JPS6351477A - Resin composition for coating compound - Google Patents

Abstract

PURPOSE:To obtain the titled composition suitable for coating metals and plastics, having improved weather resistance, by polymerizing a specific acrylic vinyl monomer in an inert solvent having dissolved a hydrogenated styrene butadiene styrene block copolymer. CONSTITUTION:(B) A vinyl monomer (one containing 0.5-20wt.% hydroxyl group-containing vinyl monomer such as preferably hydroxyethyl methacrylate) containing >=50wt.% (meth)acrylic ester containing 1-8C alkyl or cyclohexyl group is polymerized in (A) (ii) an inert solvent consisting of toluene or xylene having dissolved (i) a hydrogenated styrene butadiene styrene block copolymer to give the aimed composition. The ratio of the component i/B is 2/8-7/3 (weight ratio).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention allows one coat of paint to be applied directly to adherends such as plastics and metals without a primer! 7 (1-Coat)
The present invention relates to coating resin compositions useful as potential coating binders.

[Prior art]

In recent years, in the automobile industry, the use of plastic for automobile parts has been rapidly progressing in order to reduce the weight of car bodies, prevent rust, and provide greater freedom in 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, and FR.
Examples include P, polycarbonate resin, mixed plastics thereof, and reinforced plastics.

Generally, many of these plastics are paint-resistant, and in particular, non-polar polyolefin resins are painted through complicated work steps such as pretreatment (oxidation treatment), undercoat, and topcoat.

The same thing can be said about packaging materials, steel frames, steel plates, etc. for buildings other than automobiles, equipment, home appliances, etc., and multiple painting processes are performed on the adherend material, including undercoating and topcoating. .

[Problems with conventional technology]

In particular, we will discuss coatings for paint-resistant polyolefin resin base materials.

Paints based on chlorinated polyolefin resins temporarily adhere to polyethylene and polypropylene, but they have major problems in terms of long-term stability and coating workability. That is, when used for a long period of time, chlorine is released over time, and the coating film tends to yellow or deteriorate in quality, and there are problems with the weather resistance of the coating film, so that it has not been put to practical use as a paint resin.

Pre-treatment (physical treatment such as surface polishing, chromic acid mixture treatment, solvent treatment,
Even after plasma treatment, corona treatment, etc.), it is still difficult to create a coating film with good adhesion.

As a method to improve the above-mentioned problems, especially weather resistance, (1) a paint is proposed in which a general-purpose acrylic resin is blended with a chlorinated polyolefin resin or an unsaturated polycarboxylic acid or its acid anhydride-modified chlorinated polyolefin; (Japanese Unexamined Patent Publication Nos. 57-198764, 60-123565, and 61-860), but the compatibility between the chlorinated polyolefin and the acrylic resin is insufficient, and the effect of improving weather resistance is also insufficient.

(2) Paint resin obtained by polymerizing acrylic monomer in the presence of chlorinated polyolefin resin (Japanese Patent Application Laid-Open No. 56-50971
No. 61-12940) (3) An epoxy compound or epoxy compound having two or more epoxy groups per molecule is added to the product obtained by polymerizing a monomer mixture containing a functional group-containing acrylic monomer in the presence of a chlorinated polyolefin. Paint containing resin (% Kai No. 56-50971) (4) Chlorinated polyolefin modified with unsaturated polycarboxylic acid or its acid anhydride, and epoxy compound having two or more epoxy groups per molecule, or Although various proposals have been made, such as paint C containing an epoxy resin (Japanese Patent Laid-Open No. 60-22383), the improvement effect is insufficient and there are problems with the weather resistance of the coating film.

[Specific measures to solve the problem]

In the present invention, an acrylic ester or a methacrylic ester having an alkyl group or a cyclohexyl group having 1 to 8 carbon atoms is dissolved in a hydrogenated product of a styrene-butadiene-styrene block copolymer in an inert solvent. The object of the present invention is to provide a coating resin composition obtained by intermittent polymerization of a vinyl monomer containing 50% by weight or more.

