CONTINUOUS PRODUCTION OF PROPYLENE BLOCK COPOLYMER

摘要

PROBLEM TO BE SOLVED: To provide a process for the continuous production of a propylene block copolymer enabling continuous production of the copolymer stably over a long period without causing the accumulation of particles having small particle diameter. SOLUTION: This production process comprises the 1st stage polymerization step to polymerize anα-olefin composed mainly of liquid propylene in the presence of a stereoregular polymerization catalyst in a single polymerizer 1 in the copresence of hydrogen and the 2nd stage polymerization step to transfer the obtained polymer to a copolymerizer 7 and copolymerize propylene and anα-olefin other than propylene in gaseous phase under the action of the stereoregular polymerization catalyst used in the 1st stage polymerization step and satisfies the following conditions: (1) the polymer slurry obtained by the 1st stage polymerization step is classified into a slurry rich in coarse particles and a slurry rich in fine particles, the former slurry is supplied to the 2nd stage polymerization step and a major part of the latter slurry is returned to the 1st stage polymerization step; (2) a part of the slurry rich in fine particles and obtained by the step (1) is supplied to a low-pressure gas post-treatment system and/or the 2nd stage polymerization step; and (3) the 2nd stage polymerization step is performed in the presence of a deactivating compound.