Cross-laminated film material and methods of producing such material

Abstract

Abstract 1316640 Cross-laminated films O B RASMUSSEN 12 June 1970 [13 June 1969 8 July 1969] 28479/70 Heading B5N Cross-laminated film material comprises two oriented polymer films laminated together with their directions of orientation crossing by means of a bonding film there being three substantially uniformly distributed bonding systems, namely (a) the bonding layer is strongly bonded to the one oriented film (the first) but not bonded or weakly bonded to the other (b) the bonding layer is not bonded or weakly bonded to the first oriented film but strongly bonded to the other, and (c) the bonding layer is not bonded or weakly bonded to both oriented films, the areas of the different bonding systems being immediately adjacent with one another with each area (c) generally immediately between areas (a) and (b). The oriented films may be of high density polyethylene and the bonding layer of low density polyethylene. Alternatively the oriented films may be of iso- or syndiotactic polypropylene, polyamide, polyethylene terephthalate, polystyrene, polyvinyl chloride or polyvinylidene esters and the bonding layer may be of high density polyethylene softened by addition of elastomers, soft copolymers of vinylidene chloride, polycaprolactam, polyethylene terephthalate, block copolymers of propylene containing elastomer links, block copolymers of butadiene and styrene, highly plasticized polyvinyl chloride or vinyl chloride-vinyl acetate copolymers. The strong bonds may be produced by thermowelding, by means of a solvent or by means of a two component adhesive and the weak bonds may be produced by means of a pressure sensitive adhesive of low viscosity, e.g. a soft putty comprising a mixture of a material of oily consistency with a finely dispersed powder. The oriented films may be printed with adhesive in the desired pattern of bonds and bonded together with the intermediate layer of unoriented material which may be extruded directly on to them in the nip of laminating rollers. Alternatively the oriented films may be bonded together by extruding the bonding layer on to one of them, effecting lamination by applying variable pressure with rollers at least one of which has an embossed surface and simultaneously or subsequently laminating the other films to the bonding layer. Using this method a bonding layer may also be laminated to the other film using variable pressure prior to laminating the oriented films together or the molten bonding layer may be extruded between the oriented films which are laminated together by applying variable pressure.

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