JP5979766B2 - Multi-component organic solvent-based undercoating composition and repair coating method using the same - Google Patents

Description

  The present invention relates to an organic solvent-based primer coating composition particularly useful for repair coating of automobiles and the like, and a repair coating method using the same.

  In general, repair coating of automobile skins, etc., is performed by removing the old paint film at the damaged part or sanding, then applying a plating putty on the spot with a spatula, etc., drying and polishing the putty surface. Apply the resin putty with a spatula to cover the old paint film around the part, polish the putty surface after drying, then apply primer surfacer coating and top coating sequentially on this, etc. Consists of.

  The putty-primer surfacer painting process is a process to remove the distortion of the damaged part and prepare the car body to its original shape. The putty type is applied to shallow scratches such as dots and lines. In addition, since each coated surface is polished step by step using a plurality of water-resistant papers having different grain sizes, a great amount of labor and time are spent.

  Therefore, the present applicant can spray-coat a coating composition containing an acrylic resin having a specific weight average molecular weight, a specific amount of pigment, resin fine particles, a large amount of polyisocyanate compound, and a specific amount of curing catalyst. It is found that it has a thick film forming property that can conceal the defective part (paper eyes due to insufficient polishing, etc.), and it is proposed that the putty process and polishing work can be greatly simplified by using this as a primer surfacer did.

  By the way, the conventional automobile repair painting process is a three-coat two-bake in which after the primer surfacer coating, drying and polishing are performed, the color base coating is applied to the polished surface, and the resulting color base coating is dried after clear coating. It has become mainstream. In this case, the primer surfacer painting process is not only a painting process, but also a drying process and a polishing process, and thus a lot of work time is spent.

  Therefore, when a solvent-based or water-based color base is applied wet-on-wet after conventional primer surfacer coating, the final finish is not satisfactory, and primer surfacer adhesion strength is also difficult, There is a need for the development of an undercoating composition that does not affect the appearance of the overcoating of the next process or the performance as a repair coating even if the drying or polishing process is reduced or omitted.

JP 2002-173632 A

  An object of the present invention is to provide a primer coating composition capable of forming an undercoat film having moderate adhesion strength and excellent abrasiveness, and reducing the time required for the entire coating including the topcoat in the next step, and It is in providing the repair coating method using this.

  As a result of intensive studies on the above problems, the present inventors have determined that an acrylic resin having a specific structure as a composition obtained by combining a main ingredient component containing an acrylic polyol and a pigment and a curing agent component containing a polyisocyanate compound. As a result, it was found that an undercoat film excellent in adhesion strength to the top coat film and abrasiveness was obtained, and the present invention was achieved.

That is, the present invention
A multi-component organic solvent-based undercoating composition obtained by mixing a main component (I) and a curing agent component (II), wherein the main component (I) is a lactone-modified acrylic polyol (A), A pigment composition (B), an organic solvent (C), and an amide viscosity modifier, the curing agent component (II) contains a polyisocyanate compound, and the pigment composition (B) contained in the main agent component (I) Including talc and rust preventive pigment as a part of the component, talc content is 100 to 250 parts by mass based on 100 parts by mass of lactone-modified acrylic polyol (A) solid content, and content of rust preventive pigment is lactone The content of the pigment composition (B) is based on 100 parts by mass of the lactone-modified acrylic polyol (A) solid content, based on 100 parts by mass of the modified acrylic polyol (A) solid content. The present invention relates to an undercoat paint composition characterized by being in the range of 50 to 500 parts by mass, and a repair coating method using the undercoat paint composition for base coating.

  The undercoat composition of the present invention has an appropriate thickness, has excellent abrasiveness, and can form an undercoat film having high adhesion strength to the topcoat film. By applying a solvent-based or water-based top coating composition, it is possible to form a repair coating film having an excellent appearance with little influence of the base. It is also possible to wet-on-wet the base coating composition and the top coating composition to obtain a repaired coating with a natural appearance, greatly reducing the total work time and energy required for repair coating. It can be omitted.

  The undercoat coating composition of the present invention is a multi-component composition obtained by mixing the main component (I) and the curing agent component (II). Hereinafter, it demonstrates in order.

  First, the main component (I) will be described.

<Lactone modified acrylic polyol (A)>
In the present invention, an acrylic polyol that can be a polyurethane film-forming component together with a polyisocyanate compound described later is characterized by being lactone-modified.

  This is because the lactone modification improves the adhesion of the undercoat coating film formed by the undercoat paint composition of the present invention.

  As the lactone-modified acrylic polyol (A), for example, a copolymer of a polymerizable unsaturated monomer containing a lactone-modified hydroxyalkyl (meth) acrylate as an essential component and containing at least one (meth) acryloyl group-containing monomer. Can be.

  Lactone-modified hydroxyalkyl (meth) acrylate can be a reaction product of lactone and hydroxyalkyl (meth) acrylate, and examples thereof include compounds represented by the following general formula (1).

