JP4836542B2 - Paint composition - Google Patents

Description

  To form a coating film with excellent finish, dryness, hardness, adhesion, etc., without substantially containing volatile organic compounds such as toluene and xylene, which are being suppressed due to environmental impact A suitable coating composition is provided.

Conventionally, in the field of automobile repair coatings, acrylic lacquers and acrylic urethane coatings are mainly used because the coating film is dried under conditions of room temperature drying or forced drying.
When lacquer type paint is used in this field, polyester resin and cellulose acetate butyrate (sometimes referred to as CAB) are blended from the viewpoint of the drying property of the coating film, and polyester resin and CAB are blended with acrylic resin. Paints based on the vehicle as the main component have been adopted, but the compatibility of each component is inadequate, resulting in an adverse effect on the finish. Phenomenon that orientation is disturbed (sometimes referred to as “Fukimura”), and when the clear coating is applied repeatedly on a paint film containing pigment, the orientation of the pigment is disturbed (sometimes referred to as “modulation unevenness”), resulting in poor finish. There were problems such as.

  In order to solve these problems, the present applicant has proposed a coating composition using a CAB graft copolymer, a polyester resin and an acrylic resin in specific ratios in Patent Documents 1 and 2. According to the composition, the compatibility of each of these components is improved, and a coating film having a good finish can be formed without causing unevenness and unevenness even in metallic coating. An organic solvent such as toluene or xylene was blended in the diluted thinner for adjusting the viscosity.

Generally, a paint prepared by a paint manufacturer is not used as it is because of its high viscosity, and the paint manufacturer ships to a distributor together with a diluted thinner. The painter purchases both products from the dealer and mixes the paint and dilution thinner for use in painting to adjust the viscosity and paint workability according to the purpose.
In recent years, the impact of volatile organic compounds on the environment has become a problem, and organic solvents such as toluene and xylene that have been conventionally blended in the field of paints are regulated substances (for example, discharge of environmental pollutants). It is required to reduce or substantially not contain these organic solvents in both paints and diluted thinners (POLLUTANT RELEASE AND TRANSFER REGISTER (hereinafter abbreviated as PRTR)).

  By the way, Patent Document 3 includes a specific (meth) acrylic copolymer, a polyisocyanate compound and a specific amount of an organic solvent, and the organic solvent is an aliphatic or aromatic hydrocarbon solvent and has a specific solubility parameter. In addition, an automotive repair coating composition characterized by having a specific boiling point is disclosed. When this coating composition is used as a clear coating in metallic coating, the occurrence of mottling unevenness can be suppressed, and a metallic finish with a good appearance can be obtained. However, when this composition is used as a base coating, it is formed. The finish, drying and adhesion of the coating film are not sufficient, and there remains a problem that organic solvents such as toluene and xylene are blended in the paint.

As measures against the above-mentioned problems, for example, in paint compositions such as base coats and clears used in conventional metallic paints, organic solvents such as toluene and xylene are excluded from paint or diluted thinner, and paints such as ester organic solvents are used. If the resin is completely replaced with an organic solvent that dissolves, not only the mottling unevenness that occurs when the clear paint is applied after the base coat is applied, but also the unevenness that occurs when the base coat is applied, especially when the base coat is applied repeatedly. The organic solvent causes redissolving of the coating film, and there is a problem that the finish performance is remarkably lowered by replacing the solvent.
JP 2000-178500 A JP 2002-129090 A JP-A-6-256715

  An object of the present invention is a paint suitable for forming a coating film that is substantially free of regulated volatile organic compounds, has good coating workability and finish, and is excellent in water resistance and adhesion. It is to provide a composition.

As a result of intensive investigations to solve the above problems, the inventors of the present invention have developed a specific paint composition comprising a specific resin composition and a base paint containing an organic solvent and a diluent containing a specific amount of a specific organic solvent. The present inventors have found that the above-mentioned problems can be solved and have reached the present invention.
That is, the present invention provides a coating composition comprising a base coating (I) and a diluent (II), wherein the base coating (I) comprises a cellulose derivative (A), an acrylic resin (B), a polyester resin (C ) And at least one organic solvent (D) selected from ester organic solvents and ketone organic solvents, and the cellulose derivative (A) is the sum of component (A), component (B) and component (C). 5 to 75% by weight in the solid content, and the diluent (II) contains the aliphatic hydrocarbon organic solvent (E) in the diluent (II) in an amount of 5 to 90% by weight, preferably The present invention relates to a coating composition, wherein the base coating is a metallic base coating, and a coating method using the coating composition.

  According to the coating composition of the present invention, it is substantially free of regulated volatile organic compounds, is considered for the environment and the human body, and contains a specific resin and an organic solvent. Since the compatibility of each component is good, the storage stability can be good, and by adding a diluent containing a specific amount of a specific solvent to the base paint, the coating composition at the time of coating is It can have a specific solvent composition, and can form a coating film excellent in finish, water resistance, adhesion and the like even under normal temperature drying or forced drying conditions. In addition, according to the coating composition, the re-dissolution at the time of recoating is suppressed, and even in the case of a metallic coating in which a phenomenon such as unevenness and mottling unevenness is likely to occur, the orientation of the metallic pigment is not disturbed and the finish is excellent. Can be formed.

