GB1042321A - Transfer sheet - Google Patents

Abstract

A transfer sheet consists of a backing and a coating which comprises a microporous sponge of synthetic resin containing in its pores a non-solvent organic liquid having colouring substances dispersed therein. The coating is applied as an aqueous dispersion, containing the organic liquid in an amount by weight in excess of the synthetic resin. The backing may be of paper or of polyethylene terephthalate, and may have a precoating of polyvinyl acetate or polyvinylidene chloride. The synthetic resin of the coating may be polyvinyl alcohol, polyvinyl acetate, polyvinylidene chloride, polyacrylamide, polyacrylate, polyvinyl-pyrrolidone or a copolymer of vinyl-pyrrolidone with ethyl acrylate or styrene. Mixtures of these resins may be used, particularly mixtures containing polyvinyl alcohol. The dispersion may also contain karaya, tragacanth, guar, okra or locust-bean gum, Irish moss, or egg or blood albumen. The organic liquid may be oleic acid or mixtures of oleic acid and hydrocarbon oils. The colouring substance may be nigrosine, carbon black, alkali blue, or carbon black with toners. The emulsion, after application may be "broken" by heat alone, but this may be accelerated by incorporating small amounts of mineral acids, ammonium chloride, formaldehyde, methylol-urea, methylolmelamine, chromium compounds, cuprammonium hydroxide, titanium lactate or triethanolamine titanate. The transfer coating may also include diatomaceous earth and surface-active agents, e.g. a mixture of polyoxypropylene and polyoxyethylene.