Treatment of Kraft Paperboards and a Kraft Pulp with Acrylonitrile

Résumé du livre

Acrylonitrile (CH 2 = CH -CN) was reacted with unbleached southern pine kraft linerboard and bleached southern pine kraft cardstock to determine the effect of this treatment on compressive strength and dimensional stability. A sweetgum kraft pulp was treated similarly before and after bleaching and the paper-making qualities, of the treated pulps were evaluated. The product qualities of these original materials changed considerably. The cardstock increased in weight by 30 percent after treatment with a 6 percent aqueous so1ution of acrylonitrile. However, the unbleached linerboard treated under the same conditions increased just slightly in weight The compressive strength of the unbleached liner-board increased 129 percent in the cross-machine direction at 90 percent relative humidity; under the same conditions the compressive strength of the bleached cardstock increased 122 percent. Dimensional stability of the cardstock increased 60 percent, but that of the unbleached linerboard was unchanged. The unbleached linerboard was, however, severely embrittled by the treatment. Bleached sweetgum kraft pulp treated with a 6 percent aqueous solution of acrylonitrile increased in weight by 135 percent. The unbleached sweetgum kraft pulp increased in weight by only 12 percent. The bonding capacity of the treated pulp fibers, and therefore the papermaking strength, was completely destroyed. The properties of opacity, scattering coefficient, refractive index, and moisture regain of the bleached kraft pulp were all decreased by the treatment.