[Wherein, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 6 carbon atoms, and n represents 1 to 25. ].

  The lactone-modified hydroxyalkyl (meth) acrylate specifically includes “Placcel FA-1”, “Placcel FA-2”, “Placcel FA-2D”, “Placcel FA-3”, “Placcel FA-4”, “Placcel FA-5”, “Plaxel FM-1”, “Plaxel FM-2”, “Plaxel FM-2D”, “Plaxel FM-3”, “Plaxel FM-4”, “Plaxel FM-5” (any Can also be mentioned commercial products such as Daicel Chemical Industries, Ltd., trade name).

  The copolymerization ratio of the lactone-modified hydroxyalkyl (meth) acrylate is 1 to 50% by mass, preferably 5 to 30% by mass, based on the total polymerizable unsaturated monomer used in the production of the lactone-modified acrylic polyol (A). % From the viewpoint of adhesion to the top coat film formed from the coating composition of the present invention and abrasiveness.

  Examples of the (meth) acryloyl group-containing monomer copolymerized with the lactone-modified hydroxyalkyl (meth) acrylate include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth). Acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, etc. Chain or branched alkyl (meth) acrylate; Cyclohexyl (meth) acrylate, cycloaliphatic alkyl (meth) acrylate such as isobornyl (meth) acrylate; Aralkyl such as benzyl (meth) acrylate (Meth) acrylates; alkoxyalkyl (meth) acrylates such as 2-methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3- Hydroxypropyl (meth) acrylates such as hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate, and other hydroxyl group-containing (meth) acrylates not modified with lactone such as polyoxyethylene chain-containing (meth) acrylate having a hydroxyl group at the molecular end ) Acryloyl monomer; perfluoroalkyl (meth) acrylate; N, N-dialkylaminoalkyl (meth) acrylate such as N, N-diethylaminoethyl (meth) acrylate; (meth) acrylic 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, pentaerythritol di (meth) acrylate, pentaerythritol tetra ( (Meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethane di (meth) acrylate, 1,1,1-trishydroxymethylethanetri (meth) acrylate, 1 (Meth) acryloyl monomer having at least two polymerizable unsaturated groups in one molecule such as 1,1,1-trishydroxymethylpropane tri (meth) acrylate ;; (meth) acrylic acid; acetoacetoxyethyl (meth) Carbonyl group-containing (meth) acryloyl monomers such as acrylate and diacetone (meth) acrylamide; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4- Epoxy group-containing (meth) acryloyl monomers such as epoxycyclohexylethyl (meth) acrylate and 3,4-epoxycyclohexylpropyl (meth) acrylate; Isocyanato group-containing (meth) acrylates such as isocyanatoethyl (meth) acrylate Monomer; alkoxysilyl group-containing (meth) acryloyl monomer such as γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane; dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyloxypropyl (meth) acrylate And oxidatively curable group-containing (meth) acryloyl monomers such as dicyclopentenyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  Examples of other polymerizable unsaturated monomers that can be copolymerized other than (meth) acryloyl group-containing monomers include (meth) acrylonitrile; vinyl ester compounds such as vinyl acetate and vinyl propionate; styrene, α-methylstyrene. Vinyl aromatic compounds such as triallyl isocyanurate, diallyl terephthalate, divinylbenzene, etc., polyvinyl compounds having at least two polymerizable unsaturated groups in one molecule; maleic acid, crotonic acid, β-carboxyethyl acrylate, etc. Carboxyl group-containing polymerizable unsaturated monomers; hydroxyl group-containing polymerizable unsaturated monomers such as allyl alcohol; (meth) acrolein, formylstyrene, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, Vinyl butyl ketone ), Carbonyl group-containing polymerizable unsaturated monomers such as acetoacetoxyallyl ester; epoxy group-containing polymerizable unsaturated monomers such as allyl glycidyl ether; isocyanato group-containing polymerization such as m-isopropenyl-α, α-dimethylbenzyl isocyanate Unsaturated unsaturated monomers; alkoxysilyl group-containing polymerizable unsaturated monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; epoxy group-containing polymerizable unsaturated monomers or hydroxyl group-containing polymerizable unsaturated monomers and reaction products of unsaturated fatty acids Examples thereof include oxidatively curable group-containing polymerizable unsaturated monomers, etc., and these can be used alone or in combination of two or more.

  The lactone-modified acrylic polyol (A) has a weight average molecular weight of 5,000 to 80,000, preferably 6,000 to 70,000, and a solid content hydroxyl value of 200 mgKOH / g or less, preferably 50 to 150 mg. It is suitable that the solid content acid value is in the range of 1 to 30 mgKOH / g, preferably 5 to 15 mgKOH / g in the range of / KOH. This is because the adhesion of the formed coating film is improved.

  In this specification, the weight average molecular weight is a value obtained by converting the weight average molecular weight measured by gel permeation chromatograph (“HLC8120GPC” manufactured by Tosoh Corporation) based on the weight average molecular weight of polystyrene. Columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation, trade names) ), Mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 ml / min, detector: RI.

