Preparation method of cross-linked composite chitosan solution and chitosan fiber thereof

Abstract

The invention relates to the technical field of natural polymer material processing, and discloses a cross-linked composite chitosan solution which is composed of the following components in percentage by mass: 1%-5% of chitosan, 0.1%-5% of a cross-linking agent, 0.1%-5% of acetic acid and the balance of water, and the cross-linked composite chitosan solution is prepared from the following components in percentage by mass: 1%-5% of chitosan, 0.1%-5% of a cross-linking agent, 1%-5% of acetic acid and the balance of water. The cross-linking agent is one or more of glutaraldehyde, citric acid and epoxy chloropropane. According to the cross-linked composite chitosan solution and the preparation method of the chitosan fiber of the cross-linked composite chitosan solution, the adaptability of the cross-linked composite chitosan solution in a human body can be further improved and the immunoreaction can be reduced through a cross-linking reaction, so that the enhancement of the biocompatibility of the cross-linked composite chitosan solution can be ensured; by selecting different cross-linking agents and controlling the cross-linking degree, the biodegradation rate of the chitosan can be adjusted to a certain extent, so that the chitosan is more suitable for specific medical or environmental application requirements, and in addition, the water resistance of the chitosan can be remarkably improved through the cross-linking effect.

Description

Technical Field

[0001] The present invention relates to the technical field of natural polymer material processing, and specifically to a preparation method of a cross-linked composite chitosan solution and chitosan fibers thereof. Background Art

[0002] Chitosan is the only basic polysaccharide polymer in nature, with biocompatibility, biodegradability, and natural antibacterial properties. It is a functional biomaterial with greater application potential than cellulose. There are a large number of amino groups in the molecular structure of chitosan, which can adsorb positively charged protons, so that chitosan molecules dissolve in acid solutions under the action of the same-charge repulsion force. However, common acids such as acetic acid and hydrochloric acid will cause chitosan molecules to hydrolyze quickly, affecting the stability and applicability of chitosan solutions. In addition, chitosan solutions have a low concentration but high viscosity. During the material forming process, due to the low solid content and severe water loss and shrinkage, it is difficult for the material to form a good structure, and the mechanical properties of the material are very poor. Therefore, improving the properties and application performance of chitosan solutions still has research value and practical significance.

[0003] The problems currently faced by chitosan solutions mainly focus on their stability and formability. Due to the large degree of polymerization of chitosan molecules and strong water absorption, high viscosity is also exhibited at low concentrations, which makes it difficult to maintain the uniformity and stability of the solution. At the same time, chitosan is prone to degradation in acidic solutions. Over time, the viscosity of the solution will gradually decrease, affecting its long-term stability. In addition, the stability of chitosan solutions is greatly affected by the pH value. It is stable in an acidic environment, but in a nearly neutral or alkaline condition, the solubility of chitosan drops sharply, forming an unstable suspension. In addition, some studies are committed to adjusting the pH value of chitosan solutions through simple gas treatment in order to achieve better solubility and stability. For example, by introducing carbon dioxide into a chitosan dispersion, the chitosan is dissolved by the action of carbonic acid, so as to obtain a chitosan solution with a pH value in the range of 6-8, which is suitable for further fiber preparation. There are also studies focusing on improving the mechanical properties of chitosan fibers. For example, by dissolving chitosan in strongly acidic solvents such as hydrochloric acid, acetic acid, and oxalic acid, and then through specific coagulation bath treatment to prepare high-strength chitosan fibers.

