| 摘要 |
A uniaxially heat-shrinkable, biaxially oriented, multilayer film having a polypropylene-containing core layer containing at least 70 wt. % of the multilayer film and at least one polyolefin-containing skin layer adjacent the core layer is prepared by biaxially orienting a coextrudate and thereafter orienting the coextrudate by stretching 10 to 40% in the machine direction. The core layer contains isotactic polypropylene, a modifier which reduces the crystallinity of the polypropylene-containing core layer and a nucleating agent. Such modifiers include atactic polypropylene, syndiotactic polypropylene, ethylene-propylene copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 terpolymer, and linear low density polyethylene. The nucleating agent improves long term dimensional stability. The skin layer can be high density polyethylene on both sides or high density polyethylene on one side and isotactic polypropylene on the other side. |
