GB844256A - Improvements in or relating to a method of copying and multiplying documents - Google Patents

Abstract

844,256. Copying documents. D'HAUTERIVE, G. M. G. June 19, 1957 [July 24, 1956], No. 19344/57. Class 98(2) [Also in Group XVI] A printed or written document made with fatty ink is pressed onto a copying surface coated with chemical reagents to form a latent image on the copying surface as a consequence of partial migration of reagent to the document, and the copying surface is treated to form a visible image or a printing plate. In Example 1 an enamelled sheet metal is coated with monochlororesorcin, pressed on the document for 15 to 30 minutes to fix this reagent particularly on the black areas of the document, the latter is removed and the sheet metal constituting the copying surface is pressed against the paper coated from a solution of diazotised 1-amino-2-naphthol-4-sulphonic acid and aluminium sulphate for 30 minutes, when the paper is released and treated with ammonia vapour to yield an image of yellowish white lines on a red background. In Example 2 a glass plate coated with ammonium sulphocyanide is pressed on a document similarly and then on ferric chloride paper to give an image, which may be used as negative for photographic prints. Pyrazolone derivatives may be included with the ferric chloride. Example 3 describes production of a lithographic printing plate from a glass plate coated with aluminium sulphocyanate by similar pressure against a document and subsequent treatment with a specified aqueous liquid after which fatty ink is applied, and in Example 4 such inked glass plate is treated with metal powder adapted to adhere to the ink and make a very opaque image which may be used as photographic negative. Example 5 is generally similar to Example 3 but uses the formate of aluminium instead of sulphocyanate, and in Example 6 a metal powder is sprinkled on the ink-treated plate of Example 5. Other alternatives are indicated. Specification 844,077 is referred to.