[0004] From the perspective of the development of existing technologies, although there have been multiple innovative attempts, challenges still remain in the stability and formability of chitosan solutions. Therefore, it is necessary to design a new solution system based on the characteristics of chitosan molecules, which can not only ensure the long-term stability of the solution but also achieve gentle solidification and molding in the coagulation bath, and is of great significance for improving the performance of chitosan fibers. Considering the advantages and disadvantages of the above methods comprehensively, future research needs to make more efforts in simplifying the preparation process, improving production efficiency, and optimizing product performance to promote the application of chitosan materials in a wider range of fields. Therefore, a preparation method of a cross-linked composite chitosan solution and its chitosan fibers is proposed to solve the above-mentioned problems. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] In view of the deficiencies of the existing technologies, the present invention provides a preparation method of a cross-linked composite chitosan solution and its chitosan fibers, which has the advantages of simple preparation method, low cost, and excellent stability of the chitosan solution, and solves the problems that the chitosan molecules have a large degree of polymerization, strong water absorption, and high viscosity even at low concentrations, which makes it difficult to maintain the homogeneity and stability of the solution.

[0007] (2) Technical solutions

[0008] To achieve the purpose of simple preparation method, low cost, and excellent stability of the chitosan solution, the present invention provides the following technical solution: A cross-linked composite chitosan solution, which is composed of chitosan, a cross-linking agent, acetic acid, and water, and the mass fractions of each component are respectively 1%-5% of chitosan, 0.1%-5% of the cross-linking agent, 0.1%-5% of acetic acid, 1%-5% of acetic acid, and the rest is water; the cross-linking agent is one or several of glutaraldehyde, citric acid, and epichlorohydrin.

[0009] A preparation method of a cross-linked composite chitosan solution, comprising the following steps:

[0010] S1. Raw material preparation: Prepare chitosan (1%-5%), a cross-linking agent (0.1%-5%), acetic acid (1%-5%), and water with the required mass fractions.

[0011] S2. Chitosan dissolution: After accurately weighing the chitosan powder, add it to water containing acetic acid with a corresponding concentration, ensure that the total mass fraction does not exceed 5%, and stir at a certain temperature (such as 50°C - 60°C) until the chitosan is completely dissolved to form a transparent chitosan solution.

[0012] S3. Adding a crosslinking agent: Weigh the crosslinking agent (such as glutaraldehyde, citric acid, epichlorohydrin, etc.) accurately according to the formula, and add it to the chitosan solution, ensuring that the total mass fraction of the crosslinking agent does not exceed 5%. Use a magnetic stirrer or a stirring rod to stir well to make the crosslinking agent evenly distributed;

[0013] S4. Reaction and crosslinking: Place the mixed solution in a constant temperature water bath and continue stirring at a set temperature (such as room temperature or slightly higher) to allow the crosslinking reaction to proceed fully;

[0014] S5. pH value adjustment: Adjust the pH value of the solution by adding an appropriate amount of alkaline solution (such as sodium hydroxide solution) to reach a suitable range to promote the completion of the crosslinking reaction;

[0015] S6. Aging or curing: Let the solution stand and age at a suitable temperature to ensure the complete completion of the crosslinking reaction;

[0016] S7. Filtration and purification: Filter the solution using a filtration device (such as a Buchner funnel, microporous membrane) to remove any undissolved particles or impurities;

[0017] S8. Washing: Wash the filtered solution with deionized water or distilled water multiple times to remove residual acetic acid and other impurities until the pH value of the washing water is close to neutral;

[0018] S9. Detection and analysis: Conduct quality detection on the final crosslinked composite chitosan solution, including measuring its viscosity, pH value, chitosan content, crosslinking agent residue, etc., to ensure that it meets the expected specifications.

[0019] Preferably, in S4, the crosslinking reaction is carried out at a room temperature of about 20°C to 25°C and at a high temperature crosslinking of about 70°C to 90°C.

[0020] Preferably, in S5, the concentration of the sodium hydroxide solution selected is usually between 0.1M and 1M, and the suitable range of the pH value is between 5.5 and 8.0.

