JP2005206622A - Coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition which has good storage stability and is reduced in the amount of organic solvents without deteriorating coating film performances such as adhesion and water resistance. <P>SOLUTION: The coating composition comprises an acrylic resin (A), a cellulose derivative (B) and a non-aqueous polymer fine particle dispersion (C), where the non-aqueous polymer fine particle dispersion (C) is obtained by copolymerizing vinyl monomers (b) in the presence of a macromonomer (a) having a structure represented by formula (1) at its molecular end, obtained by radical-polymerizing ethylenically unsaturated monomers in the presence of 2,4-diphenyl-4-methyl-1-pentene, in an organic solvent which dissolves the macromonomer (a) and the vinyl monomers (b) but does not substantially dissolve a polymer formed from the vinyl monomers (b). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coating composition containing a specific non-aqueous polymer fine particle dispersion, a coating finishing method using the coating composition, and a coated article.

  Conventionally, acrylic lacquers, acrylic urethane paints, aminoacrylic resin paints, etc. have been used for repairing automobiles, painting and repairing industrial machines, buildings, structures, furniture (including steel), etc., especially automobiles. In the field of repair coatings, solid finish coating and metallic finish coating mainly using acrylic lacquer, acrylic urethane paint, etc. are performed from the viewpoint of drying at room temperature. In recent years, metallic base paints containing glitter pigments and metallic finish paints that are repeatedly applied with clear paints have become the mainstream, and as a base coat, it is a one-pack type from the viewpoint of workability and convenience. A lacquer type paint is used.

  On the other hand, in recent years, there has been a strong demand for reducing the amount of organic solvent in paints due to the problem of environmental pollution. As a method for reducing the amount of organic solvent in the paint, for example, there is a method of reducing the viscosity by lowering the molecular weight of the acrylic resin as the base resin, but when used as a lacquer paint, the adhesion to the old paint film, etc. There is a problem that the coating performance such as water resistance is deteriorated. As a method for reducing the amount of the organic solvent in the paint without deteriorating the coating film performance, there is a method of adding a non-aqueous resin fine particle dispersion (NAD) to the solvent-type paint. A manufacturing method is disclosed. These conventional non-aqueous resin fine particle dispersions are generally low-polar monomers having a long-chain alkyl group such as a 12-hydroxystearic acid self-condensate (see Patent Document 2), 2-ethylhexyl acrylate, or lauryl methacrylate as a dispersion stabilizer. Therefore, there is a problem that the miscibility with a highly polar resin having many functional groups such as hydroxyl groups is poor.

Japanese Patent Laid-Open No. 49-30434

Japanese Patent Laid-Open No. 3-126770

  In recent years, in order to reduce the amount of organic solvent in the paint, the base resin used in the paint has been lowered in molecular weight, and accordingly, the amount of functional groups contained in the base resin has been increased to ensure the curability of the paint. . In particular, a resin having a relatively high polarity is used for the base coat resin for the purpose of preventing deterioration of the finished appearance (occurrence of mottling unevenness) due to a mixed layer during clear coat application. Development of a lacquer type paint containing NAD that is miscible with these highly polar resins is desired.

  An object of the present invention is to provide a coating composition having good storage stability and capable of reducing the amount of organic solvent in the coating without reducing coating performance such as adhesion and water resistance. .

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a non-aqueous polymer fine particle dispersion obtained by copolymerizing a vinyl monomer in the presence of a specific macromonomer, and the polymer The amount of organic solvent in the paint can be reduced without degrading the coating film performance by blending the fine particle dispersion obtained by impregnating the coalesced fine particles with the polyisocyanate compound and the cellulose derivative in the acrylic resin. The present inventors have found that a coating composition that can be obtained is obtained, and have completed the present invention.

  Thus, the present invention provides a coating composition containing the acrylic resin (A), the cellulose derivative (B), and the non-aqueous polymer fine particle dispersion (C), wherein the non-aqueous polymer fine particle dispersion (C) is A macromonomer having a structure represented by the following formula (1) at the molecular end obtained by radical polymerization of an ethylenically unsaturated monomer in the presence of 2,4-diphenyl-4-methyl-1-pentene ( In the presence of a), the vinyl monomer (b) is dissolved in the macromonomer (a) and the vinyl monomer (b), but the polymer is formed from the vinyl monomer (b). Is a coating composition obtained by copolymerization in an organic solvent that does not substantially dissolve, and is applied to the substrate surface as a base coat paint, and then a top clear paint is applied. Finishing method and coating finish About coated article obtainable by the lower way.

  According to the coating composition of the present invention, by including a specific non-aqueous polymer fine particle dispersion, the coating performance such as adhesion and water resistance can be maintained without deteriorating storage stability, The amount of organic solvent can be reduced. The coating composition of the present invention is useful for automobiles and industrial applications, and particularly useful as a repair coating for automobiles and the like.

  In the present invention, the acrylic resin (A) is usually a copolymer of an ethylenically unsaturated monomer containing an ester of acrylic acid or methacrylic acid, and can be dispersed or dissolved in an organic solvent in the paint to form a film. It is a resin having a function.

