Record materials comprising dyes (color former) which are colorless or substantially colorless in themselves but form colors upon contact with an acidic substance (color developer) have been extensively used for a pressure-sensitive copying paper, a heat-sensitive recording paper and the like. For the record materials, black color formers have been used mainly, but green color formers are sometimes used in combination therewith to adjust the hue of black colors. On that account, it is strongly desired that green color formers also exhibit excellent fastness before and after color formation. Further, the speedup of the services of communication recording devices such as facsimile requires increase in the color forming speed of the heat-sensitive recording papers used therefor. In this connection, there is a pressing need to improve color forming property of the green color formers used in admixture with the black color formers.
As green color formers, 3-diethylamino-5-methyl-7-dibenzylaminofluoran of the formula (referred to hereafter as "Compound A"), ##STR1## and 3-pyrrolidino-7-phenylaminofluoran of the formula (referred to hereafter as "Compound B"), ##STR2## have been disclosed respectively in Japanese Patent Publication No. 34044/1974 and Japanese Patent LOP Publication No. 9430/1975 or No. 82127/1975 and they have been put to practical use. However, these fluoran compounds are not satisfactory in respect of the fastness.
USPTO Backgrounds
USPTO Backgrounds