Preparation method and application of bio-based polyimide degradable fiber filament

Abstract

The invention relates to the technical field of fiber filaments, in particular to a preparation method and application of bio-based polyimide degradable fiber filaments. The preparation method comprises the following steps that S1, a base material is prepared, lysine is selected as a raw material of the base material, and the base material is obtained after lysine is pretreated; according to the invention, after the lysine is subjected to alkali treatment by the sodium carbonate aqueous solution, carboxyl of the lysine can be deprotonated to form carboxylate ions, the water solubility is increased, the lysine can be swelled by the 1-ethyl-3-methylimidazole acetate, and the catalytic activity of the lysine is improved; the Candida antarctica lipase B can be catalyzed between carboxyl and amino of lysine to form an amido bond, so that lysine-based low polyamide is generated, a regular molecular chain structure is formed, and the regular structure generated through pretreatment can be used as a support in subsequent polymerization treatment, so that stable structure generation of fiber filaments is facilitated; the strength performance of the fiber filament is improved.

Description

Technical Field

[0001] This invention relates to the field of fiber filament technology, specifically to a method for preparing and applying bio-based polyimide biodegradable fiber filaments. Background Technology

[0002] Polyimide fiber filament is a high-performance synthetic fiber with excellent high-temperature resistance, chemical corrosion resistance and mechanical strength. It has outstanding insulation and flame retardancy, and is lightweight and has good dimensional stability.

[0003] In existing technologies, biodegradable polyimide fiber filaments require bio-based materials for their biodegradability, which leads to defects in the regularity of their fiber structure and affects the strength properties of the fiber filaments. Therefore, this invention provides a method for preparing and applying bio-based biodegradable polyimide fiber filaments. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying bio-based polyimide biodegradable fiber filaments. The fiber filaments prepared by this invention not only have good elongation at break but also excellent tensile strength, effectively improving the performance of the fiber filaments.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing bio-based polyimide biodegradable fiber filaments includes the following steps:

[0007] S1: Base material preparation. The raw material for the base material is lysine. After pretreatment, the lysine is used to obtain the base material.

[0008] S2: Preparation of the treatment agent. The raw materials for the treatment agent include pyromellitic dianhydride, ethyl lactate, dimethyl isosorbide, p-phenylenediamine, and ethanol. The mass of the treatment agent is 10-30% of the mass of the base material.

[0009] S3: Mixing treatment, the base material and the treatment agent are mixed to obtain coarse material;

[0010] S4: Preparation of spinning solution, the raw materials of which include crude material, ethanol and propylene carbonate;

[0011] S5: Spinning forming process, the spinning solution is used for spinning forming process to obtain fiber filaments.

[0012] Further, the pretreatment method for lysine in S1 is as follows: lysine is mixed with an aqueous sodium carbonate solution to obtain a mixture. This mixture, along with 1-ethyl-3-methylimidazolium acetate and Candida antarcticis lipase B, is added to a mixer. The mixer is set to 40-60 r / min and stirred for 6-10 min. The mixture is then allowed to stand for 10-20 h, followed by high-temperature sterilization. The resulting product is added to a reaction vessel. An additive solution is then added dropwise to the reaction vessel. After the addition is complete, the reaction vessel temperature is set to 0-5℃ and stirred... The stirring speed is 200-400 r / min, and the constant temperature stirring treatment is carried out for 20-30 min. After the constant temperature stirring treatment is completed, the mixture is allowed to stand at room temperature for 2-4 h. Dilute hydrochloric acid is added to the obtained product to adjust the pH value to 2-3, and the mixture is allowed to stand at room temperature for 1-2 h. The obtained product is filtered to obtain solids. The solids are washed with deionized water 4-6 times, and then placed in an oven and dried at 40-60℃ for 4-6 h to complete the pretreatment of lysine and obtain the base material.

