Polyimide fiber and its preparation method and application
By performing aging treatment during the preparation of polyimide fibers, the residual stress inside the fiber is eliminated, and the problem of poor mechanical stability of polyimide fibers is solved, which significantly improves its durability and stability.
Patent Information
- Application Number
- CN202411865290.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2025-04-08
AI Technical Summary
The polyimide fibers prepared by the existing methods have poor mechanical stability, which affects their strength, durability and dimensional stability.
By preparing a polyamic acid slurry by diamine monomer, dianhydride monomer and organic solvent, and spinning imidation treatment is performed to obtain the initial product of polyimide fibers, and aging treatment is performed to eliminate internal residual stress.
Effectively improve the problem that the strength of the finished polyimide fibers will drop sharply over time, greatly improve the durability of its mechanical properties, and improve the mechanical stability, dimensional stability and strength stability.
Smart Images
Figure CN119777020A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of polymer technology, and in particular to a polyimide fiber and a preparation method and application thereof. Background Art
[0002] Polyimide fiber material is a new type of special fiber with excellent comprehensive performance. It contains imide rings in the molecular chain and has many excellent properties such as high strength, high modulus, high temperature resistance, flame retardancy, chemical corrosion resistance, low temperature resistance, etc. It is widely used in high-tech fields such as aerospace, weapons and equipment, and transportation. At present, the preparation process of polyimide fiber mainly includes wet spinning process. In the process of wet spinning to produce high-strength polyimide fiber, the polyamide acid slurry is ejected from the spinneret to form primary fiber in the coagulation bath. After washing and drying, it enters the high-temperature drying tunnel and forms polyimide fiber with certain tensile strength through thermal imidization dehydration closed loop under tension.
[0003] At present, the mechanical stability of the prepared polyimide fiber is poor, which will weaken the strength and durability of the polyimide fiber to a certain extent, and will also affect the dimensional stability of the polyimide fiber, thereby affecting the service life and application of the polyimide fiber. Summary of the invention
[0004] The purpose of the present application is to provide a polyimide fiber and a preparation method and application thereof, aiming to solve to a certain extent the problem that the mechanical stability of the polyimide fiber prepared by the existing method is poor, which affects its strength, durability and dimensional stability.
[0005] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:
[0006] In a first aspect, the present application provides a method for preparing a polyimide fiber, comprising the following steps:
[0007] Prepare polyamic acid slurry by using diamine monomer, dianhydride monomer and organic solvent;
[0008] The polyamic acid slurry is subjected to spinning imidization treatment to obtain a primary polyimide fiber product;
[0009] The polyimide fiber primary product is subjected to aging treatment to obtain the polyimide fiber.
[0010] In a second aspect, the present application provides a polyimide fiber, which is prepared by the above method.
[0011] In a third aspect, the present application provides an application of a polyimide fiber, wherein the polyimide fiber prepared by the above method, or the above polyimide fiber is applied to at least one field of aerospace, electronics industry, automobile industry, protective products, and shipbuilding.
[0012] The preparation method of the polyimide fiber provided in the first aspect of the present application, after diamine monomer, dianhydride monomer and organic solvent are made into polyamic acid slurry, spinning imidization treatment is carried out to obtain the polyimide fiber primary product. Then, the polyimide fiber primary product is subjected to aging treatment, and the polyimide fiber obtained by spinning eliminates the residual stress inside it after aging treatment, which can effectively improve the problem that the strength of the polyimide fiber finished product drops sharply over time, greatly improve the durability of the mechanical properties of the polyimide fiber, thereby improving the mechanical stability, dimensional stability, strength stability and other characteristics of the polyimide fiber, and improving its application stability and service life. The purpose of maintaining the long-term stability of the tensile strength of the polyimide fiber is achieved by the aging treatment method, and the method has the advantages of low cost, easy operation, simple process, etc., and is particularly suitable for the industrial production of polyimide fibers.
[0013] The polyimide fiber provided in the second aspect of the present application is prepared by the above method. The internal residual stress of the polyimide fiber is low, and the degradation of the tensile strength of the polyimide fiber over time is small (within 5%), thereby achieving the purpose of maintaining the long-term stability of the mechanical properties of the polyimide fiber and greatly improving the durability of the mechanical properties of the polyimide fiber.
