| 摘要 |
PROBLEM TO BE SOLVED: To improve the fitness of bag-making and filling workability of a film and also its transparency and rigidity by a method wherein the film is made of a polypropylene polymer or an ethylene-propylene copolymer, the content of the ethylene in which is specified, and the range of its longitudinal percent of stretch is specified. SOLUTION: This biaxially stretched polypropylene film is made of a polypropylene polymer or an ethylene-propylene copolymer, the ethylene content of which is 1.0 wt.% or less. And, by setting its longitudinal percentage of stretch is set to be in the range of 350-450%, the elongation at break in the flow direction of a film is set to be 200% or more. The polyolefin-based copolymer used may well contain anα-olefin except the ethylene and propylene such as a butene as a copolymer component as long as no physical properties of the polyolefin-based copolymer is impaired. The melt index of the polyolefin- based copolymer used is preferably set to be the range of 1-10 g/10 min for giving a favorable film-formability to the film. |