[0013] Furthermore, the mass ratio of lysine to sodium carbonate aqueous solution is 1:(3-4), the mass concentration of sodium carbonate aqueous solution is 6-8%, the mass ratio of the mixture, 1-ethyl-3-methylimidazolium acetate, and Candida antarcticis lipase B is 1:(0.1-0.2):(0.06-0.08), and the mass of the added solution is 10-20% of the mass of the mixture.

[0014] Furthermore, the additive solution is prepared by mixing di-tert-butyl dicarbonate and tetrahydrofuran, with a mass ratio of di-tert-butyl dicarbonate to tetrahydrofuran of 1:(4-5).

[0015] Further, the method for preparing the treatment agent is as follows: pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide are added to a reaction vessel, and under nitrogen atmosphere, the temperature is set at 120–140°C, the stirring speed is 200–400 r / min, and the mixture is stirred at a constant temperature for 4–6 h. The resulting product is added to a mixer, and p-phenylenediamine and ethanol are added to the mixer. The mixer is set to 400–600 r / min and stirred for 40–60 min. The resulting product is then refluxed at 60–80°C for 6–8 h to obtain the treatment agent. The mass ratio of pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide is 1:(0.2–0.4):(0.03–0.05), the mass ratio of p-phenylenediamine and ethanol is 1:(3–5), and the mass of p-phenylenediamine is 20–30% of the mass of the dianhydride.

[0016] Further, the mixing process is as follows: the base material and the treatment agent are added to a reaction vessel, the reaction vessel is set to a temperature of 50-60°C, the stirring speed is 200-400 r / min, and the mixture is stirred at a constant temperature for 40-60 min. The resulting product is washed with distilled water 4-6 times, and then placed in an oven and dried at 50-70°C for 4-6 h to obtain a mixture. The mixture, cresol, isoquinoline, and toluene are added to a flask, nitrogen is introduced into the flask to remove air, and the mixture is heated under reflux at 100-120°C for 4-6 h. The water generated in the reaction is removed by a water separator, and then the temperature is raised to 140-180°C and the treatment continues for 8-10 h to complete the mixing process and obtain the crude material.

[0017] Further, the method for preparing the spinning solution is as follows: after mixing the crude material and ethanol, let it stand for 40-60 minutes. A precipitate is obtained from the product obtained after standing. The process of mixing and standing with ethanol and precipitation is repeated 3-5 times. The obtained product is sent to an oven and dried at 40-60°C for 6-8 hours to obtain a dry material. The dry material and propylene carbonate are added to a reaction vessel. The reaction vessel is set at 50-60°C and the stirring speed is 60-100 r / min. The mixture is stirred at a constant temperature for 2-4 hours. The obtained product is filtered and degassed under vacuum to obtain the spinning solution.

[0018] Furthermore, the mass ratio of crude material to ethanol is 1:(3-4), and the mass ratio of dry material to propylene carbonate is 1:(7-9).

[0019] Furthermore, the spinning forming process is as follows: the spinning solution is fed into the spinning equipment through a metering pump to complete the spinning forming process and obtain fiber filaments. The spinning equipment is set to a temperature of 280-320℃, a spinneret diameter of 0.1-0.3mm, and a winding speed of 200-400m / min.

[0020] Furthermore, the application of a method for preparing bio-based polyimide biodegradable fiber filaments is described, wherein the fiber filaments are used in fabrics and composite materials.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. In this invention, during the preparation of the fiber filament, lysine is pretreated. Lysine undergoes alkaline treatment with sodium carbonate aqueous solution, which deprotonates the lysine carboxyl group to form a carboxylate ion, increasing its water solubility. 1-Ethyl-3-methylimidazolium acetate swells lysine, enhancing its catalytic activity. Candida antarcticis lipase B catalyzes the formation of an amide bond between the carboxyl and amino groups of lysine, thereby generating lysine-based oligoamides and forming a regular molecular chain structure. This regular structure generated after pretreatment can serve as a support in subsequent polymerization processes, facilitating the stable formation of the fiber filament structure and improving its strength properties.

