Application of chitosan in the textile industry
Textiles can be coated with the biopolymer chitosan and thus made water-repellent by binding hydrophobic molecules.
In the past, enzymes and renewable raw materials played a minor role in textile processing. Although they have been used, for example, to size and desize textiles, only a small proportion of them are currently used in textile finishing – compared with the large number of petrochemical products and textile auxiliaries. The Hydrofichi resarch project not only demonstrates the great potential of the biopolymer chitosan for the efficient hydrophobisation of textiles, but also defines further promising areas of application for the polysaccharide in textile processes.
Chitosan can be isolated from fishery waste as well as from side streams of insect cultivation or explicitly from microorganisms. Chitosan is also already offered and partly used as a biobased and environmentally friendly sizing agent in the textile industry. Due to its chemical structure, the renewable biopolymer is well suited for derivatisation and coating.
Template for hydrophobicity
The specific functional groups of the chitosan molecule allow to optimally adapt the properties of the textile surfaces with regard to a maximum hydrophobic equipment. In the Hydrofichi project, we have tailored functionalization of the biopolymer chitosan for use as a hydrophobising agent. In laboratory tests, the textile fabrics coated by Fraunhofer IGB showed significant hydrophobicity after finishing. Chitosan was successfully integrated into the textile finishing processes and was partly essential as a template for hydrophobicity. In the course of our investigations, the chemical and biotechnological functionalisation of chitosan with a wide variety of biobased reactants was optimised. Enzymes were also used for the first time for hydrophobic finishing of the fabrics. They therefore represent a unique selling point in the hydrophobisation of textiles.
The evaluation of the finishes was carried out by means of standardised tests but also with specially designed test rigs and methods. Contact angle measurements with values of over 140° and water repellency confirmed the successful finishing.
The highly efficient and at the same time sustainable chitosan formulations developed in the project can replace fossil-based components for textile finishing. The biobased hydrophobic chitosan derivatives are not only used as tailor-made components for textiles, but can also be of interest for medical technology due to their antimicrobial and hydrophobic effect, for example in prostheses and implants or as coatings for plastics and metals.
More information on the website of the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB.
