International Paper Company

Dennis J Kerstanski

Anant D Mahale

Robert F Cassidy

Robert V Mahony

Narendra R Srivatsa

Richard R Wesolowski

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.

Multi-ply paperboard with improved stiffness

Method of making multi-ply paperboard sheet having layers of different

Deinking of impact and nonimpact printed paper is accomplished by repulping and defibering the printed paper in an alkali aqueous medium containing a deinking chemical to form an ink pulp medium. The presence of the deinking chemical causes separation of ink particles from the printed paper fibers. Removal of the ink particles from the ink pulp medium is accomplished by screening, flotation, forward cleaning, reverse cleaning, washing and mechanical dispersion procedures to produce a substantially ink free pulp medium. This substantially ink free pulp medium has a speck removal and brightness level sufficient to produce a high-grade recyclable grade paper product. The invention provides a deinking composition comprised of a mixture of one or more solvents, and nonionic and anionic surfactants, capable of high ink removal from all types of impact and nonimpact printed paper.

Deinking of impact and non-impact printed paper

Growing community of inventors

Warwick, NY, United States of America

Dennis J Kerstanski