Use of carboxyl group-containing acetal polymers in light-sensitive compositions and lithographic printing plates

A process of forming a lithographic printing plate comprising the steps of:

• a) imagewise exposing a photosensitive composition disposed on a substrate to radiation, wherein the photosensitive composition comprises:
• (i) at least one diazonium polycondensate, at least one system capable of free radical polymerization and comprising photoinitiators and unsaturated compounds which are capable of free radical polymerization or at least one hybrid system comprising a diazonium polycondensate and a system capable of free radical polymerization and comprising photoinitiators and unsaturated compounds which are capable of free radical polymerization, and
• (ii) at least one binder comprising units A, B, C and D, A being present in an amount of from 0.1 to 25 mol % and corresponding to the formula
• in which R1 is a hydrogen atom, an aliphatic hydrocarbon radical having 1 to 4 carbon atoms which may be unsubstituted or substituted with at least one carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, or an aromatic radical which may be unsubstituted or substituted with at least one alkyl group, carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, preferably a methyl group,
• B being present in an amount of from 0.1 to 60 mol % and corresponding to the formula
• C being present in an amount of from 10 to 80 mol % and corresponding to the formula
• in which R2 is hydrogen atom, an alkyl radical having from 1 to 10 carbon atoms which may be unsubstituted or substituted with at least one carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, or an aryl radical which may be unsubstituted or substituted with at least one alkyl group, carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, it being possible for this unit to be present several times with different radicals R2 independently of one another, and
• D being present in an amount of from 1 to 20 mol % and corresponding to the formula
• in which R3 is a hydrogen atom or alkyl radical having 1 to 10 carbon atoms, which may be unsubstituted or substituted by a carboxyl group;
• and
• b) developing the photosensitive composition.

A printing plate coated with a photosensitive composition comprising:

• (i) at least one diazonium polycondensate, at least one system capable of free radical polymerization and comprising photoinitiators and unsaturated compounds which are capable of free radical polymerization or at least one hybrid system comprising a diazonium polycondensate and a system capable of free radical polymerization and comprising photoinitiators and unsaturated compounds which are capable of free radical polymerization, and
• (ii) at least one binder comprising units A, B, C and D, A being present in an amount of from 0.1 to 25 mol % and corresponding to the formula
• in which R1 is a hydrogen atom, an aliphatic hydrocarbon radical having 1 to 4 carbon atoms which may be unsubstituted or substituted with at least one carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, or an aromatic radical which may be unsubstituted or substituted with at least one alkyl group, carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, preferably a methyl group,
• B being present in an amount of from 0.1 to 60 mol % and corresponding to the formula
• C being present in an amount of from 10 to 80 mol % and corresponding to the formula
• in which R2 is a hydrogen atom, an alkyl radical having from 1 to 10 carbon atoms which may be unsubstituted or substituted with at least one carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, or an aryl radical which may be unsubstituted or substituted with at least one alkyl group, carboxyl group, sulfonic acid group, hydroxyl group or at least one halogen atom, it being possible for this unit to be present several times with different radicals R2 independently of one another, and
• D being present in an amount of from 1 to 20 mol % and corresponding to the formula
• in which R3 is a hydrogen atom or alkyl radical having 1 to 10 carbon atoms, which may be unsubstituted or substituted by a carboxyl group.