GB1416990A - Transfer sheet material - Google Patents

Abstract

1416990 Transfer sheet WIGGINS TEAPE LTD 20 Feb 1973 [21 Dec 1971] 59214/71 Heading D2B A transfer sheet material comprises a base sheet having on one surface a coating containing one or more colour formers each having the formula where A and B are optionally substituted 1, 4-arylene residues, X 1 is hydroxy, alkoxy or optionally substituted amino radical, and X 2 is hydrogen, hydroxy or optionally substituted amino radical. A and B are preferably 1, 4- phenylene residues, and the substituents in A, B may be alkyl, amino, dialkylamino, hydroxy, alkoxy, carboxy and sulpho. The substituents in A, B may also bridge A and B to produce a compound of formula: where Z represents a direct link, oxygen, sulphur or -NR-, where R is hydrogen or an optionally substituted alkyl, aryl or aralkyl radical e.g. 2-methyl benzyl, benzyl or methyl. X 1 and X 2 may have the formula -NR 1 R 2 where R 1 and R 2 are hydrogen or an optionally substituted alkyl, aralkyl oraryl radical. Examples of R 1 and R 2 are methyl, ethyl, propyl, butyl, #-hydroxyethyl, #-chloroethyl, 4-methoxy-benzyl, 2 methylbenzyl, benzyl, 2-methylphenyl, 4 - methylphenyl, 3 - chlorophenyl, naphth-2-yl, and phenyl. The colour former may be in the form of a salt with HCI, HBr, HNO 3 or H 2 SO 4 or with a Group IA metal, a Group IIA metal, optionally substituted ammonium, optionally substituted hydrazine, optionally substituted hydroxylamine, optionally substituted cyanidine, or a heterocyclic base. The colour formers are leuco compounds of dyes of the indamine, azine, oxazine, thiazine and carbazole series and may be prepared by reduction of such dyes. Example 1 describes the preparation of leuco gallocyanine from gallocyanine and Table 1 lists other dyes which may be reduced to produce a colour former for use in the present invention. Tables 2 and 3 list examples of colour formers for use in spirit duplicating and pressure sensitive copying systems respectively. The base sheet may be of paper, polypropylene or polyethylene terephthalate. The colour former may be evenly distributed throughout the coating, or may be present in solution in microcapsules in the coating. The colour former may be used with an acid clay developer. In a pressure sensitive copying system, the coated surface of the transfer sheet is placed in contact with a surface of a copy sheet carrying the developer. If a plurality of copies are required intermediate copy sheets are interposed between the two sheets, each intermediate copy sheet having on on side a colour former as above, and on the other the developer. In a hectographic copying system, the colour former may be mixed with castor oil, 10 ethyl cellulose and toluene to form the coating material, and the developer may be attapulgite or montmorillonite clay.