PURPOSE: To obtain the titled copolymer having well balanced physical properties between impact resistance, rigidity, etc., by polymerizing ethylene/propylene batchwise under conditions controlled to give a specific catalytic activity.
CONSTITUTION: Polymerization of ethylene/propylene is carried out continuously at a reaction ratio between ethylene and propylene ≤(6/94)wt% and batchwise at a reaction ratio between ethylene and propylene of (15/85)W(95/5)wt% by the multi-stage polymerizing method in plural connected polymerizers in the presence of a stereoregular catalyst. A catalytic activity reducing agent is added to a slurry in transferring the slurry to the polymerizers to reduce the catalytic activity to (1/4) or less, and the batchwise polymerization is started after transferring the slurry. In the process, an organoaluminum compound is added to improve the activity to 1.1 times that before the addition of the organoaluminum compound and carry out the batchwise polymerization. After the completion of the batchwise polymerization, the slurry is transferred to a zone for deactivating the polymerization activity of the slurry in a time of (1/3) or less the polymerization time in the batchwise polymerizers to afford the aimed copolymer.
FUJIKAGE ICHIROU
UCHIKAWA SHINRIYUU
SHIOMURA TETSUNOSUKE
