JPH0717721B2 - Resin composition for paint - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for paints which is useful as a binder for paints that can be directly applied (1-Coat) to an adherend such as plastics and metals without a primer. It is about things.

[0002]

2. Description of the Related Art In recent years, in the automobile industry, automobile parts have been rapidly changed to plastics in view of weight reduction of vehicle bodies, rust prevention measures, and freedom of design. Plastic materials used for automobiles include non-polar polyolefin resins such as polypropylene and polyethylene; polyamide resins, polybutylene terephthalate resins, polyurethane resins, unsaturated polyester resins, FRP, polycarbonate resins and their mixed plastics, reinforced plastics, etc. Is mentioned.

Many of these plastics are generally difficult to paint, and in particular, non-polar polyolefin resin is applied through complicated working steps such as pretreatment (oxidation treatment) -undercoating-topcoating. The same applies to building resins other than automobiles, package resins for home appliances, steel aggregates,
The same can be said for steel plates and the like, and the undercoat and the overcoat are applied to the adherend in a plurality of steps.

[0004]

A coating material for a polyolefin-based resin base material having a particularly difficult coating property will be described. Paints based on chlorinated polyolefin resins are polyethylene,
Although it adheres to polypropylene temporarily, it has a serious problem in terms of long-term stability, coating workability, and the like. That is, when used for a long period of time, chlorine is desorbed with time to easily turn the coating film into yellow or deteriorate, and there is a problem with the weather resistance of the coating film, and it has not been put to practical use as a coating resin. Even if the polyolefin resin is pretreated (physical treatment such as surface polishing, chromic acid mixture treatment, solvent treatment, plasma treatment, corona treatment, etc.) before any coating, it is still possible to create a coating with good adhesion. Have difficulty.

As a method for improving the above-mentioned problems, particularly weather resistance, (1) chlorinated polyolefin resin or unsaturated polycarboxylic acid or its acid anhydride-modified chlorinated polyolefin,
Paints blended with general-purpose acrylic resins have been proposed (Japanese Patent Laid-Open Nos. 57-198764 and 60-12356).
No. 5, Japanese Patent Publication No. 61-860), the compatibility between the chlorinated polyolefin and the acrylic resin is not sufficient, and the weather resistance improving effect is also insufficient. (2) A coating resin obtained by polymerizing an acrylic monomer in the presence of a chlorinated polyolefin resin (JP-A-56-50971).
(3) Japanese Patent Publication No. 61-12940) (3) An epoxy compound having two or more epoxy groups per molecule is obtained by polymerizing a monomer mixture containing a functional group-containing acrylic monomer in the presence of a chlorinated polyolefin. Paint containing epoxy resin (JP-A-56-5)
No. 0971) (4) A coating material containing an unsaturated polycarboxylic acid or a chlorinated polyolefin modified with an acid anhydride thereof and an epoxy compound or an epoxy resin having two or more epoxy groups per molecule (JP-A-60 No. 22383), but the improvement effect is insufficient and there is a problem in the weather resistance of the coating film.

[0006]

Means for Solving the Problems The present invention provides a maleic anhydride graft-modified styrene / butadiene / styrene block copolymer in which an hydrogenated product (A) is dissolved in an inert solvent having 1 to 8 carbon atoms. It is intended to provide a resin composition for a coating obtained by polymerizing a vinyl monomer (B) containing 50% by weight or more of an acrylic acid ester or a methacrylic acid ester having an alkyl group or a cyclohexyl group. [However, the weight ratio of the component (A) and the component (B) (A /
B) is 2/8 to 7/3. ]

Methods for making styrene-butadiene-styrene block copolymers are well known to those skilled in the art, and the typical procedure is US Pat. 3265765 (196
(August 9, 2006). By hydrogenating the intramolecular double bond of the block copolymer of styrene and butadiene of this block copolymer, an elastomer having improved thermal stability can be obtained. The production of such a hydrogenated block copolymer is described in, for example, Japanese Patent Publication No.
2-8704, Japanese Patent Publication No. 43-6636, Japanese Patent Publication No. 45
No. 20504, Japanese Patent Publication No. 48-3555 and the like. Further, some compositions using these hydrogenated products have been proposed, for example, in Japanese Patent Laid-Open Nos. 50-14742, 52-65551, and JP-B-60-4225. Discloses a composition obtained by blending a hydrogenated styrene / conjugated diene-block copolymer with a hydrocarbon oil, a rosin ester adhesive and an α-olefin polymer, a wax, an ethylene / vinyl acetate copolymer and the like. . Such hydrogenated product is S
Kr from hell Chemical Company
aton G- with a grade name, for example, # 165
It is sold under the code name of 2.

