HIGH MELT-VISCOELASTIC POLYPROPYLENE FOR POST- PROCESSED SHEETS AND FOR BLOW MOLDING

摘要

A polypropylene (PP) having a superior postprocessability and blow moldability is provided, which PP is obtained by polymerizing propylene at multiple stages using a catalyst comprising a TiC?3 composition, an organoaluminum compound and a molecular weight (M.W.) modifier, the resulting final polymer comprising a higher M.W. portion and a lower M.W. portion having a melt flow index of 0.03 to 2.0 g/10 min., and between this index and a melt flow index (10.2 kg/10 minutes, 230.degree.C) as measured under 5 times the load applied in the measurement of the former melt flow index, there being a relationship log HMI ? 0.922 log MI + 1.44, and the final polymer consisting of 40 to 60 weight % of a PP portion corresponding to the higher M.W. portion and 60 to 40 weight % of a PP portion corresponding to the lower M.W. portion.