Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-12-12
2004-03-09
Shosho, Callie (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S504000, C524S516000, C524S522000, C524S538000, C525S068000
Reexamination Certificate
active
06703437
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a resin composition for electrostatic coating, a resin article formed from the resin composition and a formed resin article produced by coating the resin article electrostatically.
BACKGROUND ART
Rubber-reinforced styrene resin is excellent in impact resistance, moldability and the like, and utilized in various fields including vehicle parts, electrical appliances, business equipment and so on.
Among these fields, the rubber-reinforced styrene resin is chiefly applied to the vehicle parts as being coated for improving design and weatherability.
However, in the case of coating an article formed from the rubber-reinforced styrene resin, there arise problems such as insufficiency in deposition efficiency of a coating composition and difficulty in maintaining uniformity of the quality of coating surface when the article has a complicated shape.
Electrostatic coating has heretofore been performed as a coating method for solving the above problems. However, the electrostatic coating necessitates a step of subjecting an article surface to a conductive primer treatment since the rubber-reinforced styrene resin inherently is an insulating material. A method of mixing a conductive carbon with the resin has also been employed; however, the method has a drawback that impact strength of a coating film is largely decreased.
DISCLOSURE OF INVENTION
The present invention was accomplished to solve the above problems. A main object of the invention is to provide a resin composition for electrostatic coating which comprises a rubber-reinforced aromatic vinyl resin such as a rubber-reinforced styrene resin and is useful for forming an article excellent in various physical properties such as impact resistance; the article formed from the resin composition being suitably used for forming thereon a satisfactory electrostatic coating film without a conductive primer treatment.
Another object of the invention is to provide a resin article formed from the resin composition comprising a rubber-reinforced aromatic vinyl resin, the resin article being excellent in electrostatic coatability and various physical properties.
The inventors carried out an extensive research considering the conventional techniques mentioned above, and found that it is possible to form a satisfactory electrostatic coating film, even without a conductive primer treatment, on a resin article formed from a resin composition comprising a specific rubber-reinforced aromatic vinyl resin, a polyamide elastomer, a modified vinyl polymer containing a specific functional group(s), and an alkali metal salt and that the formed article is excellent in various physical properties such as impact resistance, to thereby accomplish the present invention.
Thus, the present invention provides the following resin composition, resin article formed from the resin composition, and formed resin article produced by coating the article electrostatically.
1. A resin composition for electrostatic coating comprising a rubber-reinforced aromatic vinyl resin (A), a polyamide elastomer (B), a modified vinyl polymer (C) containing at least one functional group selected from the group consisting of carboxyl, epoxy, amino and amido, and an alkali metal salt (D).
2. The resin composition according to item 1, wherein the rubber-reinforced aromatic vinyl resin (A) is a graft copolymer obtainable by polymerizing monomer components (a-2) in the presence of a rubber-like polymer (a-1), or a mixture of said graft copolymer and a copolymer of the monomer components (a-2), the monomer components (a-2) comprising (i) an aromatic vinyl monomer. (ii) at least one monomer selected from the group consisting of a vinyl cyanide monomer and an alkylester monomer of unsaturated carboxylic acid and, when necessary, (iii) another copolymerizable vinyl monomer.
3. The resin composition according to item 1, wherein the polyamide elastomer (B) is obtainable by reacting polyol with at least one compound selected from the group consisting of aminocarboxylic acid having not less than 6 carbon atoms, lactam having not less than 6 carbon atoms and nylon mn salt (m+n≧12).
4. The resin composition according to item 1, wherein the modified vinyl polymer (C) is a copolymer of an ethylenically unsaturated monomer containing at least one functional group selected from the group consisting of carboxyl, epoxy, amino and amido with another ethylenically unsaturated monomer.
5. The resin composition according to item 1, wherein the alkali metal salt (D) is at least one compound selected from the group consisting of potassium thiocyanate and an alkali metal salt of dodecylbenzenesulfonic acid.
6. The resin composition according to any one of items 1-5, comprising 2-96.95 wt. % of the rubber-reinforced aromatic vinyl resin (A), 2-96.95 wt. % of the polyamide elastomer (B), 1-50 wt. % of the modified vinyl polymer (C) and 0.05-10 wt. % of the alkali metal salt (D) when a total amount of the rubber-reinforced aromatic vinyl resin (A), the polyamide elastomer (B), the modified vinyl polymer (C) and the alkali metal salt (D) is 100 wt. %.
7. A formed resin article excellent in electrostatic coatability, which is formed from the resin composition according to any one of items 1-6.
8. A formed resin article having electrostatic coating film, which is produced by electrostatically coating the resin article according to item 7.
The resin composition for electrostatic coating of the present invention comprises a rubber-reinforced aromatic vinyl resin (A), a polyamide elastomer (B), a modified vinyl polymer (C) containing at least one functional group selected from the group consisting of carboxyl, epoxy, amino and amido, and an alkali metal salt (D).
Components comprised in the resin composition of the present invention are described below.
(A) Rubber-reinforced Aromatic Vinyl Resin
The rubber-reinforced aromatic vinyl resin is also known as a rubber-reinforced styrene resin, and is obtainable by polymerizing a rubber-like polymer (a-1) with monomer components (a-2) consisting of (i) an aromatic vinyl monomer, (ii) at least one monomer selected from the group consisting of a vinyl cyanide monomer and an alkylester monomer of unsaturated carboxylic acid and, when necessary, (iii) another copolymerizable vinyl monomer. The rubber-reinforced aromatic vinyl resin may preferably be a graft copolymer obtainable by polymerizing the monomer components (a-2) in the presence of the rubber-like polymer (a-1), or a mixture of the graft copolymer and a copolymer obtainable by polymerizing the monomer components (a-2).
Components constituting the rubber-reinforced aromatic vinyl resin are described below.
(a-1) Rubber-like Polymer
Examples of the rubber-like polymer (a-1) includes polybutadiene, a styrene-butadiene copolymer, a acrylonitrile-butadiene copolymer and like diene polymers, an ethylene-propylene copolymer, an ethylene-propylene-unconjugated diene copolymer and like ethylene-propylene copolymers, acrylic ester copolymers, chlorinated polyethylene and the like. These rubber-like polymers (a-1) are used solely or in combination of two or more.
Preparation process of the rubber-like polymer is not limited, and the rubber-like polymer may be prepared by emulsion polymerization, solution polymerization, suspension polymerization, bulk polymerization or the like according to known conditions. A gel content of the rubber-like polymer is not limited, but may preferably be 0-95%. It is particularly preferred to prepare the rubber-like polymer by the emulsion polymerization from the viewpoint of controllability of the gel content.
(a-2) Monomer Components
The monomer components (a-2) comprise (i) an aromatic vinyl monomer, (ii) at least one monomer selected from the group consisting of a vinyl cyanide monomer and an alkylester monomer of unsaturated carboxylic acid and, when necessary, (iii) another copolymerizable vinyl monomer.
Examples of the aromatic vinyl monomer (i) includes styrene, &agr;-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, t-butyl
Aoki Hiromichi
Kamiyama Shiro
Kohama Katsumi
Sakano Hajime
Takagawa Yasunobu
Nippon A & L Inc.
Shosho Callie
Sughrue & Mion, PLLC
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