The Preparation Of Dissolving Pulp Of Liriodendron Hybrids By Weak Acid Pre-hydrolyzed Kraft Pulping

With the world population growing, reducing arable land, reducing the production of cotton, as well as chemical fiber products deficiencies, another textile raw materials-viscose, research has gradually become a new hot spot. Viscose fiber in texture similar to cotton, the aspects of comfort, breathability, and environmental protection are better than synthetic materials. This article is based on Liriodendron hybrids as a raw material is prepared in line with dissolving pulp for viscose fiber, the raw material into extruded and non extruded groups. This paper studies the chemical composition of Liriodendron hybrids, weak acid pre-hydrolysis process, kraft pulping and bleaching processes. In this paper, the main conclusions are as follows:(1) Liriodendron Hybrids fiber material found its performance is superior to conventional hardwood, having prepared dissolving pulp potential.(2) Non extruded group of chips weak acid pre-hydrolysis optimum conditions: 0.5% acid concentration (relative to the oven-dry wood mass fraction), the highest temperature of 170?,90min holding time and Liquid ratio 1:3.5. In this case, yield of 76.6%, pentosan removal rate of 63.2%, holocellulose content of 62.2%, Klason lignin removal rate of 35.3%, ash content decreased 69.3%. The extruded group of chips weak acid pre-hydrolysis optimum conditions:0.5% acid concentration, the highest temperature of 170?,30min holding time and Liquid ratio 1:3.5. In this case, yield of 79.4%, pentosan removal rate of 60.3%, holocellulose content of 62.6%, Klason lignin removal rate of 33.7%, ash content decreased 71.0%.(3) Non extruded Liriodendron Hybrids raw X-ray diffraction (XRD) showed that after weak acid pre-hydrolysis of cellulose crystallinity grounds 52.4% to 59.4%, weak acid pre-hydrolysis process leads to cellulosic feedstock aggregation has undergone some changes.(4) Non extruded Liriodendron Hybrids wood kraft pulping optimum conditions for:90min at 165?, liquid ratio of 1:4, with active alkali charge19%(Na2O), sulfidity 20%. At this point, treated raw material yield of 40.8%, kappa number of 11.5, viscosity of 13.2 mPa·s, pentose content of 2.8%, residual alkali content 6.7g/L, brightness 34.3%ISO. The kraft pulping of extruded chips with low viscosity, unable to complete the subsequent bleaching experiment.(5) Compared to conventional kraft pulp, yield, kappa number, viscosity, pentosan content, residual alkali content and solids content of pre-hydrolysis kraft pulp were lower, brightness were higher. SEM shows that the surface of conventional kraft pulp is relatively smooth and intact. After the dilute acid pre hydrolysis, the fibers become loose, the fiber surface grooves become obvious, the pits are more, and some fibers become damaged.(6) Liriodendron Hybrids pre-hydrolysis kraft pulp delignification process at pulp concentration of 10%, oxygen pressure 0.6MPa, highest temperature of 95?, holding time 30min. Get the brightness of 52.5% ISO, viscosity of 11.7 mPa's, kappa number of 5.2 and lignin removal rate of 54.8% bleached pulp.(7) Three different bleaching processes of Liriodendron Hybrids pre-hydrolysis kraft pulp were carried out. After OD0EpD1A and D0EPD1ED2A bleaching processes, get dissolving pulp for first grade viscose fiber from hardwood; After D0EPD1D2A bleaching processes, get dissolving pulp for second grade viscose fiber from hardwood.