Establishing a resource-efficient one-step process for dyeing and hydrophobic finishing of wool with a hydraulic spray atomising system.

Abstract: The textile industry is a big environmental polluter, with one of the biggest concerns being water pollution and usage. This necessitates resource efficient methods for wet textile processes. To reduce the resources used during wet textile processing, a novel technology was researched in this thesis to dye and hydrophobic finish wool in a one-step process. Two different wool fabrics were exhaust dyed and pad finished as a conventional method to compare to dyeing and finishing in a two-step and one-step process with a hydraulic spray atomising system. In all three processes, acid and reactive dyes were used for dyeing and hyperbranched polymers, i.e. dendrimers, were used for hydrophobic finishing. To test the colour and hydrophobicity fastness, washing and abrasion tests were done on the samples of all three processes. It was found that there is a big colour difference between the conventional and hydraulic spray method, where the colour is less strong in the hydraulic spray method. This has to do with the difference in the dye fixation step, where in the conventional method, the dye fixation happens in an aqueous medium, and in the hydraulic spray this happens in a nonaqueous medium. The hydrophobicity is however significantly better in the samples finished in the hydraulic spray, as this is rather a surface treatment. The results in colour and contact angle between the two-step and one-step process did not significantly change, so it can be concluded that it is possible to combine dyeing and finishing in the hydraulic spray method. The colour and hydrophobic fastness to abrasion and washing is significantly worse for the samples of the hydraulic spray method compared to the conventional method. The hydraulic spray method can still be optimised to overcome problems with colour and fastness, however this is future work. The hydraulic spray method uses significantly less water, chemicals and energy in a two-step process, and even more in a one-step process. Therefore, it has the potential to reduce the use of water, chemicals and energy in wet textile processing, for all types of fibres, and thus strongly contribute to a more environmental conscious wet textile process.