阅读说明：本技术 一种壳聚糖纤维材料的制备方法 (Preparation method of chitosan fiber material ) 是由 蔡杰 钟奕 张俐娜 于 2019-02-01 设计创作，主要内容包括：本发明公开了一种壳聚糖纤维材料的制备方法。首先将壳聚糖加入到碳酸氢盐的水溶液,直接搅拌溶解壳聚糖；或者将壳聚糖用稀酸溶解后再用碱中和,无需分离,继续加入碳酸氢盐,搅拌溶解壳聚糖；将壳聚糖加入到碱液或碳酸盐的水溶液中,通入二氧化碳,生成碳酸氢盐来溶解壳聚糖；将甲壳素进行脱乙酰化生成壳聚糖,调整碱液浓度后,通入二氧化碳,生成碳酸氢盐来溶解壳聚糖。加入稳定剂有助于增强溶解能力。将溶解了壳聚糖的弱碱性水溶液喷丝进入凝固浴,得到壳聚糖纤维状凝胶,将该纤维凝胶进行牵伸取向或者不经过取向,干燥后得到壳聚糖纤维。本发明避免了壳聚糖在酸性或者强碱性条件下的降解,有利于保证壳聚糖溶液在材料加工过程中的稳定性。(The invention discloses a preparation method of a chitosan fiber material. Firstly, adding chitosan into a bicarbonate aqueous solution, and directly stirring to dissolve the chitosan; or dissolving chitosan with dilute acid, neutralizing with alkali, adding bicarbonate, and stirring to dissolve chitosan; adding chitosan into an aqueous solution of alkali liquor or carbonate, and introducing carbon dioxide to generate bicarbonate to dissolve the chitosan; deacetylating chitin to generate chitosan, adjusting the concentration of alkali liquor, and introducing carbon dioxide to generate bicarbonate to dissolve the chitosan. The addition of a stabilizer helps to enhance the dissolving capacity. And (3) spinning the alkalescent aqueous solution in which the chitosan is dissolved into a coagulating bath to obtain chitosan fibrous gel, carrying out drafting orientation or non-orientation on the fibrous gel, and drying to obtain the chitosan fiber. The invention avoids the degradation of chitosan under acidic or strong alkaline conditions, and is beneficial to ensuring the stability of chitosan solution in the material processing process.)

1. A preparation method of a chitosan fiber material is characterized by comprising the following steps:

(1) preparing a weakly alkaline aqueous solution, wherein the weakly alkaline aqueous solution consists of bicarbonate, a stabilizer and water; wherein the final concentration of bicarbonate is: 0.2 to 1.5 mol/kg^-1The final concentration of the stabilizer is 0.3-5.0 mol/kg^-1Urea or 0.3-1.2 mol/kg^-1Thiourea or a mixture of the two, and the balance water;

(2) preparing a chitosan weakly alkaline aqueous solution: adding chitosan into the alkalescent aqueous solution obtained in the step (1), continuously stirring for more than 30 minutes under the condition that the freezing point is 35 ℃, dissolving the chitosan, and defoaming to obtain a transparent chitosan solution;

(3) preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath; the coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%;

the bicarbonate is a single bicarbonate aqueous solution or a mixture of multiple bicarbonates aqueous solutions.

2. The method of claim 1 for preparing a chitosan fiber materialThe method is characterized in that the mass fraction of bicarbonate in the weak alkaline aqueous solution prepared in the step (1) is 0.3-1.2 mol/kg^-1The stabilizer is 1.0-4.0 mol/kg^-1Urea or 0.4-1.0 mol/kg^-1Thiourea and the balance water.

3. A preparation method of a chitosan fiber material is characterized by comprising the following steps:

(1) dissolving chitosan in a stabilizer at a concentration of 0.1-1.0 mol/kg^-1Adding a proper amount of alkali to the inorganic or organic acid aqueous solution to adjust the pH of the solution to be neutral, and separating out chitosan; the stabilizer is 0.3-5.0 mol/kg of final concentration^-1Urea or 0.3-1.2 mol/kg^-1Thiourea or a mixture of the two; the alkali for adjusting the pH of the solution is any one of alkali hydroxide, alkali metal carbonate, alkaline earth metal carbonate, alkali metal bicarbonate, alkaline earth metal bicarbonate, ammonia water, ammonium carbonate and ammonium bicarbonate or a mixture of the alkali hydroxide, the alkali metal carbonate, the alkaline earth metal bicarbonate and the ammonia water; the inorganic or organic acid is preferably acetic acid, hydrochloric acid, citric acid, etc.;

