Ube Industries, Inc.

Kazuhiko Yoshioka

Tomohiko Yamamoto

Toshinori Hosoma

Toshiyuki Nishino

Kenji Matsubara

Katsumi Kato

Akinori Ohtani

An aromatic polyimide laminate composed of an aromatic polyimide composite film, a metal film, and a release film is disclosed. The aromatic polyimide composite film is composed of an aromatic polyimide substrate film and two thermoplastic aromatic polyimide layers. Each thermoplastic layer is fixed to each surface of the substrate film. The substrate film has no glass transition temperature of lower than 350&deg; C., and the thermoplastic aromatic polyimide layer has a glass transition temperature of 190-280&deg; C. The metal film is fixed, with no intervening adhesive layer, to one thermoplastic aromatic polyimide layer at a 90&deg; peel strength of 0.8 kg/cm or more and the release film is fixed, with no intervening adhesive layer, to another thermoplastic aromatic polyimide layer at a 90&deg; peel strength of 0.001-0.5 kg/cm, under such condition that the latter peel strength is one half or less of the former peel strength.

Aromatic polyimide laminate

A flexible aromatic polyimide film/metal film composite sheet is composed of a multi-layered polyimide film having a highly heat-resistant aromatic polyimide layer to one surface of which is bonded another aromatic polyimide layer (in which the multi-layer polyimide film is prepared by simultaneous casting), and a metal film which is bonded to the latter polyimide layer by heating under pressure and subsequent cooling under pressure using a double belt press.

Flexible aromatic polymide film/metal film composite sheet

An aromatic polyimide film useful as a face for a magnetic recording material having a back face-side half stratum thereof containing principal filler fine particles which provide a low friction back face-side surface having a centerline average surface roughness of 2 to 10 m .mu.m, and a front face-side half stratum thereof free from the principal filler particles and optionally containing additional filler fine particles having a size of 0.05 to 0.7 time that of the principal filler particles in a concentration of 0.1 to 0.8 time that of the principal filler particles, which additional filler particles provide a high smoothness front face-side surface having a centerline average surface roughness (Ra) of 0.1 to 0.8 time that of the back face-side surface, is produced from a first aromatic polyamic acid solution containing the principal filler particles and a second aromatic polyamic acid solution free from the principal filler particles and optionally containing the additional filler particles, by forming a film-shaped composite solution stream consisting of a first film-shaped solution stream united with a second film shaped solution stream, solidifying the film-shaped composite solution stream, and heat treating the solidified film to convert the polyamic acid to a corresponding polyimide.

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Ube, Japan

Kazuhiko Yoshioka