EFFECT OF FIXING AGENTS ON THE AMOUNT OF WET END CHEMICALS ADSORBED ONTO A BLEACHED CHEMITHERMOMECHANICAL PULP

摘要

For a good performance, most wet end agents used in paper industry must adsorb onto pulp fibers. In this work, we studied the effect of four fixing agents, namely polyamine (PA), polydiallyldimethyl ammonium chloride (PDADMAC), polyethyleneimine (PEI) and a low-molecular-weight and highly cationic starch (LHCS), in promoting the adsorption of some typical wet end chemicals, specifically fluorescence whitening agent (FWA), methyl violet (MV) tinting dye, cationic starch dry strengthening agent (DSA-CS), poly(amidoamine)epichlorohydrin wet strengthening agent (PAE), and cationic polyacrylamide (CPAM) retention agent, onto a bleached chemithermomechanical pulp (BCTMP). It was found that the adsorptions of the wet end chemicals could be improved by all the four fixing agents. When the dosages of the fixing agents were based on the same weight, the LHCS was almost as effective as PA, PDADMAC and PEI, in improving the adsorptions of the negatively charged FWA, and the positively but weakly charged MV and DSA-CS, while it was slightly less effective in enhancing the adsorptions of the highly cationic additives, such as PAE and CPAM. When the dosages of the fixing agents were based on equal charges, the LHCS improved the adsorptions much more than the other three fixing agents. The fact that the LHCS tends to interact more with colloidal substances, while the other three fixing agents interact more with dissolved substances can be used to explain the phenomena discovered.