GB990123A - Improvements in laminated materials and in processes for their production - Google Patents

Abstract

990,123. Laminates. CELLOPHANE INVESTMENT CO. Ltd. June 5, 1962 [June 9, 1961], No. 21708/62. Heading B5N. A strong transparent laminated sheet, suitable for use in packaging, comprises layers of a substantially impervious polymer, such as polyethylene or another polyolefin, or of polyvinylidene chloride, a vinyl chloride polymer or copolymer, or a polyurethane elastomer, coated on their internal faces with a thermosetting resin such as a polyurethane or an epoxy resin. The reagents for forming the thermosetting resin are applied as a solution to the appropriate sides of the sheets of polyethylene or the like, the solvent is evaporated, and the coated sheets stuck together, to form the laminated structure, by calendering at high temperature. The thermosetting resin is then cured by a further application of heat during which the layers of polyethylene &c. become plastic. The laminated sheet is finally quenched between two cooled rollers to render it substantially transparent. The thermosetting resin is such that when cured it has sufficient strength to support the plastic layers of polyethylene &c. before quenching. Suitable thermosetting resin-forming reagents for use with polyethylene comprise (a) a vinyl chloride/vinylidene chloride copolymer, an organic isocyanate, a polyurethane, methyl ethyl ketone, ethyl acetate and trichlorethylene or toluene; (b) a similar composition in which the polyurethane is replaced by an epoxy resin. The polythene layers may be flamed or otherwise treated to render them adhesive.