[0023] 2. In this invention, di-tert-butyl dicarbonate can react with ε-amino groups with slightly higher reactivity under low temperature conditions, achieving selective protection of ε-amino groups, ensuring the stable formation of the regular structure of polyimide, and improving the strength performance of fiber filaments. Tetrahydrofuran can effectively dissolve di-tert-butyl dicarbonate to form a uniform additive solution, ensuring the stability of the reaction.

[0024] 3. Lysine, as a basic material and a bio-based natural material, has a certain degree of degradability. In the pretreatment, the lysine polycondensation reaction catalyzed by Candida antarctica lipase B in 1-ethyl-3-methylimidazolium acetate allows pyromellitic dianhydride to react with p-phenylenediamine to generate a rigid polyimide backbone. The ester bonds of ethyl lactate can be embedded in the backbone, promoting its hydrolytic breakage in a microbial-rich environment. This results in good degradation performance of the fiber filaments in the degradation environment. Attached Figure Description

[0025] Figure 1 The present invention provides a flowchart of a method for preparing and applying bio-based polyimide biodegradable fiber filaments. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0028] Example 1:

[0029] S1: Base material preparation. The raw material for the base material is lysine. After pretreatment, the lysine is used to obtain the base material.

[0030] The pretreatment method for lysine in S1 is as follows: Lysine is mixed with sodium carbonate aqueous solution to obtain a mixture. This mixture, along with 1-ethyl-3-methylimidazolium acetate and Candida antarcticis lipase B, is added to a mixer. The mixer is set to 40 rpm and stirred for 6 minutes. The mixture is then allowed to stand for 10 hours, followed by high-temperature sterilization. The resulting product is added to a reaction vessel. An additive solution is added dropwise to the reaction vessel. After the dropwise addition is complete, the reaction vessel temperature is set to 0°C, the stirring speed is 200 rpm, and the mixture is stirred at a constant temperature for 20 minutes. After the constant-temperature stirring is complete, the mixture is allowed to stand at room temperature for 2 hours. Dilute hydrochloric acid is added to the resulting product to adjust the pH to 2, and the mixture is then allowed to stand at room temperature. The reaction was allowed to stand for 1 hour under warm conditions. The resulting product was filtered to obtain a solid. The solid was washed four times with deionized water and then placed in an oven at 40°C for 4 hours to complete the pretreatment of lysine and obtain the base material. The mass ratio of lysine to sodium carbonate aqueous solution was 1:3, the mass concentration of sodium carbonate aqueous solution was 6%, the mass ratio of the mixed solution, 1-ethyl-3-methylimidazolium acetate, and Candida antarcticis lipase B was 1:0.1:0.06, and the mass of the additive solution was 10% of the mass of the mixed solution. The additive solution was prepared by mixing di-tert-butyl dicarbonate and tetrahydrofuran, with a mass ratio of di-tert-butyl dicarbonate to tetrahydrofuran of 1:4.

[0031] S2: Preparation of the treatment agent. The raw materials for the treatment agent include pyromellitic dianhydride, ethyl lactate, dimethyl isosorbide, p-phenylenediamine, and ethanol. The mass of the treatment agent is 10% of the mass of the base material.

[0032] The treatment agent is prepared as follows: pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide are added to a reaction vessel. Under nitrogen atmosphere, the temperature is set at 120℃, the stirring speed is 200 r / min, and the mixture is stirred at this constant temperature for 4 hours. The resulting product is then added to a mixer, where p-phenylenediamine and ethanol are added. The mixer is stirred at 400 r / min for 40 minutes. The resulting product is then refluxed at 60℃ for 6 hours to obtain the treatment agent. The mass ratio of pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide is 1:0.2:0.03, the mass ratio of p-phenylenediamine and ethanol is 1:3, and the mass of p-phenylenediamine is 20% of the mass of the dianhydride.

