GB687808A - An improved duplicating process - Google Patents

Abstract

687,808. Coated paper. NATIONAL CASH REGISTER CO. Dec. 18, 1950. [Dec. 22, 1949] No. 30739/50. Drawings to Specification. Class 96. [Also in Group XVI] A paper sheet for use as a copy sheet in a duplicating process (see Group XVI) is coated on one or both sides throughout its surface with a mixture containing finely divided particles, preferably white, of a solid inorganic material capable of acting as an adsorbent for and reacting with an organic compound, such as crystal violet lactone, to form a coloured mark. 20 per cent by weight of starch is cooked in water for 15 minutes at 200 degrees F., and the mass cooled to room temperature ; 1 part of attapulgite is dispersed, by the use of a ball mill or the equivalent, in 3 parts of water ; 4 parts of the attapulgite dispersion is mixed with 1 part of the starch solution to form the final mixture. Instead of attapulgite, there may be used Halloysite, magnesium trisilicate, or sodium aluminium zeolite material. Alternatively the inorganic material may be incorporated in the paper, being incorporated in the paper pulp stock as part of the furnish. In another form, the sheet is sensitised by treating it with a solution of tannic acid and drying it, this being suitable where the organic compound is furric ammonium sulphate.