METHOD FOR PRODUCING BIAXIALLY ORIENTED THERMOPLASTIC RESIN FILM

摘要

PROBLEM TO BE SOLVED: To obtain a biaxially oriented thermoplastic resin film which can enlarge the draw ratio of the film to increase the strength of the film because the film is thin and resistant to breakage by solving the problem that the film is not broken in a sequential biaxial orientation method, and the temperature of the end part of the film is not increased to cause the breakage of the film during orientation when the film is biaxially stretched simultaneously. SOLUTION: The molten thermoplastic resin is cooled quickly and solidified into a sheet. After the temperature of the middle part in the width direction of the sheet is made higher than that of the end part in the width direction of the sheet, the sheet is stretched biaxially and simultaneously in the longitudinal direction and in the width direction.