| 摘要 |
PURPOSE:To enhance color forming properties and stability of developed color images, by incorporating a specified compound into a recording material utilizing a coloring phenomenon upon contact of a colorless dye with an electron- acceptive compound. CONSTITUTION:A compound of formula I is incorporated in a recording material utilizing a color forming reaction upon contact of an electron-donative colorless dye with an electron-acceptive compound. In the formula, each of Ar1 and Ar2 is an aromatic ring which may have a substituent group, R is-SO-,-SO2-or- OCOO-, and each of X and Y is oxygen or sulfur. Of the compounds of formula I, preferred are up to 30C ones having a melting point of 50-190 deg.C. The color less dye is a triphenylmethane phthalide compound, a fluoran compound or the like. The electron-acceptive compound may be an inorganic or organic Lewis acid or Broensted acid. Where the recording material is used as a thermal recording paper, the compound of formula I, the electron-donative colorless dye and the electron acceptive compound are used in the state of being dispersed through grinding to a particle diameter of not more than 10 mum in a dispersant.
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