Cellulose derivative (A)
In the present invention, the cellulose derivative (A) is a compound containing cellulose as a structural unit. For example, a cellulose esterified product in which a hydroxyl group of cellulose is esterified with an acid such as fatty acid or nitric acid, and polymerizable to the esterified product of cellulose. Examples thereof include a copolymer (F) obtained by reacting a polymerizable unsaturated group-containing cellulose ester obtained by introducing an unsaturated group with a polymerizable unsaturated monomer.

Examples of the esterified product of cellulose include nitrocellulose, cellulose acetate butyrate, cellulose acetate, and cellulose acetate propionate. Of these, cellulose acetate butyrate can be suitably used.
Cellulose acetate butyrate is obtained by further butyl esterifying a partially acetylated product of cellulose, and preferably has an acetyl group content of generally 1 to 30% by weight.
The 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” (above, US East For example, Man Chemical Co., Ltd., trade name).

The cellulose derivative (A) can improve the drying property and adhesion of the coating film obtained, and when the coating composition of the present invention contains a bright pigment such as aluminum powder, The orientation of the glitter pigment can be improved.
The number average molecular weight of the cellulose acetate butyrate is preferably in the range of 15,000 to 100,000, particularly 20,000 to 35,000. Within this range, while maintaining compatibility with an acrylic resin or a polyester resin, the coating unevenness and the modulation unevenness phenomenon can be suppressed when the coating composition of the present invention is applied, and a coating film with good finish can be formed. Can do.

  In this specification, the number average molecular weight is a value obtained by converting the number average molecular weight measured with a gel permeation chromatograph (trade name, “HLC8120GPC” manufactured by Tosoh Corporation) based on the number average molecular weight of polystyrene. is there. 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 cc / min, detector: RI.

In the present invention, the cellulose derivative (A) reacts the esterified product of cellulose and a polymerizable unsaturated group-containing cellulose ester obtained by introducing a polymerizable unsaturated group into the esterified product and a polymerizable unsaturated monomer. The copolymer (F) formed can be included.
Particularly in the present invention, by using the esterified cellulose and the copolymer (F) in combination, the compatibility of the resins contained in the base coating (I) is improved, and the finish of the formed coating film is improved. Can be improved.

Examples of the copolymer (F) include copolymerization of a polymerizable unsaturated group-containing cellulose ester and a polymerizable unsaturated monomer obtained by reacting a cellulose esterified product with an isocyanate group-containing polymerizable unsaturated monomer. Can be manufactured.
As the polymerizable unsaturated monomer, any polymerizable monomer having an ethylenically unsaturated bond can be used. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i- Propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) Straight chain having 1 to 18 carbon atoms such as acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (manufactured by Osaka Organic Chemical Co., Ltd.) Or containing branched hydrocarbon groups Polymerizable unsaturated monomer to be polymerized; polymerizable unsaturated monomer having a cycloalkyl group such as cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate; isobornyl ( Polymerizable unsaturated monomers having an isobornyl group such as meth) acrylate; polymerizable unsaturated monomers having an adamantyl group such as adamantyl (meth) acrylate; aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene; -Acryloyloxyethyl) acid phosphate, (2-methacryloyloxyethyl) acid phosphate, (2-acryloyloxypropyl) acid phosphate, (2-methacryloyloxypropyl) ) Phosphoric acid group-containing polymerizable unsaturated monomers such as acid phosphate; 2-hydroxyethyl (meth) acrylate, 2
- hydroxypropyl (meth) acrylate - DOO, 3-hydroxypropyl (meth) acrylate, _C 2 -C ₈ hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylate, allyl alcohol - le, the _C 2 -C ₈ hydroxy (Meth) acrylate having a hydroxyl group such as a modified ε-caprolactone of alkyl (meth) acrylate; a hydroxyl group-containing polymerizable unsaturated monomer such as (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end; Carboxyl group-containing polymerizable unsaturated monomers such as acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyl Oh Alkoxysilyl group-containing polymerizable unsaturated monomers such as cyclopropyltrimethoxysilane and γ- (meth) acryloyloxypropyltriethoxysilane; perfluorobutylethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate and the like Alkyl (meth) acrylate; polymerizable unsaturated monomer having a fluorinated alkyl group such as fluoroolefin; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3 , 4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and other epoxy group-containing polymerizable unsaturated monomers such as allyl glycidyl ether; Polymerizable unsaturated monomer having a photopolymerizable functional group such as 1, 2,2,6,6-pentamethylpiperidyl (meth) acrylate, 2,2,2,6,6-tetramethylpiperidinyl ( (Meth) acrylates, etc .; vinyl compounds such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate; (meth) acrylonitrile, etc .; containing amide groups such as (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, etc. Polymerizable unsaturated monomer; N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, glycidyl (meth) acrylate and amines Amino group-containing polymerizable unsaturated monomers such as adducts of 2-; Tacryloyloxy) ethyltrimethylammonium chloride, 2- (methacryloyloxy) ethyltrimethylammonium bromide, methacryloylaminopropyltrimethylammonium chloride, methacryloylaminopropyltrimethylammonium bromide, tetrabutylammonium (meth) acrylate, tetramethylammonium (meth) acrylate, Quaternary ammonium base-containing polymerizable unsaturated monomers such as trimethylbenzylammonium (meth) acrylate and 2- (methacryloyloxy) ethyltrimethylammonium dimethyl phosphate; (meth) acrylate having a polyoxyalkylene chain whose molecular terminal is an alkoxy group; 2-acrylamido-2-methylpropanesulfonic acid, allylsulfone Polymerizable unsaturated monomers having a sulfonic acid group such as acid, sodium styrenesulfonate, sulfoethyl methacrylate and sodium and ammonium salts thereof; acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, Examples thereof include carbonyl group-containing polymerizable unsaturated monomers such as vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone). These may be used alone or in combination of two or more. Can be used in combination.