[0014] The above-mentioned polyimide fiber of the present application has high tensile strength, high modulus, and a small degree of degradation over time. The polyimide fiber has stable mechanical properties and high durability, and can be widely used in aerospace, electronics industry, automobile industry, protective products, shipbuilding and other fields. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0016] Figure 1 It is a schematic diagram of a process for preparing a polyimide fiber provided in an embodiment of the present application;
[0017] Figure 2 It is a schematic flow chart of the method for preparing polyimide fiber provided in Example 1 of the present application. DETAILED DESCRIPTION
[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0019] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.
[0020] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.
[0021] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.
[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.
[0023] The weight of the relevant components mentioned in the embodiments of the present specification can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components in the embodiments of the present specification is proportionally enlarged or reduced, it is within the scope disclosed in the embodiments of the present specification. Specifically, the mass described in the embodiments of the present specification can be μg, mg, g, kg and other mass units known in the chemical industry.
[0024] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.
[0025] The first aspect of the present application provides a method for preparing a polyimide fiber, as shown in the attached Figure 1 As shown, the following steps are included:
[0026] S10. The diamine monomer, the dianhydride monomer and the organic solvent are prepared into a polyamic acid slurry;
[0027] S20. The polyamic acid slurry is subjected to spinning imidization treatment to obtain a polyimide fiber primary product;
[0028] S30. Performing aging treatment on the initial product of polyimide fiber to obtain polyimide fiber.
[0029] The preparation method of the polyimide fiber provided in the first aspect of the embodiment of the present application, after diamine monomer, dianhydride monomer and organic solvent are made into polyamic acid slurry, spinning imidization treatment is carried out to obtain the polyimide fiber primary product. Then, the polyimide fiber primary product is subjected to aging treatment, and the polyimide fiber obtained by spinning eliminates the residual stress inside it after aging treatment, which can effectively improve the problem that the strength of the polyimide fiber finished product drops sharply over time, greatly improve the durability of the mechanical properties of the polyimide fiber, thereby improving the mechanical stability, dimensional stability, strength stability and other characteristics of the polyimide fiber, and improving its application stability and service life. The purpose of maintaining the long-term stability of the tensile strength of the polyimide fiber is achieved by the aging treatment method, and the method has the advantages of low cost, easy operation, simple process, etc., and is particularly suitable for the industrial production of polyimide fibers.
[0030] The polyimide fiber of the present application embodiment is subjected to tension stretching and high temperature during the preparation and formation process such as spinning, and the polymer chains of different molecular weights inside the fiber are affected inconsistently, resulting in a large amount of residual stress inside the fiber. The existence of residual stress seriously affects the stability of the mechanical properties of the polyimide fiber, not only weakens the strength and durability of the polyimide fiber, but also affects the dimensional stability of the high-strength polyimide fiber, and even causes serious deformation. When the residual stress exceeds the strength limit of the polyimide fiber, cracks or breaks will occur on the fiber surface, resulting in a significant decrease in the tensile strength of the finished fiber bundle. Among them, residual stress refers to the self-balanced internal stress that remains in the object after the action of external force or uneven temperature field. Both mechanical processing and strengthening processes can cause residual stress. Residual stress is generally harmful. When the total amount of residual stress exceeds the strength limit of the object, it will cause the object to crack or break. The residual stress of the object can be eliminated by appropriate heat treatment and other methods. After the aging treatment, the internal residual stress of the polyimide fiber in the embodiment of the present application is eliminated, which can effectively improve the problem of the sudden drop in strength of the finished polyimide fiber over time and greatly improve the durability of the mechanical properties of the polyimide fiber.
[0031] In the above step S10:
[0032] In some possible implementations, the diamine monomer includes at least one of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-diaminobenzanilide (DABA), 2-(4-aminophenyl)-5-aminobenzimidazole (R3), and 2-(4-aminophenyl)-5-aminobenzoxazole (APBOA). These diamine monomers can be polymerized with dianhydride monomers to generate polyimide fibers.
