JP5000860B2 - Paint composition - Google Patents

Description

  The present invention relates to a coating composition suitable for forming a coating film having gloss and polishing properties.

  Conventionally, acrylic lacquers, acrylic urethane paints, aminoacrylic resin paints, etc. for painting and repairing exterior panels and parts of automobiles, and painting and repairing industrial machines, buildings, structures, furniture (including steel), etc. In particular, in the field of automotive repair coatings, acrylic urethane coatings containing a hydroxyl group-containing acrylic resin and a polyisocyanate compound are mainly used from the viewpoint of room temperature drying and durability.

  For hydroxyl group-containing acrylic resins used in this field, styrene is specified from the point of gloss of the final coating film, and isobornyl (meth) acrylate or tricyclodecanyl (meth) acrylate is specified from the point of polishing May be copolymerized in quantity.

  For example, Patent Document 1 discloses that a weight average molecular weight of 2000 or more and less than 20000 is a monomer component composed of styrene, isobornyl (meth) acrylate, a hydroxyl group-containing polymerizable unsaturated monomer, and other polymerizable unsaturated monomers. The weight average molecular weight of which is composed of a monomer component consisting of a copolymer of styrene, isobornyl (meth) acrylate, a hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers is in the range of 20,000 to 100,000. A coating composition containing a copolymer and a curing agent is described.

  Patent Document 2 discloses at least one monomer selected from styrene, isobornyl (meth) acrylate and tricyclodecanyl (meth) acrylate, an alkyl ester having 8 to 20 carbon atoms of methacrylic acid, and the number of carbon atoms of acrylic acid. A monomer component composed of at least one monomer selected from alkyl esters of 4 to 20 and other polymerizable unsaturated monomers not having a carboxyl group is used as a constituent component, and the weight average molecular weight and hydroxyl group weight within a specific range. A coating composition containing a coalescence and a polyisocyanate is described.

  According to these coating compositions, a coating film having high gloss and excellent abrasiveness can be formed, and the anti-modulation resistance is excellent. Therefore, the coating composition can be suitably used as a repair clear coating.

  By the way, as the coating specifications using the top coating in this field, for example, one-coat painting finish in which only the base coat paint is applied and two-coat finish in which the clear paint is applied after the base coat paint is applied are known.

  Base coat paints for finishing one coat are usually made of a copolymer of styrene for the purpose of giving gloss to the paint film. For this reason, it is known that cellulose components such as cellulose acetate butyrate are often blended.

  In general, this styrene copolymer resin and cellulose acetate butyrate have very poor compatibility, and paints containing both of these components have a problem that the pigment dispersibility and storage stability (pigment easily aggregates) are reduced. It is necessary to prepare primary color paints for toning according to the base coat paint for finishing one coat and the base coat for finishing two coats.

  In recent years, 2-coat paint finishes are becoming mainstream in the self-repair field, but there is a great demand for 1-coat paint finishes for white paint colors, and a lineup of white base coat paints for 1-coat finishes is required. However, in the toning of the white paint color, it usually adjusts a slight yellowishness or blueness, and the primary color paint by the base coat paint for the 2-coat finish paint is used for the toning of the white base paint for the 1-coat finish. It was desired that it could be used as a seed.

  With regard to the above-mentioned problems, the applicant of the present invention disclosed in Patent Document 3 that a vinyl compound having a specific weight average molecular weight comprising a monomer component composed of styrene, a hydroxyl group-containing polymerizable unsaturated monomer, and other polymerizable unsaturated monomers as constituent components. A one-coat colored coating composition containing a resin, a specific cellulose acetate butyrate-modified vinyl resin and a polyisocyanate compound was proposed. According to this composition, even if a primary color paint based on a base coat paint for 2-coat finishing blended with cellulose acetate butyrate is used as a color type, a coating film having a high gloss feeling is formed without causing any trouble at the time of toning. However, depending on the type of primary color paint, there were cases where the abrasiveness when foreign matter adhered to the formed coating film was poor.

  By the way, the influence of volatile organic compounds on the environment has become a problem in recent years, and organic solvents such as toluene and xylene, which have been conventionally blended in the paint field, are regulated substances (for example, environmental pollutants). Emission transfer registration (POLLUTANT RELEASE AND TRANSFER REGISTER, etc.) is required, and it is required that these organic solvents be reduced or not substantially contained.

  Here, in the conventional paint composition, the organic solvent subject to regulation such as toluene and xylene is simply replaced with another organic solvent such as butyl acetate capable of dissolving the resin contained in the paint. There is a problem that the finish is not satisfactory, and there is a demand for development of environmentally friendly products as well as improvement of the above-described polishing properties.

JP 2000-273393 A JP 2001-2979 A JP 2003-13000 A

  An object of the present invention is to provide a coating composition which is suitable for forming a coating film having excellent gloss and polishing properties, and which is substantially free of regulated organic solvents.