  Examples of the isocyanate group-containing polymerizable unsaturated monomer for introducing a polymerizable unsaturated group into the esterified product of cellulose include isocyanates such as isocyanatoethyl acrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate. A group-containing vinyl monomer or a product obtained by addition reaction of a diisocyanate and the above-mentioned hydroxyl group-containing polymerizable unsaturated monomer can be used.

The copolymerization reaction of the polymerizable unsaturated monomer and the esterified product of polymerizable unsaturated group-containing cellulose can be performed by a solution polymerization method or the like in the presence of a radical polymerization initiator such as an organic peroxide.
In the copolymer (F), the use ratio of the polymerizable unsaturated monomer / cellulose esterified product is preferably 5/95 to 95/5, preferably 10/90 to 90/10. is there.

Acrylic resin (B)
In the present invention, the acrylic resin (B) is a component that can be used mainly as a film-forming component and also as a pigment-dispersed resin, and a polymerizable unsaturated monomer is co-polymerized using a polymerization initiator in the presence of an organic solvent. The resin obtained by superposing | polymerizing can be mentioned.
Such a polymerizable unsaturated monomer can be appropriately selected from those listed in the description of the cellulose derivative (A).

In the present invention, the acrylic resin (B) is a glass transition of a copolymer composed of a polymerizable unsaturated monomer constituting the acrylic resin (B) from the viewpoints of adhesion of the formed coating film, water adhesion and polishing workability. It is desirable that the temperature is in the range of 0 to 80 ° C, preferably 5 to 75 ° C.
In this specification, the glass transition temperature (absolute temperature) is a value calculated by the following formula.

1 / Tg = W ₁ / T ₁ + W ₂ / T ₂ +... W _n / T _{n
Wherein, W 1, W 2 ··· W} n is the weight percent of each monomer [= (amount / total weight of the monomers in each monomer) × _{100], T 1, T 2 ··· T} n each It is the glass transition temperature (absolute temperature) of the homopolymer of the monomer. In addition, the glass transition temperature of the homopolymer of each monomer is a value according to Polymer Hand Book (4th Edition), and the glass transition temperature of the homopolymer of the monomer not described in the document is a weight average of the homopolymer of the monomer. The sample synthesized with a molecular weight of about 50,000 is used as a sample. Using a differential scanning thermal analysis “DSC-50Q type” (trade name, manufactured by Shimadzu Corporation), the sample is taken into a measuring cup and vacuumed. After removing the solvent, the calorie change is measured in the range of −100 ° C. to + 100 ° C. at a temperature rising rate of 3 ° C./min, and the first baseline change point on the low temperature side is used.

  As a suitable copolymerization component in the said acrylic resin (B), the said hydroxyl-containing polymerizable unsaturated monomer can be mentioned, As the usage-amount of this monomer, all the polymerization used for manufacture of an acrylic resin (B) is mentioned. It is suitable from the point of the adhesiveness of a formed coating film, and water resistance that it is 0.1 to 35 weight% in a unsaturated unsaturated monomer, Preferably it exists in the range of 1 to 30 weight%. By copolymerizing the monomer, it is possible to improve the adhesion of the coating film formed from the finally obtained coating composition, and it is also possible to react with the curing agent contained in the clear coating material. .

  Moreover, it is desirable that the acrylic resin (B) contains a carboxyl group-containing polymerizable unsaturated monomer as a copolymerization component from the viewpoint of adhesion of the formed coating film or pigment dispersibility. As the usage-amount of this carboxyl group-containing polymerizable unsaturated monomer, it is 0.05 to 10 weight% in all the polymerizable unsaturated monomers used for manufacture of an acrylic resin (B), Preferably it is 0.07 to 5.0. It can be in the range of weight percent.

  In addition, the acrylic resin (B) is an amino group-containing polymer from the viewpoint of improving the dispersibility of the pigment and the appearance of the multilayer coating film when the clear coating is applied onto the coating film of the coating composition of the present invention. It is desirable to comprise a polymerizable unsaturated monomer. The amount of the amino group-containing polymerizable unsaturated monomer used is 0.1 to 60% by weight, preferably 0.5 to 50% by weight, based on the total polymerizable unsaturated monomer used in the production of the acrylic resin (B). Can be within the range of

As the polymerization initiator used in the production of the acrylic resin (B) in the present invention, conventionally known polymerization initiators used in the solution polymerization method can be used without limitation, and examples thereof include benzoyl peroxide, octanoyl peroxide, and lauroyl peroxide. Examples thereof include organic peroxides such as oxide and stearoyl peroxide; azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile). These can be used alone or in combination of two or more.

The amount of the polymerization initiator used is 0.1 to 10% by weight, preferably 0.2 to 8%, based on the total weight of all polymerizable unsaturated monomers used in the production of the acrylic resin (B). It is desirable to be within the range of wt%.
In the present invention, the acrylic resin (B) obtained as described above has a weight average molecular weight of 5,000 to 80,000, preferably 6,000 to 70,000 from the viewpoint of adhesion of the formed coating film and pigment dispersibility. It can be in the range of 000.

