Study On The Anti-felting Finishing Of Wool Fabric With Multi-enzymes

Enzymes, as a biological catalyst can be produced by bacterial. With high efficiency andspecificity, mild reaction conditions and safety environmental protection, it has been widelyused in the textile industry. The outer layer of the wool scale is made of keratin, which iscomposed of very high content of cysteine.Using keratinase treatment instead of traditionalchlorination on wools, has been a new choice.In this study, according to that the scale of wool is composed of hydrophobic lipoid,highly cross-linked keratin and non-keratinized protein from external to internal, we usedcutinase from Thermobifida fusca, keratinase from Bacillus subtilis and Savinase16Lprotease to finish the wool fabrics. Based on individual and combined enzyme treatments, theoptimum finishing processes of different enzymatic treatments were obtained. Themodification effects of the enzymatic treatment of wool were investigated in terms of areashrinkage, textile strength, alkaline solubility, dyeing rate, K/S value and contact angle. UsingXPS, amino acid analysis and SEM, the mechanism of the enzymes was investigated.The finishing processes of the wool fabrics with keratinase alone and treated withkeratinase and cutinase were both optimized according to the standard W1of the WoolmarkInternational Wool Secretariat (IWS). After being treated with600U/g fabric keratinase aloneat pH8.0,50℃for36h, the shrinkage of the wool was5.77%, and the breaking strength was584N with a strength loss of7.35%. After being firstly treated with6U/g fabric cutinase atpH8.0,50℃for4h, then treated with400U/g fabric keratinase at pH8.0,50℃for24h, theshrinkage of the wool reached5.86, and the breaking strength was583N with a strength lossof7.46%. After being treated with6U/g fabric cutinase and400U/g fabric keratinase in onebath for18h, the shrinkage of the wool was5.52%, and the breaking strength was590Nwith a strength loss of6.65%.The wool fabric could obtain good anti-felting property after protease treatment, butserious damage would occur. In this paper, the wool fabrics were treated by protease with alargely decreased dosage of10U/g fabric and an extended time of8h. The results show thatthe treated wool reached machine-washable standard as well, meanwhile the strength loss wasdecreased obviously. Besides, when the protease was used together with keratinase, itshydrolysis efficiency was elevated. The same shrinkage was reached in just4h, and the treatedwool had a strength loss of merely7.3%.The wool treated with enzymes combination had better property than wool treated withkeratinase or protease alone. The wettability of wool treated with cutinase and keratinaseeither in one bath or in two baths both was improved dramatically. After the treatment withkeratinse and protease in two baths, the dyeing property of the wool improved remarkably andthe directional frictional factor decreased largely. However, the alkali solubility of the woolexceeded10%, showing a severe damage of the wool.The variation of the concentration of free thiol groups in the wool fibers showed that thedisulphide bonds of the wool could be cleaved by keratinase. SEM pictures showed that allkinds of treatments damaged to the scale of wool to some extent. The wool treated with keratinase and protease in two baths almost had smooth surface, which indicated that thistreatment had the greatest damage to wool. Amino acid analysis showed that the concentrationof the cystine declined after keratinase treatment, and oncentration of glutamic acid andtyrosine decreased obviously after treated with protease. XPS results showed that theconcentration of C-C(H) bond decreased remarkably after after treated with cutinase, and theconcentration of Cy-S-S-Cy declined, while the concentration of cysteic acid, which wasoxidation product of cystine, increased after treated with keratinase. No significant changes ofthese two elements were observed after treated with protease.