Heteroaromatic polyamide fiber and preparation method thereof

Abstract

The invention discloses a heteroaromatic polyamide fiber and a preparation method thereof. The preparation method comprises the following steps: carrying out polymerization reaction on a raw material system comprising a diamine monomer containing a heterocyclic structure, an aromatic diacyl chloride monomer and a composite solvent to obtain an aromatic heterocyclic polyamide solution; mixing the heteroaromatic polyamide solution with Lewis acid to prepare a spinning solution; the spinning solution is subjected to gel spinning, gel filaments are obtained, the gel filaments enter a coagulating bath to be coagulated and plasticized and stretched, washing, drying and hot stretching are carried out, and the aromatic heterocyclic polyamide fiber is obtained. The heteroaromatic polyamide fiber prepared by the method is compact in structure and high in orientation degree, and the orientation degree is 0.92-0.97; the mechanical property is excellent, the tensile strength is 33-41 cN / dt, and the elongation at break is 4.2%-6.1%. Compared with traditional wet spinning, the method has the advantages of high spinning speed and high production efficiency, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance fiber materials and preparation thereof, in particular to an aromatic heterocyclic polyamide fiber and a preparation method thereof. Background Art

[0002] Heteroaromatic polyamide fiber, also known as heterocyclic aramid, is a type of para-aramid fiber containing an aromatic heterocyclic structure in the main chain. Due to its light weight, high temperature resistance, and flame retardancy, it is widely used in high-tech fields such as national defense, military industry, aerospace, and transportation.

[0003] At present, the preparation of traditional aromatic heterocyclic polyamide fibers mainly relies on wet spinning and dry-jet-wet spinning processes. Among them, the wet spinning process has relatively simple equipment requirements and is widely used, but it has a limited spinning speed (10-20m / min), resulting in low production efficiency; at the same time, the fibers produced by this process are prone to form skin-core heterogeneous structures and holes, resulting in low mechanical properties of the fibers. Although the dry-jet-wet spinning process has achieved an increase in spinning speed, it relies on solidification phase separation molding and still cannot avoid the defects of the skin-core heterogeneous structure, resulting in the final mechanical properties of the fibers still being low. With the increasing requirements for material performance in high-tech fields, aromatic heterocyclic polyamide fibers prepared by traditional processes can no longer meet the application needs of high-tech fields.

[0004] In recent years, gel spinning technology has attracted much attention in the field of high-performance fiber preparation due to its unique advantages. This technology dissolves a polymer in a suitable solvent to form a spinning solution, and induces gelation in a specific coagulation bath or air gap to obtain gel-state fibers. Since the molecular chains in the gel state have high mobility and can withstand a large stretching ratio, the orientation degree is significantly improved, which helps to prepare high-performance fibers with dense structure and small skin-core structure difference. The Chinese patent technology with publication number CN 112877813 A discloses coarse denier high-strength medium-modulus polyacrylonitrile-based carbon fibers and their preparation method. By adopting a dry-jet gel spinning method, the radial skin-core structure difference of large-diameter fibers is reduced, the formation of medium and large pores inside and on the surface of the fibers is avoided, the uniformity of the fiber skin-core structure is improved, the smoothness of the fiber surface is improved, the fiber surface defects are reduced, and the tensile strength of the carbon fibers is improved. However, there are currently no reports on the gel spinning method of aromatic heterocyclic polyamides.

[0005] Therefore, developing a new preparation method for aromatic heterocyclic polyamide fibers to overcome the limitations of traditional processes and improve the mechanical properties of aromatic heterocyclic polyamide fibers is an urgent problem to be solved. Summary of the Invention

[0006] The present invention provides a method for preparing aromatic heterocyclic polyamide fibers. The aromatic heterocyclic polyamide fibers prepared by the method have a dense structure, an orientation degree of 0.92-0.97, and a high orientation degree. The aromatic heterocyclic polyamide fibers have a tensile strength of 33-41 cN / dt, an elongation at break of 4.2%-6.1%, and excellent mechanical properties.

[0007] The present invention also provides an aromatic heterocyclic polyamide fiber, which is prepared by the above preparation method. Therefore, the aromatic heterocyclic polyamide fiber has a high degree of orientation and excellent mechanical properties.

[0008] A first aspect of the present invention provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0009] A raw material system including a diamine monomer containing a heterocyclic structure, an aromatic diacyl chloride monomer and a composite solvent is subjected to a polymerization reaction to obtain an aromatic heterocyclic polyamide solution;

[0010] mixing the aromatic heterocyclic polyamide solution and Lewis acid to prepare a spinning solution;

[0011] The spinning solution is subjected to gel spinning treatment to obtain gel filaments. The gel filaments are placed in a coagulation bath for coagulation and plasticization stretching, and then washed, dried and heat stretched to obtain the aromatic heterocyclic polyamide fibers.