[0033] In some possible implementations, the diamine monomer includes at least two of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-diaminobenzanilide (DABA), 2-(4-aminophenyl)-5-aminobenzimidazole (R3), and 2-(4-aminophenyl)-5-aminobenzoxazole (APBOA). In this case, the polyimide fiber is prepared by two diamine monomers to form hydrogen bonds between polymer chains, which can better provide the tensile strength of the polyimide fiber.
[0034] In some possible implementations, the dianhydride monomer includes at least one of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-biphenyl ether dianhydride (ODPA), and bisphenol A diether dianhydride (BPADA); these dianhydride monomers can be polymerized with diamine monomers to form polyimide fibers.
[0035] In some possible implementations, the molar ratio of the diamine monomer to the dianhydride monomer is (0.95-1.05): 1. Exemplarily, the molar ratio of the diamine monomer to the dianhydride monomer can be 0.95: 1, 0.96: 1, 0.97: 1, 0.98: 1, 0.99: 1, 1.0: 1, 1.05: 1, and other typical but non-limiting arbitrary point values or interval values between any two point values. In this case, considering the viscosity of the polyamic acid, the viscosity of the polyamic acid slurry can be effectively controlled by adjusting the molar ratio between the two types of monomers, diamine and dianhydride, so that it is convenient to produce polyimide fibers through processes such as spinning. Usually, when the molar ratio between the two monomers is within ± 5%, a polyamic acid slurry with suitable viscosity can be obtained to ensure the performance of the polyimide fiber. Otherwise, the slurry viscosity will be too low or too high, which is not conducive to the industrial preparation of polyimide.
[0036] In some possible implementations, the organic solvent includes at least one of N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), γ-butyrolactone (GBL), and cyclohexanone (CHO). These organic solvents have a good dissolving effect on diamine monomers and dianhydride monomers, which is conducive to the polymerization of diamine monomers and dianhydride monomers to form polyamic acid slurry.
[0037] In some possible implementations, the moisture content in the organic solvent is not higher than 300ppm. Exemplary, the moisture content in the organic solvent is lower than 300ppm, preferably lower than 200ppm, further preferably lower than 100ppm, further preferably lower than 50ppm, etc. In this case, the water content of the organic solvent is low, which is conducive to improving the stability of the diamine monomer and the dianhydride monomer, thereby ensuring that the diamine monomer and the dianhydride monomer react to generate polyamic acid slurry. When the organic solvent water content is too high, the dianhydride monomer will deteriorate after contacting moisture, thereby reducing the efficiency of the polymerization reaction to generate qualified polyamic acid slurry.
[0038] In some possible implementations, the preparation steps of the polyamic acid slurry include: dissolving the diamine monomer in an organic solvent under an inert atmosphere at a temperature of 40°C to 50°C, adding a dianhydride monomer after cooling to 1°C to 10°C for mixing, and obtaining a polyamic acid slurry. In this case, the diamine monomer is added at a higher temperature to allow the diamine monomer to be evenly dispersed in the solvent and to improve the uniformity of the diamine monomer dispersion. In addition, the addition of dianhydride at a lower temperature is to increase the polymerization reaction limit. The polymerization reaction of the diamine monomer and the dianhydride monomer to obtain polyamic acid is a reversible reaction, and the balance of the reversible reaction is significantly affected by temperature. Too high a temperature will cause the reaction balance to move in the direction of breaking the polyamic acid molecular chain and decreasing the degree of polymerization, resulting in too low a molecular weight and too low a viscosity to obtain a qualified polyamic acid slurry.
[0039] In some embodiments, the temperature is 40°C to 50°C in an inert atmosphere, which may be nitrogen, argon, helium, etc. The temperature may be any typical but non-limiting point value such as 40°C, 45°C, 50°C, or an interval value between any two points.
[0040] In some embodiments, the cooling temperature can be any typical but non-limiting point value such as 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, etc., or an interval value between any two points.
[0041] In some embodiments, the mixing processing duration may be any typical but non-limiting point value such as 10 h, 12 h, 15 h, 18 h, 20 h, 24 h, or an interval value between any two point values.
