Heat sensitive copy sheet

Claim 1

A HEAT-SENSITIVE COPY SHEET PRODUCT CAPABLE OF PROVIDING HIGH CONTRAST DENSE BLACK IMAGES ON A WHITE BACKGROUND WHEN BRIEFLY HEATED AT IMAGE AREAS TO CONVERSION TEMPERATURE WITHIN THE APPROXIMATE RANGE OF 90-150*C., SAID PRODUCT CONTAINING, UNIFORMLY APPLIED OVER A PAPERLIKE CARRIER AND IN POSITION FOR HEAT-INDUCED INTER-REACTION, REACTANTS COMPRISING A SILVER SOAP OF AN ORGANIC ACID, A TONER FOR THE SILVER IMAGE, A DI-TERTIARYALKYL SUBSTITUTED PHENOL FIRST REDUCING AGENT FOR THE SILVER ION IN AN AMOUNT OF AT LEAST ABOUT 0.1 MOL PER MOL OF SILVER SOAP AND INSUFFICIENT TO FORM WITH SAID SILVER SOAP A DENSE IMAGE WHEN BRIEFLY HEATED THEREWITH, AND A PHOTOSENSITIVE DIFFERENT ACTIVE-HYDROGEN AROMATIC ORGANIC SECOND REDUCING AGENT FOR SAID SILVER ION IN AN AMOUNT NO GREATER THAN THAT OF SAID FIRST REDUCING AGENT, SAID FIRST REDUCING AGENT BEING FURTHER CHARACTERIZED AS FORMING WITH AN EQUAL WEIGHT OF SILVER BEHENATE AND ONE-FIFTH SAID WEIGHT OF PHTHALAZINONE A UNIFORMLY BLENDED TRACE DEPOSIT REQUIRING AT LEAST SIX SECONDS PREHEAT AT 100*C. BEFORE RAPIDLY DARKENING AT THAT TEMPERATURE, AND SAID SECOND REDUCING AGENT ON EXPOSURE TO ACITINIC RADIATION BEING RENDERED INCAPABLE OF REDUCING SILVER ION ON BRIEFLY HEATING WITH SILVER SOAP AT 150*C.