Mitsui Toatsu Chemicals, Incorporated

Masumi Saruwatari

Yasuhiro Fujii

Shinobu Moriya

Shoichi Tsuji

Yasuhiko Ohta

Masahiro Ohta

Yasuko Honji

Toshiyuki Nakakura

Syoichi Tsuji

Masami Nakano

Akihiro Yamaguchi

Shoji Tamai

Shuji Matsumura

Kazunari Okada

Formed polyimide article

A polyimide film essentially consisting of polyimide having recurring units of the formula (I): ##STR1## which has a density of 1.335 to 1.390 g/cm.sup.3 at 23.degree. C. and/or a refractive index of 1.605 to 1.680 at 23.degree. C. in the direction of thickness and is transparent; and a preparation process of the polyimide film by extruding the polyimide having recurring units of the above formula (I) through a common melt-extrusion process, casting in a chill-roller to obtain an unstretched film, uniaxially or biaxially stretching the unstretched film to cause molecular orientation, and successively setting the stretched film through heat-treatment.

Polyimide film and preparation process of the film

Method for preparing biaxially stretched polyether ether ketone film

Polyimide sheets having excellent thermal resistance and good surface appearance of the resultant sheets are obtained by a melt-extrusion process from a specific polyimide in the temperature range of 300.degree. C. to 450.degree. C. and a moisture content of 200 ppm or less.

Polyimide sheet and preparation process of the sheet

An insulated wire having excellent thermal resistance and good surface appearance is obtained by coating a condutor with a specific polyimide in a temperature range of 300.degree. C. to 450.degree. C. and controlling moisture content to 200 ppm or less.

Process for preparing insulated wire

Polyimide which is obtained by polymerization and consists essentially of recurring structural units of the formula (I): ##STR1## wherein X is a single bond or a hexafluoroisopropylidene group, is processed to a form of pellet, followed by heat-treating to obtain crystallinity of 5% or more, and fed to an extruder to obtain articles.

Extrusion process of polyimide and polyimide pellet used for the process

A process for the preparation of a polyimide molded form comprising the steps of swelling a primary-molded form consisting essentially of polyimide having recurring units of the formula (I) ##STR1## by using an aprotic polar solvent and subsequently stretching the swelled form.

Process for preparing a polyimide molded form

In the preparation of a film by melt-extrusion process of thermoplastic polyimide, static charge is applied to a molten film, primary cooling is carried out by adhering the film to a cooling roller having a surface temperature in the range of from the glass transition temperature of said polyimide -50.degree. C. to the glass transition temperature -15.degree. C., the film is successively cooled to 60.degree. C. and less without bringing the film into contact with rollers, and is taken up under tension to give a polyimide film.

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Nagoya, Japan

Masumi Saruwatari