• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.31-38
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• 1999

Adsorption of polymeric flocculants and dry strength agents onto the surface of papermaking fibers is critical for their effective utilization since the polymeric substances not adsorbed on fibers or fines keep recirculating in the papermaking system to cause various operational difficulties and loss of raw materials. Problems associated with the unadsorbed polymeric substances generate great attention because unprecedent interests in utilization of recycled papers and papermaking system closure. In this study, to understand the effects of recycling on the adsorption propensity of cationic polyacryamide (PAM) dry strength resin onto hardwood bleached kraft pulp fibers and fines a systematic approach was followed. Never dried bleached hardwood kraft pulp was recycled in two different ways. In mode one recycling experiment never dried pulp was beaten then recycled three times by employing simple drying and disintegrating steps. In mode two recycling experiment beating of the recycled pulp was carried out after each recycling step. Adsorption of cationic PAM on fibers and fines was evaluated employing Kjeldahl nitrogen analysis method. The influence of recycling on water retention value, carboxyl content, sheet density and tensile strength of the pulp was examined. As the number of recycling increased, water retention value of the fiber was reduced due to hornification and this in turn caused a decrease in adsorption of cationic PAM. On the other hand, the carboxyl content of the recycled fibers increased because of the oxidation of fibers occurred during drying, and this caused an increase in adsorption of cationic PAM. Because of these two opposing factors the adsorption of the cationic PAM on the recycled fibers decreased and then increased slightly at third recycling step. Increase of PAM adsorption, however, did not provide did not provide and strength improvement for the recycled pulp fibers indicating greater influence of the honification on interfiber bonding.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.99-103
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• 2006

Use of recycled fibers in papermaking has been increased for economical and environmental reasons. Recycled panels are major liber resources for brown grades and newsprints. Since the recycled fibers have disadvantageous properties as raw materials for papermaking it is of great importance to optimize the use of these recycled fibers. OCC (Old Corrugated Containers) is the major fiber source for linerboards and corrugating mediums that require diverse specification in strength properties. Many studies have been focused to overcome the problems of strength reduction of brown grades when recycled fibers are used as raw materials. The problem of strength loss for papers made from recycled fibers is closely associated with the increased amount of fines in recycled fibers and hornification of fibers. Fines contained in the recycled fiber resources cause problems not only in paper properties but also in process runnability. This shows that the optimal management and proper use of fines in recycling papermaking system are critical to get most benefits of using recycled fibers. In this study some approaches for optimal use of fiber fines in recycled paper mill have been investigated. Stock samples, prepared in the laboratory and obtained from a recycling plant were used. Fractionation of these samples was made using Sweco screen. And the effect of the addition of polyelectrolytes including cationic PAM and PEI on drainage and retention was evaluated. Different methods of polymer addition were compared to find the most effective ways of treating recycled fiber stocks with polyelectrolytes. Addition of polyelectrolytes to the short fiber fraction was most effective in retention and drainage. The influence of the charge and molecular weight of these two polymers has been examined and discussed.