(However, the weight ratio (A/B) of component (1) and component (03) is from 1 to 7/3. ] Methods for making styrene-butadiene-styrene block copolymers are well known to those skilled in the art, and a typical procedure is disclosed in US Pat. No. 3,265,765 (August 9, 1966).

By hydrogenating the intramolecular double bonds of this block copolymer of styrene and butadiene, a didistomer with improved thermal stability can be obtained. The production of such hydrogenated block copolymers is described, for example, in Japanese Patent Publication No. 42-8704 and Japanese Patent Publication No. 43-66.
No. 36, Special Publication No. 1972-20504, Special Publication No. 1977-35
It is described in each specification such as No. 55. In addition, several compositions using these hydrogenated substances have been proposed, such as JP-A-50-14742 and JP-A-52.
65551, Japanese Patent Publication No. 60-4225, etc., hydrogenated styrene/conjugated diene block copolymer, hydrocarbon oil, rosin ester adhesive, and α-
Compositions in which olefin polymers, waxes, ethylene/vinyl acetate copolymers, etc. are polymerized are disclosed.

Such hydrogen additives are manufactured by 5hell ChemicajL.
(It is sold by the company with the grade name Kraton G-, for example, under the code name ÷1652.

Inert organic solvents for dissolving this hydrogenated styrene-butadiene-styrene block copolymer include aromatic hydrocarbons such as toluene, xylene, and chlorobenzene, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate, butyl acetate, etc. esters, chlorinated solvents such as carbon tetrachloride, tetralin, mineral spirits, and mixed solvents thereof are used.

This inert organic solvent is capable of dissolving the hydrogenated styrene-butadiene-styrene block copolymer and the vinyl monomer of component (), and has a sufficient concentration to dissolve the component (with the captive component). , usually the amount is 50 to 2 of the sum of both.
,000% by weight.

Component (a): The vinyl monomer of component (a) is mainly composed of an acrylic ester or its methacrylic ester equivalent having an alkyl group or cyclohexyl group having 1 to 8 carbon atoms, and if necessary, α.

Contains β-unsaturated carboxylic acid or its acid anhydride, a vinyl monomer having a hydroxyl group, and other vinyl monomers such as styrene, acrylonitrile, divinylbenzene, butanediol diacrylate, and acrylamide in a proportion of 50% by weight or less. You may do so.

Examples of acrylic esters having an alkyl group or cyclohexyl group having 1 to 8 carbon atoms or their methacrylic ester equivalents include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and n-butyl acrylate. , t-butyl acrylate,
Cyclohexyl acrylate and their methacrylic ester equivalents can be used.

These acrylates contribute to improving the weather resistance, adhesion to the substrate, and hardness of the resulting film.

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, and maleic anhydride are used. Moreover, when it is a polybasic acid such as maleic acid or fumaric acid, its half alkyl ester may be used.

These unsaturated acids are used in a proportion of 0.1 to 10% by weight in component (2). Also, the sum of component (a) and (g) is 0.
It is used in a proportion of 0.01 to 5% by weight.

Examples of the vinyl monomer having a hydroxyl group include human dioxyethyl acrylate, hydroxyglobyl acrylate, butanediol monoacrylate, polyethylene glycol monoacrylate, and methacrylate equivalents thereof;
Examples include N-methylol acrylamide, allyl alcohol, hydroxyethyl vinyl ether, human μxyethyl butyl maleate, -monocaprolactone-modified acrylate, and the like.

These hydroxyl group-containing vinyl monomers are included in component ().
5 to 20 weight, 0.1 to the sum of component (G) and component @)
It is used in a proportion of 10% by weight.

These unsaturated acids and vinyl monomers having hydroxyl groups enable the crosslinking reaction of hydrogenated styrene/butadiene/styrene copolymers.

