High-strength and high-modulus heteroaromatic polyamide fiber and preparation method thereof

Abstract

The invention relates to the technical field of high-performance fibers, and discloses a high-strength and high-modulus heteroaromatic polyamide fiber and a preparation method thereof. The preparation method comprises the following steps: adding a diamine monomer and an aromatic diacyl chloride monomer into a composite solvent in multiple steps, and carrying out condensation polymerization to obtain an aromatic heterocyclic polyamide solution; the diamine monomer comprises a diamine monomer A with a heterocyclic structure, a diamine monomer B with a rigid rodlike structure and a diamine monomer C; the composite solvent is a DMAc solution of LiCl; sequentially filtering and defoaming the aromatic heterocyclic polyamide solution to obtain a spinning solution, and performing coagulation bath coagulation and plasticizing stretching to obtain nascent fibers; the nascent fiber is subjected to water washing, drying and heat treatment, and the high-strength and high-modulus aromatic heterocyclic polyamide fiber is obtained. Compared with a traditional low-temperature polycondensation process, the method has the advantages that a large number of rigid rod-shaped units are introduced, good solubility and processability of a polymer solution are still kept, polymerization time is shortened, efficiency is improved, and industrial large-scale production is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-performance fibers, in particular to a high-strength and high-modulus aromatic heterocyclic polyamide fiber and a preparation method thereof. BACKGROUND

[0002] Aromatic heterocyclic polyamide fiber (also known as heterocyclic aramid fiber) is a new generation of high-performance synthetic organic fiber, which contains aromatic ring, amide bond and heterocyclic structure in the molecular backbone. The special structure endows the fiber with excellent comprehensive performance, including high strength, high modulus, high dimensional stability and excellent heat resistance (thermal decomposition temperature can reach more than 500 ℃). In addition, the introduction of heterocyclic units improves the solubility and processability of the polymer, which has obvious advantages in preparation process and application expansion.

[0003] Due to its light weight, high strength, heat resistance, corrosion resistance and other characteristics, aromatic heterocyclic polyamide fiber has been widely used in aerospace, military protection and high-end equipment manufacturing fields. However, the existing aromatic heterocyclic polyamide fiber generally has the problem of insufficient molecular chain regularity, which limits the crystallinity and orientation degree of the fiber, resulting in further improvement space for the mechanical properties of the fiber, especially the initial modulus. How to improve the molecular chain regularity and orientation degree through the synergistic optimization of molecular structure design and fiber forming process to realize the high-strength and high-modulus of aromatic heterocyclic polyamide fiber is a key technical problem to be solved in this field.

[0004] The introduction of high-rigidity rod-like structural units is an effective way to improve the tensile strength and initial modulus of aryl heterocyclic polyamide fibers. Poly-p-phenylene benzobisoxazole (PBO) and poly(2,5-dihydroxy-1,4-phenylene pyridobisimidazole) fibers have highly rigid and conjugated rod-like molecular structures, which are prone to form high crystallinity and high orientation, thereby exhibiting excellent mechanical properties. For example, the initial modulus of PBO fiber can be as high as 280 GPa. In theory, the introduction of rigid rod-like monomers into the polymerization system through copolymerization modification can effectively improve the modulus of aryl heterocyclic polyamide fibers. However, the introduction of high-rigidity structural units often leads to poor solubility of polymer solutions and significantly increased solution viscosity, thereby reducing spinnability and affecting fiber formation and performance. For example, Chinese Patent CN 119591886 A discloses a preparation method of a heterocyclic aramid block copolymer containing a PBO structure and a fiber thereof. PBO blocks are generated by reacting 4,6-diamino-1,3-resorcinol (DAR) with terephthalic acid (PTA) in a polyphosphoric acid system. Then, p-phenylenediamine, 2-(4-aminophenyl)-5-aminobenzimidazole, and terephthaloyl chloride are polymerized in a DMAC / LiCl solvent to form another block. Subsequently, the two polymerization solutions are blended and spun into a fiber. Although this technology can improve the mechanical properties of the fiber to some extent, it requires the use of two different solvent systems, which is complex. Moreover, the PBO / polyphosphoric acid solution has a high viscosity at room temperature, which seriously affects the spinnability.

[0005] The synthesis and preparation of high-strength and high-modulus aryl heterocyclic polyamide fibers containing rigid rod-like structures face the core problem of the contradiction between solubility and high performance. Currently, there is still a lack of effective polymerization methods that can balance the rigidity of the polymer chain and solubility to break through this bottleneck. SUMMARY

[0006] The present application provides a high-strength and high-modulus aryl heterocyclic polyamide fiber and a preparation method thereof, aiming to solve the technical problems of the existing aryl heterocyclic polyamide fiber preparation method, such as the difficulty in balancing high performance and solubility, the high viscosity of rigid polymer liquid, and poor spinnability.

[0007] To achieve the above-mentioned purpose, the following technical solutions are adopted in the present application.

[0008] In a first aspect, the present application provides a preparation method of a high-strength and high-modulus aryl heterocyclic polyamide fiber, comprising: S1, a diamine monomer and an aromatic dichloride monomer are added to a composite solvent in multiple steps for a polycondensation reaction to obtain an aryl heterocyclic polyamide solution; The diamine monomer includes a heterocyclic structure-containing diamine monomer A, a rigid rod-like structure diamine monomer B, and a diamine monomer C. The composite solvent is a DMAc solution of LiCl. S2, the aromatic heterocyclic polyamide solution is sequentially filtered and defoamed to obtain a spinning dope, and the spinning dope is coagulated in a coagulation bath and plasticized and stretched to obtain a nascent fiber; S3, the nascent fiber is washed with water, dried, and heat treated to obtain a high-strength and high-modulus aromatic heterocyclic polyamide fiber.

[0009] Preferably, in S1, the molar content of the diamine monomer A is 40-90%, the molar content of the diamine monomer B is 10-50%, and the content of the diamine monomer C is 0-50%. The molar ratio of the diamine monomer to the aromatic dichloride monomer is 1:(0.98-1.02).

[0010] Preferably, S1 specifically comprises: S11, dissolving anhydrous LiCl in DMAc to prepare a composite solvent; S12, under nitrogen protection, adding diamine monomer B, diamine monomer C, and 70-90% of diamine monomer A based on the total mass into the composite solvent, stirring and dissolving to obtain a first intermediate liquid; S13, under nitrogen protection, adding 80-85% of the aromatic dichloride monomer based on the total mass into the intermediate liquid in multiple times, and heating to react under nitrogen protection to obtain a second intermediate liquid; S14, dissolving the remaining diamine monomer A in the second intermediate liquid to obtain a precursor liquid; S15, stirring and reacting the remaining aromatic dichloride monomer to obtain an aromatic heterocyclic polyamide solution.

[0011] Preferably, the diamine monomer A is 2-(4-aminophenyl)-5-aminobenzimidazole; The diamine monomer B includes at least one of 4,4'-(3,5-dihydrodiimidazo[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline) or 4,4'-(benzo[1,2-d:5,4-d']bis(oxazole)-2,6-diyl)bis(3-chloroaniline); The diamine monomer C includes any one of p-phenylenediamine, 2-chlorobenzene-1,4-diamine, 2-(4-aminophenyl)benzo[d]oxazole-5-amine, 5-amino-2-(5-aminobenzo[d]oxazole-2-yl)phenol, amino-N-(4-amino-phenyl)benzoyl, 4-amino-N-(4-amino-2-chlorophenyl)benzoyl, or naphthalene-2,6-diamine (NA-PDA); The aromatic dichloride monomer is terephthaloyl chloride.

