| 摘要 |
PURPOSE:To attain a uniform color forming layer having less repellency, by using as a binding agent a combination of a copolymer consisting of mono- or di-isobutylene and maleic anhydride and a copolymer consisting of polyacrylamide and hydroxypropyl acrylate. CONSTITUTION:A combination of a copolymer (A) consisting of isobutylene or diisobutylene and maleic anhydride and a copolymer (B) consisting of polyacrylamide and hydroxypropyl acrylate is used as a binding agent for a thermo- sensitive color forming layer which contains a leuco dye, an acid substance and a binding agent as main ingredients. A weight ratio of copolymer B to copolymer A is set within a range of 1:9-9:1. It is preferred that copolymer B has a molecular weight of 50,000-200,000 and the content of acrylamide in the copolymer is within 50-90mol%. Further, copolymer A is used in amount of 0.1-3.0 pts.wt. with respect to 1pt.wt. leuco dye. |
