Abstract: Photosensitive compositions, useful in lithographic printing plates which can be developed with aqueous developing solutions, comprise a diazo resin and an acid-substituted ternary acetal polymer which functions as a polymeric binder. The acid-substituted ternary acetal polymers are comprised of recurring units which include three six-membered cyclic acetal groups, one of which is unsubstituted or substituted with an alkyl or hydroxyalkyl group, another of which is substituted with an aromatic or heterocyclic moiety, and a third of which is substituted with an acid group, an acid-substituted alkyl group or an acid-substituted aryl group.

Abstract: Novel acid-substituted ternary acetal polymers are comprised of recurring units which include three six-membered cyclic acetal groups, one of which is unsubstituted or substituted with an alkyl or hydroxyalkyl group, another of which is substituted with an aromatic or heterocyclic moiety, and a third of which is substituted with an acid group, an acid-substituted alkyl group or an acid-substituted aryl group. The acid-substituted ternary acetal polymers are advantageously employed in photosensitive compositions in which they are utilized in combination with diazo resins. Such photosensitive compositions are especially well adapted for use in lithographic printing plates which can be developed with aqueous developing solutions.