Disclosed is a polypropylene composition excellent in balance of low temperature impact-strength, rigidity, heat-resisting property and transparency, which is featured by comprising 20-95% by weight of a polypropylene defined in the following [I] and 5-80% by weight of a propylene-α-olefin copolymer defined in the following [II]:
[I] a polypropylene featured by having:
(1) a ratio of isotactic pentad (mmmm) is 0.900 - 0.949,
(2) the 2,1- and 1,3-propylene units in the polymer chain is 0-1 mole %,
(3) a weight average molecular weight (Mw) is 40,000-1,000,000,
(4) a ratio of a weight average molecular weight (Mw) to a number average molecular weight (Mn), i.e. (Mw)/(Mn) is 1.5-3.8, and
(5) in case of elevating the temperature of o-dichlorobenzene continuously or stepwise up to given temperatures to measure the amount of eluted polypropylene at each temperature, the position of a main elution peak is 95-110°C and the amount of components existing in the range of ±10°C of the main elution peak is at least 90% of the total amounts of components eluted at a temperature higher than 0°C, and
[II] a propylene-α-olefin copolymer containing 10-90% by weight of a constituent derived from propylene and 10-90% by weight of a constituent derived from α-olefin other than propylene.
本发明公开了一种聚
丙烯组合物,该组合物在低温冲击强度、刚性、耐热性和透明性之间具有优异的平衡性,其特点是含有 20-95% (重量百分比)如下文[I]定义的聚
丙烯和 5-80% (重量百分比)如下文[II]定义的
丙烯-α-烯烃共聚物:
[I]聚
丙烯,其特征是:
(1)异构五聚物(mmmm)的比率为 0.900 - 0.949、
(2) 聚合物链中 2,1- 和 1,3-
丙烯单元的含量为 0-1 摩尔%、
(3) 重量平均分子量(Mw)为 40,000-1,000,000
(4) 平均分子量(Mw)与平均分子量(Mn)之比,即(Mw)/(Mn)为 1.5-3.8,以及
(5) 在连续或逐步提高
邻二氯苯温度至给定温度以测量每个温度下被洗脱的聚
丙烯量的情况下,主洗脱峰的位置为 95-110°C,且在主洗脱峰的±10°C 范围内存在的组分量至少为在高于 0°C 的温度下洗脱的组分总量的 90%,且
[II]一种
丙烯-α-烯烃共聚物,含有 10-90%(按重量计)由
丙烯衍生的成分和 10-90%(按重量计)由
丙烯以外的α-烯烃衍生的成分。