GB1107341A - Paper - Google Patents

Abstract

Iridescent synthetic thermoplastic resin elements in the form of thin sheets or films are made by the simultaneous extrusion of a plurality of layers of diverse thermoplastic resin materials and subsequently stretching the extrudate until the thickness of the composite sheet and layers therein are reduced to a desired level. Alternatively the composite sheet is made by depositing a plurality of diverse thermoplastic resin materials on a substrate and subsequently stretching them from the substrate. The materials can be deposited using solvents which are solvent for only one of the materials. Desirably the composite sheet is 0.25-10 mils thick and contains at least 10 layers of diverse p resin materials. Each layer is 0.05-5 thick and adjacent layers differ in refractive index by at least 0.03 so as to give the iridescent effect. There can be 100-500 layers in the film for maximum iridescent effect. Iridescence-producing layers can be bonded by transparent layers. Pieces of the iridescent film are incorporated into a paper pulp to produce an iridescent paper.ALSO:A paper has incorporated therein a plurality of thermoplastic synthetic resin elements each of which comprises a transparent body composed of a plurality of generally parallel synthetic resin layers which produce iridescence in the paper. At least 20% of the layers have a thickness of 0.05-5 and adjacent layers differ in refractive index by at least 0.03 iridescence producing layers may be bonded together by transparent layers. The resin elements may have a thickness of 0.25 to 10 mils and may contain at least 10 layers, e.g. 100-500. The elements can be in the form of fibres filaments circles or rectangles or random shapes. The paper may be black, coloured or white and be made from kraft, cotton fibres, fur, asbestos, glass or cellulosic and/or synthetic fibres. The paper is made by mixing a slurry of the elements and fibre pulp, felting then drying. The paper pulp may contain 2-50% (dry wt.) of the resin elements. The paper can be made to show iridescence only on one side.