[0021] A method for preparing chitosan fibers, comprising the following steps:

[0022] S10. Wet spinning: Extrude the prepared crosslinked composite chitosan solution through a spinneret. There are many tiny holes on the spinneret for forming a continuous fiber stream. The extruded fiber stream immediately enters a coagulation bath, usually water or a solution containing specific salts, which will prompt the chitosan to rapidly solidify into fibers;

[0023] S11. Fiber stretching: The solidified fibers need to be stretched;

[0024] S12. Washing and Drying of Fibers: The stretched fibers need to be thoroughly cleaned. Subsequently, the fibers are sent into a drying device for drying to remove moisture, and finally dry chitosan fibers are obtained.

[0025] Preferably, in S11, the stretching is usually carried out in water or a specific stretching bath, and is achieved by controlling the speed difference of the fibers.

[0026] Preferably, in S12, the drying temperature is between 50°C and 100°C, and the drying time is 30 minutes to 1 hour.

[0027] Preferably, the present invention provides a kind of chitosan fiber.

[0028] (III) Beneficial Effects

[0029] Compared with the prior art, the present invention provides a preparation method of a crosslinked composite chitosan solution and its chitosan fiber, which has the following beneficial effects:

[0030] 1. For the preparation method of the crosslinked composite chitosan solution and its chitosan fiber, through the crosslinking reaction, the adaptability of the crosslinked composite chitosan solution in the human body can be further improved and the immune response can be reduced, which can ensure the enhancement of the biocompatibility of the crosslinked composite chitosan solution. Among them, by selecting different crosslinking agents and controlling the degree of crosslinking, the biodegradation rate of chitosan can be adjusted to a certain extent to make it more suitable for specific medical or environmental application requirements. In addition, the crosslinking effect can significantly improve the water resistance of chitosan and reduce its solubility in the water environment. This characteristic makes the crosslinked composite chitosan solution suitable for more applications in humid environments, such as water treatment, biomedical materials, etc.; at the same time, by precisely controlling the pH value during the preparation process, the solubility and stability of chitosan can be optimized. Therefore, through its unique preparation process and performance improvement, the crosslinked composite chitosan solution provides innovative solutions for applications in multiple fields.

[0031] 2. For the preparation method of the crosslinked composite chitosan solution and its chitosan fiber, through wet spinning and subsequent stretching processes, the mechanical strength of the chitosan fiber can be significantly improved. In step S10, the crosslinked composite chitosan solution is extruded and quickly solidified, and the formed fiber has a relatively high initial strength. And in the stretching process of step S11, the molecular chains are further arranged closely, thus enhancing the tensile strength and durability of the fiber. During the wet spinning process, by precisely controlling the pore diameter of the spinneret and the extrusion speed, fibers with uniform diameter and uniform structure can be obtained. At the same time, through washing and drying treatments, impurities and residual solvents in the fibers can be effectively removed, which not only helps to improve the purity of the fiber, but also enhances its chemical stability in subsequent processing or applications. Description of the Drawings

[0032] Figure 1 The present invention is a flow chart for preparing the cross-linked composite chitosan solution;

[0033] Figure 2 The present invention is a flow chart of the preparation of chitosan fiber. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1

[0036] A cross-linked composite chitosan solution comprises the following raw materials in proportion by weight: 1% chitosan, 0.1% glutaraldehyde, 0.1% cross-linking agent, 1% acetic acid, and the remainder water; the cross-linking agent is glutaraldehyde.

[0037] A method for preparing a cross-linked composite chitosan solution, comprising the cross-linked composite chitosan solution, and further comprising the following steps:

[0038] S1. Raw material preparation: prepare the required mass fractions of chitosan 1%, 0.1%, cross-linking agent 0.1%, acetic acid 1%, and the rest water;

[0039] S2. Dissolving chitosan: After accurately weighing chitosan powder, add it into water containing acetic acid of corresponding concentration, ensuring that the total mass fraction does not exceed 5%, and stir at a temperature of 50° until the chitosan is completely dissolved to form a transparent chitosan solution;

