Heat-sensitive copying-paper

Claim 1

METHOD OF MAKING A HEAT-SENSITIVE COPYING-PAPER ADAPTED TO THE COPYING OF GRAPHIC SUBJECT-MATTER BY "FRONT-PRINTING" AS HEREIN DESCRIBED, AND COMPRISING COATING A TRANSPARENT INFRA-RED-TRANSMITTING CELLULOSIC SHEET MATERIAL WITH A DISPERSION OF PARTICLES OF A NORMALLY TRANSPARENT STABLE ORGANIC FUSIBLE SOLID IN A SOLUTION OF A TRANSPARENT FILM-FORMING BINDER IN A VOLATILE SOLVENT, REMOVING SAID SOLVENT, WITHOUT FUSING OR DISSOLVING SAID PARTICLES SO AS TO PROVIDE A NON-TRANSPARENT, INFRA-REDTRANSMITTING, HEAT-SENSITIVE LAYER, AND APPLYING A FURTHER COATING OF AN INFRA-RED-TRANSMITTING COLORING AGENT IN A BINDER SOLUTION, AND DRYING SAID FURTHER COATING, SO AS TO PROVIDE NON-TRANSPARENT, INFRA-RED-TRANSMITTING COLOR AND PROTECTIVE SURFACE LAYER; SAID FUSIBLE SOLID BEING FURTHER CHARACTERIZED BY MELTING TO A LIQUID WITHOUT APPRECIABLE VOLATILIZATION OR DECOMPOSITION AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 60-115*C., HAVING GOOD WETTING PROPERTIES TOWARD THE BINDER OF SAID HEAT-SENSITIVE COATING, AND HAVING SUBSTANTIALLY THE SAME REFRACTIVE INDEX AS THE BINDER OF SAID HEAT SENSITIVE COATING.