[0033] S3: Mixing treatment, the base material and the treatment agent are mixed to obtain coarse material;

[0034] The mixing process is as follows: the base material and the treatment agent are added to a reaction vessel, the reaction vessel is set to a temperature of 50℃, the stirring speed is 200r / min, and the mixture is stirred at a constant temperature for 40min. The resulting product is washed with distilled water 4 times, and then placed in an oven and dried at 50℃ for 4h to obtain a mixture. The mixture, cresol, isoquinoline, and toluene are added to a flask, nitrogen is introduced into the flask to remove air, and the mixture is heated and refluxed at 100℃ for 4h. The water generated in the reaction is removed by a water separator, and then the temperature is raised to 140℃ and the treatment is continued for 8h to complete the mixing process and obtain the crude material.

[0035] S4: Preparation of spinning solution, the raw materials of which include crude material, ethanol and propylene carbonate;

[0036] The method for preparing the spinning solution is as follows: after mixing the crude material and ethanol, the mixture is allowed to stand for 40 minutes. A precipitate is obtained from the product obtained after standing. The process of mixing and standing with ethanol and precipitation is repeated three times. The resulting product is then sent to an oven and dried at 40°C for 6 hours to obtain a dry material. The dry material and propylene carbonate are added to a reaction vessel, which is set to a temperature of 50°C and a stirring speed of 60 r / min. The mixture is stirred at a constant temperature for 2 hours. The resulting product is then filtered and degassed under vacuum to obtain the spinning solution. The mass ratio of crude material to ethanol is 1:3, and the mass ratio of dry material to propylene carbonate is 1:7.

[0037] S5: Spinning and forming process, the spinning solution is subjected to spinning and forming process to obtain fiber filaments;

[0038] The spinning forming process is as follows: the spinning solution is fed into the spinning equipment through a metering pump to complete the spinning forming process and obtain fiber filaments. The spinning equipment is set to a temperature of 280℃, a spinneret diameter of 0.1mm, and a winding speed of 200m / min.

[0039] Example 2:

[0040] S1: Base material preparation. The raw material for the base material is lysine. After pretreatment, the lysine is used to obtain the base material.

[0041] The pretreatment method for lysine in S1 is as follows: Lysine is mixed with an aqueous sodium carbonate solution to obtain a mixture. This mixture, along with 1-ethyl-3-methylimidazolium acetate and Candida antarcticis lipase B, is added to a mixer. The mixer is set to 50 rpm and stirred for 8 minutes. The mixture is then allowed to stand for 15 hours, followed by high-temperature sterilization. The resulting product is added to a reaction vessel, and an additive solution is added dropwise. After the dropwise addition is complete, the reaction vessel is set to 2.5°C, and the stirring speed is 300 rpm. The mixture is stirred at this constant temperature for 25 minutes. After the constant-temperature stirring is complete, the mixture is allowed to stand at room temperature for 3 hours. Dilute hydrochloric acid is added to the resulting product to adjust the pH to 2.5, and the mixture is then allowed to stand at room temperature. The reaction was allowed to stand for 1.5 hours. The resulting product was filtered to obtain a solid. The solid was washed five times with deionized water and then placed in an oven at 50°C for 56 hours to complete the pretreatment of lysine and obtain the base material. The mass ratio of lysine to sodium carbonate aqueous solution was 1:3.5, the mass concentration of sodium carbonate aqueous solution was 7%, the mass ratio of the mixed solution, 1-ethyl-3-methylimidazolium acetate, and Candida antarcticis lipase B was 1:0.15:0.07, and the mass of the additive solution was 15% of the mass of the mixed solution. The additive solution was prepared by mixing di-tert-butyl dicarbonate and tetrahydrofuran, with a mass ratio of di-tert-butyl dicarbonate to tetrahydrofuran of 1:4.5.

[0042] S2: Preparation of the treatment agent. The raw materials for the treatment agent include pyromellitic dianhydride, ethyl lactate, dimethyl isosorbide, p-phenylenediamine, and ethanol. The mass of the treatment agent is 20% of the mass of the base material.

