| abstract |
A substantially colorless marking liquid, particularly for use in pressure-sensitive record material, comprising (a) a colorless chromogenic material, (b) a solvent for said chromogenic material and (c) an additive for controlling CB decline. The additive for controlling CB decline, i.e., controlling the capability of the CB sheet to produce an image of satisfactory intensity even after exposure of the CB coating to light, includes certain chromogenic materials such as Pyridyl Blue and phenol derivatives having a free reactive (ortho- or para-) position. The marking liquid helps to prevent CB decline in, for example, carbonless copy paper, a long-standing problem in the art. |