The structure of azo disperse dyes and its distribution on polyurethane fiber blend with polyester, or polyamide fiber

Using a range of monoazo disperse dyes, the distributions between PU fiber and polyester, and polyamide fibers were studied. It was found that at lower temperature, the disperse dyes exhausted more on polyurethane fiber than on polyester or polyamide, and then less exhausted as the temperature was increased. The distributions on polyurethane fiber blends varied with the structure of disperse dyes. The presence of halogen groups on diazo component at the ortho position to the azo link made dye uptake on polyurethane component higher, but the cyano derivative and the dye from diazo component of 5-nitro-benzothiazole tended to lower the adsorption on polyurethane fiber. The addition of two terminal cyano groups on coupling component showed lower dye uptake on polyurethane. The dyes with two terminal hydroxyl groups had high exhaustion on polyurethane fiber when blended with polyester fiber but low exhaustion when blended with polyamide.