[0012] Further preferably, the concentration of LiCl in the composite solvent is 2-8 wt%; In step S12, the control temperature is 30-80℃; the stirring time is 1-2h; In step S13, the reaction temperature is 30-80℃, and the reaction time is 0.5-3h; In step S14, the stirring time is 0.5-1h; In step S15, the reaction time is 0.5-3h.

[0013] Preferably, in step S2, the kinetic viscosity of the spinning dope is 30-100 thousand centipoise; The mass concentration of the aromatic heterocyclic polyamide in the spinning dope is 3-6wt%.

[0014] Preferably, in step S2, the coagulation bath is a mixed solution of N,N-dimethylacetamide and water; the volume ratio of N,N-dimethylacetamide to water is 1:1-7:3. The draw ratio of the plasticized drawing is 70-150%.

[0015] Preferably, in step S3, the temperature of the washing is 60-100℃; the temperature of the drying is 130-200℃.

[0016] Preferably, in step S3, the heat treatment is performed under the following conditions: The tension is 0.05-0.5 cN / dt, and the temperature is 400-500℃.

[0017] In a second aspect, the application provides a high-strength and high-modulus aromatic heterocyclic polyamide fiber prepared by the above preparation method.

[0018] Compared with the prior art, the application has the following beneficial effects: The preparation method of the application directly introduces a high-rigidity rod-like structural unit into a traditional aromatic heterocyclic polyamide system, significantly enhances the conjugated rigidity characteristics of the molecular chain, and introduces a side group carbon-chlorine bond (C-Cl) to improve the solubility; by using a high-temperature stepwise feeding strategy, the difference in reactivity of different diamine monomers and the polymerization order can be precisely controlled, and the problem of too large difference in reactivity between the chlorine-containing rigid rod-like diamine monomer and other diamine monomers (such as PABZ) under low temperature conditions can be effectively avoided, thereby preventing the formation of too long rigid block structures during polymerization. Compared with the traditional low-temperature polycondensation process, the application still maintains good solubility and processing performance of the polymer solution while introducing a large number of rigid rod-like units, shortens the polymerization time, improves the efficiency, and is conducive to realizing industrialized scale production.

[0019] The aryl heterocyclic polyamide fiber prepared by the application has excellent comprehensive mechanical properties, and the tensile strength thereof can reach 5.0-5.8 GPa, and the initial modulus thereof can reach 150-246 GPa, and the aryl heterocyclic polyamide fiber has high strength and high modulus, and has a wide application prospect in the fields of national defense and military industry, bulletproof protection, aerospace, transportation and the like. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0021] Figure 1 NMR hydrogen spectrum of 4,4'-(3,5-dihydrodiimidazo[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline) monomer prepared by the application in DMSO. Figure 2 NMR hydrogen spectrum of 4,4'-(3,5-dihydrodiimidazo[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline) monomer prepared by the application in DMSO. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the application will be described clearly and completely in the following description of the embodiments of the application in combination with the drawings of the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0023] In the following description of the embodiments of the application, the terms "comprise", "contain", "have" and "include" and the like are all open terms, that is, they mean including but not limited to.

[0024] In the following description of the embodiments of the application, the term "and / or" is used to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following three cases: A exists alone, B exists alone and A and B exist simultaneously. Wherein A and B can be singular or plural. The character " / " generally represents that the front and rear associated objects have an "or" relationship.

[0025] In the following description of the embodiments, the term "at least one" means one or more and the term "multiple" means two or more. The phrase "at least one of the following (one or more)" or similar expressions refers to any combination of the items, including single (one) or multiple items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can mean a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0026] The terms used in the embodiments of the present application are merely for the purpose of describing particular 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 intended to include plural forms as well, unless the context clearly indicates otherwise.

[0027] Those skilled in the art understand that in the following description of the embodiments of the present application, the order of the serial numbers does not mean the order of execution, and some or all steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0028] Those skilled in the art understand that the numerical ranges in the embodiments of the present application should be understood as each intermediate value between the upper limit and the lower limit of the range. Each smaller range between any stated value or stated range of intermediate values and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0029] Unless otherwise indicated, the technical / scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present application. All documents mentioned in the specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict between the contents of the specification and any incorporated document, the contents of the specification shall prevail.

[0030] In a first aspect, the present application provides a method for preparing a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, a diamine monomer and an aromatic dichloride monomer are fed into a composite solvent in multiple steps to perform a polycondensation reaction, to obtain an aromatic heterocyclic polyamide solution; In the present application, the diamine monomers include diamine monomer A containing a heterocyclic structure, diamine monomer B having a rigid rod-like structure, and diamine monomer C; among the diamine monomers, the molar content of diamine monomer A is 40-90%, the molar content of diamine monomer B is 10-50%, and the content of diamine monomer C is 0-50%.

[0031] Specifically, the diamine monomer A is 2-(4-aminophenyl)-5-aminobenzimidazole; The diamine monomer B is selected from at least one of 4,4'-(3,5-dihydrodiimidazo[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline) or 4,4'-(benzo[1,2-d:5,4-d']bis(oxazole)-2,6-diyl)bis(3-chloroaniline); The diamine monomer C is selected from any one of p-phenylenediamine, 2-chlorobenzene-1,4-diamine, 2-(4-aminophenyl)benzo[d]oxazole-5-amine, 5-amino-2-(5-aminobenzo[d]oxazol-2-yl)phenol, amino-N-(4-amino-phenyl)benzoyl, 4-amino-N-(4-amino-2-chlorophenyl)benzoyl, or naphthalene-2,6-diamine (NA-PDA).

[0032] In the present application, the aromatic dicarboxylic acid chloride monomer is terephthaloyl chloride; the complex solvent is a DMAc solution of LiCl; and the concentration of LiCl in the complex solvent is preferably 2-8 wt%.

[0033] In the present application, the molar ratio of the diamine monomers to the aromatic dicarboxylic acid chloride monomer is 1:(0.98-1.02). That is, the number of moles of the aromatic dicarboxylic acid chloride monomer can be slightly less than or slightly more than the theoretical value. When the molar ratio of the two is 1:(0.98-1), the aromatic dicarboxylic acid chloride monomer is in a deficiency; and when the molar ratio of the two is 1:(1-1.02), the aromatic dicarboxylic acid chloride monomer is in a slight excess.

[0034] Specifically, the diamine monomers and the aromatic dicarboxylic acid chloride monomers are added to the complex solvent in multiple steps to carry out a polycondensation reaction to obtain a heteroaromatic polyamide solution, and the steps include the following: S11, dissolving anhydrous LiCl in DMAc to prepare a complex solvent; wherein the concentration of LiCl in the complex solvent is 2-8 wt%; S12, under the protection of nitrogen, adding diamine monomer B, diamine monomer C, and 70-90% of diamine monomer A based on the total mass to the complex solvent, controlling the temperature to be 30-80℃, and stirring and dissolving for 1-2 h to obtain a first intermediate liquid; S13, under the protection of nitrogen, the aromatic diacid chloride monomer accounting for 80-85% of the total mass is added into the intermediate liquid in multiple times, and the reaction is carried out at 30-80°C for 0.5-3h under the protection of nitrogen to obtain a second intermediate liquid; S14, the remaining diamine monomer A is dissolved in the second intermediate liquid, and stirred for 0.5-1h to obtain a precursor liquid; S15, the remaining aromatic diacid chloride monomer is stirred and reacted for 0.5-3h to obtain an aromatic heterocyclic polyamide solution.

[0035] S2, the aromatic heterocyclic polyamide solution is sequentially subjected to filtration and defoaming to obtain a spinning dope, and the spinning dope is coagulated in a coagulation bath and plasticized and stretched to obtain a nascent fiber; In the present application, the kinetic viscosity of the spinning dope is 30-100kpoise; and the mass concentration of the aromatic heterocyclic polyamide in the spinning dope is 3-6wt%.

