| 摘要 |
PURPOSE:To contrive better gradation expression of image density, by a method wherein an acicular crystalline filler is incorporated in a transfer layer in a specified amount based on the amount of a leuco dye, which is present in a particulate state. CONSTITUTION:The thermal transfer medium comprises a transfer sheet having a transfer layer comprising a leuco dye and a receiving sheet having a receiving layer comprising a color developer for the dye. Acicular crystals of the filler incorporated in the transfer layer assumes a network structure with the major crystal axis thereof in parallel with the surface of a base, are firmly bound to the base, and hold the fine particles of the leuco dye in voids in the network structure. A leuco dye ink melted in thermal printing exudes from the network structure onto the surface of the receiving sheet, little by little. By controlling thermal energy, the color development quantity of a developed color image formed on the receiving sheet is varied, resulting in an image with excellent gradation property. The amount of the filler used is at least 0.5pts.wt. per 1pts.wt. of the dye. If the amount of the filler is excessively small, the force for holding the dye is weak, and gradated images can not be obtained. |
