Preparation method of cellulose casein composite fibers

Abstract

The invention discloses a preparation method of cellulose casein composite fibers. The method comprises the following steps: (a) dissolving casein and cellulose into an aqueous solution of ionic liquid to prepare a homogeneous phase mixed spinning dope; (b) filtering the obtained spinning dope, spinning, solidifying, stretching, washing, bleaching, oiling, and drying to obtain the cellulose caseincomposite fibers; the ionic liquid is obtained by mixing 90-110 parts by mass of 1-butyl-3-methylimidazolium chloride with 5-15 parts by mass of bi-1,4-bis[1-(3-methylimidazole)]butyl dichloride and5-15 parts by mass of bi-1,4-bis[1-(3-methylimidazolyl)]butyl diperchlorate. The method realizes the industrial production of the composite filters prepared by co-dissolving and co-producing the casein and the cellulose, thus having a higher practical value.

Description

technical field [0001] The invention relates to a preparation method of a composite fiber, in particular to a preparation method of a cellulose-casein composite fiber. Background technique [0002] Cellulose is the most widely distributed and most abundant polysaccharide in nature, accounting for more than 50% of the carbon content in the plant kingdom, and is one of the most abundant natural organic substances in nature. Cellulose mainly comes from plants, such as cotton, wood, cotton linters, wheat straw, straw, reed, hemp, mulberry bark, etc. Among them, the cellulose content of cotton is close to 100%, which is the purest natural source of cellulose, while general wood Among them, cellulose accounts for 40-50%, and there are 10-30% hemicellulose and 20-30% lignin. As a degradable green biomaterial, natural fibers are gradually playing an increasingly important role due to their superior properties such as light weight, degradability, low cost, high modulus, and high str...

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Problems solved by technology

[0006] Studies have found that ionic liquids can directly dissolve cellulose and protein, for example: Chinese patent CN200510077288.3 discloses a method of using ionic liquid as a solvent to mix and dissolve animal hair and cellulose raw materials to prepare biological protein wool fibers; Chinese patent CN200810033113.6 discloses A method for preparing cellulose and silk protein composite fibers by mixing and dissolving cellulose and silk protein with ionic liquid as a solvent; Chinese patent CN201510313099.5 discloses a method for preparing keratin composite fibers by using ionic liquid as a solvent to dissolve keratin and cellulose; China Patent CN201610058920.8 discloses a method of dissolving silk fibroin and cellulose by using ionic liquid as a solvent to prepare composite fibers; this also provides a new method for preparing composite fibers of cellulose and casein. Liquid is the method for solvent mixing and dissolving protein and cellulose to prepare protein-modified cellulose fiber, and in embodiment 5 and embodiment 12 respectively disclose bovine casein and rice straw pulp, and bovine casein and hemp pulp preparation composite The method of fiber; although the above-mentioned method has realized the co-dissolution and symbiosis of protein and cellulose including casein, but in the above-mentioned patent, ionic liquid (alkyl quaternary ammonium salt, alkyl imidazolium salt, alkyl pyrrole salt, etc.) is used to dissolve For protein and cellulose, pure ionic liquids are used to dissolve protein and cellulose, so that the obtained spinning stock solution has high viscosity and poor spinnability. In the subsequent spinning process, the pressure resistance of the spinneret and the Drafting has a great influence, which is unfavorable for subsequent spinning; and, in the above method, it is inevitable to cause loss of the fibrous properties of the raw material, so that the performance of the obtained composite fiber is poor, for example: Chinese patent CN200710043567.7 The resulting protein-modified cellulose fiber filament or short filament has a monofilament fineness of 1.5 to 5.0 dtex and a strength of 2.0 to 6.2 cN / dtex. Among them, the composite fiber prepared from bovine casein modified rice straw pulp in Example 5 The monofilament fineness is 2.0dtex, and the strength is 4.6cN / dtex; the monofilament fineness of the composite fiber prepared from bovine casein modified hemp pulp in Example 12 is 2.8dtex, and the strength is 4.2cN / dtex; the above situation leads to At present, although the co-dissolution and symbiosis of proteins and fibers including casein can be realized, it is basically still in the laboratory stage, and the industrial scale cannot be realized, which seriously limits the application and development of composite fibers

In addition, in the above method, when the ionic liquid dissolves protein (including casein) and cellulose, the dissolution time is relatively long, usually 2 to 48 hours, even up to 120 hours, which also severely limits its industrial production; and the dissolution temperature Higher, usually around 100°C, even as high as 150°C, high energy consumption, not easy for industrial production, and at the same time, due to its special properties, casein is not resistant to high temperature, so it needs to be realized at a lower temperature Co-dissolution and symbiosis with cellulose, and the above-mentioned high temperature is obviously not conducive to the co-dissolution of casein and cellulose to prepare composite fibers

[0007] In addition, although the composite fiber prepared by combining casein with other fibers can modify the physical and chemical properties of the fiber, the higher the content of casein in the composite fiber, the higher the higher. For example, Ren Hailong et al. (Ren Hailong, Yu Jianyong, Gao Jing, different Feed Ratio Properties of Casein Modified Acrylonitrile Fiber; Textile Journal; June 2009, Volume 30, Issue 6, Pages 19-23) Modified acrylonitrile fiber with casein to obtain casein modified It is mentioned in the article that the introduction of an appropriate mass fraction of casein has improved the strength of the fiber, greatly improved its moisture absorption performance, and at the same time has good friction performance, making it more wearable; at the same time It is mentioned that "the total casein content in the composite fiber is less than the feed content, and the larger the feed ratio, the greater the mass loss of casein, because there is partial hydrolysis during the polymerization process, and there is a loss of free casein during the spinning process." As a result, the impurity content in the fiber also increases with the increase of the casein content, probably because the casein is more polar and is more likely to absorb impurities such as oil agents, thereby affecting the fiber composition”; in fact, although there is no Tests have proved that the content of casein in the cellulose-casein composite fiber cannot be high, but when bovine casein is compounded with straw pulp in Example 5 of Chinese patent CN200710043567.7, the mass fraction of bovine casein is 4%. Example 12 When bovine casein is compounded with hemp pulp, the mass fraction of bovine casein is 5%, while the highest content of casein in the cellulose casein composite fibers currently on the market is only 8%, which also proves from the side The content of casein in composite fiber should be kept low

[0008] To sum up, although casein and cellulose have shown a good development trend in terms of co-solution and symbiosis, there are still many deficiencies, which are still in the laboratory stage, and the content of casein in composite fibers is relatively low. The performance modification of composite fibers is limited, therefore, it is necessary to develop a new preparation method of cellulose-casein composite fibers to promote the industrial production of cellulose-protein composite fibers

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