Polymerization: Polymerization is carried out by dropping the vinyl monomer (with a polymerization initiator dissolved) all at once into a solution of hydrogenated styrene/butadiene/styrene block copolymer dissolved in an inert organic solvent. Alternatively, it may be carried out by gradually dropping the mixture and heating it to 65 to 150° C. while stirring. Polymerization time is 1 to 24 hours.

Examples of the polymerization initiator include organic peroxides and azonitrile. Organic peroxides include alkyl peroxides, aryl peroxides, acyl peroxides, aroyl peroxides, ketone peroxides, peroxycarbonates, peroxycarboxylates, and the like. Alkyl peroxides include dilauroyl peroxide, di-tert-butyl peroxide, and tert-butyl hydro-peroxide; aryl peroxides include dicumyl peroxide and cumyl hydroperoxide; acyl peroxides include dilauroyl peroxide; Examples of the aroyl peroxide include dibenzoyl peroxide, and examples of the ketone peroxide include methyl ethyl ketone peroxide and cyclohexanone peroxide. Examples of azonitrile include azobisisobutylnitrile and azobisisopropionitrile.

■The component hydrogenated styrene-butadiene styrene block copolymer is a component that contributes to the adhesion of the coating film to the adherend, bending resistance, and impact resistance. It greatly affects the hardness, solvent resistance, weather resistance, abrasion resistance, etc. of the coating film, and in terms of the balance of all coating film performance, (4
)/) is used in a ratio of 2/ to 7/3 (weight ratio). (If A/@ is less than 74, the adhesion to the substrate will be too poor. Conversely, if it exceeds 74, the solvent resistance and gasoline resistance will be poor.

Resin for paints: Resins obtained by the above polymerization include hydrogenated styrene/butadiene/styrene block copolymers, vinyl monomer copolymers, vinyl monomer grafted hydrogenated styrene/butadiene/styrene block copolymers, etc. is a homogeneously mixed polymer alloy.

The product obtained by polymerization is a solution in which this coating resin is dissolved in an organic solvent, so pigments, dispersants,
A paint may be prepared by blending a leveling agent, a crosslinking agent, etc. Alternatively, after removing the organic solvent, a new organic solvent, pigment, dispersant, etc. may be added to form a paint, or a necessary amount of organic solvent for adjusting the viscosity may be partially removed from the resin solution. Alternatively, it may be added to the resin solution and then blended with pigments etc. to form a paint.

One coat paint: An example of the composition of a paint that can be applied directly to a substrate is shown below.

(,a) 100 parts by weight of resin for paint of the present invention (b
) Crosslinking agent: 0 to 50 parts by weight (c) 100 to s, o o o parts by weight of an organic solvent that dissolves the resin of component (a) and Q) (d) Pigment: 10 to 300 parts by weight (e)
Other optional ingredients: 0 to 10 parts by weight.

However, the crosslinking agent as component (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, and is a resin that has a functional group that reacts with a carboxyl group or a hydroxyl group. polyepoxides having isocyanate groups; polyurethane resins, polyester resins, blocked polyisocquanates having isocyanate groups; acrylic resins, amino resins having reactive functional groups (-OH, -COOH), etc. can be used.

Specific examples of crosslinking agents include (1) Self-reactive compounds, such as amino resins such as melamine resins or urea resins modified with alcohols such as methanol, ethanol, n-butanol, and isobutanol, and polymerizable inorganic resins. Compounds containing saturated groups (e.g. trimethylolpropane triacrylate, polyethylene glycol diacrylate,
Multifunctional acrylates such as pentaerythritol triacrylate; Epoxy acrylates and methacrylates obtained by esterifying the epoxy group of an epoxy compound with acrylic acid or methacrylic acid; Polyurethane acrylates or methacrylates obtained by reacting acrylates or methacrylates having hydroxyl groups with the polyisocyanate compounds described below. methacrylate; melamine acrylate or methacrylate, etc. obtained by reacting the aforementioned melamine resin with an acrylate or methacrylate having a hydroxyl group), and a carboxyl group,
An acrylic product obtained by copolymerizing an acrylic monomer having a functional group such as a hydroxyl group, an anoyl group, or a methyl tal group.

resin, etc.