  The lactone-modified acrylic polyol (A) is suitably contained in an amount of 75% by mass or more, preferably 85% by mass or more in the resin solid content contained in the main component (I).

<Pigment composition (B)>
In the present invention, the pigment composition (B) contained in the main component (I) contains talc as an extender pigment.

  As the talc in the present invention, those known as extender pigments in the paint field and the like can be used, which may be synthetic products or natural products, and the surface is treated as necessary. Also good. Moreover, there is no restriction | limiting also in the shape and magnitude | size.

  The content of talc contained in the pigment composition (B) is 50 to 300 parts by mass, preferably 100 to 250 parts by mass, based on 100 parts by mass of the acrylic polyol (A) solid content contained in the main component (I). It is in the range of the part.

  In the present invention, the undercoating composition contains talc, and the abrasiveness of the undercoating film formed by the talc content being in this range is improved, and the topcoating of the next step is wet-on-wet Is also possible.

  The pigment composition (B) preferably contains a rust preventive pigment in addition to talc. Thereby, the water resistance of the undercoat coating film formed from the undercoat composition of the present invention and the adhesion to the substrate are improved.

  Examples of the anticorrosive pigment include zinc compounds such as zinc and zinc oxide; magnesium phosphate, magnesium phosphate / ammonium eutectoid, magnesium monohydrogen phosphate, magnesium dihydrogen phosphate, magnesium phosphate / calcium eutectoid , Magnesium phosphate / cobalt eutectoid, magnesium phosphate / nickel eutectoid, magnesium phosphite, magnesium phosphite / calcium eutectoid, calcium phosphate, calcium phosphite, calcium ammonium phosphate, calcium monohydrogen phosphate, phosphorus Calcium oxide dihydrogen phosphate, calcium phosphate phosphate, aluminum phosphate, aluminum hydrogen phosphate, aluminum tripolyphosphate, aluminum dihydrogen tripolyphosphate, magnesium tripolyphosphate, aluminum dihydrogen triphosphate Phosphoric metal salts such as treated with calcium, treated with magnesium tripolyphosphate dimagnesium oxide; silica, colloidal silica, metal ion exchanged silica; vanadium pentoxide, calcium vanadate, magnesium vanadate and ammonium metavanadate, manganese oxide And vanadium oxide, vanadium compounds such as calcium phosphate and vanadium oxide, etc .: aluminum molybdate, calcium molybdate, aluminum phosphomolybdate, cobalt hydroxide, etc. Two or more kinds can be used in combination.

  As the anticorrosive pigment, a zinc compound is suitable from the viewpoint of water resistance and adhesion to the substrate.

  The preferable content of the rust preventive pigment is in the range of 1 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the solid content of the lactone-modified acrylic polyol (A).

  Moreover, the said pigment composition (B) can contain well-known pigments, such as extender pigments other than talc, and a color pigment, as needed.

  Among these, other extender pigments include, for example, calcium carbonate, barium sulfate, barium carbonate, aluminum silicate, gypsum, clay, silica, white carbon, diatomaceous earth, magnesium carbonate, alumina white, gloss white, mica powder and the like. Can do.

  Examples of the color pigment 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 iron oxide, titanium yellow, monoazo yellow, Yellow pigments such as condensed azo yellow, azomethine yellow, bismuth vanadate, benzimidazolone, isoindolinone, isoindoline, quinophthalone, benzidine yellow, permanent yellow; orange pigments such as permanent orange; red iron oxide, naphthol AS azo red, Ansanthrone, Anthraquinonyl Red, Perylene Maroon, Quinacridone Red Pigment, Diketopyrrolopyrrole, Watching Red, Permanent Red, etc. Red Pigment; Cobalt Purple, Quinacridone Violet, Geo Purple pigments such as sajin violet; Blue pigments such as cobalt blue, phthalocyanine blue and selenium blue; Green pigments such as phthalocyanine green; Metallic pigments such as aluminum powder, bronze powder, copper powder, tin powder, iron phosphide and zinc powder; Examples thereof include pearlescent pigments such as metal oxide-coated mica powder and mica-like iron oxide, and these pigments can be used alone or in combination of two or more.

  In the present invention, as the content of the pigment composition (B), the pigment composition (B) is from 50 to 50 based on 100 parts by mass of the lactone-modified acrylic polyol (A) resin solid content contained in the main component (I). It is suitable from the viewpoint of the adhesion strength of the undercoat film and the finished appearance after top coating that it is in the range of 500 parts by mass, preferably 100 to 400 parts by mass.

<Organic solvent (C)>
In the present invention, examples of the organic solvent (C) include organic compounds having a molecular weight in the range of 58 to 220, particularly 72 to 200, and those known in the paint field can be used without limitation. For example, it is desirable to include at least one organic solvent selected from an ester organic solvent and a ketone organic solvent.

