GB752336A - Improvements in or relating to stencil duplicating inks - Google Patents

Abstract

Water-based tinctorial stencil duplicating inks contain complex double salts of a compound of high molecular weight, e.g. cellulose esters or ethers, proteins, polysaccharides, polyalkyl acrylates, styrene-maleic anhydride copolymers, caseinates, lignates and alginates, in which one of the salt-forming components is ammonium and the other is a metal capable of forming an insoluble salt with the high molecular compound, e.g. copper, nickel, cadmium, zinc, iron or aluminium. On transfer of the ink composition through the stencil openings to the impression medium to form the copy, the ammonia component is removed by volatilization on drying to leave the corresponding highly insoluble bivalent metal salt of the bodying agent. Specified bodying agents are zinc ammonium polyacrylate, copper ammonium methyl methacrylate, aluminium ammonium ethyl acrylate, cadmium ammonium carboxy methyl cellulose, zinc ammonium carboxymethyl cellulose, zinc ammonium caseinate or alginate, iron ammonium pectate, copper ammonium alginate, aluminium ammonium alginate; the salts should be added in sufficient amount to give a composition having a viscosity of 35-150 seconds (Stormer Viscosimeter), e.g. 1-15 per cent by wt. of the composition of salts of polyacrylates or 0.5-10 per cent of complex alginates. Colouring agents specified are Nigrosine, triphenylmethane, Rhodamine B, thioflavine, auramine, sulphonated triphenylmethane, quinone imide and xanthene dyes; sodium sulphonate derivatives of nitro-azo, pyrazoline, quinoline, triphenylmethane, diphenyl naphthyl methane, azine, xanthene, and anthraquinone groups; pigments specified are lamp black, malachite green, iron blue, cadmium yellow. Wetting agents may be added, e.g. dioctyl ester of sodium sulphosuccinate, quaternary ammonium compounds, sulphonated ethers, fatty alcohol sulphonates, polyoxyethylene derivatives of fatty acids; polyhydric alcohols, e.g. glycols, and alkylolamines may be added as humectants. Insolubilization of the bodying agents may be further increased by the addition of aldehydes, e.g. glyoxal or pyruvic aldehyde. The examples specify the following aqueous mixtures: Example 1 5 per cent Nigrosine J (water-soluble dye), 2 per cent wetting agent (dioctyl ester of sodium sulphosuccinate, 50 per cent solution), 1.5 per cent glyoxal (30 per cent solution), 35 per cent ethylene glycol, 56.5 per cent zinc ammonium carboxy methyl cellulose (2.5 per cent solution in water); Example 2 5 per cent Nigrosine J (water-soluble dye), 1 per cent wetting agent, 1.5 per cent glyoxal (30 per cent solution), 35 per cent ethylene glycol, 57.5 per cent zinc ammonium polyacrylate (2.5 per cent solution in water); Example 3 15 per cent Aquablac (40 per cent carbon black dispersed in aqueous medium), 1 per cent wetting agent, 30 per cent ethylene glycol, 3 per cent zinc ammonium alginate, 51 per cent water. Specifications 676,373, 742,301 and 752,337 are referred to.