As a result of intensive studies to solve the above problems, the present inventors have determined that the copolymerization ratio of a polymerizable unsaturated monomer having a styrene and a bridged alicyclic hydrocarbon group is a specific amount or more. The copolymerization ratio of the polymerizable unsaturated monomer containing a styrene and a bridged alicyclic hydrocarbon group containing a copolymer and a (meth) acrylate having an alkyl group having 1 to 3 carbon atoms as a copolymerization component is a specific amount. It has been found that a coating composition containing a hydroxyl group-containing copolymer, a cellulose derivative and a polyisocyanate, which is less than the above, forms a coating film having excellent gloss and polishing properties, and has reached the present invention.
That is, the present invention
1.
A coating composition containing a hydroxyl group-containing copolymer (A), a hydroxyl group-containing copolymer (B), a cellulose derivative (C) and a polyisocyanate (D), which constitutes the hydroxyl group-containing copolymer (A) The monomer component includes styrene (a), a polymerizable unsaturated monomer (b) having a bridged alicyclic hydrocarbon group, a hydroxyl group-containing polymerizable unsaturated monomer (c), and other polymerizable unsaturated monomers (d). And the total amount of styrene (a) and polymerizable unsaturated monomer (b) having a bridged alicyclic hydrocarbon group based on the total amount of the monomer components is 45% by mass or more, and the hydroxyl group-containing copolymer The weight average molecular weight of (A) is in the range of 2000 to 40000, and the monomer component constituting the hydroxyl group-containing copolymer (B) is styrene (a), hydroxyl group-containing polymerizable unsaturated monomer (c), carbon number. 1 to Of (meth) acrylate (e) having an alkyl group and other polymerizable unsaturated monomer (f), and the other polymerizable unsaturated monomer (f) is a polymer having a bridged alicyclic hydrocarbon group Polymerizable unsaturated monomer (b) having styrene (a) and bridged alicyclic hydrocarbon group based on the total amount of the monomer components, which may or may not contain polymerizable unsaturated monomer (b) A coating composition, wherein the total amount is less than 30% by mass, and the weight-average molecular weight of the hydroxyl group-containing copolymer (B) is in the range of 3000 to 50000,
2.
The other polymerizable unsaturated monomer (d) which is a monomer component constituting the hydroxyl group-containing copolymer (A) is a methacrylate having an alkyl group having 4 to 20 carbon atoms and / or carbon number as a part of the component. The coating composition according to claim 1, which comprises 4 to 20 acrylates.
3.
The other polymerizable unsaturated monomer (f) which is a monomer component constituting the hydroxyl group-containing copolymer (B) is a methacrylate and / or carbon number having an alkyl group having 4 to 20 carbon atoms as a part of the component. The coating composition according to claim 1, wherein the coating composition comprises 4 to 20 acrylates,
4).
The mixing ratio of the hydroxyl group-containing copolymer (A), the hydroxyl group-containing copolymer (B) and the cellulose derivative (C) is determined based on the total amount of the component (A), the component (B) and the component (C). Any one of 1 thru | or 3 whose content copolymer (A) is 5-49 mass%, hydroxyl-containing copolymer (B) is 50-94 mass%, and a cellulose derivative (C) is 1-45 mass%. The coating composition according to item 1,
5).
The coating composition according to any one of 1 to 4, further comprising at least one organic solvent (E) selected from the group consisting of an ester organic solvent, a ketone organic solvent, and an ether organic solvent,
6).
6. The coating composition according to any one of 1 to 5, further comprising an aliphatic hydrocarbon organic solvent (F),
7).
A coating method, characterized by applying the coating composition according to any one of items 1 to 6 to a surface to be coated,
About.

  According to the coating composition of the present invention, a coating film having excellent drying properties and high gloss can be formed, and the abrasiveness when foreign matter adheres to the coating film is also excellent. In addition, since the coating composition of the present invention is excellent in compatibility with various dilution thinners, the coating workability is good without using a regulated organic solvent, and a coating film with excellent finish is formed. be able to. When the coating composition of the present invention is a colored coating composition, since the coating is excellent in compatibility with various toning primary color coatings, it has excellent finish without causing problems during toning. A coating film can be formed.

Hydroxyl group-containing copolymer (A)
In the hydroxyl group-containing copolymer (A) in the present invention, the monomer component constituting the copolymer (A) is styrene (a), a polymerizable unsaturated monomer (b) having a bridged alicyclic hydrocarbon group. , A hydroxyl group-containing polymerizable unsaturated monomer (c) and other polymerizable unsaturated monomer (d).

  In the hydroxyl group-containing copolymer (A), the amount of styrene (a) used is 5 to 60% by mass, preferably 10 to 50% by mass, based on the monomer component constituting the hydroxyl group-containing copolymer (A). It is desirable from the viewpoint of the gloss of the coating film formed from the coating composition of the present invention to be within the range.

  Examples of the polymerizable unsaturated monomer (b) having a bridged alicyclic hydrocarbon group include compounds having a bridged alicyclic hydrocarbon group having 10 to 20 carbon atoms and a polymerizable unsaturated group. Typical examples of the bridged alicyclic hydrocarbon group having 10 to 20 carbon atoms include isobornyl group, tricyclodecanyl group and adamantyl group. Specific examples of the monomer include isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, adamantyl (meth) acrylate, 3,5-dimethyladamantyl (meth) acrylate, and 3-tetracyclododecyl (meth) acrylate. Etc., and can be used alone or in combination of two or more.

  The amount of the polymerizable unsaturated monomer (b) having a bridged alicyclic hydrocarbon group is 5 to 50% by mass, preferably 10 based on the monomer component constituting the hydroxyl group-containing copolymer (A). It is suitable from the point of the glossiness and abrasiveness of the coating film formed from the coating composition of this invention that it exists in the range of -40 mass%.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer (c) include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2,3-dihydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth). Monoesterified product of polyhydric alcohol and acrylic acid or methacrylic acid such as acrylate and polyethylene glycol mono (meth) acrylate; ring-opening polymerization of ε-caprolactone to monoesterified product of polyhydric alcohol and acrylic acid or methacrylic acid Compounds such as “Placcel FA-1”, “Placcel FA-2”, “Placcel FA-3”, “Plaxel FA-4”, “Plaxel FA-5”, “Plaxel FM-1”, “Plaxel FM” -2 "," Placcel FM-3 "," Plaxis FM-4 "," Placcel FM-5 "(all of which are manufactured by Daicel Chemical Co., Ltd., trade names) and the like can be mentioned. These can be used alone or in combination of two or more. Can be used in combination.

  The amount of the hydroxyl group-containing polymerizable unsaturated monomer (c) used is 5 to 40% by mass, preferably 10 to 30% by mass, based on the monomer component constituting the hydroxyl group-containing copolymer (A). It is desirable from the viewpoint of the hardness and finish of the coating film formed from the coating composition of the present invention.

  In the hydroxyl group-containing copolymer (A), the monomer component constituting the hydroxyl group-containing copolymer (A) can include other polymerizable unsaturated monomer (d) as a part of the component. Such other polymerizable unsaturated monomer (d) can be copolymerized with the above monomers (a), (b) and (c), and other than the monomers (a), (b) and (c). Examples of the polymerizable unsaturated monomer include alkyl groups having 1 to 3 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and isopropyl (meth) acrylate. (Meth) acrylate having n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate, n -Decyl methacrylate, n-dodecy Methacrylate having 4 to 20 carbon atoms such as methacrylate, n-tetradecyl methacrylate, n-hexadecyl methacrylate, n-octadecyl methacrylate, stearyl methacrylate; n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n -Pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-tetradecyl acrylate, n-hexadecyl acrylate , N-octadecyl acrylate, stearyl acrylate, “isostearyl acrylate” (manufactured by Osaka Organic Chemical Co., Ltd.), etc. An acrylate having a kill group; a (meth) acrylate having a cycloalkyl group such as cyclohexyl (meth) acrylate; a carboxyl group-containing polymerizable unsaturated monomer such as (meth) acrylic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate Epoxy group-containing polymerizable unsaturated monomers such as glycidyl (meth) acrylate and 3,4-epoxycyclohexylmethyl (meth) acrylate; N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) Aminoalkyl (meth) acrylates such as acrylate and N, N-dimethylaminopropyl (meth) acrylate; acrylamide, methacrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (Meth) acrylamide or a derivative thereof such as (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-methylol acrylamide, N-methylol acrylamide methyl ether, N-methylol acrylamide butyl ether; acrylonitrile, methacrylonitrile, Examples include vinyl acetate, Veova monomer (manufactured by Shell Chemical Co., Ltd.), vinyl toluene, and α-methylstyrene. These compounds can be used alone or in combination of two or more.

