| 摘要 |
PURPOSE: To impart an upgraded opacity by blending a first polymer with a second polymer incompatible with the first polymer, and biaxially orienting the film extruded from a molten material. CONSTITUTION: A first polymer of a continuous phase and a second polymer of a discontinuous phase incompatible with the first polymer and deformable in a finely divisible state dispersed in a small amount of a cavity formability in the first polymer are melted, a molten material is extruded, and the film is biaxially oriented. It is most important to densely disperse a small amount of the second polymer of a blend incompatible with the first polymer such as, for example, a polypropylene. A preferable combination includes the polypropylene of film formable polymer and an aromatic polymer or preferably polyalphamethylstyrene of a cavity formable substance. An amount of the aromatic polymer is generally in a range of 5 to 25 wt.% or preferably 10 to 20 wt.% with a weight of resin in a film forming layer as a reference. |
