Recording materials and their manufacture

Claim 1

AN ELECTROSENSITIVE AND HEAT-SENSITIVE RECORDING PAPER COMPRISING A SUBSTANTIALLY DRY IMPREGNATED AND COATED PAPER SHEET, AN ELECTROSENSITIVE AND HEAT-SENSITIVE COMPOSITION INTIMATELY AND SUBSTANTIALLY UNIFORMLY DISPERSED THROUGHOUT SAID SHEET, SAID COMPOSITION COMPRISING: AN ALKALI METAL ACID CARBONATE RESPONSIVE TO HEAT APPLIED TO THE SURFACE OF SAID SHEET TO RELEASE CARBON DIOXIDE AND TO FORM AN ALKALI METAL HYDROXIDE IN SAID SHEET, A PH INDICATOR TYPE DYE RESPONSIVE TO THE PRESENCE OF ALKALI TO UNDERGO A MARKED VISIBLE COLORE CHANGE, MOISTURE IN A SMALL AMOUNT BUT IN AN AMOUNT SUFFICIENT TO PROVIDE A SOLVENT PHASE FOR SAID ALKALI METAL HYDROXIDE AND SAID DYE TO FACILITATE REACTION THEREBETWEEN; AND AN ELECTRO-CONDUCTIVE BACKING LAYER COATING ONE SURFACE OF SAID SHEET, SAID ELECTRO-CONDUCTIVE BACKING LAYER COMPRISING A CONDUCTIVE BACKING MATERIAL SELECTED FROM THE GROUP CONSISTING OF CARBON AND METALS, SAID CONDUCTIVE BACKING MATERIAL BEING BONDED TO SAID SURFACE OF SAID PAPER SHEET; WHEREBY CONTACT OF A HEATED STYLUS AND CONTACT OF AN ELECTRICAL STYLUS WITH SAID SHEET AT SELECTABLE AREAS OF THE OTHER SURFACE OF SAID SHEET ARE EACH EFFECTIVE TO INITIATE A CHEMICAL REACTION BETWEEN SAID ALKALI METAL HYDROXIDE AND SAID DYE TO PRODUCE VISIBLE MARKS ON SAID SHEET IN SAID SELECTABLE AREAS OF SAID LAST MENTIONED SURFACE OF SAID SHEET.