| 摘要 |
PURPOSE:To obtain sufficient color forming sensitivity and developed color density by using one or more kind of specific dihydroxybiphenyl as a coupler allowing a color forming substance to form a color at the time of heating. CONSTITUTION:In a thermal recording material consisting of a color forming substance, a coupler allowing the color forming substance to form a color at the time of heating and a binder, as the coupler, one or more kind of a compound selected from dihydroxybiphenyls represented by formulae I, II is used. As the compounds represented by the formulae I, II, 2,2'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 2,5-dihydroxybiphenyl, 2,3- dihydroxybiphenyl, and 3,4-dihydroxybiphenyl are designated. As the color forming substance, there are a triphenylmethane type, a triphenylmethanephthalide type, a fluoran type, a leuo auramine type and a spiropyrane type having a lactone ring, a lactam ring, a sultone ring and a spiropirane type. As the binder, polyvinyl alcohol, a polyvinyl alcohol derivative, water-soluble polyester and carboxy methyl cellulose are used. By this method, sufficient color forming sensitivity and developed color density are obtained even at low temp. and excellent high speed printability can be obtained. |
