition in forming the coating film and the wettability of the top coating to the base coating composition are improved, thereby improving the finish of the final coating film. The surface conditioner having a nonionic hydrophilic group may be included in either the main component (I) or the curing agent component (II) described below. However, since storage stability is improved when the main component (I) comprises a surface conditioner having a nonionic hydrophilic group, it is preferably included in the main component (I).

[0085] Specific examples of the nonionic hydrophilic group include polyoxyalkylene groups such as a polyoxyethylene group, a polyoxypropylene group, and a polyoxyethylene (oxypropylene) group.

[0086] As the surface conditioner having a nonionic hydrophilic group, substances known in the field of coatings can be used without limitation. There are no particular limitations on the synthesis method, materials used, etc., and commercially available products can also be used.

[0087] The content of the surface conditioner having a nonionic hydrophilic group is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the acrylic polyol (A) resin solid content contained in the main component (I).

[0088] From the viewpoint of improving adhesion, the main agent component (I) preferably contains a silane coupling agent. There is no particular limitation on the type of silane coupling agent, and examples thereof include: 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)methyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)methyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)methyldimethoxysilane and other epoxy-containing silane coupling agents; 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)methyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)methyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)methyldimethoxysilane; Silane coupling agents containing amino groups, such as aminopropyltriethoxysilane, N-2(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2(aminoethyl)-3-aminopropylmethyldimethoxysilane; silane coupling agents containing mercapto groups, such as 3-mercaptopropyltrimethoxysilane; silane coupling agents containing vinyl groups, such as vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(methoxyethoxy)silane; and silane coupling agents containing (meth)acryloyl groups, such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, and 3-(meth)acryloxypropyldimethoxymethylsilane. These agents may be used in combination of two or more. Among these, epoxy-containing silane coupling agents are preferred.

[0089] The content of the silane coupling agent is preferably in the range of 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the resin solid content of the acrylic polyol (A) contained in the main component (I).

[0090] In the case where the silane coupling agent does not have a hydroxyl group, the curing agent component (II) described later may also contain a silane coupling agent.

[0091] The main component (I) preferably contains a viscosity adjuster. As the viscosity adjuster, conventionally known ones can be used, and amide viscosity adjusters are particularly preferably used.

[0092] The use of an amide viscosity modifier improves the storage stability of the main component (I) and the coating workability of the primer composition of the present invention, while also increasing the adhesion strength of the primer composition to the top coating film.

[0093] As such an amide viscosity modifier, substances known in the field of coatings can be used without limitation. There are no particular limitations on the synthesis method, materials used, etc., and commercially available products can also be used.

[0094] Specifically, the following can be cited: fatty acid monoamides synthesized by dehydration of fatty acid ammonium salts or aminolysis of oils (esters); fatty acid diamides (bisamides) synthesized by the condensation reaction of fatty acid amides and formaldehyde, the thermal condensation reaction of monocarboxylic acids and diamines, or the thermal condensation reaction of dibasic acids and monoamines; polycondensation of dimer acids obtained by the polycondensation of dibasic acids and diamines, the polycondensation of diamine derivatives and dibasic acids, the polycondensation of diamines and dibasic acid derivatives or unsaturated fatty acids, or fatty acid polyamides obtained by ring-opening polymerization of lactams; and the like.

[0095] Such amide viscosity modifiers may be those obtained by diluting with a diluent such as an organic solvent. In the present invention, the content of the active ingredient (excluding the diluent) of the amide viscosity modifier is preferably in the range of 0.1 to 15 parts by mass, more preferably in the range of 0.5 to 8 parts by mass, based on 100 parts by mass of the solid content of the acrylic polyol (A).

