Prepartion Of Viscostic Pulp From Bleached Softwood Pulp

Currently, the raw material used for producing highest qualityviscose pulp is cotton linter. But, cotton linter resourse islimited forviscose pulp in our country, and with the rising costs of corporate profitmargins have been greatly compressed, the viscose pulp supply morenervous. So, developing a new material is significantly important toease up the source material providing.Coniferous wood is a main nativegrown tree in the southern of china and one of the important rawmaterials used for pulp-making. By it virtue of high level cellulose andlong fiber， coniferous wood is qualified as raw material appiled forproducing cellulose pulp.Softwood pulp board was used to prepare viscose pulp， cellulosepulp was made with three kinds of different processes. Themethylcellulose content and the polymerization degree of cellulose areimportant index of the pulp quality. Pre-treatment softwood pulp usingacid、 xylanase and liquid hot water was used, and the factors ofdifferent pre-treatment methods was studied upon the methylcellulosecontent and the polymerization degree of pulp. Furthermore, accordingto the pre-treatment results, the main conditions of sodium hypochloriteoxidation and alkali extraction were optimized.First, softwood pulp board was used to prepare viscose pulp bythree procedures， acid pre-hydrolysis, sodium hypochlorite oxidationand alkali extraction， the quality of viscose fiber can meet theutilization requirement for rubberized fiber.. It was carried out toinvestigated the effects of main factors, such as temperature, reactiontime, chlorine loading and alkaline loading on the methylcellulosecontent and the polymerization degree of pulp. The optimum parameterswas identified and the first technolgoy to prepare viscose pulp was obtained. At the first stage, the pulp was pretreated by dilute sulfate(concentration4.0%) under90℃for2h, the methylcellulose content andthe polymerization degree of pulp were85.31%and702, respectively.At the second stage, the pretreated pulp was oxidized by sodiumhypochlorite. Under the optimized conditions， chlorine loading1.0%,treating temperature40℃,treating time1.5h, the methylcellulosecontent and the polymerization degree were91.96%and504,respectively. At the three stage, the pulp was treated by sodiumhydroxide. The optimized conditions for producing the pulp were asfollow: alkali loading13%, treating temperature20℃, treating time1h.After these procedures, the methylcellulose content and polymerizationdegree were95.86%and522, respectively.Second, softwood pulp was used to prepare viscose pulp by threeprocedures， xylanase treatment, sodium hypochlorite oxidation andalkali extraction. The quality of cellulose fiber can meet the utilizationrequirement for rubberized fiber.It was carried out to study the effectsof main factors, such as temperature, reaction time, pH, xylanaseloading and chlorine loading on the methylcellulose content and thepolymerization degree of pulp. The optimum parameters was identifiedand the second technology to prepare viscose pulp was obtained. At thefirstl stage, the pulp was pretreated by xylanase60IU/g under50℃for1h, pH7.5, and the methylcellulose content and the polymerizationdegree of pulp were89.73%and922, respectively. At the secondl stage,the pretreated pulp was oxidized by sodium hypochlorite. Under theoptimized conditions， chlorine loading3.5%, treating temperature60℃, treating time2h, the methylcellulose content and the polymerizationdegree were95.67%and505, respectively. At the final stage, the pulpwas treated by sodium hydroxide. The conditions were as follow: alkaliloading13%, treating time1h, treating temperature20℃. After theseprocedures, the methylcellulose content and polymerization degree were95.78%and523, respectively.Third, softwood pulp board was used to prepare viscose pulp bythree procedures， liquid hot water, sodium hypochlorite oxidation and alkali extraction. The quality of cellulose fiber can meet the utilizationrequirement for rubberized fiber.It was carried out to discussed theeffects of main factors, such as temperature, reaction time,concentration and chlorine loading on the methylcellulose content andthe polymerization degree of pulp. The optimum parameters wereidentified and the third technology to prepare viscose pulp was obtained.At the first stage, the pulp was pretreated by liquid hot water. Under theoptimized conditions，concentration11.0%, treating temperature180℃,treating time40min, the methylcellulose content and the polymerizationdegree of pulp were88.84%and762, respectively. At the second stage,the preteated pulp was oxidized by sodium hypochlorite. Under theoptimized conditions， chlorine loading2.0%, treating temperature50℃, treating time1h, the methylcellulose content and the polymerizationdegree were91.73%and525, respectively. At the final stage, the pulpwas treated by sodium hydroxide（alkali loading13%） under20℃for1h. After these procedures, the methylcellulose content andpolymerization degree were95.85%and528, respectively.