| 摘要 |
PURPOSE:To raise the permeability of gas without obstructing the permeability and physical properties by a method wherein a nonpermeable hole of a specific depth and a specific mean area is bored at a rate of specific bored density on one side face of a substrate film. CONSTITUTION:A nonpermeable hole of 10<-6>-10<-2>cm<2> in mean hole area, and 1-99.0% as a ratio to thickness of substrate film in depth is bored at a rate of 1-10000 holes/cm<2> in boring density sigma on one side face of the substrate film such as a polyolefin single layer of 10-200mum in thickness or multilayer substrate film or the like by co-extrusion. Further, a product of the S X the sigma meets the relation of the numerical expression, the oxygen gas permeability is improved by 5% or over by being compared with that of a non-bored film, and a haze value is 70% or under to mold a gas permeable film. As a boring method for the nonpermeable hole, there are, for example, plunge rolling, embossing or the like with a roll having cylindrical or needle-shaped projections. |
