Patent ID: 6045858
Filing Date: 2000-04-04
Classification: B26D,B26F,B29C,B29K,C09J

Abstract:
A process for producing a film comprising:(a) preparing a perforate layer of a thermoplastic resin by pressing a roller having a plurality of protrusions against a roller having a substrate thereon, said substrate having a front surface and a back surface, said substrate comprising a layer of thermoplastic resin to obtain a substrate having a plurality of perforations and burrs on said back surface; and(b) subjecting the substrate having a plurality of perforations to a heat treatment while conducting said pressing whereby burrs that may have formed on the substrate become flush with the back surface which is apart from the perforation, and whereby after the heat treatment the diameter of the perforation on the back surface of the substrate is substantially zero or in a range of from about 1/10 to about 1/4 of the diameter in the front surface.