[0036] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water, wherein the volume ratio of N,N-dimethylacetamide to water is 1:1-7:3. The stretching ratio of the plasticized and stretched is 70-150%.

[0037] S3, the nascent fiber is washed with water, dried and heat treated to obtain a high-strength and high-modulus aromatic heterocyclic polyamide fiber.

[0038] Preferably, the temperature of the water washing is 60-100°C; and the temperature of the drying is 130-200°C. The heat treatment is carried out under the conditions of a tension of 0.05-0.5cN / dt and a temperature of 400-500°C.

[0039] In the present application, a high-rigidity rod-like structural unit is directly introduced into a traditional aromatic heterocyclic polyamide system to significantly enhance the conjugated rigidity characteristics of the molecular chain, and a side group C-Cl bond is introduced to improve the solubility.

[0040] In the present application, a high-temperature stepwise feeding strategy is adopted to accurately control the difference in reactivity and polymerization order of different diamine monomers, and the problem of too large difference in reactivity between the chlorine-containing rigid rod-like diamine monomer and other diamine monomers (such as PABZ) under low temperature conditions can be effectively avoided, so as to prevent the formation of too long rigid block structure in the polymerization process.

[0041] Compared with the traditional low-temperature polycondensation process, the present application still maintains good solubility and processing performance of the polymer solution while introducing a large number of rigid rod-like units, shortens the polymerization time, improves the efficiency, and is conducive to realizing industrialized scale production.

[0042] The aryl heterocyclic polyamide fiber prepared in the application has excellent comprehensive mechanical properties, the tensile strength thereof can reach 5.0-5.8 GPa, the initial modulus thereof can reach 150-246 GPa, and the aryl heterocyclic polyamide fiber has high strength and high modulus; and the aryl heterocyclic polyamide fiber can be applied in the fields of national defense and military industry, bulletproof protection, aerospace and transportation.

[0043] The application is further illustrated by the following examples.

[0044] In the examples and comparative examples of the application, the correspondence between the compounds and the abbreviations is as follows: PABZ refers to 2-(4-aminophenyl)-5-aminobenzimidazole Cl-PBOA refers to 4,4'-(benzo[1,2-d:5,4-d']bis(oxazole)-2,6-diyl)bis(3-chloroaniline) PDA refers to p-phenylenediamine DABA-Cl refers to 4-amino-N-(4-amino-2-chlorophenyl)benzamide Cl-PDA refers to 2-chlorobenzene-1,4-diamine Cl-N-DPABZ refers to 4,4'-(3,5-dihydroimidazo[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline) DABA refers to amino-N-(4-amino-phenyl)benzamide BOA refers to 2-(4-aminophenyl)benzo[d]oxazole-5-amine HBOA refers to 5-amino-2-(5-aminobenzo[d]oxazole-2-yl)phenol NA-PDA refers to naphthalene-2,6-diamine Example Preparation of chlorine-containing rigid rod-shaped diamine monomer Cl-PBOA The synthesis process is as follows:

[0045] The preparation method is as follows: Add 100 g of polyphosphoric acid and 6.0 g of phosphorus pentoxide to a 1000 ml three-necked flask, place it in an oil bath at 60 °C, and mechanically stir until homogeneous under nitrogen atmosphere. Then add 0.25 g of antioxidant SnCl2·2H2O, raise the temperature to 80 °C, add 10.0 g of 4,6-diamino-1,3-resorcinol hydrochloride, stir until homogeneous, then add 8.05 g of 2-chloro-4-aminosalicylic acid in an equimolar ratio, stir until homogeneous, raise the temperature to 185 °C and react for 5 h to terminate the reaction. After the reaction solution cools to 120 °C, pour it into a vigorously stirred ice water bath, and collect the residue by vacuum filtration. The filter residue was dispersed in water, washed with NaHCO3 aqueous solution to remove excess phosphoric acid, and the pH was adjusted to 8. The filter residue was collected again by vacuum filtration and dried to obtain 4,4'-(benzo[1,2-d:5,4-d']bis(oxazol)-2,6-diyl)bis(3-chloroaniline), i.e. Cl-PBOA.

[0046] The product was tested, and its 1H NMR spectrum in DMSO is shown below. Figure 1 As shown, from Figure 1 It is known that 4,4'-(benzo[1,2-d:5,4-d']bis(oxazol)-2,6-diyl)bis(3-chloroaniline) was successfully prepared.

[0047] Example: Preparation of chlorine-containing rigid rod-shaped monomer Cl-N-DPABZ The synthesis process is as follows:

[0048] Under a nitrogen atmosphere, compound 3 (1.33 g, 5.0 mmol), compound 4' (1.71 g, 10.0 mmol), and polyphosphoric acid (10 g) were added sequentially to a round-bottom flask. The flask was refluxed and stirred for 12 h under nitrogen protection in an oil bath at 220 °C. After the reaction was completed, the mixture was cooled to room temperature and transferred to a 5% sodium hydroxide solution (200 mL). The pH of the sodium hydroxide solution was then adjusted to 8-9, and the crude product was obtained by filtration. The crude product was washed twice with a 5% sodium hydroxide solution (30 mL) and three times with water (30 mL), and dried to obtain monomer 5', which is 4,4'-(3,5-dihydrodiimidazole[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline), i.e., Cl-N-DPABZ.

[0049] The monomer 5' was tested, and its 1H NMR spectrum in DMSO is shown below. Figure 2 As shown, from Figure 2 It is known that 4,4'-(3,5-dihydrodiimidazole[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline) was successfully prepared.

[0050] Embodiment 1 The embodiment provides a preparation method of high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising the following steps: S1, 1166g of N,N-dimethylacetamide is added into a polymerization kettle, and then 42.3g of anhydrous lithium chloride is added and stirred until completely dissolved to obtain a composite solvent with a content of 3.5%wt of LiCl; The diamine monomers are weighed, wherein the PABZ is 21.235g, and the Cl-PBOA is 6.872g, and the molar ratio of the PABZ to the Cl-PBOA is 17:3. All the Cl-PBOA and 88.2% of the total mass of the PABZ, namely 18.729g, are added into the reaction kettle, and stirring is performed at 30 DEG C for 1h under the protection of nitrogen;

[0051] According to the solid content of 3.5% of the polymer material, the theoretical total feeding amount of terephthaloyl chloride (TPC) is calculated to be 22.61g through a reaction equation. 80% of the theoretical total feeding amount of the TPC is averagely divided into 6 times for pre-polymerization, namely 3.015g each time, and the feeding is performed once every 0.3h, and the polymerization kettle is controlled at 30 DEG C. After the feeding of the TPC is completed, stirring is performed for 0.3h, and then the remaining 2.506g of the PABZ is added into the polymerization kettle, and stirring and dissolution are performed at 30 DEG C for 0.35h.

[0052] 4.297g of the TPC is added into the polymerization kettle to 99% of the total mass, and stirring is performed for 0.5h to obtain an aromatic heterocyclic polyamide solution, and sampling detection is performed, and the dynamic viscosity is 650,000 centipoises.

[0053] The chemical reaction in the step S1 is as follows:

[0054] S2, the aromatic heterocyclic polyamide solution is filtered and defoamed, and then is transferred into a spinning storage tank, is extruded through a metering pump, and then enters a coagulation bath tank to form a primary fiber and is stretched by a traction roller to obtain the primary fiber; wherein the coagulation bath is a 68%wt DMAc aqueous solution, and the stretching ratio is 150%.