[0043] The treatment agent is prepared as follows: pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide are added to a reaction vessel. Under nitrogen atmosphere, the temperature is set at 130℃, the stirring speed is 300 r / min, and the mixture is stirred at this constant temperature for 5 hours. The resulting product is then added to a mixer, where p-phenylenediamine and ethanol are added. The mixer is stirred at 500 r / min for 50 minutes. The resulting product is then refluxed at 70℃ for 7 hours to obtain the treatment agent. The mass ratio of pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide is 1:0.3:0.04, the mass ratio of p-phenylenediamine and ethanol is 1:4, and the mass of p-phenylenediamine is 25% of the mass of the dianhydride.

[0044] S3: Mixing treatment, the base material and the treatment agent are mixed to obtain coarse material;

[0045] The mixing process is as follows: the base material and the treatment agent are added to a reaction vessel, the reaction vessel is set to a temperature of 55℃, the stirring speed is 300r / min, and the mixture is stirred at a constant temperature for 55min. The resulting product is washed with distilled water 5 times, and then placed in an oven and dried at 60℃ for 5h to obtain a mixture. The mixture, cresol, isoquinoline, and toluene are added to a flask, nitrogen is introduced into the flask to remove air, and the mixture is heated and refluxed at 110℃ for 5h. The water generated in the reaction is removed by a water separator, and then the temperature is raised to 160℃ and the treatment is continued for 9h to complete the mixing process and obtain the crude material.

[0046] S4: Preparation of spinning solution, the raw materials of which include crude material, ethanol and propylene carbonate;

[0047] The method for preparing the spinning solution is as follows: after mixing the crude material and ethanol, the mixture is allowed to stand for 50 min. A precipitate is obtained from the product obtained after standing. The process of mixing and standing with ethanol and precipitation is repeated 4 times. The resulting product is then sent to an oven and dried at 50°C for 7 h to obtain a dry material. The dry material and propylene carbonate are added to a reaction vessel, which is set to a temperature of 55°C and a stirring speed of 80 r / min. The mixture is stirred at a constant temperature for 3 h. The resulting product is then filtered and degassed under vacuum to obtain the spinning solution. The mass ratio of crude material to ethanol is 1:3.5, and the mass ratio of dry material to propylene carbonate is 1:8.

[0048] S5: Spinning and forming process, the spinning solution is subjected to spinning and forming process to obtain fiber filaments;

[0049] The spinning forming process is as follows: the spinning solution is fed into the spinning equipment through a metering pump to complete the spinning forming process and obtain fiber filaments. The spinning equipment is set to a temperature of 300℃, a spinneret diameter of 0.2mm, and a winding speed of 300m / min.

[0050] Example 3:

[0051] S1: Base material preparation. The raw material for the base material is lysine. After pretreatment, the lysine is used to obtain the base material.

[0052] The pretreatment method for lysine in S1 is as follows: Lysine is mixed with sodium carbonate aqueous solution to obtain a mixture. This mixture, along with 1-ethyl-3-methylimidazolium acetate and Candida antarcticis lipase B, is added to a mixer. The mixer is set to 60 rpm and stirred for 10 minutes, followed by a static reaction for 20 hours. Afterward, high-temperature sterilization is performed. The resulting product is added to a reaction vessel, and an additive solution is added dropwise. After the dropwise addition is complete, the reaction vessel is set to 5°C, and the stirring speed is 400 rpm. The mixture is stirred at this constant temperature for 30 minutes. After the constant temperature stirring is complete, the mixture is allowed to stand at room temperature for 4 hours. Dilute hydrochloric acid is added to the resulting product to adjust the pH to 3, and the mixture is then reacted at room temperature. The reaction was allowed to stand for 2 hours under warm conditions. The resulting product was filtered to obtain a solid. The solid was washed 6 times with deionized water and then placed in an oven at 60°C for 6 hours to complete the pretreatment of lysine and obtain the base material. The mass ratio of lysine to sodium carbonate aqueous solution was 1:4, the mass concentration of sodium carbonate aqueous solution was 8%, the mass ratio of the mixed solution, 1-ethyl-3-methylimidazolium acetate, and Candida antarcticis lipase B was 1:0.2:0.08, and the mass of the additive solution was 20% of the mass of the mixed solution. The additive solution was prepared by mixing di-tert-butyl dicarbonate and tetrahydrofuran, with a mass ratio of di-tert-butyl dicarbonate to tetrahydrofuran of 1:5.

