GB951645A - Improvements in sheets adapted for producing copies without the use of carbon papers, and the manufacture thereof - Google Patents

Abstract

In sheets for producing copies, each sheet has a backing support and a substantially wax-free and oil-free dye layer, the dye-delivery side of one sheet is adjacent the dye-receiving side of the next sheet, and there is provided on the dye-delivery side or on the dye-receiving side, a layer of adhesive plastics material so that dye particles transferred to the dye-receiving sheet under the influence of pressure adhere to the surface thereof in a firm and non-staining manner by means of the adhesive plastics material. The adhesive plastics material may be provided alone or in combination with additives such as binding or softening agents. The adhesive plastics materials should be such that they do not adhere under influence of a weak surface pressure, e.g. finger pressure, but develop an intense adhesive power when subjected to an increased pressure exerted by a mechanical instrument. The backing support may be composed of paper, plastic, glass, viscose, cellulose-derived or metal foils, including webs, rolls and folded e.g. zig-zag, and multi-layer sheets; these may be rendered opaque and only partly covered by dye-delivering and dye-receiving layers. An interposed layer of white pigment may be placed under the dye-delivering or dye-receiving layer so that the colour does not shine through to the other side. Adhesive plastics materials specifically mentioned: polyethylene; polyvinyl alcohols, ethers, acetates, acetals, propionates, propionales, butyrates, butyrales, and chlorides or copolymerisates of these; acrylates, methacrylates; polystyrenes; polyamides; polypropylene; alkyd resins and phthalate plastics; and cellulose derivatives. According to examples, the layer of adhesive plastic material consisted of (i) a dispersion in carbon tetrachloride or light benzine of polyethylenes of molecular weights between ca. 1500-2000 having, in general, melting temperatures of about 90-110 DEG C., or mixtures of softer or harder polyethylenes, or (ii) included the following ingredients: lithopone, silicic acid, polystyrene, dibutyl phthalate and ethyl acetate, and was applied to the extent of 1-2 grams per square metre of surface. Ingredients for the dye-delivering layer included: black oxide of iron, silicic acid, polystyrene, polyvinyl acetate, polyvinyl methylether, oleyl alcohol, methyl and ethyl alcohols and ethyl acetate. Ingredients for the dye-receiving layer included: titanium dioxide silicic acid polyvinyl methyl ether and methyl alcohol. In certain examples, the dye-receiving layer was provided with a thin covering of polyethylene glycol instead of the adhesive plastics material.