| 摘要 |
PURPOSE:To form a clear picture of high contrast and without color mixture by a very little thermal energy by using a water-insoluble or hardly-water-soluble urea derivative as a color-eliminating agent for a thermal layer whose color is developed at low temperature. CONSTITUTION:A color-eliminating agent of urea derivative has, as its main ingredients, a thermal color-developing agent constituted of colorless or light-colored leuco dye and a developer constituted of phenolic or acid material and is also formed of such water-insoluble or hardly-water-soluble urea derivative as phenylthiourea, benzoylurea, 1-acetyl-3-methylurea etc., as the color-eliminating agent, contained in a thermal layer whose color is developed at low temperature and which is formed from a binder of organic high molecular compound. The color-eliminating agent of urea derivative can also be used as the color-eliminating agent for a color-eliminating layer provided between low-temperature and high-temperature thermal color- development layers. As for the color-eliminating agent used in the low-temperature thermal color development layer, the agent that has 0.05-0.3pt.wt. against 1pt.wt. of the color-eliminating agent used for the color-eliminating layer is fitted. |
