Negative-toning imaging system with re-imaging capability using 4-(2'-nitrophenyl)-1,4-dihydropyridine compounds

Claim 2

Process for the production of patterns on a substrate bearing a layer of a negative-working, light-sensitive composition comprising at least one 1,4-dihydropyridine compound substituted in the 4 position by a 2'-nitrophenyl ring which becomes tacky and tonable on exposure to actinic radiation, comprising the steps of: (a) exposing said light-sensitive layer imagewise to actinic radiation whereby tacky areas are formed, and, (b) toning said exposed tacky areas with finely divided powders.

Claim 3

Process as recited in claim 1, wherein said exposing and toning steps are repeated several times, using different images for exposure and different powders for toning.

Claim 4

Process according to claim 1, wherein the light-sensitive layer contains at least one 1,4-dihydropyridine compound of the following formula: ##STR2## in which: R is 2'-nitrophenyl, wherein the phenyl radical can be further substituted by alkyl or oxalkyl of 1 to 4 carbon atoms, --OH, halogen, --NH 2 groups; R 1 and R 2 , which can be the same or different, are --CN, --COOR', or --COR', wherein R' represents an alkyl group with 1-11 carbon atoms, which also can be substituted by --OCH 3 or --OC 2 H 5 ; R 3 and R 4 , which can be the same or different, are alkyl of 1 to 4 carbon atoms; R 1 and R 3 taken together may form a 5- and/or or 6-membered carbocyclic or R 2 and R 4 heterocyclic ring containing a carbonyl group.

Claim 5

Process according to claim 1, wherein the light-sensitive composition contains at least one 1,4-dihydropyridine compound chosen from the group consisting of the dimethyl ester, the diethyl ester, and the diisopropyl ester of 2,6-dimethyl-4-(2'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid.

Claim 6

Process according to claim 1, wherein said 1,4-dihydropyridine compound is present in a noncrystalline state in said light-sensitive layer.

Claim 7

Process according to claim 2, wherein said 1,4-dihydropyridine compound is present in a noncrystalline state in said light-sensitive layer.

Claim 8

Process according to claim 3, wherein said 1,4-dihydropyridine compound is present in a noncrystalline state in said light-sensitive layer.

Claim 9

Process according to claim 4, wherein said 1,4-dihydropyridine compound is present in a noncrystalline state in said light-sensitive layer.