Patent ID: 7318995

Claim:
A method of making a negative-working lithographic printing plate comprising the steps of: (1) providing a lithographic printing plate precursor comprising on a grained and anodized aluminum support, having a hydrophilic surface, a coating comprising polymer particles and an infrared light absorbing agent; (2) exposing said coating to heat, thereby inducing coalescence of said polymer particles at exposed areas of said coating; and (3) developing said precursor by applying a gum solution to said coating, thereby removing non-exposed areas of said coating from said support; wherein said polymer particles prior to exposure are core-shell particles comprising a hydrophobic heat-softenable core comprising a heat-softenable polymer having a minimum film-forming temperature above ambient temperature and a hydrophilic shell, and wherein the shell comprises a hydrophilic polymer which is soluble in water at neutral pH or at a pH ranging between 5 and 7.