PHOTOSENSITIVE SHEET MATERIALS

摘要

1479472 Photo-sensitive materials MINNESOTA MINING & Mfg CO 11 July 1974 [12 July 1973] 30859/74 Heading G2C A light-sensitive sheet material which upon exposure to light yields a first reactant which is capable of reacting with a second reactant to produce a visible change, contains (1) a photo-lyzable heat-stable source of hydrogen halide, (2) an acidcleavable adduct of the first reactant with an organic compound containing a vinyl ether linkage, the adduct being capable of yielding the first reactant which is a reducing agent when cleaved with acid and (3) an acid acceptor, as defined below, the amount of acid acceptor being in the range 0À01 to 2À0 moles per mole of the photolyzable source of hydrogen halide and being less than sufficient to retain all of the hydrogen halide liberated by the photolyzable source upon full exposure to light. The acid acceptor comprises (a) a nitrogen-containing organic compound having at least one basic group in which the conjugate acid corresponding to each basic group has a pKa value greater than 4À6 and/or (b) a nitrogencontaining organic compound having at least one basic group in which the conjugate acid corresponding to each basic group has a pKa value greater than 3À3 and in which the compound has no hydrogen-heteroatom bond with dissociation energy less than 85 kilocalories/mole. The first reactant reducing agents are e.g. 4-methoxy-1- naphthol, phenothiazine and hydroquinones. These act as co-reactants for reducible dyes e.g. N,N-diethyl-2-chloro-2'-methylindoaniline or sodium 2,3',6-trichloro-indophenol used as the second reactant. The light-sensitive sheet can also be used in combination with a second sheet containing the second reactant e.g. a reducible metal salt together with a hindered phenol reducing agent and a toner for the silver image. Adducts of the reducing agents can be formed with alkyl vinyl ethers, dihydropyrans and polyvinyl compounds such as glycol divinyl ether and glycerol trivinyl ether. Suitable photolyzable organic halogen compounds include hexabromoethane, tris (tribromomethyl)-s-triazine and ester and urethane derivatives of tribromoethanol e.g. 2,2,2- tribromoethyl-benzoate,-2-furoate, -3-chlorobenzoate, -3,4- or -2,4-dichlorobenzoate, -1- or -2- naphthoate or -N-phenylcarbamate. In Examples piperazine, 1,8-bis (dimethylamino) naphthalene and diphenyl guanidine are used as acid acceptors.