GB1073454A - A method of making a carbonless transfer element - Google Patents

Abstract

A pressure-sensitive "carbonless" transfer element is made by dissolving a colour precursor in an organic solvent, dispersing this solution in a solution of a film-forming polymer or resin, coating this dispersion on to a substrate and drying to form a porous layer of film-former containing droplets of precursor solution in its pores. The colour precursor may be a triaryl-lactone, a leuco-methylene blue, a leucauramine or a triarylmethane-leucauramine. The film-former may be polyvinyl alcohol, polyvinyl chloride, polyvinyl-pyrrolidone, gelatine, sodium carboxymethylcellulose, ethylcellulose or polystyrene. The dispersion may also contain a plasticizer for the film-former, e.g. glycerol, ethylene glycol or sorbitol, or a dispersing agent, e.g. an alkyl aryl sulphonate or a polyoxyethylene derivative. In the Examples: (1) an aromatic amine colour precursor is dissolved in mineral oil, polyvinyl alcohol and sorbitol are dissolved in water and the first solution is dispersed in the second; (2) an aromatic amine precursor is dissolved in chlorinated polyphenyl and this solution is dispersed in a solution of ethylcellulose in acetone; (3 and 4) as Example 2, except that different quantities of nitrocellulose are added to the precursor-ethylcellulose dispersion; (5) the precursor is dissolved in ethylene glycol monomethyl ether ricinoleate, polystyrene is dissolved in a mixture of methyl ethyl ketone, n-butanol, ethyl acetate, ethylene glycol monomethyl ether ricinoleate and toluene and the first solution is dispersed in the second; and (6) as Example 5 except that nitrocellulose is added to the dispersion.ALSO:A pressure-sensitive "carbonless" transfer element is made by dissolving a colour precursor in an organic solvent, dispersing this solution in a solution of a film-forming polymer or resin, coating this dispersion on to a substrate and drying to from a porous layer of film-former containing droplets of precursor solution in its pores. The colour precursor may be a triaryl-lactone, a leuco-methylene blue, a leucquaramine or a triarylmethaneleucauramine. The film-former may be polyvinyl alcohol, polyvinyl chloride, polyvinylpyrrolidone, gelatin, sodium carboxymethylcellulose ethylcellulose or polystyrene. The dispersion may also contain a plasticizer for the film-former, e.g. glycerol, ethylene glycol or sorbitol, or a dispersing agent, e.g. an alkyl aryl sulphonate or a polyoxyethylene derivative. The substrate may be of paper, metal or foil, and may be coated on its other side with a developing agent for the colour precursor, e.g. an acid clay or pyrogenic colloidal silica in a binder. A release layer of a polymer or resin may be coated on to the substrate before the dispersion. The polymers of the release layer and the porous layer are chosen to have poor adhesion to one another; if one is hydrophilic the other may be hydropholic and vice versa. A substance e.g. nitrocellulose may be incorporated in one or more layers to increase the adhesion between them. In the Examples: (1) an aromatic amine precursor is dissolved in mineral oil, polyvinyl alcohol and sorbitol are dissolved in water, the first solution is dispersed in the second and the dispersion is coated on to paper; (2) paper is coated on one side with an aqueous solution of starch containing pyrogenic colloidal silica, the other side of the paper is coated with cellulose acetate from solution in acetone, an aromatic amine precursor is dissolved in chlorinated polyphenyl, this solution is dispersed in a solution of ethylcellulose in acetone, and this dispersion is coated on to the film of cellulose acetate, several sheets are superposed when the top sheet is written upon, copies are formed on all the others; (3 and 4) as Example 2, except that different quantities of nitrocellulose are added to the precursor-ethylcellulose dispersion; (5) the precursor is dissolved in ethylene glycol monomethyl ether ricinoleate, polystyrene is dissolved in a mixture of methyl ethyl ketone, n-butanol, ethyl acetate, ethylene glycol monomethyl ether ricinoleate and toluene, the first solution is dispersed in the second and the dispersion is coated on to a cellulose acetate foil; and (6) as Example 5 except that nitrocellulose is added to the dispersion.