A high-strength chitosan fiber and preparation method thereof

Abstract

The present invention discloses a high-strength chitosan fiber and a preparation method thereof. Chitosan powder is added to an acidic aqueous solution, stirred to completely dissolve the chitosan powder, and a chitosan aqueous solution is obtained; the obtained chitosan aqueous solution is spun into an anionic surfactant solution to obtain a fibrous chitosan-based gel; the obtained fibrous gel is oriented by drafting, and then transferred to an alkaline solution, and washed with deionized water to obtain a fibrous chitosan gel with high wet strength; and chitosan fiber is obtained after drying. The present invention can significantly improve the strength of chitosan fiber. Compared with the traditional method, the present invention is low-cost, green and environmentally friendly, simple in process, high in wet strength, compatible with existing wet spinning machines, and has great application potential in the fields of textiles, flexible smart fabrics, surgical sutures, etc.

Description

Technical Field

[0001] The invention belongs to the field of chitosan materials, and relates to a chitosan fiber material preparation technology, in particular to a high-strength chitosan fiber and a preparation method thereof. Background Art

[0002] Chitosan is a product of chitosan deacetylation, and its main chemical structure is 2-amino-2-deoxy-D-glucopyranose and 2-acetylamino-2-deoxy-D-glucopyranose residues. Chitosan has film-forming, hygroscopic, cationic polyelectrolyte, antibacterial, low immunogenicity, biocompatibility and biodegradability, and is widely used in biomedicine, drug delivery, hemostatic materials, wound dressings, regenerative tissue engineering and other fields.

[0003] At present, chitosan fibers are widely used in surgical sutures, antibacterial fabrics, high-end sanitary care products, etc., but pure chitosan fibers have poor mechanical strength and need to be blended with other fibers, which affects the biocompatibility of chitosan fibers. Traditional wet spinning uses the acid dissolution and alkali precipitation method to prepare chitosan fibers, but the resulting fibers have poor mechanical strength. In recent years, researchers have developed a new alkali / urea system to dissolve chitosan and then re-gel it in alcohol or salt solutions, providing a new idea for the preparation of chitosan fiber materials, but this process often requires multiple freeze-thaw cycles and consumes energy. Therefore, it is of great significance to study a low-cost, green and environmentally friendly technology with simple process and compatible with the existing wet spinning system to improve the mechanical properties of chitosan fibers.

[0004] Prior art CN201910105575.2 discloses a method for preparing chitosan fiber material, which comprises dissolving chitosan with urea or thiourea or a prepared alkaline solution, and after degassing, directly spinning the chitosan into a coagulation bath for regeneration by wet spinning or spinning the chitosan by dry-wet spinning and then coagulating and regenerating the chitosan fiber in a coagulation bath. The obtained filaments are stretched, and the chemical reagents are removed with deionized water, and then the chitosan fibers are obtained after oiling, drying and winding. The coagulation bath adopts a mixed aqueous solution of any one or more of amide, dimethyl sulfoxide, ethyl acetate, acetone, alcohols, salts and acids. Although the chitosan fiber prepared by this technology has good strength, it only has good dry strength and low wet strength. In addition, cross-linking components are introduced, which reduces the biocompatibility of the fiber product and cannot meet the application requirements of medical products. Summary of the invention

[0005] In view of the problem that the mechanical properties (wet strength) of chitosan fibers are currently relatively weak, the present invention provides a wet spinning method for high-strength chitosan fibers.

[0006] A wet spinning method for high-strength chitosan fiber comprises the following steps:

[0007] Step 1, adding chitosan powder to a certain amount of acidic aqueous solution, stirring to completely dissolve the chitosan powder, to obtain a chitosan aqueous solution;

[0008] Step 2, degassing the obtained chitosan aqueous solution to obtain a transparent chitosan aqueous solution;

[0009] Step 3, using the transparent chitosan aqueous solution obtained in step 2 as the original spinning solution, directly spinning it into a coagulation bath by a wet spinning method or by a dry-jet wet spinning method to obtain a fibrous chitosan-based gel;

[0010] Step 4, stretching and orienting the fibrous chitosan-based gel obtained in step 3;

[0011] Step 5, placing the fiber gel obtained in step 4 into an alkaline elution bath for elution to obtain a regenerated chitosan fiber gel;

[0012] Step 6: Wash the regenerated chitosan fiber gel obtained in step 5 with deionized water, dry it, and collect it to obtain the regenerated chitosan fiber.

[0013] Preferably, in step 1, the acidic aqueous solution is any one of hydrochloric acid, acetic acid, oxalic acid, and citric acid, or a mixture of several of them.

[0014] Preferably, in step 1, the chitosan solution has a mass concentration of 1-5% and a molecular weight greater than 2000000 g / mol.