The modification with maleic acid or its anhydride is described, for example, in JP-A-61-292743, and maleic anhydride and radicals are added to the hydrogenated product of the above-mentioned styrene / butadiene / styrene block copolymer. A method of reacting the polymerization initiator in a melted state in an extruder, and a method of heating and dissolving these in an organic solvent such as toluene, xylene, chlorobenzene, and the like are preferable.

The graft amount of maleic anhydride is 0.01
Used in the range of -10%. Maleic anhydride depends on the adhesion of the coating film to the adherend and the crosslinkability of the coating film. Examples of the inert organic solvent which dissolves the hydrogenated styrene / butadiene / styrene block copolymer modified with maleic anhydride graft are aromatic hydrocarbons such as toluene, xylene and chlorobenzene, and ketones such as methyl ethyl ketone and methyl isobutyl ketone. , Esters such as ethyl acetate and butyl acetate, chlorinated solvents such as carbon tetrachloride, tetralin,
Mineral spirits and the like and mixed solvents thereof are used. This inert organic solvent is capable of dissolving the maleic anhydride graft-modified hydrogenated styrene / butadiene / styrene block copolymer and the vinyl monomer of the component (B), and comprises the components (A) and (B). It is used in an amount sufficient for dissolution, and the amount is usually used in a proportion of 50 to 2,000 wt% of the sum of both.

Component (B): The vinyl monomer of component (B) is mainly composed of an acrylic acid ester having a C 1-8 alkyl group or a cyclohexyl group or its methacrylic acid ester equivalent. Therefore, if necessary, another vinyl monomer such as α, β-unsaturated carboxylic acid or its acid anhydride, a vinyl monomer having a hydroxyl group, styrene, acrylonitrile, divinylbenzene, butanediol diacrylate, and acrylamide may be added. weight%
You may contain in the following ratios.

Examples of the acrylate ester having a C1-8 alkyl group or cyclohexyl group or its methacrylic acid ester equivalent include methyl acrylate,
Ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t acrylate
-Butyl, cyclohexyl acrylate and their methacrylic acid ester equivalents can be used. These acrylates contribute to the improvement of the weather resistance of the obtained film, the adhesion to the substrate, and the hardness.

As the α, β-unsaturated carboxylic acid or its acid anhydride, acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, crotonic acid, fumaric acid, maleic anhydride are used. Also, maleic acid,
When it is a polybasic acid such as fumaric acid, its half alkyl ester may be used. These unsaturated acids are (B)
It is used in a proportion of 0.1 to 10% by weight in the components. Also,
It is used in a proportion of 0.01 to 5% by weight of the sum of the components (A) and (B).

Examples of vinyl monomers having a hydroxyl group include hydroxyethyl acrylate, hydroxypropyl acrylate, butanediol monoacrylate, polyethylene glycol monoacrylate, their methacrylate equivalents, N-methylol acrylamide, allyl alcohol, hydroxyethyl vinyl ether and hydroxy. Examples include ethyl butyl maleate and ε-caprolactone modified acrylate. The vinyl monomer having these hydroxyl groups is 0.5 to 20% by weight in the component (B), (A)
It is used in a proportion of 0.1 to 10% by weight of the sum of the component and the component (B). These unsaturated acids and vinyl monomers having a hydroxyl group enable the crosslinking reaction of hydrogenated styrene / butadiene / styrene copolymer.

Polymerization: Polymerization is carried out by dissolving a polymerization initiator in a liquid prepared by dissolving a hydrogenated styrene / butadiene / styrene block copolymer modified with maleic anhydride in an inert organic solvent. It is carried out by dropping the body all at once or gradually dropping it and heating it at 65 to 150 ° C. under stirring. The polymerization time is 1 to 24 hours.