  Examples of the ethylenically unsaturated monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate (n-, i-, tert-), 2-ethylhexyl acrylate, N-octyl acrylate, hexyl acrylate, cyclohexyl acrylate, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate (n-, i-, tert-), 2-ethylhexyl methacrylate, n-octyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxy methacrylate Acrylic esters or methacrylic esters such as chill, ethoxybutyl acrylate, ethoxybutyl methacrylate; aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene; acrylic acid, methacrylic acid, etc. Carboxyl group-containing polymerizable unsaturated monomers; epoxy group-containing polymerizable unsaturated monomers such as glycidyl acrylate and glycidyl methacrylate; isocyanate groups such as isocyanatoethyl methacrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate Containing polymerizable unsaturated monomer; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate Hydroxyl group-containing polymerizable unsaturated monomers such as vinylate and 4-hydroxybutyl methacrylate; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl chloride , Vinyl halides such as vinylidene chloride and vinyl fluoride; amide unsaturated compounds such as acrylamide, methacrylamide, diacetone acrylamide, diacetone methacrylamide, N-methylol acrylamide and N-butoxymethyl acrylamide; vinyltrimethoxysilane And silyl group-containing unsaturated compounds such as 3- (trimethoxysilyl) propyl methacrylate, and the like can be used alone or in combination of two or more.

  The polymerization method for obtaining a copolymer by polymerizing an ethylenically unsaturated monomer containing the above acrylic acid or methacrylic acid ester is not particularly limited, and is a polymerization method known per se, such as radical polymerization. In the presence of an initiator, a solution polymerization method can be suitably used, such as a bulk polymerization method, a solution polymerization method, and a bulk-suspension two-stage polymerization method in which suspension polymerization is performed after bulk polymerization.

  The acrylic resin (A) obtained as described above has a weight average molecular weight of 10,000 to 100,000, preferably 20,000 to 60,000. From the viewpoints of finishing properties such as water resistance, water resistance, and smoothness of the coating film. In addition, the acrylic resin (A) has a glass transition temperature (Tg) of −10 to 80 ° C., preferably 10 to 60 ° C., from the viewpoint of drying properties and adhesion of the resulting coating film. In the present specification, the weight average molecular weight is a value obtained by converting the molecular weight measured by gel permeation chromatography based on the molecular weight of polystyrene, and the glass transition temperature (° C.) can be calculated by the following formula. it can.

1 / Tg (° K) = (W1 / T1) + (W2 / T2) +
Tg (° C.) = Tg (° K) -273
In each formula, W1, W2,... Represent the respective weight percentages of the monomers used for copolymerization, and T1, T2,... Represent the Tg (° K) of the monomer homopolymer. T1, T2,... Are values according to Polymer Hand Book (Second Edition, edited by J. Brandup / E.H. Immergut). The glass transition temperature (° C.) when the Tg of the homopolymer of the monomer is not clear is a static glass transition temperature, for example, using a differential scanning calorimeter “DSC-50Q type” (trade name, manufactured by Shimadzu Corporation). Take a sample in a measuring cup, remove the solvent completely by vacuum suction, measure the change in heat in the range of -100 ° C to + 100 ° C at a rate of 3 ° C / min. The change point of was the static glass transition temperature.

  The content (solid content) of the acrylic resin (A) is 10 to 85% by weight, preferably 20 to 60% by weight, based on the total resin solid content in the paint, etc. From the point of view is desirable. The acrylic resin (A) is preferably compatible with the later-described cellulose derivative (B) from the viewpoint of the storage stability of the paint and the appearance of the coating film.

  In the present invention, the cellulose derivative (B) is usually obtained by esterifying the hydroxyl group of cellulose with an acid such as fatty acid or nitric acid, such as nitrocellulose, cellulose acetate butyrate, cellulose acetate, cellulose acetate propionate, etc. Is mentioned. Among these, cellulose acetate butyrate can be preferably used.

  Cellulose acetate butyrate is a cellulose derivative obtained by further butyl esterifying a partially acetylated product of cellulose, preferably having an acetyl group content of generally 1 to 30% by weight and a butyl group content. Is generally 16 to 60% by weight. Specifically, for example, “CAB-381-0.5”, “CAB-381-0.1”, “CAB-381-2.0”, “CAB-551-0.2” (all in US -Stoma Kodak Co., Ltd. product name).

  The content (solid content) of the cellulose derivative (B) is 5 to 50% by weight, preferably 10 to 40% by weight, based on the total resin solid content in the paint. It is desirable from the viewpoint of properties and water resistance. Further, when the composition of the present invention contains a bright pigment such as an aluminum paste, if the content of the cellulose derivative (B) is small, unevenness due to a decrease in the orientation of aluminum tends to occur.

  The non-aqueous polymer fine particle dispersion (C) used in the present invention comprises a vinyl monomer (b), a macro monomer (a) and a vinyl monomer (in the presence of a specific macro monomer (a). Although b) dissolves, the polymer formed from the vinyl monomer (b) is obtained by copolymerization in an organic solvent that does not substantially dissolve.

