申请人:SUMITOMO CHEMICAL COMPANY, LIMITED
公开号:EP0586109A2
公开(公告)日:1994-03-09
A crystalline propylene polymer (100 parts by wt) which can be a random copolymer with an olefin, having a molecular weight distribution (Mw/Mn) of less than 5.0 and preferably a melt flow rate of 3.0 to 50 g/10 minutes, is compounded with 0.001 to 1.0 part of a crystal nucleating agent which can be inorganic, organic or polymeric (e.g. talc, an aromatic carboxylic acid metal salt or a vinyl cycloalkane polymer), preferably of mean particle size 6.0 µm or less, such that the crystallization temperature of the composition is at least 1.5°C, preferably 2.0°C, higher than that of the propylene polymer. Synthesis of the polymer is described with a Ziegler-Natta catalyst.
The composition is used for melt-extrusion of a film of thickness 10 to 500 µm by a T-die film-forming method in which the surface temperature of the cooling roll is at least 50°C. Multilayer films can be co-extruded.
The films have good transparency, which has low dependency on the film thickness, and are useful for packaging.
在结晶丙烯聚合物(100 重量份)中加入 0.001 至 1.0 份晶核剂(可以是无机物、有机物或聚合 物,如滑石粉、芳香族羧酸金属盐或乙烯基环烷聚合物),其分子量分布 (Mw/Mn) 小于 5.0,熔体流动速率最好为 3.0 至 50 克/10 分钟。例如滑石粉、芳香族羧酸金属盐或乙烯基环烷聚合物),其平均粒径最好小于或等于 6.0 微米,使组合物的结晶温度至少比丙烯聚合物的结晶温度高 1.5°C,最好高 2.0°C。聚合物的合成采用齐格勒-纳塔催化剂。
该组合物用于通过 T 型模压成膜法熔融挤出厚度为 10 至 500 微米的薄膜,其中冷却辊的表面温度至少为 50°C。多层薄膜可以共挤。
这种薄膜具有良好的透明度,与薄膜厚度的关系不大,可用于包装。