  Examples of such 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. , Diethylene glycol monoethyl ether acetate and the like, and examples of ketone organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl isoamyl ketone, diisobutyl ketone, methyl hexyl ketone, and isophorone. It can be used alone or in combination of two or more.

  The amount of at least one organic solvent selected from such ester organic solvents and ketone organic solvents is 5% by mass or more, particularly 20% by mass, based on the total organic solvent contained in the primer coating composition of the present invention. It is desirable to be above.

  In the present invention, other organic solvents other than the ester organic solvents and ketone organic solvents include n-butane, n-hexane, n-heptane, n-pentane, n-octane, n-nonane, n-decane, linear alkanes such as n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, 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-dimethylpentane, 2,2,3-trimethyl Pentane, 2,2,4-trimethylpentane, 3,4-diethylhexane, 2,6-dimethyloctane, 3,3-di Tyloctane, 3,5-dimethyloctane, 4,4-dimethyloctane, 3-ethyl-3-methylheptane, 2-methylnonane, 3-methylnonane, 4-methylnonane, 5-methylnonane, 2-methylundecane, 3-methylundecane Branched alkanes such as 2,2,4,6,6-pentamethylheptane; cyclopentane, t-decalin, cyclohexane, methylcyclohexane, ethylcyclohexane, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1 , 4-dimethylcyclohexane, propylcyclohexane, isopropylcyclohexane, 1,2-methylethylcyclohexane, 1,3-methylethylcyclohexane, 1,4-methylethylcyclohexane, 1,2,3-trimethylcyclohexane, 1,2 Aliphatic hydrocarbon organic solvents such as cyclic alkanes such as 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 monoisopropyl ether, ethylene glycol mono n-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 Ether organic solvents such as glycol monoethyl ether, dipropylene glycol mono n-propyl ether, dipropylene glycol monoisopropyl ether, methanol, isopropanol, tert-butanol, secondary butanol, isobutanol, n-butanol, 2-ethylhexanol, n-Octanol, Ben It can be exemplified an alcohol-based organic solvent such as alcohol.

  The organic solvent (C) can be blended as a polymerization solvent and a dilution solvent in the production of the lactone-modified acrylic polyol (A), or for dilution in the production of the main component (I).

<Main ingredient component (I)>
As the main component (I), in addition to the lactone-modified acrylic polyol (A), the pigment composition (B) and the organic solvent (C), a viscosity modifier, a curing catalyst, cellulose acetate butyrate and a modified product thereof, polyester Additives for paints such as resins for modifying other than lactone-modified acrylic polyol (A) such as resin, alkyd resin, polyurethane resin, pigment dispersant, surface conditioner, resin particles, and the like can be appropriately blended.

  Of these, conventionally known viscosity modifiers can be used, but amide viscosity modifiers are particularly preferred.

  By using an amide-based viscosity modifier, the storage stability of the main component (I) and the coating workability of the primer coating composition of the present invention are improved, and the adhesion strength to the top coating film of the primer coating composition Has the effect of improving.

  As such an amide-based viscosity modifier, those known in the paint field can be used without limitation, and the synthesis method, materials used, etc. are not particularly limited, and commercially available products can also be used.

  Specifically, fatty acid monoamides synthesized by dehydration of fatty acid ammonium salts or ammonolysis of fats and oils (esters); condensation reaction of fatty acid amide and formaldehyde, heat condensation reaction of monocarboxylic acid and diamine, or dibasic acid and monoamine Fatty acid diamide (bisamide) synthesized by heat condensation reaction with diamine; obtained by polycondensation of dibasic acid and diamine, polycondensation of diamine derivative and dibasic acid, dimerization of diamine and dibasic acid derivative or unsaturated fatty acid And fatty acid polyamides obtained by polycondensation of dimer acid or ring-opening polymerization of lactam.

  Such an amide viscosity modifier may be diluted with a diluent medium such as an organic solvent. In the present invention, the content of the active ingredient (component other than the dilution medium) of the amide-based viscosity modifier is 0.1 to 15 parts by mass based on 100 parts by mass of the lactone-modified acrylic polyol (A) solid content. , Preferably it is in the range of 0.5-8 parts by mass.

  Further, as the curing catalyst, a conventionally known urethanization catalyst can be applied without particular limitation. For example, bismuth nitrate, lead oleate, tin octylate, dibutyltin dilaurate, dibutyltin bis (acetylacetonate), dibutyltin diacetate, Examples thereof include metal compounds such as dibutyltin octanoate, dioctyltin dilaurate, dioctyltin dineodecanoate, titanium tetrachloride, dibutyltitanium dichloride, tetrabutyltitanate, iron trichloride, and zinc octylate, and tertiary amines.

