阅读说明：本技术 一种纤维素的溶解及其再生纤维素的制备方法 (Dissolving of cellulose and preparation method of regenerated cellulose ) 是由 余厚咏 王闯 于 2020-05-21 设计创作，主要内容包括：本发明提出了一种纤维素的溶解及其再生纤维素的制备方法,要点在于配制高浓度的无机盐溶液,在20～150℃的搅拌条件下加入0.5～18wt%的纤维素原料,纤维素逐渐溶解形成一定粘度的溶液纤维素溶液以不同方式挤出凝固,最终得到玻璃纸膜或者纤维。制备得到的玻璃纸膜或者纤维容易在制备过程中添加功能性材料,制备出高性能的复合再生纤维素材料。无机盐储量丰富,价格低廉,且对环境无污染,本发明符合“绿色发展”的理念,同时又极大程度上降低生产成本,因此本发明有着巨大的市场潜力。(The invention provides a method for dissolving cellulose and preparing regenerated cellulose thereof, which is characterized in that inorganic salt solution with high concentration is prepared, 0.5-18 wt% of cellulose raw material is added under the stirring condition of 20-150 ℃, the cellulose is gradually dissolved to form solution cellulose solution with certain viscosity, and the solution cellulose solution is extruded and solidified in different modes to finally obtain cellophane films or fibers. The prepared cellophane film or fiber is easy to add functional materials in the preparation process, and the high-performance composite regenerated cellulose material is prepared. The inorganic salt has rich reserves, low price and no pollution to the environment, and the invention conforms to the concept of green development and greatly reduces the production cost, thereby having great market potential.)

1. A method for dissolving cellulose, comprising the steps of:

1) preparing a high-concentration single or compound inorganic salt solution;

2) adding a certain amount of cellulose raw materials into the inorganic salt solution obtained in the step 1), and stirring and dissolving at a certain temperature to obtain a homogeneous cellulose solution.

2. The method according to claim 1, wherein the inorganic salt in step 1) is a metal salt, and the metal ions are each Li⁺、Mg²⁺、Al³⁺、Ca²⁺、Ti⁴⁺、Mn²⁺、Fe³⁺、Co²⁺、Cu²⁺、Zn²⁺The anion is one of Cl-and Br-.

3. The method for dissolving cellulose according to claim 1, wherein the concentration of the inorganic salt solution in the step 1) is inorganic salt: the molar ratio of water is 1: 10-1: 2.

4. The method for dissolving cellulose according to claim 1, wherein the cellulose raw material is added in an amount of 0.5 to 18wt% in the step 2).

5. The method for dissolving cellulose according to claim 1, wherein the stirring temperature in the step 2) is 20 to 150 ℃.

6. A method for producing regenerated cellulose suitable for the method for dissolving cellulose according to claim 1, comprising the steps of:

1) cooling the cellulose solution prepared in claim 1 to obtain a high strength and high toughness gel;

2) treating the gel obtained in the step 1) by a certain method, cooling and solidifying in a coagulating bath, washing to remove salt, and drying to obtain a regenerated cellulose product.

7. The method for preparing regenerated cellulose according to claim 6, wherein the gel in step 2) is processed by one of wet spinning and coating to form a film, so as to obtain regenerated cellulose products in both fiber and film forms.

8. The method of claim 6, wherein the coagulating bath in step 2) is one of an organic solvent, a mixture of an organic solvent and water, and a dilute acid solution.

Technical Field

The invention relates to a dissolving method of cellulose, in particular to a dissolving method of cellulose and a preparation method of regenerated cellulose thereof, belonging to the field of dissolving methods of cellulose.

Technical Field

Cellulose is an inexhaustible renewable resource in the nature, is one of the oldest and most abundant natural polymers on the earth, is mainly derived from plants such as wood, grass, bamboo, bast and seed hair, and has the advantages of short regeneration period, abundant and easily available reserves, environmental friendliness, good biocompatibility, low price, good biodegradability and the like. The efficient utilization of biomass resources is beneficial to relieving the problems of increasingly exhausted non-renewable resources such as petroleum and the like and increasingly severe environmental pollution in the world. However, cellulose is difficult to dissolve and infusible due to its high crystallinity and strong intramolecular and intermolecular hydrogen bonding, and is difficult to use as it is, and therefore, it is necessary to further treat it. Currently, the dissolution method of cellulose can be divided into two categories, wherein the derivatization method is to make some functional groups connected to the cellulose molecular chain through chemical reaction during the dissolution process, so that the cellulose molecular chain becomes soluble cellulose derivatives for dissolution, including sodium hydroxide/carbon disulfide (NaOH/CS)₂) Systems, carbamates, paraformaldehyde/dimethylsulfoxide (PF/DMSO), protonic acids, and the like; the direct dissolution method is realized by directly destroying hydrogen bonds among and in cellulose molecules through small solvent molecules, and comprises a cuprammonium solution, N-methylmorpholine-N-oxide (NMMO), lithium chloride/N, N-dimethylacetamide (LiCl/DMAc), an ionic liquid, an alkali/urea and NaOH/thiourea system and the like.

The efficient dissolution of cellulose depends on the continuous development of a solvent system, and the research and the utilization of a green efficient solvent system are hot spots of the development of cellulose. In patent publication No. CN 102432892A, urea/thiourea, polyethylene glycol and sodium hydroxide/sodium hydroxide aqueous solution are selected as dissolving solvent of cellulose, and uniform and stable solution with cellulose concentration up to 15 wt% can be prepared for natural cellulose with polymerization degree of 250.

