Effect of Metal Ion Content in Dyebath on the Color of Wool Dyes

Abstract

The effect of metal ions in dyebath on the color of wool fabrics dyed with six kinds of common wool dyes was investigated. The dyes chosen were acid mordant dyes, Palatin dyes, Acidol dyes, Polar dyes, Lanasol dyes, and Lanaset dyes. The dyes were divided into 23, and fabrics were treated separately with these dyes according to the corresponding dyeing process. The metal ion of Cr6+, Cr3+, Cu2+, Fe3+, and Al3+was added separately into the dyebath, the content of which was 3 mg/L, 30 mg/L, and 300 mg/L. The differences in color between the fabrics dyed using the metal-contain-process and the metal-free-process were compared. The color difference is positively correlated with the metal ion content. When the metal ion content was 3 mg/L, the color difference values (ΔE) of most dyed fabrics were less than 1.7±0.3 of CIELAB. Moreover, color fastness was greater than 4, which means that the effect of the metal ions to color difference is acceptable. When the metal ion content was 300 mg/L, the ΔE values of most dyes were greater than 13.6±1.0 of CIELAB, which means that the metal ions have obvious effects on color difference. When the metal ion content was 30 mg/L, the ΔE values ranged from 1.7±0.313.6±1.0 of CIELAB. Based on the recommendation of theGB250-1995 Gray Scale for Assessing Change in Color(equivalent to the ISO 105/A02-1993 Textile-tests for Color Fastness-grey Scale for Assessing Change in Color), the ΔE value 1.7±0.3 of CIELAB and Grade 4 color fastness were used as the threshold to assess the results. When the metal ion content was 3 mg/L, Cu2+and Fe3+had low influence on the Palatin dyes, in which the color difference and the color fastness were less than the threshold. Meanwhile, Cu2+and Fe3+had excessive effects on the other kinds of dyes, with the ΔE values beyond the threshold. However, Cr3+had excessive influence on the Palatin dyes, with the color difference and the color fastness exceeding the threshold. In contrast, Cr3+had a smaller effect on the other kinds of dyes, with the ΔE values conforming to the threshold. Al3+had a significant effect on the acid mordant dyes, with the ΔE values beyond the threshold. In contrast, Al3+had a smaller effect on the other kinds of dyes, which were within the threshold. Cr6+had no significant effect on the kinds of dyes, in which the ΔE values did not exceed the threshold. When the metal ion content was 30 mg/L or 300 mg/L, we obtained mixed results. The color difference and color fastness values of kinds of dyes in the present study met the threshold, whereas some kinds of dyes were not within the threshold. The result has practical utility for setting the standards for water recycling in the wool dyeing industry.