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| Preparation of Dissolving Pulp by Steaming -Cold Alkali Treatment of Bleached Softwood Kraft Pulp |
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| DOI：10.11980/j.issn.0254-508X.2019.01.001 |
| Key Words:bleached softwood kraft pulp steaming cold alkali treatment dissolving pulp |
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| Abstract:Combination of steaming and cold alkali treatments （steaming-cold alkali treatment method） as a process for upgrading bleached softwood kraft pulp to dissolving pulp was studied and developed. During the steaming process， the effect of different steaming pressure， time under pressure and pulp consistency on the viscosity， alkali resistance （R10）， the yield of steamed pulp and pH value of waste liquor was discussed. During the cold alkali treatment process， the effect of alkali concentration， temperature， and treatment time on the viscosity， alkali resistance （R10）， pentosan content and the yield of the dissolving pulp was studied. The results indicated that steaming pressure was the key factor affecting the steaming result， then followed the time under pressure and the pulp consistency was the least important. On the other hand， NaOH concentration was the most important factor affecting the effect of cold alkali treatment， followed by temperature， and the influence of treatment time was minimal. Finally， the optimum conditions of steaming were as follows: the pulp consistency of 40%， the steaming pressure of 0.6 MPa， the time under pressure of 25 min. The optimum conditions of cold alkali treatment were as follows: the NaOH concentration of 12.5%， the temperature of 20～40℃， the treatment time of 1 h and the pulp consistency of 20%. The resulting pulp with high reactivity， the viscosity of 398 mL/g， the alkali resistance （R10）of 92.2%， the pentosan content of 3.87%， the brightness of 86.1%（ISO）. |
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