JPH0657202A - Primer composition - Google Patents

Abstract

PURPOSE:To provide a primer compsn. capable of forming a primer coating film tightly adherent to the surface of a base such as a metal or a molded resin product. CONSTITUTION:A styrene-isoprene block copolymer or a hydrogenation product thereof is graft-copolymerized with at least one modified monomer selected from among monoolefinic dicarboxylic acid and its anhydride and a monoalkyl ester thereof to prepare a modified graft copolymer contg. 0.05-20wt.% modified monomer units. A primer compsn. is prepd. bu compounding the graft copolymer with a polyester resin and an org. solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primer composition having excellent pigment dispersibility, and in particular, it can be used as an undercoat for various metal or resin moldings to improve the adhesion of the paint to the surface of the article to be coated. The present invention relates to a primer composition.

[0002]

2. Description of the Related Art Conventionally, the added value has been increased by coating the surface of a molded product of polyolefin such as polypropylene or by forming another resin layer. However, in general, polyolefin is poor in polarity,
Poor adhesion to general paints and other resins. Therefore, conventionally, the surface of a molded article made of polyolefin has been previously treated with a primer to improve the adhesion and adhesion of the coating material to the surface. Therefore, as a binder resin for a paint that can be applied once to a molded article directly without a primer, a (meth) acrylic acid ester and a hydroxyalkyl ester are added in the presence of a hydrogenated styrene-isoprene block copolymer in an inert solvent. A resin composition for coating obtained by polymerizing (meth) acrylate has been proposed.
(JP-A-63-51477)

[0003]

However, even if the resin composition for coating material described in the above-mentioned JP-A-63-51477 is used, the resulting coating film does not have sufficient peel strength, Good adhesion could not be imparted.
In addition, conventional resin compositions for coatings have poor pigment dispersibility,
When mixed with some pigments, there is a problem that they tend to thicken, aggregate, and settle during storage.

Therefore, an object of the present invention is to coat a polyolefin coating such as polypropylene and other resin molded articles and a metal to form a primer coating film having good adhesion, and further coat a coating film thereon to obtain water resistance. Another object of the present invention is to provide a primer composition capable of obtaining a coating having excellent sharpness. A further object of the present invention is to provide a primer composition having excellent pigment dispersibility and free from the above-mentioned problems.

[0005]

[Means for Solving the Problems] The present invention provides: (1) (A) a styrene / isoprene block copolymer or a hydrogenated product thereof, a monoolefin dicarboxylic acid and an anhydride thereof, and a monoalkyl monoolefin dicarboxylic acid. A modified copolymer obtained by graft-copolymerizing at least one modified monomer selected from an ester so as to contain 0.05 to 20% by weight, (B) a polyester resin, and (C) an organic solvent. 2. The primer composition according to item 1, wherein (A) the styrene / isoprene block copolymer is a copolymer having a styrene content of 10 to 60% by weight. 3. The primer composition according to item 1 or 2, wherein the modified monomer is maleic anhydride. The primer composition according to any one of items 1 to 3, which is modified with a monoepoxy compound 5. The polyester resin has 1 to 50% by weight of the epoxy compound added. 6. The primer composition according to any one of items 1 to 4, which is an epoxy-modified polyester contained by reacting 6. With respect to 70 to 95% by weight of the (A) modified copolymer,
(B) the polyester resin is 5 to 30% by weight,
(C) Organic solvent is 5 to 80 wt% in total of (A) and (B)
The primer composition according to any one of items 1 to 5, which is 95 to 20% by weight with respect to. Regarding

[0006]

When the modified monomer is maleic anhydride,
It is preferable because good effects are exhibited. The polyester resin is preferably modified with a monoepoxy compound. Hereinafter, the primer composition of the present invention will be described in detail.

The modified copolymer which is an essential component of the primer composition of the present invention comprises a styrene-isoprene block copolymer or a hydrogenated product thereof, a monoolefin dicarboxylic acid and its anhydride, and a monoolefin dicarboxylic acid monopolymer. It is obtained by graft-copolymerizing at least one modified monomer selected from alkyl esters.

The styrene-isoprene block copolymer or its hydrogenated product, which is the main constituent of this modified copolymer, contains one or more polymer blocks [S] derived from styrene in the molecule and one A copolymer sharing the polymer block [I] derived from the above isoprene, for example, a copolymer represented by the following formula: [S-IS] _n (where n is 0 or 1). It is a polymer or a hydrogenated product thereof.

