Technique for preparing cotton pulp with high-degree of polymerization for cellulose ether

Abstract

The invention relates to a process for producing cellulose ether used high polymerised cotton pulp, in particular to a cotton pulp production process mainly used for manufacturing high-viscosity cellulose ethers products, such as carboxymethyl cellulose, hydroxypropyl methylcellulose, etc. by utilizing cotton linters as the raw materials. The process adopts low temperature cooking to prevent carcinogenic toxic substances such as dioxins, organic halides, etc. from being produced through adding chlorine dioxide, thereby having low toxicity, reducing the pollution to the environment, and producing the cotton pulp with high polymerization degree, uniform fiber length, less dust and high alphacellulose content. Besides, the COD discharge amount of the waste water in the practical production is low, and belongs to the low pollutant emission.

Description

Technical field [0001] The invention relates to a cotton pulp production process, in particular to a production process for using cotton linters as raw materials to produce a high degree of polymerization cotton pulp for cellulose ethers, and is mainly used for the production of high-viscosity carboxymethyl cellulose , Hydroxypropyl methyl cellulose and other cellulose ether products cotton pulp production process. Background technique [0002] High degree of polymerization cotton pulp is made of high-grade cotton linters. It is mainly used to make cellulose ether products such as ultra-high viscosity carboxymethyl cellulose and hydroxypropyl methyl cellulose. It is an urgently needed commodity in the international market. With the development of the petroleum industry, especially offshore oil exploration, and the needs of the construction industry, especially in the production of food, medicine and other industries, the quality index requirements of cotton pulp are not only high...

AI Technical Summary

Problems solved by technology

[0003] At present, when domestic cotton pulp enterprises produce high-polymerization cotton pulp, most of them use traditional technology to strengthen caustic soda cooking conditions, do not add cooking aids, high-temperature bleaching, and strengthen bleaching strength; the equipment is outdated, and the product polymerization degree Low, whiteness less than 80%, and high dust, low added value, can only produce low-grade, low-viscosity cellulose ether products, which cannot meet the needs of the international market, and in the existing process, it is useless before cooking The special dry impurity removal equipment-the impurity remover selects and removes impurities for the cotton linters, and only uses the cotton opener to do simple impurity removal. The black liquor produced during the cooking process has a high COD content, and the COD emission content is about 45000mg / l. The problem of polluting the environment. Difficult to manage

[0004] Chinese patent, the application number is: "2006100684849", the title of the disclosure is "a kind of cotton pulp with high polymerization degree and its preparation method", the production of high polymerization cotton pulp does not require fiber length and freeness, and the process Among them, the cooking temperature is 125-160°C. When the temperature reaches 160°C, it is a high temperature. In actual production, the cellulose macromolecular chain of cotton linters will be broken, and two or more short-chain cellulose molecules will be generated. The degree of polymerization will be reduced; and in the chlorination bleaching process, according to the PH value range of 9 to 12 according to the listed process conditions, in actual production, only sodium hypochlorite or chlorine can be used for bleaching, but dioxins and organic compounds will be produced in the bleaching reaction. Halides and other carcinogenic toxic substances, among which dioxin is highly toxic and is one of the most toxic chemical substances found so far. It has been listed as a human carcinogen by the International Research Center, so it is not suitable for use in food, medicine and other industries carboxymethyl cellulose ether