(2) adding bicarbonate into the mixture of chitosan and water in the step (1), continuously stirring for more than 10 minutes under the condition of the freezing point to 35 ℃, dissolving the chitosan, and defoaming to obtain a transparent chitosan solution; the final concentration of the bicarbonate is 0.2-1.5 mol/kg^-1；

(3) Preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath; the coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%;

the bicarbonate is a single bicarbonate aqueous solution or a mixture of multiple bicarbonates aqueous solutions.

4. The method for preparing chitosan fiber material according to claim 3, wherein the stabilizer added in step (1) has a final concentration ranging from 1.0 to 4.0 mol-kg^-1Urea or 0.4-1.0 mol/kg^-1Thiourea; the final concentration range of the bicarbonate in the step (2) is 0.3-1.2 mol/kg^-1。

5. A preparation method of a chitosan fiber material is characterized by comprising the following steps:

(1) preparing an alkaline aqueous solution, wherein the alkaline aqueous solution consists of alkaline hydroxide or carbonate, a stabilizing agent and water; wherein the final concentration of the alkali hydroxide is 0.2 to 1.5 mol/kg^-1The final concentration of carbonate is 0.10 to 0.75 mol/kg^-1The final concentration of the stabilizer is 0.3-5.0 mol/kg^-1Urea or 0.3-1.2 mol/kg^-1Thiourea or a mixture of the thiourea and the water;

(2) adding chitosan into the alkaline aqueous solution obtained in the step (1), introducing carbon dioxide, continuously stirring for more than 30 minutes under the condition that the freezing point is 35 ℃, dissolving the chitosan when the pH value of the solution is about 7-10, and defoaming to obtain a transparent chitosan solution;

(3) preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath; the coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%;

the alkaline hydroxide is metal hydroxide, ammonium hydroxide, quaternary ammonium base, preferably sodium hydroxide, potassium hydroxide, ammonium hydroxide or a mixture thereof; the carbonate is preferably sodium carbonate, potassium carbonate, ammonium carbonate, or a mixture thereof.

6. The method for preparing chitosan fiber material of claim 5, wherein the final concentration of hydroxide in the alkaline aqueous solution prepared in step (1) is 0.3-1.2 mol-kg^-1The final concentration of carbonate is 0.15-0.6 mol/kg^-1The final concentration range of the stabilizer is preferably 1.0-4.0 mol/kg^-1Urea or 0.4-1.0 mol/kg^-1Thiourea and the balance water.

7. A preparation method of a chitosan fiber material is characterized by comprising the following steps:

(1) chitin and the mass molar concentration of 8.0-12.5 mol/kg^-1Mixing sodium hydroxide aqueous solution or potassium hydroxide aqueous solution, heating to perform deacetylation reaction to generate chitosan;

(2) adjusting the final concentration of sodium hydroxide or potassium hydroxide in the mixture obtained in (1) to 0.2-1.5 mol/kg^-1Reducing the temperature of the mixture to between the freezing point and 35 ℃, adding a stabilizer, introducing carbon dioxide at room temperature, converting sodium hydroxide or potassium hydroxide into bicarbonate when the pH value of the solution is about 7-10, stirring for more than 30 minutes to dissolve chitosan, and defoaming to obtain a transparent chitosan solution; the stabilizer is 0.3-5.0 mol/kg of final concentration^-1Urea or 0.3-1.2 mol/kg^-1One or a mixture of two of thiourea; preferably, the final concentration of the stabilizer is 1.0-4.0 mol/kg^-1Urea or 0.4-1.0 mol/kg^-1One or a mixture of two of thiourea; preferably, the final concentration of the bicarbonate is 0.3-1.2 mol-kg^-1；

(3) Preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath; the coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%;

the bicarbonate is a single bicarbonate aqueous solution or a mixture of multiple bicarbonates aqueous solutions.

