GB201882A - Improved manufacture of stencil-sheets for autographic and typewriting duplication purposes - Google Patents

Abstract

201,882. Koreska, W. Aug. 1, 1922, [Convention date]. Varnishes.-A coating-composition for stencil sheets for use in duplicating machines comprises derivatives of cellulose, an oil and a normally solid fatty substance of mineral, vegetable or animal origin. Inorganic or organic esters of cellulose, oxy-cellulose or hydro-cellulose or hydrated cellulose precipitated from solutions of cellulose or cellulose esters may be employed. The composition may also include a mixture of esters and hydrated cellulose such as is generated when nitro-cellulose is partly denitrated. As examples of fatty substances tallow, the fatty acid of cocoanut oil and paraffin residues are given. A volatile solvent is preferably used consisting, for example, of tetrahydronaphthalene or decahydronaphthalene where hydrocarbons or fats are chosen as the fatty substance. Amyl acetate or a mixture of ethyl ether and alcohol may be used if the substance is a fatty acid or a substance soluble in these solvents. To produce a coating consisting wholly or partly of hydrated cellulose, the coating applied to the sheet is treated with a suitable precipitating liquid e.g. a coating comprising nitrocellulose may be softened by partly denitrating it. A specific example of a suitable ccmposition is given as 400 grms. of nitrocellulose, 800 grms. of castor-oil, 1,000 grms. of tallow and 10 litres of amyl acetate.