Enzymatic treatment of wool pre-treated with cetyltrimethylammonium bromide to achieve machine washability

Abstract

Knitted wool fabric was pre-treated with cetyltrimethylammonium bromide in alkaline conditions in order to remove surface lipid to make the fibre more hydrophilic to enable more efficient subsequent treatment with the enzyme protease. As residual cetyltrimethylammonium bromide on the fibre surface causes an inhibitory effect towards protease, cetyltrimethylammonium bromide has to be removed from the wool. The efficacy of three different anionic surfactants in acid conditions was examined for removing residual cetyltrimethylammonium bromide from the treated wool. If the cetyltrimethylammonium bromide-treated knitted wool was washed with the anionic surfactant, Libraphos HC2A, in acidic conditions, followed by treatment with a chemically modified protease, machine-washable standards could be achieved. The possibility of whether native protease could be used instead of chemically modified protease in achieving shrink-resistance without excessive fibre damage was also studied, exploiting the tendency of residual cetyltrimethylammonium bromide to decrease the activity of the enzyme. It was found that if native protease or native protease in the presence of an enteric polymer was used to treat cetyltrimethylammonium bromide pre-treated wool, an improvement in shrink-resistance without excessive fibre degradation was observed. Machine washability could be achieved by optimizing the proportion of enteric polymer to native protease used to treat cetyltrimethylammonium bromide pre-treated wool. Up-scaling this process showed similar results. The dyeability of the wool with reactive dyes was unaffected by the treatment.

Keywords::

• wool
• protease
• hydrophilic
• lipid
• shrink resistance

Acknowledgements

We would like to thank the European Commission under the 6th Framework Programme for their funding of the project, Enzymatic Up-grading of Wool Fibres (032877-ENZUP). We would also like to thank the East Midlands Development Agency (EMDA) for providing further funding in the form of a Higher Education Innovation and Regional Fellowship (HIRF385).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.