  The curing catalyst may be contained in any of the main agent component (I), the curing agent component (II), and the polyol component (III) described later, but when contained in the main agent component (I), the content of the curing catalyst is contained. The amount is 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass based on 100 parts by mass of the solid content of the acrylic polyol (A), and the curability of the composition of the present invention and the main component ( It is suitable from the viewpoint of suppressing the increase in viscosity after mixing I) and curing agent component (II).

  The main ingredient component (I) can have a low viscosity relative to the solid content concentration, and can exhibit excellent coating workability. Specifically, the viscosity in the storage state (sealed can state) can be in the range of 75 to 140 KU, particularly 80 to 120 KU.

  In this specification, it is assumed that the viscosity of the sample adjusted to 25 ° C. is measured with a Stormer viscometer.

<Polyisocyanate compound (D)>
In the present invention, the polyisocyanate compound (D) is a polyisocyanate compound having two or more isocyanate groups in one molecule. Specific examples thereof include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, meta-tetramethylxylylene diisocyanate, tolylene diisocyanate, 4,4 ′. -Polyisocyanate compounds such as diphenylmethane diisocyanate and lysine diisocyanate, or adducts of these polyisocyanates with polyhydric alcohols, low molecular weight polyester resins or water, or cyclized polymers of each polyisocyanate as described above Furthermore, an isocyanate biuret body etc. are mentioned, These may be used 1 type and may be used in combination of 2 or more type.

<Curing agent component (II)>
In the present invention, the curing agent component (II) contains the polyisocyanate compound (D), and an organic solvent; paint additives such as a viscosity modifier, a curing catalyst, and a surface modifier are blended as necessary. can do.

<Polyol component (III)>
The undercoat coating composition of the present invention is obtained by mixing the main component (I) and the curing agent component (II) immediately before coating, and if necessary, the polyol component (III) may be further combined. it can.

  By constituting the undercoating composition with a multi-component system of the main component (I), the curing agent component (II) and the polyol component (III), the storage stability of each component is good and the undercoating composition of the present invention is used. Even if the undercoat paint film formation process with the composition and the top coat coloring paint composition coating process, which is the next process, are applied wet-on-wet, or the polishing process is omitted or shortened, a coating film with excellent finished appearance can be obtained. Has the effect of forming.

  In the present invention, as the polyol component (III), a polyol compound is essential, and other components are included as necessary. Examples of the polyol compound include acrylic polyol, polyester polyol, polyurethane polyol, cellulose acetate butyrate and Conventionally known polyol compounds such as modified products thereof can be mentioned, and these polyol compounds can be used alone or in combination of two or more.

  As the polyol compound, an acrylic polyol is suitable from the viewpoint of miscibility with the main component (I). The lactone-modified acrylic polyol (A) may be used as the acrylic polyol contained in the polyol component (III).

  In the present invention, the polyol component (III) is different from the main component (I) in that the blending amount of the pigment is less than 50 parts by mass based on 100 parts by mass of the polyol compound solid content. In the polyol component (III), the amount of the pigment based on 100 parts by mass of the polyol compound solid content is less than 20 parts by mass, preferably less than 0.5 parts by mass, or substantially contains the pigment. It is suitable from the viewpoint of the finished appearance in the wet-on-wet coating process.

  The solid content concentration of the polyol component (III) is generally adjusted to be within a range of 10 to 70% by mass, preferably 20 to 60% by mass.

  The polyol component (III) contains the curing catalyst from the viewpoint of undercoat / topcoat adhesion during wet-on-wet coating with the topcoat in the next step and curability of the formed undercoat. It is desirable.

  The content of the curing catalyst is 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the solid content of the polyol compound contained in the polyol component (III). Is suitable.

  Moreover, the said polyol component (III) can contain additives for coating materials, such as an organic solvent, a viscosity modifier, a pigment dispersant, a surface modifier, and a resin particle as needed.

  As an organic solvent, it can select from the compound illustrated by description of the said organic solvent (C) suitably, and can use it.

<Undercoat paint composition>
In the present invention, the main agent component (I) and the hardener component (II) are mixed with 0.8 equivalent of an isocyanate group in the hardener component (II) with respect to 1 equivalent of a hydroxyl group in the main agent component (I). It is suitable to mix | blend so that it may become a ratio of 4.0 equivalent, preferably 1.0-3.5 equivalent.

  Further, when the undercoat coating composition of the present invention is composed of the main agent component (I), the curing agent component (II) and the polyol component (III), it is contained in the main agent component (I) and the polyol component (III). It is suitable to blend so that the isocyanate group in the curing agent component (II) is 0.5 to 3.0 equivalent, preferably 0.7 to 2.5 with respect to 1 equivalent of the hydroxyl group.

  Further, when the undercoat composition of the present invention is a three-component system of component (I), component (II) and component (III), the mass of polyol component (III) based on 100 parts by mass of main component (I) Is in the range of 30 to 150 parts by weight, preferably 50 to 120 parts by weight.

  The composition of the present invention thus obtained is a two-component composition or a three-component composition in which each component is stored separately. In general, each component is mixed immediately before coating, and if necessary, a diluted thinner is used. The viscosity is adjusted before use.

