Lithographic printing plate prepared by photoelectrostatic reproduction, a method for its production and a method for lithographic printing

Claim 1

A LLITHOGRAPH PRINTING PLATE COMPRISING: A BASE SHEET WHICH HAS DIMENSIONS AND TWO OPPOSITE EDGES WHICH ADAPT THE SHEET FOR ATTACHMENT TO THE PLATE CYLINDER OF A LITHOGRAPHIC PRINTING PRESS; A PHOTOELECTRIC FILM COMPRISING A FINELY-DIVIDED, PHOTOCONDUCTIVE, ZINC OXIDE PIGMENT DISPERSED IN A MATRIX OF A RESINOUS, FILM-FORMING MATERIAL WHICH IS INHERENTLY HYDROPHOBIC IN CHARACTER, COVERING ONE SURFACE OF THE SAID BASE SHEET; A HYDROPHOBIC, RESINOUS MATERIAL COVERING PREDETERMINED AREAS OF THE SAID PHOTOELECTROSTATIC FILM IN THE FORM OF AN IMAGE TO BE REPRODUCED BY LITHOGRAPHIC PRINTING, LEAVING EXPOSED AREAS OF THE PHOTOELECTROSTATIC FILM CORRESPONDING TO THE BACKGROUND AREAS OF THE IMAGE TO BE REPRODUCE; AND A SYNERGISTIC COMBINATION OF A POLYMERIC CARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF POLYACRYLIC ACID AND POLYMETHACRYLIC ACID, WITH AN INORGANIC SALT SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL FERROCYANIDES AND ALKALI METAL FERRICYANIDES BONDED TO THE EXPOSED AREAS OF THE PHOTOELECTROSTATIC FILM, CAUSING THE SAID EXPOSED AREAS TO BE HYDROPHILIC IN CHARACTER, WHILE THE SAID RESINOUS MATERIAL FORMING THE IMAGE AREAS REMAINS HYDROPHOBIC IN CHARACTER.