VTT Technical Research Centre of Finland and Aalto University transform in their joint project TeKiDe wood fibres and discarded cotton textiles into viscose-type fibre to be used as raw material for textile products. The project develops particularly the carbamate, BioCelSol, and Ioncell-F technologies that are more environmentally friendly and safer than the currently used production method of viscose, based on the use of carbon disulfide. An important part of the project includes to develop a recovery system that would enable closed water and chemical loops in the process.
A single piloting process includes several steps: collection of waste textiles; removal of mechanical parts, such as buttons and zippers; grinding of textiles; chemical pretreatment; cellulose modification such as carbamation, dissolution in sodium zincate; filtering of the solution; air removal; spinning; post-processing of the fibre such as bleaching and drying.
In the first trial, approximately 150 kg of cellulose carbamate fibre will be produced from recycled cotton using the carbamate technology owned by VTT. Dissolution of cellulose is enhanced by forming carbamate groups in cellulose chains with the help of urea. The cellulose carbamate thus formed dissolves in cold sodium zincate solution, which is regenerated into carbamate fibre by precipitating the solution in acid.
The Ioncell-F technology, developed in collaboration between the Aalto University and the University of Helsinki, is based on direct dissolution of cellulose. It uses the dry-jet wet spinning technique and the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate ( [DBNH][OAc]), and is an environmentally friendly alternative to the water-intensive cotton production. The technology uses dissolved pulp, paper grade pulp from the kraft pulping process, as well as waste paper and cardboard, or waste cotton. The scale-up and piloting will not be implemented as part of this project.
The BioCelSol technology, jointly owned by VTT and the Tampere University of Technology, enhances the dissolution of cellulose by mechanical and enzymatic treatments before dissolution in sodium zincate instead of using carbon disulphide. The trials using BioCelSol technology have not been confirmed yet.
The TeKiDe project began last autumn and will be completed by the end of 2018. It is funded by the Helsinki-Uusimaa Regional Council’s Structural Fund for Mainland Finland programme, the City of Espoo, VTT, and Aalto University. The test runs will be performed at VTT’s Bioruukki piloting centre in Espoo, where a piloting environment based on wet spinning technique has been built during spring.
- VTT Technical Research Centre of Finland Ltd., Espoo, Finland
- Aalto University, Espoo, Finland
- University of Helsinki, Finland
- Tampere University of Technology, Finland