| 摘要 |
PURPOSE:To improve printing density and to enhance tolerance to various chemicals, oil and water, sticking resistance and blocking resistance, by laminating a protective layer based on a specific polyvinyl alcohol resin to the surface of a thermal color forming layer. CONSTITUTION:A protective layer containing polyvinyl alcohol with a saponification degree of 86% or more is provided to the surface of a thermal color forming layer containing a colorless - light-colored dye precursor and a compound forming a color upon the reaction with dye precursor. The polymerization degree of polyvinyl alcohol is not especially limited but pref. 1,000 or more. Further, in order to enhance the water resistance of polyvinyl alcohol and to obtain the stability of a coating solution, for example, said polyvinyl alcohol is pref. used along with a water resistance imparting agent of a dialdehyde system. As the dye precursor, a triarylmethane compound, a diphenylmethane compound, a xanthene compound, a thiazine compound, a spiropyrane compound and a diazo compound etc. are designated. |