  The macromonomer (a) is obtained by radical polymerization of an ethylenically unsaturated monomer in the presence of 2,4-diphenyl-4-methyl-1-pentene.

  2,4-diphenyl-4-methyl-1-pentene is an addition-cleavage type chain transfer agent that is also abbreviated as α-methylstyrene dimer, and the polymerizable unsaturated monomer is converted into 2,4-diphenyl-4-methyl. Chain transfer polymerization can be performed by a solution polymerization method or the like in an organic solvent in the presence of -1-pentene and a radical polymerization initiator. The resulting macromonomer has a structure represented by the following formula (1) at the molecular end.

  The amount of 2,4-diphenyl-4-methyl-1-pentene is not particularly limited, but is usually 1 to 50 weights based on 100 parts by weight of the total amount of polymerizable unsaturated monomers. Part, preferably in the range of 5 to 30 parts by weight.

  Examples of the polymerizable unsaturated monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate (n-, i-, tert-), and 2-ethylhexyl acrylate. , N-octyl acrylate, hexyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate (n-, i-, tert-), methacrylic acid 2 -Ethylhexyl, n-octyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxy methacrylate Esterified product of acrylic acid or methacrylic acid such as butyl and monoalcohol having 1 to 9 carbon atoms; n-decyl methacrylate, lauryl methacrylate, cetyl methacrylate, stearyl methacrylate, behenyl methacrylate, n-decyl acrylate, C10 or more carbon atoms at the molecular ends of lauryl acrylate, cetyl acrylate, stearyl acrylate, behenyl acrylate, Blemmer DSMA, SLMA, PMA, VMA-70, SLA (above, manufactured by NOF Corporation) Long-chain acrylic monomers having alkyl groups; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatic acid; vinyl cyanides such as acrylonitrile and methacrylonitrile; halogens such as vinyl chloride, vinylidene chloride and vinyl fluoride Vinyl chlorides Amide unsaturated compounds such as acrylamide, methacrylamide, diacetone acrylamide, diacetone methacrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide; silyl groups such as vinyltrimethoxysilane and 3-trimethoxysilylpropyl methacrylate Unsaturated compounds; aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene; carboxyl-containing polymerizable unsaturated monomers such as acrylic acid and methacrylic acid; glycidyl acrylate, glycidyl methacrylate, etc. Epoxy group-containing polymerizable unsaturated monomers: isocyanate group-containing polymerizable unsaturated monomers such as isocyanatoethyl methacrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate List hydroxyl group-containing polymerizable unsaturated monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, etc. Can do. These can be used alone or in combination of two or more.

  Examples of the radical polymerization initiator include organic peroxide polymerization initiators such as benzoyl peroxide, 2,2′-azobisisobutyronitrile, 1,1-azobis (cyclohexane-1-carbonitrile), and the like. And azo polymerization initiators.

  As the polymerization method by the solution polymerization method, for example, a polymerizable unsaturated monomer, a chain transfer agent 2,4-diphenyl-4-methyl-1-pentene and a radical polymerization initiator are dissolved in an organic solvent or A method of polymerizing by dispersing and heating usually at a temperature of about 0 ° C. to 200 ° C. with stirring for about 1 to 24 hours can be mentioned.

  Examples of the organic solvent include hydrocarbon solvents such as heptane, toluene, xylene, octane and mineral spirit; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, and diethylene glycol monobutyl ether acetate; Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol, isobutanol; n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene Ether type such as glycol monoethyl ether; Swazol 310, Swazol 1000, Swazol 1500 (all are cost And aromatic petroleum solvents such as SHELLSOL A (Shellsol A, manufactured by Shell Chemical Co., Ltd.). These organic solvents can be used alone or in combination of two or more.

  The weight average molecular weight of the macromonomer (a) is preferably in the range of 1,000 to 40,000, particularly 2,000 to 20,000, from the viewpoint of production stability of the polymer fine particle dispersion.

  Further, it is preferable that 70% by mole or more, preferably 80% by mole or more of the polymerizable unsaturated monomer constituting the macromonomer (a) is an ethylenically unsaturated monomer having a methacryloyl group. It is suitable for avoiding problems such as generation of clumps during liquid production.

  In the presence of the macromonomer (a), the vinyl monomer (b) is dissolved in the macromonomer (a) and the vinyl monomer (b), but is formed from the vinyl monomer (b). A polymer fine particle dispersion can be obtained by copolymerizing the polymer in an organic solvent that does not substantially dissolve. Although there is no restriction | limiting in particular in a vinyl-type monomer (b), When using for the manufacture of the below-mentioned non-aqueous polyurethane fine particle dispersion, a hydroxyl-containing vinyl-type monomer is required.