  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 cc / min, detector: RI.

Polyester resin (C)
In the present invention, examples of the polyester resin (C) include resins that can be obtained by copolymerizing a polybasic acid and a polyhydric alcohol as main components according to a conventional method. Examples of the polybasic acid include adipic acid, succinic acid, isophthalic acid, terephthalic acid, phthalic anhydride, maleic anhydride, trimellitic acid, hexahydrophthalic anhydride, sodium 5-sulfoisophthalate, and the like. Examples thereof include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, neopentyl glycol, 1,6-hexanediol, pentaerythritol, and sorbitol. Furthermore, monobasic acids such as dehydrated castor oil fatty acid, linseed oil fatty acid, soybean oil fatty acid and tol oil fatty acid, benzoic acid, and fats and oils can be used as a copolymerization component.

According to the coating composition of the present invention, by containing the polyester resin (C), the adhesion of the coating film formed from the coating composition of the present invention, in particular, a curing agent component from a clear coating containing a curing agent. Soaking can be promoted and adhesion to the clear coating film can be improved.
The polyester resin (C) has a weight average molecular weight in the range of 5,000 to 100,000, preferably 10,000 to 70,000, and a hydroxyl value of 5 to 150 mgKOH from the viewpoint of adhesion of the formed coating film. / G, preferably within the range of 10 to 140 mg KOH / g.

Further, the glass transition temperature of the polyester resin (C) may be in the range of −70 to 0 ° C., preferably −65 to −5 ° C. Here, the glass transition temperature of the polyester resin (C) is determined by using a differential scanning thermal analysis “DSC-50Q type” (trade name, manufactured by Shimadzu Corporation), taking a sample in a measuring cup, and vacuum-sucking the solvent. After removal, the calorie change is measured in the range of −100 ° C. to + 100 ° C. at a rate of temperature increase of 3 ° C./min, and the first baseline change point on the low temperature side is used.

Organic solvent (D)
In the present invention, the organic solvent (D) is preferably an organic solvent that does not adversely affect the drying property of the formed coating film and the coating environment, and the resin, particularly the cellulose derivative (A) in the coating composition of the present invention. And at least one organic solvent selected from ester-based organic solvents and ketone-based organic solvents.

  Examples of the ester organic solvent in the organic solvent (D) 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. Examples of ketone organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl isoamyl ketone, diisobutyl ketone, methyl hexyl ketone, and isophorone. These can be used alone or in combination of two or more.

The organic solvent (D) is preferably an organic solvent having a molecular weight in the range of 58 to 220, particularly 72 to 200. In particular, the ester organic solvent includes the storage stability of the base paint (I), and This has an effect of improving the compatibility with an aliphatic hydrocarbon organic solvent (E) described later, which is preferable.
The organic solvent (D) can be mixed in any stage of the production of the base paint (I), and can also be blended as a reaction solvent or a diluting solvent in the production of the resin contained in the paint.

Aliphatic hydrocarbon organic solvent (E)
In the present invention, the aliphatic hydrocarbon-based organic solvent (E) is preferably a compound having a high flash point and a high boiling point that does not adversely affect the environment and the human body. For example, n-butane, n-hexane N-heptane, n-pentane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, etc. Linear alkane; 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-trimethylpentane, 2,2,4-trimethylpentane, 3, -Diethylhexane, 2,6-dimethyloctane, 3,3-dimethyloctane, 3,5-dimethyloctane, 4,4-dimethyloctane, 3-ethyl-3-methylheptane, 2-methylnonane, 3-methylnonane, 4 -Branched alkanes such as methylnonane, 5-methylnonane, 2-methylundecane, 3-methylundecane, 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-methylethylsilane Cyclic alkanes such as rhohexane, 1,2,3-trimethylcyclohexane, 1,2,4-trimethylcyclohexane and 1,3,5-trimethylcyclohexane can be used, and these can be used alone or in combination of two or more. Can do.

In the present invention, for example, when the coating composition of the present invention is a metallic paint having a glitter pigment, the occurrence of unevenness of the formed coating film can be suppressed, and the finish can be improved satisfactorily. As the organic solvent (E), it is preferable to use an alkane having 5 to 12 carbon atoms, particularly 6 to 10 carbon atoms, particularly a cyclic alkane, more particularly an alkylcyclohexane.
Examples of the alkylcyclohexane include 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, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane and the like.

  In the present invention, the organic solvent (E) is preferably blended with the diluent (II) described later from the viewpoint of long-term storage stability of the base coating material (I), and the aliphatic solvent is contained in the diluent (II). It is desirable that the hydrocarbon-based organic solvent (E) is contained in an amount of 5 to 90% by weight, preferably 10 to 80% by weight. When the content of the organic solvent (E) in the diluent (II) is less than 5% by weight, the coating composition of the present invention obtained by blending the diluent (II) with the base coating (I) is applied. May cause unevenness in the finish of the coating film obtained, while if it exceeds 90% by weight, the solubility of the diluent (II) in the base paint (I) becomes insufficient, and the viscosity of the two is mixed. This is not preferable because the stability and finish of the prepared coating composition are lowered.

