Study On Pulping Of The Triploid Populus Tomentosa Carr. Waste-crotch Wood

To get rid of the "bottleneck" of pulp wood shortage, the pulp and paper industry in China is making great efforts on the construction of forestry-paper integration project. The triploid P. tomentosa carr. plantations are ever booming in Northern China and its trunk wood are mainly produced BCTMP in some mills. Some properties of NaOH-AQ pulping from triploid P. tomentosa carr. crotch wood were studied. The practicality using its bleaching pulps to instead of hardwood pulp to develop the offset paper was researched in this thesis work.Compared with the triploid P. tomentosa carr. trunk wood, the holocellulose content and Pentosan of the crotch wood are lower and the extratives,ash and lignin content of the crotch wood are higher. The results showed that the triploid P. tomentosa carr. crotch wood fiber is not better than the triploid P. tomentosa carr. trunk wood for pulping and papering. The average fiber length and the ratio of length to width of triploid P. tomentosa carr. crotch wood are relatively higher than Black Italian Polar crotch wood, so the triploid P. tomentosa can. crotch wood is superior to Black Italian Polar crotch wood for pulping and papermaking.The method of NaOH-AQ pulping was asked by the mill. According to the experiment, the optimal technology conditions are: alkali charge(by NaOH):21%, AQ:0.05%, liquor ratio: 1:4, maximum temperature: 165℃, time at maximum temperature: 3h. Under this pulping condition, it can be gained that the pulp of triploid P. tomentosa carr. crotch wood with permanganate number 20.9 and pulp yield 50.6%and the pulp of Black Italian Polar crotch wood with permanganate number 18.4 and pulp yield. 49.1%.The brightness of the triploid P. tomentosa carr. crotch pulp are above 75%ISO by CEH bleaching or CED bleaching. The brightness of Black Italian Polar crotch pulp are above 75%ISO by CEHP bleaching. After hypochlorite bleaching or OP bleaching, the crotch pulp cann't be used to make offset paper because the brightness is lower than 70%ISO.The triploid P. tomentosa carr. crotch pulp by CEH bleaching and the Black Italian Polar crotch pulp by CEHP bleaching are respectively used to instead of hardwood pulp matching offset with bleaching softwood pulp and straw pulp. The physical properties of the paper exceed A grade standard of offset paper in QB/T1211-1991.