Side seam-coated welded cans and process for preparation thereof

Claim 1

A process for the preparation of side seam-coated welded cans, which comprises applying a resin paint to a welded can body having a seam formed on the side face thereof at least on one surface of said seam and baking the coated paint to form a coating covering said side seam, wherein said resin paint comprises a dispersion medium composed of a solution of a thermosetting resin and a dispersed phase of resin particles having a number average particle size of 0.1 to 80 μm and being composed of a thermoplastic resin having a softening point of 50° to 300° C. as determined according to the ring and ball method, the volume ratio of the thermosetting resin to the thermoplastic resin in the coating ranges (A) from 95/5 to 25/75 wherein the thermosetting resin forms the continuous phase and the thermoplastic resin forms the dispersed phase or (B) from 20/80 to 1/99 wherein the thermoplastic resin forms the continuous phase and the thermosetting resin forms the dispersed phase, and the paint coated on the side seam is baked under such conditions that evaporation of a solvent in the solution of the dispersion medium is first caused and softening of the thermoplastic resin is then caused, the thermoplastic polymer containing in the main chain or side chain a carboxyl group derived from a carboxylic acid, a carboxylic acid salt, a carboxylic acid anhydride, a carboxylic acid ester, a carboxylic acid amide, a carbonic acid ester, urea, or urethane, the carboxyl groups having a concentration of 12 to 1400 meg per 100 g of the polymer.