申请人:Asahi Kasei Chemicals Corporation
公开号:EP1498438A1
公开(公告)日:2005-01-19
The present invention provides a block copolymer or a hydrogenated product thereof excellent in low-temperature shrinkability, natural shrinkability, rigidity and the like, excellent in a balance of physical properties such as blocking resistance, resistance to fusion bonding in hot water, impact resistance and the like, and having a few fish eyes (FE's) caused by gels. Further, the invention provides a heat shrinkable film and a heat shrinkable multilayer film suitable for drink container packaging, cap seals and the like, using such a block copolymer or the hydrogenated product thereof. The invention provides a block copolymer having a weight ratio of a vinyl aromatic hydrocarbon and a conjugated diene of 60/40 to 90/10 and a number average molecular weight measured by gel permeation chromatography (GPC) of 30,000 to 500,000, wherein the vinyl aromatic hydrocarbon constituting the block copolymer has a block rate of from 10 to 90% by weight, the vinyl aromatic hydrocarbon polymer blocks constituting the block copolymer have a peak molecular weight within the molecular weight range of 5,000 to 30,000, and 40 to 80% by weight of the vinyl aromatic hydrocarbon polymer blocks have a molecular weight of 35,000 or less.
本发明提供了一种嵌段共聚物或其氢化产品,具有优异的低温收缩性、自然收缩性、刚性等性能,在耐阻塞性、耐热水熔融粘合性、耐冲击性等物理性能的平衡方面表现出色,并且很少出现由凝胶引起的鱼眼(FE)。此外,本发明还提供了一种热收缩薄膜和一种热收缩多层膜,使用这种嵌段共聚物或其氢化产物,适用于饮料容器包装、瓶盖密封等。本发明提供了一种嵌段共聚物,其乙烯基芳香烃和共轭二烯的重量比为 60/40 至 90/10,凝胶渗透色谱法(GPC)测得的平均分子量为 30,000 至 500,000,其中构成嵌段共聚物的乙烯基芳香烃的嵌段率为 10%至 90%(按重量计)、构成嵌段共聚物的乙烯基芳香烃聚合物嵌段的峰值分子量在 5,000 至 30,000 的分子量范围内,40%至 80%(按重量计)的乙烯基芳香烃聚合物嵌段的分子量在 35,000 或以下。