  The present invention further provides a repair coating method using the above composition for base coating.

  The repair coating film applicable to the method of the present invention includes, for example, a coating film coated on an outer plate part of an automobile or a household electric appliance, and this may be an undercoating film or an intermediate coating film (may be omitted) ) And a top coat film in many cases. The coating film may be either a solid type or a metallic type. These coating films may be three-dimensional crosslinked cured coating films or non-crosslinked coating films.

  In the method of the present invention, first, a damaged portion of the coating film is scraped off, and sanding is performed around the damaged portion as necessary, and then degreased as necessary. The present composition can be directly applied to the degreased portion if it is a line scar or a scratch, etc., and depending on the damage, the composition of the present invention can be applied after filling the scraped portion with various putty. . The putty can be filled by a method known per se by using a spatula. Examples of the putty include conventionally known plating putty and resin putty, and examples thereof include nitrified cotton, acrylic resin, epoxy acrylate resin, unsaturated polyester resin, and urethane resin. When the putty is applied, it is preferable to dry the putty and then polish the putty surface. However, since the composition of the present invention has a good base concealing property, the polished surface may be rough.

  For the coating of the composition of the present invention, a conventionally known coating method can be adopted, and spray coating is particularly suitable. The coating film thickness is in the range of 50 to 500 μm in terms of dry film thickness, and thick film coating is possible.

  Drying conditions are, for example, 5 to 40 ° C., preferably 10 to 30 ° C., and can be performed for 20 to 120 minutes, particularly 30 to 90 minutes.

  According to the present invention, even if the coating formed by the undercoat coating composition is uncured and overcoating in the next step, it has the advantage of having little influence on the finished appearance of the topcoat, It does not exclude drying and polishing of the undercoat film.

  The top coat may be a conventionally known coating such as a one-coat finish using only a colored base paint formed by blending a metallic pigment and / or a colored pigment, or a two-coat finish using the colored base paint and a clear paint. Can be mentioned.

  As the colored base paint, organic solvent-based and water-based top-coat paints that are usually used for repair can be used without any particular restrictions, and they are applied by known coating means such as spray painting, electrostatic painting, brush painting, roller painting, etc. be able to.

  In the case where the colored base paint is applied a plurality of times, steps such as flash-off (the coated film is allowed to stand at room temperature), air blowing, preheating, etc. may be provided between the respective coatings as necessary.

  Drying after the completion of the application of the colored base paint is not particularly limited, and may be in an uncured state when the top clear is reapplied. In general, it is preferable to dry for 5 to 60 minutes, for example, at a temperature of 20 to 100 ° C. The film thickness can be appropriately adjusted according to the state of the surface to be coated, but generally a dry film thickness of 5 to 100 μm, particularly 10 to 60 μm is suitable.

  As the top clear coating, conventionally known ones can be used without any particular limitation. For example, acrylic resin or fluorine resin containing a crosslinkable functional group such as a hydroxyl group is the main agent, and block polyisocyanate, polyisocyanate, melamine resin, or the like is a curing agent. Curable paints contained as lacquer paints mainly composed of cellulose acetate butyrate modified acrylic resin, etc. can be suitably used, and if necessary, pigments, fiber derivatives, additive resins, UV absorbers, It can contain paint additives such as a light stabilizer, a surface conditioner, and a curing catalyst.

  The top clear coating is preferably dried at a temperature of 20 to 100 ° C., preferably 40 to 100 ° C., for 5 to 60 minutes. The film thickness can be appropriately adjusted according to the state of the surface to be coated, but generally a dry film thickness of 5 to 100 μm, particularly 10 to 60 μm is suitable.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples. In the following examples, “part” and “%” mean “part by mass” and “% by mass”, respectively.

<Manufacture of two-component undercoat coating composition>
Example 1
30 parts of acrylic resin solution (Note 1) with a solid content of 55%, 6 parts of butyl acetate, 4 parts of methyl isobutyl ketone, 1.5 parts of pigment dispersant, 8.2 parts of titanium white, 30 parts of talc, 11 parts of barium sulfate , Zinc oxide 5.5 parts, dibutyltin dilaurate 0.1 part, amide type thickener (fatty acid amide, amide type viscosity modifier, active ingredient 20%) 0.8 parts in order, mixed and stirred, 30 Dispersion treatment was performed for a minute to obtain a main ingredient component. A polyisocyanate compound (“Sumidule N3390EA”, trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) as a curing agent was mixed with the main ingredient component immediately before use to obtain an undercoat paint composition (A-1).

