FIBER PROPERTIES AS CONTROL VARIABLES IN PAPERMAKING .2. STRENGTHENING INTERFIBER BONDS AND REDUCING GRAMMAGE

Fibre properties can be used as control variables in paper-making, the reby offering an opportunity to improve simultaneously both the optica l and strength properties of paper. This approach, presented in the pr evious article, is applied here to the problem of reducing the basis w eight of paper. Special emphasis is placed on the factors affecting fi bre bonding, Experimental results show that interfibre bonds can be st rengthened by the addition of dry strength chemicals and fines. The ef fect of these additions on paper properties, and the mechanisms by whi ch they function, are studied here. When the grammage of paper is redu ced, nearly all the paper properties, including those normalized by ba sis weight, deteriorate. The first property that limits grammage reduc tion in printing papers is bending stiffness and the second is opacity . Results indicate that, by adding strength additives and fines, the g rammage of fine paper could be appreciably reduced without a loss in b ending stiffness, opacity or tensile strength.