Examples of the polymerization initiator include organic peroxides and azonitriles. Organic peroxides include
Alkyl peroxide, aryl peroxide, acyl peroxide, aroyl peroxide, ketone peroxide, peroxycarbonate, peroxycarboxylate and the like are included. Alkyl peroxides are diisopropyl peroxide, ditertiary butyl peroxide, tert-butyl hydro-peroxide, aryl peroxides are dicumyl peroxide, cumyl hydroperoxide, acyl peroxides are dilauroyl peroxide, alloys. Examples of luperoxide include dibenzoyl peroxide, and examples of ketone peroxide include methyl ethyl ketone peroxide and cyclohexanone peroxide. Examples of azonitriles include azobisisobutyronitrile and azobisisopropionitrile.

The maleic anhydride graft-modified hydrogenated styrene / butadiene / styrene block copolymer as the component (A) is a component that contributes to the adhesion of the coating film to the adherend, flex resistance, and impact resistance. , The polymer of component (B) is the hardness of the coating film,
It has a great influence on solvent resistance, weather resistance, abrasion resistance, etc., and (A) / (B) on the balance of all coating film performance.
Is used in a ratio of 2/8 to 7/3 (weight ratio). (A) /
If (B) is less than 2/8, the adhesion to the substrate will be too poor. On the other hand, if it exceeds 7/3, solvent resistance and gasoline resistance deteriorate.

Resin for coating: The resin obtained by the above polymerization is a hydrogenated styrene / butadiene / styrene block copolymer, a copolymer of vinyl monomers, a vinyl monomer graft hydrogenated styrene / butadiene / styrene block copolymer. It is a polymer alloy in which polymers and the like are homogeneously mixed. The product obtained by the polymerization is a solution in which the coating resin is dissolved in an organic solvent. Therefore, a pigment, a dispersant, a leveling agent, a cross-linking agent and the like may be added thereto to prepare a coating. In addition, after removing the organic solvent, a new organic solvent, pigment, dispersant, etc. may be added to form a coating, or a necessary amount of the organic solvent for viscosity adjustment may be partially removed from the resin solution. Alternatively, it may be added to the above resin solution, and then a pigment or the like may be added to form a coating material.

One-coat paint: An example of the composition of the paint that can be directly applied to the substrate is shown below. (A) 100 parts by weight of the coating resin of the present invention (b) 0 to 50 parts by weight of a crosslinking agent (c) 100 to 5,000 parts by weight of an organic solvent that dissolves the resins of the above-mentioned components (a) and (b) ( d) Pigment 10 to 300 parts by weight (e) Other optional component 0 to 10 parts by weight.

However, the above-mentioned crosslinking agent (b) is added for the purpose of improving the hardness and gasoline resistance of the coating film, and is a resin having a functional group that reacts with a carboxyl group or a hydroxyl group. Polyepoxide having an epoxy group; polyurethane resin having an isocyanate group, polyester resin, blocked polyisocyanate; acrylic resin having a reactive functional group (—OH, —COOH), amino resin and the like can be used.

Specific examples of the cross-linking agent include (1) self-reactive compounds such as methanol, ethanol and n.
-Amino resins such as melamine resins or urea resins modified with alcohols such as butanol and isobutanol, and polymerizable unsaturated group-containing compounds (for example, trimethylolpropane triacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, etc. Polyfunctional acrylate; Epoxy acrylate or methacrylate obtained by esterifying epoxy group of epoxy compound with acrylic acid or methacrylic acid; Polyurethane acrylate or methacrylate obtained by reacting polyisocyanate compound described later with acrylate or methacrylate having a hydroxyl group; Melamine acrylate or methacrylate obtained by reacting an acrylate or methacrylate having a hydroxyl group with a carboxyl group, hydroxyl group Amino group, an acrylic resin obtained by copolymerizing an acrylic monomer having a functional group such as a methylol group.

(2) Polyisocyanate compounds (for example, aromatic diisocyanates or fats such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate and cyclohexane 1,4-diisocyanate). Group diisocyanates, and their adducts with diols, triols, etc., polyisocyanates such as chain trimers in the form of burette bonds, cyclic trimers) and all or part of the isocyanate groups contained in the aforementioned polyisocyanate compounds Examples thereof include blocked isocyanate compounds in a form blocked with a blocking agent such as lower alcohol, ε-caprolactam, methylethiketoxime, diethylmalonate, and phenol.