[0055] S3, the primary fiber is washed with deionized water at 90 DEG C, and then is dried at 160 DEG C to obtain a raw yarn; the raw yarn is continuously connected into a heat treatment oven through an unwinding machine and a traction roller, and is heat treated at a temperature of 430 DEG C and a traction tension of 0.05 cN / dt for 1min to obtain the aromatic heterocyclic polyamide fiber.

[0056] Embodiment 2 The embodiment provides a preparation method of high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising the following steps: S1, 799 g of N,N-dimethylacetamide was added into the polymerization kettle, and then 28.3 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a LiCl content of 3.5%wt; The diamine monomers were weighed, wherein PABZ was 15.4 g and Cl-PBOA was 3.138 g, and the molar ratio of PABZ to Cl-PBOA was 9:1. All of the Cl-PBOA and 89% of the total mass of PABZ, i.e., 13.706 g, were added into the reaction kettle, and stirred at 30°C for 1 h under nitrogen protection;

[0057] According to the polymer material solid content of 3.5%, the theoretical total amount of terephthaloyl chloride (TPC) was calculated to be 23.235 g by the reaction equation. 80% of the theoretical total amount of TPC was divided into 6 times and added into the polymerization kettle for prepolymerization, i.e., 3.098 g each time, and the polymerization kettle was controlled at a temperature of 30°C. After the addition of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 1.694 g of PABZ was added into the polymerization kettle and stirred and dissolved at 30°C for 0.35 h.

[0058] 4.415 g of TPC was added into the polymerization kettle to 99% of the total mass, and stirred for 1 h to obtain an aromatic heterocyclic polyamide solution, and the sample was detected, and the kinetic viscosity was 7.1 million centipoise.

[0059] S2, after the aromatic heterocyclic polyamide solution was filtered and defoamed, it was transferred into a spinning storage tank, and then extruded through a metering pump into a coagulation bath tank for primary fiber formation and plasticizing stretching by a traction roller to obtain a primary fiber; wherein the coagulation bath was a 66%wt DMAc aqueous solution, and the stretching ratio was 100%.

[0060] S3, the primary fiber was washed with deionized water at 90°C, and then dried at 130°C to obtain a raw yarn; the raw yarn was continuously introduced into a heat treatment oven through an unwinding machine and a traction roller, and heat treated at a temperature of 480°C and a traction tension of 0.1 cN / dt for 0.5 min to obtain an aromatic heterocyclic polyamide fiber.

[0061] Example 3 The present embodiment provides a preparation method of a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 804 g of N,N-dimethylacetamide was added into the polymerization kettle, and then 28.14 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a LiCl content of 3%wt; The diamine monomers were weighed, wherein the molar ratio of PABZ, Cl-PBOA and PDA was 11:3:6. All of the Cl-PBOA, all of the PDA and 83.3% of the total mass of PABZ, i.e. 7.403 g, were added to the reaction kettle, and stirring was performed at 40°C for 1 h under nitrogen protection;

[0062] The theoretical total amount of terephthaloyl chloride (TPC) was calculated to be 14.63 g according to the reaction equation, with the solid content of the polymer being 3%. 80% of the theoretical total amount of TPC was added to the polymerization kettle in four equal portions, i.e. 2.926 g each time, with one portion being added every 0.3 h, and the temperature of the polymerization kettle was controlled at 40°C. After the addition of TPC was completed, stirring was performed for 0.3 h, and then the remaining 2.506 g of PABZ was added to the polymerization kettle, and stirring and dissolution were performed at 40°C for 0.35 h.

[0063] 2.779 g of TPC was added to the polymerization kettle to reach 99% of the total mass, and stirring was performed for 0.5 h to obtain an aromatic heterocyclic polyamide solution, and sampling detection showed that the kinetic viscosity of the solution was 61,000 centipoise.

[0064] S2, after the aromatic heterocyclic polyamide solution was filtered and defoamed, it was transferred to a spinning storage tank, and then was extruded through a metering pump into a coagulation bath tank to form a nascent fiber and was plasticized and stretched by a traction roller to obtain the nascent fiber; the coagulation bath was a 55%wt DMAc aqueous solution, and the stretching ratio was 120%.

[0065] S3, the nascent fiber was washed with deionized water at 60°C, and then was dried at 180°C to obtain a raw yarn; the raw yarn was continuously introduced into a heat treatment oven through an unwinding machine and a traction roller, and was heat treated at a temperature of 430°C and a traction tension of 0.15 cN / dt for 2 min to obtain an aromatic heterocyclic polyamide fiber.

[0066] Example 4 The present embodiment provides a method for preparing a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 862 g of N,N-dimethylacetamide was added to a polymerization kettle, and then 43.1 g of anhydrous lithium chloride was added, and stirring was performed until complete dissolution to obtain a composite solvent with a LiCl content of 5%wt; The diamine monomers were weighed, wherein the molar ratio of PABZ, Cl-PBOA and PDA was 11:3:6. All of the Cl-PBOA, all of the PDA and 83.3% of the total mass of PABZ, i.e. 7.403 g, were added to the reaction kettle, and stirring was performed at 40°C for 1 h under nitrogen protection;

[0067] The total theoretical amount of terephthaloyl chloride (TPC) was 19.06 g, calculated by the reaction equation, with the solid content of the polymer material being 3.5%. 80% of the total theoretical amount of TPC was added to the polymerization kettle in 8 equal portions, i.e. 1.906 g each time, with an interval of 0.3 h, and the polymerization kettle was controlled at a temperature of 50°C. After the addition of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 2.104 g of PABZ was added to the polymerization kettle, which was stirred and dissolved at 70°C for 0.35 h.

[0068] 4.002 g of TPC was added to the polymerization kettle to account for 101% of the total mass, and the reaction was stirred for 1 h to obtain an aromatic heterocyclic polyamide solution, which was sampled and detected to have a kinetic viscosity of 85,000 centipoises.

[0069] S2, after the aromatic heterocyclic polyamide solution was filtered and defoamed, it was transferred to a spinning storage tank, extruded through a metering pump, and then introduced into a coagulation bath tank to form a primary fiber and be stretched by a traction roller, thereby obtaining a primary fiber; wherein the coagulation bath was a 66%wt DMAc aqueous solution, and the draw ratio was 120%.

[0070] S3, the primary fiber was washed with deionized water at 75°C, and then dried at 200°C to obtain a raw yarn; the raw yarn was continuously introduced into a heat treatment oven through an unwinding machine and a traction roller, and heat treated at a temperature of 430°C and a traction tension of 0.4 cN / dt for 1.5 min, thereby obtaining an aromatic heterocyclic polyamide fiber.

[0071] Example 5 The present embodiment provides a method for preparing a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 1037 g of N,N-dimethylacetamide was added to a polymerization kettle, and then 20.7 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent containing 2%wt of LiCl; The diamine monomers were weighed, wherein the PABZ was 10.159 g, the Cl-PBOA was 11.178 g, and the DABA-Cl was 4.742 g, and the molar ratio of PABZ, Cl-PBOA and DABA-Cl was 5:3:2. All of the Cl-PBOA, all of the DABA-Cl, and 70% of the total mass of PABZ, i.e. 7.111 g, were added to the reaction kettle, which was stirred at 60°C for 1 h under nitrogen protection;

[0072] The total theoretical amount of terephthaloyl chloride (TPC) was calculated to be 18.391 g according to the reaction equation with the solid content of the polymer material being 3.5%. 85% of the total theoretical amount of TPC was added into the polymerization kettle in 8 times for pre-polymerization, i.e. 1.954 g each time, with an interval of 0.3 h, and the temperature of the polymerization kettle was controlled at 60°C. After the addition of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 3.048 g of PABZ was added into the polymerization kettle and stirred and dissolved at 60°C for 0.5 h.

