PURPOSE: To obtain at a high catalytic efficiency the title copolymer which has a rubbery copolymer segment having a high mol.wt. by conducting polymerization under specific conditions in the presence of a given catalyst.
CONSTITUTION: A catalyst comprising a TiCl3-containing solid (a) (e.g. SB-12 manufacture by Tosoh Akzo Corp.) and an alkylaluminum compound represented by the formula AlR3-nXn wherein R is a 1-8C alkyl, X is halogen, and 0<n<3 is used to obtain the title copolymer whose part soluble in xylene at 20°C has a weight-average mol.wt. of 400,000 or higher. This process comprises the first step in which propylene or a mixture thereof with a small amount of other α-olefin (e.g. ethylene) is polymerized, followed by the second step in which a trialkylaluminum (d) (e.g. triethylaluminum) is added to the resulting catalyst system still retaining activity to polymerize propylene or a mixture thereof with other α-olefin. The drawing shows the process.
IMAOKA KOJI
SUZUKI KAZUTAKA
YAMADA SHINICHIRO
