PURPOSE: To reduce an oligomer deposit amount in a rolled state while forming ideal surface projections by a method wherein a thermoplastic resin film containing inactive particles has a specific average particle diameter and a specific relative standard deviation in a height distribution of film surface projections.
CONSTITUTION: A film made of a thermoplastic resin A containing inactive particles has an average particle diameter of 0.1-10 times a film thickness and a relative standard deviation of 0.6 or more in a height distribution of film surface projections caused by the particles. A biaxially oriented thermoplastic resin film is preferably made of a laminated film of esp. two or more layers. Namely, the film of the thermoplastic resin A is laminated on at least one surface of a film of a thermoplastic resin B. The kind of the inactive particles is inorganic particles of calcium carbonate, alumina, zirconia, or the like or organic particles of crosslinked polystyrene, divinylbenzene, or the like. In this manner, the contact part of film surface projections is reduced, and an oligomer deposite amount is reduced.
ABE KOICHI
OKAZAKI IWAO
