Mitsui Chemicals, Inc.

Kimiyoshi Miura

Atsushi Shibuya

Sadao Yoshimoto

Noboru Koga

Takeshi Suzuki

A process for producing a cycloolefin resin composition comprising a cycloolefin resin and an additive by using a twin-screw extruder is provided, in which loss of the additive caused by volatilization through a vent during kneading is reduced and kneading of resin material with the additive can be sufficiently carried out. When the cycloolefin resin and the additive are kneaded by using a vented twin-screw extruder () to produce the cycloolefin resin composition containing the additive, an additive introduction opening () is disposed downstream of a vent () located nearest to a discharge opening () of the twin-screw extruder, and the additive is charged through the additive introduction opening located at a distance from the discharge opening of the twin-screw extruder in the range between longer than 10D and not longer than 30D.

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Hatsukaichi, Japan

Kimiyoshi Miura