Novel process of cellulose fibres and bio-based binders for nonwovens

The objectives of the Biocelsol project were to understand the enzymatic action on the cellulose and its impact on the structure and processability of cellulose, to develop viable processes for fibres, films, casing coatings, beads and sponges as well as to demonstrate them. The effect of combined chemical, mechanical and enzymatic treatments to produce dissolving cellulose with high alkaline solubility and acceptable viscosity was studied. The pulp characteristics such as alkaline solubility, viscosity, DP, crystallinity, porosity, fibre characteristic and WRV were analysed. Knowledge of the factors affecting cellulose properties and enzymatic treatments was obtained. As a result of different pre-treatments and enzymatic treatment with experimental or commercial enzymes, cellulose with high solubility and good solution properties was prepared and scaled up with low yield loss in the enzymatic treatment. Procedure to prepare cellulose with high solubility and good solution properties in aqueous alkali was developed with low yield loss in the enzymatic treatment. The procedure includes pretreatment of dissolving type pulp and enzymatic treatment with commercial or experimental enzymes. The treated cellulose is dissolved to obtain solution containing 4-6.5% cellulose, 0-1.3% zinc oxide and 7.8% sodium hydroxide depending on the application. Processes for fibres, films, impregnated webs, fibrous casings, beads and sponges were developed utilising the enzymetreated pulp without any need of carbon disulphide or other organic solvent. The highest tenacity of fibres obtained at laboratory scale remained close to 2 cN/dtex, which was close to the reference viscose fibres typical for nonwoven applications. The fibres produced for application trials for yarns, woven fabrics and for hydroentangled nonwovens were running without major problems. The industrial scale dissolution trial to produce fibrous casings by coating and bonding of the special paper web with Biocelsol was running well, even though the solution parameters were not yet optimal. Beads were successfully prepared from Biocelsol solution and their characteristics turned out to be different and probably better than of the beads made from the viscose solution. In the coming future bio-based binders for nonwovens are developed utilizing the excellent film forming behavior of particles produced via the controlled precipitation of alkaline soluble cellulose. The research and development gaps of the Biocelsol project were identified to be the scaling up of the best pretreatment method, the high alkali to cellulose ratio of the solution, the low fibre tenacity and the lack of the pilot scale production of fibres for application trials. All these are considered and are the topics of the presently running projects. NMP-CT-2003-505567 Specific Targeted Research Project (STREP) Nanotechnology and nanosciences, knowledge based multifunctional materials, new production processes and devices (NMP) Biotechnological Process for Manufacturing Cellulosic Products with Added Value (BIOCELSOL).