[0096] In addition, as a curing catalyst, conventionally known urethanization catalysts can be used without particular limitation, and examples thereof include: bismuth nitrate, lead oleate, tin octoate, dibutyltin dilaurate, dibutyltin bis(acetylacetonate), dibutyltin diacetate, dibutyltin octoate, dioctyltin dilaurate, dioctyltin dineodecanoate, titanium tetrachloride, dibutyltitanium dichloride, tetrabutyl titanate (also called "tetrabutoxytitanium"), ferric chloride, zinc octoate and other metal compounds, tertiary amines, and the like.

[0097] The curing catalyst may be contained in either the main component (I) or the curing agent component (II). However, when contained in the main component (I), the content of the curing catalyst is preferably in the range of 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the solid content of the acrylic polyol (A). This is suitable from the viewpoint of improving the curability of the primer composition of the present invention and suppressing the increase in viscosity after mixing the main component (I) and the curing agent component (II).

[0098] <Primer Coating Composition>

[0099] In the primer composition of the present invention, the main agent component (I) and the curing agent component (II) are blended in a ratio such that the isocyanate groups in the curing agent component (II) are preferably in the range of 0.8 to 4.0 equivalents, more preferably 1.0 to 3.5 equivalents, per 1 equivalent of the hydroxyl groups in the main agent component (I).

[0100] The primer composition of the present invention is a two-component composition in which each component is stored separately. Generally, the components are mixed immediately before coating and a thinner is used to adjust the viscosity as needed for use.

[0101] The present invention also provides a repair coating method for base coating using the primer composition.

[0102] Examples of repair coatings applicable to the method of the present invention include coatings applied to exterior panels of automobiles and household appliances. These are often multilayer coatings consisting of a basecoat, a middlecoat (which may be omitted), and a topcoat. Furthermore, each of these coatings may be either solid or metallic. Each of these coatings may be either a three-dimensional crosslinked cured coating or a non-crosslinked coating.

[0103] In the method of the present invention, the damaged portion of the coating is first scraped off, and then the damaged portion is polished around the damaged portion as needed, and then degreased as needed. If there are streaks or spots, the primer composition of the present invention can be applied directly to the degreased portion.

[0104] The primer composition of the present invention can be applied by conventional coating methods, and is particularly suitable for spraying. The coating film thickness of the primer composition of the present invention is preferably in the range of 5 to 50 mm in dry film thickness. m The range of m is more preferably 10 to 45 m The range of m is particularly preferably 15 to 40 m Since the primer composition of the present invention can form a coating film with good finish, the grinding operation (polishing) step for adjusting the surface can be omitted.

[0105] The drying conditions may be, for example, 5 to 40° C., preferably 10 to 30° C., for example, 20 to 120 minutes, preferably 30 to 90 minutes.

[0106] In the top coating, conventionally known coating methods include one-coat finishing (one-coat finishing) using only a colored base paint prepared by blending metallic pigments and / or coloring pigments, or two-coat finishing (two-coat finishing) using the colored base paint and a clear paint.

[0107] As the colored base coating, any top coating such as an organic solvent-based topcoat or water-based topcoat commonly used in repair can be used without particular limitation, and coating can be performed by known coating methods such as spraying, electrostatic spraying, brushing, and roller coating.

[0108] When the colored primer is applied multiple times, flash drying (or "air drying") (allowing the coating to stand at room temperature after application), air blowing, or preheating steps may be provided between each application as needed.

[0109] There are no particular restrictions on the drying of the colored base paint after coating. In the case of overlapping topcoat clearcoat, it can be left in an uncured state. Generally, it is preferably dried at a temperature of 20 to 100°C for 5 to 60 minutes. The film thickness can be adjusted appropriately according to the state of the coated surface. Generally, the dry film thickness is preferably 5 to 100. m m, particularly preferably 10 to 60 m The range of m.

[0110] As the top-coat clear coating, any conventionally known coating can be used without particular limitation. For example, a curable coating having an acrylic resin or fluororesin containing a crosslinking functional group such as a hydroxyl group as a main component and a blocked polyisocyanate, polyisocyanate, or melamine resin as a curing agent, or a lacquer composition having an acrylic resin modified with cellulose acetate butyrate as a main component can be preferably used. Furthermore, coating additives such as pigments, fiber derivatives, additive resins, ultraviolet absorbers, light stabilizers, surface conditioners, and curing catalysts can be contained as needed.

