Abstract: A process for production of chemical fibrous pulp for making paper, paperboard and other fibrous products from herbaceous plants, such as kenaf. Pulp from the herbaceous plant is made by a process which involves densification of pieces of all or part of the plants; i.e., both the core and the stalk or just the core portion, into cubes or pellets having a density ranging from about 15 to about 70 lbs/ft3, preferably from about 25 to about 50 lbs/ft3, which are then chemically digested to produce a fibrous pulp. The densified cubes or pellets may be digested alone or together with conventional wood chips. A principal advantage of the invention is that the densified cubes or pellets exhibit significantly better yield and strength after treatment by conventional chemical pulping methods as compared with the undensified material, enabling more efficient and economical use of this material to supplement limited supplies of conventional hardwood and softwood pulp sources.

Abstract: Stiffness improvements for multi-ply paperboard laid from chemically pulped softwood and hardwood papermaking furnish are obtained by fiber fractionating the softwood pulp and repositioning the resulting fractions. Chemically pulped and preferably bleached softwood fiber "rejects" of a fractionation screen are redistributed into the outer plies of a three-ply, 300-350 g/m (approximately 195 #/3,000 ft.) basis weight paperboard. The fractionation "accepts" are repositioned to the center ply for a 12% to 15% increase in Taber stiffness. The short, "accept" fiber from the fractionation screen is mixed with chemically pulped hardwood fiber or modified mechanical pulp of either species for formation of the center ply on a multiformer paper machine.

Abstract: Stiffness improvements for multi-ply paperboard laid from chemically pulped softwood and hardwood papermaking furnish are obtained by fiber fractionating the softwood pulp and repositioning the resulting fractions. Chemically pulped and preferably bleached softwood fiber "rejects" of a fractionation screen are redistributed into the outer plies of a three-ply, 300-350 g/m (approximately 195 #/3,000 ft.) basis weight paperboard. The fractionation "accepts" are repositioned to the center ply for a 12% to 15% increase in Taber stiffness. The short, "accept" fiber from the fractionation screen is mixed with chemically pulped hardwood fiber or modified mechanical pulp of either species for formation of the center ply on a multiformer paper machine.