Heat-sensitive elements for use in thermography

Claim 1

A COATED THERMOGRAPHIC ELEMENT COMPRISING A FLEXIBLE SUPPORTING SHEET AND COATED THEREON AN OUTER LAYER OF THERMOPLASTIC POLYMERIC RESIN IN HIGHLY CRYSTALLIZED STATE HAVING AN ORIGINAL FIRST ORDER TRANSITION TEMPERATURE IN THE RANGE FROM 50*-200*C. AND AT LEAST 50*C. ABOVE THE GLASS TRANSITION TEMPERATURE OF THE RESIN FILM, SAID RESIN FILM IN SAID ORIGINAL CRYSTALLIZED STATE BEING ESSENTIALLY NONTACKY AND NONVISCOUS AND ESSENTIALLY NONTRANSFERABLE BY PRESSURE AT TEMPERATURES BELOW SAID ORIGINAL FIRST ORDER TRANSITION TEMPERATURE, SAID RESIN FILM HAVING MELT VISCOSITY AT SAID ORIGINAL FIRST ORDER TRANSITION TEMPERATURE GREATER THAN 100 POISES AND HAVING THE PROPERTY OF REMAINING, FOR A PERIOD OF AT LEAST ONE MINUTE AFTER FIRST ORDER TRANSITION, IN A TRANSFERABLE STATE IN WHICH RESIN CAN BE TRANSFERRED FROM THE COATED LAYER BY PRESSURE AT A TRANSFER TEMPERATURE AT LEAST 15*C. BELOW SAID ORIGINAL FIRST ORDER TRANSITION TEMPERATURE, THE MELT VISCOSITY OF THE RESIN FILM IN SAID TRANSFERABLE STATE AT SAID TRANSFER TEMPERATURE BEING IN THE RANGE FROM 100 TO 50,000 POISES, THE THICKNESS OF SAID RESIN FILM BEING IN THE RANGE FROM ABOUT 0.05 TO ABOUT 0.3 GRAM PER SQUARE FOOT, SAID LAYER HAVING INCORPORATED THEREIN A COMPATIBLE COLORANT, SAID ENTIRE ELEMENT BEING NONABSORBTIVE OF INFRARED RADIATION TO THE EXTENT THAT LESS THAN 20 PERCENT OF INCIDENT RADIATION IN THE RANGE FROM 1.0 TO 1.5 MU IS ABSORBED BY THE ELEMENT, THE POLYMERIC THERMOPLASTIC RESIN OF SUCH LAYER BEING A MEMBER SELECTED FROM THE GROUP CONSISTING OF LINEAR CONDENSATION POLYESTERS OF ALIPHATIC AND CYCOALIPHATIC DIOLS WITH ALIPHATIC AND CYCLOALIPHATIC DICARBOXYLIC ACIDS HAVING MOLECULAR WEIGHTS CORRESPONDING TO INTRINSIC VISCOSITY IN THRE RANGE FROM ABOUT 0.25 TO ABOUT 0.70.