(Note 1) Acrylic resin solution (1)
A reaction vessel was charged with 52 parts of butyl acetate, heated to 110 ° C. with stirring, 15 parts of styrene, 10 parts of methyl methacrylate, 10 parts of n-butyl methacrylate, 20 parts of t-butyl methacrylate, 2-methacrylic acid 2- 19 parts of ethylhexyl, 15 parts of 2-hydroxyethyl methacrylate, Plaxel FA-2D (trade name, manufactured by Daicel Chemical Industries, a reaction product of caprolactone and hydroxyethyl acrylate): 10 parts, a monomer comprising 1 part of acrylic acid and a polymerization initiator The monomer mixture was added dropwise at a constant rate at 110 ° C. or lower using a dropping pump over 3 hours. After completion of dropping, the temperature was kept at 110 ° C. for 60 minutes and stirring was continued. Thereafter, a solution prepared by dissolving 0.5 part of azobisisobutyronitrile in 7 parts of butyl acetate as an additional catalyst was dropped at a constant rate over 60 minutes. And after completion | finish of dripping, it hold | maintained at 110 degreeC for 60 minutes, and reaction was complete | finished. The obtained hydroxyl group-containing acrylic resin solution was a uniform yellow transparent solution with a nonvolatile content of 55%, and the weight average molecular weight of the resin was 14000 and the hydroxyl value was 81 mgKOH / g.

(Note 2) Acrylic resin solution (2)
A reaction vessel was charged with 52 parts of butyl acetate, heated to 110 ° C. with stirring, 10 parts of styrene, 10 parts of methyl methacrylate, 5 parts of n-butyl methacrylate, 60 parts of i-butyl methacrylate, 1 part of methacrylic acid, 2 -A monomer mixture consisting of 14 parts of hydroxyethyl methacrylate and 2.3 parts of azobisisobutyronitrile and a monomer mixture of the polymerization initiator was added dropwise at a constant rate over 3 hours using a dropping pump at 110 ° C or lower. After completion of dropping, the temperature was kept at 110 ° C. for 60 minutes and stirring was continued. Thereafter, a solution prepared by dissolving 0.5 part of azobisisobutyronitrile in 7 parts of butyl acetate as an additional catalyst was dropped at a constant rate over 60 minutes. And after completion | finish of dripping, it hold | maintained at 110 degreeC for 60 minutes, and reaction was complete | finished. The obtained hydroxyl group-containing acrylic resin solution was a uniform yellow transparent solution having a nonvolatile content of 55%, and the weight average molecular weight of the resin was 18000 and the hydroxyl value was 60 mgKOH / g.

Examples 2-6 and Comparative Examples 9-13
In Example 1 above, the undercoat paint compositions (A-2) to (A-6) and (A-9) to (A-) were used in the same manner as in Example 1 except that the composition shown in Table 1 was used. 13) was obtained.

<Manufacture of three-component undercoat coating composition>
Examples 7-8
In the formulation shown in Table 1, the main component, the curing agent component, and the clear composition were mixed immediately before use to obtain the respective undercoat coating compositions (A-7) and (A-8).

(Note 3) Clear composition (III)
In a stirring and mixing container, 40 parts of an acrylic resin solution (Note 1), 59.7 parts of butyl acetate, 0.2 part of dibutyltin dilaurate, and 0.1 part of a surface conditioner are blended and stirred to obtain a clear composition. It was.

<Performance test>
(*) “LUC Poly Putty” (unsaturated polyester putty, manufactured by Kansai Paint Co., Ltd.) was placed on a mild steel plate having a finished appearance of 300 × 100 × 0.8 mm with a spatula to a thickness of about 2 mm, and 60 ° C. at 60 ° C. After drying for a minute, the coated surface is polished so that the surface is smoothed with P120 air sharpening paper, and then each primer coating composition obtained in Examples and Comparative Examples on the coated surface is used as a primer surfacer. Prepared to be 50% solid content when diluted with diluted thinner, spray-coated to a dry film thickness of about 50 μm, and then allowed to stand at 20 ° C. for 10 minutes. # 202 Sun Metallic Base (trade name, top coating metallic paint for repairing automobiles, manufactured by Kansai Paint Co., Ltd.) was applied by air spray to a dry film thickness of 15 μm. On the uncured coating film left at room temperature for 5 minutes after coating, lettan PG Eco HX (Q) clear (trade name, two-pack top clear paint for automobile repair, manufactured by Kansai Paint Co., Ltd.) as a dry film thickness of 40 μm It was painted with air spray. After leaving at room temperature for 10 minutes, it was heated at 60 ° C. for 20 minutes using a hot-air circulating drying oven to obtain a test plate. Thereafter, the appearance of each test coated plate was observed from the scuffing direction (oblique direction) and evaluated according to the following evaluation criteria.
A: Glossiness and smoothness of the coating surface are very good, and neither suction nor prasuff marks are observed.
○: Glossy feeling and smoothness of the coating surface are good, and neither suction nor prasaf marks are observed. △: Glossy feeling or smoothness of the coating surface is slightly poor, and neither suction nor prasaf marks are observed. ,
X: The glossiness and the smoothness of the coating surface are poor, and either suction or prassaf marks are observed.

