| 摘要 |
PURPOSE:To provide the subject polypropylene satisfied with specific quality conditions and having excellent transparency, impact-resistant strength, etc., by polymerizing propylene in the presence of a highly stereoregular catalyst and subsequently degrading the polymer into low mol.wt. propylene polymer. CONSTITUTION:Propylene homopolymer produced by polymerizing propylene in the presence of a highly stereoregular catalyst (preferably a combination of an organic aluminum compound component with a solid catalyst component containing an electron donor such as magnesium or titanium as an essential component) is melt-kneaded in the presence of a free radical generator (e.g. t-butyl hydroxide) to degrade the propylene homopolymer into the objective polypropylene having a melt-flow rate(MFR) of 1-10g/10min (based on ASTM- D-1238), a weight-average mol.wt. (MW)/number-average mol.wt. (MN) of 2.5-4.0, a density of >=0.9070g/cm<3> based on JIS K7112 D) and a xylene-soluble content(CXS) of <=2.5wt.% at the ordinary temperature. |