  Examples of the vinyl monomer (b) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and 4-hydroxybutyl methacrylate. C2-C8 hydroxyalkyl ester of acrylic acid or methacrylic acid; monoester of polyether polyol such as polyethylene glycol, polypropylene glycol or polybutylene glycol and unsaturated carboxylic acid such as acrylic acid or methacrylic acid, PLACEL FA- 2D (Daicel Chemical Industries, trade name, polycaprolactone-modified acrylate), PLACEL FM-3 (Daicel Chemical Industries, trade name, polycaprolactone-modified meta) And a hydroxyl group-containing vinyl monomer such as acrylate.

  Further, examples of the vinyl monomer (b) include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate (n-, i-, tert-), 2-acrylic acid 2- Ethylhexyl, n-octyl acrylate, hexyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate (n-, i-, tert-), methacrylic acid 2-ethylhexyl, n-octyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, methacrylate Esterified product of acrylic acid or methacrylic acid such as xylbutyl and monoalcohol having 1 to 9 carbon atoms; n-decyl methacrylate, lauryl methacrylate, cetyl methacrylate, stearyl methacrylate, behenyl methacrylate, n-decyl acrylate, C10 or more carbon atoms at the molecular ends of lauryl acrylate, cetyl acrylate, stearyl acrylate, behenyl acrylate, Blemmer DSMA, SLMA, PMA, VMA-70, SLA (above, manufactured by NOF Corporation) Long-chain acrylic monomers having alkyl groups; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatic acid; vinyl cyanides such as acrylonitrile and methacrylonitrile; halogens such as vinyl chloride, vinylidene chloride and vinyl fluoride Vinyl chloride Amide unsaturated compounds such as acrylamide, methacrylamide, diacetone acrylamide, diacetone methacrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide; silyl such as vinyltrimethoxysilane and 3-trimethoxysilylpropyl methacrylate Group-containing unsaturated compounds; aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, and α-chlorostyrene; carboxyl-containing polymerizable unsaturated monomers such as acrylic acid and methacrylic acid; glycidyl acrylate, glycidyl Examples thereof include an epoxy group-containing polymerizable unsaturated monomer such as methacrylate. These can be used alone or in combination of two or more.

  The organic liquid used as the dispersion medium when producing the polymer fine particle dispersion does not substantially dissolve the generated dispersion polymer particles, but the macromonomer (a) and the vinyl monomer (b) Is a good solvent and is preferably an organic liquid that is substantially immiscible with water. Preferable specific examples of such organic liquid include hexane, heptane, octane, mineral spirit, toluene, xylene, butyl acetate and the like, and these can be used alone or in combination.

  The copolymerization of the vinyl monomer (b) in the organic liquid in the presence of the macromonomer (a) is a method known per se (for example, the method described in JP-A-57-177068). Examples of radical polymerization initiators include organic peroxide polymerization initiators such as benzoyl peroxide, 2,2′-azobisisobutyronitrile, 1,1-azobis (cyclohexane -1-carbonitrile) and the like. As the reaction temperature during polymerization, a temperature in the range of 60 to 160 ° C. can be generally used, and the reaction is usually completed in 4 to 8 hours. be able to.

  In the present invention, the polymer fine particle dispersion obtained as described above can be used as the non-aqueous polymer fine particle dispersion (C), and the polyisocyanate compound (c) is added to the polymer fine particle dispersion obtained as described above. A non-aqueous polyurethane fine particle dispersion obtained by adding and impregnating the polyisocyanate compound (c) into the polymer fine particles and reacting the hydroxyl groups in the polymer fine particles with the isocyanate groups in the polyisocyanate compound (c) Can be used as the non-aqueous polymer fine particle dispersion (C).

  The polyisocyanate compound (c) has two or more isocyanate groups in one molecule. Examples of the polyisocyanate compound include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4 (or 2,6) -diisocyanate, Cyclic aliphatic diisocyanates such as 4,4′-methylenebis (cyclohexyl isocyanate) and 1,3-di (isocyanatomethyl) cyclohexane; Aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate and diphenylmethane diisocyanate; An organic polyisocyanate itself, such as a polyisocyanate having a valence of 3 or more, or each of these Machine polyisocyanate and a polyhydric alcohol, an adduct of low molecular weight polyester resin or water, etc., or cyclic polymer of the organic diisocyanate comrades such described above (e.g., isocyanurates), and the like biuret type adducts. These may be used alone or in combination of two or more.

  The polyisocyanate compound (c) is used in an amount of 0.2 to 1.0 equivalent, particularly 0.3 to 0.1 equivalents of the isocyanate group of the polyisocyanate compound (c) with respect to the hydroxyl group of the vinyl monomer (b). The range of 0.9 equivalent is preferable from the viewpoints of production stability and physical properties of the non-aqueous polyurethane fine particle dispersion, particularly impact resistance.

  The content (solid content) of the non-aqueous polymer fine particle dispersion (C) is from the viewpoint of reducing the amount of organic solvent in the paint, and from the viewpoint of the smoothness and drying properties of the resulting coating film. It is preferable that it is 10 to 85 weight% in the total resin solid content of this, Preferably it is 20 to 60 weight%.

  The coating composition of the present invention contains the above components (A) to (C) and, if necessary, a pigment, another resin component, an organic solvent, a curing catalyst, a crosslinking agent, and a flow regulator. Further, paint additives such as a color separation inhibitor, an ultraviolet absorber, a light stabilizer, an antioxidant, a surface conditioner, a pigment dispersant, and a curing catalyst can be contained.