[0073] 2.759 g of TPC was added into the polymerization kettle to account for 100% of the total mass, and the reaction was stirred for 1 h to obtain an aromatic heterocyclic polyamide solution, which was sampled and detected to have a kinetic viscosity of 6.1 million centipoises.

[0074] S2, the aromatic heterocyclic polyamide solution was filtered and defoamed, and then transferred into a spinning storage tank, extruded through a metering pump, and then introduced into a coagulation bath tank for primary fiber formation and plasticized stretching by a traction roller to obtain a primary fiber; wherein the coagulation bath was a 64%wt DMAc aqueous solution, and the stretching ratio was 130%.

[0075] S3, the primary fiber was washed with deionized water at 90°C, and then dried at 150°C to obtain a raw yarn; the raw yarn was continuously introduced into a heat treatment oven through an unwinding machine and a traction roller, and heat treated at a temperature of 450°C and a traction tension of 0.45 cN / dt for 1 min to obtain an aromatic heterocyclic polyamide fiber.

[0076] Example 6 The present embodiment provides a method for preparing a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 750 g of N,N-dimethylacetamide was added into a polymerization kettle, and then 15.25 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a content of 2%wt of LiCl; The diamine monomers were weighed, wherein the PABZ was 8.643 g, the Cl-PBOA was 5.286 g, the PDA was 2.778 g, and the Cl-PDA was 1.266 g, and the molar ratio of PABZ, Cl-PBOA, PDA and Cl-PDA was 9:3:6:2. All of the Cl-PBOA, all of the PDA, all of the Cl-PDA, and 77.8% of the total mass of PABZ, i.e. 6.724 g, were added into the reaction kettle, and stirred at 40°C for 1 h under nitrogen protection;

[0077] The total theoretical amount of TPC was 17.406 g according to the reaction equation, with the solid content of the polymer material being 3.5%. 80% of the total theoretical amount of TPC was added to the polymerization kettle in five equal portions, i.e. 2.785 g each time, with an interval of 0.3 h, and the temperature of the polymerization kettle was controlled at 40°C. After the addition of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 1.919 g of PABZ was added to the polymerization kettle, which was stirred and dissolved at 80°C for 0.4 h.

[0078] 3.307 g of TPC was added to the polymerization kettle to account for 99% of the total mass, and the reaction was stirred for 0.6 h to obtain an aromatic heterocyclic polyamide solution. The kinetic viscosity of the sample was 6.3 million centipoise.

[0079] S2, the aromatic heterocyclic polyamide solution was filtered and degassed, and then transferred to a spinning storage tank. After being extruded by a metering pump, the solution entered a coagulation bath tank to form a primary fiber and was stretched by a traction roller to obtain a primary fiber. The coagulation bath was a 60%wt DMAc aqueous solution, and the draw ratio was 150%.

[0080] S3, the primary fiber was washed with deionized water at 100°C, and then dried at 180°C to obtain a raw yarn. The raw yarn was continuously fed into a heat treatment oven through an unwinding machine and a traction roller, and was heat treated at a temperature of 500°C and a traction tension of 0.5 cN / dt for 1 min to obtain an aromatic heterocyclic polyamide fiber.

[0081] Example 7 The present embodiment provides a method for preparing a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 772 g of N,N-dimethylacetamide was added to the polymerization kettle, and then 27.02 g of anhydrous lithium chloride was added. After stirring until completely dissolved, a composite solvent containing 3.5%wt of LiCl was obtained; The diamine monomers were weighed, wherein the PABZ was 16.336 g, the Cl-N-DPABZ was 14.979 g, and the DABA was 2.759 g. The molar ratio of PABZ, Cl-N-DPABZ and DABA was 6:3:1. All of the DABA, all of the Cl-N-DPABZ, and 70% of the total mass of PABZ, i.e. 11.435 g, were added to the reaction kettle, which was stirred at 30°C for 1 h under nitrogen protection;

[0082] The total theoretical feeding amount of terephthaloyl chloride (TPC) was 24.65 g according to the reaction equation, with the solid content of the polymer material being 6%. 80% of the total theoretical feeding amount of TPC was divided into 5 equal parts and fed into the polymerization kettle for pre-polymerization, i.e. 3.944 g each time, with a feeding interval of 0.3 h, and the polymerization kettle was controlled at a temperature of 25°C. After the feeding of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 4.901 g of PABZ was added to the polymerization kettle and stirred and dissolved at 25°C for 0.4 h.

[0083] 5.423 g of TPC was fed into the polymerization kettle to account for 102% of the total mass of the polymerization kettle, and the reaction was stirred for 3 h to obtain an aromatic heterocyclic polyamide solution, which was sampled and detected to have a kinetic viscosity of 63 million centipoises.

[0084] S2, after the aromatic heterocyclic polyamide solution was filtered and defoamed, it was transferred into a spinning storage tank, extruded through a metering pump, and then introduced into a coagulation bath tank for primary fiber formation and plasticized stretching by a traction roller to obtain a primary fiber; wherein the coagulation bath was a 56%wt DMAc aqueous solution, and the draw ratio was 120%.

[0085] S3, the primary fiber was washed with deionized water at 100°C, and then dried at 150°C to obtain a raw yarn; the raw yarn was continuously introduced into a heat treatment oven through an unwinding machine and a traction roller, and heat treated at a temperature of 450°C and a traction tension of 0.35 cN / dt for 1.5 min to obtain an aromatic heterocyclic polyamide fiber.

[0086] Example 8 The present embodiment provides a method for preparing a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 978 g of N,N-dimethylacetamide was added to a polymerization kettle, and then 78.24 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent containing 8%wt of LiCl; The diamine monomers were weighed, wherein the PABZ was 11.706 g, the Cl-PBOA was 10.733 g, and the BOA was 1.959 g, and the molar ratio of PABZ, Cl-PBOA and BOA was 10:3:7. All of the Cl-PBOA, all of the BOA, and 89% of the total mass of PABZ, i.e. 10.418 g, were added to the reaction kettle, and stirred at 60°C for 1 h under nitrogen protection;

[0087] The total theoretical feeding amount of terephthaloyl chloride (TPC) was 17.661 g according to the reaction equation with the solid content of the polymer material being 3.5%. 85% of the total theoretical feeding amount of TPC was divided into three times to be fed into the polymerization kettle for pre-polymerization, i.e. 5.004 g each time, and the feeding was performed once every 0.3 h, and the temperature of the polymerization kettle was controlled at 30°C. After the feeding of TPC was completed, the stirring reaction was performed for 0.3 h, and then the remaining 1.288 g of PABZ was added into the polymerization kettle, and the stirring and dissolution were performed at 60°C for 0.35 h.

[0088] 2.862 g of TPC was fed into the polymerization kettle to account for 101% of the total mass of the polymerization kettle, and the stirring reaction was performed for 2 h to obtain an aromatic heterocyclic polyamide solution, and the sample detection showed that the kinetic viscosity was 6.5 million centipoises.

[0089] S2, after the aromatic heterocyclic polyamide solution was filtered and defoamed, it was transferred into a spinning storage tank, and then was extruded through a metering pump to enter a coagulation bath tank to form a primary fiber and was plasticized and stretched by a traction roller to obtain the primary fiber; wherein the coagulation bath was a 55%wt DMAc aqueous solution, and the stretching ratio was 110%.

[0090] S3, the primary fiber was washed with deionized water at 80°C, and then was dried at 200°C to obtain a raw yarn; the raw yarn was continuously introduced into a heat treatment oven through an unwinding machine and a traction roller, and was heat treated at a temperature of 450°C and a traction tension of 0.08 cN / dt for 1 min to obtain the aromatic heterocyclic polyamide fiber.

