| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a black dye composition excellent in solubility, and solution stability. SOLUTION: This dye composition comprising a tetrazo-based black dye (C.I. Direct Black 19 or the like) is produced by reducing a nitro compound prepared by carrying out the diazo coupling of H-acid or its salt with nitroaniline and further conducting the diazo coupling of the produced amino compound with phenylenediamine. In the above method, (i) the nitroaniline in an amount of 0.8-1.9 mol based on 1 mol of the H-acid or its salt, (ii) the phenylenediamine in an amount of 0.5-1.9 mol based on 1 mol of the H-acid or its salt and (iii) a reducing agent in an amount of 2-8 mol based on 1 mol of the H-acid or its salt are used to thereby produce (A) a tetrazolium derivative or its salt, (B) a disazo derivative or its salt and (C) a trisazo derivative or its salt in free forms in (40/60) to (70/30) (weight ratio) of the components (A)/[(B)+(C)]. As a result, an aqueous solution comprising the black dye composition is stabilized.</p> |
