Photosensitive printing plate having a light-sensitive coating consisting of a nonprotein colloid, a phosphate, and a chromium compound

Claim 1

A PHOTO-SENSITIVE PLATE COMPRISING A BASE HAVING A PLANOGRAPHIC PRINTING SURFACE AND A SURFACE COATING THEREON CONSISTING OF THE DRIED RESIDUE OF AN AQUEOUS COMPOSITION CONSISTING ESSENTIALLY OF WATER, A NON-PROTEIN HYDROPHILIC ORGANIC FILM-FORMING HYDROCOLLOID OF THE GROUP CONSISTING OF METHYL CELLULOSE, HYDROXYETHYL CELLULOSE, SODIUM CARBOXYMETHYL CELLULOSE, POLYVINYL ALCOHOL, POLYVINYL PYRROLIDONE, SODIUM ACRYLATE, GUM ARABIC, GUM GHATTI AND MESQUITE GUM WHICH IS CAPABLE OF BEING TANNED BY ACTINIC RADIATION IN THE PRESENCE OF AMMONIUM DICHROMATE, A HEXAVALENT CHROMIUM COMPOUND OF THE GROUP CONSISTING OF WATER-SOLUBLE CHROMATES AND DICHROMATES, A WATER-SOLUBLE IONIZABLE PHOSPHATE AND FROM 0% TO 50% BY WEIGHT BASED ON THE WEIGHT OF THE HYDROCOLLIOD OF AN ORGANIC, NORMALLY LIQUID, NON-VOLATILE WATER-REPELLENT SUBSTANCE OF THE GROUP CONSISTING OF NATURAL AND MODIFIED ANIMAL AND VEGETABLE OILS AND MINERAL OILS, THE PH VALUE OF THE COMPOSITION BEING ABOVE 3.0 AND THE PH VALUE OF THE DRIED COATING BEING NOT GREATER THAN 9, THE WEIGHT RATIO OF CHROMIUM COMPOUND TO HYDROCOLLOID BEING WITHIN THE RANGE FROM 1:4 TO 2:1 AND THE PHOSPHATE BEING WITHIN THE RANGE FROM 10% TO 35% OF THE WEIGHT OF THE HYDROCOLLOID.