  In the present invention, the other polymerizable unsaturated monomer (d) contains a methacrylate having an alkyl group having 4 to 20 carbon atoms, particularly 4 to 8 carbon atoms, as a part of its components. It is desirable from the point of the abrasiveness of the coating film formed from.

  The amount of the methacrylate having an alkyl group having 4 to 20 carbon atoms is 1 to 20, preferably 3 to 15% by mass based on the monomer component constituting the hydroxyl group-containing copolymer (A). It is preferable from the point of the abrasiveness of the coating film formed from the coating composition of this invention.

  The other polymerizable unsaturated monomer (d) contains an acrylate having an alkyl group having 4 to 20 carbon atoms, particularly 6 to 18 carbon atoms. Desirable in terms of finish.

  The amount of the acrylate having an alkyl group having 4 to 20 carbon atoms is 1 to 15% by mass, preferably 1 to 10% by mass based on the monomer component constituting the hydroxyl group-containing copolymer (A). It is preferable from the point of the finishing property of the coating film formed from the coating composition of this invention.

  In the present invention, the hydroxyl group-containing copolymer (A) is a polymerizable unsaturated group having styrene (a) and a bridged alicyclic hydrocarbon group based on the total amount of monomer components constituting the copolymer (A). The total amount of the monomer (b) is 30% by mass or more, and particularly preferably 45% by mass or more. When the total amount of the monomer (a) and the monomer (b) is less than 30% by mass, the gloss and abrasiveness of the coating film formed from the coating composition of the present invention are insufficient, which is not preferable.

  In the present invention, the hydroxyl group-containing copolymer (A) has a weight average molecular weight of 2,000 to 40,000, preferably 6,000 to 15,000. It is suitable from the viewpoint of the finish of the coating film to be formed, and the coating film coated from the coating composition of the present invention that has a glass transition temperature in the range of 30 to 90 ° C., preferably 50 to 80 ° C. It is suitable from the point of abrasiveness.

  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.

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 / monomer total weight of 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. Using a sample synthesized with a molecular weight of about 50,000, the glass transition temperature of the sample is measured using a differential scanning thermal analysis “DSC-50Q type” (trade name, manufactured by Shimadzu Corporation). After removing the solvent by vacuum suction, measure the change in calorie in the range of -100 ° C to + 100 ° C at a rate of temperature rise of 3 ° C / min, and use the first baseline change point on the low temperature side. .

Hydroxyl group-containing copolymer (B)
In the hydroxyl group-containing copolymer (B) in the present invention, the monomer component constituting the hydroxyl group-containing copolymer (B) is styrene (a), a hydroxyl group-containing polymerizable unsaturated monomer (c), having 1 to 1 carbon atoms. 3 (meth) acrylate (e) having 3 alkyl groups and other polymerizable unsaturated monomer (f).

  The amount of styrene (a) used in the hydroxyl group-containing copolymer (B) is 5 or more and less than 30% by mass, preferably 5 to 5, based on the monomer component constituting the hydroxyl group-containing copolymer (B). It is preferable that it is in the range of 28% by mass from the viewpoint of the gloss of the coating film formed from the coating composition of the present invention and the compatibility with the cellulose derivative (C).

  The hydroxyl group-containing polymerizable unsaturated monomer (c) may be used alone or in combination of two or more of the monomers listed as the monomer (c) in the description of the hydroxyl group-containing copolymer (A). it can.

  The amount of the hydroxyl group-containing polymerizable unsaturated monomer (c) used is 5 to 40% by mass, preferably 10 to 30% by mass, based on the monomer component constituting the hydroxyl group-containing copolymer (B). It is preferable from the viewpoint of curability, coating film hardness, and finish of the coating film formed from the coating composition of the present invention.

  Examples of the (meth) acrylate (e) having an alkyl group having 1 to 3 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. Among them, it is preferable to use methyl methacrylate from the viewpoint of the abrasiveness of the formed coating film and the compatibility with the cellulose derivative (C).

  The amount of the (meth) acrylate (e) having an alkyl group having 1 to 3 carbon atoms is 5 to 40% by mass based on the monomer component constituting the hydroxyl group-containing copolymer (B), preferably From the point of compatibility between the gloss of the coating film formed from the coating composition of the present invention and the hydroxyl group-containing copolymer (B) and the cellulose derivative (C), being within the range of 10 to 30% by mass. Is preferred.

  In the hydroxyl group-containing copolymer (B), the monomer component constituting the hydroxyl group-containing copolymer (B) can contain other polymerizable unsaturated monomer (f) as a part of the component.

  Such other polymerizable unsaturated monomers (f) can be copolymerized with the monomers (a), (c) and (e), and are other than the monomers (a), (c) and (e). A polymerizable unsaturated monomer can be mentioned, and the polymerizable unsaturated monomer (b) having the bridged alicyclic hydrocarbon group may or may not be included.

  Specific examples of such other polymerizable unsaturated monomer (f) include, for example, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl. 4-20 carbon atoms such as methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate, n-decyl methacrylate, n-dodecyl methacrylate, n-tetradecyl methacrylate, n-hexadecyl methacrylate, n-octadecyl methacrylate, stearyl methacrylate Methacrylate having alkyl group; n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate , N-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-tetradecyl acrylate, n-hexadecyl acrylate, n-octadecyl acrylate, stearyl acrylate , “Isostearyl acrylate” (produced by Osaka Organic Chemical Co., Ltd.) and other acrylates having an alkyl group having 4 to 20 carbon atoms; isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, adamantyl (meth) acrylate, 3 Polymerizable unsaturated monomers having a bridged alicyclic hydrocarbon group such as 1,5-dimethyladamantyl (meth) acrylate and 3-tetracyclododecyl (meth) acrylate; cyclohexyl (meth) acrylate (Meth) acrylates having a cycloalkyl group such as carbonates; carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid and β-carboxyethyl acrylate; glycidyl (meth) acrylate, 3, Epoxy group-containing polymerizable unsaturated monomers such as 4-epoxycyclohexylmethyl (meth) acrylate; N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl Aminoalkyl (meth) acrylates such as (meth) acrylate; acrylamide, methacrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl ( (Meth) acrylamide or derivatives thereof such as acrylamide, N-methylolacrylamide, N-methylolacrylamide methyl ether, N-methylolacrylamide butyl ether; acrylonitrile, methacrylonitrile, vinyl acetate, Veova monomer (manufactured by Shell Chemical), vinyltoluene , Α-methylstyrene and the like. These compounds can be used alone or in combination of two or more.