8. The method for preparing chitosan fiber material of claim 7, wherein: the method for adjusting the concentration of sodium hydroxide or potassium hydroxide in the mixture in the step (2) comprises the following steps: filtering and squeezing the mixture obtained in the step (1) to remove excessive sodium hydroxide or potassium hydroxide aqueous solution, and adding a proper amount of water to ensure that the final concentration of the sodium hydroxide or the potassium hydroxide in the mixture is 0.2-1.5 mol/kg^-1。

9. The method for preparing chitosan fiber material of any of claims 1-8, wherein the bicarbonate comprises one or more of alkali metal bicarbonate, alkaline earth metal bicarbonate, and ammonium bicarbonate, preferably sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, and magnesium bicarbonate.

10. The method for preparing chitosan fiber material of any one of claims 1 to 8, wherein in step (2), the air bubbles in the chitosan solution can be removed by high speed centrifugation, or by common methods of vacuum static elimination and continuous defoaming, so as to obtain the chitosan spinning solution.

11. A chitosan fiber material, which is prepared by the method for preparing the chitosan fiber material of any one of claims 1 to 10.

12. A method for preparing functional chitosan fiber, characterized in that functional organic or inorganic additives are introduced into the chitosan fiber obtained by any one of the methods of claims 1 to 10, or different macromolecules are introduced for blending spinning, and the additives can be added through spinning dope or coagulation bath.

13. The method according to claim 12, wherein the functional organic or inorganic additive comprises one or more of a plasticizer, a strengthening agent, a refractory additive, a dye, an optical stabilizer, an antibacterial bacteriostatic agent, a conductive material, and a surfactant.

14. The method of claim 12, wherein the functional organic or inorganic additive comprises graphene and derivatives thereof, carbon nanotubes and derivatives thereof, metal or metal oxide nanoparticles, organic framework compounds, or molybdenum disulfide.

15. The preparation method of claim 12, wherein the polymer blended and spun comprises polymer nanofibers, cellulose and its derivatives, animal protein, vegetable protein, collagen, alginate, conductive polymer, polyethylene glycol, and polyvinyl alcohol.

16. A functional chitosan fiber, which is prepared by the preparation method of the functional chitosan fiber of any one of claims 12 to 15.

Technical Field

The invention belongs to the field of natural polymers and polymer materials, and particularly relates to a preparation method of a chitosan fiber material.

Background

The chitosan is a deacetylated product of chitin, and when the N-deacetylation degree of the chitin is more than 55%, the chitin is converted into chitosan which can be dissolved in an acidic aqueous solution. The chitosan fiber material is a multifunctional polymer material with certain mechanical strength, which is prepared by using chitosan as a main raw material through the processes of dissolving, spinning, gelatinizing, drafting, plasticizing and the like. The chitosan fiber material has good biocompatibility and biodegradability, also has antibacterial property, can promote the healing of wounds, has the hemostatic effect, and has wide application in the fields of biological medical treatment, textile materials and the like. The preparation technology of chitosan fiber is the research hotspot of the research in the technical field of new materials at present.

The mechanical property of the chitosan fiber is an important factor influencing the application range of the chitosan gel. In order to prepare the high-strength and high-toughness chitosan fiber material, a proper solvent is selected to regulate the self-assembly behavior of molecular chains in the process of chitosan solution-gel transformation. The chitosan has a large amount of hydrogen bonds among molecules, high crystallinity and insolubility in water and common organic solvents, thereby limiting the application of the chitosan. The traditional method for preparing chitosan fiber is to use low-concentration acetic acid aqueous solution or hydrochloric acid aqueous solution as a solvent to dissolve chitosan, then use alkali liquor to neutralize, convert the chitosan solution into fiber gel, and obtain the chitosan fiber after drying. The chitosan fiber prepared by the acid solvent has poor mechanical strength, and the chitosan acid stock solution can be slowly degraded in the process of placing.

In recent years, inspired by the low-temperature dissolution of cellulose by an alkali/urea aqueous solvent system, the scientists of China found that chitosan can be dissolved in an alkali/urea aqueous solution at a low temperature, which changes the prior cognition that chitosan can only be dissolved in an acid aqueous solvent, and simultaneously provides a new idea for preparing chitosan fiber materials.

