Research On Property Improvement Technology Of Hardwood Dissolving Pulp

Dissolving pulp,one kind of chemical refining pulp that composed of high content cellulose,is extensively applied in various aspects.Recently,it is higher for high reactivity demand of dissolving pulp,substantially improved viscose fiber production,the dissolving pulping industry is flourishing,and the production capacity is rapidly expanding,respectively.However,the increasingly fierce competition of the market also contribute to major manufacturers continue to pursue high quality dissolving pulp,and constantly improve various properties and product competitiveness.This paper mainly using hardwood dissolving pulp as raw material,to explore and optimize the beating and enzyme treatment pretreatment processes,improve α-cellulose content and Fock reactivity,reducing the hemicellulose content.This has important implications for dissolving pulp to widen sources of raw materials,enhancing the quality of dissolving pulp and even developing the green production,consequently.First discussed the beating process,using PFI refining technology,with the increase of beating degrees,fiber average degree of polymerization decreased,curl index and kink index rose substantially trend and the average width is gradually increased,indicating the behavior of swelling and fibrillation,which is conducive to improve the paper strength.Beating will decrease the content of α-cellulose and the length of fiber,so we should be control the beating degree of 47°SR.PFI beating is dominated by refining,especially late,mainly fiber sub-wire broom and fibrillation,destroy the primary wall and the outer layer of secondary cell wall of fibers,is conducive to their full contact with the drug solution and the reaction.Moreover,beating is good to improve the reactivity of dissolving pulp,save the use of carbon disulfide,product the environment and reduce production costs.Xylanase treatment technology was used to improve the properties of hardwood dissolving pulp,including α-cellulose,alkaline solubility,and Fock reactivity.The effect of xylanase dosage and treatment time on those targets was paid more attention in this study.Results showed that final pulp with α-cellulose93.7%,degree of polymerization 680,pentosan 5.4%,S10 8.1%and S18 7.2%,Fock reactivity 70%,was obtained under the condition of xylanase dosage 10 IU·g-1 and treatment time 90 min.At the same time,the fiber length of treated fiber was negligibly affected based on FQA analysis.Also,fibrillation happened on the treated fiber surface.Overall,xylanase treatment technology acted as a promising approach to improve the dissolving pulp properties for its downstream utilization.Discussion cellulase dosage and treatment time on the hardwood effect of dissolving pulp reactivity,when cellulose enzyme as 12 IU·g-1 the processing time was 120 min,Fock reactivity was increased to 71.5%,continue to increase the dosage of enzyme or extend the treatment time,the reactivity improved not apparently.Moreover,the average degree of polymerization of 638,α-cellulose content of 86.5%,alkali solubility S10 and S18 are increase to 10.17% and 8.97%,compared with that of raw pulp.After cellulase treatment,some partial degradation of cellulose occurs,macromolecules strand breaks,decrease the content of α-cellulose and degree of polymerization.By SEM scanning electron micrscopy showed that after cellulase treatment,fiber becomes soft and loose,the surface becomes rough and flaking,exposing the original fine fibrils more of S2 layer,the specific surface area is increased pulp fibers,destroyed the close-knit structure of cellulose crystallinity region,which is conducive to fiber contact and the reaction with chemicals to improve reactivity of dissolving pulp.