| 摘要 |
PROBLEM TO BE SOLVED: To provide a thermal sheet with excellent dynamic and static thermal sensitivity and appropriate rigidity, pliability and strength and further, high handling efficiency, free from the formation of a color in the texture under pressure by making a support of a synthetic resin sheet with specific density. SOLUTION: This thermal sheet is composed of a thermally color forming layer formed on a support. The support is formed of a synthetic resin sheet with, for example, a density containing a cavity of 0.2-0.5g/cm<3> in the support itself. If the density is higher than 0.5g/cm<3> , the thermal sensitivity is lowered, and the tendency of color formation in the texture under pressure is increased. On the other hand, if the density is not higher than 0.2g/cm<3> , the strength of the support is low and it is difficult to form the thermally color forming layer by coating. The synthetic resin sheet containing a cavity in the support is obtained by a method for mixing a synthetic resin with a foaming material generating a gas by heat and generating foam by extrusion, or mixing the synthetic resin with a non-compatible material against this resin and stretch the synthetic resin sheet obtained by fusion and extrusion into a lengthwise and a crosswise direction. |
