GB958097A - Method and composition for coating paper - Google Patents

Abstract

A paper coating composition comprises water, inorganic pigment, a proteinaceous bonding agent and a water-soluble electrolyte capable of coagulating said bonding agent, said composition being a stable liquid up to 30 DEG C. and being coagulatable by heating to 30 DEG to 95 DEG C. The bonding agent may be milk casein or soybean protein. Pigments specified are clay, titanium white, barium sulphate, and calcium carbonate. The electrolyte may be the water-soluble acids, salts or bases, the solutions of which have a cation such as Li+, Na+, K+, Pb++, Za++, Mg++, Ca++, Sr++, Ba++, Al+++, H+ and NH4+, and an anion such as SO4=, F-, Cl-, Br-, -I, NO3-, CNS-, PO4­ and OH-; organic acids such as formic, acetic, tartaric, citric, lactic and phthalic acids; amines such as ethylenediamine, monoethanolamine, triphenylamine and diethylamine; cationic surface active agents such as an amine-formaldehyde polymer and Hyamine which mainly contains di-isobutyl-cresoxy-ethoxy - ethyl dimethyl - beuryl ammonium chloride; anionic surface active agents such as dodecyl sodium sulphate, turkey red oil and potassium stearate; and amphoteric surface-active agents such as Nissan Anon BT which mainly contains cetyl betaine. In the examples the compositions comprise water, milk, casein, or soybean protein, dicyandiamide, clay, sodium pyrophosphate, and (1) anhydrous barium chloride, ammonium stearate, sodium hydroxide and tributyl phosphate, (2), (3) and (4) anhydrous calcium chloride, sodium hydroxide, ammonium stearate, gum arabic and styrenebutadiene latex, (5) sodium hydroxide, formic acid and tributyl phosphate, (6) hydrochloric acid, dodecyl sodium sulphate, paraffin wax and octanol, (7) ammonium stearate, zinc chloride and octanol, (8) hydrochloric acid, ethylene diamine, paraffin wax and octanol (9) sodium hydroxide, titanium dioxide, ammonium stearate, dicyandiamide - formaldehyde polymer and octanol, (10) gelatin, sodium hydroxide, potassium oleate, or (11) sodium stearate and sodium hydroxide. Other substances which may be present are starch, carboxymethyl cellulose and polyvinyl alcohol. Specification 331,578 is referred to.ALSO:Paper is coated with a liquid coating composition comprising water, inorganic pigment, proteinaceous bonding agent and a water-soluble electrolyte capable of coagulating said bonding agent, said composition being stable up to 30 DEG C., and being coagulatable by heating to 30-95 DEG C., and the composition is coagulated. The coated paper may be pressed, e.g. by passing between a rubber covered roller and a rotating chromium plated drum which may be heated, passed through a bath of boiling water and dried. Another coating may be applied to the coated paper. The bonding agent may be milk casein or soybean protein to which may be added gelatin, gum arabic, starch, carboxymethylcellulose or polyvinyl alcohol. The pigment may be clay, titanium dioxide, barium sulphate and calcium carbonate. The electrolyte may be the water-soluble acids, salts or bases, the solutions of which have a cation such as Li+, Na+, K+, Pb++, Zn++, Mg++, Ca++, Sr++, Ba++, Al+++, H+ and NH4+ and an anion such as SO4=, F-, Cl-, Br-, I-, NO3-, CNS-, PO4­ and OH-; organic acids such as formic, acetic, tartaric, citric, lactic and phthalic acids; amines such as ethylenediamine, monoethanolamine, triphenylamine and diethylamine; and cationic, anionic and amphoteric surface active agents. Specification 331,578 is referred to.