The method adopts a high-concentration inorganic salt solution to dissolve the cellulose raw material to obtain 0.5-18 wt% of cellulose solution. The high-concentration inorganic salt solution is a good solvent for cellulose, the dissolving process is simple, the conditions are mild, the inorganic salt is cheap and easy to obtain, the inorganic salt is easy to recover, and the use process cannot cause environmental pollution. The cellulose solution can be used for preparing a series of regenerated cellulose products including gel, fiber and membrane by the processes of coagulation regeneration in a coagulation bath, washing for desalting, drying and the like. The addition of the functional material enables the regenerated cellulose composite fiber or the composite membrane to obtain high added value, and can meet the market demands of various fields.

Disclosure of Invention

The invention aims to provide a method for dissolving cellulose and preparing regenerated cellulose thereof, and regenerated cellulose fibers or films are prepared from a cellulose solution by wet spinning or coating to form films, and functional materials are added to prepare multifunctional regenerated cellulose composite materials, so that the performance is optimized to meet variable market demands.

The cellulose dissolving process has mild condition, the inorganic salt is cheap and easy to obtain and is easy to recover, and the use process does not cause environmental pollution.

A method for dissolving cellulose, comprising the steps of:

1) preparing a high-concentration single or compound inorganic salt solution;

2) adding a certain amount of cellulose raw materials into the inorganic salt solution obtained in the step 1), and stirring and dissolving at a certain temperature to obtain a homogeneous cellulose solution.

In the step 1), the inorganic salt is metal salt, and the metal ions are respectively Li⁺、Mg²⁺、Al³⁺、Ca²⁺、Ti⁴⁺、Mn²⁺、Fe³⁺、Co²⁺、Cu²⁺、Zn²⁺The anion is one of Cl-and Br-.

The concentration of the inorganic salt solution in the step 1) is inorganic salt: the molar ratio of water is 1: 10-1: 2.

The adding amount of the cellulose raw material in the step 2) is 0.5-18 wt%.

The stirring temperature in the step 2) is 20-150 ℃.

A method for preparing regenerated cellulose, which is suitable for the method for dissolving cellulose, is characterized by comprising the following steps:

1) cooling a cellulose solution prepared by a cellulose dissolving method to obtain high-strength and high-toughness gel;

2) treating the gel obtained in the step 1) by a certain method, cooling and solidifying in a coagulating bath, washing to remove salt, and drying to obtain a regenerated cellulose product.

The gel treatment method in the step 2) is one of wet spinning and coating film forming, and regenerated cellulose products in two forms of fibers and films are obtained.

The coagulating bath in the step 2) is one of an organic solvent, a mixed solution of the organic solvent and water and a dilute acid solution.

Furthermore, functional materials are added into the cellulose solution obtained by the cellulose dissolving method disclosed by the invention, or functional materials are added into the coagulating bath, so that high-performance multifunctional fibers can be prepared; the functional material can be antibacterial materials such as zinc oxide and the like, conductive polymer materials such as polyaniline and the like, high-strength conductive materials such as carbon nano tubes and the like, has rich and various sources, gives the regenerated cellulose composite fiber or the composite film extremely high added value, and is applied to various fields.

The inorganic salt solution used in the invention belongs to a non-derivative solvent of cellulose, the metal ions and the complex thereof directly act with cellulose molecules, the cellulose can be quickly and efficiently dissolved, the cellulose solution is semitransparent and can form gel after cooling, the cellulose gel obtained by dissolving the cellulose by the inorganic salt solution, the regenerated cellulose fiber and the regenerated cellulose membrane, especially the regenerated cellulose composite material added with functional materials, have multifunctional characteristics, can meet the performance requirements of different application fields, and have great market potential.

Microscopic change patterns of cellulose gradual dissolution were characterized using a microscope; x-ray diffraction (XRD) was used to characterize the crystallinity and the change of crystalline form of the obtained cellulose before and after dissolution. The results are as follows:

(1) microscopic change pattern of cellulose complete dissolution, see fig. 3;

(2) XRD patterns of regenerated cellulose membranes and cellulose feedstock, see figure 4.

The innovation points of the invention are as follows:

(1) the inorganic salt solution has mild conditions for dissolving cellulose raw materials, and the inorganic salt is cheap and easy to obtain and easy to recover, and does not cause environmental pollution in the using process;

(2) the novel process for preparing the regenerated cellulose material by dissolving cellulose with the solvent is simple and can be produced and applied in a large scale. Especially, the regenerated cellulose composite fiber and the composite membrane product have multifunctional characteristics, high added value and are suitable for various market demands.

Drawings

FIG. 1 is a schematic diagram of the dissolution of cellulose and the preparation process of regenerated cellulose.

FIG. 2 is a schematic representation of the dissolution of cellulose to form a homogeneous solution in example 1.

FIG. 3 is a microscopic change in the complete dissolution of cellulose in example 2.

FIG. 4 is an XRD pattern of the regenerated cellulose film and cellulose raw material of example 2.

Detailed description of the preferred embodiments

The invention is further illustrated below with reference to specific examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention. In addition, after reading the teaching of the present invention, those skilled in the art can make various changes or modifications to the invention, and these equivalents also fall within the scope of the claims appended to the present application.