公开(公告)号：JPS61206624A

公开(公告)日：1986-09-12

申请号：JP4798285

申请日：1985-03-11

Applicant: AGENCY IND SCIENCE TECHN

Inventor： NAKAYAMA KAZUO ,  MIYASHITA KIYOSHI ,  KAIDO AKIRA ,  KANETSUNA HISAAKI

IPC: C08J5/18 ,  B29C55/02 ,  B29K67/00 ,  B29L7/00

Abstract: PURPOSE:To give physical properties fully satisfying with the requirements as the base material of magnetic recording tape such as strength and elastic modulus by a method wherein the film mainly consisting of polyethylene terephthalate is characterized with the specified structural and mechanical factors. CONSTITUTION:The titled film is obtained by forcibly drawing un-orientated amorphous polyester film through a pair of rolls with a narrow gap and, after that, heat-treating the drawn film. The film is characterized with: (a) A crystal face of the film is face-oriented to the surface of the film. (b) An orientation index of the film, which is obtained from the half-width of X-ray diffraction intensity in the direction of the orientation angle of a 010 crystal face, is 92% or more. (c) The images by small-angle X-ray scattering in the edgewise direction of the film show four point images in the shape of laminar lines. (d) The dynamic elastic modulus of the film measured by applying 110Hz vibration is 11 GPs or higher. (e) The shearing strength of the film is 250 MPa or more.