After chitosan is dissolved in an alkali/urea solvent, under the induction of organic solvent molecules, chitosan molecular chains are assembled to form a three-dimensional network structure woven by nano fibers through hydrogen bond action and hydrophobic action, and the obtained chitosan fibers have better toughness and higher elongation at break. The alkaline aqueous solvents currently used for dissolving chitosan are lithium hydroxide-sodium hydroxide-urea combination (patent 201110099176.3), lithium hydroxide-potassium hydroxide-urea combination (patent 201310405191.5), sodium hydroxide-urea combination (Zhang W, Xia W.Disolution and stability of chitosan in sodium hydroxide/urea aqueous solution [ J ]. Journal of Applied Polymer Science,2014,131(3): 1082. multidot. 1090.), lithium hydroxide-urea combination (Li C, Han Q, Guan Y, et al. Michael reaction of chitosan with acrylic acid in aqueous solution of alkali-urea solution [ J ]. Polymer, 20772 (8): 2087. multidot. 2085.). These combination solvents require one or more freeze-thaw cycles to solubilize the chitosan. The freezing-unfreezing process consumes a large amount of energy and is a great problem for industrial production. In addition, these alkaline solvents are highly corrosive because they use alkaline hydroxides, and the pH of the aqueous solution is greater than 13.

At present, no report is provided for preparing a high-strength and high-toughness chitosan fiber material by dissolving chitosan in a weakly alkaline inorganic salt water solvent.

Disclosure of Invention

The invention aims to solve the defects in the prior art and provide a novel method for preparing a high-strength and high-toughness chitosan fiber material. The application is characterized in that the chitosan is dissolved by using the weak alkaline aqueous solvent system solvent, freezing-unfreezing is not needed, and the chitosan solution is used for preparing the high-strength and high-toughness multifunctional chitosan fiber material.

The technical scheme provided by the invention is as follows:

in a first aspect, a method for preparing a chitosan fiber material is provided, which comprises the following steps:

(1) preparing a weakly alkaline aqueous solution, wherein the weakly alkaline aqueous solution consists of bicarbonate, a stabilizer and water; wherein the final concentration of bicarbonate is: 0.2 to 1.5 mol/kg^-1The final concentration of the stabilizer is 0.3-5.0 mol/kg^-1Urea or 0.3-1.2 mol/kg^-1Thiourea or a mixture of the two, and the balance water;

(2) preparing a chitosan weakly alkaline aqueous solution: adding chitosan into the alkalescent aqueous solution obtained in the step (1), continuously stirring for more than 30 minutes at the temperature of not more than 35 ℃, dissolving the chitosan, and defoaming to obtain a transparent chitosan solution;

(3) preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath. The coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%; the aperture of the spinneret orifice is 0.05 mm-0.3 mm;

the bicarbonate is a single bicarbonate aqueous solution or a mixture of multiple bicarbonates aqueous solutions.

Preferably, the concentration of the bicarbonate in the weak alkaline aqueous solution prepared in the step (1) is 0.3-1.2 mol/kg^-1The stabilizer is 1 to 4.0 mol/kg^-1Urea or 0.4-1.0 mol/kg^-1Thiourea and the balance water.

In a second aspect, a method for preparing a chitosan fiber material is provided, which comprises the following steps:

(1) dissolving chitosan in a stabilizer at a concentration of 0.1-1.0 mol/kg^-1Adding a proper amount of alkali to the inorganic or organic acid aqueous solution to adjust the pH of the solution to be neutral, and separating out chitosan; the stabilizer is 0.3-5.0 mol/kg of final concentration^-1Urea or 0.3-1.2 mol/kg^-1Thiourea or a mixture of the two; the alkali for adjusting the pH of the solution is any one of alkali hydroxide, alkali metal carbonate, alkaline earth metal carbonate, alkali metal bicarbonate, alkaline earth metal bicarbonate, ammonia water, ammonium carbonate and ammonium bicarbonate or a mixture of the alkali hydroxide, the alkali metal carbonate, the alkaline earth metal bicarbonate and the ammonia water; the inorganic or organic acid is preferably acetic acid, hydrochloric acid, citric acid, etc；

(2) Adding bicarbonate into the mixture of chitosan and water in the step (1), continuously stirring for more than 10 minutes under the condition of the freezing point to 35 ℃, dissolving the chitosan, and defoaming to obtain a transparent chitosan solution; the final concentration of the bicarbonate is 0.2-1.5 mol/kg^-1；

(3) Preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath. The coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%; the aperture of the spinneret orifice is 0.05 mm-0.3 mm;

the bicarbonate is a single bicarbonate aqueous solution or a mixture of multiple bicarbonates aqueous solutions.

