POLYMER SHEET WITH PREDETERMINED FILM AREAS AND INTERCONNECTING FIBROUS AREAS AND ITS METHOD OF MANUFACTURE

摘要

1,206,765. Polymer sheet having film areas interconnected by fibrous areas. JOHNSON & JOHNSON. 9 Nov., 1967 [17 Nov., 1966], No. 51083/67. Heading B5B. [Also in Division D1] Thin sheet material or film comprising a predetermined pattern of film areas of a crystalline orientable thermoplastic polymer, said film areas being integral with and interconnected by fibrous areas of the same polymer may be produced by forming a film (particularly by melt extrusion) of the polymer, and imparting to the film either during its formation or by subsequent treatment a predetermined pattern of areas which resists orientation to a greater extent than does the remainder of the film, stretching the film in a direction and at a stretch ratio sufficiently high to highly orient some areas of the film but not of such magnitude as to fully orient those areas of the film having a greater resistance to orientation and treating the film to fibrillate the highly oriented areas of the film, i.e. to split the film in this area into fibres so that the areas become fibrous. The direction in which the film is stretched may be longitudinal and the treatment for fibrillating the highly oriented areas may be in the transverse direction or vice versa. If the direction in which the film has been stretched prior to fibrillation is longitudinal, the film after fibrillation may be stretched transversely to open the fibrous areas and orient or further orient some film areas. If the film has been stretched transversely prior to fibrillation it may be stretched longitudinally to open the fibrous areas and further orient some film areas. The original film may be formed to have thin areas which are readily orientable and a pattern of thick areas which resist orientation. Alternatively, the original film may have uniform thickness and may subsequently be treated in a predetermined pattern to produce film areas which resist orientation to a greater extent than the remainder of the film. The film polymer may be polyethylene, polypropylene, a polyamide or a polyester.