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Licensed Unlicensed Requires Authentication Published by De Gruyter July 1, 2008

Characterisation of fines from unbleached kraft pulps and their impact on sheet properties

Marie Bäckström, Marie-Claude Kolar and Myat Htun
From the journal


Fines are an essential component in the papermaking process because they have a profound influence on the behaviour of the wet web and on the mechanical properties of the final sheet. Primary fines are present in the pulp prior to refining, and secondary fines are produced during refining. In the present investigation, two commercially manufactured unbleached pulps with kappa numbers of 45 and 90 were studied in terms of how they responded to refining with respect to the quality of fibre and fines. Primary and secondary fines were collected and characterised and their impact on sheet strength was evaluated by addition of known amounts to a refined and decrilled pulp. All the measured paper strength properties improved when primary and secondary fines were added. The strength improvement was generally somewhat higher in the second case. The effect was more pronounced at a higher level of addition. We attribute the main strength improvements associated with fines to improved consolidation by the creation of capillary forces between the surfaces.

Corresponding author. STFI-Packforsk, Box 5604, 114 86 Stockholm, Sweden

Received: 2007-11-13
Accepted: 2008-3-7
Published Online: 2008-07-01
Published Online: 2008-07-01
Published in Print: 2008-09-01

©2008 by Walter de Gruyter Berlin New York

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