  In the hydroxyl group-containing copolymer (B), the other polymerizable unsaturated monomer (f) contains a carboxyl group-containing polymerizable unsaturated monomer, and the finished coating film is formed from the coating composition of the present invention. From the viewpoint of adhesion and adhesion.

  Examples of the carboxyl group-containing polymerizable unsaturated monomer include (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like, and may be used alone or in combination of two or more. it can.

  The carboxyl group-containing polymerizable unsaturated monomer is used in an amount of 0.1 to 5% by mass, preferably 0.1 to 3% by mass, based on the monomer component constituting the hydroxyl group-containing copolymer (B). It is suitable from the point of the finish of the coating film formed from the coating composition of this invention, and adhesiveness.

  In the hydroxyl group-containing copolymer (B), the other polymerizable unsaturated monomer (f) contains a methacrylate having an alkyl group having 4 to 20 carbon atoms, particularly 4 to 8 carbon atoms. It is desirable from the point of the abrasiveness of the coating film formed from a coating composition.

  The methacrylate having an alkyl group having 4 to 20 carbon atoms is in the range of 5 to 60% by mass, preferably 20 to 50% by mass, based on the monomer component constituting the hydroxyl group-containing copolymer (B). Is preferable from the point of the abrasiveness of the coating film formed from the coating composition of this invention.

  In the hydroxyl group-containing copolymer (B), the other polymerizable unsaturated monomer (f) contains an acrylate having an alkyl group having 4 to 20 carbon atoms, particularly 6 to 18 carbon atoms. This is desirable from the viewpoint of the finish of the coating film formed from the coating composition.

  The acrylate having an alkyl group having 4 to 20 carbon atoms is formed from 1 to 20% by mass, preferably 3 to 15% by mass, based on the monomer component constituting the hydroxyl group-containing copolymer (B). It is preferable from the point of the finish of a coating film.

  In the present invention, the hydroxyl group-containing copolymer (B) is a polymerizable unsaturated group having styrene (a) and a bridged alicyclic hydrocarbon group based on the total amount of monomer components constituting the copolymer (B). The total amount of the monomer (b) is less than 30% by mass, and particularly preferably 28% by mass or less. When the total amount of the monomer (a) and the monomer (b) is 30% by mass or more, the compatibility between the resins contained in the coating composition of the present invention, particularly the hydroxyl group-containing copolymer (B) and the cellulose derivative (C). And the compatibility with the ink becomes insufficient, and the storage stability, toning workability, and finish of the formed coating film become insufficient.

  In the present invention, the hydroxyl group-containing copolymer (B) has a weight average molecular weight of 3000 to 50000, preferably 10,000 to 30000, and the finish of the coating film formed from the coating composition of the present invention. From the viewpoint of drying properties, etc.

  The glass transition temperature of the hydroxyl group-containing copolymer (B) is 20 to 80 ° C., preferably 30 to 70 ° C. The abrasiveness of the coating film formed from the coating composition of the present invention From the point of view, it is preferable.

  In the present invention, the polymerization method for producing the hydroxyl group-containing copolymer (A) and the hydroxyl group-containing copolymer (B) is not particularly limited, and is a polymerization method known per se, such as radical polymerization initiation. In the presence of an agent, 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.

  As the polymerization method by the solution polymerization method, for example, a method in which the monomer mixture is dissolved or dispersed in an organic solvent and heated in the presence of a polymerization initiator, usually at a temperature of about 80 ° C. to 200 ° C. with stirring. Can be mentioned. The reaction time is usually about 1 to 24 hours.

  As the polymerization initiator used in the production of the hydroxyl group-containing copolymer (A) and the hydroxyl group-containing copolymer (B) in the present invention, conventionally known ones used in the solution polymerization method can be used without limitation, For example, organic peroxides such as benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, t-butylperoxy 2-ethylhexanoate; azobisisobutyronitrile, azobis (2,4- And azo compounds such as dimethylvaleronitrile). These can be used alone or in combination of two or more.

  As the usage-amount of the said polymerization initiator, in the case of a hydroxyl-containing copolymer (A), it is 0.2- on the basis of the total mass of all the monomers used for manufacture of a hydroxyl-containing copolymer (A). In the case of the hydroxyl group-containing copolymer (B), the total mass of all monomers used for the production of the hydroxyl group-containing copolymer (B) is 12% by mass, preferably in the range of 0.3 to 10% by mass. In the range of 0.1 to 10% by mass, preferably 0.2 to 8% by mass.

Cellulose derivative (C)
In the present invention, the cellulose derivative (C) usually includes those in which the hydroxyl group of cellulose is esterified with an acid such as a fatty acid or nitric acid, such as nitrocellulose, cellulose acetate butyrate, cellulose acetate, cellulose acetate. Examples include 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. Preferably, the acetyl group content is generally 1 to 30% by mass and the butyl group content is generally 16 to 60% by mass. is there. Specifically, for example, “CAB-381-0.5”, “CAB-381-0.1”, “CAB-381-2.0”, “CAB-551-0.2”, “CAB-551”. -0.01 "(above, manufactured by Eastman Chemical Co., USA).

  The number average molecular weight of the cellulose acetate butyrate is in the range of 15,000 to 100,000, particularly 15,000 to 62,000, in terms of drying properties of the coating film formed from the coating composition of the present invention. To preferred.

  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 (“HLC8120GPC” manufactured by Tosoh Corporation) based on the number 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.

