Photothermography, printing sheet and printing ink therefor

Claim 1

TH METHOD OF PRINTING ONTO PAPER WHICH COMPRISES (1) COATING ONTO A FLAT SUPPORT A UNIFORM LAYER OF INK WHICH ABSORBS HEAT PRODUCING RADIATION AND CONVERTS IT TO HEAT AND WHICH CONTAINS A COLORING MATERIAL AND A VEHICLE WHICH IS AN ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF BENZOPHENONE AND METHYL O-BENZOYLBENZOATE, SAID INK CONTAINGING NO MATERIAL OTHER THAN SAID VEHICLE MELTING WITHIN 20*C. OF THE MELTING POINT OF THE VEHICLE AND WHICH INK BOTH IN ITS SOLID STATE BELOW THE MELTING POINT AND ITS LIQUID STATE IMMEDIATELY ABOVE THE MELTING POINT IN STABLE AND DOES NOT ADVERSELY AFFECT PAPER, (2) BRINGING THE SUPPORT AND INK LAYER TO A UNIFORM TEMPERATUE BELOW AND WITHIN 20 DEGREES CENTRIGRADE OF THE MELTING POINT OF THE VEHICLE, (3) ILLUMINATING ALL AT ONE TIME AN AREA OF SAID LAYER WITH HEAT PRODUCING RADIATION BY PROJECTING SAID RADIATION ONTO SAID AREA THROUGH A NEGATIVE SHEET WHICH HAS RADIATION TRANSPARENT AND RADIATION OPAQUE AREAS, SAID RADIATION BEING OF SUFFICIENT INTENSITY AND PROJECTED FOR A SUFFICIENT TIME TO RAISE THE TEMPERATURE OF THE INK AT THE RADIATED AREAS ABOVE THE MELTING POINT WITHOUT MELTING THE INK AT THE NON-RADIATED AREAS, (4) ALLOWING THE MELTED AREAS OF INK TO FUSE TO A SHEET OF PAPER FORMING A POSITIVE PRINT TO A (5) PHYSICALLY REMOVING THE UNMELTED AREAS ONLY OF THE INK.