FREE RADICAL PHOTOGRAPHIC SYSTEM CONTAINING A PYRYLIUM DYE FORMER

1398265 Print-out photographic organic polyhalogen material AGFA-GEVAERT 10 Aug 1972 [14 Sept 1971] 42802/71 Heading G2C [Also in Divisions C2 and C3] A photo-sensitive material comprising in intimate admixture (A) at least one organic polyhalogen compound of which a halogen containing radical can be separated photolytically and (B) at least of colour-forming compound of the formula:- wherein R 1 is optionally substituted aliphatic or aryl group or together with R completes a cyclohexylen-2-one ring; R' is H, methyl, phenoxy or optionally substituted phenyl; Z 1 completes a homocyclic ring or ring system which may be substituted; Z 2 completes a homocyclic ring which may be substituted; R 2 is 1-5C alkyl; and n is 2 or 3. The material may contain a polymer containing recurring units of the formula:- where Z is S when present; A is a single bond or a divalent hydrocarbon group; R 1 is H or methyl; R 2 is H, methyl or ethyl; each of Q 1 and Q 2 is H or together complete an adjacent carbocyclic ring or ring system which may be substituted; each of Q 3 and Q4 is H or together complete an adjacent carbocyclic ring or ring system which may be substituted; and n is 1 or 2, a compound of the formula:- where R 1 , R 2 and R 3 are each optionally substituted aryl, or a sterically hindered phenol antifoggant. The material may contain a hydrophobic binder. The material may contain Pb, Hg, Bi, Ba and/or W to render it sensitive to X-rays, ultraviolet radiation being generated by exposure to X-rays. A visible image is produced by (a) imagewise exposure to actinic radiation to give a print-out negative image, (b) imagewise exposure to actinic radiation sufficient only to produce a latent image and then overall exposure to render the latent image visible or (c) a low-level overall exposure to actinic radiation followed by imagewise exposure to give a visible image. The material may be heated, e.g. by overall infrared exposure, during imagewise exposure. The material may, after a visible image has been formed, be heated to increase image density or stabilize the image. The visible image may be stabilized by treatment with solvents to remove the organic polyhalogen.