In order to solve the problem of low quality and unstable source of dissolving pulp for domestic lyocell fiber,Russian spruce was used as raw material and high-quality dissolving pulp was prepared for lyocell fiber by pre-hydrolyzed sulfate cooking process.The effects of pre-hydrolysis,sulfate cooking,chlorine dioxide-hydrogen peroxide bleaching and acid treatment on the key technical indexes of dissolved pulp,such as α-cellulose content,polymerization,whiteness,ash content and metal ion content,were investigated.The experimental results show that the holding time of 90 min,the temperature of 150℃and the solid-liquid ratio of 1∶4 were the optimal prehydrolysis conditions,and the alkali content of 24%,the degree of vulcanization of 30%and the holding time of 180 min were the optimal cooking conditions.The slurry prepared under the optimal prehydrolysis and cooking conditions was treated with 1.5%chlorine dioxide bleaching,12%cold alkali extraction,5%hydrogen peroxide bleaching and 6%acetic acid,and the resulting pulp had a α-cellulose content,a whiteness of 85%,a polymerization degree of 647,an ash content of 0.06%,an iron ion content of 6 mg/kg,and a copper ion content of 3 mg/kg.Polarizing microscopy showed that the slurry could be completely dissolved in NMMO(moisture content of 13.3%)at 90℃for 30 s.
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