  As pigments, colored pigments, metallic pigments, extender pigments, etc. can be used. Examples of colored pigments include white pigments such as titanium oxide, carbon black, acetylene black, lamp black, bone black, graphite, iron black, and aniline black. Black pigment, yellow iron oxide, titanium yellow, monoazo yellow, condensed azo yellow, azomethine yellow, bismuth vanadate, benzimidazolone, isoindolinone, isoindoline, quinophthalone, benzidine yellow, permanent yellow, etc. yellow pigment, permanent orange Orange pigments such as red iron oxide, naphthol AS azo red, ansanthrone, anthraquinonyl red, perylene maroon, quinacridone red pigment, diketopyrrolopyrrole, watching red, permanent red Red pigments, violet pigments such as cobalt violet, quinacridone violet, and dioxazine violet, blue pigments such as cobalt blue, phthalocyanine blue, and selenium blue, and green pigments such as phthalocyanine green. Examples of metallic pigments include aluminum powder. , Bronze powder, copper powder, tin powder, lead powder, zinc powder, iron phosphide, pearl metal coating mica powder, mica iron oxide and the like. Examples of extender pigments include barita powder, precipitated barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, silica, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white, gloss white, and mica powder.

  Examples of other resin components include polyester resins, alkyd resins, and cellulose acetate butyrate-modified acrylic resins.

  Examples of organic solvents include hydrocarbon solvents such as toluene, xylene and mineral spirits; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate and diethylene glycol monobutyl ether acetate; methyl ethyl ketone and methyl isobutyl Ketone solvents such as ketone, diisobutyl ketone and cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol and isobutanol; n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether Ether type such as: Swazol 310, Swazol 1000, Swazol 1500 (all are Cosmo Oil Co., Ltd.), SH Aromatic petroleum solvents such as ELLSOL A (Shellsol A, manufactured by Shell Chemical Co., Ltd.) can be used. These organic solvents can be used alone or in combination of two or more.

  The present invention also provides a coating finishing method in which the base material surface is coated with the coating composition of the present invention obtained as described above as a base coating, and then a top clear coating is applied.

  Examples of the base material surface include those obtained by applying a normal putty or primer coating to a metal or plastic material, and further an old paint film surface of an automobile body.

  The coating composition of the present invention is usually applied to the surface of the substrate so that the dry film thickness is in the range of 5 to 80 μm, whereby a base coat film is obtained. The base coat coating may be cured before the top clear coating is applied, or the top clear coating can be applied wet-on-wet onto the base coat coating.

  As the top clear paint used in the method of the present invention, conventionally known top clear paints can be used without particular limitation, and mainly include organic solvent-type paints (including non-aqueous dispersion type). For example, a crosslinkable functional group such as a hydroxyl group is used. Curing type paint mainly composed of acrylic resin or fluororesin and a crosslinking agent such as (block) polyisocyanate compound or melamine resin, or lacquer paint mainly composed of cellulose acetate butyrate modified acrylic resin In particular, those containing at least one hydroxyl group-containing resin selected from acrylic resins, fluorine resins, polyester resins, and modified resins thereof, and a polyisocyanate compound can be preferably used. When such a urethane curable paint is used as the top clear paint, the polyisocyanate compound partially penetrates from the top clear paint film into the best paint film. In the case where a hydroxyl group is present in the coating composition, the coating performance such as adhesion is improved without using a crosslinking agent component in the base coat paint.

  If necessary, the top clear paint may further contain paint additives such as polymer fine particles, a curing catalyst, an ultraviolet absorber, an antioxidant, a surface conditioner, and an antifoaming agent. The coating film with the top clear coating is suitably in the range of 20 to 100 μm in cured coating thickness.

  As the coating method, normal spray coating, electrostatic coating, and the like are adopted for both the base coat paint and the top clear paint, but other coating methods can be appropriately used without particular limitation.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Hereinafter, both “parts” and “%” are based on weight.

Acrylic resin (A-1) production flask was charged with 90 parts of xylene and stirred at 110 ° C. with stirring while blowing nitrogen gas, 10 parts of styrene, 30 parts of methyl methacrylate, 10 parts of i-butyl methacrylate. A mixture of 26 parts of n-butyl acrylate, 19 parts of 2-hydroxyethyl methacrylate, 4 parts of 2-ethylhexyl methacrylate, 1 part of acrylic acid and 1 part of 2,2′-azobisdimethylvaleronitrile over 3 hours It was dripped at a uniform speed. After completion of the dropwise addition, the temperature was kept at 110 ° C. for 1 hour and stirring was continued. Thereafter, 0.5 part of t-butylperoxyethyl hexanate dissolved in 10 parts of xylene as an additional catalyst was dropped at a uniform rate over 1 hour and further aged at the same temperature for 1 hour to obtain a solid content of 50%. An acrylic resin solution (A-1) was obtained. The weight average molecular weight of the obtained acrylic resin was 50,000, and the glass transition temperature was 29 ° C.