[0042] In some possible implementations, the viscosity of the polyamic acid slurry is 30000cps to 300000cps. Exemplarily, the viscosity of the polyamic acid slurry can be 30000cps, 50000cps, 80000cps, 100000cps, 150000cps, 200000cps, 250000cps, 300000cps, and other typical but non-limiting arbitrary point values or interval values between any two point values. When the viscosity of the polyamic acid slurry is lower than this viscosity range, the dianhydride monomer can be added in batches to increase its viscosity. When the viscosity of the polyamic acid slurry is higher than this viscosity range, it can be diluted by adding a solvent to reduce its viscosity. The added solvent can be the same solvent used for the polymerization reaction, or it can be other solvents. The polyimide fiber production equipment and process have certain requirements for the viscosity of the polyamic acid slurry. Controlling the viscosity of the polyamic acid within this range is more conducive to the production of polyimide fiber products. When the viscosity is too low, the polyamic acid slurry is difficult to form into polyamic acid fibers. When the viscosity is too high, it will affect the spinning process and cause damage to the spinneret, etc.
[0043] In the above step S20: the polyamic acid slurry is subjected to spinning imidization treatment, and the polyamic acid slurry is sprayed out from the spinneret to form primary fibers in the coagulation bath, and then enters the high-temperature drying tunnel after washing and drying. Under tension stretching, the polyamic acid is dehydrated and closed-looped through thermal imidization to form polyimide fibers with a certain tensile strength.
[0044] In some embodiments, the spinning method of polyamic acid slurry includes wet spinning, electrostatic spinning, dry spinning, dry-wet blending, etc., which is widely practical and can be flexibly selected according to actual application requirements. Among them, wet spinning is to prepare polyamic acid slurry as spinning solution, and the spinning solution is sent to the spinning machine, measured by a metering pump, and then enters the spinneret through a candle filter and a connecting tube. The stock solution stream pressed out from the spinneret hole enters the coagulation bath, the solvent in the stock solution stream diffuses into the coagulation bath, and the coagulant penetrates into the stream, so that the stock solution stream reaches a critical concentration, and precipitates in the coagulation bath to form a fiber. Electrostatic spinning is a technology that uses electrostatic force to extract a polymer solution or a molten polymer beam in a liquid into a fiber. The polyamic acid slurry is ejected through a fine-pore spray head using a high-voltage electric field, so that the ejected liquid forms a thin stream, and an electrostatic field is generated near the spray head, so that the polymer ions or molecules in the stream are charged, and then accelerated by the action of the electric field force. When the polymer in the flow tends to have a positive charge, it will be repelled by the charge, forming fine and evenly dispersed fibers, and finally the fibers are fixed by heating or airflow in the direction of the jet. Dry spinning is to spray the polyamide acid slurry through the spinneret. In the air behind the spinneret, the solvent evaporates rapidly, and the polymer undergoes a phase change during the volatilization process, from liquid to solid. At the same time, the fiber is also stretched and refined to a certain extent. Dry-wet blending is a spinning technology that combines "dry spinning" with "wet spinning", also known as dry-wet spinning or dry-wet spinning. The polyamide acid slurry is strongly transported from the spinning barrel to the spinneret after filtration and degassing. The solution stream is ejected vertically downward from the spinneret, first passing through a gas (air or inert gas) layer with a height of about several centimeters to more than ten centimeters, and then entering the coagulation bath. The filaments are wound into a tube after desolventization and curing.
[0045] In some possible implementations, the step of spinning imidization treatment includes: extruding the polyamic acid slurry according to the linear density specification of 1000 dtex to 2000 dtex at a spinning speed of 15 m / min to 25 m / min through spinning metering, and dehydrating and ring-closing the polyamic acid at a temperature of 400°C to 600°C to obtain a polyimide fiber primary product. The reaction of converting polyamic acid into polyimide in the embodiment of the present application is completed simultaneously under the high temperature conditions of the spinning process. Under the high temperature conditions of spinning (usually a temperature above 400°C), the polyamic acid undergoes a dehydration and ring-closing reaction to convert the polyamic acid fiber into a polyimide fiber.
[0046] Exemplarily, the linear density of the imidization treatment can be 1000dtex, 1200dtex, 1500dtex, 1800dtex, 2000dtex, etc., typical but non-limiting arbitrary point values or interval values between any two point values; the spinning speed can be 15m / min, 18m / min, 20m / min, 21m / min, 23m / min, 25m / min, etc., typical but non-limiting arbitrary point values or interval values between any two point values; the temperature can be 400°C, 450°C, 500°C, 550°C, 600°C, etc., typical but non-limiting arbitrary point values or interval values between any two point values.