Polyisocyanate (D)
In the present invention, the polyisocyanate (D) is used as a curing agent component and reacts with the hydroxyl group in the hydroxyl group-containing copolymer (A) and the hydroxyl group-containing copolymer (B) to form a cured coating film. It can be formed. Examples of the polyisocyanate compound (B) include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4 (or 2,6) Cyclic aliphatic diisocyanates such as diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate Organic polyisocyanate itself such as triisocyanate or higher polyisocyanate such as lysine triisocyanate Each organic polyisocyanates with 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. Among these, hexamethylene diisocyanate isocyanurate is preferable. These may be used alone or in combination of two or more.

  The amount of the polyisocyanate compound (D) used is such that the isocyanate group (NCO) contained therein is based on the hydroxyl group (OH) in the hydroxyl group-containing copolymer (A) and the hydroxyl group-containing copolymer (B). The NCO / OH equivalent ratio is usually selected to be in the range of 0.2 to 2.0, preferably 0.5 to 1.5.

Coating composition The coating composition of the present invention comprises the hydroxyl group-containing copolymer (A), the hydroxyl group-containing copolymer (B), the cellulose derivative (C), and the polyisocyanate compound (D), and the hydroxyl group-containing copolymer. The blending ratio of copolymer (A), hydroxyl group-containing copolymer (B) and cellulose derivative (C) is based on the total amount of component (A), component (B) and component (C). The polymer (A) is 5 to 49% by mass, preferably 10 to 39% by mass.
The hydroxyl group-containing copolymer (B) is 50 to 94% by mass, preferably 60 to 89% by mass.
It is desirable that the cellulose derivative (C) is in the range of 1 to 45% by mass, preferably 1 to 30% by mass.

  The amount of the hydroxyl group-containing copolymer (A) is preferably in the range of 5 to 49% by mass from the viewpoint of finish of the coating film and improvement of gloss. The amount of the hydroxyl group-containing copolymer (B) is in the range of 50 to 94% by mass, with respect to color mixing stability with other primary color paints such as a base coat paint for 2-coat finishing, and drying properties of the coating film. It is preferable from the viewpoint. The amount of the cellulose derivative (C) is preferably in the range of 1 to 45% by mass from the viewpoints of workability such as drying properties and polishing properties of the coating film.

  In the present invention, the organic solvent contained in the coating composition is not particularly limited, and is desirably one that does not adversely affect the drying property of the formed coating film and the coating environment. Further, it is desirable to use an organic solvent capable of dissolving and compatibilizing the resin in the coating composition of the present invention, and specifically comprises an ester organic solvent, a ketone organic solvent, and an ether organic solvent. It is desirable to be at least one organic solvent (E) selected from the group.

  The organic solvent (E) preferably has a molecular weight in the range of 58 to 220, particularly 72 to 200. Examples of the ester organic solvent include ethyl acetate, butyl acetate, isobutyl acetate, 2-ethylhexyl acetate, and acetic acid. Examples of the ketone organic solvent include methyl ethyl ketone and methyl isobutyl ketone. Examples of the ether organic solvent include propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, Diethylene glycol monoethyl ether acetate can be mentioned, and these can be used alone or in combination of two or more. Among these, it is preferable to use an ester organic solvent from the viewpoint of storage stability of the coating composition.

  The organic solvent (E) is blended, for example, as a reaction solvent or a diluting solvent in the production of the hydroxyl group-containing copolymer (A) or the copolymer (B) contained in the coating composition or in a diluting thinner described later. be able to.

  The coating composition of the present invention can further contain an organometallic compound as a urethane curing catalyst, if necessary. Examples of the organometallic compound include tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, Dioctyltin oxide, dibutyltin fatty acid salt, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, fatty acid zincs, cobalt naphthenate, calcium octylate, copper naphthenate, tetra (2-ethylhexyl) titanate, etc. These may be used alone or in combination of two or more. These may be used in combination with known urethane curing catalysts such as tertiary amines and phosphoric acid compounds, if necessary. The amount used is usually in the range of 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, based on 100 parts by weight of resin solids in the paint.

  The coating composition of the present invention may be a clear coating composition or a colored coating composition.

  When the coating composition of the present invention is a colored coating composition, it can contain pigments such as colored pigments, bright pigments and extender pigments.

  Color pigments include white pigments such as titanium oxide; black pigments such as carbon black, acetylene black, lamp black, bone black, graphite, iron black, aniline black; yellow iron oxide, titanium yellow, monoazo yellow, condensed azo yellow, Yellow pigments such as azomethine yellow, bismuth vanadate, benzimidazolone, isoindolinone, isoindoline, quinophthalone, benzidine yellow, permanent yellow; orange pigments such as permanent orange; red iron oxide, naphthol AS azo red, ansanthrone, anthra Red pigments such as quinonyl red, perylene maroon, quinacridone red pigment, diketopyrrolopyrrole, watching red, permanent red; cobalt purple, quinacridone violet, dioxazine bio Tsu bets like purple pigments; cobalt blue, phthalocyanine blue, blue pigments such as vat blue; etc. green pigment such as phthalocyanine green and the like.

  Examples of the glitter pigment include aluminum powder, bronze powder, copper powder, tin powder, lead powder, zinc powder, iron phosphide, pearl metal coating mica powder, and mica iron oxide.

  Examples of extender pigments include talc, mica, barium sulfate, kaolin, calcium carbonate, clay, silica, quartz, and glass.

  The blending amount of the pigments can be adjusted as appropriate, and is generally in the range of 1 to 250 parts by weight, preferably 3 to 200 parts by weight with respect to 100 parts by weight of the resin solid content contained in the coating composition. It is desirable from the viewpoints of pigment dispersibility and coloring power of the paint.

  The coating composition of the present invention can contain an aliphatic hydrocarbon organic solvent (F) from the viewpoint of the finish of the formed coating film.

  The aliphatic hydrocarbon organic solvent (F) preferably has a high flash point and a high boiling point, for example, a linear, branched, or cyclic alkane having 5 to 12, particularly 6 to 10 carbon atoms, And mixtures thereof.

  In the present invention, a cyclic alkane is suitable as the aliphatic hydrocarbon organic solvent (F) from the viewpoints of solubility in a resin contained in the paint and finish of the coating film, and particularly, cyclohexane and alkylcyclohexane are preferred. Is preferred.

  Examples of the alkylcyclohexane include methylcyclohexane, ethylcyclohexane, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, propylcyclohexane, isopropylcyclohexane, 1-methyl, 2-ethylcyclohexane, 1- And methyl, 3-ethylcyclohexane, 1-methyl, 4-ethylcyclohexane, 1,2,3-trimethylcyclohexane, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane, etc. Or in combination of two or more.