Base paint (I)
In the present invention, the base paint (I) comprises the above components (A), (B), (C) and (D) as essential components, and the cellulose derivative (A) is composed of the components (A) and (B). ) And component (C) in a total solid content weight of 5 to 75% by weight, preferably 10 to 70% by weight.

When the component (A) is less than 5% by weight, the drying property of the coating film formed from the coating composition of the present invention is lowered. On the other hand, when it exceeds 75% by weight, the adhesion to the coated surface and the clear coating film is reduced. This is undesirable because it decreases.
The acrylic resin (B) and the polyester resin (C) are preferably 5 to 90% by weight of the component (B) in the total solid weight of the component (A), the component (B) and the component (C). Is 10 to 85% by weight, and component (C) is contained in an amount of 5 to 45% by weight, preferably 10 to 40% by weight.

When the component (B) is less than 5% by weight, the adhesion to the coated surface and the clear coating film is lowered, while when it exceeds 90% by weight, the drying property of the formed coating film may be lowered. If it is less than 5% by weight, the penetration of the crosslinking component from the clear is insufficient, whereas if it exceeds 45% by weight, the coating film hardness may be lowered.
In the present invention, the base paint (I) may be either a colored paint or a clear paint. However, when the base paint (I) is a colored paint, particularly a glittering pigment-containing paint, the effect of the present invention is exhibited to the maximum. Can do.

As the pigment used in the base paint (I), pigments such as luster pigments, colored pigments and extender pigments which are usually used in the paint field can be used without particular limitation. For example, metallic pigments such as aluminum powder, bronze powder, copper powder, tin powder, iron phosphide; mica, metal oxide coated mica powder, metal iron oxide coated alumina flake, metal oxide coated silica flake, mica Pearl luster-like pigments such as iron oxide, etc. Coloring pigments include white pigments such as titanium oxide; black pigments such as carbon black, acetylene black, lamp black, bone black, graphite, iron black, and aniline black Yellow pigments such as yellow iron oxide, titanium yellow, monoazo yellow, condensed azo yellow, azomethine yellow, bismuth vanadate, benzimidazolone, isoindolinone, isoindoline, quinophthalone, benzidine yellow, permanent yellow, etc .; Red pigments such as red iron oxide, naphthol AS azo red, ansanthrone, anthraquinonyl red, perylene maroon, quinacridone red pigment, diketopyrrolopyrrole, watching red, permanent red; cobalt purple, quinacridone violet, di Purple pigments such as oxazine violet; blue pigments such as cobalt blue, phthalocyanine blue, and selenium blue; green pigments such as phthalocyanine green; and the like as extender pigments include zinc powder, barita powder, precipitated barium sulfate, Examples thereof include barium carbonate, calcium carbonate, gypsum, clay, silica, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white, gloss white, and mica powder.

  When the pigment is blended in the coating composition of the present invention, the blending amount can be appropriately adjusted according to the type of the pigment, and is generally 1 to 250% by weight based on the resin solid content weight in the coating, It is preferable that the content be in the range of 2 to 240% by weight. For example, in the case of a paint containing a bright pigment, the bright pigment can be contained in an amount of 1 to 60% by weight, preferably 2 to 55% by weight.

  If necessary, the base paint (I) is further blended with paint additives such as thickeners, ultraviolet absorbers, light stabilizers, antioxidants, surface conditioners, pigment dispersants, and curing catalysts. be able to. Moreover, the said organic solvent (E) or another organic solvent can also be contained in the range which does not impair the storage stability of base coating material (I), the drying property of the coating composition of this invention finally obtained.

  The other organic solvent in the present invention is an organic solvent other than the organic solvent (D) and the organic solvent (E). Specific examples include aromatic hydrocarbon organic solvents such as toluene and xylene; 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, di Tylene 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, di Ether organic solvents such as propylene 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, benzy Can be exemplified an alcohol-based organic solvents such as alcohol, it can be used in a range that does not impair the performance of the coating film formed of the coating composition of the present invention.

Diluent (II)
In the present invention, the diluent (II) adjusts the viscosity of the paint in order to improve the coating workability, and further forms the above-described base paint ( I).
In the diluent (II), the mixing stability of the resin, particularly the cellulose derivative (A) and the diluent (II) contained in the base coating (I) is improved, and the coating formed by the coating composition of the present invention is used. In terms of improving the finish of the film, a specific example of a particularly preferable organic solvent composition in the diluent (II) is an aliphatic hydrocarbon organic based on the weight of the total organic solvent contained in the diluent (II). 5 to 90% by weight of solvent, preferably 10 to 80% by weight,
Ester organic solvent is 8 to 85% by weight, preferably 10 to 80% by weight
The ketone organic solvent is 2 to 35% by weight, preferably 5 to 30% by weight.
Other organic solvents are 0 to 30% by weight, preferably 0 to 25% by weight
It is preferable to be within the range.

The diluent (II) may further contain paint additives such as a thickener, an ultraviolet absorber, a light stabilizer, an antioxidant, a surface conditioner, a pigment dispersant, and a curing catalyst, if necessary. it can.
Coating Composition The coating composition of the present invention comprises the base coating (I) and the diluent (II), and has a resin solid content of 100 in the base coating (I) from the viewpoint of coating workability and finish. The organic solvent (D) is 100 to 700 parts by weight, preferably 120 to 690 parts by weight, and the organic solvent (E) is 20 to 340 parts by weight, preferably 25 to 330 parts by weight with respect to parts by weight. It is desirable to make it.