[0111] The top clear coating is dried at a temperature of 20 to 100°C, preferably 40 to 100°C, for 5 to 60 minutes. The film thickness can be adjusted appropriately depending on the state of the surface to be coated. Generally, the dry film thickness is preferably 5 to 100 minutes. m m, particularly preferably 10 to 60 m The range of m.

[0112] <Coating of plastic surfaces>

[0113] The primer composition of the present invention can be enhanced in adhesion to plastic surfaces by adding a chlorinated polyolefin. The chlorinated polyolefin can be pre-incorporated into the main component (I) and the curing agent component (II), or can be added during the mixing of the main component (I) and the curing agent component (II).

[0114] From the viewpoint of compatibility with the coating composition, the chlorinated polyolefin is preferably a modified chlorinated polyolefin, and particularly preferably a maleic anhydride-modified chlorinated polyolefin. As commercially available products, for example, "Superchlon 422S", "Superchlon 892L", "Superchlon 892SL", "Superchlon 822", "Superchlon 822S", "Superchlon 921S", "Superchlon 930", "Superchlon 930S", "Superchlon 842LM", "Superchlon 851L", "Superchlon 3228S", "Superchlon 3221S", "Superchlon 2319S" (trade names, maleic anhydride-modified chlorinated polyolefin, manufactured by Nippon Paper Industries, Ltd.), "Hardlen CY-9122P", "Hardlen CY-9124P", "Hardlen HM-21P", "Hardlen CY-1321P", "Hardlen CY-2121P", "Hardlen CY-2129P", "Hardlen F-225P", "Hardlen F-7P", "Hardlen M-28P", "Hardlen F-2P", "Hardlen F-6P", "Hardlen CY-1132" (trade names, manufactured by Toyobo Co., Ltd., maleic anhydride-modified chlorinated polyolefin), and other commercially available products, two or more of which may be used in combination.

[0115] The content of the chlorinated polyolefin is preferably in the range of 0.1 to 20 parts by mass, more preferably in the range of 0.5 to 15 parts by mass, based on 100 parts by mass of the resin solid content of the acrylic polyol (A) contained in the main component (I), which is suitable from the viewpoint of adhesion strength.

[0116] If chlorinated polyolefin is added to impart adhesion to the plastic surface, the use of a primer, which is typically required when painting the plastic surface, becomes unnecessary, thereby improving work efficiency.

[0117] example

[0118] Below, the present invention is further described in detail by examples. However, the present invention is not limited to these examples. In addition, the meaning of "parts" and "%" in the following examples refers to "parts by mass" and "mass %" respectively.

[0119] Preparation Example 1 Synthesis of Acrylic Polyol (A-1)

[0120] 52 parts of butyl acetate were added to a reaction vessel, and the temperature was raised to 110°C while stirring. A monomer mixture consisting of 10 parts of styrene, 10 parts of methyl methacrylate, 5 parts of n-butyl methacrylate, 60 parts of isobutyl methacrylate, 1 part of methacrylic acid, 14 parts of 2-hydroxyethyl methacrylate, and 2.3 parts of azobisisobutyronitrile, along with a polymerization initiator, was added dropwise at a constant rate over 3 hours at or below 110°C using a dropwise pump. After the addition was complete, the temperature was maintained at 110°C for 60 minutes while stirring was continued. Next, a solution of 0.5 parts of azobisisobutyronitrile dissolved in 7 parts of butyl acetate was added dropwise at a constant rate over 60 minutes as an additional catalyst. After the addition was complete, the temperature was maintained at 110°C for 60 minutes to terminate the reaction. The obtained acrylic polyol solution (A-1) was a uniform yellow transparent solution with a non-volatile content of 55%. The weight average molecular weight of the resin was 18,000, the acid value (AV) was 6.5 mgKOH / g, the hydroxyl value (OHV) was 60 mgKOH / g, and the SP value was 8.7 (cal / cm 3 ) 1 / 2 , the glass transition temperature (Tg) is 61℃.

