| 摘要 |
PURPOSE:To obtain excellent thermal color developability, a sharp color image and excellent plasticizer resistance and a head matching property, by using specific dioxaheptane as a coupler and providing a specific coating layer onto a thermal color forming layer. CONSTITUTION:1,7-di(p-hydroxyphenylthio)-3,5-dioxaheptane is used as a coupler and a coating layer containing modified polyvinyl alcohol, glyoxal modified polyacrylic acid and an org. filler is provided onto a thermal color forming layer. The polymerization degree of polyacrylic acid is 1,000 or less and the amount to be used of glyoxal is generally 0.5-10pts.wt. of polyacrylic acid. As modified polyvinyl alcohol, carboxyl group modified polyvinyl alcohol is especially suitable. As the org. filler, a phenol resin, a urea-formalin resin, polycarbonate, a melamine resin, polystyrene or polypropylene are pref. adapted. |
