Gelatin printing plates with thermoplastic underlayer

Claim 1

A METHOD OF RELIEF PRINTING WHICH COMPRISES PROVIDING A SENSITIZED PLATE STOCK FORMED OF A SHEET OF BASE MATERIAL HAVING FIXED THERETO A LAYER OF WATER-INSOLUBLE SYNTHETIC THERMOPLASTIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF POLYVINYL CHLORIDE, POLYSTYRENE AND CELLULOSE ACETATE ABOUT 0.01 INCH IN THICKNESS AND SUPERIMPOSED THEREON AN ADHERENT LAYER OF GELATINE ABOUT 0.01 INCH IN THICKNESS THAT IS SENSITIZED TO BECOME INSOLUBLE IN WATER UPON EXPOSURE TO LIGHT, EXPOSING SELECTED AREAS OF SAID GELATINE LAYER TO LIGHT TO RENDER THE GELATINE IN THOSE AREAS INSOLUBLE IN WATER, DEVELOPING THE FACE OF THE EXPOSED PLATE STOCK WITH WARM WATER TO REMOVE GELATINE IN THE EXPOSED AREAS, WASHING THE FACE OF THE PLATE STOCK WITH AN ORGANIC SOLVENT CAPABLE OF DISSOLVING SAID THERMOPLASTIC MATERIAL WITHOUT SUBSTANTIAL SWELLING IN WHICH GELATINE IS INSOLUBLE TO REMOVE THE THERMOPLASTIC MATERIAL FROM PORTIONS OF THE LAYER THEREOF EXPOSED BY COMPLETE REMOVAL OF THE GELATINE COVERING SAID PORTIONS PROVIDING A RELIEF PRINTING PLATE HAVING A RELIEF PATTERN OF DEPTH GREATER THAN THE THICKNESS OF SAID GELATINE LAYER, DRYING THE COMPLETED PLATE, APPLYING PRINTING INK TO THE PATTERNED FACE OF THE PRINTING PLATE AND PRINTING WITH THE INKED PRINTING PLATE.

Claim 2

A METHOD OF RELIEF PRINTING WHICH COMPRISES PROVIDING A SENSITIZED PLATE STOCK FORMED OF A SHEET OF BASE MATERIAL HAVING FIXED THERETO A LAYER OF WATER-INSOLUBLE SYNTHETIC THERMOPLASTIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF POLYVINYL CHLORIDE, POLYSTYRENE AND CELLULOSE ACETATE ABOUT 0.01 INCH IN THICKNESS AND SUPERIMPOSED THEREON AN ADHERENT LAYER OF GELATINE ABOUT 0.01 INCH IN THICKNESS THAT IS SENSITIZED TO BECOME INSOLUBLE IN WATER UPON EXPOSURE TO LIGHT, EXPOSING SELECTED AREAS OF SAID GELATINE LAYER TO LIGHT TO RENDER THE GELATINE IN THOSE AREAS INSOLUBLE IN WATER, DEVELOPING THE FACE OF THE EXPOSED PLATE STOCK WITH WARM WATER TO REMOVE GELATINE IN THE EXPOSED AREAS, WASHING THE FACE OF THE PLATE STOCK WITH AN ORGANIC SOLVENT CAPABLE OF DISSOLVING SAID THERMOPLASTIC MATERIAL WITHOUT SUBSTANTIAL SWELLING IN WHICH GELATINE IS INSOLUBLE TO REMOVE THE THERMOPLASTIC MATERIAL FROM PORTIONS OF THE LAYER THEREOF EXPOSED BY COMPLETE REMOVAL OF THE GELATINE COVERING SAID PORTIONS PROVIDING A RELIEF PRINTING PLATE HAVING A RELIEF PATTERN OF DEPTH GREATER THAN THE THICKNESS OF SAID GELATINE LAYER, DRYING THE COMPLETED PLATE, APPLYING PRINTING INK TO THE PATTERNED FACE OF THE PRINTING PLATE AND PRINTING WITH THE INKED PRINTING PLATE.