| 摘要 |
PURPOSE:To obtain a coloring agent for pressure-sensitive papers, having excellent yellowing resistance, excellent weather proofness, and excellent NOx resistance, by using an alum, an alum multivalent metal salt or a mixture of a phenolic compound with these. CONSTITUTION:A coloring agent contains an alum or a multivalent metal salt of alum. The alum is a double salt of a compound of the formula M2SO4.M'2 (SO4)3.nH2O (where M is a monovalent metal or cationic compound, such as sodium, and M' is a trivalent metal, such as aluminum). By using a coloring agent composed primarily of an alum or a multivalent metal salt of alum, a pressure-sensitive paper having excellent chromogenic property when large numbers of papers are duplicated as well as excellent weather proofness and excellent NOx resistance in terms of paper and duplicated letters can be obtained. |
