Teijin Limited

Masanori Abe

Katsushi Sasaki

Wataru Funakoshi

Hiroaki Kaneko

Masumi Hirata

Toru Sawaki

Kaoru Iwata

Utami Yonemura

Takeshi Sasaki

Masasi Simonaru

Hidemi Takemoto

Jyuhou Matsuo

Yoshiki Matsuoka

Keisuke Shinohara

Aromatic polycarbonate having a reduced discoloration and improved heat stability, hue, etc. is provided by keeping a pressure in a raw material melting vessel and the linear velocity of a gas in a transporting piping in a specific range, keeping the concentration of a nitrogen-containing basic compound in a specific range, recycling a byproduct containing specific amounts of impurities, suppressing the amounts of a nitrogen-containing basic compound, metallic elements and a silicic acid derivative in the carbonic acid diester at specific values or less, prescribing the material quality of the reaction facilities, and/or forming an oxide layer at the inner wall surfaces of the reaction facilities.

Carbonic acid diester, aromatic polycarbonate and facilities, and preparation thereof

A polycarbonate copolymer which consists essentially of 5 to 95 mol % of recurring units containing a specific spiroglycol unit and 95 to 5 mol % of recurring units containing a specific biphenol unit, and has a reduced viscosity (.eta..sub.sp /c), measured at 20.degree. C. in a solution containing methylene chloride as a solvent and having a concentration of 0.5 g/dl, of at least 0.3 dl/g, a photoelasticity coefficient of 70.times.10.sup.-13 cm.sup.2 /dyne or less, and a glass transition temperature of at least 95.degree. C.; and a process for the production thereof. This polycarbonate copolymer is useful as a material for an information transmission medium or an information recording medium.

Polycarbonate copolymer containing oxaspiroundecane group and production

An acylated cellulose film having a high optical isotropy and uniformity is produced by dissolving an acylated cellulose in a solvent substantially free from water and including, as a principal component, 1,3-dioxolane in a ratio in weight of the acylated cellulose to the solvent of 10/250 to 10/15; spreading the acylated cellulose solution on a film-forming surface of a support; and drying, for example, initially drying the spread solution layer on film-forming surface so as to reduce the content of the residual solvent in the resultant film to 5 to 30% by weight; removing the resultant residual solvent-containing film from the film-forming surface; and finally drying the removed film, while allowing the film to shrink in the transversal direction thereof, at a drying temperature controlled continuously or intermittently to a level satisfying the relationship (I): (Tg'-50.degree. C.).ltoreq.T.ltoreq.(Tg'+20.degree. C.) (I), wherein T is the drying temperature (.degree.C.) and Tg' is a glass transition temperature (.degree.C.) of the solvent-containing film, the temperature Tg' varying in response to the solvent content in the film.

Method of producing an acylated cellulose film

A process for the production of an aromatic polycarbonate, which comprises polycondensing an aromatic dihydroxy compound and a diaryl carbonate in the presence, as a polycondensation catalyst, of at least one alkali metal salt selected from the group consisting of alkali metal salts of ate-complexes of a metal element, which is silicon, germanium, stannum or plumbum, and alkali metal salts of oxoacids of said metal elements. The above aromatic polycarbonate is almost free from being colored, is also almost free from a decrease in polymerization degree when molded, and is further almost free from forming branches and insolubles.

Process for the production of aromatic polycarbonate

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Iwakuni, Japan

Masanori Abe