| As rapid development of domestic papermaking industries, and unceasing increase of production, the shortage of material and the environmental pollution had became the main issues of the impact of the development of domestic papermaking industry. According to the domestic and foreign situation of raw materials in papermaking industries, the thesis treated the pinus kesiya provided from the Yunjing paper and forest Co. as raw materials. The performance of diethanolamine pulping and papermaking using pinus kesiya was studied.The results indicated that the optimal diethanolamine pulping conditions as follows:solvent concentration70%, the highest temperature200℃, holding time5h, the solid-liquid ratio1:6, the assistant anthraquinone, and its dosage0.75%.After the optimal conditions were determined, cooking kinetics and cooking mechanisms have been studied in this thesis. The activation energies were obtained according to Arrhenius formula; and the mechanisms of delignification and carbohydrates degradation were concluded by measuring for lignin content and carbohydrate, and the defiberation point was determined according to rejects rate and yields of pulp. And, in order to study the change of lignin structure in the cooking process, the dissolving lignin structure and residue lignin structure were analyzed by Fourier transform infrared spectrum (IR),1H-NMR and13C-NMR. The results indicated that the diethanolamine of cooking pinus kesiya was reaction of Class I, activation energy of diethanolamine cooking of pinus kesiya was101.09KJ/mol.The delignification of diethanolamine cooking could be divided into3stages:(1)the initial delignification stage, which was from temperature rising to170℃, and its delignification rate was about30%;(2)the bulk delignification stage, which was from170℃to200℃for60min for the total delignification rate was close to90%;(3)the supplementary delignification stage, which was from60min at200℃to the end of cooking, and its delignification rate was97%above. According to rejects rate and yields of pulp, defiberation point during diethanolamine cooking was at200℃for30min, with the pulp yield of63.8%, rejects rate of2.3%.During the cooking process, a small amount of the (3-0-4in the lignin was ruptured, the Guaiacyl units were taken off largely. It was more beneficial to the replacement of the fifth carbon atom in the benzene ring at a high temperature for more than90min.Compared with the ECF and the TCF bleaching experiments, the results indicated that ECF bleaching ability is stronger than TCF bleaching ability. The pulp from diethanolamine cooking increase its brighteness a little slow than the pulp from KP cooking, its final brightness is83%ISO, and the viscosity is748.2mL·g-1, about150mL·g-1more than the KP under the same bleaching conditions.Beating characteristics of pinus kesiya bleaching pulp were studied by PFI mill. By the FQA fiber analyses, the fiber morphology of pinus kesiya bleaching pulp was measured, collaborated with optical microscope and scanning electron microscopy, the knowledge of beatability of pinus kesiya bleaching pulp could be more. No matter KP or diethanolamine pulp, the fiber length loosed a lot, fine fiber percent gained a lot, fibrillation was not obvious, when the beat degree was under40°SR, showed that the fiber-cutting down contribute to the fine fiber percent; but if the beat degree is over40°SR, the fibrillation became more and more as the degree increases. The beating degree could be adjusted according to the request of the characteristic of paper type, requested30°SR-60°SR beating degree usually.Make those bleached pulp into hand sheet, then, check its physical characteristics, the Basis weight60g/m2, tensile index and burst index have the same trend, rising till60°SR, then declined; the diethanolamine pulp perform better than the KP pulp. The tear index gained a little rise before30°SR, and then declined sharply; The tear index of diethanolamine is lower than that of KP pulp. |
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