Use of Cationic Starches in Systems Containing High Levels of 'Anionic Trash', 1993 Papermakers Conference Proceedings

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The use of cationic wet-end starch in systems containing mainly high yield pulps or (deinked) waste is often hampered by the presence of anionic trash materials present in the case of closed circuits.

Due to its low cationic charge- density. starch is not effective as anionic trash catcher even at substitutive levels for above what is commercially available today.

A good synergetic activity could however be found in laboratory experiments between synethetic polymers of the p-DADMAC, Polyethylene type and cationic starch. This was confirmed in lab sheet forming trials with recycling of the water.

The hypothesis that the synthetic anionic trash catchers ‘sweep’ the system and prevent the cationic starch being ‘neutralized’ by the trash was finally proven in a newsprint factory where strength improvements could not be achieved by starch a combination of synthetic and natural polymer solved the problem. A reduction of dewatering could be overcome by additional chemical dosage.