| 摘要 |
PURPOSE:To contrive an improvement of color forming properties after a moistening treatment, by adding at least a predetermined amount of a specified organic sulfur compound to a coating liquid. CONSTITUTION:At the time of providing a coated layer comprising an iron (III) compound on a base of a recording sheet utilizing a color reaction through formation of a complex of a ligand compound and the iron (III) compound, an organic sulfur compound having an S-OH bond is incorporated into a coating liquid for forming the coated layer in an amount of at least 1mmol per 100g of the solid components of the coating liquid. As the iron (III) compound, an organic phosphorus compound is preferable in view of the light color and favorable color forming properties thereof, and a composite iron (III) salt thereof with at least one of a carboxylic acid, a thio-acid, a dithio-acid and the organic sulfur compound having the S-OH bond has a light color and favorable initial color forming properties. Though the effect of the above arrangement can be recognized when an ordinary acidic paper is used as the base, the effect is conspicuously displayed when a base with a surface pH of at least 6.0 is used. |
