Mitsui Petrochemical Industries, Ltd.

Kenji Wakatsuru

Masayuki Okabe

Hidetatsu Murakami

Satoshi Omori

Toshihiro Sagane

Shuji Minami

Shigemi Shiraki

Masahiro Nozaki

Hideaki Yamaguchi

Yoshikatsu Amimoto

Yoshimasa Ogo

Kunihiro Oouchi

Masaru Sudou

Ryosuke Tomita

Tomoko Sueyoshi

Ryuichi Hayashi

Takehiko Kawate

A process for producing an aromatic polyamide which comprises: (a) a dicarboxylic acid component which consists of 30-100 mol % of terephthalic acid and optionally 0-70 mol % of at least one dicarboxylic acid other than terephthalic acid, and (b) a diamine component which consists of 50-100 mol % of an aliphatic alkylenediamine of 4-25 carbons and optionally 0-50 mol % of at least one alicyclic diamine of 3-25 carbons, said process comprising a first step of performing melt reaction of said dicarboxylic acid with said diamine, thereby giving a low molecular weight condensate having an intrinsic viscosity [.eta.] of 0.05-0.6 dl/g, a second step of subjecting it to solid phase polymerization, thereby giving an aromatic polyamide precursor having an intrinsic viscosity [.eta.] of 0.5-1.0 dl/g, and a third step of subjecting it to melt polymerization, thereby giving an aromatic polyamide having a desired intrinsic viscosity [.eta.] of 0.8-2.5 dl/g. This process permits the industrial production of high molecular weight aromatic polyamides in an economical and efficient manner.

Production of aromatic polyamide

Semiaromatic polyamides, processes for preparing the same and

Disclosed is a process for preparing cycloolefin random copolymer pellets, comprising adding an organic polar solvent to a solution of a copolymer obtained by copolymerizing ethylene and a specific cycloolefin and if desired an .alpha.-olefin other than ethylene, in an amount exceeding such an amount that the liquid mixture exhibits the cloud point, separating the copolymer solution utilizing phase separation phenomenon into a concentrated phase containing the cycloolefin random copolymer in a high concentration and a dilute phase containing said copolymer in a low concentration, feeding the obtained concentrated phase to an extruder where the solvents are removed and the copolymer is melted during extrusion processing, followed by pelletizing the copolymer. According to the invention, the steps for preparing cycloolefin random copolymer pellets can be reduced, and moreover, mold staining can De inhibited in the molding process of the resultant pellets because the pellets have low contents of the low molecular weight copolymer, the unreacted monomer, etc.

Process for preparing cycloolefin random copolymer pellets

In accordance with the present invention, there are provided cycloolefin random copolymers composed of ethylene and cycloolefin and containing substantially no polyethylene, and processes for preparing the same. Optical disc substrates prepared from the above-mentioned copolymers are excellent in transparency and also capable of minimizing the occurence of errors in reading of the discs due to quality of the substrates used therefor.

Cycloolefin random copolymer and process for preparing same

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Kuga-gun, Japan

Kenji Wakatsuru