Also, (2) polyisocyanate compounds (for example, tolylene diisocyanate), 4,4-diphenylmethane diisocyanate, inphorone diisocyanate, l, 6-
Hexamethylene diisocyanate, cyclohexane 1,
Aromatic diisocyanates or aliphatic diisocyanates such as 4-diisocyanate, adducts of these with diols, triols, etc., polyisocyanates such as chain trimers, cyclic trimers, etc. bonded with biuret bonds)
and blocked isocyanate compounds in which all or part of the incyanate groups contained in the above-mentioned polyisocyanate compounds are blocked with a blocking agent such as lower alcohol, monocaprolactam, methyl eteketoxime, diethyl malonate, or phenol. etc.

Furthermore, (3) epoxy compounds include compounds containing one or more, especially two or more, epoxy groups in the molecule, and mixtures thereof, such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A). ), screw (4
- polyglycidyl ethers of polyhydric phenols such as -hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, glycerin, pentaerythritol,
Examples include polyglycidyl ethers of polyhydric alcohols such as trimethylolpropane, diglycidyl ethers of polyalkylene polyethers, and diglycidyl esters of polyhydric carboxylic acids, so-called dimer acids.

In addition, olefins, such as epoxy compounds obtained by oxidizing polybutadiene with peracid, acrylic epoxy compounds obtained by copolymerizing with glycidyl acrylate or glycidyl methacrylate, and phenol novolac-type epoxy compounds obtained by reacting phenol with formalin. compounds, etc., and modified products thereof.

These crosslinking agents may be used alone or in combination of two or more.

Furthermore, these crosslinking agents may be mixed with active hydrogen-containing resins such as acrylic resins, polyester resins, and polyurethane resins having functional groups such as carboxyl groups, hydroxyl groups, amino groups, and imino groups that react chemically.

As the organic solvent for component (c), those exemplified as solvents for dissolving the hydrogenated styrene/butadiene/styrene block copolymer can be used.

Component (d) pigments include inorganic and organic pigments normally used in paints, such as titanium dioxide, carbon black, talc, kaolin, calcium carbonate, magnesium carbonate, barium sulfate, iron oxide, cyanine blue, and quinacridone red. Examples include.

As optional components other than component (e), leveling agents, antisettling agents, dispersants, ultraviolet absorbers, chlorinated polyolefins, cyclized rubbers, petroleum resins, antifoaming agents, and antioxidants can be used.

Paints are manufactured by using a known pigment dispersion machine such as an attritor or sand mill to disperse pigments in part or all of the resin component, then adding the remaining resin component, organic solvent, and paint additives to form a predetermined amount. Manufactured by adjusting the viscosity to .

As the means for applying the paint, any known painting method such as air spray, air atomization electrostatic, electrostatic atomization electrostatic coating, etc. can be used.

Dry at room temperature for 30 minutes to 24 hours, or dry at 60 to 1
Heat at 40°C for 5 to 60 minutes to form a coating film.

The adherends to be painted include steel plates, stainless steel, aluminum, polyamide resin, polybutylene terephthalate resin, ABS resin, polyurethane resin, polyvinyl chloride, polycarbonate resin, unsaturated polyester resin, polypropylene resin, polystyrene, acrylic resin, and phenylene. Oxide resins, mixed plastics thereof, reinforced plastic resins thereof, and metallized plastics in which a plating film or metal vapor deposition film of copper, nickel, chromium, zinc, etc. is formed on the surface of these resins can be used.

〔Effect of the invention〕

A paint obtained using the paint resin of the present invention can be directly applied to an adherend without a brimer, and provides a paint film with a good balance of weather resistance, gasoline resistance, adhesion, and flexibility.