[0091] Example 9 The embodiment provides a preparation method of a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 1027 g of N,N-dimethylacetamide was added into a polymerization kettle, and then 35.95 g of anhydrous lithium chloride was added, and the stirring was performed until the lithium chloride was completely dissolved to obtain a composite solvent with the content of lithium chloride being 3.5%wt; The diamine monomers were weighed, wherein the PABZ was 12.244 g, the Cl-N-DPABZ was 11.226 g, and the HBOA was 2.195 g, and the molar ratio of PABZ, Cl-N-DPABZ and HBOA was 6:3:1. All the Cl-N-DPABZ, all the HBOA and 77.8% of the total mass of PABZ, i.e. 9.526 g, were added into the reaction kettle, and the stirring was performed at 40°C for 1 h under the protection of nitrogen.

[0092] The total theoretical feeding amount of terephthaloyl chloride (TPC) was 18.473 g according to the reaction equation, with the solid content of the polymer material being 6%. 80% of the total theoretical feeding amount of TPC was divided into three times and fed into the polymerization kettle for pre-polymerization, i.e. 4.926 g each time, with a feeding interval of 0.3 h, and the temperature of the polymerization kettle was controlled at 40°C. After the feeding of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 2.718 g of PABZ was added to the polymerization kettle, which was stirred and dissolved at 40°C for 0.5 h.

[0093] 3.32 g of TPC was fed into the polymerization kettle to account for 99% of the total mass, and the reaction was stirred for 1.5 h to obtain an aromatic heterocyclic polyamide solution, which was sampled and detected to have a kinetic viscosity of 70,000 centipoises.

[0094] S2, the aromatic heterocyclic polyamide solution was filtered and defoamed, and then transferred into a spinning storage tank. After being extruded by a metering pump, the solution entered a coagulation bath tank to form a primary fiber and was stretched by a traction roller to obtain the primary fiber; wherein the coagulation bath was a 55%wt DMAc aqueous solution, and the stretching ratio was 150%.

[0095] S3, the primary fiber was washed with deionized water at 80°C, and then dried at 155°C to obtain a raw yarn. The raw yarn was continuously fed into a heat treatment oven through an unwinding machine and a traction roller, and heat treated at a temperature of 400°C and a traction tension of 0.14 cN / dt for 2 min to obtain an aromatic heterocyclic polyamide fiber.

[0096] Example 10 The present embodiment provides a method for preparing a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 875 g of N,N-dimethylacetamide was added to a polymerization kettle, and then 30.07 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent containing 3.5%wt of LiCl; The diamine monomers were weighed, wherein the PABZ was 9.098 g, the Cl-PBOA was 4.172 g, the PDA was 3.288 g, and the NA-PDA was 3.207 g. The molar ratio of PABZ, Cl-PBOA, PDA and NA-PDA was 4:1:3:2. 80% of the total mass of Cl-PBOA, PDA, NA-PDA and PABZ, i.e. 7.278 g, was added to the reaction kettle, which was stirred at 50°C for 1 h under nitrogen protection;

[0097] The total theoretical feeding amount of terephthaloyl chloride (TPC) was calculated to be 20.603 g according to the reaction equation with the solid content of the polymer material being 3.5%. 80% of the total theoretical feeding amount of TPC was evenly divided into 6 times to be fed into the polymerization kettle for pre-polymerization, i.e. 2.747 g each time, and the feeding was performed once every 0.3 h, and the temperature of the polymerization kettle was controlled at 30°C. After the feeding of TPC was completed, the stirring reaction was performed for 0.3 h, and then the remaining 1.820 g of PABZ was added into the polymerization kettle, and the stirring and dissolution were performed at 30°C for 0.5 h.

[0098] 3.709 g of TPC was fed into the polymerization kettle to account for 98% of the total mass of the polymerization kettle, and the stirring reaction was performed for 2 h to obtain an aromatic heterocyclic polyamide solution, and the sample detection showed that the kinetic viscosity was 30,000 centipoises.

[0099] S2, after the aromatic heterocyclic polyamide solution was filtered and defoamed, it was transferred into a spinning storage tank, and then was extruded through a metering pump to enter a coagulation bath tank to form a primary fiber and was plasticized and stretched by a traction roller to obtain the primary fiber; wherein the coagulation bath was a 70%wt DMAc aqueous solution, and the stretching ratio was 70%.

[0100] S3, the primary fiber was washed with deionized water at 90°C, and then was dried at 130°C to obtain a raw yarn; the raw yarn was continuously fed into a heat treatment oven through an unwinding machine and a traction roller, and was heat treated at a temperature of 450°C and a traction tension of 0.35 cN / dt for 1 min to obtain an aromatic heterocyclic polyamide fiber.

[0101] Example 11 The present embodiment provides a preparation method of a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 912 g of N,N-dimethylacetamide was added into a polymerization kettle, and then 48 g of anhydrous lithium chloride was added, and the stirring was performed until the lithium chloride was completely dissolved to obtain a composite solvent with the content of lithium chloride being 5%wt; The diamine monomers were weighed, wherein the PABZ was 8.34 g, the Cl-PBOA was 6.117 g, and the Cl-N-DPABZ was 9.154 g, and the molar ratio of PABZ, Cl-PBOA and Cl-N-DPABZ was 5:2:3. All of the Cl-N-DPABZ, all of the Cl-PBOA and 85% of the total mass of PABZ, i.e. 7.089 g, were added into the reaction kettle, and the stirring was performed at 60°C for 1 h under the protection of nitrogen;

[0102] The total theoretical feeding amount of terephthaloyl chloride (TPC) was 15.101 g according to the reaction equation with the solid content of the polymer material being 3.5%. 80% of the total theoretical feeding amount of TPC was divided into three times to be fed into the polymerization kettle for pre-polymerization, i.e. 4.027 g each time, and the feeding was performed once every 0.3 h, and the temperature of the polymerization kettle was controlled at 40°C. After the feeding of TPC was completed, the stirring reaction was performed for 0.3 h, and then the remaining 1.251 g of PABZ was added into the polymerization kettle, and the stirring and dissolution were performed at 60°C for 0.5 h.

[0103] 2.869 g of TPC was fed into the polymerization kettle to account for 99% of the total mass, and the stirring reaction was performed for 2 h to obtain an aromatic heterocyclic polyamide solution, and the sample detection showed that the kinetic viscosity was 100,000 centipoises.

[0104] S2, after the aromatic heterocyclic polyamide solution was filtered and defoamed, it was transferred into a spinning storage tank, and then was extruded through a metering pump to enter a coagulation bath tank to form a primary fiber and was plasticized and stretched by a traction roller to obtain the primary fiber; wherein the coagulation bath was a 50%wt DMAc aqueous solution, and the stretching ratio was 150%.

[0105] S3, the primary fiber was washed with deionized water at 80°C, and then was dried at 150°C to obtain a raw yarn; the raw yarn was continuously introduced into a heat treatment oven through an unwinding machine and a traction roller, and the heat treatment was performed at a temperature of 450°C and a traction tension of 0.1 cN / dt for 2 min to obtain the aromatic heterocyclic polyamide fiber.