Further, (3) the epoxy compound is a compound containing one or more, especially two or more epoxy groups in the molecule and a mixture thereof, for example, 2,2-bis (4-hydroxyphenyl) propane. (Bisphenol A), bis (4-hydroxyphenyl) methane, 1,1
-Polyglycidyl ethers of polyhydric phenols such as bis (4-hydroxyphenyl) ethane, polyglycidyl ethers of polyhydric alcohols such as glycerin, pentaerythritol, trimethylolpropane, diglycidyl ethers of polyalkylene polyethers, polycarboxylic acids Examples thereof include diglycidyl ester of acid, so-called dimer acid.

Further, an olefin, for example, an epoxy compound obtained by oxidizing polybutadiene with a peracid, an acrylic epoxy compound obtained by copolymerizing with glycidyl acrylate or glycidyl methacrylate, and a phenol novolak obtained by a reaction of phenol and formalin. Type epoxy compounds and the like, and modified products thereof.

These cross-linking agents are used alone or in admixture of two or more. Further, these cross-linking agents may be mixed with an active hydrogen-containing resin such as an acrylic resin, a polyester resin or a polyurethane resin having a functional group such as a carboxyl group, a hydroxyl group, an amino group or an imino group which chemically reacts.

As the organic solvent of the component (c), those exemplified as the solvent for dissolving the hydrogenated styrene / butadiene / styrene block copolymer can be used. As the pigment of the component (d), inorganic and organic pigments usually used in paints, for example, titanium dioxide, carbon black, talc, kaolin, calcium carbonate, magnesium carbonate, barium sulfate, iron oxide, cyanine blue, quinacridone red. And so on. As the optional component other than the component (e), a leveling agent, an anti-settling agent, a dispersant, an ultraviolet absorber, a chlorinated polyolefin, a cyclized rubber, a petroleum resin, an antifoaming agent, and an antioxidant can be used.

The paint is produced by using a known pigment disperser such as an attritor or a sand mill to disperse the pigment in a part or all of the resin component, and then adding the remaining resin component, organic solvent and paint additive. Then, it is manufactured by adjusting the viscosity to a predetermined value.

As the coating means for the coating material, any known coating method such as air spraying, air atomizing electrostatic coating, electrostatic atomizing electrostatic coating can be used. Drying is performed at room temperature for 30 minutes to 24 hours or at 60 to 140 ° C. for 5 to 60 minutes to form a coating film.

As the adherend to be coated, steel plate, stainless steel, aluminum, polyamide resin, polybutylene terephthalate resin, ABS resin, polyurethane resin, polyvinyl chloride, polycarbonate resin, unsaturated polyester resin, polypropylene resin, polystyrene, acrylic resin. Resins, phenylene oxide resins and mixed plastics thereof, and reinforced plastic resins thereof,
A metallized plastic in which a plating film of copper, nickel, chromium, zinc or the like or a metal deposition film is formed on the surface of these resins can be used.

[0029]

The coating material obtained by using the coating resin of the present invention can be directly coated on an adherend without a primer, and has weather resistance,
It gives a coating film with a good balance of gasoline resistance, adhesion and flexibility. Further, since it gives a coating film having excellent adhesion to both metal and plastic, it can be applied simultaneously to steel plate materials and plastic materials.

[0030]

The present invention will be described in detail below with reference to examples. (Production of Molded Articles) Example 1 25 parts by weight of hydrogenated styrene / butadiene / styrene block copolymer “Kreton G-1652” (trade name) manufactured by Shell Chemical Co., ethylene (7) with Mooney viscosity of 32
4 parts by weight) and 25 parts by weight of propylene copolymer rubber and 50 parts by weight of propylene-ethylene (7% by weight) block copolymer (MFR 45 g / 10 minutes) manufactured by Mitsubishi Petrochemical Co., Ltd., and manufactured by Kawata Manufacturing Supermarket. Mix for 2 minutes with a mixer and 220 ° C using a PCM twin-screw kneader manufactured by Ikegai Tekko KK
And kneaded and granulated to obtain a composition pellet. Using a screw in-line injection molding machine, the composition of each composition is 2 m at 240 ° C.
A test piece of m, 100 cm × 100 cm was molded.

Example 2 A test piece was molded by injection molding using the above propylene / ethylene block copolymer (EP) alone. Example 3 Polyamide resin material 1013RW-1 (Ube Industries, Ltd.)
(Manufactured, trade name) was molded into a test piece by an injection molding machine at 280 ° C.