[0121] Production Examples 2 to 7

[0122] Except having used the compounding composition shown in Table 1, it carried out similarly to the said Production Example 1, and obtained the acrylic polyol solution (A-2) - (A-7).

[0123] Table 1

[0124] Example 1 Preparation of Primer Coating Composition (X-1)

[0125] To 150 parts of an acrylic polyol solution (A-1) with a solid content of 55% (83 parts of resin solid content), 26 parts of an acrylic polyol solution (A-5) with a solid content of 65% (17 parts of resin solid content), 55 parts of butyl acetate, 1 part of a pigment dispersant, 10 parts of titanium white, 2 parts of carbon, 120 parts of barium sulfate, 40 parts of clay, 0.5 parts of a surface conditioner containing a nonionic hydrophilic group, c -3 parts of glycidyloxypropyltrimethoxysilane (silane coupling agent), 0.5 parts of dibutyltin dilaurate, and 5 parts of amide thickener (fatty acid amide, amide viscosity regulator, active ingredient 20%) were mixed and stirred, and dispersed for 30 minutes to obtain the main agent component.

[0126] 25 parts of a polyisocyanate compound (trade name "Sumidur N3390EA", manufactured by Sumika Bayer Urethane Co., Ltd.) and 50 parts of butyl acetate were mixed and stirred to obtain a curing agent component.

[0127] Immediately before use, 100 parts of the main agent component and 20 parts of the curing agent component were mixed to obtain a primer composition (X-1).

[0128] Examples 2 to 17, Comparative Examples 1 to 8

[0129] Except having used the compounding compositions described in Tables 2 to 5, it carried out similarly to the said Example 1, and obtained the primer composition (X-2) - (X-25).

[0130] Table 2

[0131] Table 3

[0132] Table 4

[0133] Table 5

[0134] <Performance Test>

[0135] In the following performance tests, if even one of the ratings was "C", the coating composition was deemed unacceptable.

[0136] Finishing test

[0137] On a mild steel plate (low carbon steel plate) with an electrodeposition coating of 300 mm × 100 mm × 0.8 mm, each primer composition obtained in the Examples and Comparative Examples was used as a second primer, and a diluent was used to prepare the coating so that the solid content was 50% and the dry film thickness was 30 m Spray the coating in the form of 1 / 4" (1 / 2") m and then dry at 20°C for 60 minutes. m The uncured coating was left to stand at room temperature for 5 minutes to obtain a dry film thickness of 40 m. m"Retan PG Eco HX (Q) Clear" (trade name, two-component topcoat clear coating for automotive refinishing, manufactured by Kansai Paint Co., Ltd.) was air-sprayed in a 1 / 4-meter (m) format. After standing at room temperature for 10 minutes, the panels were heated in a hot air circulation drying oven at 60°C for 20 minutes to obtain test panels. The appearance of each test-coated panel was then observed from an oblique side (diagonal direction) and evaluated according to the following evaluation criteria.

[0138] S: Glossiness (glossiness) and coating smoothness are very good; A: Good gloss and coating smoothness; B: Glossiness and coating smoothness are slightly poor; C: Glossiness and coating surface smoothness are poor.

