抄録
Rosin soap and dispersed rosin size is dominantly used as sizing agent (resistance to penetration of aqueous solutions) in Japan. The conventional rosin-related sizes for acid papermaking do not work well under weakly acid or neutral conditions. Recently, the neural rosin size which is effectively used at the papermaking pH of above 7 is coming into wide use under alkaline conditions for office paper manufacturing, because it is superior to the conventional alkaline sizes (AKD and ASA) in respect to waxy deposits in papermaking systems, paper friction, electrophotographic printability and ink-jet printability. On the other hand, even in the acid papermaking systems, the pH values of paper stock have become close to 5.5-7 with increasing the use of recycled paper containing CaCO3 filler. A new rosin-based size, which has efficiently size performance and size retention under weakly acid papermaking conditions is also developed. Wet-end chemistry of alum at acid or near neutral is not clearly understood. However, sizing performance can be further enhanced with the use of not only alum but cationic promoter such as cationic starch or polyacryl amide. Moreover newly improved neutral rosin size is developed in order to reduce the dosage as conventional neutral sizes.
