Mitsubishi Chemical Industries Limited

Kunio Bizen

Seiji Sakamoto

Masamichi Watanabe

Yuzo Otani

Takuo Nakahara

Akikazu Yano

Masahiro Morita

Yukio Watanabe

Masaaki Sugimoto

Tsunemitsu Hasegawa

A process for producing a porous film or sheet, which comprises melt-molding a composition prepared by compounding 100 parts by weight of a polyolefin resin with 25 to 400 parts by weight of a filler and 1 to 100 parts by weight of a liquid or waxy hydrocarbon polymer into film or sheet, and stretching the resulting film or sheet.

Process for producing porous film or sheet

A polyester film is disclosed which comprises a polyester mainly consisting of polyethylene terephthalate and an additive amount of granular calcium terephthalate anhydride particles having a specific volume shape factor. The average particle diameter and additive amount of the granular calcium terephthalate anhydride particles may be controlled so that the film is particularly suitable as a metallized film or a condenser film.

Polyester films

A polyester film is disclosed which comprises (a) a polyester mainly consisting of polyethylene terephthalate which includes first inert particles being precipitated in the polyester-forming reaction system and having an average particle diameter of 1 to 3 microns and which shows a solution haze of 25 to 75% and (b) an additive amount of second inert substance particles which are added to said polyester (a) insoluble in said polyester (a), inert to the polyester-forming reaction and have an average particle diameter of 1 to 5 microns. The film is useful as a base of a magnetic tape.

Polyester films useful as magnetic tapes

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Yokohama, Japan

Kunio Bizen