Lyocellfiber and method for preparation thereof

Fibrilleringstendensen to solvent-spun cellulose fiber can be increased by subjecting the fiber to treatment which reduces its degree of polymerization of about 200 units or more. Suitable treatments include strong bleaching, for example application of an aqueous liquor containing 0.1 to 10 wt% sodium hypochlorite (as tillgjengelig chlorine) to the fiber followed by steaming. Fiber can be treated in never-dried or pre-dried form. Fiber treated by the method of the invention is useful for example in the manufacture of paper and hydroflokede substances. Fiber of increased tendency to fibrillation can be ground to a Canadian Standard Freeness 400 in the decay test using 30.000 to 150,000 disintegrator revolutions and to a Canadian Standard Freeness 200 in the same test by 50,000-200,000 disintegrator revolutions.