  In the present invention, the resin solid content in the base coating is 100 wt% from the viewpoint of improving the compatibility between the resins contained in the coating composition of the present invention finally obtained and forming a coating film with good finish. The aliphatic hydrocarbon organic solvent (E) is 20 to 340 parts by weight, preferably 25 to 330 parts by weight, and the ester organic solvent is 90 to 590 parts by weight, preferably 100 to 580 parts by weight, based on parts. The ketone organic solvent can be in the range of 10 to 110 parts by weight, preferably 20 to 110 parts by weight.

The coating material can be easily prepared, for example, by stirring and mixing the base coating material (I) and the diluent (II) immediately before coating. In the present specification, the term “immediately before painting” may include, for example, up to 3 hours before painting.
The blending amount of the diluent (II) with respect to the base paint (I) which can be the above solvent composition is, for example, the blending amount of the diluent (II) from the viewpoint of coating workability, stability of the paint after preparation and finish. but generally with respect to 100 parts by weight of the base paint (I), 20 to 250 [parts by weight, preferably in the range of 30 to 200 parts by weight.

The form of the paint in the paint composition of the present invention is not particularly limited, and is preferably a two-component composition comprising a base paint (I) and a diluent (II). Moreover, the coating composition of the present invention may further contain a curing agent such as a polyisocyanate curing agent, a blocked isocyanate curing agent, and a melamine curing agent, if necessary, and the coating composition contains the curing agent. In this case, the coating composition of the coating composition is a three-component type of base coating (I), diluent (II) and curing agent, depending on the type of curing agent, or base coating (I) and Mix the curing agent into a single liquid and combine it with a diluent (II), or use a mixture of a diluent (II) and a curing agent as a single liquid. It is possible to appropriately select whether to use a two-component type in combination with the paint (I).

Coating The present invention is a coating method characterized by coating the coating composition of the present invention on the surface to be coated.
Examples of the surface to be coated include a conventionally known base material surface and a coating surface provided on the base material, and the base material is not particularly limited. Metals such as plastics; Organic base materials such as plastics; Inorganic base materials such as concrete and wood, and the coating film provided on the base material are not particularly limited. For example, vehicles such as automobile bodies and trains And a multi-layer coating film formed from a base coating film and a clear coating film with a colored base coating provided on the base coating film, a primer coating film, an electrodeposition coating film, and an intermediate coating film under the base coating film. A coating film such as a film may be appropriately provided.

A base coating film by a colored base paint generally represents a coating film provided by a paint containing a coloring pigment and / or a luster pigment that is applied for the purpose of imparting cosmetic properties to the surface to be coated. Generally, it represents a coating film provided on the uppermost layer capable of forming a transparent coating film. The primer coating generally represents a coating directly provided on the substrate surface for reasons such as improved adhesion, and the electrodeposition coating generally represents a coating with a coating used for electrodeposition coating. The film generally represents a coating film provided between a coating film by an undercoating film such as a primer coating film or an electrodeposition coating film and a top coating film such as a base coating film or a top clear coating film.

The coating means for applying the coating composition of the present invention is not particularly limited, such as spray coating, electrostatic coating, brush coating, roller coating, and the drying method is any one of heat drying, forced drying, and room temperature drying. Also good. In this specification, the drying condition of less than 40 ° C. is room temperature drying, the drying condition of 40 ° C. or more and less than 80 ° C. is forced drying, and the drying condition of 80 ° C. or more is heat drying.
Moreover, this invention is a coating method characterized by coating the coating composition on the surface to be coated and then coating the clear coating on the coating film.

The coating film formed from the coating composition may be cured and dried before the clear coating is applied, or the clear coating may be applied onto the uncured coating and both coatings may be dried.
As the clear coating used in the method of the present invention, conventionally known clear coatings can be used without any particular limitation. For example, acrylic resins and fluororesins containing a crosslinkable functional group such as a hydroxyl group are the main ingredients, and block polyisocyanates, polyisocyanates and melamines are used. A curable paint containing a resin as a curing agent or a lacquer paint mainly composed of cellulose acetate butyrate-modified acrylic resin can be suitably used, and if necessary, pigments, fiber derivatives, and additive resins Further, paint additives such as ultraviolet absorbers, light stabilizers, surface conditioners, and curing catalysts can be contained. Among these, when a paint containing a polyisocyanate curing agent is used, the polyisocyanate curing agent partially permeates into the coating film of the coating composition from the clear coating film, so that the coating film of the coating composition of the present invention has a hydroxyl group. Can be reacted with the hydroxyl group, the curing agent component can be used in the coating composition or the amount can be reduced, and the adhesion between the coating film and the clear coating film can be improved. This is preferable because it is possible.

  The coating means for applying the clear paint is not particularly limited, such as spray coating, electrostatic coating, brush coating, roller coating, and the drying method may be any of heat drying, forced drying, and room temperature drying.

Hereinafter, the present invention will be described in more detail with reference to examples. Here, “parts” and “%” mean “parts by weight” and “% by weight”, respectively.
Production of polyester resin solution Production Example 1
The following components were charged into a 4 liter reactor equipped with a reflux condenser equipped with a heating device, a thermometer, a stirrer, a rectifying column and a water separator, heated to 160 ° C., and heated from 160 ° C. to 230 ° C. over 3 hours. The temperature was raised to ° C.

