NEW SIZING CHEMISTRIES AND MAJOR SIZING COMPONENTS

摘要

Within the last ten years alkyl ketene dimers (AKD) and alkenylsuccinic anhydrides (ASA) have increased rapidly their share in certain paper sizing markets due to increaced use of alkaline paper making technology in order to utilize advantages of calsium carbonate fillers (especially PCC). Nowadays ASA and AKD sizing is typically used in multipurpose office papers, which are uncoated fine papers, but require good printing properties, high brightness and high opacity. Depelopment of a new paper sizing chemical is a very complex process, because there are so many variables, which can influence the sizing efficiency. Optimization is needed at least on the following areas of paper making process; pulp, wire section, filler, white water, paper production conditions, additives , dosage point of size, filler and additives as well as making size emulsions (Scheme 1.) In addition new analytical- and test methods are needed to follow the process. In this paper mainly chemistries related to major sizing components is discussed. Paper is also focused mostly on ASA and AKD, their reactivity, structure property relationships and postulated sizing mechanisms.