Furthermore, since it provides a coating film with excellent adhesion to both metals and plastics, it can be applied to steel plate materials and plastic materials at the same time.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

(Manufacture of molded products) Example 1 Hydrogenated styrene-butadiene-styrene block copolymer 1 manufactured by Nigel Chemical Co., Ltd. 25 parts by weight of Kraton G-1652'' (trade name), ethylene with a Mooney viscosity of 32 (7
25 parts by weight of propylene copolymer rubber (4% by weight) and 25 parts by weight of propylene copolymer rubber and propylene/ethylene (7% by weight) manufactured by Mitsubishi Yuka.
50 parts by weight of block copolymer (MFR45?/10 minutes) was blended, mixed for 2 minutes using a super mixer manufactured by Shuen Seisakusho, and then mixed using a super mixer manufactured by Shuen Seisakusho. ! The mixture was kneaded and granulated at 220° C. using an iPcM twin-screw kneader to obtain composition pellets. Each composition is put into a screw in-line injection molding machine! 7240℃
A test piece with a wall thickness of 2 mm and a size of 100 cm x 100 cm was molded.

Example 2 The propylene/ethylene block copolymer (EP) described above was used alone and injection molded to form a test piece.

Example 3 Polyamide resin material 1013RW-1 (manufactured by Ube Industries ■,
(trade name) was molded into test pieces using an injection molding machine at 280°C.

Example 4 Polybutylene Tele7 Talate Resin (PBT) Material 52Q
A test piece was molded from IX11 (manufactured by Toshi ■, trade name) using an injection molding machine at 250°C.

Example 5 A test piece was molded from ABS resin material Lu5tran 240 (manufactured by Mitsubishi Monnant Kasei ■, trade name) using an injection molding machine at 200°C.

Example 6 The ABS resin test piece of Example 5 was subjected to microboarochrome electroplating to obtain a test piece.

Example 7 A test piece was prepared by cutting an unsaturated polyester resin material (SMC) Nl 2 (manufactured by Takeda Pharmaceutical Co., Ltd., trade name).

(Production example of resin having acid groups) Example 1: In a stainless steel pressure-resistant reaction vessel equipped with a thermometer and a stirrer, 1 ton of xylene, 1 ton of hydrogenated styrene-butadiene-styrene block copolymer from Shell Chemical Co., Ltd. Kraton Q-16
52" 100f, replace the system with nitrogen gas, and
After raising the temperature to 5°C, a xylene solution of maleic anhydride and a xylene solution of dicumyl peroxide (
Maleic anhydride: 11/10+wjs dicumyl peroxide 0.15 d/10 d) was fed from separate conduits over 6 hours, and finally maleic anhydride 4. Of, 0.62 of dicumyl peroxide was supplied into the system. After the reaction was completed, the system was cooled to around room temperature, acetone was added, the maleic anhydride grafted block copolymer was taken out of the furnace, and the precipitate was washed repeatedly with acetone. The washed precipitate was dried under reduced pressure at an elevated temperature to obtain a modified resin in the form of a white powder. As a result of infrared absorption spectrum measurement and neutralization titration of this modified resin, the content of maleic anhydride groups was found to be 1.5% by weight.
It came out.

(Resin production example) Example 1 Kraton G-1652 (Shell chemical ice-making type styrene-butadiene-styrene block copolymer) as component (■) was placed in a flask equipped with a condenser, a thermometer, and a stirrer.
100 parts of toluene and 200 parts of toluene were charged, and the temperature was raised to 95° C. under a nitrogen gas atmosphere.

To this, 80 parts of methyl methacrylate as component (d),
20 parts n-butyl methacrylate and 1 part methacrylic acid
1 part of benzoyl peroxide and 50 parts of toluene were added dropwise over 3 hours, and after completion of the addition, polymerization was completed at 90 to 95°C for 12 hours to obtain resin A for goldstone of the present invention.

Example 2 Example 1 except that maleic anhydride-grafted Kraton G-1652 (containing maleic anhydride Q 1.5 wt%) obtained in the above example was used instead of Kraton G-1652.
Resin B for paint was obtained in the same manner as above.