[0047] In the above step S30:
[0048] In some possible implementations, the temperature condition of the aging treatment is 50°C to 150°C, and the duration is 10min to 12h. In this case, the residual stress in the initial product of the polyimide fiber can be fully eliminated, the problem of the sudden drop in the strength of the finished polyimide fiber over time can be effectively improved, and the durability of the mechanical properties of the polyimide fiber can be greatly improved. Exemplarily, the temperature of the aging treatment can be 50°C, 60°C, 80°C, 100°C, 120°C, 150°C, etc., typical but non-restrictive arbitrary point values or interval values between any two point values, and the duration can be 10min, 30min, 60min, 1h, 2h, 5h, 8h, 10h, 12h, etc., typical but non-restrictive arbitrary point values or interval values between any two point values.
[0049] During the transportation and storage of the polyimide fiber in the embodiment of the present application, the temperature of the environment in which the polyimide fiber is located may be close to 50°C. If the aging treatment temperature is lower than 50°C, it will be close to the storage and transportation environment. The problem addressed by the embodiment of the present application is that the tensile strength of the polyimide fiber will decrease in the storage and transportation environment. Therefore, when the aging treatment temperature is lower than 50°C, the effect of eliminating the residual stress of the polyimide fiber by aging treatment is limited. If the aging treatment temperature is too high, a certain degree of interaction will occur within and between the molecular chains of the polyimide fiber, thereby affecting the tensile strength and other properties of the polyimide fiber.
[0050] In addition, the duration of the aging treatment ensures that the residual stress in the polyimide fiber is fully eliminated. If the aging treatment time is too short, it will affect the elimination of the residual stress in the polyimide fiber. If the aging treatment time is too long, it will lead to energy waste. Moreover, the duration of the aging treatment is closely related to the temperature of the aging treatment. Generally, the higher the temperature, the shorter the time, and the lower the temperature, the longer the time. In some embodiments, when the internal residual stress of the polyimide fiber is eliminated by aging treatment, the treatment effect of 50°C and 12h is equivalent to the treatment effect of 100°C, 2h and 150°C, 10min. In actual application, different aging treatment methods can be selected for different application scenarios. For example, high temperature and short time can be used in the laboratory, which is fast and efficient, while low temperature and long time can be used in large-scale industrial production, with high safety factor and low energy consumption.
[0051] In a second aspect, an embodiment of the present application provides a polyimide fiber, which is prepared by the above method.
[0052] The polyimide fiber of the embodiment of the present application is prepared by the above method. The internal residual stress of the polyimide fiber is low, and the degradation of the tensile strength of the polyimide fiber over time is small (within 5%), thereby achieving the purpose of maintaining the long-term stability of the mechanical properties of the polyimide fiber and greatly improving the durability of the mechanical properties of the polyimide fiber.
[0053] In some possible implementations, the tensile strength of the polyimide fiber after storage for 12 months is ≥ 27 cN / dtex. The polyimide fiber has high tensile strength, and the degradation over time is small, and the mechanical properties of the polyimide fiber are stable. Among them, cN / dtex represents the centinewon (cN) force that each dtex (dtex) fiber can withstand. Exemplarily, the tensile strength of the polyimide fiber after storage for 12 months can be 27 cN / dtex, 27.1 cN / dtex, 27.27 cN / dtex, 27.35 cN / dtex, 27.54 cN / dtex, 27.64 cN / dtex, 27.81 cN / dtex, 27.87 cN / dtex, 28 cN / dtex, 28.11 cN / dtex, 28.19 cN / dtex, 28.3 cN / dtex, 28.4 cN / dtex, 28.5 cN / dtex, 28.6 cN / dtex, 28.66 cN / dtex, 28.8 cN / dtex, 30 cN / dtex, or the like, or an interval value between any two points.
