JPS56161405A - Production of wide-mw distribution polyolefin - Google Patents

Abstract

PURPOSE: To obtain titled polyolefin by exactly and easily controlling an average MW and a MW distribution, by recovering the desired polymer from a reaction mixture containing a high-MW, medium-MW and low-MW polymers, each prepared in the presence of a common catalyst.

CONSTITUTION: An olefin is polymerized in: (A) a polymerization step wherein a relatively high-MW olefin polymer is produced under reaction conditions including a low modifier concentration and a low reaction temperature and (B) a polymerization step wherein conditions including a high MW-modifier concentration and a high reaction temperature, by using a Ziegler type catalyst improved so as to show a high activity (the reactions in the above steps are carried out in the presence of a catalyst, an inert solvent and an MW-modifier, each common to the both steps). Next, the olefin is polymerized in step (C) wherein a polymer having an MW intermediate between those of the polymers of the preceding steps, in produced under reaction conditions including an MW-modifier concentration and a reaction temperature which are at a level intermediate between those of the preceding steps, in the presence of the reaction mixture obtained by mixing the reaction products of the preceding steps. The resulting reaction mixture is separated to recover the polymer of the purpose.

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