Examples of such a styrene / isoprene block copolymer include those obtained by the method described in US Pat. No. 3,265,765, JP-A-61-292743 and the like. Specific examples of this styrene / isoprene block copolymer include those commercially available under the trade names: Califlex TR1107 and TR1117 (both manufactured by Shell Chemical Co., Ltd.).

The hydrogenated products of styrene / isoprene block copolymers are, for example, Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, and Japanese Patent Publication No. 45-20.
Examples thereof include those obtained by the method described in Japanese Patent Publication No. 504, Japanese Patent Publication No. 48-3555, etc. This styrene / isoprene block copolymer or its hydrogenated product is used in tetrahydrofuran solvent in an amount of 40% from the viewpoint of the strength of the coating film of the obtained primer composition and the solid content concentration.
The number average molecular weight measured by gel permeation chromatography at ℃ is 1 × 10 ⁴ to 18 × 1.
0 ⁴ is preferable, and particularly 1.5 × 10 ^{4 to} 12 ×
It is preferably 10 ⁴ .

The styrene content of the styrene / isoprene block copolymer or its hydrogenated product is from 10 to 60% by weight from the viewpoints of adhesion and adhesion strength of the coating film of the primer composition obtained, low temperature characteristics, stickiness and the like. %, Particularly preferably 12 to 55% by weight.

In order to obtain the modified copolymer (A) used in the present invention, the modified monomer graft-copolymerized with the styrene / isoprene block copolymer is a monoolefin dicarboxylic acid and its anhydride, And at least one selected from monoalkyl esters of monoolefin dicarboxylic acids.

As the monoolefin dicarboxylic acid,
Examples thereof include maleic acid, citraconic acid, itaconic acid, glutaconic acid, 3-methyl-2-pentene diacid, 2-methyl-2-pentene diacid, 2-hexene diacid and the like.

Examples of the monoalkyl ester of monoolefin dicarboxylic acid include those obtained by esterifying a part of the carboxyl group of the monoolefin dicarboxylic acid or its anhydride with an alkyl alcohol. The monoalkyl ester of this monoolefin dicarboxylic acid preferably has an esterification rate (complete diesterification rate of 200%) from the viewpoint that a coating film having sufficient storage stability and good water resistance can be obtained. ~ 100%, more preferably 80-100%
What is desirable is. The alkyl group of the monoalkyl esters of the general formula: C n _H are those represented by 2n _{+ 1,} for example, a methyl group, an ethyl group, n- propyl group, n- butyl group, an isopropyl group, and the like.

Among the modified copolymers (A) used in the present invention, the modified copolymer having a monoalkyl ester of monoolefin dicarboxylic acid as a modifying monomer is, for example, a monoalkyl ester of monoolefin dicarboxylic acid. A styrene / isoprene block copolymer; a monoolefin dicarboxylic acid or its anhydride is graft-copolymerized with the styrene / isoprene block copolymer to prepare a graft copolymer, and then the graft copolymer is treated with an alkyl alcohol. It can be produced by a method in which a part of the carboxyl group of the graft copolymer is esterified by reacting with

Grafting amount of at least one modifying monomer selected from the monoolefin dicarboxylic acid and its anhydride in the modified copolymer (A) and the monoalkyl ester of the monoolefin dicarboxylic acid, that is, the modified copolymer ( The content in A) is applied as a primer to a molded article to obtain a coating film with high adhesiveness of the paint.
It is 0.05 to 20% by weight, preferably 0.2 to 18% by weight, from the viewpoint of obtaining a primer composition having good adhesion between the coating film and the molded article and having a good appearance.

The styrene / isoprene block copolymer is added to the monoolefin dicarboxylic acid and its anhydride,
As a method of graft-copolymerizing at least one type of modified monomer selected from monoalkyl esters of monoolefin dicarboxylic acids, various known methods can be mentioned. For example, a method in which a styrene / isoprene block copolymer is dissolved in an organic solvent, the modified monomer and the radical polymerization initiator are added, and the mixture is heated and stirred to carry out a graft copolymerization reaction; A method of heating and melting, adding a modified monomer and a radical polymerization initiator to the resulting melt, and stirring and performing a graft copolymerization reaction; a styrene-isoprene block copolymer, a modified monomer and a radical polymerization initiation A method in which the agents are mixed in advance and the resulting mixture is fed to an extruder to carry out a graft copolymerization reaction while heating and kneading; powdery styrene.
The isoprene block copolymer is impregnated with a solution prepared by dissolving a modified monomer and a radical polymerization initiator in an organic solvent, and then heated to the maximum temperature at which the powdery styrene / isoprene block copolymer is not dissolved. , A method of causing a graft copolymerization reaction, and the like.

