Pulping, Bleaching and Papermaking Potential of Flax Fibre and Shives, 1999 Pulping Conference Proceedings

Saffet Karakus & D. N. Roy

University of Toronto

Krishan Goel

Innovations Centre

Domtar Inc.

Flax ( Linum usitatissimum ) is grown in many parts of the world, mainly for the production of linen from the fiber and linseed oil from the seed. Different strains of flax are grown for fiber or oil, with the latter emphasized in the United States and Canada. In the present work, chemical composition, pulping, bleaching and papermaking characteristics of flax fibre and flax shives have been studied. Chemical analysis of flax fibre and flax shives indicates that flax fibre has higher holocellulose and lower lignin content than that of flax shives. The pulps of flax fibre and flax shives produced in the laboratory using M/K Systems digester with kraft, kraft-AQ and soda-AQ pulping systems at 20, 22, 24, and 26 (%) active alkali (as Na2O) charges. Sulfidity for kraft pulping was 25%. Liquor to fibre ratio was kept constant at 7:1. Flax pulps were bleached using DEPAP sequences. Bleaching results indicate that it was possible to obtain 80+ brightness. Handsheets of 60 g/m 2 were prepared and tested for physical properties of flax pulps. Also market flax pulp was tested for comparison.

Results show that soda-AQ is effective in pulping flax fibre and flax shives with AQ charge as low as 0.1%. The pulp yields from flax fibre and flax shives, using 24 % chemical charge, were 51.6 % (kappa number 14.5) and 45 % (Kappa number 17.2) respectively. The strength properties (except tearing strength) of lab produced pulp were comparable to pulp obtained from the market.