COPOLYMER COAGULANT IN THE PAPERMAKING PROCESS

摘要

An emulsion copolymer is used as a retention/drainage/formation aid in the papermaking process to improve dewatering, press solids and brightness. It is also used to treat coated broke where the white pitch or stickies and pigments are fixed to the long fibers and fiber fines. As a retention/drainage formation aid, the copolymer is a low molecular weight coagulant that is added to the papermaking cellulosic slurry prior to the first or after the last shearing stage, and, optionally, a flocculant may be added either before the addition of the copolymer or before the first or the last shearing stage. The copolymer ranges from 20 % to 50 %, preferably 40.0 % active in emulsion form and has a weight average molecular weight from 3 to 7 million. It is comprised of acrylamide (nonionic monomer) and diallyl dimethyl ammonium chloride (cationic monomer) in a weight percentage ratio range of from about 25:75 to about 75:25 based on the dry weight of the copolymer. The press solids ranges from 30 % to 65 % by dry weight solids and a Technidyne brightness level ranges from 50 to 95.