New Polymer Technology for Improved Pressing Efficiency in Coated Free Sheet Papers, 2000 Papermakers Conference Proceedings

Kenneth Henderson, Christopher Lewis--Conventional high charge density, low molecular weight polymers have been used to improve dewatering and pressing efficiency in coated free sheet production. Application methods vary from machine; however, the use of a long chain high molecular weight polyacrylamide (cationic or anionic) is generally used in conjunction with such chemistries. These chemistries include modified polyethyleneimine, poly-DADMAC, polyamine (DMA-Epi), and polyamidoamine. Although in-line blending of these coagulants with cationic polyacrylamide has sometimes shown enhancement in press dewatering over split addition, the level of chemical necessary to achieve the desired performance is sometimes limited by the high charge density of the short chain polymer. Novel polymer technology has shown significant improvements in press dewatering over traditional high charge density, short chain coagulants, increasing production rates. This approach also enhances fines and ash retention without the loss of formation. Moreover, the fixation function of this chemistry is not compromised despite a moderate charge density. The propensity for over cationization is decreased, while sheet consolidation is improved.