COMPOSITION FOR REVERSIBLE HEAT SENSITIVE RECORDING MEDIUM AND REVERSIBLE HEAT SENSITIVE RECORDING SHEET

PURPOSE:To obtain the composition of reversible heat sensitive recording medium, forming a fresh picture with a high density and leaving no remaining image at the time of elimination, by a method wherein color developing and tone reducing agent, having an average grain size lower than a specified value, is blended with leuco compound having an average grain size smaller than the same of the color developing and tone reducing agent. CONSTITUTION:A composition for reversible heat sensitive recording medium is obtained by mixing a color developing and tone reducing agent, having an average grain size of 10mum or less, leuco compound, having an average grain size smaller than the same of the color developing and tone reducing agent and a binder resin such as polyvinyl alcohol or the like. The composition is molten or dispersed into water, organic solvent or the like to prepare a coating while the coating is applied on a substrate such as synthetic paper, plastic film or the like, then, is dried to form a recording layer and obtain a reversible heat sensitive recording sheet. A preferable example of this color developing and tone reducing agent is 2-amino-benzoic acid, 3-aminosalicylic acid, nicotinic acid, picolinic acid or the like, which is provided with an average grain size smaller than 10mum. On the other hand, a preferable example of the leuco compound is crystal violet lactone or the like, having an average grain size smaller than the same of the color developing and tone reducing agent.