[0053] S2: Preparation of the treatment agent. The raw materials for the treatment agent include pyromellitic dianhydride, ethyl lactate, dimethyl isosorbide, p-phenylenediamine, and ethanol. The mass of the treatment agent is 30% of the mass of the base material.

[0054] The treatment agent is prepared as follows: pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide are added to a reaction vessel. Under nitrogen atmosphere, the temperature is set at 140℃, the stirring speed is 400 r / min, and the mixture is stirred at this constant temperature for 6 hours. The resulting product is then added to a mixer, where p-phenylenediamine and ethanol are added. The mixer is stirred at 600 r / min for 60 minutes. The resulting product is then refluxed at 80℃ for 8 hours to obtain the treatment agent. The mass ratio of pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide is 1:0.4:0.05, the mass ratio of p-phenylenediamine and ethanol is 1:5, and the mass of p-phenylenediamine is 30% of the mass of the dianhydride.

[0055] S3: Mixing treatment, the base material and the treatment agent are mixed to obtain coarse material;

[0056] The mixing process is as follows: the base material and the treatment agent are added to a reaction vessel, the reaction vessel is set to a temperature of 60℃, the stirring speed is 400r / min, and the mixture is stirred at a constant temperature for 60min. The resulting product is washed with distilled water 6 times, and then placed in an oven and dried at 70℃ for 6h to obtain a mixture. The mixture, cresol, isoquinoline, and toluene are added to a flask, nitrogen is introduced into the flask to remove air, and the mixture is heated and refluxed at 120℃ for 6h. The water generated in the reaction is removed by a water separator, and then the temperature is raised to 180℃ and the treatment is continued for 10h to complete the mixing process and obtain the crude material.

[0057] S4: Preparation of spinning solution, the raw materials of which include crude material, ethanol and propylene carbonate;

[0058] The method for preparing the spinning solution is as follows: after mixing the crude material and ethanol, the mixture is allowed to stand for 60 min. A precipitate is obtained from the product obtained after standing. The process of mixing and standing with ethanol and precipitation is repeated 5 times. The product is then sent to an oven and dried at 60°C for 8 h to obtain a dry material. The dry material and propylene carbonate are added to a reaction vessel. The reaction vessel is set to a temperature of 60°C and a stirring speed of 100 r / min. The mixture is stirred at a constant temperature for 4 h. The product is then filtered and degassed under vacuum to obtain the spinning solution. The mass ratio of crude material to ethanol is 1:4, and the mass ratio of dry material to propylene carbonate is 1:9.

[0059] S5: Spinning and forming process, the spinning solution is subjected to spinning and forming process to obtain fiber filaments;

[0060] The spinning forming process is as follows: the spinning solution is fed into the spinning equipment through a metering pump to complete the spinning forming process and obtain fiber filaments. The spinning equipment is set to a temperature of 320℃, a spinneret diameter of 0.3mm, and a winding speed of 400m / min.

[0061] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example does not contain any additives.

[0062] Comparative Example 2 differs from Example 1 in that it does not contain 1-ethyl-3-methylimidazolium acetate.

[0063] Comparative Example 3 differs from Example 1 in that it does not contain Candida antarctica lipase B.

[0064] Comparative Example 4 differs from Example 1 in that lysine was not pretreated in this comparative example.

[0065] Performance testing: The fiber filaments prepared in Examples 1, 2, 3, 1, 2, 3, and 4 were subjected to performance tests, and the test data are recorded in the table below:

[0066]

[0067]

[0068] In the performance test, the test methods in GB / T 14344-2008 were used to test the breaking elongation and breaking strength of the fiber filaments prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 respectively.

