Strength Improvement of Kraft linerboard by Sweet Bamboo Pulp Substitution for long Fibers from Softwood Pulp

Abstract

Generally, linerboard is made from two-ply production. In the industrial linerboard production, a top layer paper is manufactured with a mixture of 55% unbleached eucalyptus pulp and 45% softwood pulp. This study substituted the long fibers of unbleached sweet bamboo pulp for the imported softwood pulp. Various proportions between the softwood pulp and the sweet bamboo pulp were 45:0, 30:15, 15:30 and 0:45, respectively.

The results showed the sweet bamboo pulp had slightly longer fibers (2.48 mm) than the softwood (2.39 mm). However, the runkel ratio of the sweet bamboo (0.97) was obviously higher than the softwood (0.64). Consequently, paper made from the sweet bamboo contained a higher tear index, but indicated a lower tensile index, than paper made from the softwood. The mixtures of softwood and sweet bamboo at ratio of 30:15 and 15:30 at all beating levels produced paper with a higher set of index (tension, tear, burst, and ring crush) and folding endurance than paper made from softwood solely (45:0). It indicated that adding the sweet bamboo pulp into the mixture between eucalyptus and softwood pulp will provide increased strength to the top ply of the linerboard when compared to using only eucalyptus and softwood. The sweet bamboo pulp can be used up to 60% to replace the softwood pulp or at proportions of 30:15 of softwood pulp to sweet bamboo pulp.