Preferably, the final concentration of the stabilizer added in the step (1) is 1.0-4.0 mol-kg^-1Urea or 0.4-1.0 mol/kg^-1Thiourea; the final concentration range of the bicarbonate in the step (2) is 0.3-1.2 mol/kg^-1。

In a third aspect, a method for preparing a chitosan fiber material is provided, which comprises the following steps:

(1) preparing an alkaline aqueous solution, wherein the alkaline aqueous solution consists of alkaline hydroxide or carbonate, a stabilizing agent and water; wherein the final concentration of the alkali hydroxide is 0.2 to 1.5 mol/kg^-1The final concentration of carbonate is 0.10 to 0.75 mol/kg^-1The final concentration of the stabilizer is 0.3-5.0 mol/kg^-1Urea or 0.3-1.2 mol/kg^-1Thiourea or a mixture of the thiourea and the water;

(2) adding chitosan into the alkaline aqueous solution obtained in the step (1), introducing carbon dioxide, continuously stirring for more than 30 minutes under the condition that the freezing point is 35 ℃, dissolving the chitosan when the pH value of the solution is about 7-10, and defoaming to obtain a transparent chitosan solution;

(3) preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath. The coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%; the aperture of the spinneret orifice is 0.05 mm-0.3 mm;

the hydroxide is metal hydroxide, ammonium hydroxide, quaternary ammonium base, preferably sodium hydroxide, potassium hydroxide, ammonium hydroxide or a mixture thereof; the carbonate is preferably sodium carbonate, potassium carbonate, ammonium carbonate, or a mixture thereof.

Preferably, the final concentration of the hydroxide in the alkaline aqueous solution prepared in the step (1) is 0.3-1.2 mol/kg^-1The final concentration of carbonate is 0.15-0.6 mol/kg^-1The final concentration range of the stabilizer is preferably 1.0-4.0 mol/kg^-1Urea or 0.4-1.0 mol/kg^-1Thiourea and the balance water.

In a fourth aspect, a method for preparing a chitosan fiber material is provided, which comprises the following steps:

(1) chitin and the mass molar concentration of 8.0-12.5 mol/kg^-1Mixing sodium hydroxide aqueous solution or potassium hydroxide aqueous solution, heating to perform deacetylation reaction to generate chitosan;

(2) adjusting the final concentration of sodium hydroxide or potassium hydroxide in the mixture obtained in (1) to 0.2-1.5 mol/kg^-1Cooling the mixture to a temperature between freezing and 35 deg.C, addingAdding a stabilizer, introducing carbon dioxide at room temperature, converting sodium hydroxide or potassium hydroxide into bicarbonate when the pH value of the solution is about 7-10, stirring for more than 30 minutes to dissolve chitosan, and defoaming to obtain a transparent chitosan solution; the stabilizer is 0.3-5.0 mol/kg of final concentration^-1Urea or 0.3-1.2 mol/kg^-1One or a mixture of two of thiourea; preferably, the final concentration of the stabilizer is 1.0-4.0 mol/kg^-1Urea or 0.4-1.0 mol/kg^-1One or a mixture of two of thiourea; preferably, the final concentration of the bicarbonate is 0.3-1.2 mol-kg^-1。

(3) Preparing a chitosan fiber material: directly spraying the chitosan weakly alkaline aqueous solution obtained in the step (2) by adopting a wet spinning method, allowing the chitosan weakly alkaline aqueous solution to enter a coagulating bath for regeneration, or spraying the chitosan weakly alkaline aqueous solution by adopting a dry spraying wet spinning method, solidifying and regenerating the chitosan weakly alkaline aqueous solution in the coagulating bath, stretching the obtained filaments, removing a chemical reagent by using deionized water, oiling, drying and winding to obtain chitosan fibers; the coagulation bath for spinning can be a single coagulation bath or a multi-stage coagulation bath. The coagulating bath adopts any one or more of mixed aqueous solution of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acid; the preferable salt concentration is 0-40 wt%, the acid concentration is 0-20 wt%, and the alcohol concentration is 0-100 wt%; the aperture of the spinneret orifice is 0.05 mm-0.3 mm;

the method for adjusting the concentration of sodium hydroxide or potassium hydroxide in the mixture in the step (2) comprises the following steps: filtering and squeezing the mixture obtained in the step (1) to remove excessive sodium hydroxide or potassium hydroxide aqueous solution, and adding a proper amount of water to ensure that the final concentration of the sodium hydroxide or the potassium hydroxide in the mixture is 0.2-1.5 mol/kg^-1。

The bicarbonate is a single bicarbonate aqueous solution or a mixture of multiple bicarbonates aqueous solutions.

