| 摘要 |
Copolymers of ethylene and ±-olefins, having
(a) a density in the range 0.900 - 0.940 g/cm 3 ,
(b) a melt index Ml 2 (2.16 kg, 190°C) in the range of 0.01 - 50 g/10 min,
(c) a melt elastic modulus G' (G"= 500 Pa) in the range 20 to 150 Pa, and
(d) a tear strength (MD) of ‰¥ 220 g, a tear strength (TD) of ‰¥ 470 g, and a dart impact of ‰¥ 1800 g of a blown film having a thickness of 25mm produced from the copolymer; where MD is referred to the machine direction and TD is the transverse direction of the blown film
are suitably prepared in the gas phase by use of a supported metallocene catalyst system. Particularly suitable are copolymers of ethylene and 1-octene and the resultant blown films show improved processsability and exhibit an improved balance of film properties of dart impact and tear strength. |