  The blending amount of the aliphatic hydrocarbon organic solvent (F) can be adjusted as appropriate, and the aliphatic hydrocarbon organic solvent (F) is 10 to 450 mass% based on the resin solid content contained in the coating composition. , Preferably, it is blended to be in the range of 20 to 380% by mass.

  The coating composition of the present invention can be adjusted in viscosity with a diluted thinner in order to improve the coating workability in the coating stage and to improve the finish of the formed coating film.

  In the present invention, it is desirable that the aliphatic hydrocarbon organic solvent (F) is contained in the diluted thinner from the viewpoints of solubility in the resin in the paint and finish of the coating film.

  The blending amount of the aliphatic hydrocarbon organic solvent (F) in the diluted thinner is, for example, in the range of 5 to 90% by mass, preferably 10 to 80% by mass, and the color mixing stability of the diluted thinner and the formation coating. It is suitable from the viewpoint of the finish of the film.

  In the coating composition of the present invention, it is possible to form a coating film excellent in drying and finishing properties without using regulated organic solvents such as toluene and xylene. An organic solvent may be used.

  The coating composition of the present invention further includes a coating material such as an ultraviolet absorber, a light stabilizer, an antioxidant, a surface conditioner, a fluidity conditioner, a pigment dispersant, a non-aqueous dispersion resin, and an additive resin as necessary. Additives can be added as appropriate.

  The coating composition of the present invention obtained as described above is based on a component containing the hydroxyl group-containing copolymer (A), the hydroxyl group-containing copolymer (B) and the cellulose derivative (C) as a base coating, and is a polyisocyanate (D). It is desirable that it is provided as a two-component paint containing a hardener as a curing agent, mixed immediately before use, adjusted in viscosity with a diluted thinner as necessary, and used for coating.

  The coating method of the present invention is a coating method characterized by coating the coating composition 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. A multilayer coating film formed from a base coating film and a top clear coating film with a colored base coating can be exemplified, and a primer coating, an electrodeposition coating, an intermediate coating, etc. are applied under the base coating. A film may be provided as appropriate.

  Specific examples of the coated surface include, but are not limited to, vehicles such as passenger cars, trucks, buses, motorcycles, and trains; aircraft; buildings; home appliances.

  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.

  In addition, in the coating method of the present invention, a coating film excellent in gloss, abrasiveness, finish and the like can be formed only by coating the coating composition of the present invention. It is also possible to apply a conventionally known clear coating on the coating film formed from the composition.

Hereinafter, the present invention will be described in more detail with reference to examples. Here, “parts” and “%” mean “parts by mass” and “% by mass”, respectively.
Production of copolymer solution Production Example 1
The reactor is equipped with a thermometer, thermostat, stirrer, reflux condenser, and dropping pump, charged with 55 parts of butyl acetate, heated to 125 ° C. with stirring, and mixed with the following monomer mixture and polymerization initiator 3 It was dripped at a constant speed over time.
Styrene 40 parts isobornyl acrylate 25 parts isobutyl methacrylate 2 parts 2-ethylhexyl acrylate 5 parts 2-hydroxyethyl methacrylate 28 parts t-butylperoxy-2-ethylhexanoate 5.8 parts Then, a mixed solution of 0.5 parts of additional catalyst t-butylperoxy-2-ethylhexanoate and 3 parts of butyl acetate was added dropwise over 1.5 hours. The solution was aged for 1 hour to obtain a copolymer solution (A1). The obtained copolymer solution (A1) had a nonvolatile content of 60%, the copolymer had a weight average molecular weight of 12,000 and a glass transition temperature of 73 ° C.

Production Example 2
In the said manufacture example 1, the copolymer solution (A2) was obtained like the said manufacture example 1 except having set the dripped material as the following composition. The obtained copolymer solution (A2) had a nonvolatile content of 60%, a weight average molecular weight of 9000, and a glass transition temperature of 68 ° C.
Styrene 20 parts isobornyl acrylate 35 parts isobutyl methacrylate 11 parts 2-ethylhexyl acrylate 6 parts 2-hydroxyethyl methacrylate 28 parts t-butylperoxy-2-ethylhexanoate 6.3 parts Production Example 3
In the said manufacture example 1, the copolymer solution (A3) was obtained like the said manufacture example 1 except having set the dripped material as the following composition. The obtained copolymer solution (A3) had a nonvolatile content of 60%, the copolymer had a weight average molecular weight of 10,000 and a glass transition temperature of 75 ° C.
Styrene 30 parts isobornyl acrylate 30 parts isobutyl methacrylate 10 parts 2-ethylhexyl acrylate 2 parts 2-hydroxyethyl methacrylate 28 parts t-butylperoxy-2-ethylhexanoate 6.1 parts.

Production Example 4
The reactor is equipped with a thermometer, thermostat, stirrer, reflux condenser, and dropping pump, charged with 50 parts of butyl acetate, heated to 114 ° C. with stirring, and mixed with the following monomer mixture and polymerization initiator 3 It was dripped at a constant speed over time.
Styrene 15 parts methyl methacrylate 15 parts isobutyl methacrylate 39 parts 2-ethylhexyl acrylate 10 parts 2-hydroxyethyl methacrylate 20 parts methacrylic acid 1 part azobisisobutyronitrile 2.0 parts Next, a mixed solution of 0.5 part of an additional catalyst (t-butylperoxy-2-ethylhexanoate) and 7 parts of butyl acetate was added dropwise over 1 hour. After the addition was completed, the mixture was further aged at the same temperature for 1 hour. A copolymer solution (B1) was obtained. The obtained copolymer solution (B1) had a nonvolatile content of 52%, the copolymer had a weight average molecular weight of 15000 and a glass transition temperature of 52 ° C.
Production Example 5
In the said manufacture example 4, the copolymer solution (B2) was obtained like the said manufacture example 4 except having set the dripped material as the following composition. The resulting copolymer solution (B2) had a nonvolatile content of 52%, the copolymer had a weight average molecular weight of 20000 and a glass transition temperature of 62 ° C.
Styrene 10 parts methyl methacrylate 25 parts isobutyl methacrylate 39 parts 2-ethylhexyl acrylate 5 parts hydroxyethyl methacrylate 20 parts methacrylic acid 1 part azobisisobutyronitrile 2.3 parts Production Example 6
In Production Example 4, a copolymer solution (B3) was obtained in the same manner as in Production Example 4 except that the dropped product had the following composition. The obtained copolymer solution (B3) had a nonvolatile content of 52%, the copolymer had a weight average molecular weight of 25,000 and a glass transition temperature of 42 ° C.
Styrene 25 parts methyl methacrylate 12 parts isobutyl methacrylate 24 parts 2-ethylhexyl acrylate 18 parts hydroxyethyl methacrylate 20 parts methacrylic acid 1 part azobisisobutyronitrile 1.7 parts.

