Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-12-26
2002-09-17
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S400000, C523S402000, C523S406000
Reexamination Certificate
active
06451877
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a resin composition used in an electrodeposition coating composition and capable of forming an electrodeposition coating film showing good properties in corrosion resistance, finish appearance and weather resistance.
(2) Description of Background Art
A cationic electrodeposition coating composition consisting of a combination of an epoxy resin with a blocked polyisocyanate as a resin component has a strong anti-corrosive power and has widely been used in the art. However, in the field of an industrial coating such as in electrical appliances, one coat electrodeposition coating finish is demanded to obtain a coating film showing good properties in coating film finish appearance and weather resistance in addition to corrosion resistance.
For example, Japanese Patent Publication No. 44906/86, Japanese Patent Application Laid-Open No. 60045/96, etc. disclose an acrylic resin composition used in a cationic electrodeposition coating composition and capable of forming a coating film showing good properties in corrosion resistance and weather resistance. Japanese Patent Publication No. 44906/86 discloses an acrylic resin composition used in a cationic electrodeposition coating composition and consisting of a reaction product of an epoxy group-containing vinyl copolymer obtained by the normal solution radical polymerization with a secondary amine, and a reaction product of an epoxy resin esterified with an unsaturated fatty acid or added with a secondary amine with a partly blocked polyisocyanate. Japanese Patent Application Laid-Open No. 60045/96 discloses a resin composition used in a cationic electrodeposition coating composition and containing an acrylic resin prepared by amine-modifying a glycidyl group of a glycidyl group-containing copolymer obtained by the normal solution radical polymerization, and a blocked polyisocyanate.
However, these acrylic resin compositions have such a problem as to result an unsatisfactory finish appearance.
For the purpose of improving a finish appearance of a coating film, use of an acrylic resin prepared by the use of a mercaptan-based chain transfer agent, having a relatively small molecular weight and showing good flowability on heat curing an electrodeposition coating film is proposed, resulting in producing such a problem that the mercaptan remaining in the resulting coating film may reduce the corrosion resistance of the coating film.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a resin composition used in the electrodeposition coating composition and capable of forming a coating film showing good properties in corrosion resistance, finish appearance and weather resistance.
That is, the present invention provides a resin composition used in an electrodeposition coating composition and containing an amine-modified vinyl resin (A) prepared by addition reaction of a secondary amine to an epoxy group-containing vinyl copolymer obtained by copolymerizing 2 to 30 parts by weight of an epoxy group-containing polymerizable unsaturated monomer (a-1) and 70 to 98 parts by weight of other polymerizable unsaturated monomer (a-2) copolymerizable with the monomer (a-1) by a catalytic chain transfer polymerization and having a weight average molecular weight of 2,000 to 20,000, and a blocked polyisocyanate (B).
The present invention also provides a resin composition used in an electrodeposition coating composition and further containing an amine-modified epoxy resin (C).
DETAILED DESCRIPTION OF THE INVENTION
The resin composition used in the electrodeposition coating composition in the present invention contains the following amine-modified vinyl resin (A) and a blocked polyisocyanate (B).
The amine-modified vinyl resin (A) is a resin prepared by an addition reaction of a secondary amine to an epoxy group-containing vinyl copolymer obtained by copolymerizing an epoxy group-containing polymerizable unsaturated monomer (a-1) and other polymerizable unsaturated monomer (a-2) copolymerizable with the monomer (a-1) by a catalytic chain transfer polymerization.
Epoxy Group-Containing Polymerizable Unsaturated Monomer (a-1)
The epoxy group-containing polymerizable unsaturated monomer (a-1) is a monomer used for the purpose of introducing epoxy group into a copolymer, and may include, as typical examples, glycidyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, &bgr;-methylglycidyl (meth)acrylate, allylglycidyl ether, and the like. In the present invention, “(meth)acrylate “means “acrylate or methacrylate”.
Other Polymerizable Unsaturated Monomer (a-2)
Other polymerizable unsaturated monomer (a-2) is a monomer copolymerizable with the epoxy group-containing polymerizable unsaturated monomer (a-1) and other than the epoxy group-containing polymerizable unsaturated monomer (a-1).
Typical examples of other polymerizable unsaturated monomer (a-2) may include C
1-24
alkyl (meth)acrylate having a alkyl straight chain, a branched alkyl chain or a cyclic alkyl group, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl meth(acrylate), cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate and the like; carboxyl group-containing polymerizable unsaturated monomer or polymerizable unsaturated group-containing acid anhydride such as (meth)acrylic acid, maleic acid, maleic anhydride and the like; hydroxyl group-containing polymerizable unsaturated monomer such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like; (meth)acrylamide or derivatives thereof, for example, N,N-dimethylaminoethyl (meth)acrylamide, N, N-diethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N-methylol acrylamide methyl ether, N-methylol acrylamide butyl ether and the like; oxetane ring-containing ethylenicaly unsaturated monomer such as 3-ethyl-3-methacryloyloxymethyl oxetane, 3-methyl- 3-methacryloyloxymethyl oxetane, 3-butyl-3-methacryloyloxymethyl oxetane and the like; (meth)acrylonitrile, styrene, vinyl acetate, piperidinyl-containing (meth)acrylate, for example, FA-711MM and FA-712HM (trade names, marketed by Hitachi Chemical Co., Ltd. respectively), fluorine-containing alkyl (meth)acrylate, siloxane chain-containing (meth)acrylate, isocyanato group-containing monomer, alkoxysilyl group-containing (meth)acrylate, and the like. These polymerizable unsaturated monomers may be used alone or in combination.
In the present invention, the epoxy group-containing vinyl copolymer may be obtained by copolymerizing an epoxy group-containing polymerizable unsaturated monomer (a-1) and other polymerizable unsaturated monomer (a-2) according to the catalytic chain transfer polymerization (CCTP).
The catalytic chain transfer polymerization is a polymerization such as a solution polymerization in an organic solvent, an emulsion polymerization in water, or the like of a polymerizable unsaturated monomer in the presence of a metal complex as a catalytic chain transfer agent and a radical polymerization initiator as disclosed, for example, in Japanese Patent Publication Nos. 23209/94 and 35411/95, Japanese Patent Published No. 501457/97, Japanese Patent Application Laid-Open No. 176256/97, Macromolecules 1996, 29, 8083-8089, etc.
The metal complex may include, for example, cobalt complex, iron complex, nickel complex, ruthenium complex, rhodium complex, palladium complex, rhenium complex, iridium complex and the like. Of these, the cobalt complex effectively acts as the chain transfer agent to be preferable.
The cobalt complex may include ones disclosed in, for example, Japanese Patent Publication Nos. 23209/94 and 35411/95, U.S. Pat. Nos. 4526945, 4694054, 4837326, 4886861 and 5324879, W
Sawada Hidenori
Shimasaki Akihiko
Cain Edward J.
Fisher Christen & Sabol
Kansai Paint Co. Ltd.
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