GB1350032A - Method and system for forming coloured marks - Google Patents

Abstract

1350032 Record sheets NATIONAL CASH REGISTER CO 13 June 1972 [22 June 1971] 27489/72 Heading D2B [Also in Division B6] A method of forming coloured marks on a record sheet carrying microcapsules having walls of hydrophilic polymer material and each containing a water-immiscible liquid and at least one colourless chromogenic material comprises applying thereto a water-miseible solvent containing an electron-acceptor material of the Lewis acid type such that the applied solvent diffuses through the walls of the capsules replacing part of the capsule contents thereby causing reaction to occur between the chromogenic and electron-acceptor materials to form a coloured mark without capsule rupture. In the alternative, the electronacceptor material may not be contained in the water-miscible solvent, but may be on the record sheet isolated from the chromogenic material. The solvent may be applied by dipping, brushing, wiping or spraying. A felt-tip marker or aerosol sprayer may be used for applying the solvent. The base of the record sheet may be made of paper or an organic polymeric film. The chromogenic material may be Crystal Violet Lactone, benzoyl leuco methylene blue, a fluoran derivative, 3, 3-bis (1-ethyl-2-methyl-indol-3-yl) phthalide (or the corresponding 1-benzyl derivative) or 9-diethylaminospiro [1, 2-4-benzo-(a)]xanthene-1, 2, 1'- phthalide]. The electron-acceptor material may be a phenolic polymer, phenol-acetylene polymer, maleic acid-rosin resin, partially or wholly hydrolysed styrene-maleic anhydride copolymer or ethylene-maleic anhydride copolymer, carboxy polymethylene, wholly or partially hydrolysed vinyl methyl ether-maleic anhydride copolymer, kaolin, attapulgite, bentonite, silica gel, or a zeolite. According to one embodiment, the capsules and electron-acceptor material may be coated on a record sheet so as to form a colourless design, this being subsequently developed by application of the water-miscible solvent. Alternatively, capsules containing different chromogenic materials may be applied to the base sheet such that application of solvent produces blocks of different colour.