Preferably, the bicarbonate includes alkali metal bicarbonate, alkaline earth metal bicarbonate, ammonium bicarbonate, preferably one or more of sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, magnesium bicarbonate.

Preferably, in order to obtain a high-quality chitosan spinning solution, in the step (2) of the method, the air bubbles in the chitosan solution can be removed by a high-speed centrifugation method, or the air bubbles in the chitosan solution can be removed by a common method of decompression static elimination and continuous defoaming to obtain the chitosan spinning solution. According to the difference of the defoaming mode and the viscosity of the chitosan solution, the defoaming time of the chitosan solution is more than 0.1 h.

In a fourth aspect, a chitosan fiber material is provided, which is prepared by any one of the above methods for preparing chitosan fiber materials.

In a fifth aspect, a method for preparing functional chitosan fiber is provided, wherein functional organic or inorganic additives or different polymers are introduced to perform blend spinning during the preparation of the chitosan fiber, and the additives can be added through a spinning solution or a coagulation bath.

Preferably, the functional organic or inorganic additive comprises one or more of a plasticizer, a reinforcing agent, a refractory additive, a dye, an optical stabilizer, an antibacterial bacteriostatic agent, a conductive material and a surfactant.

Preferably, the functional organic or inorganic additive comprises graphene, carbon nanotubes, silicon dioxide or molybdenum disulfide, and the polymer blended and spun comprises cellulose and derivatives thereof, animal protein, vegetable protein, alginate and conductive polymer.

In a sixth aspect, a functional chitosan fiber material is provided, which is prepared by any one of the above methods for preparing a functional chitosan fiber material.

The chitosan fiber of the invention can be blended by adding other materials to enhance the performance of the chitosan fiber. Inorganic substances, polymers, fillers, etc. may be added to the chitosan solution. Inorganic substances such as silica, iron oxide, ferroferric oxide, clay, titanium dioxide, etc. Polymers such as cellulose, collagen, alginic acid, polyethylene glycol, polyvinyl alcohol, etc. Fillers such as carbon black and the like. Fiber reinforcement materials such as glass fiber, carbon fiber, graphene and its derivatives, carbon nanotube and its derivatives, cellulose whisker, chitin whisker, etc. can also be added. At least one of these additives or fillers may be added. The additives or fillers may be added to the solvent in advance, or may be added after dissolution.

Compared with the prior art, the invention provides a method for quickly and effectively obtaining the high-quality chitosan fiber material with low cost, no pollution. The invention has the advantages that the adopted bicarbonate aqueous solution is a weakly alkaline solvent system, has no corrosivity, has good solution stability, does not need freezing and unfreezing, and has mild conditions in the process of preparing chitosan fiber from the chitosan solution, and the preparation method is green and environment-friendly and has no toxic and harmful substance residues. Compared with the chitosan fiber prepared by the traditional acid dissolving method, the chitosan fiber prepared by the method provided by the invention has better toughness and higher strength, and has wide application prospect in the fields of biomedical materials and textile materials.

Detailed Description

Further features and advantages of the present invention will be understood from the following detailed description. The examples provided are merely illustrative of the method of the present invention and do not limit the remainder of the disclosure in any way.

The chitosan used in the following examples and comparative examples is extracted from natural shrimp shell, crab shell, squid parietal bone, diatom, insect and other organisms containing alpha-chitin and beta-chitin, and the specific extraction steps are immersing with alkali liquor to remove protein, immersing with acid liquor to remove inorganic salt, decoloring with oxidant, washing with water and drying to obtain purified chitin. The chitosan is prepared by deacetylation reaction of chitin in sodium hydroxide or potassium hydroxide aqueous solution, or is a pure chitosan product purchased from a reagent company.