At this time, the radical polymerization initiator / modified monomer is usually used in a molar ratio of 1/100 to 3 /.
5, preferably in the range of 1/20 to 1/2. The reaction temperature is preferably 50 ° C. or higher, particularly 80 to 200 ° C., and the reaction time is about 2 to 10 hours. The reaction system may be either a batch system or a continuous system, but the batch system is preferred in order to uniformly carry out the graft copolymerization.

The radical polymerization initiator used in the above graft copolymerization is, for example, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di ( Peroxybenzoate) Hexin-
3,1,4-bis (t-butylbelloxyisopropyl) benzene, lauroyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne 3,2,5-dimethyl-2,5 -Organic peroxides such as di (t-butylperoxy) -hexane; t-butylperacetate, t-butylperbenzoate, t-butylperphenylacetate, t-butylperisobutyrate, t-butylper-sec-octoate, Organic peresters such as t-butyl perpivalate, cumyl perpivalate and t-butyl perdiethyl acetate; azo compounds such as azobisisobutyronitrile and dimethylazoisobutyronitrile. Of these, organic peroxides and organic peresters are preferred, especially dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne-3,2. , 5-dimethyl-2,
5-di (t-butylperoxy) -hexane, 1,4-
Dialkyl peroxides such as bis (t-butylperoxyisopropyl) benzene are preferred.

The primer composition of the present invention further contains a polyester resin in addition to the modified copolymer (A).

The polyester resin (B) is conventionally known and is an esterification reaction product or transesterification reaction product of a polybasic acid and a polyhydric alcohol. Specifically, polybasic acids such as (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, (anhydrous) maleic acid, (anhydrous) pyromellitic acid, (anhydrous) trimellitic acid, (anhydrous) Compounds having 2 to 4 carboxyl groups or carboxylic acid methyl ester groups in one molecule such as succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, dimethyl isophthalate and dimethyl terephthalate, and polyhydric alcohols, For example ethylene glycol,
Propylene glycol, neopentyl glycol, 1,
Esterification reaction or ester with alcohol having 2 to 6 hydroxyl groups in the molecule such as 6-hexanediol, diethylene glycol, triethylene glycol, trimethylolethane, trimethylolpropane, pentaerythritol, glycerin, tricyclodecane dimethanol It can be obtained by an exchange reaction.

The polyester resin (B) can be used without modification, but since it improves the dispersibility of the pigment, it may be an oil or fatty acid such as linseed oil, safflower oil,
Soybean oil, sesame oil, eno oil, hemp oil, grape kernel oil, tung oil, corn oil, sunflower oil, cottonseed oil, walnut oil,
It is preferable to modify with a (semi) drying oil fatty acid such as rubber seed oil, bovine deer oil, fish oil and fatty acids thereof; hydiene fatty acid, tall oil fatty acid, dehydrated castor oil (or fatty acid) and the like. Further, the polyester resin (B) can be greatly improved in dispersibility of the pigment by being modified with a monoepoxy compound in addition to being modified with a fatty acid or the like.

The monoepoxy compound is a compound having one epoxy group (including a glycidyl group) in one molecule, and examples thereof include ethylene oxide, butylene oxide, propylene oxide,

[0024]

[Chemical 1]

(R is a C _{6 to} C ₃₀ linear alkyl group)
Α-olefin oxides such as; glycidyl ethers such as butyl glycidyl ether and phenyl glycidyl ether; Cardura E (trade name, manufactured by Shell Chemical Co., glycidyl ester of versatic acid which is a tertiary fatty acid), glycidyl acrylate, glycidyl Glycidyl ester such as methacrylate: etc., among them, especially Cardura E,

[0026]

[Chemical 2]

(R is a C _{6 to} C ₃₀ linear alkyl group)
Are preferred.

The modification of the polyester resin with the monoepoxy compound is carried out by an addition reaction between a carboxyl group in the polyester resin prepared to have an acid value and an epoxy group in the monoepoxy compound. It is preferable to use a catalyst to promote this addition reaction, and examples of such a catalyst include triethylamine and tri-n.
-Tertiary amines such as butylamine; pyridine, isoquinoline, quinoline, N, N-dimethylaniline, N-
A basic compound such as (β-hydroxyethyl) amine;
Quaternary ammonium salts such as tetraethylammonium bromide, tetramethylammonium iodide; SnCl ₄ ,
Proton acids such as BF ₃ , AlCl ₃ , Lewis acid and HBr; and the like.