Hexahydrophthalic anhydride 29.7 parts Adipic acid 25.4 parts Neopentyl glycol 5.3 parts 1,6-Hexanediol 39.6 parts This was kept at 230 ° C. for 1 hour to produce condensed water (7. 4 parts) was distilled off using a rectification column. Subsequently, 5 parts of xylene was added, xylene and condensed water were refluxed, and water was removed using a water separator. Two hours after the addition of xylene, the acid value was measured, and when the acid value became 2 mgKOH / g or less, the pressure was reduced and xylene was distilled off almost completely. Then, it cooled to 120 degreeC and diluted with butyl acetate so that it might become 70% of non volatile matters, and the polyester resin butyl acetate solution was obtained. The weight average molecular weight of the resin was 20,000, the hydroxyl value was 32 mgKOH / g, and the glass transition temperature was −52 ° C.

Production of acrylic resin solution Production example 2
A reactor having a capacity of 4 liters equipped with a thermometer, a stirrer, a reflux condenser and a dropping pump was charged with 68 parts of butyl acetate, heated to 110 ° C. with stirring, and mixed with the following monomer mixture and polymerization initiator: Was added dropwise at a constant rate at 110 ° C. over about 3 hours.

Isobutyl methacrylate 59.75 parts Methyl methacrylate 10 parts "Isostearyl acrylate" (manufactured by Osaka Organic Chemical Co., Ltd.) 10 parts 2-hydroxyethyl acrylate 19 parts Dimethylaminoethyl methacrylate 1 part Methacrylic acid 0.25 parts Azobis (2,4-dimethyl) 0.2 parts of valeronitrile) After completion of dropping, the mixture was kept at 110 ° C. for 1 hour and stirring was continued. Then, 0.5 parts of azobisdimethylvaleronitrile dissolved in 14 parts of butyl acetate as an additional catalyst was added dropwise at a constant rate over 1 hour. And after completion | finish of dripping, it maintained at 110 degreeC for 1 hour, and complete | finished reaction. The obtained acrylic resin solution was a uniform and transparent solution having a nonvolatile content of 55.0%, the weight average molecular weight of the resin was 50,000, the hydroxyl value was 92 mgKOH / g, and the glass transition temperature was 57 ° C. .

Production of CAB graft acrylic resin solution Production Example 3
The following components were charged into a 4 liter reactor equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel, heated in a nitrogen gas atmosphere, and heated to 110 ° C. over about 4 hours.
Butyl acetate 600 parts “CAB-381-0.5” (Note 1) 200 parts After heating to 110 ° C., after confirming that “CAB-381-0.5” (Note 1) was completely dissolved, Heating was stopped and 133 parts of butyl acetate were distilled off under reduced pressure. The temperature in the reactor was 87 ° C. While maintaining this temperature, 11.1 parts of a 90% butyl acetate solution of an equimolar addition reaction product of isophorone diisocyanate and 2-hydroxyethyl acrylate, 0.02 part of pt-butylcatechol as a polymerization inhibitor, and urethane Dibutyltin dilaurate (0.02 part) was added to the reactor as a catalyst, and aged at 87 ° C. for 7 hours under dry air to obtain an unsaturated group-containing cellulose acetate butyrate solution. Next, the reaction temperature was raised to 115 ° C., and a mixed solution of the following polymerizable unsaturated monomer and polymerization initiator was added dropwise over 2 hours.

Butyl acetate 130 parts Methyl methacrylate 58.2 parts t-Butylperoxy-2-ethylhexanoate 2 parts After completion of dropping, 0.5 part of t-butylperoxy-2-ethylhexanoate and 20 parts of butyl acetate Was added dropwise over 1 hour and aged at 115 ° C. for 1 hour in a nitrogen atmosphere. A CAB graft acrylic resin solution having a nonvolatile content of 30% was obtained.
(Note 1) “CAB-381-0.5”: trade name, manufactured by Eastman Chemical Co., Ltd., cellulose acetate butyrate, butyl group content 38%, number average molecular weight 30,000.

Preparation of base paint Production examples 4-8
In the composition shown in Table 1, "aluminum paste MC-606" (trade name, manufactured by Asahi Kasei Metals Co., Ltd., aluminum paste, aluminum powder / mineral spirit / C9 grade aromatic hydrocarbon organic solvent weight ratio = 60/19 5 / 19.5, amine 1%) and the 55% acrylic resin solution obtained in Production Example 2 were stirred and dispersed, and a 25% “CAB551-0.2” solution (Note 2), obtained in Production Example 1. The obtained 70% polyester resin solution and 30% CAB graft acrylic resin solution were respectively blended, and butyl acetate was further added in the blending composition shown in the table, followed by stirring with a disper for about 20 minutes, and the metallic base paint (I-1) to (I-5) was prepared.

(Note 2) 25% “CAB551-0.2” solution: “CAB551-0.2” (trade name, manufactured by Eastman Chemical Co., Ltd., cellulose acetate butyrate, butyl group content 55%, number average molecular weight 30,000) ) Was adjusted to a 25% solids solution with butyl acetate.
Preparation of diluent Manufacturing Examples 9-26
Solvents were blended in the reaction vessel with the composition shown in Table 2, and stirred with a disper for about 10 minutes to prepare diluents (II-1) to (II-18).