Example 3 A coating resin C was obtained in the same manner as in Example 1, except that 50 parts of methyl methacrylate, 30 parts of cyclohexyl methacrylate, 20 parts of ethyl acrylate, and 1 part of methacrylic acid were used as the component (1).

Example 4 ω) 40 parts of methyl methacrylate, 20 parts of ethyl acrylate, 3 parts of cyclohexyl methacrylate
A coating resin was obtained in the same manner as in Example 1, except that 0 parts and 10 parts of 2-hydroxyethyl methacrylate were used.

Example 5 (1) Maleic anhydride grafted Kraton G-1652 obtained in Example 1 (maleic anhydride content 1.5 wt%) was used as a component.
A coating resin E 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 components of.

Comparative Example 1 (4) As a component, 160 parts of Kraton Q-1652,
Coating resin F was obtained in the same manner as in Example 1 using 20 parts of methyl methacrylate, 20 parts of n-butyl methacrylate, and 1 part of methacrylic acid as components (6).

Comparative Example 2 (b) As components, 220 parts of Kraton G-165, [
F]) Components: 90 parts of methyl methacrylate, 40 parts of ethyl acrylate, 5 parts of cyclohexyl methacrylate
Resin G for coating material was obtained in the same manner as in Example 1 except that 0 part of methacrylic acid and 1 part of methacrylic acid were used.

Example 6 80 parts of methyl methacrylate, n-
Resin H for coating material was obtained in the same manner as in Example 1, except that 15 parts of butyl methacrylate and 5 parts of 2-hydroxyethyl acrylate were used.

Example 7 [F]) As a component, 80 parts of methyl methacrylate, n
Resin I for coating material was obtained in the same manner as in Example 1 except that 10 parts of -butyl methacrylate and 10 parts of 2-hydroxypropyl methacrylate were used.

Example 8 Coating resin J was produced in the same manner as in Example 1, except that 50 parts of methyl methacrylate, 30 parts of cyclohexyl methacrylate, 10 parts of ethyl acrylate, 20 parts of styrene and 10 parts of N-methylolmethacrylamide were used as component (B). I got it.

Example 9 (8) As components, 80 parts of methyl methacrylate, 40 parts of ethyl acrylate, 60 parts of cyclohexyl methacrylate, and 20 parts of 2-hydroxyethyl methacrylate.
Resin K for coating material was obtained in the same manner as in Example 1 except that

Example 10 Components: 40 parts of methyl methacrylate, 20 parts of ethyl acrylate, 20 parts of cyclohexyl methacrylate
A paint resin was obtained in the same manner as in Example 1, except that 10 parts of 1-caprolactone-modified methacrylate 1 Plaxel FM-1'' (trade name) manufactured by Daicel Chemical Co., Ltd. was used.

Comparative Example 3 As the Q component, Kraton G-165220 parts, 03)
A coating resin M was obtained in the same manner as in Example 1, except that 90 parts of methyl methacrylate, 40 parts of ethyl acrylate, 50 parts of cyclohexyl methacrylate, and 10 parts of 2-hydroxyethyl methacrylate were used as the components.

(Leaving space below) Paint manufacturing example Resin A-M pieces) 35 parts or 25 parts Crosslinking resin 0 or 5 parts Toluene
40 parts titanium oxide
They were mixed to a total of 25 parts and dispersed in a sand mill for 1 hour to obtain a paint having the composition shown in Table 2.

Details of the components shown in Table 2 are as follows.

Blocked isocyanate compound: Coronate 2507
(manufactured by Nippon Polycrethane ■, product name, solid content 75%) Polyisocyanate compound: Sumidur N-75 (manufactured by Sumitomo Bayer Urethane ■, product name, solid content 75%, 1,
6-hexamethylene diinocyanate trimer) Isobutylated melamine resin varnish - Perbeckamine L-1
16-70 (manufactured by Nippon Reichhold ■, trade name, solid content 70%) Bisphenol A type epoxy compound: Epicote 834
(oiled shell epoxy P3g, product name, solid content ioo%
) Evaluation of paint Coating on plastic: The surface of the sheet obtained in molded product manufacturing examples 1 to 4 and 7 was
．． 1.1-) After degreasing with lychloroethane vapor for 1 minute, immersing the others in isopropyl alcohol for 1 minute, air drying for 1 minute, diluting the above-prepared paint with toluene to an appropriate viscosity, and then forming a film. It was spray coated to a thickness of 40-45μ and dried.

