Ube Industries, Inc.

Kenji Kuniyasu

Toshiyuki Nishino

Haruhiko Miyazaki

Kenji Nishimura

Yuji Matsui

Kazuhiko Mitsui

Satoru Ono

Kiyoshi Kumagawa

Disclosed is an aromatic polyimide film which is well resistant to sagging and dimensional change in the heat treatment. The aromatic polyimide film is formed from a polymer solution which is produced by a polymerization reaction of a biphenyltetracarboxylic acid component and a phenylenediamine component, and characterized in that any rectangle optionally supposed within the film has a ratio between a length of any side and a length of the central portion between the side and a side opposite thereto is in the range of 100:100 to 100:100.15, and a heat shrinkage ratio of the film is not more than 0.3% (0.003) in any direction after the film is heated at 300.degree. C. for 2 hours. A process for the preparation of the above aromatic polyimide film is also disclosed.

Aromatic polyimide film and process for the preparation of the same

A dimensionally stable polyimide film and processes for the preparation thereof. The polyimide film is composed of an aromatic polyimide obtained from a solution of a polymer formed by polymerization of a biphenyl-tetracarboxylic acid and a phenylene diamine, wherein the average linear expansion coefficient of the polyimide film in the temperature range of from 50.degree. C. to 300.degree. C. is 0.1.times.10.sup.-5 to 2.5.times.10.sup.-5 cm/cm..degree.C., the ratio of the linear expansion coefficient in the machine direction of the film to the linear expansion coefficient in the transverse direction of the film is in the range of from 1/5 to 4, and the thermal dimension stability expressed by the ratio of the change of the size of the film at normal temperature after the heat treatment where the temperature is elevated to 400.degree. C. from normal temperature and the film is maintained at 400.degree. C. for 2 hours is less than 0.3%.

Dimensionally stable polyimide film and process for preparation thereof

Disclosed is a process for separating 11-cyanoundecanoic acid, cyclohexanone and .epsilon.-caprolactam from a pyrolysis product obtained by pyrolyzing 1,1'-peroxydicyclohexylamine in the presence of steam at a temperature of 300.degree. to 1,000.degree. C. The pyrolysis product is first contacted with a mixture comprised of aqueous ammonia and at least one organic solvent selected from benzene, toluene and xylene, and the so prepared liquid is separated into the oily layer and the aqueous layer. On one hand, the oily layer is distilled to separate cyclohexanone therefrom. On the other hand, the aqueous layer is acidified to a pH of below 4.0 by adding thereto a mineral acid and maintained at a temperature of 40.degree. to 100.degree. C. to separate crude 11-cyanoundecanoic acid in molten form from the aqueous layer, and then, the separated crude molten 11-cyanoundecanoic acid is washed with hot water to extract .epsilon.-caprolactam therefrom.

Process for separating 11-cyanoundecanoic acid, cyclohexanone and .epsilon.

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Ube, Japan

Kenji Kuniyasu