GB1378750A - Apertured film - Google Patents

Abstract

1378750 Apertured film CONSOLIDATEDBATHURST Ltd 23 Nov 1971 [30 Nov 1970] 36435/72 Divided out of 1378749 Heading B5B A molecularly oriented apertured film for incorporation into laminates comprises spaced elongated ribbons defining openings between, the ribbons being oriented in their longitudinal direction and lying in a common plane when the film is flat, the adjacent extremities of those ribbons which extend to the side of the film being integrally interconnected along border portions 70 (Fig. 6). The film may be made by slitting a thermoplastic film (suitable materials being listed) with heated knives and simultaneously or subsequently orienting it at elevated temperature by gripping the border sections and moving them apart by means of a tenter. Preferably the film is slit laterally and is stretched in the direction of the slits so that the ribbons formed by slitting are reduced in width and the openings are formed; the openings may have substantially zero width if the film has been folded or corrugated in the direction of stretch. In specific embodiments laterally slit films are oriented to produce films having 50, 74 and oriented ribbons 52, 74. The slit pattern was constituted by staggered rows of slits in Fig. 4, and by parallel near full-width slits in Fig. 6. The film may be extruded, cast or blown and the heat of formation may be utilized for slitting. Specification 1,378,749 describes and claims methods and apparatus for laminating, which may use the above films.