[0054] In some possible implementations, the modulus of the polyimide fiber after storage for 12 months is ≥810cN / dtex. Fiber modulus refers to the stiffness exhibited by the fiber material during stretching, that is, the rate of change of unit stress under unit strain, and is an important indicator for describing the elastic capacity of the fiber material. The high modulus of polyimide fiber means that the fiber deforms less when subjected to force, can maintain good shape stability, and is not easily deformed. This characteristic makes high modulus polyimide fiber have excellent mechanical properties and stability, can withstand large external forces without being easily deformed, and thus performs well in various applications.
[0055] Exemplarily, the modulus of the polyimide fiber after storage for 12 months can be 810cN / dtex, 820cN / dtex, 830cN / dtex, 840cN / dtex, 850cN / dtex, 860cN / dtex, 880cN / dtex, 900cN / dtex, 910cN / dtex, 920cN / dtex, 930cN / dtex, 940cN / dtex, 950cN / dtex, 100cN / dtex, or the like, any typical but non-limiting point value or an interval value between any two point values.
[0056] In a third aspect, an embodiment of the present application provides an application of a polyimide fiber, wherein the polyimide fiber prepared by the above method, or the above polyimide fiber is applied to at least one field of aerospace, electronics industry, automobile industry, protective products, and shipbuilding.
[0057] The polyimide fiber in the above-mentioned embodiment of the present application has high tensile strength, high modulus, and a small degree of degradation over time. The polyimide fiber has stable mechanical properties and high durability, and can be widely used in aerospace, electronics industry, automobile industry, protective products, shipbuilding and other fields.
[0058] In the fields of aerospace, automobile manufacturing, electronics industry, protective products, shipbuilding, etc., high modulus and high tensile strength polyimide fibers can be used as reinforcing materials to significantly improve the strength and stiffness of structural parts. For example, in aircraft manufacturing, high modulus and high tensile strength polyimide fibers can be used to strengthen key parts such as wings and fuselages to improve the strength and durability of the overall structure. In the automotive industry, automotive parts made of high modulus and high tensile strength polyimide fibers, such as body structures and seat frames, can significantly improve the impact resistance and corrosion resistance of automobiles. In addition, high modulus and high tensile strength polyimide fibers have the characteristics of light weight, so they can effectively reduce the weight of the overall structure when used. In the field of aerospace, reducing weight means reducing fuel consumption and improving flight efficiency; in the automotive industry, reducing weight can improve fuel economy and reduce operating costs. In addition, high modulus and high tensile strength polyimide fibers usually have good corrosion resistance and fatigue resistance, and can maintain stable performance in extreme environments. This characteristic makes high modulus fiber have broad application prospects in harsh environments such as chemical industry and ocean.
[0059] In order to enable those skilled in the art to clearly understand the implementation details and operations of the present application, and to demonstrate the significant improvement in the performance of the polyimide fiber and the preparation method thereof in the embodiments of the present application, the above technical solution is illustrated by multiple embodiments below.
[0060] Example 1
[0061] A polyimide fiber, such as Figure 2 As shown, its preparation comprises the steps of:
[0062] S1: Add 40.00 kg of NMP solvent into a dry and clean 50 L reactor;
[0063] S2: 45°C circulating warm water is introduced into the jacket of the reactor, and the solvent water bath is heated until the temperature sensor in the reactor shows a stable reading;
[0064] S3: Take NMP sample to test its moisture content, repeat the test 3 times, take the average of the 3 test results, the average is 114.836ppm;
[0065] S4: After the temperature in the reactor is stable, 1527.29 g of diamine monomer R3 and 245.49 g of diamine monomer p-PDA are added into the reactor at one time, and stirred until the diamine monomer is evenly dispersed in the solvent;
[0066] S5: After the diamine monomer is evenly dispersed in the solvent, the warm water in the jacket of the reactor is discharged and circulating cooling water with a temperature of 5° C. is filled in to cool the diamine monomer solution;
[0067] S6: After the diamine monomer solution is cooled, 2671.66 g of dianhydride monomer BPDA is added to the reactor and stirred for 12 hours;
[0068] S7: The diamine monomer and the dianhydride monomer undergo polymerization reaction to generate polyamic acid slurry. The dynamic viscosity of the slurry sampled and tested is 113527 cps.