[0106] Example 12 The present embodiment provides a preparation method of a high-strength and high-modulus aromatic heterocyclic polyamide fiber, comprising: S1, 900 g of N,N-dimethylacetamide was added into a polymerization kettle, and then 31.5 g of anhydrous lithium chloride was added, and the stirring was performed until the lithium chloride was completely dissolved to obtain a composite solvent with the content of lithium chloride being 3.5%wt; The diamine monomers were weighed, wherein the PABZ was 11.10 g, the Cl-N-DPABZ was 10.154 g, and the PDA was 0.891 g, and the molar ratio of PABZ, Cl-N-DPABZ and PDA was 6:3:1. All of the Cl-N-DPABZ, all of the PDA and 77.8% of the total mass of PABZ, i.e. 8.636 g, were added into the reaction kettle, and the stirring was performed at 50°C for 1 h under the protection of nitrogen;

[0107] According to the solid content of the polymer material of 3.5%, the theoretical total feeding amount of terephthaloyl chloride (TPC) is calculated to be 16.746 g by reaction equation. 80% of the theoretical total feeding amount of TPC is divided into three times to be fed into the polymerization kettle for pre-polymerization, that is, 4.466 g each time, and the feeding interval is 0.3 h, and the temperature of the polymerization kettle is controlled at 40°C. After the feeding of TPC is completed, the reaction is stirred for 0.3 h, and then the remaining 2.465 g of PABZ is added into the polymerization kettle, and the stirring and dissolution are carried out at 50°C for 0.5 h.

[0108] Into the polymerization kettle, 3.015 g of TPC is fed to 98% of the total mass, and the reaction is stirred for 1 h to obtain an aromatic heterocyclic polyamide solution, and the sample detection shows that the kinetic viscosity is 53,000 centipoises.

[0109] S2, after the aromatic heterocyclic polyamide solution is filtered and defoamed, it is transferred into a spinning storage tank, and then is extruded through a metering pump to enter a coagulation bath tank to form a primary fiber and is plasticized and stretched by a traction roller to obtain a primary fiber; wherein the coagulation bath is a 55%wt DMAc aqueous solution, and the stretching ratio is 150%.

[0110] S3, the primary fiber is washed with deionized water at 70°C, and then is dried at 180°C to obtain a raw yarn; the raw yarn is continuously fed into a heat treatment oven through an unwinding machine and a traction roller, and is heat treated at a temperature of 430°C and a traction tension of 0.12 cN / dt for 2 min to obtain an aromatic heterocyclic polyamide fiber.

[0111] Comparative Example 1 S1, into the polymerization kettle, 928 g of N,N-dimethylacetamide is added, and then 33.7 g of anhydrous lithium chloride is added, and the stirring is carried out until the lithium chloride is completely dissolved to obtain a composite solvent with a lithium chloride content of 3.5%wt; The diamine monomer is weighed, wherein the PABZ is 21.464 g; into the reaction kettle, 88.2% of the total mass of PABZ, that is, 18.931 g, is added, and the stirring is carried out at 30°C for 1 h under the protection of nitrogen; According to the solid content of the polymer material of 3.5%, the theoretical total feeding amount of terephthaloyl chloride (TPC) is calculated to be 19.238 g by reaction equation. 80% of the theoretical total feeding amount of TPC is divided into six times to be fed into the polymerization kettle for pre-polymerization, that is, 2.565 g each time, and the feeding interval is 0.3 h, and the temperature of the polymerization kettle is controlled at 30°C. After the feeding of TPC is completed, the reaction is stirred for 0.3 h, and then the remaining 2.543 g of PABZ is added into the polymerization kettle, and the stirring and dissolution are carried out at 30°C for 0.35 h.

[0112] Into the polymerization kettle, 3.848 g of TPC is fed to 99% of the total mass, and the reaction is stirred for 0.5 h to obtain an aromatic heterocyclic polyamide solution, and the sample detection shows that the kinetic viscosity is 62,000 centipoises.

[0113] S2, same as example 1; S3, same as example 1.

[0114] Comparative example 2 S1, 1027 g of N,N-dimethylacetamide was added into the polymerization kettle, and then 35.95 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a LiCl content of 3.5%wt; The diamine monomers were weighed, of which PABZ was 7.205 g and Cl-PBOA was 19.819 g, and the molar ratio of PABZ to Cl-PBOA was 2:3. All of the Cl-PBOA and 88.2% of the total mass of PABZ, i.e., 6.355 g, were added into the reaction kettle, and stirred at 30°C for 1 h under nitrogen protection;

[0115] According to the polymer material solid content of 3.5%, the theoretical total amount of terephthaloyl chloride (TPC) was calculated to be 16.305 g by reaction equation. 80% of the theoretical total amount of TPC was divided into 6 times for pre-polymerization, i.e., 2.174 g each time, and the feeding interval was 0.3 h, and the polymerization kettle was controlled at 30°C. After the TPC feeding was completed, the reaction was stirred for 0.3 h, and then the remaining 0.851 g of PABZ was added into the polymerization kettle, and stirred and dissolved at 30°C for 0.35 h.

[0116] 3.098 g of TPC was added into the polymerization kettle to 99% of its total mass, and stirred for 0.5 h to obtain an aromatic heterocyclic polyamide solution, and the sample was detected, and the kinetic viscosity was 247 million centipoise.

[0117] S2, same as example 1.

[0118] S3, same as example 1.

[0119] Comparative example 3 S1, 892 g of N,N-dimethylacetamide was added into the polymerization kettle, and then 32.4 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a LiCl content of 3.5%wt; The diamine monomers were weighed, of which PABZ was 16.245 g and Cl-PBOA was 5.257 g, and the molar ratio of PABZ to Cl-PBOA was 17:3. All of the Cl-PBOA and all of the PABZ were added into the reaction kettle, and stirred at 30°C for 1 h under nitrogen protection;

[0120] According to the solid content of 3.5% of the polymer material, the theoretical total amount of terephthaloyl chloride (TPC) was calculated to be 17.302 g by reaction equation. 99% of the theoretical total amount of TPC, i.e. 17.129 g, was put into the polymerization kettle for pre-polymerization, and the temperature of the polymerization kettle was controlled at 30℃; the stirring reaction was carried out for 2 h to obtain an aromatic heterocyclic polyamide solution, and sampling detection showed that the dynamic viscosity was 64,000 centipoises.

[0121] S2, the same as example 1.

[0122] S3, the same as example 1.

[0123] Comparative example 4 S1, 1289 g of N,N-dimethylacetamide was added into the polymerization kettle, and then 46.75 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a LiCl content of 3.5%wt; The diamine monomers were weighed, of which PABZ was 23.475 g and Cl-PBOA was 7.597 g, and the molar ratio of PABZ to Cl-PBOA was 17:3. All of the Cl-PBOA and 88.2% of the total mass of PABZ, i.e. 20.705 g, were added into the reaction kettle, and stirring was carried out at 30℃ for 1 h under nitrogen protection;

[0124] According to the solid content of 3.5% of the polymer material, the theoretical total amount of terephthaloyl chloride (TPC) was calculated to be 24.998 g by reaction equation. 80% of the theoretical total amount of TPC was divided into 6 times and added into the polymerization kettle for pre-polymerization, i.e. 3.333 g each time, and the feeding was carried out once every 0.3 h, and the temperature of the polymerization kettle was controlled at 5℃. After the feeding of TPC was completed, stirring reaction was carried out for 0.3 h, and then the remaining 2.770 g of PABZ was added into the polymerization kettle and stirring dissolution was carried out at 5℃ for 0.35 h.

[0125] 4.751 g of TPC was added into the polymerization kettle to 99% of the total mass, and stirring reaction was carried out for 0.5 h to obtain an aromatic heterocyclic polyamide solution, and sampling detection showed that the dynamic viscosity was 54,000 centipoises.

[0126] S2, the same as example 1.

[0127] S3, the same as example 1.

[0128] Comparative example 5 S1, 946 g of N,N-dimethylacetamide was added into the polymerization kettle, and then 28.38 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a LiCl content of 3%wt; The diamine monomers were weighed, wherein the molar ratio of PABZ, Cl-PBOA and PDA was 11:3:6. All of the Cl-PBOA, all of the PDA and 83.3% of the total mass of PABZ, i.e. 8.71 g, were added to the reaction kettle, and stirred at 40°C for 1 h under nitrogen protection;

[0129] According to the solid content of the polymer material of 3%, the theoretical total amount of terephthaloyl chloride (TPC) was calculated to be 17.212 g by reaction equation. 80% of the theoretical total amount of TPC was divided into three times to be added to the polymerization kettle for prepolymerization, i.e. 4.589 g each time, and the polymerization kettle was controlled at a temperature of 5°C. After the addition of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 1.747 g of PABZ was added to the polymerization kettle, and stirred and dissolved at 5°C for 0.35 h.