[0015] Preferably, in step 2, the degassing treatment is high-speed centrifugation, negative pressure standing, microwave degassing or scraping film thinning.

[0016] Preferably, in step 3, the coagulation bath is alkylbenzene sulfonate, alkyl sulfonate ester salt, alkyl sulfonate, alkyl sulfate, fatty alcohol sulfate, fatty alcohol polyoxyethylene ether sulfate, α -Any one or a mixture of olefin sulfonate, alkyl sulfonic acid acetamide, alkyl succinate sulfonate, alcoholamine alkylbenzene sulfonate.

[0017] Further preferably, in step 3, the concentration of the coagulation bath is 0.1-1 mol / L and the temperature is 50-90°C.

[0018] Preferably, in step 4, the stretching orientation stretching ratio is 150-300%.

[0019] Preferably, in step 5, the elution bath is any one of potassium hydroxide, sodium hydroxide, lithium hydroxide, and ammonia water, or a mixture thereof, with a concentration of 0.01-5 mol / L.

[0020] Preferably, in step 6, the drying temperature is 60-80°C.

[0021] Preferably, in step 3, the morphology of the fibrous chitosan-based gel obtained by spinning includes hollow fibers, core-shell structured fibers, tubes, membranes or blocks.

[0022] Preferably, a functional filler is added to the chitosan aqueous solution in step 1, and the functional filler includes an organic filler or an inorganic filler, specifically one or more of a metal organic framework compound, a covalent organic framework, a metal / metal oxide nanoparticle, montmorillonite, a mica sheet, graphene, a multi-walled carbon nanotube, an aggregation-induced emission material, a quantum dot, polypyrrole, and polydopamine.

[0023] The invention also protects a high-strength chitosan fiber prepared by the above preparation method.

[0024] The principle of the present invention is as follows:

[0025] Chitosan powder is dissolved in an acidic solution and exhibits polycation electrolyte properties. In a coagulation bath, it can electrostatically interact with anionic surfactants in the coagulation bath, undergo sol-gel transformation, and obtain a fibrous gel; the anionic surfactant acts as a template to shape the gel into a fibrous shape. The dynamic electrostatic interaction formed between the positively charged chitosan molecular chain and the negatively charged anion makes the gel have good drafting properties. After drafting orientation, the orientation degree of the chitosan molecular chain is further improved. Under the action of the elution bath of the alkaline solution, the electrostatic effect is destroyed, the anionic surfactant is precipitated in situ as a sacrificial template and removed, and the positively charged chitosan molecular chain is neutralized by the alkali and crystallized while maintaining a highly oriented structure, thereby obtaining a highly oriented water-insoluble fibrous pure chitosan gel. The obtained pure chitosan fiber has a high degree of crystallinity and can maintain high mechanical properties in a wet environment, that is, it has a high wet strength. At the same time, because the anionic surfactant is washed away, the chitosan fiber of the present invention has good biocompatibility and maintains almost the same biocompatibility as the raw material chitosan.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The chitosan of the present invention has high purity and high wet strength. The high purity leads to good biocompatibility of the present invention, and the high wet strength enables the present invention to be used in high humidity environments. Moreover, the present invention is a biodegradable material. Therefore, the present invention is particularly suitable for use as a material that can come into contact with human tissue fluid, such as hemostatic materials, wound dressings, regenerative tissue engineering, etc., which expands the application range and product quality of chitosan fiber. DETAILED DESCRIPTION

[0028] The present invention is further described below by way of examples. It should be understood that the examples of the present invention are intended to illustrate the present invention rather than to limit the present invention. Simple modifications to the present invention made according to the essence of the present invention all fall within the scope of protection claimed in the present invention.

[0029] Example 1

[0030] Dissolve 1g of chitosan powder with a deacetylation degree of 85% in a certain concentration of dilute hydrochloric acid, adjust the pH to 5.5-6.5, and obtain a chitosan aqueous solution with a mass fraction of 1%. Let it stand for 1 day under negative pressure to eliminate bubbles. After pressurization, the chitosan solution is spun through a needle with an aperture of 250μm and enters a 0.1mol / L anionic surfactant solution at a temperature of 30°C. The resulting fibrous gel is stretched 1 times and then enters a 0.5mol / L sodium hydroxide solution. It is washed with deionized water and then wound and collected to obtain chitosan fibers. The universal electronic testing machine measured the fiber's wet breaking strength to be 25MPa, the breaking elongation to be 23%, and the Young's modulus to be 124MPa.