[0040] S3. Adding crosslinking agent: According to the formula, accurately weigh glutaraldehyde and add it to the chitosan solution, ensuring that the total mass fraction of the crosslinking agent does not exceed 5%. Use a magnetic stirrer or a stirring bar to stir thoroughly to make the crosslinking agent evenly distributed;

[0041] S4, reaction and cross-linking: placing the mixed solution in a constant temperature water bath and continuing to stir at a temperature of 20° C. to allow the cross-linking reaction to proceed fully;

[0042] S5. pH adjustment: adjusting the pH of the solution by adding an appropriate amount of sodium hydroxide solution with a concentration of 0.1 M to make the pH value reach 5.5 to promote the completion of the cross-linking reaction;

[0043] S6, aging or curing: Allow the solution to age at a suitable temperature to ensure that the cross-linking reaction is completely completed;

[0044] S7. Filtration and purification: Filter the solution using a Buchner funnel to remove any undissolved particles or impurities.

[0045] S8. Washing: Wash the filtered solution multiple times with deionized water or distilled water to remove residual acetic acid and other impurities until the pH value of the washing water is close to neutral.

[0046] S9. Detection and analysis: Conduct quality detection on the final crosslinked composite chitosan solution, including measuring its viscosity, pH value, chitosan content, crosslinking agent residue, etc., to ensure that it meets the expected specifications.

[0047] In this embodiment, due to the improved biocompatibility and adjustable biodegradability, the crosslinked composite chitosan solution shows great application potential in drug delivery systems, wound healing materials, tissue engineering, etc.

[0048] A method for preparing chitosan fibers, comprising the following steps:

[0049] S10. Wet spinning: Extrude the prepared crosslinked composite chitosan solution through a spinneret. There are many tiny holes on the spinneret for forming a continuous fiber stream. The extruded fiber stream immediately enters a coagulation bath, usually water or a solution containing specific salts, which will prompt the chitosan to rapidly solidify into fibers.

[0050] S11. Fiber stretching: The solidified fibers need to be stretched.

[0051] S12. Fiber washing and drying: The stretched fibers need to be thoroughly washed. Subsequently, the fibers are sent into a drying device for drying to remove moisture, and finally dry chitosan fibers are obtained. The drying temperature is 50°C and the drying time is 1 hour.

[0052] In this embodiment, the wet spinning technique allows for continuous production. Compared with other spinning methods, such as dry spinning, fibers can be produced more efficiently. By optimizing the spinneret design and adjusting the conditions of the coagulation bath, the production efficiency can be further improved and the production cost can be reduced. Each step in this method has a direct impact on the quality of the final product. Through precise process control, such as temperature control, stretching ratio adjustment, and optimization of the washing and drying process, it can be ensured that the produced chitosan fibers have consistent high quality.

[0053] Example 2

[0054] A crosslinked composite chitosan solution, comprising raw materials in the following weight ratio: 5% chitosan, 5% crosslinking agent, 5% acetic acid, and the balance being water; the crosslinking agent is citric acid.

[0055] A method for preparing a cross-linked composite chitosan solution, comprising the cross-linked composite chitosan solution, and further comprising the following steps:

[0056] S1. Raw material preparation: prepare the required mass fractions of chitosan 5%, 5%, cross-linking agent 5%, acetic acid 5%, and the rest water;

[0057] S2. Chitosan dissolution: After accurately weighing chitosan powder, add it into water containing acetic acid of corresponding concentration, ensuring that the total mass fraction does not exceed 5%, and stir at a temperature of 60° until the chitosan is completely dissolved to form a transparent chitosan solution;

[0058] S3. Adding crosslinking agent: According to the formula, accurately weigh citric acid and add it to the chitosan solution, ensuring that the total mass fraction of the crosslinking agent does not exceed 5%. Use a magnetic stirrer or a stirring bar to stir thoroughly to ensure that the crosslinking agent is evenly distributed;

