| 摘要 |
PROBLEM TO BE SOLVED: To improve the printed image preserving property of a recording part and the heat resistant base color stability of a white paper part by a method wherein a urethane compound, obtained by reacting a diphenol compound with a di-isocyanate compound under a specified molar ratio, is employed. SOLUTION: An excessive di-phenol compound is resolved in a solvent, such as acetone, methyl ethyl ketone, pyridine or the like, then, a di-isocyanate compound is added to the solution so that a molar ratio to the di-phenol compound becomes 1.01-10.0 to 1.0 or preferably 1.01-5.0 to 1.0 and the mixture is mixed for several hours at a room temperature. Thereafter, the solvent of reacted solution is removed and obtained solid body is dried to obtain the urethane compound. The compound is improved in color developing characteristics or printed image preserving property and the heat resistant base color stability of white paper part, however, these phenomena are considered due to that a urethane structure is provided in molecules and the amount of phenolic portion in the compound is comparatively small. |