The addition of the monoepoxy compound to the polyester resin is carried out by mixing the organic resin solution or dispersion of the polyester resin with the catalyst and the monoepoxy compound, and heating to about 90 to 130 ° C. with stirring. The monoepoxy compound is contained in the addition reaction product in an amount of 1 to 50% by weight, preferably 2 to 30% by weight, more preferably 5 to 20% by weight. If it is less than 1% by weight, the storage stability does not improve, and
If it is more than wt%, the water resistance and the adhesiveness tend to be lowered. The primer composition of the present invention contains an organic solvent (C) in addition to the modified copolymer (A) and the polyester resin (B).

Examples of the organic solvent used include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as hexane, heptane, octane and decane; alicyclic rings such as cyclohexane, cyclohexene and methylcyclohexane. Formula Hydrocarbons; Aliphatic alcohols such as ethanol and isopropanol; Ketone-based solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone; Ester-based solvents such as ethyl acetate; Halogen such as trichloroethylene, lachlorochloroethylene, dichloroethylene and chlorobenzene Chemical hydrocarbons and the like can be mentioned. These are 1
You may use individually by 1 type or in combination of 2 or more types. Among these, aromatic hydrocarbons are preferable, and alkyl group-substituted aromatic hydrocarbons are particularly preferable.

The mixing ratio of the modified copolymer (A) and the polyester resin (B) in the primer composition of the present invention is
(A) 70 to 95% by weight (B) 5 to 30% by weight, preferably (A) 80 to 90% by weight (B)
It is 10 to 20% by weight. The blending ratio of the organic solvent (C) is in the range of 95 to 20% by weight (C) with respect to the total of 5 to 80% by weight of (A) and (B).

The primer composition of the present invention contains the above-mentioned components (A), (B) and (C) as the main components, and further comprises a pigment, a conductive powder, a pigment dispersant, a plasticizer, a surfactant and a sauce. One kind or two or more kinds selected from an inhibitor, a coating surface modifier, a weather resistance improver and the like can be blended.
As the pigment to be used, coloring pigments which are usually blended in paints, anticorrosion pigments, extender pigments, metallic pigments and the like can be used, for example, titanium white as a coloring pigment, carbon black, etc., zinc powder as an anticorrosion pigment, Asbestos as an extender pigment, such as lead zincate, lead chromate, and zinc chromate,
It is preferable to add a pigment such as aluminum powder or mica-like iron oxide as a metallic pigment such as talc or clay.

The conductive powder enables the intermediate coating composition or the top coating composition to be easily coated on the coating film coated with the primer composition of the present invention by an electrostatic coating machine. As the conductive powder, for example, conductive carbon powder such as furnace black and channel black; nickel, aluminum,
Conductive metal powder such as silver and copper; semiconductor powder such as zinc oxide, tin oxide, tungsten oxide and nickel-coated mica;
And so on. The content of the conductive powder is set so that the volume resistivity of the coating film of the present invention is 10 ⁷ Ω · cm or less, particularly 10 ⁵ Ω · cm or less, in order to enable electrostatic coating of the intermediate coating or the top coating. It is preferable that

Since the primer composition of the present invention is excellent in the dispersibility of the above-mentioned pigment and conductive powder and the storage stability after that, the pigment and conductive powder can be mixed and dispersed as they are. In addition, the primer composition can be prepared by previously dispersing the pigment with the polyester resin (B) having excellent pigment dispersibility and then mixing it with other components. The primer composition of the present invention is prepared, for example, by mixing and dispersing the above components using a ball mill, a roll, an attritor, a dissolver or the like.

The primer composition of the present invention is applied directly to members made of metal, plastic, glass, wood, inorganic materials or the like, or is applied to the surface of a film obtained by applying an undercoat paint or an intermediate paint to these members. , Improve adhesion to other coatings. The coating method of the primer composition of the present invention is not particularly limited, and for example, spray coating, electrostatic coating, dip coating, curtain flow coater, flow coating, brush coating and the like can be applied. Coating thickness is usually 3
Is preferably in the range of 50 to 50 μm, and the coating film is dried by leaving it at room temperature or by heating, and the heating temperature is either deformation or deterioration of the article to be coated, the surface to be coated or the primer composition of the present invention. The temperature is not particularly limited as long as it is not higher than the temperature. INDUSTRIAL APPLICABILITY The primer composition of the present invention can be applied not only to the use as a primer for metals, plastics, etc. but also for applications such as adhesives by taking advantage of its excellent adhesiveness, peel strength and water resistance.