[0012] The preparation method of the aromatic heterocyclic polyamide fiber as described above, wherein the diamine monomer containing a heterocyclic structure is a diamine monomer containing an imidazole ring and a pyridine ring, or a diamine monomer containing an imidazole ring and a pyridine ring and an aromatic diamine monomer;

[0013] The molar ratio of the heterocyclic diamine monomer to the aromatic diacyl chloride monomer is 1:(0.98-1.02).

[0014] In the preparation method of the aromatic heterocyclic polyamide fiber as described above, when the diamine monomer containing a heterocyclic structure is a diamine monomer containing an imidazole ring and a pyridine ring and an aromatic diamine monomer, the molar proportion of the diamine monomer containing an imidazole ring and a pyridine ring in the diamine monomer containing a heterocyclic structure is greater than or equal to 30%.

[0015] The preparation method of the aromatic heterocyclic polyamide fiber as described above, wherein the diamine monomer containing an imidazole ring and a pyridine ring is at least one of 2-(4-aminopyridine)-5-aminobenzimidazole and 2-(4-aminophenyl)-5-aminopyridimidazole;

[0016] and / or the aromatic diamine monomer is at least one of 2-(4-aminophenyl)-5-aminobenzimidazole, p-phenylenediamine, 2-chloro-4-aminoaniline, 4,4'-diphenylenediamine, 4,4'-diaminobenzanilide, and 3,4'-diphenyletherdiamine;

[0017] And / or, the aromatic diacyl chloride monomer is at least one of terephthaloyl chloride and 2,6-naphthalene dicarboxylic acid chloride.

[0018] The method for preparing the aromatic heterocyclic polyamide fiber as described above, wherein the dynamic viscosity of the spinning solution is 100-1000 Pa·s;

[0019] And / or, the orientation degree of the aromatic heterocyclic polyamide fiber is 0.92-0.97.

[0020] In the above-mentioned method for preparing aromatic heterocyclic polyamide fibers, in the gel spinning process, the spinning speed is 30-100 m / min and the temperature is 40-100°C.

[0021] The method for preparing the aromatic heterocyclic polyamide fiber as described above, wherein the coagulation bath is a mixed solution made of N,N-dimethylacetamide and water; in the mixed solution, the volume ratio of N,N-dimethylacetamide to water is (30%-50%): (70%-50%);

[0022] And / or, the stretching ratio of the plasticizing stretching is 70%-150%;

[0023] And / or, the temperature of the thermal stretching is 380-450° C., and the tension is 0.05-0.3 cN / dt.

[0024] The method for preparing the aromatic heterocyclic polyamide fiber as described above, wherein the mass concentration of the aromatic heterocyclic polyamide in the spinning solution is 3%-5.7%, and the mass content of the Lewis acid is 0.5%-2%;

[0025] And / or, the Lewis acid is at least one of hydrochloric acid, nitric acid, oxalic acid, cupric chloride, and ferric chloride.

[0026] In the above-mentioned preparation method of aromatic heterocyclic polyamide fibers, the composite solvent is prepared by configuring a polar aprotic organic solvent and an inorganic salt cosolvent, and the mass concentration of the inorganic salt cosolvent in the composite solvent is 3% to 8%.

[0027] The second aspect of the present invention provides an aromatic heterocyclic polyamide fiber, which is prepared by the preparation method of the aromatic heterocyclic polyamide fiber.

[0028] The solution of the present invention has at least the following effects:

[0029] The present invention provides a method for preparing aromatic heterocyclic polyamide fibers. By using the C=N groups of benzimidazole and pyridine in the aromatic heterocyclic polyamide in the spinning solution to synergistically complex Lewis acids, the spinning solution undergoes a sol-gel transition during gel spinning, prompting the spinning solution to transition to a gel state, forming gel strands. The gel strands are then subjected to high-fold plasticization stretching (stretching ratio of 70%-150%), significantly improving the orientation of the aromatic heterocyclic polyamide fibers. Furthermore, when the gel strands pass through a coagulation bath, no significant solid-liquid phase separation occurs, reducing the skin-core heterogeneous structure. The prepared aromatic heterocyclic polyamide fibers have a denser and more uniform structure and superior mechanical properties. Compared with traditional wet spinning, the present invention has the advantages of faster spinning speed and higher production efficiency, making it suitable for industrial production.