Production Example 7
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump, 60 parts of xylene were charged, and the temperature was raised to 125 ° C. while stirring, and a mixture of the following monomer and polymerization initiator was added. Using a dropping pump, it was dropped at a constant rate over 3 hours. After completion of the dropwise addition, the reaction was terminated by aging for 2 hours at the same temperature. The obtained copolymer solution (C1) was a uniform transparent solution having a nonvolatile content of 60%. The copolymer had a weight average molecular weight of about 9,000 and a glass transition temperature of 44 ° C.
Styrene 40 parts isobornyl acrylate 20 parts 2-ethylhexyl acrylate 13.25 parts 2-hydroxyethyl methacrylate 19 parts 2-hydroxyethyl acrylate 7.5 parts acrylic acid 0.25 parts t-butylperoxy 2-ethylhexanoate 6.5 parts Production Example 8
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a thermostat, and a dropping pump, 80 parts of xylene are charged, the temperature is raised to 115 ° C. while stirring, and a mixture of the following monomer and polymerization initiator is added: Using a dropping pump, it was dropped at a constant rate over 3 hours. After completion of the dropwise addition, the reaction was terminated by aging for 2 hours at the same temperature. The obtained copolymer solution (C2) had a nonvolatile content of 55%, the copolymer had a weight average molecular weight of about 30,000 and a glass transition temperature of 45 ° C.
Styrene 40 parts Isobornyl acrylate 20 parts n-Butyl acrylate 20.75 parts 2-Hydroxyethyl methacrylate 19 parts Acrylic acid 0.25 parts t-Butylperoxy 2-ethylhexanoate 1.7 parts Production Example 9
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump, 60 parts of xylene were charged, and the temperature was raised to 125 ° C. while stirring, and a mixture of the following monomer and polymerization initiator was added. Using a dropping pump, it was dropped at a constant rate over 3 hours. After completion of the dropwise addition, the reaction was terminated by aging for 2 hours at the same temperature. The obtained copolymer solution (C3) had a non-volatile content of 60%, the weight average molecular weight of the copolymer was about 9,000, and the glass transition temperature was 43 ° C.
Styrene 40 parts isobornyl acrylate 20 parts 2-ethylhexyl acrylate 13.5 parts 2-hydroxyethyl methacrylate 19 parts 2-hydroxyethyl acrylate 7.5 parts t-butyl peroxyhexanoate 6.5 parts.

Production Example 10
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a thermostat, and a dropping pump, 60 parts of xylene were charged, the temperature was raised to 115 ° C. while stirring, and a mixture of the following monomer and polymerization initiator was added. Using a dropping pump, it was dropped at a constant rate over 3 hours. After completion of the dropwise addition, the reaction was terminated by aging for 2 hours at the same temperature. The obtained copolymer solution (C4) had a nonvolatile content of 55%, the copolymer had a weight average molecular weight of about 26000, and a glass transition temperature of 44 ° C.
Styrene 40 parts Isobornyl acrylate 20 parts n-butyl acrylate 21 parts 2-hydroxyethyl methacrylate 19 parts t-butyl peroxyhexanoate 1.7 parts Production Example 11
The reactor is equipped with a thermometer, thermostat, stirrer, reflux condenser, and dropping pump, charged with 60 parts of xylene, heated to 125 ° C. with stirring, and dropped monomer mixture consisting of the following monomers and polymerization initiator: The solution was dropped at a constant rate over 4 hours. And after completion | finish of dripping, it age | cure | ripened at the same temperature for 1 hour, Then, the mixed solution of additional catalyst (t-butylperoxy-2-ethylhexanoate) 0.5 part and butyl acetate 10 parts was dripped over 1 hour. After completion of the dropping, the mixture was further aged at the same temperature for about 2 hours to obtain a copolymer solution (C5) having a nonvolatile content of 60%. The copolymer had a weight average molecular weight of 9000 and a glass transition temperature of 55 ° C.
Styrene 30 parts Isobornyl acrylate 20 parts 2-ethylhexyl acrylate 10 parts n-butyl acrylate 8.4 parts 2-hydroxyethyl methacrylate 28 parts Succinic anhydride 0.7 parts t-butylperoxy-2-ethylhexanoate 6 Department.

Production of cellulose acetate butyrate modified copolymer solution Production Example 12
The reactor was equipped with a thermometer, thermostat, stirrer, reflux condenser, and dropping pump, and the following components were charged into it.
50 parts of butyl acetate “CAB-551-0.01” (trade name, manufactured by Eastman Kodak Company) 50 parts The above mixture was heated in a nitrogen gas atmosphere and heated to 100 ° C. over about 1 hour. After confirming that cellulose acetate butyrate was completely dissolved at 100 ° C., a mixture of the following monomer mixture and polymerization initiator was dropped into a cellulose acetate butyrate solution maintained at 100 ° C. over 3 hours.
Styrene 10 parts isobornyl methacrylate 15 parts methyl methacrylate 2.5 parts t-butyl methacrylate 2 parts i-butyl methacrylate 10.5 parts hydroxyethyl methacrylate 5 parts hydroxybutyl acrylate 5 parts butyl acetate 50 parts benzoyl peroxide 2 parts 30 minutes after the completion, 0.5 part of azobisisobutylnitrile was added, and the reaction was completed by aging for 2 hours in a nitrogen atmosphere. The obtained cellulose acetate butyrate-modified copolymer solution (C6) was a uniform transparent solution having a nonvolatile content of 50%.

Production of pigment dispersion paste Production Examples 13 to 18
The copolymer solution shown in Table 1 was blended in the blending amounts shown in Table 1, and “TIPAQUE CR95” (trade name, manufactured by Ishihara Sangyo Co., Ltd., titanium oxide pigment), “BYK161” (trade name, manufactured by BYK-chemie) , Pigment dispersant), “Fronon ED-1000” (trade name, manufactured by Kyoeisha, pigment settling inhibitor) and butyl acetate were added in the formulation shown in Table 1, and stirred with a disper for about 20 minutes, and then dispersed with a sand mill. Each pigment dispersion paste was obtained.