[0059] S4, reaction and cross-linking: placing the mixed solution in a constant temperature water bath and continuing to stir at a temperature of 25°C to allow the cross-linking reaction to proceed fully;

[0060] S5. pH adjustment: adjusting the pH of the solution by adding an appropriate amount of sodium hydroxide solution with a concentration of 1 M to make the pH value reach 8 to promote the completion of the cross-linking reaction;

[0061] S6, aging or curing: Allow the solution to age at a suitable temperature to ensure that the cross-linking reaction is completely completed;

[0062] S7, Filtration and purification: Filter the solution using a microporous membrane to remove any undissolved particles or impurities;

[0063] S8, washing: washing the filtered solution multiple times with deionized water or distilled water to remove residual acetic acid and other impurities until the pH value of the washing water is close to neutral;

[0064] S9. Testing and analysis: The final cross-linked composite chitosan solution is subjected to quality testing, including measuring its viscosity, pH value, chitosan content, cross-linking agent residue, etc., to ensure that it meets the expected specifications.

[0065] In this embodiment, temperature control during the preparation process is equally important for the efficiency of the cross-linking reaction and the performance of the final product. An appropriate reaction temperature can promote a more complete reaction between the cross-linking agent and chitosan, thereby improving the chemical stability and mechanical properties of the product.

[0066] A method for preparing chitosan fiber comprises the following steps:

[0067] S10. Wet spinning: The prepared crosslinked composite chitosan solution is extruded through a spinneret. There are many tiny holes on the spinneret for forming a continuous fiber stream. The extruded fiber stream immediately enters a coagulation bath, usually water or a solution containing specific salts, which will prompt the chitosan to quickly solidify into fibers.

[0068] S11. Fiber stretching: The solidified fibers need to be stretched.

[0069] S12. Fiber washing and drying: The stretched fibers need to be thoroughly washed. Subsequently, the fibers are sent into a drying device for drying to remove moisture, and finally dry chitosan fibers are obtained. The drying temperature is 100 °C and the drying time is 30 minutes.

[0070] In this embodiment, fewer solvents and chemicals are used in the whole production process, and most steps are carried out under mild conditions, reducing the negative impact on the environment. Especially using water as the coagulation bath avoids the use of harmful solvents, making the production process more environmentally friendly.

[0071] In summary, for the preparation method of the crosslinked composite chitosan solution and its chitosan fibers, through the crosslinking reaction, the adaptability of the crosslinked composite chitosan solution in the human body can be further improved and the immune response can be reduced, which can ensure the enhancement of the biocompatibility of the crosslinked composite chitosan solution. Among them, by selecting different crosslinking agents and controlling the crosslinking degree, the biodegradation rate of chitosan can be adjusted to a certain extent to make it more suitable for specific medical or environmental application requirements. In addition, the crosslinking effect can significantly improve the water resistance of chitosan and reduce its solubility in the water environment. This characteristic makes the crosslinked composite chitosan solution applicable to more applications in humid environments, such as water treatment, biomedical materials, etc. At the same time, by precisely controlling the pH value in the preparation process, the solubility and stability of chitosan can be optimized. Therefore, through its unique preparation process and performance improvement, the crosslinked composite chitosan solution provides innovative solutions for applications in multiple fields.

[0072] Moreover, through the wet spinning and subsequent stretching processes, the mechanical strength of chitosan fibers can be significantly improved. In step S10, the crosslinked composite chitosan solution is extruded and quickly solidified, and the formed fibers have relatively high initial strength. And in the stretching process of step S11, the molecular chains are further arranged closely, thus enhancing the tensile strength and durability of the fibers. During the wet spinning process, by precisely controlling the pore diameter of the spinneret and the extrusion speed, fibers with uniform diameter and uniform structure can be obtained. At the same time, through the washing and drying treatments, impurities and residual solvents in the fibers can be effectively removed, which not only helps to improve the purity of the fibers, but also enhances their chemical stability in subsequent processing or applications.

