Heat-sealable label stock

Claim 1

A HEAT-SEALABLE LABEL STOCK COMPRISING A BACKING SHEET HAVING ADHERENTLY BONDED TO ONE SURFACE THEREOF A DRY, SOLID COATING BY MEANS OF WHICH IT MAY, UPON HEAT ACTIVATION OF THE COATING, BE ADHESIVELY SECURED TO ANOTHER ARTICLE, THE COATING BEING NORMALLY DRY AND NON-TACKY AND INCLUDING A PLURALITY OF INDIVIDUALLY DISTINCT LAYERS SUPERPOSED ONE UPON THE OTHER, AT LEAST ONE OF SAID LAYERS CONSISTING ESSENTIALLY OF A SOLID THERMOPLASTIC RESINOUS MATERIAL AND ANOTHER OF SAID LAYERS CONSISTING ESSENTIALLY OF A SOLID PLASTICIZER FOR SAID MATERIAL, SAID MATERIAL AND SAID PLASTICIZER COEXISTING EACH IN PHYSICALLY INDEPENDENT LAYERS, BUT BEING ADHERENTLY BONDED TO EACH OTHER AND BEING ADAPTED TO BLEND ON HEATING, THE PLASTICIZER BEING PRESENT IN SIGNIFICANT AND SUFFICIENT PROPORTION TO MERGE UPON HEATING WITH SAID ADHESIVE MATERIAL TO PROVIDE A TACKY, ADHESIVE COATING WHICH AFTER SUBSEQUENT COOLING WILL HAVE AND RETAIN FOR A SUBSTANTIAL PERIOD OF TIME ADHESIVENESS PERMITTING ITS APPLICATION TO USE WITHOUT REHEATING, BUT WHICH FINALLY RETURNS TO A HARD AND NON-TACKY CONDITION.