Preparation of 1-coat finish white paint Examples 1-20 and Comparative Examples 1-5
Each component is prepared by mixing the ingredients shown in Table 2 below, and the primary color paint for toning (Note 5) and curing agent (Note 6) are blended in accordance with Table 2 to prepare the toned white paint. Was created respectively. The storage stability of the white paint was evaluated by the following method and standard.

  Each white paint is diluted with thinner thinner I (Note 7) or II (Note 8) in the amount shown in Table 2 to adjust the viscosity, and at 20 ° C on a process board coated with white paint for new cars. Spray coating was performed to obtain a dry film thickness of 60 μm to obtain each test coated plate. About these, finish property, drying property, and polishing were evaluated by the following methods and standards. The evaluation results are shown in Table 2.

Evaluation criteria (* 1) Storage stability: Each main agent was enclosed in a 1/4 L round can, stored at 40 ° C. for 4 weeks, and the state was observed. (○: Good, Δ: Slight pigment sedimentation, ×: Significant pigment sedimentation)
(* 2) Finishing property: The gloss of the coating film was visually determined. (○: Good with gloss, △: Slightly inferior to gloss, ×: Very low gloss)
(* 3) Drying: In a constant temperature and humidity chamber with a temperature of 20 ° C. and a humidity of 75%, the glass plate is coated with a doctor blade so that the coating film thickness is 100 μm, and the paint does not stick to the finger when touched with a finger. (○: Drying time less than 10 minutes, Δ: 10 or more and less than 15 minutes, ×: 15 minutes or more)
(* 4) Abrasiveness: After drying the test coating plate at 60 ° C. for 30 minutes, the coating surface of the test plate after 2 hours was applied with a fine polishing compound on a towel buff and polished for 30 seconds. The scratches and finished gloss were visually evaluated. (○: almost no scratches, good gloss, Δ: some scratches are observed, ×: many scratches are seen, gloss reduction

(Note 1) 25% CAB551-0.2 solution: 25% butyl acetate solution of "CAB551-0.2" (manufactured by Eastman Chemical Co., cellulose acetate butyrate, butyl group content 55%, number average molecular weight 60000) (Note 2) 25% CAB551-0.01 solution: 25% butyl acetate solution of “CAB551-0.01” (manufactured by Eastman Chemical Co., cellulose acetate butyrate, butyl group content 55%, number average molecular weight 16000) (Note 3) 25% CAB381-0.1 solution: 25% butyl acetate solution of “CAB381-0.1” (manufactured by Eastman Chemical Co., Ltd., cellulose acetate butyrate, butyl group content 38%, number average molecular weight 20000) (Note 4) “STANN BL”: Sankyo Co., Ltd., dibutyltin dilaurate (Note 5) “Letane” G Hybrid Eco-No.361 ": Base coat paint for 2-coat finishing, Kansai Paint Co., Ltd., yellow primary color, cellulose acetate butyrate blended, less than 1% blended toluene and xylene (Note 6)" Duranate TPA100 ": Asahi Kasei Manufactured, isocyanurate type of hexamethylene diisocyanate having a non-volatile content of 100% and an NCO content of 23.1% (Note 7) diluted thinner I: butyl acetate / methyl ethyl ketone / methyl cyclohexane / dimethyl cyclohexane (mass ratio) = 50/10/20 / 20 mixed solvent (Note 8) diluted thinner II: xylene / butyl acetate / shell sol A (Aromatic petroleum solvent, manufactured by Shell Chemical Co., Ltd.) (mass ratio) = 60/20/20 mixed solvent

Claims (7)

A coating composition containing a hydroxyl group-containing copolymer (A), a hydroxyl group-containing copolymer (B), a cellulose derivative (C) and a polyisocyanate (D), which constitutes the hydroxyl group-containing copolymer (A) The monomer component includes styrene (a), a polymerizable unsaturated monomer (b) having a bridged alicyclic hydrocarbon group, a hydroxyl group-containing polymerizable unsaturated monomer (c), and other polymerizable unsaturated monomers (d). And the total amount of styrene (a) and polymerizable unsaturated monomer (b) having a bridged alicyclic hydrocarbon group based on the total amount of the monomer components is 45% by mass or more, and the hydroxyl group-containing copolymer The weight average molecular weight of (A) is in the range of 2000 to 40000, and the monomer component constituting the hydroxyl group-containing copolymer (B) is styrene (a), hydroxyl group-containing polymerizable unsaturated monomer (c), carbon number. 1 to Of (meth) acrylate (e) having an alkyl group and other polymerizable unsaturated monomer (f), and the other polymerizable unsaturated monomer (f) is a polymer having a bridged alicyclic hydrocarbon group Polymerizable unsaturated monomer (b) having styrene (a) and bridged alicyclic hydrocarbon group based on the total amount of the monomer components, which may or may not contain polymerizable unsaturated monomer (b) The total amount of is less than 30 mass%, and the weight average molecular weight of this hydroxyl-containing copolymer (B) exists in the range of 3000-50000, The coating composition characterized by the above-mentioned. The other polymerizable unsaturated monomer (d) which is a monomer component constituting the hydroxyl group-containing copolymer (A) is a methacrylate having an alkyl group having 4 to 20 carbon atoms and / or carbon number as a part of the component. The coating composition according to claim 1, which comprises 4 to 20 acrylates. The other polymerizable unsaturated monomer (f) which is a monomer component constituting the hydroxyl group-containing copolymer (B) is a methacrylate and / or carbon number having an alkyl group having 4 to 20 carbon atoms as a part of the component. The coating composition according to claim 1, which comprises 4 to 20 acrylates. The mixing ratio of the hydroxyl group-containing copolymer (A), the hydroxyl group-containing copolymer (B) and the cellulose derivative (C) is determined based on the total amount of the component (A), the component (B) and the component (C). The content copolymer (A) is 5 to 49 mass%, the hydroxyl group-containing copolymer (B) is 50 to 94 mass%, and the cellulose derivative (C) is 1 to 45 mass%. 2. The coating composition according to item 1. The coating composition according to any one of claims 1 to 4, further comprising at least one organic solvent (E) selected from the group consisting of an ester organic solvent, a ketone organic solvent, and an ether organic solvent. The coating composition according to any one of claims 1 to 5, further comprising an aliphatic hydrocarbon organic solvent (F). A coating method comprising coating the coating composition according to any one of claims 1 to 6 on a surface to be coated.