Toyo Seikan Kaisha, Ltd.

Toyo Ink Manufacturing Company

Tadashi Kuno

Hisashi Hotta

Shinya Otsuka

Kiyoshi Okugami

Yasuo Yoshimura

Hiroo Suzuki

Disclosed is an aqueous coating resin composition to be applied to a metal substrate, particularly an inner surface of a metal can or can closure on which an undercoating layer is formed. This coating composition comprises an aqueous dispersion of a self-emulsifiable resin composition being obtained by neutralizing a partial reaction product of (A) an acrylic resin with (B) an epoxy resin, with ammonia or an amine selected from the group consisting of alkylamine, alcohol amines and morpholine in an amount sufficient to maintain the pH value of the composition between 5 and 11, said acrylic resin (A) being an alkali neutralizable acrylic resin having a number average molecular weight of from 10,000 to 100,000, which consists of 12 to 30% by weight of acrylic acid or methacrylic acid and 70 to 88% by weight of at least one member selected from the group consisting of styrene, methylstyrene, vinyltoluene and alkyl esters of acrylic acid and methacrylic acid having 1 to 8 carbon atoms in the alkyl group, said epoxy resin (B) being an aromatic epoxy resin having 1.1 to 2.0 epoxy groups on the average in one molecule and a number average molecular weight of at least 1,400, said partial reaction product having excess carboxyl groups in an amount sufficient to maintain the acid value of the self-emulsifiable resin composition between 30 and 200, and excess oxirane group in an amount such that the residual ratio of the oxirane content (R) is within 5 to 95%. This coating composition is excellent in the storage stability owing to the presence of excess carboxyl groups and provides a self-crosslinked coating excellent in the adhesion, processability, flavor retaining property and resistance to boiling water owing to the presence of excess oxirane groups.

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Tokorozawa, Japan

Tadashi Kuno