(Application examples 1 to 3.5.7 and comparative application examples 1 and 2 are 80
Bake for 30 minutes at ℃. Application examples 4 and 6 and comparative application example 3 were baked at 150°C for 30 minutes, and application examples 8 and 9 were baked at 140°C for 30 minutes.
Bake for 0 minutes and dry. ) (Coating on steel plate) A cold-rolled steel plate measuring 0.8 mm x 70 mm x 150 m was treated with zinc phosphate using Bonderite Hand 3004 (trade name, manufactured by Nippon Parriki Rising Co., Ltd.), and spray-painted with the above paint.

Evaluation of paint film Gloss = 60 degrees Measured by specular reflectance Hardness: Measured with a pencil hardness meter Adhesion Using a cutter knife, 11 lines were drawn in the vertical and horizontal directions at 1fi intervals, reaching the material, and the resulting 100 lines were Cellophane tape was adhered to the squares and when it was carefully peeled off, the coating film could not be peeled off and evaluation was made based on the number of squares that remained.

Evaluation criteria: 100/100 (Q, excellent), 99/100
~80/100 (Δ, acceptable), 79/100 ~ 50/Zo
o (X, poor), 49/1 o O-0/100 (xx
, significantly inferior).

Flexibility - The condition of the coating film was examined by bending it 180° using a y-inch mandrel. ○ (pass), × (fail) Gasoline resistance: The test plate was immersed in gasoline for 1 hour, and changes in the coating film, such as discoloration and staining, swelling, and peeling, were evaluated. Evaluation criteria are ◎ (no change: excellent), O (slight change;
Acceptable), Δ (swelling that is a practical problem), × (significant change, peeling; not acceptable) Place the moisture resistance test plate in a sealed box adjusted to a temperature of 50 ± 1°C and a relative humidity of 9870 or higher for 240 hours. Examine the appearance of the painted film and whether there is any blistering. Evaluation criteria are good appearance, no bulges, 20 (excellent), bulges (diameter less than 0.2 gourd): Δ (acceptable), bulges (diameter 0.2 wm or more): × (impossible) (margins below)

Claims (1)

[Scope of Claims] 1) Acrylic acid having an alkyl group or cyclohexyl group having 1 to 8 carbon atoms in an inert solvent in which a hydrogenated product (A) of styrene-butadiene and styrene block copolymer is dissolved. ester or methacrylic acid ester
A resin composition for coating material obtained by polymerizing a vinyl monomer (B) containing 0% by weight or more. [However, the weight ratio (A/B) of component (A) and component (B) is 2/8 to 7/3. ] 2) The paint according to claim 1, wherein the vinyl monomer of component (B) contains a vinyl monomer having a hydroxyl group in a proportion of 0.5 to 20% by weight. Resin composition for use. 3) The vinyl monomer of component (B) contains an α,β-unsaturated carboxylic acid or its acid anhydride in a proportion of 0.1 to 10% by weight. The resin composition for paint according to item 1. 4) The resin composition for paint according to claim 1, wherein the inert organic solvent is toluene or xylene. 5) The resin composition for paint according to claim 2, wherein the vinyl monomer having a hydroxyl group is hydroxyethyl methacrylate. 6) The resin composition for paint according to claim 1, wherein the α,β-unsaturated acid is methacrylic acid. 7) Claims characterized in that the inert organic solvent is used in a ratio of 50 to 2,000 parts by weight based on 100 parts by weight of the total resin content of components (A) and (B). 1. The resin composition for paint according to item 1.