Ube Industries, Inc.

Takashi Kohno

Akinori Otani

Hiroshi Inoue

Susumu Morishige

Hideaki Okihara

Toshikazu Hamamoto

Tetsuji Hirano

Toshinori Hosoma

Katsuo Imatani

Kenji Matsubara

Yoshiyuki Miwa

An aromatic polyimide film which is favorably employed for preparing a laminate of an aromatic polyimide film, an adhesive layer, and an electroconductive sheet is made of a polyimide prepared from a tetracarboxylic acid component containing at least 15 molar % of biphenyltetracarboxylic acid (or its dianhydride or ester) and an aromatic diamine component containing at least 5 molar % of phenylenediamine, has a specific edge tearing resistance of 11 to 22 kg/20 mm/10 .mu.m, and contains not more than 0.4 weight percent of a volatile component.

Aromatic polyimide film

An aromatic polyimide film in the form of a continuous tape having a thickness of 50 to 125 .mu.m favorably employed for manufacture of electric circuit is composed of a biphenyltetracarboxylic acid recurring unit and a p-phenylenediamine recurring unit. The polyimide film has the following characteristics: a tensile strength of not lower than 30 kg/mm.sup.2 ; a tensile modules of not lower than 500 kg/mm.sup.2 ; a linear expansion coefficient of not higher than 2.5.times.10.sup.-5 cm/cm/.degree.C.; a heat shrinkage ratio of not higher than 0.05%; a low curling having a maximum curling of not higher than 3 mm for a disk of diameter of 86 mm; and a uniform thickness having a maximum rate of inclination of not more than 3 .mu.m per 10 mm.

Aromatic polyimide film and polyimide/copper foil composite sheet

A process for the preparation of an aromatic polyimide film includes the steps of casting a polyamide acid solution containing an imidization agent on a support in the form of a film, heating the filmy cast solution on the support at a temperature of 80.degree. to 200.degree. C. to obtain a self-supportable film; peeling the self-supportable film from the support; and further heating the film at a temperature of not lower than 300.degree. C. The polyamide acid solution includes a polyamide acid obtained by polymerization reaction of 3,4,3',4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine in a mixture of a polar organic solvent and a small amount of an imidization agent selected from imidazole, a substituted imidazole, benzimidazole, a substituted benzimidazole, isoquinoline, and a substituted pyridine.

Process for the preparation of aromatic polyimide film

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Yamaguchi, Japan

Takashi Kohno