GB1384535A - Information-wise photo-activated bleaching - Google Patents

Abstract

1384535 Photographic bleach-out materials AGFA-GEVAERT 5 April 1972 [15 April 1971] 9555/71 Heading G2C A photographic bleach-out material comprises a supported or self-supporting layer of a binder and photo-sensitive composition comprising (i) an organic polyhalogen yielding free radicals on exposure (ii) a cyanine, fluorescein or rhodamine dye or a coloured quinodimethane compound capable of being bleached by the free radicals and (iii) a compound accelerating the bleaching and being of one of the following formulae I-IX: (VII) R 4 -N=N-SO 2 -R 5 , (II) D-Z-Y-Z-D:- wherein D is a dialkylamino group, R is H or alkyl, Z is phenylene or vinylphenylene, X is oxygen or sulphur, Y is an electron attracting group e.g. -CO-, -CS-, -SO-, -SO 2 - or -CO-CO-, Q 1 completes a ring in which the group CX is linked through a conjugated system to the dialkylamine group, Q 2 completes a ring wherein # D-Z-C- is linked through a conjugated system to an electron-attracting group or completes an electronegative heterocyclic ring, R 1 and R 2 and R 3 are alkyl, Q is an aromatic ring or ring system, R 4 and R 5 are aryl or substituted aryl, Q 3 is -SO 2 - or-CO-, X 1 is oxygen, sulphur or =N-R<SP>1</SP> where R<SP>1</SP> is H or aryl and Z completes a 5- or 6- membered heterocyclic ring or ring system. Specified binders are cellulose ethers and esters, vinyl polymers and synthetic rubbers. In the examples, the compositions using ethyl cellulose as binder were coated on a polyester support and imagewise exposed to bleed out the exposed areas. The image is fixed by heating to between 90‹ and 200‹C.