CONTINUOUS PREPARATION OF POLYOLEFIN

PURPOSE:To obtain a polyolefin having improved bulk density and particle size distribution continuously and stably, by polymerizing a substance containing a catalyst system comprising titanium trichloride, etc. and an organoaluminum compound by a continuous polymerizer. CONSTITUTION:A substance containing a catalyst system comprising (A) one solid catalyst component of titanium trichloride (composition) obtained by reducing titanium tetrachloride with an alkyl aluminum compound or a carrier catalyst compound (e.g., silica, etc.) supporting or bonding chemically a titanium compd. to it, a titanium compound, and (B) an organo-aluminum compound (e.g., triethyl aluminum, etc.) is preliminarily polymerized by a continuous polymerizer having a circulation operation by pump until 0.01-1g (based on 1g solid catalyst) olefin (e.g., ethylene, etc.) is polymerized, and then polymerized under heating and pressure, to give a polyolefin having a particle size distribution wherein 10-100 mesh particles are >=95wt%.