GB1242740A - Transfer elements and method of making same - Google Patents

Abstract

1,242,740. Squeeze-out carbon &c. papers. COLUMBIA RIBBON & CARBON MFG. CO. Inc. 30 Dec., 1968, No. 61723/68. Heading D2B. [Also in Division C3] A pressure-sensitive transfer element of the squeeze-out type is made by producing an ink layer comprising a non-transferable microporous structure of synthetic thermoplastic polymer, with exudable ink-of colouring matter and oily vehicle in its pores, applying over the ink-releasing surface of the ink layer a coating of a dilute solution of a second synthetic thermoplastic polymer or chlorinated rubber and a blowing agent in a volutile organic solvent, the second polymer being one that leaves an opaque or heterogeneous residue when the solvent is evaporated from a mixed solution of polymer and oily vehicle in a common solvent, and the blowing agent being one that decomposes at a temperature higher than that at which the solvent evaporates, and heating to evaporate the solvent and decompose the blowing agent. In the Example, a film of polyethylene terephthalate is coated with a thin layer of polyvinylidene chloride from solution in methyl ethyl ketone. This is then further coated with a composition of styrene-methyl methacrylate copolymer, mineral oil, refined rapeseed oil, sulphonated vegetable oil, blue toning paste, black toner pigment, ethyl acetate and toluol. The final coating is of polyvinyl acetate and p, p'-oxy-bis (benzenesulphonyl hydrazide) in methyl ethyl ketone. Each coating is dried before the next is applied, the last is heated to activate the blowing agent as well as to evaporate the solvent. Other polymers, solvents and blowing agents for the top coating are referred to, and this coating may also contain plasticizers, fillers or colorants. Reference is also made to inks that comprise magnetic pigments, e.g. iron oxide or colourless colour-forming reagents, and to self-supporting ink-releasing microporous layers coated as above on both surfaces.