Acrylic resin (A-2) production flask was charged with 90 parts of xylene and stirred at 110 ° C. while blowing nitrogen gas, 10 parts of styrene, 10 parts of methyl methacrylate, 42 parts of i-butyl methacrylate, acrylic acid Uniform mixture of 10 parts of n-butyl, 19 parts of 2-hydroxyethyl methacrylate, 8 parts of 2-ethylhexyl methacrylate, 1 part of acrylic acid and 2.5 parts of 2,2′-azobisdimethylvaleronitrile over 3 hours It was dripped at a speed. After completion of the dropwise addition, the temperature was kept at 110 ° C. for 1 hour and stirring was continued. Thereafter, 0.5 part of t-butylperoxyethyl hexanate dissolved in 10 parts of xylene as an additional catalyst was dropped at a constant rate over 1 hour and further aged at the same temperature for 1 hour to obtain a solid content of 50%. An acrylic resin solution (A-2) was obtained. The resulting acrylic resin had a weight average molecular weight of 15,000 and a glass transition temperature of 41 ° C.

Synthesis and synthesis example 1 of macromonomer
A flask was charged with 66 parts of 3-ethoxyethyl propionate and 9 parts of 2,4-diphenyl-4-methyl-1-pentene (hereinafter sometimes abbreviated as “MSD”), and nitrogen was blown at 160 ° C. While stirring, a mixed solution of 100 parts of isobutyl methacrylate and 4 parts of “VR110” (manufactured by Wako Pure Chemical Industries, Ltd., azo radical polymerization initiator) was added dropwise over 3 hours. After stirring for 30 minutes, the temperature in the flask was cooled and maintained at 115 ° C. over 30 minutes, and 2.4 parts of “V59” (manufactured by Wako Pure Chemical Industries, Ltd., azo radical polymerization initiator) A mixed solution of 200 parts of butyl acetate and 200 parts of isobutyl methacrylate was added dropwise over 3 hours. After stirring for 30 minutes, a mixed solution of 1 part of “V59” and 10 parts of butyl acetate was added dropwise over 30 minutes. The temperature was maintained for 30 minutes, then cooled and diluted with 33 parts of butyl acetate to obtain a macromonomer solution (a-1) having a solid content of 50%. The obtained macromonomer has a weight average molecular weight of 9,000. According to the analysis by proton NMR, 97% or more of the ethylenically unsaturated groups derived from MSD are present at the end of the polymer chain, and 2% disappear. It was.

  The analysis method by proton NMR is as follows. The peak (4.8 ppm, 5.1 ppm) based on the proton of the unsaturated group of MSD is based on the proton of the ethylenically unsaturated group at the end of the polymer chain by addition-cleavage type chain transfer polymerization using deuterated chloroform as the solvent. It changes to a peak (5.0 ppm, 5.2 ppm). Assuming that aromatic protons (7.2 ppm) derived from MSD do not change in the polymerization step, each unsaturated group (unreacted, polymer chain end, disappearance) was quantified based on this assumption.

Synthesis example 2
Into the flask, 70 parts of 3-ethoxyethyl propionate and 8 parts of MSD were charged and stirred while blowing nitrogen at 160 ° C., in which 60 parts of 2-ethylhexyl methacrylate, 30 parts of glycidyl methacrylate, 2-hydroxypropyl methacrylate 10 And 5 parts of “Perhexyl D” (manufactured by NOF Corporation, peroxide radical polymerization initiator) were added dropwise over 3 hours. After stirring for 30 minutes, the temperature in the flask was cooled and maintained at 115 ° C. over 30 minutes, and 2.4 parts of “V59”, 200 parts of butyl acetate, 120 parts of 2-ethylhexyl methacrylate, and glycidyl methacrylate were contained therein. A mixture of 60 parts and 20 parts of 2-hydroxypropyl methacrylate was added dropwise over 3 hours. After stirring for 30 minutes, a mixture of 1 part of “V59” and 10 parts of butyl acetate was added dropwise over 30 minutes. The mixture was kept at the same temperature for 30 minutes, then cooled and diluted with 30 parts of butyl acetate to obtain a macromonomer solution (a-2) having a solid content of 50%. The obtained macromonomer has a weight average molecular weight of 8,800, and according to analysis by proton NMR, 97% or more of the ethylenically unsaturated groups derived from MSD are present at the end of the polymer chain, and 2% disappear. It was.

Synthesis Example 3 (for comparative example)
12-Hydroxystearic acid was subjected to dehydration condensation under toluene reflux using methanesulfonic acid as a catalyst, and the condensation was carried out to a resin acid value of 30. A macromonomer having a solid content of 70% was introduced by adding glycidyl methacrylate to the terminal carboxyl group of the obtained self-condensed polyester resin having a number average molecular weight of about 1,800 using dimethylaminoethanol as a catalyst to introduce a polymerizable double bond. A solution (a-3) was obtained. The obtained macromonomer had an average of about 1.0 polymerizable unsaturated double bonds per molecule.

