POLYESTER FILM AND ITS PRODUCTION

摘要

PURPOSE:To obtain a polyester film provided with uniform surface projections without voids by a method wherein a layer mainly composed of a polyester A is laminated on one surface of a layer mainly composed of a polyester B, and fine projections are formed on the surface by crystallizing the polyester. CONSTITUTION:A film is obtained by laminating a layer A mainly composed of a polyester A on one surface of a layer B mainly composed of a polyester B. On the surface of the layer A, projections caused by its microcrystallization are formed. The layer A is laminated with a thickness not more than 3mum. The polyester A is microcrystallized to form 70% or more of the surface projections of the layer A. The crystallizing parameter A Tcg of the polyester A is up to and including 70 deg.C and lower than the crystallizing parameter DELTATcg of the polyester B.