Studying On Light-weighed Offset Newsprint With Bamboo Chem-mechanical Pulp As Furnish

Pulping properties of CTMP and P-RC APMP of white powdery bamboo and mixed bamboos which abundantly covered in Guangxi was researched in this paper, and the mechanism of pulping was also researched and discussed.High compression can significantly improve the pretreatment effect in pulping process of bamboo CTMP and P-RC APMP. The dosage of sodium sulfite is the main factor to effect the brightness and physical strength of pulp, and the refining energy consumption can be significantly decreased after sodium sulfite treatment. Hydrogen peroxide bleaching efficiency of bamboo CTMP can be effectively raised by increasing the bleaching pulp consistency, and the reaction speed of bleaching can be accelerated by increasing the reaction temperature, but at the same time the invalid decomposition of hydrogen peroxide also can be accelerated. The utilization ratio of hydrogen peroxide can be improved by extending bleaching time. It is very important to adjust the suitable alkali-to-wood ratio in hydrogen peroxide bleaching, because the lower dosage of sodium hydrate can reduce the effect of bleaching, on the contrary the generation of color groups can be accelerated.The significant effect can be achieved by two stage chemical impregnation in pulping processing of bamboo P-RC APMP. Increasing the dosage of sodium hydrate can improve swelling of fibers, lower refining energy consumption, improve the effectof hydrogen peroxide bleaching and the bonding strength of fibers. But the excessive dosage of sodium hydrate can accelerate the invalid decomposition of hydrogen peroxide.The effect of hydrogen peroxide bleaching can be improved by high consistency retention. The hydrogen peroxide can participate in bleaching reaction sufficiently by prolonging reaction time and raising temperature, but the excessive time, temperature can reduce the brightness and opacity of pulp.Refining can improve the bonding properties of fibers, but also can oxidate some groups of fibers and generate many color groups in high temperature, reduce the brightness, so the refining parameter must be controlled.The chemical composition of pulp was studied and the results showed that the extractive of benzene-alcohol, lignin, hemi-cellulose and cellulose were dissolved in some levels by chemical impregnation. The study of pulp DR. showed that the bonds of lignin-ester were broken and the acetyls were get off, the hemi-cellulose was also dissolved in some levels, so bleaching reaction of hydrogen peroxide can break the conjugated carbonyl group, and improve the brightness in pulping process of CTMP and P-RCAPMP.The results of screen fractionation showed that the contents of fines & oversize in pulp of mixed bamboo were more than white powdery bamboo's in the same pulping technology process, it can prove that the cutting action of mixed bamboo are more than fandan bamboo in refining process. The average length of fibers in P-RC APMP are higher than CTMP, and fines are more less, bonding strength of fibers are more high. The swelling effects of fiberwalls can be taken place by a proper chemical impregnation, therefore the average fiber length of chem-mechanical pulp frombamboo can be protected during refining; the fibrillation effects on large proportion ofthe bamboo pulp fibers can be observed by means of a SEM.The bleached chem.-mechanical pulps from tested bamboo samples can be used as furnish for production of newsprint grades.