THERMOPLASTISCHE FLUESSIGKEITSDURCHLAESSIGE SCHICHT.

摘要

Absorbent sheet of thermoplastic material, and partic. covering film for absorptive material, has pores in the embossed parts on the underside of the film, the narrowest part of the pores being below the top surface of the film and widening out towards the underside. Pref. in the prodn. a hot plasticated film is placed on a 0.2 mm thick metal plate which has uniformly distributed perforations of dia. about 0.8 mm. The film is initially 0.015-0.07 mm thick. A pressure difference is produced between the sides of the plate causing the film to be pressed/drawn through the perforations and into the form of blisters of dia. larger than that of the perforations. The film cools more rapidly at the metal plate and is therefore wider at the area. The blisters do not burst geometrically equally; consequently the skins of the blisters (=8) are uneven and cracked/split when the film is cooled. The film is easily withdrawn through the perforations but retains those features with their capillarity.