PROCESS FOR OLEFIN POLYMERIZATION

摘要

The present invention aims to provide a process for polymerizing at least one olefin in the presence of a polymerization catalyst comprising the steps of: (A) continuously introducing a first liquid comprising a transition metal compound, an organometallic compound of a metal of Group 13 of Periodic System of Elements and a solvent, and a second liquid which together with said first liquid is capable of forming an emulsion, into an emulsification stage to produce an emulsion comprising said first liquid dispersed in said second liquid; (B) continuously withdrawing an emulsion stream from said emulsification stage and directing it into a solidification stage to form a slurry comprising a solid polymerization catalyst component comprising said transition metal compound and said organometallic compound suspended in said second liquid; (C) continuously recovering said solid polymerization catalyst component from said solidification stage; (D) directing said solid polymerization catalyst component into a first prepolymerization stage together with a monomer and an amount of second liquid wherein the monomer is prepolymerized onto said solid polymerization catalyst component so that the ratio of the weight of the polymer to the weight of said solid polymerization catalyst component is from 0.1:1 to 20:1 to form a slurry of a prepolymerized solid polymerization catalyst component suspended in said second liquid; (E) recovering said prepolymerized solid polymerization catalyst component from said first prepolymerization stage; (F) continuously introducing said prepolymerized solid polymerization catalyst component into a second prepolymerization stage together with an olefin monomer to form a prepolymerized catalyst comprising in average 100 to 1000 g of polymer per 1 gram of said solid polymerization catalyst component; (G) continuously withdrawing said prepolymerized catalyst from said second prepolymerization stage and directing it into a subsequent polymerization stage together with at least one olefin monomer to effect polymerization of the at least one olefin monomer in the presence of said prepolymerized catalyst. The polymerization process produces polymers in high yield. The morphology of the polymer powder is good and the amount of fine particle polymer is low. The process can be operated for long a long period in a stable manner.