Ube Industries, Inc.

Norihisa Komoda

Hiroto Mitsui

Tomohiko Yamamoto

Takuji Takahashi

Kohji Narui

Akira Ishikawa

Kiyotaka Akao

An aromatic polyimide film of polyimide composed of a 3,3&prime;,4,4&prime;-biphenyltetracarboxylic acid component and a p-phenylenediamine component, which has a thickness of 35 to 55 &mgr;m and is employed for manufacturing a polyimide film/metal film laminate, preferably has a linear thermal expansion coefficient of 17&times;10 to 24&times;10 cm/cm/&deg; C. (TD) in the temperature range of 50-200&deg; C., and a modulus of tensile elasticity of 700 kgf/mm or more (TD), and has a surface having been subjected to discharge treatment.

Aromatic polyimide film and film laminate

A tetraester of 3,3&prime;,4,4&prime;-biphenyltetracarboxylic acid is advantageously prepared by a process composed of a step of dimerizing an o-phthalic diester in the presence of a catalyst comprising a powdery palladium salt having a specific surface area of at least 0.5 m,/g and a basic bidentate ligand compound and one or more steps of continuing the dimerization after supplemental addition of at least one of the powdery palladium salt and the basic bidentate ligand compound.

Preparation of tetraester of 3, 3&prime;, 4, 4&prime;, - biphenyltetracarboxylic acid

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Yamaguchi, Japan

Norihisa Komoda