(*) Adhesion test Each of the undercoat paint compositions obtained in the above Examples and Comparative Examples was spray-coated on a 300 × 100 × 0.8 mm mild steel plate so that the dry film thickness was 60 μm, and then 20 ° C. , Air spray so that the dry film thickness is 15 μm on the cured coating film dried for 60 minutes, lettan PG Hybrid Eco # 202 Sun Metallic Base (product name, one-pack type automotive coating top coating, manufactured by Kansai Paint Co., Ltd.) Painted with. On the uncured coating film left at room temperature for 5 minutes after coating, lettan PG Eco HX (Q) clear (trade name, two-pack top clear paint for automobile repair, manufactured by Kansai Paint Co., Ltd.) as a dry film thickness of 40 μm It was painted with air spray. After leaving at room temperature for 10 minutes, it was heated at 60 ° C. for 20 minutes using a hot-air circulating drying oven to obtain a test plate. A cross cut test based on JIS K5600 was performed on this test coated plate. Specifically, 100 cuts reaching the material in a grid pattern at intervals of 2 mm in the vertical and horizontal directions are put on the coating film, and an adhesive tape having an adhesion force (120 gf / 10 mm) is applied. And this adhesive tape was peeled off instantaneously, the quantity of the coating film piece which peeled and adhered to the adhesive tape was investigated, and the following reference | standard evaluated.
○: No peeling between the primer coating and the metallic base coating,
Δ: Less than 10% peeling between the undercoat coating and the metallic base coating
X: 10% or more of peeling between the undercoat coating film and the metallic base coating film.

(*) Polishing feeling was evaluated when the surface of the primer surfacer at the time of preparing each test coating plate obtained with a polished finish appearance was polished with P600 paper.
A: Very good,
○: Good,
Δ: Slightly entangled,
X: There is considerable entanglement.
(*) Sagging resistance An article with 21 punch holes with a diameter of 5 mm in a line of 3 cm from the end on the long side of a 22 × 45 cm mild steel plate in a line at intervals of 2 cm. The coating composition for each undercoat was applied with a film thickness gradient in the longitudinal direction under the condition of 25 ° C., and the temperature of the coating plate was kept at 60 ° C. with the coated plate standing almost vertically. Then, it was forcibly dried for 20 minutes to obtain a test coated plate for a sagging resistance test. By examining the position where the sagging of the 2 mm coating film is observed from the lower end of the punch hole of each test coating plate obtained, and measuring the film thickness (sag limit film thickness (μm)) at this position, Evaluation was performed. The larger the sagging limit film thickness, the better the sagging resistance.
A: Sagging limit film thickness is 200 μm or more,
◯: Sagging limit film thickness is 150 μm or more and less than 200 μm,
Δ: Sagging limit film thickness is 100 μm or more and less than 150 μm,
X: Sagging limit film thickness is less than 100 μm.

Claims (7)

A multi-component organic solvent-based undercoating composition obtained by mixing a main component (I) and a curing agent component (II), wherein the main component (I) is a lactone-modified acrylic polyol (A), A pigment composition (B), an organic solvent (C), and an amide viscosity modifier, the curing agent component (II) contains a polyisocyanate compound, and the pigment composition (B) contained in the main agent component (I) Including talc and rust preventive pigment as a part of the component, talc content is 100 to 250 parts by mass based on 100 parts by mass of lactone-modified acrylic polyol (A) solid content, and content of rust preventive pigment is lactone The content of the pigment composition (B) is based on 100 parts by mass of the lactone-modified acrylic polyol (A) solid content, based on 100 parts by mass of the modified acrylic polyol (A) solid content. An undercoat paint composition characterized by being in the range of 50 to 500 parts by mass. The undercoat paint composition according to claim 1, wherein the amount of the active ingredient of the amide viscosity modifier is in the range of 0.1 to 15 parts by mass based on 100 parts by mass of the acrylic polyol (A) solid content. In addition to the main component (I) and the curing agent component (II), the polyol component (III) is a multi-component system further comprising the polyol component (III) containing the polyol compound, and the content of the pigment being polyol. The undercoat paint composition according to claim 1 or 2, which is less than 50 parts by mass based on 100 parts by mass of the compound solids or substantially free of pigment. The undercoating composition according to claim 3, wherein the polyol component (III) comprises a polyol compound and a curing catalyst. A repair coating method using the undercoat paint composition according to any one of claims 1 to 4 for undercoating. The undercoat paint composition according to any one of claims 1 to 4 is applied to a repair site that may be putty-coated, and the topcoat colored paint is applied in a state where the coating film of the undercoat paint composition is uncured. A repair coating method comprising a step of coating a composition. The undercoat paint composition according to any one of claims 1 to 4 is applied to a repair site that may be putty-coated, and the topcoat colored paint is applied in a state where the coating film of the undercoat paint composition is uncured. A repair coating method comprising a step of applying a composition, applying a top clear paint in an uncured state of the top coat coloring paint composition, and drying.