The Preparation Of Dissolving Pulp Of Liriodendon Chinense-liriodendon Tulipifera By Water Pre-hydrolysis

With the increasing population, the declining arable land and cotton production, whilepeople’s awareness of environmental protection has enhanced, searching for a sustainable viscosefiber material to replace the unsustainable oil is necessary. Therefore, this research is about thepreparation of dissolving pulp based on hardwood Liriodendon chinense-Liriodendon tulipiferafor the production of viscose fiber. The main ideas of thesis are Liriodendonchinense-Liriodendon tulipifera fiber morphology, chemical composition, pre-hydrolysis process,kraft cooking and bleaching technology. The main process and experimental results are asfollows:(1) Liriodendon chinense-Liriodendon tulipiferas average fiber length of1.6mm, aspectratio of59.6, better than poplar; Liriodendon chinense-Liriodendon tulipifera holocellulosecontent82.7%, higher than poplar, and the lignin content of19.9%, amyl glycan content of15.1%, lower than poplar, Liriodendon chinense-Liriodendon tulipifera has good performance onpulping and papermaking, can be used in the preparation of dissolving pulp.(2) By researching the pre-hydrolysis process of Liriodendon chinense-Liriodendontulipifera, the optimum conditions for the pre-hydrolysis process: liquor ratio3:1, temperature170℃, P-factor700; Under this condition, the content of wood chips pentosan5.9%and thepentosan removal rate over60%.(3) The pre-hydrolysis precipitate was determined as lignin/LCC by IR spectroscopy.(4) After the pre-hydrolysis process, the kraft cooking conditions: alkali charge18%(basedon sodium oxide), sulfidity20%, liquor ratio3.5:1and H-factor1000, the experimental results:yield of pulp34.6%, kappa number10.5, pentosan content4.6%and brightness36.8%ISO; underthe same experimental condition, the conventional kraft cooking results: yield of pulp43.7%,kappa number21.6, pentosan content13.4%and brightness24.4%ISO, the kappa number andpentosan content can be decreased by the pre-hydrolysis process and the bleaching chemicals canbe saved with a high brightness pulp.(5) By researching the oxygen delignification of the pre-hydrolysis kraft pulp ofLiriodendon chinense-Liriodendon tulipifera with an L9(34) orthogonal test which was designedabout alkali charge, oxygen pressure, temperature and holding time, the result is that theinfluence of the alkali charge and temperature of oxygen delignification is higher, the oxygenpressure and holding time is lower. The suitable oxygen delignification process conditions in therange of selected technology level are as follows: alkali charge3%, oxygen pressure0.5MPa,temperature100℃, holding time60min, the amount of magnesium0.5%; The experimental results: yield of pulp94.9%, kappa number4.1, viscosity14.3mPa·s and brightness64.5%ISO.(6) During the same cooking process and oxygen delignification process conditions, theoxygen delignification results of kraft pulp: yield92.8%, kappa number11.4, viscosity21.7mPa·s and brightness55.3%ISO. The pre-hydrolysis kraft pulp has lower Kappa number, betterdelignification selectivity and higher brightness.(7) By OD1EpD2A bleaching, the pre-hydrolysis kraft pulp of Liriodendonchinense-Liriodendon tulipifera: α-cellulose96.7%, viscosity12.2mPa·s, brightness91.4%ISOand α-cellulose92.6%, viscosity9.4mPa·s, brightness84.4%ISO by OOpQPA bleaching, thedissolving pulp obtained the chemical hardwood pulp line with industry standards.