Preparation of coating composition Example 1
With respect to 100 parts by weight of the metallic base paint (I-1), 100 parts by weight of the diluent (II-1) was mixed and stirred to obtain a paint composition.
Examples 2-12 and Comparative Examples 1-13
A coating composition was obtained in the same manner as in Example 1 except that the blending composition was as shown in Table 3 in Example 1.

“KAR Plush Gray” (trade name, Kansai Paint, Lacquer Primer Surfacer) was applied to the tinplate so that the dry film thickness was 40 μm, dried at 20 ° C. for 30 minutes, and then polished with # 400 water-resistant abrasive paper. did. On top of this, each of the coating compositions prepared in the above Examples and Comparative Examples was spray-coated so that the dry film thickness was 30 μm, dried at 20 ° C. for 10 minutes, and then the clear coating (Note 3) was applied to the coating surface. Was spray-coated to a dry film thickness of 40 μm and dried at a temperature of 20 ° C. for 24 hours to obtain a test coated plate. The following performance test was performed on the test coating plate before and after applying the clear paint. The results are shown in Table 3.

(Note 3) Clear paint: “Letane PG Multi-Clear HX (Q) Base” (Kansai Paint Co., Ltd., hydroxyl-containing acrylic resin-containing clear paint) 100 parts by weight “Letane PG Multi-Clear HX Standard Curing Agent” (Kansai Made by Paint Co., Ltd. (Hexamethylene diisocyanate curing agent) 50 parts by weight was diluted with diluent (II-1) for 13 to 14 seconds (Ford cup # 4/25 ° C.) and adjusted to viscosity. .
(* 1) Dryability Each of the above coating compositions is applied to a glass plate with a doctor blade in a constant temperature and humidity chamber at a temperature of 20 ° C. and a humidity of 75% so that the coating film thickness is 100 μm, and touched with a finger. The touch drying time until the paint did not stick to the finger was measured. The results were evaluated as follows.
A: Drying time less than 10 minutes, O: Drying time 10 or more and less than 12 minutes, Δ: 12 or more and less than 15 minutes, X: 15 minutes or more.
(* 2) Fukimura The orientation state of the pigment in the coating film of the test coating plate before applying the clear paint was visually observed. The results were evaluated as follows.
A: No unevenness, O: Slightly unevenness but practical level, Δ: Slightly unevenness, X: Unevenness is remarkable.
(* 3) Modimura The orientation state of the pigment in the coating film of the test coating plate coated with the clear paint and dried was visually observed. The results were evaluated as follows.
A: No unevenness, O: Slightly unevenness but practical level, Δ: Slightly unevenness, X: Unevenness is remarkable.
(* 4) Adhesion Cross-cut the test coating plate coated with a clear paint and dried in a 20 ° C atmosphere so that it reaches the substrate with a knife on the diagonal of the coating plate, and a peel test using an adhesive tape was performed. . The results were evaluated as follows.
○: No peeling, Δ: Slight peeling, x: Quite peeling.
(* 5) Corresponding to PRTR The contents of toluene and xylene contained in each coating composition obtained in the above examples and comparative examples were calculated and evaluated according to the following criteria. (○: PRTR regulated substance content less than 1%, x: PRTR regulated substance content of 1% or more)

Claims (6)

A coating composition comprising a metallic base paint (I) and a diluent (II), wherein the metallic base paint (I) comprises a cellulose derivative (A), an acrylic resin (B), a polyester resin (C) and an ester. at least one comprises an organic solvent (D) selected from the series organic solvents and ketone-based organic solvent, component a cellulose derivative (a), respectively (a), the total solids of component (B) and component (C) 5 to 75% by weight in weight, acrylic resin (B) in component (A), 5 to 90% by weight in total solid content of component (B) and component (C), polyester resin (C) in component ( a), component (B) and containing 5-45 wt% on total solids weight of component (C), the diluent (II) is an aliphatic hydrocarbon organic solvent, respectively (E), a diluent ( II) 5 to 90% by weight in the ester The organic solvent is 8 to 85% by weight, the ketone organic solvent is 2 to 35% by weight, the aliphatic hydrocarbon organic solvent (E) is alkylcyclohexane, and the blending amount of the diluent (II) is It is in the range of 20 to 250 parts by weight with respect to 100 parts by weight of the metallic base paint (I), and 90 to 590 weights of the ester organic solvent based on 100 parts by weight of the resin solid content in the metallic base paint (I). 100 to 700 parts by weight of an organic solvent (D) comprising 10 parts by weight and 10 to 110 parts by weight of a ketone organic solvent, and 20 to 340 parts by weight of an aliphatic hydrocarbon organic solvent (E). A paint composition. Cellulose derivative (A) is an esterified product of cellulose and a copolymer obtained by reacting a polymerizable unsaturated group-containing cellulose esterified product obtained by introducing a polymerizable unsaturated group into the esterified product and a polymerizable unsaturated monomer. The coating composition according to claim 1 , comprising (F) . The coating composition according to claim 2 , wherein the cellulose esterified product is cellulose acetate butyrate . A coating method comprising coating the coating composition according to any one of claims 1 to 3 on a surface to be coated. A coating method comprising: coating a coated surface with the coating composition according to any one of claims 1 to 3 , and then coating a clear coating on the coated surface. A coated article obtained by the coating method according to claim 4 or 5 .