Infrared low-temperature dyeing of wool using formic acid as auxiliary.

Two dyestuffs such as strong acid dyestuff yellow MR and weak acid dyestuff red NG were applied to dye wool fiber, and the exhaustion rate curves of traditional dyeing process and infrared dyeing process were compared. Infrared low-temperature dyeing process for wool fiber was carried out using formic acid as auxiliary. The effects of infrared dyeing temperature, infrared dyeing time and concentration of formic acid were discussed to optimize the dyeing process. The optimal infrared low-temperature dyeing processes were started at 50°C , and raised to 80°C or 90°C with a rate of 1°C /min, then kept for 50 minutes for strong acid dyestuff yellow MR and weak acid dyestuff red NG, respectively. The corresponding concentration of formic acid was 240 g/L or 260 g/L. After dyeing, the color water-fastness was grade 4 approximately. [ABSTRACT FROM AUTHOR]