[0031] Example 2

[0032] 2g of chitosan powder with a deacetylation degree of 85% was dissolved in a certain concentration of dilute hydrochloric acid, and the pH was adjusted to 5.5-6.5 to obtain a chitosan aqueous solution with a mass fraction of 2%. It was left to stand for 1 day under negative pressure to eliminate bubbles. The chitosan solution was pressurized and spun through a needle with an aperture of 250μm, and entered a 0.25mol / L anionic surfactant solution at a temperature of 70°C. The resulting fibrous gel was stretched twice and entered a 0.5mol / L sodium hydroxide solution. After washing with deionized water and drying, chitosan fibers were collected. The universal electronic testing machine measured the fiber's dry breaking strength to be 276MPa, the breaking elongation to be 2.5%, and the Young's modulus to be 2GPa; after the dried chitosan fiber was immersed in deionized water again, the fiber's wet breaking strength was measured by a universal electronic testing machine to be 101MPa, the breaking elongation to be 10%, and the Young's modulus to be 842MPa.

[0033] Example 3

[0034] Dissolve 2g of chitosan powder with a deacetylation degree of 85% in a certain concentration of dilute hydrochloric acid, adjust the pH to 5.5-6.5, and obtain a chitosan aqueous solution with a mass fraction of 2%. Let it stand for 1 day under negative pressure to eliminate bubbles. The chitosan solution is pressurized and spun through a needle with an aperture of 200μm, and enters a 0.5mol / L anionic surfactant solution at a temperature of 70°C. The resulting fibrous gel is stretched twice and then enters a 1mol / L sodium hydroxide solution. After washing and drying with deionized water, it is collected and placed back in deionized water. The universal electronic testing machine measured the fiber's wet breaking strength to be 123MPa, the breaking elongation to be 11%, and the Young's modulus to be 905MPa.

[0035] The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Although the present invention is described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing high-strength chitosan fiber, characterized in that: The steps include: Step 1, adding chitosan powder to a certain amount of acidic aqueous solution, stirring to completely dissolve the chitosan powder, to obtain a chitosan aqueous solution; Step 2, degassing the obtained chitosan aqueous solution to obtain a transparent chitosan aqueous solution; Step 3: Using the transparent chitosan aqueous solution obtained in step 2 as the original spinning solution, directly spinning it into a coagulation bath by a wet spinning method to obtain a fibrous chitosan-based gel, wherein the coagulation bath is a coagulation bath containing an anionic surfactant, the coagulation bath temperature is 20-90° C., and the concentration of the coagulation bath is 0.1-1 mol / L; Step 4, stretching and orienting the fibrous chitosan-based gel obtained in step 3, with a stretch ratio of 150-300%; Step 5: placing the fiber gel obtained in step 4 into an alkaline elution bath for elution to obtain a regenerated chitosan fiber gel; Step 6: The regenerated chitosan fiber gel obtained in step 5 is washed with deionized water, dried, and collected to obtain high-strength regenerated chitosan fibers.

2. The method for preparing high-strength chitosan fiber according to claim 1, characterized in that: In step 1, the acidic aqueous solution is any one of hydrochloric acid, acetic acid, citric acid, and oxalic acid, or a mixture thereof.

3. The method for preparing high-strength chitosan fiber according to claim 1, characterized in that: In step 2, the degassing treatment includes high-speed centrifugation, negative pressure standing, microwave degassing or scraping film thinning.

4. The method for preparing high-strength chitosan fiber according to claim 1, characterized in that: In step 3, the anionic surfactant is selected from any one of alkylbenzene sulfonate, alkyl sulfonate ester salt, alkyl sulfonate, alkyl sulfate, fatty alcohol sulfate, fatty alcohol polyoxyethylene ether sulfate, α-olefin sulfonate, alkylsulfonic acid acetamide, alkyl succinate sulfonate, and alcoholamine alkylbenzene sulfonate, or a mixture thereof.

5. The method for preparing high-strength chitosan fiber according to claim 1, characterized in that: In step 5, the elution bath is any one of potassium hydroxide, sodium hydroxide, lithium hydroxide, and ammonia water, or a mixture thereof.

6. The method for preparing high-strength chitosan fiber according to any one of claims 1 to 5, characterized in that: In step 3, the morphology of the fibrous chitosan-based gel obtained by spinning includes hollow fibers, core-shell structured fibers, tubes, membranes or blocks.

7. The method for preparing high-strength chitosan fiber according to any one of claims 1 to 5, characterized in that: A functional filler is added to the chitosan aqueous solution in step 1, wherein the functional filler includes one or more of a metal organic framework compound, a covalent organic framework, metal / metal oxide nanoparticles, montmorillonite, mica sheets, graphene, multi-walled carbon nanotubes, aggregation-induced emission materials, quantum dots, polypyrrole, and polydopamine.

8. A high-strength chitosan fiber, characterized by: Prepared by the preparation method according to any one of claims 1 to 7.