[0036]

EXAMPLES Examples and comparative examples of the present invention will be given below.
The present invention will be specifically described, but the present invention is not limited to these examples.

Production Example 1 Production of Modified Copolymer A reactor was charged with 90 g of styrene and 140 g of benzene, the temperature was raised to 40 ° C., 0.003 mol of sec-butyllithium was added, and the temperature was kept at 40 ° C. Then, all styrene was polymerized. Next, 420 g of isoprene was newly added to the reactor, and all isoprene was further polymerized at 40 ° C. Then, 90 g of styrene was newly added, and all styrene was polymerized at 40 ° C. to obtain a styrene / isoprene / styrene block copolymer. When the styrene content and iodine of the obtained styrene / isoprene / styrene block copolymer were measured, each was 30
_Wt%, it was 272gI 2 / 100g. Then, the obtained styrene / isoprene / styrene block copolymer was dissolved in cyclohexane to prepare a solution having a concentration of 10% by weight. To this solution, diatomaceous earth carrying a nickel catalyst in an amount of 0.5 g per 1 g of styrene / isoprene / styrene block copolymer was added, and the mixture was heated to 35 K.
The mixture was reacted under a hydrogen pressure of g / cm ² at 145 to 155 ° C. for 13 hours to obtain a hydrogenated product of a styrene / isoprene / styrene block copolymer. The number average molecular weight and iodine value of the hydrogenated product of the obtained styrene / isoprene / styrene block copolymer were measured and found to be 4.6.
It was x10 < ⁴ >, 3.6 gI < ₂ > / 100g. 250 parts by weight of the hydrogenated product of the styrene / isoprene / styrene block copolymer obtained above and 500 parts by weight of toluene were charged into a pressure reactor having a capacity of 151 equipped with a stirrer and heated with stirring to 145 The temperature was raised to 0 ° C., and the hydrogenated product of the styrene / isoprene / styrene block copolymer was dissolved in toluene. Next, a solution prepared by dissolving 23 g of maleic anhydride in 100 ml of toluene and a solution prepared by dissolving 8 g of di-t-butyl peroxide in 50 ml of toluene were simultaneously added dropwise over 4 hours. After the dropping was completed, the temperature was maintained at 145 ° C. and the reaction was performed for 2 hours. After the completion of the reaction, a large excess of acetone was added to the reaction mixture, the resulting modified copolymer was precipitated, separated by filtration, washed repeatedly with acetone, and dried under reduced pressure to obtain a modified copolymer. The content (graft amount) of maleic anhydride in the obtained modified copolymer was measured and found to be 4.2% by weight.

Production Example 2 Production of Cardura E-Modified Polyester In a reactor, 59 parts by weight of trimethylolpropane, 70 parts by weight of trimethylolethane, 490 parts by weight of phthalic anhydride, Cardura E (glycidyl of Versatic acid manufactured by Shell Chemical Co., Ltd.) 600 parts by weight of ester) and 60 parts by weight of xylene were charged, the reaction was carried out at 190 to 200 ° C. for 90 minutes, the temperature was further raised to 220 ° C. over 45 minutes, and the reaction was carried out at the same temperature for 60 minutes. Then, the reaction product was adjusted to a non-volatile content of 70% by weight with a petroleum solvent to obtain a cardura-modified polyester resin solution having a Gardner viscosity (25 ° C.) of Y to Z ₂ and an acid value of 6.

Example 1 900 parts by weight of a solid content 10% by weight solution of the modified copolymer obtained in Production Example 1 with toluene and 14.3% by weight of a 70% by weight solution of the polyester resin obtained in Production Example 2. White titanium (made by Teika, trade name R-603) 80
Parts by weight and carbon black (trade name H manufactured by Mitsubishi Kasei)
A-100) 2 parts by weight and dispersed by a shaker for 60 minutes to obtain a composition of 996.3 parts by weight of a pigment paste, which is diluted with toluene to obtain a primer composition having a solid content of 18.3% by weight. It was This primer composition was applied to a surface-treated steel plate and an injection-molded product of propylene / ethylene copolymer degreased with trichlene using a spray gun so that the dry film thickness would be 11 μm to form a primer coating film. Formed. Then, an overcoating material (Soflex # 1200 White manufactured by Kansai Paint Co., Ltd.) was applied thereon to give a dry film thickness of 60 μm, and baked at 120 ° C. for 30 minutes. Then, the finished appearance, adhesion test, water resistance, impact resistance, and image clarity were tested. In addition, the pigment settling property of the primer composition was also tested. The test results are shown in Table 1 below.

