Method of preparing duplicate plastic-backed printing plates

Claim 1

IN A METHOD OF MAKING DUPLICATE PLASTICBACKED PRINTING PLATES, THE STEPS COMPRISING PREPARING AN ELECTROTYPE METAL SHELL, APPLYING A LAMINATED BONDING MATERIAL TO THE BACK FACE OF THE SHELL BY FRST APPLYING A LAYER OF A THERMOSETTING ADHESIVE TO THE BACK FACE OF THE ELECTROTYPE SHELL, APPLYING A SECOND ADHESIVE LAYER THE FIRST ADHESIVE LAYER, SAID SECOND ADHESIVE LAYER COMPRISING A MIXTURE OF SAID THERMOSETTING ADHESIVE LAYER AND A THERMOPLASTIC ADHESIVE, APPLYING A THIRD ADHESIVE LAYER OVER SAID SECOND ADHESIVE LAYER, SAID THIRD ADHESIVE LAYER CONSISTING OF THE SAME THERMOPLASTIC ADHESIVE WHICH FORMS A PART OF SAID SECOND ADHESIVE LAYER, PREPARING A THERMOPLASTIC BACKING CONSISTING OF APLASTIC MATERIAL CONTAINING AN ASBESTOS FILLER IN AN AMOUNT SUCH THAT THE RESULTANT THERMOPLASTIC BACKING HAS A THERMAL COEFFICIENT OF EXPANSION APPROXIMATING THE THERMAL COEFFICIENT OF EXPANSION PANSION OF THE ELECTROTYPE SHELL, SUPERPOSING SAID THERMOPLASTIC BACKING ON SAID BACK FACE OF THE ELECTROTYPE SHELL IN CONTACT WITH SAID LAMINATED BONDING MATERIAL, HEATING THE COMPOSITE ASSEMBLY TO A TEMPERAURE SUFFICIENT TO SOFTEN PRESSURE ON PLASTIC BACKING, APPLYING SUFFICIENT PRESSURE ON THE COMPOSITE ASSEMBLY TO FORCE THE SOFTENED BONDING MATERIAL AND BACKING MATERIAL INTO THE DEPRESSIONS IN THE BACK FACE OF THE ELECTROTYPE SHELL, RELEASING THE PRESSURE, COOLING THE PLATE TO A TEMPERATURE AT WHICH THE THERMOPLASTIC BACKING BEGINS TO HARDEN AND FORM AN INTEGRAL PART OF THE COMPOSITE ASSEMBLY, AND THEN PRESSING THE COMPOSITE ASSEMBLY A SECOND TIME TO PRESS ALL PRINTING ELEMENTS ON THE FRONT FACE OF THE ELECTROTYPE SHELL INTO A COMMON PRINTING PLANE.