| 摘要 |
PROBLEM TO BE SOLVED: To guide a required kind of gas into a bag at a required permeability speed, by providing hollows in which the front end is made smaller as it gees to the depth from the surface of a plastic film in the thickness direction and it is still positioned in the plastic film. SOLUTION: A gas-permeability control film 1 is made of a plastic film 2 with a number of hollows. The hollows 3 are typically provided from one side face of the plastic film 2 to the depth in the thickness direction but it is also possible that the hollows are provided at both faces of the plastic film. It is preferable that the film is a flexible plastic film, especially a thermoplastic film as a representative one. The thickness of a gas-permeability control film can be decided by the gas-permeable speed and the strength. It is decided to be 15-40μm for instance. In this case, the hollows are directly made on the plastic film and the aperture 4 on the film is shaped larger than the front end part 4a.
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