| abstract |
Chemical heat amplification is provided in thermal transfer printing, wherein some of the heat necessary for melting and transferring ink from a solid fusible layer in a ribbon to a re- ce<sup>i</sup>ving medium is provided by an exothermic reaction. This chemical reaction is due to an exothermic material that is located in the ink layer, or in another layer of the ink bearing ribbon. The exothermic reaction reduces the amount of the input power which must be applied either electrically or with electromagnetic waves. Examples of suitable exothermic materials are those which will provide heat within the operative temperature range of the ink, and include hydrazone derivatives which are substantially colorless, and have a molecular weight in the approximate range 150-650. The group consisting of substituted aryl sulfonyl hydrazones, mono hydrazones of acylic -diketones, aromatic disulfonyl and diacyl hydrazones, and mono hydrazones of cyclic -dicarbonyl heterocycles are usable exothermic materials. |