[0069] S8: transferring the polyamic acid slurry into a storage tank for wet spinning to prepare a polyimide fiber primary product;
[0070] S9: The polyimide fiber primary product is rolled up according to the weight of each roll of 100.00±10g, and 5 rolls of samples are taken to test their mechanical properties respectively, and each roll is tested 5 times;
[0071] S10: Take 5 rolls of finished polyimide fiber primary product and bake them in a constant temperature oven at 50° C. for 12 hours. After baking, store the samples in an indoor environment to obtain polyimide fiber.
[0072] Example 2
[0073] A polyimide fiber, which differs from Example 1 in that: S10: taking 5 rolls of finished polyimide fiber primary product and baking them continuously in a constant temperature oven at 100° C. for 2 hours, and after baking, storing the samples in an indoor environment to obtain polyimide fiber.
[0074] Example 3
[0075] A polyimide fiber, which differs from Example 1 in that: S10: taking 5 rolls of finished polyimide fiber primary product and baking them continuously in a constant temperature oven at 150° C. for 10 minutes, and after baking, storing the samples in an indoor environment to obtain polyimide fiber.
[0076] Example 4
[0077] A polyimide fiber, which differs from Example 1 in that: S10: taking 5 rolls of finished polyimide fiber primary product and baking them continuously in a constant temperature oven at 25° C. for 24 hours, and after baking, storing the samples in an indoor environment to obtain polyimide fiber.
[0078] Example 5
[0079] A polyimide fiber, which differs from Example 1 in that: S10: taking 5 rolls of finished polyimide fiber primary product and baking them continuously in a constant temperature oven at 200° C. for 5 minutes, and after baking, storing the samples in an indoor environment to obtain polyimide fiber.
[0080] Example 6
[0081] A polyimide fiber, such as Figure 2As shown, its preparation comprises the steps of:
[0082] S1: Add 40.00 kg of NMP solvent into a dry and clean 50 L reactor;
[0083] S2: 45°C circulating warm water is introduced into the jacket of the reactor, and the solvent water bath is heated until the temperature sensor in the reactor shows a stable reading;
[0084] S3: Take an NMP sample and test its moisture content. Repeat the test 3 times and take the average of the 3 test results. The average is 153.826ppm.
[0085] S4: After the temperature in the reactor is stable, 1922.37 g of diamine monomer R3 is added into the reactor at one time, and the mixture is stirred until the diamine monomer is evenly dispersed in the solvent;
[0086] S5: After the diamine monomer is evenly dispersed in the solvent, the warm water in the jacket of the reactor is discharged and circulating cooling water with a temperature of 5° C. is filled in to cool the diamine monomer solution;
[0087] S6: After the diamine monomer solution is cooled, 2522.07 g of dianhydride monomer BPDA is added to the reactor and stirred for 12 hours;
[0088] S7: The diamine monomer and the dianhydride monomer undergo polymerization reaction to generate polyamic acid slurry. The dynamic viscosity of the slurry is 76884 cps after sampling and testing.
[0089] S8: transferring the polyamic acid slurry into a storage tank for wet spinning to prepare a polyimide fiber primary product;
[0090] S9: The polyimide fiber primary product is rolled up according to the weight of each roll of 100.00±10g, and 5 rolls of samples are taken to test their mechanical properties respectively, and each roll is tested 5 times;
[0091] S10: Take 5 rolls of finished polyimide fiber primary product and bake them in a constant temperature oven at 50° C. for 12 hours. After baking, store the samples in an indoor environment to obtain polyimide fiber.
[0092] Comparative Example 1
[0093] A polyimide fiber, which differs from Example 1 in that: S10: taking 5 rolls of finished polyimide fiber initial products without aging, storing them in an indoor environment, and obtaining polyimide fibers.
[0094] In order to verify the progressiveness of the embodiments of the present application, the mechanical properties of the polyimide fiber preliminary product prepared in the above-mentioned embodiment 1 were tested, and the polyimide fibers prepared in embodiments 1 to 6 and comparative example 1 were sampled and tested in accordance with GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments" when the storage time was 0 day, 15 days, 1 month, 3 months, 6 months, and 12 months, and the data of tensile strength, modulus, and elongation were collected.
