羊毛繊維の酸性クロム媒染挙動におよぼす重亜硫酸ナトリウム処理の影響

抄録

In order to clarify the validity of sodium bisulfite treatment in afterchrome mordanting process of wool fabric, we selected acid mordant dyes with the different molecular structures such as azo type (2 dyes), pyrazolone azo type (2 dyes) and triphenylmethane type (2 dyes) which are practically used. The relationship between color change or washing fastness and the added amount of potassium dichromate of the mordant-dyed fabrics treated by process with the presence or absence of sodium bisulfite was investigated. As a result, with respect to the dyes of the azo type and pyrazolone azo type, the color of the mordant-dyed fabric was not changed by the sodium bisulfite treatment. The effect of sodium bisulfite treatment was not observed also in the results of the washing fastness of the fabrics dyed with C.I. Mordant Red 19 which is a pyrazolone azo dye. In contrast, in the triphenylmethane dyes, obvious changes to the color of fabrics mordanted with the lower amount of potassium dichromate was observed if treated by sodium bisulfite. In addition, in the washing fastness results of these dyed fabrics, when the added amount of sodium dichromate was less than the amount of dye uptake, the influence of sodium bisulfite treatment was observed and the fastness was reduced. It was revealed from the above that in the triphenylmethane dye, the sodium bisulfite treatment acts to desorb the 1: 1 Dye-Cr (III) complex dye generated in the low chromium addition region. Furthermore, its action was presumed to be due to sulfate ions generated by reaction in which sodium bisulfite reduces Cr (VI) present in the fiber to Cr (III). However, it also found, in the case of adding a certain amount or more of potassium dichromate to the amount of dye uptake, that it is hard to be affected by the action of sodium bisulfite if Cr (III) coordinated with the dye was coordinated to the fiber constituent protein side chain.