GB956767A - Improvements in and relating to transfer systems - Google Patents

Abstract

956,767. Transfer systems. J. GROAK. Aug. 12,1960 [Aug.17, 1959],No. 28079/59. Heading D2B. A transfer system is prepared by applying to a base sheet B, e.g. paper, a dispersion of a hard brittle resinous material or a substantially unplasticized synthetic resin and drying it to form a frangible layer F of discrete fine particles of size preferably less than 1¢ microns and exhibiting negligible flow properties at normal temperatures, and applying thereover, or to a receiving surface R, e.g. a second paper sheet, an activating layer A composed of predominantly organic thermoplastic material and having an affinity for the resinous material of the frangible layer and for the surface R intended to receive material by transfer from the base sheet B. If desired one or more further layers I, I 1 , I 2 , of synthetic resin dispersion may be applied over the frangible layer and dried, these layers having affinities for layers A and F, and for each other, greater than the affinity of layer F for the base sheet B. More specifically layer F preferably comprises a hard non-ionic or anionic resin e.g. unplasticized polystyrene, polymethyl, methacrylate, which may be strengthened by blending it with a high m.p. acrylate resin, a polymerized terpene resin emulsion or abutadiene copolymer emulsion. The activating layer A may comprise a continuous layer of polyethylene, e.g. a low m.p. polymer emulsion containing 20% solids, plasticized polystyrene, acrylic resins, polymerised terpene resin, polyamides, or copolymers or mixtures of these resins. The intermediate layers I may be formed from an emulsion of polystyrene, ethyl acrylate or polymerised terpene resin, or admixtures thereof. The various layers may be colourless, translucent, white or coloured by added pigment and their application effected by printing, coating, dipping, rolling or spraying. Thus a relatively inner layer may incorporate a record pigment, e.g. carbon black paste, or the base sheet itself may be coloured, and a relatively outer layer a masking pigment, e.g. titanium dioxide. An inner layer may contain a finely divided material, e.g. magnetic Fe 3 O 4 , detectable by physical sensing methods. A reverse system can be prepared in which a coloured base or baselayer is covered by a frangible layer incorporating a masking colour or having a superimposed overlying layer incorporating such. Pressure on the upper sheet will cause the masking colour to be stripped from the base to reveal the colour beneath.