| 摘要 |
PURPOSE: To obtain an inexpensive gas-permeable film which is hygienic and can prevent the intrusion of foreign matters. CONSTITUTION: A gas-permeable film is a 27μm-thick porous film 1 10 made of an oriented polypropylene film in which a countless number of minute pores 10 are pierced and on one side of which a very thin permeable polypropylene resin membrane 2 with a mean thickness of 5μm is laminated by extrusion- lamination process. The minute pores 10 of the porous film 1 are 0.4mm in diameter and are pierced at intervals of 0.7mm. The thickness of the permeable resin membrane 2 is 5μm on the average and ranges within 3-8μm. Although the pores 10 as vent openings are covered with the permeable resin membrane 2, the gas-permeable effect can be naturally obtained through pin holes and ultra-minute vent openings as the resin membrane 2 is very thin. |