Production and production example 1 of non-aqueous polymer fine particle dispersion
After adding 65 parts of butyl acetate to the flask and raising the temperature to 90 ° C., 50 parts of 50% macromonomer solution (a-1), 25 parts of 2-hydroxyethyl acrylate, “PLACCEL FA-2D” (Daicel Chemical Industries, Ltd., trade name, ε-caprolactone-modified hydroxyl group-containing acrylic monomer) 30 parts and a mixture of 2,2′-azobisisobutyronitrile 0.5 part was added dropwise at a uniform rate over 5 hours. Further, the mixture was aged at the same temperature for 2 hours to obtain a non-aqueous polymer fine particle dispersion (C-1) having a solid content of 47%. The average particle size of the obtained polymer fine particles was measured by using a quasi-elastic light scattering method according to “Coulter N4 model” manufactured by Coulter Co., and found to be about 600 nm.

Production Example 2
A mixture of 60 parts of butyl acetate and 20 parts of “Coronate R-300” (trade name, polyisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to the polymer fine particle dispersion (C-1) at a uniform rate over 1 hour. Then, the mixture was further aged at the same temperature, and cooled when 99.5% or more of the dropped isocyanate groups reacted to obtain a non-aqueous polyurethane fine particle dispersion (C-2) having a solid content of 40%. The isocyanate group was quantified by a method in which dibutylamine was excessively added to the sample during the reaction to consume the isocyanate group, and the remaining dibutylamine was back titrated with a hydrochloric acid solution. A bromphenol blue ethanol solution was used as the indicator, and the end point was when the color of the sample changed from blue to yellow-green. Further, the average particle diameter of the obtained polyurethane fine particles was measured by using a quasi-elastic light scattering method according to “Coulter N4 model” manufactured by Coulter Co., and was about 650 nm.

Production Example 3
After adding 60 parts of butyl acetate to the flask and raising the temperature to 90 ° C., 60 parts of a 50% macromonomer solution (a-2), 50 parts of 2-hydroxyethyl acrylate, and 2,2′- A mixture of 0.5 parts of azobisisobutyronitrile was added dropwise at a uniform rate over 5 hours and aged at the same temperature for 2 hours to obtain a non-aqueous polymer fine particle dispersion. The average particle diameter of the obtained polymer fine particles was measured by a quasi-elastic light scattering method according to “Coulter N4 model” manufactured by Coulter Co., and found to be about 300 nm.

  To this polymer fine particle dispersion, a mixture of 60 parts of butyl acetate and 20 parts of hexamethylene diisocyanate was added dropwise at a uniform rate over 1 hour, and the mixture was further aged at the same temperature. It cooled at the time of reaction, and obtained the nonaqueous polyurethane fine particle dispersion liquid (C-3) of 40% of solid content. The average particle diameter of the obtained polyurethane fine particles was measured by a quasi-elastic light scattering method using a “Coulter N4 model” manufactured by Coulter Co., and found to be about 350 nm.

Production Example 4 (for comparative example)
After adding 65 parts of butyl acetate to the flask and raising the temperature to 90 ° C., 40 parts of a 50% macromonomer solution (a-3), 45 parts of 2-hydroxyethyl acrylate, and 2,2′- A mixture of 0.5 parts of azobisisobutyronitrile was dropped at a uniform rate over 5 hours, and further aged for 2 hours at the same temperature to obtain a non-aqueous polymer fine particle dispersion (C-4) having a solid content of 43%. Obtained. The average particle size of the obtained polymer fine particles was measured by a quasi-elastic light scattering method according to “Coulter N4 model” manufactured by Coulter Co., and found to be about 250 nm.

Preparation of coating composition “Alpaste 96-0636” (Toyo Aluminum Co., 70% aluminum paste), organic solvent, and “Fronon SA-285” (Kyoeisha Chemical Co., Ltd., aluminum pigment settling inhibitor) are shown in Table 1. It mix | blends as shown, mixes and stirs, Furthermore, the 50% acrylic resin solution obtained by each manufacture example, the nonaqueous polymer fine particle dispersion, "CAB-551-0.2" (Eastman Chemical Japan company make) , Cellulose acetate butyrate) 25% solid content butyl acetate solution was blended as shown in Table 1, mixed and stirred to obtain each coating composition.

Evaluation of Storage Stability Each coating composition obtained as described above was sealed, and the state after standing at 40 ° C. for 2 weeks was evaluated according to the following criteria. The results are shown in Table 2.

○: There was no abnormality in appearance such as separation and puncture, and the viscosity was not changed from the initial state. ×: Significant change in viscosity was recognized compared to the initial state.

Evaluation of the amount of the organic solvent in the paint at the time of coating The coating composition obtained as described above was used as a metallic base paint, and a composition of butyl acetate / xylene / toluene / propylene glycol monomethyl ether acetate = 10/40/30/20% by weight. Was used to adjust the viscosity to 12 to 13 seconds (Ford Cup # 4, 25 ° C.). The obtained diluted paint was heated at 105 ° C. for 3 hours to determine the volatile content (amount of organic solvent). The results are shown in Table 2.

