| 摘要 |
PURPOSE:In polymerizing propylene, to obtain a polypropylene having a constant molecular weight efficiently, by using hydrogen concentration and concentration of a specific catalytic component in a polymerization system as controlling values of molecular weight of formed polypropylene. CONSTITUTION:Propylene is polymerized by the use of a catalyst consisting of an active titanium catalyst obtained by supporting titanium chloride on magnesium oxide, an organoaluminum compound and an organic acid ester in the presence of a liquid medium, and propylene is polymerized while controlling molecular weight of formed polypropylene based on hydrogen concentration and concentration of active titanium catalyst in the polymerization system and/or their valiable amounts. To be concrete, the concentration of active titanium catalyst in the polymerization system is detected, and hydrogen concentration is controlled depending upon the relationship between the hydrogen concentration and molecular weight of polypropylene under the detected value, to regulate the molecular weight of polypropylene.
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