| 摘要 |
A propylene/ethylene block copolymer comprises (by wt): (A) a crystalline propylene block comprising a homopolymer or a copolymer with up to 1 mol. % ethylene or a at least 4C alpha-olefin (60-85%); and (B) a statistical 75/25-35/65 wt. ratio propylene/ethylene copolymer (15-40%), the block copolymer fulfilling certain conditions. A propylene/ethylene block copolymer comprises (by wt): (A) a crystalline propylene block comprising a homopolymer of a copolymer with up to 1 mol. % ethylene or a at least 4C alpha-olefin (60-85%); and (B) a statistical 75/25-35/65 wt. ratio propylene/ethylene copolymer (15-40%), the block copolymer fulfilling at least one of the conditions (1-1) or (1-2) and also fulfilling condition (2). Condition (1-1) is such that (B) consists of 2 types of copolymers, EPA with limiting viscosity (LV) 1.5-4 dl/g and ethylene content (EC) 20-50 wt.% and EPB with LV 0.5-3 dl/g and EC 50-80 wt.%. Condition (1-2) is such that the content of (B) (EPcont), the EC in (B) ((C2/)EP) and the volume of the equivalent diameter (DV) of the dispersed particles corresponding to the (B) formed in the block copolymer conform to relationship (I). Condition (2) is such that the block copolymer has a melt index (MFR) of 5-120 g/10 minutes. Dv at most 1,7 + 0.032 x ((C2')EP) + 0.082 x (EP-cont) (I) |
