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A long fiber; B short fiber
A Low-M dissolving pulp; B Dissolved pulp after cold alkali extraction; C High-A dissolving pulp after xylanase treatment
Dissolving pulp is a high-purity purified pulp. It is a raw material for the production of cellulose derivatives and is mainly used for the production of viscose rayon, acetate fibers, carboxymethyl cellulose, nitrocellulose, cellophane and other products.
Although there are many cellulosic raw materials used to make the dissolving pulp, wood and cotton linters are mainly used in industrial production.
Crop straw is a kind of cellulose fiber raw material with abundant resources and low price. Its chemical composition and tissue structure are similar to wood, so it can replace wood to prepare dissolving pulp. However, crop stalks have not been effectively used at home and abroad. A cellulose raw material to produce dissolving pulp.
Under the support of the National "973" Plan (No.2011CB707401), "863" Plan (No.SS2012AA022502), and National Key Science and Technology Support Project (No.2011BAD22B02), the research team of the Research Institute of Engineering Engineer Chen Hongzhang broke through the conventions from the straw itself. Based on the characteristics, it was found that the high content of heterocells is the key to restricting the production of dissolving pulp from crop straws as a raw material; the concept of steam explosion-comb-separation, separation of long and short fibers, and separate conversion was proposed innovatively; at the same time, innovative concepts were invented. Dry mechanical combing equipment provides equipment guarantee for large-scale production.
The coupling of steam explosion technology and mechanical combing technology cleans and efficiently achieves the separation of long fibers and short fibers in crop straw, increasing the content of fiber cells in long fibers to 85%, close to that of fiber cells in coniferous wood raw materials. content.
After pulping the long fibers, through further cold alkali extraction and xylanase treatment techniques, the content of α-cellulose in the dissolving pulp reached 97.1%, the viscosity was as high as 23.96 mPa·s, and the quality was better than that of viscose fiber in China. The national standards for wood pulp for pulp and viscose fiber can satisfy the use of low-mastic dissolving pulp and high-mastic dissolving pulp.
The separated short fibers are easily digested and can be used to construct a sugar platform cost-effectively. The steam explosion-coupled mechanical combing technology invented by the research team of the Hongjun Zhang breakthroughs the bottleneck that restricts crop straw as an industrial raw material, and provides a new approach for the integrated refining of crop straw.
The results were published in the international journal Bioresource Technology (Bioresource Technology, 139 (2013):59-65).
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