[0095] The above test results are shown in Tables 1 and 2 below:
[0096] Table 1 Mechanical properties
[0097]
[0098] Table 2 The decrease of tensile strength of polyimide fiber over time
[0099]
[0100] It can be seen from the above results that the polyimide fiber of the embodiment of the present application eliminates the residual stress inside it through aging treatment, and effectively improves the problem of sudden drop in strength of the finished polyimide fiber over time. Due to the low aging treatment temperature in Example 4 and the high aging treatment temperature in Example 5, the effect of eliminating the residual stress inside the polyimide fiber is significantly lower than that of Example 1-Example 3 and Example 6, where the aging treatment temperature is 50°C to 150°C and the duration is 10min to 12h. Under the conditions of aging treatment temperature of 50°C to 150°C and a duration of 10min to 12h, the degradation of the tensile strength of the polyimide fiber over time can be controlled within 5%, achieving the purpose of maintaining the long-term stability of the mechanical properties of the polyimide fiber, solving the problem of a sharp drop in the tensile strength of the polyimide fiber over time, and greatly improving the durability of the mechanical properties of the polyimide fiber.
[0101] In Comparative Example 1, since no aging treatment was performed, after being placed for one year, the tensile strength value thereof dropped significantly by 44.1%.
[0102] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims
1. A method for preparing polyimide fiber, characterized in that: The following steps are involved: Prepare polyamic acid slurry by using diamine monomer, dianhydride monomer and organic solvent; The polyamic acid slurry is subjected to spinning imidization treatment to obtain a primary polyimide fiber product; The polyimide fiber primary product is subjected to aging treatment to obtain the polyimide fiber.
2. The method for preparing polyimide fiber according to claim 1, characterized in that: The temperature condition of the aging treatment is 50° C. to 150° C., and the duration is 10 min to 12 h.
3. The method for preparing polyimide fiber according to claim 1, characterized in that: The preparation step of the polyamic acid slurry comprises: dissolving the diamine monomer in the organic solvent under an inert atmosphere at a temperature of 40° C. to 50° C., cooling to 1° C. to 10° C., and then adding the dianhydride monomer for mixing to obtain the polyamic acid slurry; And / or, the viscosity of the polyamic acid slurry is 30000cps to 300000cps.
4. The method for preparing the polyimide fiber according to any one of claims 1 to 3, characterized in that: The diamine monomer includes at least one of 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminobenzanilide, 2-(4-aminophenyl)-5-aminobenzimidazole, and 2-(4-aminophenyl)-5-aminobenzoxazole; And / or, the dianhydride monomer includes at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-biphenyl ether dianhydride, and bisphenol A diether dianhydride; And / or, the molar ratio of the diamine monomer to the dianhydride monomer is (0.95-1.05):
1.
5. The method for preparing polyimide fiber according to claim 4, characterized in that: The diamine monomers include at least two of 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminobenzanilide, 2-(4-aminophenyl)-5-aminobenzimidazole, and 2-(4-aminophenyl)-5-aminobenzoxazole.
6. The method for preparing polyimide fiber according to any one of claims 1 to 3 or 5, characterized in that: The spinning imidization treatment step includes: the polyamic acid slurry is extruded through spinning metering at a spinning speed of 15 m / min to 25 m / min according to a linear density specification of 1000 dtex to 2000 dtex, and the polyamic acid undergoes a dehydration ring-closing reaction at a temperature of 400° C. to 600° C. to obtain the polyimide fiber primary product.
7. The method for preparing polyimide fiber according to claim 6, characterized in that: The organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, γ-butyrolactone, and cyclohexanone; And / or, the moisture content in the organic solvent is not higher than 300 ppm.
8. A polyimide fiber, characterized in that: The polyimide fiber is prepared by the method according to any one of claims 1 to 7.
9. The polyimide fiber according to claim 8, characterized in that The tensile strength of the polyimide fiber after storage for 12 months is ≥27 cN / dtex; And / or, the modulus of the polyimide fiber after storage for 12 months is ≥810 cN / dtex.
10. An application of polyimide fiber, characterized in that: The polyimide fiber prepared by the method according to any one of claims 1 to 7, or the polyimide fiber according to any one of claims 8 to 9 is applied to at least one field of aerospace, electronics industry, automobile industry, protective products, and shipbuilding.