The Preparation Of Dissolving Pulp Of Maple

In recent years, as people strengthing of environmental protection consciousness andadvocating green living,it is growing to demand more natural fiber that is raw material oftexltile fabrics. And viscose fiber has a natural biodegradable,people are better awareness ofthe viscose fiber. But emerging the contradiction of rice and cotton on soil,the strategy ofviscose fiber instead of cotton fiber has been an significant part for textile industry. Liquidamb-ar is studied as raw materials in this paper, including fiber morphology of Liquidambar,chemical composition,kraft pulping,mechanism of cooking,Dimenthyldioxirane bleaching andalkaline purification process.The main experimental results:1)Found through the fiber morphology and the main composition analysis:Liquidambaraverage fiber length and fiber length-width ratio are respectively14.6%and6.2%higher thantriploid MaoBaiYang; from the chemical composition, Liquidambar of Klason lignin matericalcontent are eight percent lower than Eucalyptus, but Liquidambar of holocelluse content are arethree percent higher than Eucalyptus. So the Maple woods are more suitable for chemical pulpthan the Eucalyptus.2) A three factor and four level orthogonal experiment was designed to study the effect ofalkali charge, sulfidity, cooking temperature and holding time on Liquidambar kraft pulping pr-ocess. It was found that the infulence on the pulp yield and kappa number of alkali charge isthe greatest and that of sulfidity is the least. The results also indicated that the optimal pulpingcondition is as follows: alkali charge17%(based on sodium oxide), sulfidity20%,cooking tem-perature165℃,holding time60min and liquor ratio1:6. The results of cooking is as follow:yeild49.87%,kappa number26.77,residual alkali3.44g/L etc. The results of adding anthraq-uinone into karft pulping process are as follow: yeild50.06%,kappa number24.11,residualalkali7.41g/L etc. So it btained good effect on the slectivity of deligninfication by adding anth-raquinone into Liquidambar kraft pulping process.3) The hot-water extraction of hemicellulose from Liquidambar chips before pulping wasstudied in this paper. The results are as follow: pH of the extraction liquor is3.61, solids contentis32.23g/L. Compared with no pre-hydrolysis chips, pentosan,Kalson lignin and hemicellulosecontents of pretreated chips reduce60%,7.1%and5%respectively; the ash content ofpre-hydrolysis chips is decreased down to0.11%.4) The pulping of preteated Liquidambar chips is lower alkaline charge. Comparing withthe pulp from untreated chips and under similar cooking conditions,10units Kappa numberlower and2units α-cellulose content higher are found for the pulpfrom preteated chips, but240ml/g viscosity of pulp lower and2%~3%decrease of yield are induced. 5) It inproves obviously bleaching effcetivesness that acetone is added into potassiumperoxymonosulfate bleaching process. Because both chemical mixture produce a new substancewhich is dimethyldioxirane(DMD). Adding small amount of DMD proved to be favorable to re-sidual lignin activating. It promoted the deliginficating rate and the deliginficating selectivitybefore Oxygen bleaching.6) The pertreated Oxygen bleached pulp(W-MO) and untreated Oxygen bleached pulp(U-MO) are treated by alkaline in the paper. Alkali concetration from6%to12%, the W-MOviscosity decreased10ml/g is found, while the U-MO viscosity decreased by72ml/g. To makethe pulp to achieve the same α-cellulose(95%), the W-MO pulp only8%alkali concentration isrequired, while the U-MO pulp required10%alkali concentration.7) The W-MOE pulp viscosity almost didn't change after hydrogen peroxide bleaching,while the U-MOE pulp viscosity has been on the decline. To make the pulp to achieve the samewhiteness(83%ISO), the W-MOE only2%hydrogen peroxide charge is required,while theU-MOE pulp required4%hydrogen peroxide charge.8)The pretreated Kraft pulp is treated by MOEP bleaching. The results are as follows: theα-cellulose content of dissovling pulp is98%; the whiteness of dissovling pulp is85.4%(ISO);the ash content of dissovling pulp is0.06%.