[0073] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0074] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A crosslinked composite chitosan solution, characterized in that: The cross-linked composite chitosan solution is composed of chitosan, a cross-linking agent, acetic acid and water, wherein the mass fractions of the components are 1%-5% and 0.1%-5% of chitosan, 0.1%-5% of a cross-linking agent, 1%-5% of acetic acid and the rest is water; the cross-linking agent is one or more of glutaraldehyde, citric acid and epichlorohydrin.

2. A preparation method of a cross-linked composite chitosan solution, characterized in that: The cross-linked composite chitosan solution according to claim 1 further comprises the following steps: S1. Raw material preparation: prepare chitosan (1%-5%), cross-linking agent (0.1%-5%), acetic acid (1%-5%) and water of required mass fraction; S2. Dissolving chitosan: After accurately weighing chitosan powder, add it into water containing acetic acid of corresponding concentration, ensuring that the total mass fraction does not exceed 5%, and stir at a certain temperature (such as 50°C-60°C) until the chitosan is completely dissolved to form a transparent chitosan solution; S3, adding cross-linking agent: according to the formula, accurately weigh the cross-linking agent (glutaraldehyde, citric acid, epichlorohydrin, etc.), add it to the chitosan solution, ensure that the total mass fraction of the cross-linking agent does not exceed 5%, use a magnetic stirrer or a stirring bar to stir well to make the cross-linking agent evenly distributed; S4, reaction and cross-linking: placing the mixed solution in a constant temperature water bath, and continuing to stir at a set temperature (such as room temperature or slightly higher) to allow the cross-linking reaction to proceed fully; S5. pH adjustment: adjusting the pH of the solution to a suitable range by adding an appropriate amount of alkaline solution (such as sodium hydroxide solution) to promote the completion of the cross-linking reaction; S6, aging or curing: Allow the solution to age at a suitable temperature to ensure that the cross-linking reaction is completely completed; S7. Filtration and purification: Filter the solution using a filtration device (e.g., Buchner funnel, microporous membrane) to remove any undissolved particles or impurities; S8, washing: washing the filtered solution multiple times with deionized water or distilled water to remove residual acetic acid and other impurities until the pH value of the washing water is close to neutral; S9. Testing and analysis: The final cross-linked composite chitosan solution is subjected to quality testing, including measuring its viscosity, pH value, chitosan content, cross-linking agent residue, etc., to ensure that it meets the expected specifications.

3. A crosslinked composite chitosan solution according to claim 1, characterized in that: In S4, the cross-linking reaction is carried out at room temperature of about 20°C to 25°C, and the high temperature cross-linking is carried out at about 70°C to 90°C.

4. A crosslinked composite chitosan solution according to claim 1, wherein: In S5, the concentration of the sodium hydroxide solution is usually between 0.1M and 1M, and the pH value is preferably in the range of 5.5 to 8.

0.

5. A method for preparing chitosan fibers, characterized in that, The steps include: S10, wet spinning: the prepared cross-linked composite chitosan solution is extruded through a spinneret, which has many tiny holes for forming a continuous fiber stream. The extruded fiber stream immediately enters a coagulation bath, usually water or a solution containing specific salts, which will cause the chitosan to coagulate into fibers quickly; S11. Fiber stretching: The solidified fibers need to be stretched; S12. Fiber washing and drying: The stretched fibers need to be thoroughly washed, and then the fibers are sent to a drying device for drying to remove moisture, and finally dry chitosan fibers are obtained.

6. The preparation method of a chitosan fiber according to claim 5, characterized in that: In S11, the stretching is usually carried out in water or a specific stretching bath, and is achieved by controlling the speed difference of the fibers.

7. The preparation method of a chitosan fiber according to claim 1, wherein: In S12, the drying temperature is between 50 °C and 100 °C, and the drying time is 30 minutes to 1 hour.

8. Chitosan fibers prepared by the method according to any one of claims 1 and 5 to 7.

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