A method for producing an easily openable cover made of laminated polyester resin metal plates, an easily openable cover and laminated polyester resin metal plate for easily openable cover

摘要

A method of manufacturing an easily openable can lid of a resin laminated metal plate, consisting of the steps of subjecting a resin laminated metal plate for easily openable can lids, which is composed of a metal plate or a surface-treated metal plate one or both surfaces of which are laminated with a crystalline saturated polyester resin film of a thickness of 10-100 νm, elongation of not less than 150 % and crystal melting heat at a crystallinity of not more than 10 % of not less than 10 joule/g to composite extrusion molding using upper and lower metal molds having a radius of round shoulders of 0.1-1.0 mm so as to form a cut guide groove of a thickness of its remaining uncut bottom portion of not more than 1/2 of the thickness of the raw metal plate, and thereafter heat treating the crystalline saturated polyester resin layer around the cut guide groove at a temperature not lower than the cold crystallization starting temperature and lower than the melting point thereof; and easily openable can lid obtained by this method; and a resin laminated metal plate used to obtain the can lid.