[0130] 3.27 g of TPC was added to the polymerization kettle to 99% of the total mass, and stirred for 1 h to obtain an aromatic heterocyclic polyamide solution, which was sampled and detected to have a kinetic viscosity of 63 million centipoise.

[0131] S2, the same as example 3.

[0132] S3, the same as example 3.

[0133] Comparative example 6 S1, 957 g of N,N-dimethylacetamide was added to the polymerization kettle, and then 28.71 g of anhydrous lithium chloride was added and stirred until completely dissolved to obtain a composite solvent with a LiCl content of 3%wt; The diamine monomers were weighed, wherein the molar ratio of PABZ, Cl-PBOA and PDA was 11:3:6. All of the Cl-PBOA, all of the PDA and 83.3% of the total mass of PABZ, i.e. 8.71 g, were added to the reaction kettle, and stirred at 40°C for 1 h under nitrogen protection;

[0134] According to the solid content of the polymer material of 3%, the theoretical total amount of terephthaloyl chloride (TPC) was calculated to be 17.212 g by reaction equation. 80% of the theoretical total amount of TPC was divided into three times to be added to the polymerization kettle for prepolymerization, i.e. 4.589 g each time, and the polymerization kettle was controlled at a temperature of 5°C. After the addition of TPC was completed, the reaction was stirred for 0.3 h, and then the remaining 1.747 g of PABZ was added to the polymerization kettle, and stirred and dissolved at 5°C for 0.35 h.

[0135] The reaction was stirred for 2 h to obtain an aromatic heterocyclic polyamide solution, which was sampled and detected to have a kinetic viscosity of 54 million centipoise.

[0136] S2, the same as example 3.

[0137] S3, the same as example 3.

[0138] The arylheterocyclic polyamide fibers prepared in the examples and comparative examples were tested for performance, and the test results are shown in Table 1.

[0139] Table 1 Modulus and strength test results of arylheterocyclic polyamides of examples and comparative examples

[0140] As can be seen from Table 1, the arylheterocyclic polyamides prepared by the high-temperature stepwise feeding polycondensation method of the present application have high strength and high modulus, wherein the tensile strength of the arylheterocyclic polyamide fiber of Example 5 is optimal and can reach 5.8 GPa, while maintaining a high modulus of 150 GPa; the modulus of the arylheterocyclic polyamide fiber of Example 9 is highest and can reach 246 GPa, while maintaining a high strength of 5.4 GPa. Compared with Comparative Examples 1-6 which do not use high-temperature stepwise feeding, the arylheterocyclic polyamide fibers prepared in the present application have higher tensile strength and higher modulus. In addition, the preparation method of the present application is suitable for the preparation of various high-mechanical-property heterocyclic aramid systems, and can effectively improve the modulus of the fiber while maintaining high strength, especially for systems containing rigid rod-shaped monomers.

[0141] Although the present application has been described in detail in the specification and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present application. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of protection claimed by the present application.

Claims

1. A method for preparing high-strength, high-modulus aromatic heterocyclic polyamide fibers, characterized in that, The preparation method comprises the following steps: S1, the diamine monomer and aromatic diacyl chloride monomer are added into a composite solvent in multiple steps to carry out polycondensation reaction, and an aromatic heterocyclic polyamide solution is obtained; The diamine monomer comprises a diamine monomer A containing a heterocyclic structure, a diamine monomer B with a rigid rod structure, and a diamine monomer C; The composite solvent is a DMAc solution of LiCl; S2, the aromatic heterocyclic polyamide solution is sequentially subjected to filtration and degassing to obtain a spinning dope, and the spinning dope is subjected to coagulation bath coagulation and plasticization stretching to obtain a nascent fiber; S3, the nascent fiber is subjected to washing, drying and heat treatment to obtain a high-strength and high-modulus aromatic heterocyclic polyamide fiber.

2. The production method according to claim 1, characterized by, In the step S1, the molar content of the diamine monomer A is 40-90%, the molar content of the diamine monomer B is 10-50%, and the content of the diamine monomer C is 0-50% in the diamine monomer; The molar ratio of the diamine monomer to the aromatic diacyl chloride monomer is 1:(0.98-1.02).

3. The preparation method according to claim 1, characterized in that, The step S1 specifically comprises the following steps: S11, anhydrous LiCl is dissolved in DMAc to prepare a composite solvent; S12, under the protection of nitrogen, the diamine monomer B, the diamine monomer C and 70-90% of the diamine monomer A in total mass are added into the composite solvent, and stirring and dissolution are carried out to obtain a first intermediate solution; S13, under the protection of nitrogen, 80-85% of the aromatic diacyl chloride monomer in total mass is added into the intermediate solution in multiple steps, and heating reaction is carried out under the protection of nitrogen to obtain a second intermediate solution; S14, the remaining diamine monomer A is dissolved in the second intermediate solution to obtain a precursor solution; S15, the remaining aromatic diacyl chloride monomer is stirred and reacted to obtain an aromatic heterocyclic polyamide solution.

4. The preparation method according to any one of claims 1-3, wherein The diamine monomer A is 2-(4-aminophenyl)-5-aminobenzimidazole; The diamine monomer B comprises at least one of 4,4'-(3,5-dihydrodiimidazo[4,5-b:4',5'-e]pyridine-2,6-diyl)bis(3-chloroaniline) and 4,4'-(benzo[1,2-d:5,4-d']bis(oxazole)-2,6-diyl)bis(3-chloroaniline); The diamine monomer C comprises any one of p-phenylenediamine, 2-chlorobenzene-1,4-diamine, 2-(4-aminophenyl)benzo[d]oxazole-5-amine, 5-amino-2-(5-aminobenzo[d]oxazol-2-yl)phenol, amino-N-(4-amino-phenyl)benzoyl, 4-amino-N-(4-amino-2-chlorophenyl)benzoyl and naphthalene-2,6-diamine (NA-PDA); The aromatic diacyl chloride monomer is terephthaloyl chloride.

5. The preparation method according to claim 3, characterized in that, The concentration of LiCl in the composite solvent is 2-8 wt%; In the step S12, the temperature is controlled to be 30-80℃, and the stirring time is 1-2h; In the step S13, the reaction temperature is 30-80℃, and the reaction time is 0.5-3h; In the step S14, the stirring time is 0.5-1h; In the step S15, the reaction time is 0.5-3h.

6. The method of claim 1, wherein, In the step S2, the kinetic viscosity of the spinning dope is 30-100 kilopoise. The mass concentration of the aromatic heterocyclic polyamide in the spinning dope is 3-6 wt%.

7. The preparation method according to claim 1, characterized in that, The coagulation bath in step S2 is a mixed solution of N,N-dimethylacetamide and water; wherein the volume ratio of N,N-dimethylacetamide to water is 1:1-7:

3. The stretching ratio of the plasticized stretching is 70-150%.

8. The method of claim 1, wherein, The temperature of the washing in step S3 is 60-100℃; and the temperature of the drying is 130-200℃.

9. The method of claim 1, wherein, The conditions of the heat treatment in step S3 are: The tension is 0.05-0.5 cN / dt, and the temperature is 400-500℃.

10. The high-strength and high-modulus aromatic heterocyclic polyamide fiber prepared by the preparation method in any one of claims 1-9.

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