Printing plates comprising hydrophobic resisto formed by crosslinking photopolymerized hydrophilic monomers with an isocyanate

Claim 1

THE PROCESS OF PRODUCING A NEGATIVE WORKING METAL LITHOGRAPHIC PLATE HAVING ON ONE SURFACE INK-RECEPTIVE POLYMERIC PRINTING PORTIONS AND WATER-RECEPTIVE, NONPRINTING PORTIONS DEFINED BY THE METAL OF SAID SURFACE WHICH COMPRISES COATING A METAL BASE WITH A PHOTOPOLYMERIZABLE COMPOSITION OF A COLLOIDAL CARRIER HAVING DISPERSED THEREIN AN ETHYENICALLY UNSATURATED MONOMER HAVING A CH2=C< GROUP AND CONTAINING A HYDROXYL GROUP, SAID MONOMER BEING CAPABLE OF YIELDING ON POLYMERIZATION A HYDROPHILIC POLYMER CONTAINING HYDROXYL GROUPS, IRRADIATING SAID COMPOSITION WITH ACTINIC LIGHT UNDERNEATH A PATTERN TO POLYMERIZE SAID MONOMER IN THE EXPOSED AREAS TO SAID HYDROPHILIC POLYMER, SELECTIVELY WASHING OUT THE UNEXPOSED AREAS UNTIL THE METAL SURFACE OF SAID PLATE IS VISIBLE TO FORM IN SAID AREAS SAID WATER-RECEPTIVE NONPRINTING PORTIONS AND REACTRING SAID HYDROPHILIC POLYMER IN THE EXPOSED AREAS WITH AN ISOCYANATE OF THE FORMULA R(NCO)M WHEREIN R IS SELECTED FROM THE CLASS CONSISTING OF ARYL AND ARALYKYL AND M IS A WHOLE NUMBER NOT GREATER THAN 2, UNTIL SAID POLYMER IS CONVERTED INTO SAID INKRECEPTIVE POLYMERIC PRINTING PORTIONS.