Preparation of test plate A 0.8 mm x 100 mm x 300 mm dull steel plate chemically treated with zinc phosphate, "Electron No. 9600" (manufactured by Kansai Paint Co., Ltd., epoxy resin-based cationic electrodeposition paint), "TP-65 Gray (Made by Kansai Paint, polyester / melamine resin-based automotive intermediate coating), “Majicron TB-510 Silver” (made by Kansai Paint, acrylic / melamine resin-based automotive topcoat) and “Magiclon TC-71 clear” ( An acrylic / melamine resin-based automobile topcoat clear paint manufactured by Kansai Paint Co., Ltd.) was applied in this order to form a cured coating film. This cured coating film was polished using # 2000 water-resistant abrasive paper, and degreased with petroleum benzine to obtain an article to be coated.

  Each metallic base paint diluted by the above-described evaluation of the amount of organic solvent in the paint during coating was applied to the object to be coated with a spray gun so that the dry film thickness was 15 μm, and was allowed to stand for 10 minutes. Furthermore, "Letane PG Multiclear HX (Q)" (manufactured by Kansai Paint Co., Ltd., two-pack type urethane clear paint) is applied thereon using a spray gun so that the dry film thickness is 40 to 50 μm. Each test plate was obtained by drying for a week.

  About each obtained test board, adhesiveness, water resistance, and finishing property were evaluated. Moreover, the drying property was evaluated when the metallic base paint was applied. The evaluation method is as follows. The results are shown in Table 2.

  (* 1) Adhesiveness: The test plate was cut so that 100 grids of 2 mm × 2 mm were formed, and a peel test was performed using a cellophane tape. The evaluation criteria are as follows.

○: No more than 20 peeled grids ×: More than 20 peeled grids

  (* 2) Water resistance: The coating state after the test plate was immersed in warm water at 40 ° C. for 10 days was visually evaluated. The evaluation criteria are as follows.

○: No abnormality ×: Abnormality such as luster or swelling

  (* 3) Finishability: Visual evaluation was performed on the metallic unevenness of the test plate and the smoothness of the clear coating surface. The evaluation criteria are as follows.

Metallic unevenness; ○: No unevenness, ×: Unevenness occurs Clear smoothness; ○: Good smoothness, ×: Inferior gloss and smoothness

  (* 4) Drying: 5 minutes after applying the metallic base paint, the paint film was touched with a finger to check for stickiness. The evaluation criteria are as follows.

○: No stickiness ×: Stickiness

Claims (11)

A coating composition containing an acrylic resin (A), a cellulose derivative (B), and a non-aqueous polymer fine particle dispersion (C), wherein the non-aqueous polymer fine particle dispersion (C) is 2,4- In the presence of a macromonomer (a) having a structure represented by the following formula (1) at the molecular end obtained by radical polymerization of an ethylenically unsaturated monomer in the presence of diphenyl-4-methyl-1-pentene In addition, the vinyl monomer (b) is dissolved in the macromonomer (a) and the vinyl monomer (b), but the polymer formed from the vinyl monomer (b) is substantially dissolved. A coating composition obtained by copolymerization in an organic solvent that does not.

The coating composition according to claim 1, wherein the acrylic resin (A) has a weight average molecular weight of 10,000 to 100,000 and a glass transition temperature of -10 to 80 ° C. The coating composition according to claim 1, wherein the content (solid content) of the acrylic resin (A) is 10 to 85% by weight in the total resin solid content in the coating. The coating composition according to claim 1, wherein the content (solid content) of the cellulose derivative (B) is 5 to 50% by weight in the total resin solid content in the coating. 70% by mole or more of the ethylenically unsaturated monomer constituting the macromonomer (a) in the non-aqueous polymer fine particle dispersion (C) is an ethylenically unsaturated monomer having a methacryloyl group. The coating composition according to claim 1. The non-aqueous polymer fine particle dispersion (C) is converted into a polyisocyanate into a non-aqueous polymer fine particle dispersion containing 5 to 100% by weight of a hydroxyl group-containing vinyl monomer in the vinyl monomer (b). Compound (c) is blended so that the isocyanate group of polyisocyanate compound (c) is within the range of 0.2 to 1.0 equivalent to the hydroxyl group of vinyl monomer (b). The coating composition according to claim 1, which is a non-aqueous polyurethane fine particle dispersion obtained by reacting a hydroxyl group and an isocyanate group inside the coalesced fine particles. The coating composition according to claim 1, wherein the content (solid content) of the non-aqueous polymer fine particle dispersion (C) is 10 to 85% by weight in the total resin solid content in the coating. Furthermore, the coating composition of Claim 1 containing a pigment. 9. A finishing method in which a base coat paint is applied to a substrate surface, and then a top clear paint is applied, and the paint composition according to any one of claims 1 to 8 is used as the base coat paint. The paint finishing method according to claim 9, wherein the top clear paint contains a hydroxyl group-containing resin and a polyisocyanate compound. A coated article obtained by the paint finishing method according to claim 9 or 10.