Example 4 Polybutylene terephthalate resin (PBT) material 520
A test piece of 1X11 (trade name, manufactured by Toray Industries, Inc.) was molded by an injection molding machine at 250 ° C. Example 5 A test piece of ABS resin material Lustran 240 (trade name, manufactured by Mitsubishi Monsanto Kasei Co., Ltd.) was molded by an injection molding machine at 200 ° C.

Example 6 The ABS resin test piece of Example 5 was subjected to microporochrome electroplating to obtain a test piece. Example 7 A test piece was prepared by cutting an unsaturated polyester resin material (SMC) N12 (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.).

(Production Example of Resin Having Acid Group) Example 1: 1 liter of xylene in a stainless pressure resistant reaction vessel equipped with a thermometer and a stirrer, hydrogenated styrene-butadiene-styrene block copolymer "Kreton" of Shell Chemical Co. G-1652 ″ 100 g was charged, the system was replaced with nitrogen gas, and the temperature was raised to 125 ° C., and then a xylene solution of maleic anhydride and a xylene solution of dicumyl peroxide (maleic anhydride: 1 g / 10 ml) were pumped. , Dicumyl peroxide (0.15 g / 10 ml) from 6 separate conduits.
Then, 4.0 g of maleic anhydride and 0.6 g of dicumyl peroxide were finally fed into the system. After completion of the reaction, the system was cooled to around room temperature, acetone was added, the maleic anhydride graft block copolymer was filtered off, and the precipitate was repeatedly washed with acetone. The washed precipitate was dried under reduced pressure at elevated temperature to obtain a white powdery modified resin. Infrared absorption spectrum measurement and neutralization titration of this modified resin revealed that the content of maleic anhydride group was 1.5.
% By weight.

Example 1 In a flask equipped with a condenser, a thermometer and a stirrer, maleic anhydride-grafted clayton G-1652 obtained as in Example 1 as component (A) (hydrogenated styrene / butadiene / styrene block manufactured by Shell Chemical Co. Polymer) 100 parts,
200 parts of toluene was charged and the temperature was raised to 95 ° C. under a nitrogen gas atmosphere. To this, 80 parts of methyl methacrylate, 20 parts of n-butyl methacrylate and 1 part of methacrylic acid, 1 part of benzoyl peroxide and 50 parts of toluene were added dropwise over 3 hours as the component (B), and 90 to 95 after completion of the addition.
After 12 hours at C, the polymerization was completed to obtain the coating resin B of the present invention.

Example 2 As component (A), the maleic anhydride grafted Kraton G-1652 obtained in Example 1 (maleic anhydride content 1.5 w)
t%) and resin (E) for coating material was obtained in the same manner as in Example 1 except that 40 parts of methyl methacrylate, 20 parts of ethyl acrylate and 30 parts of cyclohexyl methacrylate were used as the component (B).

Comparative Example 1 As the component (A), Kraton G-1652 160
Parts, 20 parts of methyl methacrylate as the component (B), n
A coating resin F was obtained in the same manner as in Example 1 except that 20 parts of butyl methacrylate and 1 part of methacrylic acid were used.

Comparative Example 2 As the component (A), 20 parts of Kraton G-1652,
As component (B), 90 parts of methyl methacrylate, 40 parts of ethyl acrylate, 5 parts of cyclohexyl methacrylate
A coating resin G was obtained in the same manner as in Example 1 except that 0 part and 1 part of methacrylic acid were used.

Comparative Example 3 As the component (A), 20 parts of Kraton G-1652,
As component (B), 90 parts of methyl methacrylate, 40 parts of ethyl acrylate, 5 parts of cyclohexyl methacrylate
A coating resin M was obtained in the same manner as in Example 1 except that 0 part and 10 parts of 2-hydroxyethyl methacrylate were used.

Production Example of Coating Material Resin for coating material (solid content) 35 parts or 25 parts Crosslinkable resin 0 or 5 parts Toluene 40 parts Titanium oxide 25 parts Mixing is carried out so as to disperse in a sand mill for 1 hour and then Table 1 A paint having the composition shown in was obtained.