[0069] The soil degradation rate was tested as follows: 100 mg of the fiber filaments prepared in Examples 1, 2, 3, 1 Comparative Example 1, 2 Comparative Example 2, 3 Comparative Example 3 and 4 were weighed and buried in 500 g of soil. The soil pH was 7.0, the water content was 25%, the temperature was 30℃, and the burial time was 1 year. During the burial process, 10 mL of 1% glucose solution was added to the soil every 15 days. After the time was over, the mass loss rate of the fiber filaments was measured to obtain the degradation rate data.

[0070] It is evident that the elongation at break and tensile strength of the fiber filaments prepared in Comparative Examples 1, 2, 3, and 4 are all lower than those in Examples 1, 2, and 3. This indicates that in the preparation of fiber filaments, the pretreatment of lysine, specifically the alkaline treatment of lysine with sodium carbonate aqueous solution, can deprotonate the lysine carboxyl group to form a carboxylate ion, increasing water solubility. 1-ethyl-3-methylimidazolium acetate can swell lysine, enhancing its catalytic activity. Candida antarcticis lipase B can catalyze the formation of an amide bond between the carboxyl and amino groups of lysine, thereby generating lysine-based oligoamides and forming a regular molecular chain structure. This regular structure generated after pretreatment can serve as a support in subsequent polymerization processes, facilitating the stable formation of the fiber filament structure and improving the strength properties of the fiber filament.

[0071] Di-tert-butyl dicarbonate can react with the slightly more reactive ε-amino group under low temperature conditions, achieving selective protection of the ε-amino group, ensuring the stable formation of the regular structure of polyimide, and improving the strength of the fiber filament. Tetrahydrofuran can effectively dissolve di-tert-butyl dicarbonate to form a uniform additive solution, ensuring the stability of the reaction.

[0072] Lysine, as a basic material and a bio-based natural material, has a certain degree of degradability. In the pretreatment, the lysine polycondensation reaction catalyzed by Candida antarctica lipase B in 1-ethyl-3-methylimidazolium acetate allows pyromellitic dianhydride to react with p-phenylenediamine to generate a rigid polyimide backbone. The ester bonds of ethyl lactate can be embedded in the backbone, promoting its hydrolytic breakage in a microbial-rich environment. This results in good degradation performance of the fiber filaments in the degradation environment.

[0073] By comparing and analyzing the relevant data in the table, it can be seen that the fiber filaments prepared by this invention not only have good elongation at break but also excellent tensile strength. This indicates that the bio-based polyimide biodegradable fiber filaments provided by this invention have a broader market prospect and are more suitable for widespread application.

[0074] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0075] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing bio-based polyimide biodegradable fiber filaments, characterized in that: Includes the following steps: S1: Base material preparation. The raw material for the base material is lysine. After pretreatment, the lysine is used to obtain the base material. S2: Preparation of the treatment agent. The raw materials for the treatment agent include pyromellitic dianhydride, ethyl lactate, dimethyl isosorbide, p-phenylenediamine, and ethanol. The mass of the treatment agent is 10-30% of the mass of the base material. S3: Mixing treatment, the base material and the treatment agent are mixed to obtain coarse material; S4: Preparation of spinning solution, the raw materials of which include crude material, ethanol and propylene carbonate; S5: Spinning forming process, the spinning solution is used for spinning forming process to obtain fiber filaments.

2. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 1, characterized in that, The pretreatment method for lysine in S1 is as follows: Lysine is mixed with an aqueous sodium carbonate solution to obtain a mixture. This mixture, along with 1-ethyl-3-methylimidazolium acetate and Candida antarcticis lipase B, is added to a mixer. The mixer is set to 40-60 r / min and stirred for 6-10 min. The mixture is then allowed to stand for 10-20 h, followed by high-temperature sterilization. The resulting product is added to a reaction vessel. An additive solution is then added dropwise to the reaction vessel. After the dropwise addition is complete, the reaction vessel temperature is set to 0-5℃, and the stirring is continued. The stirring speed is 200-400 r / min, and the mixture is stirred at a constant temperature for 20-30 min. After the stirring is completed, the mixture is allowed to stand at room temperature for 2-4 h. Dilute hydrochloric acid is added to the product to adjust the pH to 2-3, and the mixture is allowed to stand at room temperature for 1-2 h. The product is then filtered to obtain a solid. The solid is washed with deionized water 4-6 times and then placed in an oven at 40-60℃ for 4-6 h to complete the pretreatment of lysine and obtain the base material.

3. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 2, characterized in that, The mass ratio of lysine to sodium carbonate aqueous solution is 1:(3-4), the mass concentration of sodium carbonate aqueous solution is 6-8%, the mass ratio of the mixture, 1-ethyl-3-methylimidazolium acetate, and Candida antarcticis lipase B is 1:(0.1-0.2):(0.06-0.08), and the mass of the added solution is 10-20% of the mass of the mixture.

4. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 2, characterized in that, The additive solution is prepared by mixing di-tert-butyl dicarbonate and tetrahydrofuran, with a mass ratio of di-tert-butyl dicarbonate to tetrahydrofuran of 1:(4-5).

5. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 1, characterized in that, The method for preparing the treatment agent is as follows: pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide are added to a reaction vessel. Under nitrogen atmosphere, the temperature is set at 120–140°C, the stirring speed is 200–400 r / min, and the mixture is stirred at this constant temperature for 4–6 hours. The resulting product is then added to a mixer, where p-phenylenediamine and ethanol are added. The mixer is set to 400–600 r / min and stirred for 40–60 minutes. The resulting product is then refluxed at 60–80°C for 6–8 hours to obtain the treatment agent. The mass ratio of pyromellitic dianhydride, ethyl lactate, and dimethyl isosorbide is 1:(0.2–0.4):(0.03–0.05), and the mass ratio of p-phenylenediamine and ethanol is 1:(3–5). The mass of p-phenylenediamine is 20–30% of the mass of the dianhydride.

6. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 1, characterized in that, The mixing process is as follows: the base material and the treatment agent are added to a reaction vessel, the reaction vessel is set to a temperature of 50-60℃, the stirring speed is 200-400 r / min, and the mixture is stirred at a constant temperature for 40-60 min. The resulting product is washed with distilled water 4-6 times, and then placed in an oven and dried at 50-70℃ for 4-6 h to obtain a mixture. The mixture, cresol, isoquinoline, and toluene are added to a flask, nitrogen is introduced into the flask to remove air, and the mixture is heated under reflux at 100-120℃ for 4-6 h. The water generated in the reaction is removed by a water separator, and then the temperature is raised to 140-180℃ and the treatment continues for 8-10 h to complete the mixing process and obtain the crude material.

7. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 1, characterized in that, The method for preparing the spinning solution is as follows: after mixing the crude material and ethanol, let it stand for 40-60 minutes. A precipitate is obtained from the product obtained after standing. The process of mixing and standing with ethanol and precipitation is repeated 3-5 times. The product is then sent to an oven and dried at 40-60°C for 6-8 hours to obtain a dry material. The dry material and propylene carbonate are then added to a reaction vessel. The reaction vessel is set to a temperature of 50-60°C and a stirring speed of 60-100 r / min. The mixture is stirred at a constant temperature for 2-4 hours. The product is then filtered and degassed under vacuum to obtain the spinning solution.

8. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 7, characterized in that, The mass ratio of crude material to ethanol is 1:(3-4), and the mass ratio of dry material to propylene carbonate is 1:(7-9).

9. The method for preparing bio-based polyimide biodegradable fiber filaments according to claim 1, characterized in that, The spinning forming process is as follows: the spinning solution is fed into the spinning equipment through a metering pump to complete the spinning forming process and obtain fiber filaments. The spinning equipment is set to a temperature of 280-320℃, a spinneret diameter of 0.1-0.3mm, and a winding speed of 200-400m / min.

10. The application of a fiber filament prepared by the method for preparing bio-based polyimide biodegradable fiber filaments according to claims 1-9, characterized in that, The fiber filaments are used in fabrics and composite materials.

Images