Sustainable continuous process for cellulosic regenerated fibers

Textiles and hygiene products prepared from man-made fibres are essential for the welfare of humans. Majority of these fibres are, however, synthetic and thus have a role in global warming and micro plastic issue. This has created an opportunity to increase the production of cellulose-based man-made fibres, and consequently boosted the development of novel technologies in the field of cellulose dissolution and regeneration. One of the promising emerging methods to produce cellulosic fibres is the so called Biocelsol technology. It is based on the enzymatic activation of dissolving grade pulp, and on the dissolution of activated pulp into aqueous sodium zincate (ZnO/NaOH). The obtained dope is, after filtration, regenerated into cellulosic fibres by wet-spinning technique. A clear benefit of the Biocelsol-process compared to the widely used viscose process is the lack of carbon disulphide (CS2). The obtained fibres are white by nature and have exceptionally good adsorption capacity. The Biocelsol method was invented in the late 1980’s, when it appeared that the enzymatic treatment of cellulose increased its solubility into sodium hydroxide (Struszczyk et al 2001). The early day studies included comprehensive research with purified, specially designed and commercial enzyme preparations (Rahkamo et al 1996, Vehviläinen et al 1996), as well as dissolution of activated cellulose and regeneration it to various cellulosic shapes (Biocelsol 2007). The most efficient pre-treatment procedure proved to be separate mechanical and enzymatic stages in batch-mode with long residence times and moderate consistencies (Vehviläinen et al 2008). Dissolution of the enzyme-activated pulp was carried out in batch mode using a laboratory mixer at -5°C for 30- 60 min. The batch size was typically up to 1kg. The limited scalability of cellulose activation and dissolution stages has thus far hindered the commercialization of the technology. In this paper we describe the recent development in the Biocelsol technology that enable continuous operations to produce regenerated cellulosic fibres.