[0139] Adhesion test

[0140] On a mild steel plate of 300mm×100mm×0.8mm, so that the dry film thickness becomes 60 m The primer compositions obtained in the above examples and comparative examples were sprayed in a manner of m, and then dried at 20°C for more than 60 minutes on the cured coating film to a dry film thickness of 15 m "Retan PG Hybrid Eco #202 Sun Metallicbase" (trade name, one-component car repair topcoat, manufactured by Kansai Paint Co., Ltd.) was air-sprayed in a 40-μm manner. After coating, the uncured coating was left to stand at room temperature for 5 minutes to obtain a dry film thickness of 40 μm. m m method, air spraying "Retan PG EcoHX (Q) Clear" (trade name, two-component top coating clear paint for automobile repair, manufactured by Kansai Paint Co., Ltd.). After standing at room temperature for 10 minutes, it was heated at 60°C for 20 minutes in a hot air circulation drying oven to obtain a test plate. A cross-cut adhesion test (cross-cut adhesion test) in accordance with JIS K5600 was performed on the test coated plate. Specifically, 100 grid-shaped cuts that reached the material texture were cut in the coating film in a checkerboard pattern at intervals of 2 mm in the vertical and horizontal directions, and a tape with an adhesive strength of 120 gf / 10 mm was pasted on it. Then, the tape was peeled off instantly, and the number of coating film pieces attached to the tape after peeling was investigated, and evaluated according to the following criteria.

[0141] A: There is no peeling between the base coating and the metal base coating or between the mild steel plate and the base coating; B: The peeling number between the base coating and the metal base coating or between the mild steel plate and the base coating is less than 10%; C: The number of peelings between the primer coating film and the metal base coating film or between the mild steel plate and the primer coating film is 10% or more.

[0142] Drying test

[0143] On a mild steel plate of 300mm×100mm×0.8mm, so that the dry film thickness becomes 30 m Each primer composition obtained in the above Examples and Comparative Examples was sprayed in the form of m, and then dried at 20° C. for 20 minutes. The resulting coating film was pressed with a finger and evaluated according to the following criteria.

[0144] S: There is no sticky feeling on the fingers and the coating film has no change at all; A: The fingers feel a little sticky, but the coating film does not change at all; B: The fingers feel sticky and some finger marks remain on the coating; C: The fingers feel noticeably sticky, and finger marks are clearly left on the coating film.

[0145] Water resistance test

[0146] The coated plate obtained in the above-mentioned finishing test was immersed in warm water at 40° C. for 10 days, and the coating film surface was observed.

[0147] S: Very good; A: Very slight swelling of the coating film was observed; B: The whole coating film was observed to swell; C: Abnormalities such as swelling, blistering, and whitening of the coating film were observed.

[0148] Water-based applicability test

[0149] On a mild steel plate of 300mm×100mm×0.8mm, so that the dry film thickness becomes 60 m m spray coating of each primer composition obtained in the above examples and comparative examples, and then drying at 20 ° C for 60 minutes. The dried coating film was polished with P400 sandpaper to a dry film thickness of 15 m "Retan WB Eco EVBase #400 Deep Black" (trade name, one-component water-based topcoat for automobile repair, manufactured by Kansai Paint Co., Ltd.) was air-sprayed on the uncured coating film at room temperature for 5 minutes after coating to a dry film thickness of 40 m. m"Retan PG Eco HX Clear Q Base" (trade name, two-component topcoat clear coating for automotive refinishing, manufactured by Kansai Paint Co., Ltd.) was air-sprayed in a 1 / 4-meter (m) format. After standing at room temperature for 10 minutes, the panels were heated in a hot air circulation drying oven at 60°C for 20 minutes to obtain test panels. The appearance of each test-coated panel was then observed from an oblique side (diagonal direction) and evaluated according to the following evaluation criteria.

[0150] S: Glossiness and coating smoothness are very good; A: Good gloss and coating smoothness; B: Glossiness and coating smoothness are slightly poor; C: Glossiness and coating surface smoothness are poor.

[0151] Plastic adhesion test

[0152] 2.5 parts of Superchlon 930S (chlorinated polyolefin, manufactured by Nippon Paper Industries, Ltd.) and 97.5 parts of n-butyl propionate were mixed to obtain a plastic additive. Five parts of the plastic additive were added to 100 parts each of the primer compositions (X-2), (X-4) to (X-7) prepared in Examples 2 and 4 to 7, and the mixture was mixed to obtain primer compositions (Y-2), (Y-4) to (Y-7) for plastic substrates.

