Unitika Ltd.

Kazuo Matsukura

Kunio Murakami

Tsugio Nagasawa

Akiyoshi Kozuma

Mituru Uenishi

Tadashi Hayashi

Tomozo Sekiya

A high dielectric-constant film is disclosed. The film may be comprised of one or more layers. At least one layer is comprised of a thermoplastic polymer having dispersed therein a ferroelectric substance having a dielectric-constant of at least 10. The ferroelectric substance is present in an amount of 5% to 80% by weight based on the weight of the entire film. The film provides a high dielectric-constant and can be produced easily and economically.

High dielectric-constant film

A biaxially drawn thermoplastic polyester film is prepared by concurrent-biaxially drawing a thermoplastic polyester film by a tenter method at a drawing temperature higher than the glass transition temperature of the thermoplastic polyester while maintaining the preheating temperature of the film just prior to drawing at a level greater than the drawing temperature and maintaining the subsequent heat-treating temperature immediately after drawing lower than the preheating temperature and carrying out a reheat-treating process in a plurality of steps while elevating the temperature in each step over a substantially equal temperature range.

Process for preparing biaxially drawn thermoplastic polyester film

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Nara, Japan

Kazuo Matsukura