Example 2 A primer composition was prepared and tested in the same manner as in Example 1 except that a coconut oil modified short oil alkyd resin was used in place of the polyester resin used in Example 1. The results are shown in Table 1.

Comparative Example 1 A primer composition was prepared in the same manner as in Example 1 except that the pigment used in Example 1 was not dispersed and blended in a polyester resin, but the modified copolymer and the shaker were directly mixed and dispersed. And provided for the test. The results are shown in Table 1. The performance test was evaluated according to the following method.

Storage stability: The primer composition was placed in a closed container and stored at 30 ° C. for 10 days, and the condition was examined.
The values in parentheses are the values measured with a grain gauge. ○ No abnormality at all △ Pigment slightly aggregates and sedimentation is observed Finished appearance: Under the brightness of daylight fluorescent lamp of 500 lux or more, the appearance was visually inspected from a position 50 cm away from the surface to be inspected.

Adhesiveness: In accordance with the cross-cut test method described in JISK5400, a cross-cut is made to prepare a test piece, and an adhesive tape (cellophane tape manufactured by Nichiban Co., Ltd.) is used on the cross-cut of the test piece. After sticking it on the surface, it is quickly pulled in the direction of 90 ° to peel it off,
The number of grids that were not peeled off out of 0 was counted and used as an index of adhesiveness.

Impact resistance: JIS K 5400-197
According to the 96.13.3B method, in a -20 degreeC atmosphere, the weight of 50 g was dropped from the height of 50 cm, and the damage of the coating film was investigated. ○ No abnormality △ Slight cracks or peeling occurred

Image clarity: Evaluated using a sharpness gloss meter (Tokyo Koden Co., Ltd., pgd-4 type).

[0046]

EFFECTS OF THE INVENTION The primer composition of the present invention is excellent in adhesion to metals and resin molded products, so that it may be undercoated on the surface of these substrates to form a primer coating film having sufficient adhesion. I can. Furthermore, the primer composition of the present invention has excellent pigment dispersion stability and does not cause aggregation or sedimentation of the pigment during storage.Therefore, a coating film obtained by applying this to a substrate and a coating material further applied thereto. The finish appearance of the resulting coating film is significantly improved.

[Table 1]

[Procedure amendment]

[Submission date] August 20, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

A styrene-isoprene block copolymer or a hydrogenated product thereof, which is a main constituent component of this modified copolymer, contains a polymer block [S] derived from one or more styrenes in the molecule and one It is a copolymer that shares the polymer block [I] derived from the above isoprene and has, for example, the following formula: (In the formula, n is 0 or 1) or a hydrogenated product thereof.

Claims (6)

[Claims] 1. A modified styrene / isoprene block copolymer (A) or a hydrogenated product thereof, comprising at least one modified monomer selected from monoolefin dicarboxylic acid and its anhydride, and monoalkyl ester of monoolefin dicarboxylic acid. A primer composition comprising a modified copolymer obtained by graft copolymerization so as to contain 0.05 to 20% by weight of a polymer, (B) a polyester resin, and (C) an organic solvent. 2. The primer composition according to claim 1, wherein the styrene / isoprene block copolymer (A) is a copolymer having a styrene content of 10 to 60% by weight. 3. The primer composition according to claim 1, wherein the modified monomer is maleic anhydride. 4. The polyester resin is a resin modified with a monoepoxy compound.
The primer composition according to any one of items 1 to 3. 5. The primer composition according to any one of claims 1 to 4, wherein the polyester resin is an epoxy-modified polyester containing 1 to 50% by weight of an epoxy compound by addition reaction. 6. The (A) modified copolymer is 70 to 95% by weight, and the (B) polyester resin is 5 to 30% by weight, and the (C) organic solvent is the sum of (A) and (B). The primer composition according to any one of claims 1 to 5, which is 95 to 20% by weight with respect to 5 to 80% by weight.