[0153] On a 300mm×100mm×5mm polypropylene plate, the dry film thickness was 60 m m, respectively, sprayed the above-mentioned primer composition for plastic substrates and dried at 20° C. for 60 minutes. The dried coating film was polished with P400 sandpaper to a dry film thickness of 15 m "Retan WB Eco EV Base #400 Deep Black" (trade name, one-component water-based topcoat for automobile repair, manufactured by Kansai Paint Co., Ltd.) was air-sprayed in a manner of 100 m. After coating, the uncured coating was left to stand at room temperature for 5 minutes to a dry film thickness of 40 m. m "Retan PG Eco HX Clear Q Base" (trade name, two-component topcoat clear paint for automobile repair, manufactured by Kansai Paint Co., Ltd.) was air-sprayed in a m-type manner. After standing at room temperature for 10 minutes, it was heated at 60°C for 20 minutes in a hot air circulation drying oven to obtain a test plate.

[0154] A cross-cut adhesion test based on JIS K5600 was conducted on the test coated panels. Specifically, 100 lattice cuts were made in the coating film at 2 mm intervals in the vertical and horizontal directions, in a checkerboard pattern to match the texture of the material. A tape with an adhesive strength of 120 gf / 10 mm was then applied. The tape was then peeled off instantly, and the number of coating flakes remaining on the tape after peeling was measured. Evaluation was performed according to the following criteria.

[0155] A: There is no peeling between the base coating and the metal base coating, and between the polypropylene plate and the base coating; B: The peeling number between the base coating and the metal base coating, and between the polypropylene plate and the base coating is less than 10%; C: The number of peelings between the primer coating film and the metal base coating film, and between the polypropylene plate and the primer coating film is 10% or more.

Claims

1. A multi-component organic solvent-based primer composition, which is obtained by mixing a main agent component (I) and a curing agent component (II), wherein: The main agent component (I) comprises acrylic polyol (A), pigment composition (B) and organic solvent (C), and the curing agent component (II) comprises a polyisocyanate compound. The acrylic polyol (A) contained in the main agent component (I) comprises an acrylic polyol (A1) having a glass transition temperature of 40 to 70° C. and an acrylic polyol (A2) having a glass transition temperature of 0 to 30° C. The pigment composition (B) contained in the main agent component (I) contains barium sulfate and clay as a part of the pigment composition (B).

2. The primer composition according to claim 1, wherein The solid content ratio of the acrylic polyol (A1) having a glass transition temperature of 40 to 70° C. to the acrylic polyol (A2) having a glass transition temperature of 0 to 30° C. is 30 / 70 to 99 / 1 in terms of mass ratio.

3. The primer composition according to claim 1, wherein The content of the pigment composition (B) is in the range of 100 to 300 parts by mass based on 100 parts by mass of the solid content of the acrylic polyol (A).

4. The primer composition according to claim 1, wherein The SP value of the acrylic polyol (A) is 8.5 to 9.5 (cal / cm 3 ) 1 / 2 range.

5. The primer composition according to claim 1, wherein The main agent component (I) further comprises a surface conditioner having a nonionic hydrophilic group.

6. The primer composition according to claim 1, wherein The main agent component (I) further comprises a silane coupling agent.

7. A method for repairing a coating, comprising: The base coating composition according to any one of claims 1 to 6 is applied to the repaired part to be optionally coated with putty to form a 5 μ m~50 μ m base coating process; and A step of applying a colored coating composition on the base coating film.

8. The repair coating method according to claim 7, wherein: The colored coating composition is a water-based coating.

9. A method for repairing a coating, wherein: include: A process of applying a primer composition obtained by adding a chlorinated polyolefin to the primer composition according to any one of claims 1 to 6 to a portion to be repaired including a plastic surface.

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