Details of the components shown in Table 1 are as follows. Blocked isocyanate compound: Coronate 2507
(Nippon Polyurethane Co., Ltd., trade name, solid content 75%) Polyisocyanate compound: Sumidule N-75 (Sumitomo Bayer Urethane Co., Ltd., trade name, solid content 75%,
1,6-hexamethylene diisocyanate trimer) Isobutylated melamine resin: Super Beckamine L-1
16-70 (Nippon Reichhold Co., Ltd., trade name, solid content 70%) Bisphenol A type epoxy compound: Epicoat 834
(Yukaka Shell Epoxy Co., Ltd., trade name, solid content 100
%)

Evaluation of paint Coating on plastics: Production Examples 1 to 4 and 7 of molded articles
The surface of the sheet obtained in 1. was degreased with vapor of 1,1,1-trichloroethane for 1 minute, then the rest was immersed in isopropyl alcohol for 1 minute, air-dried for 1 minute, and then the above-prepared paint was appropriately treated with toluene. After diluting to a viscosity,
It was spray-coated and dried to a film thickness of 40 to 45 μm.
(Application Example and Comparative Application Examples 1 and 2 are baked at 80 ° C. for 30 minutes. Comparative Application Example 3 is baked at 150 ° C. for 30 minutes and dried.) (Painting on steel plate) 0.8 mm × 70 mm × 150 mm cold The rolled steel plate was treated with zinc phosphate by Bonderite # 3004 (trade name of Nippon Parkerizing Co., Ltd.), and the above paint was spray-painted.

Evaluation of coating film Gloss: Measured by specular reflectance of 60 degrees Hardness: Measured by pencil hardness meter Adhesion: 11 lines were drawn by a cutter knife at 1 mm intervals in each direction to reach the material. The cellophane tape was adhered to 100 squares, and when peeled off at once, the coating film was not peeled off, and the number of remaining squares was evaluated. Evaluation criteria are 100/100 (○, excellent), 99 / 100-80
/ 100 (△, acceptable), 79/100 to 50/100
(X, inferior), 49/100 to 0/100 (xx, remarkably inferior). Bending resistance: A 180 ° bent coating film was examined with a 1 / 2φ inch mandrel. ○ (Pass), × (Fail) Gasoline resistance: The test plate was immersed in gasoline for 1 hour, and changes such as discoloration stains, swelling and peeling of the coating film were evaluated. The evaluation criteria are ◎ (no change; excellent), ○ (slightly change; acceptable), △ (swelling that poses a practical problem), × (significant change, peeling; not possible) Moisture resistance: Test plate at temperature 50 Appearance of the coating after 240 hours in a closed box adjusted to ± 1 ° C and relative humidity of 98%,
Check for blisters. Evaluation criteria are good appearance, no blisters: ○ (excellent) Blisters (diameter less than 0.2 mm): △ (possible) Blisters (diameter 0.2 mm or more): × (impossible)

[0044]

[Table 1]

Claims (7)

[Claims] 1. An alkyl having 1 to 8 carbon atoms in an inert solvent in which a hydrogenated product (A) of a styrene-butadiene-styrene block copolymer graft-modified with maleic acid or an acid anhydride thereof is dissolved. A resin composition for coating obtained by polymerizing a vinyl monomer (B) containing 50% by weight or more of an acrylic acid ester or a methacrylic acid ester having a group or a cyclohexyl group. [However, the weight ratio (A / B) of the component (A) and the component (B) is 2/8 to 7/3. ] 2. The vinyl monomer as the component (B) contains a vinyl monomer having a hydroxyl group in a proportion of 0.5 to 20% by weight, according to claim 1. Resin composition for paints. 3. The vinyl monomer as the component (B) is α, β-
The resin composition for coating according to claim 1, which contains an unsaturated carboxylic acid or an acid anhydride thereof in a proportion of 0.1 to 10% by weight. 4. The resin composition for coating composition according to claim 1, wherein the inert organic solvent is toluene or xylene. 5. The resin composition for coating according to claim 2, wherein the vinyl monomer having a hydroxyl group is hydroxyethyl methacrylate. 6. The resin composition for coating according to claim 1, wherein the α, β-unsaturated acid is methacrylic acid. 7. The inert organic solvent comprises the component (A) and the component (B).
50 to 2,000 relative to 100 parts by weight of the resin component of the components
The resin composition for coating according to claim 1, which is used in a proportion of 0 part by weight.