[0030] The aromatic heterocyclic polyamide fiber provided by the present invention has an orientation degree of 0.92-0.97, a tensile strength of 33-41 cN / dt, and an elongation at break of 4.2%-6.1%. It has high orientation and excellent mechanical properties and has broad application prospects in high-tech fields such as national defense and military industry, bulletproof protection, aerospace, and transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is a physical picture of the spinning solution being ejected from the spinneret of the spinneret in Example 1;

[0033] Figure 2 This is a photo of the finished fiber obtained after the aromatic heterocyclic polyamide fiber in Example 1 is wound;

[0034] Figure 3 The sol-gel transition behavior of the spinning solution during the heating process in Example 1;

[0035] Figure 4 2D wide-angle diffraction test results of the aromatic heterocyclic polyamide fiber in Example 1;

[0036] Figure 5 This is the SEM image of the aromatic polyamide fiber in Example 1. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with embodiments of the present invention. Obviously, the described embodiments are part of embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific techniques or conditions are not indicated in the embodiments, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not indicate manufacturers are conventional products that can be obtained commercially.

[0038] In the following description, the term "and / or" is used to describe the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural.

[0039] Those skilled in the art should understand that in the following description of the embodiments of the present invention, the order of serial numbers 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 invention.

[0040] It will be understood by those skilled in the art that the numerical ranges in the embodiments of the present invention are to be understood as also specifically disclosing each intermediate value between the upper and lower limits of the ranges. Each smaller range between any stated value or intermediate value within a stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded within the range.

[0041] Unless defined otherwise, technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0042] The preparation of traditional aromatic heterocyclic polyamide fibers as pointed out in the background technology mainly relies on wet spinning and dry-jet-wet spinning processes. Among them, the wet spinning process has relatively simple equipment requirements and is widely used, but it has a limited spinning speed (10-20m / min), resulting in low production efficiency; at the same time, the fibers produced by this process are prone to form skin-core heterogeneous structures and holes, resulting in low mechanical properties of the fibers. Although the dry-jet-wet spinning process has achieved an increase in spinning speed, it needs to rely on solidification phase separation molding, and it still cannot avoid the defects of the skin-core heterogeneous structure, resulting in the final fiber mechanical properties are still low.

[0043] Based on this, in a first aspect, the present invention provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0044] A raw material system including a diamine monomer containing a heterocyclic structure, an aromatic diacyl chloride monomer and a composite solvent is subjected to a polymerization reaction to obtain an aromatic heterocyclic polyamide solution;

[0045] mixing the aromatic heterocyclic polyamide solution and Lewis acid to prepare a spinning solution;

[0046] The spinning solution is subjected to gel spinning treatment to obtain gel filaments. The gel filaments are placed in a coagulation bath for coagulation and plasticization stretching, and then washed, dried and heat stretched to obtain the aromatic heterocyclic polyamide fibers.

[0047] The present invention does not impose any particular limitation on the specific sources of the raw materials and reagents for preparing the aromatic heterocyclic polyamide fiber. The raw materials and reagents can be purchased from commercial sources or prepared according to methods known in the art.

[0048] In the present invention, the specific steps of subjecting the spinning solution to gel spinning include: degassing, filtering, and metering the spinning solution in a storage tank to a spinneret, and then spraying the solution through the spinneret's spinneret orifice into a hot tunnel for gel spinning.

[0049] The object of the present invention is to prepare aromatic heterocyclic polyamide fibers. Specifically, a raw material system including a diamine monomer containing a heterocyclic structure, an aromatic diacyl chloride monomer and a composite solvent is first subjected to a polymerization reaction to obtain an aromatic heterocyclic polyamide solution; then the aromatic heterocyclic polyamide solution and a Lewis acid are evenly mixed to obtain a Lewis acid aromatic heterocyclic polyamide spinning solution, i.e., a spinning solution having a dynamic viscosity; the spinning solution is degassed, filtered and metered in a storage tank and then fed to a spinneret, and then ejected from the spinneret through a spinneret orifice into a hot tunnel for gel spinning, so that the spinning solution undergoes a sol-gel transition behavior to obtain gel filaments; the gel filaments are placed in a coagulation bath for coagulation and plasticization stretching, and then washed, dried and hot stretched to finally obtain aromatic heterocyclic polyamide fibers with a high degree of orientation and excellent mechanical properties.

[0050] In this method, when the gel filaments enter the coagulation bath for coagulation and plasticization and stretching, no significant solid-liquid phase separation occurs, reducing the sheath-core heterogeneity. The resulting aromatic heterocyclic polyamide fibers have a dense and uniform structure, high orientation, and excellent mechanical properties. Compared with traditional wet spinning, this method has the advantages of faster spinning speed and higher production efficiency, making it suitable for industrial production.

[0051] In a specific embodiment, the diamine monomer containing a heterocyclic structure is a diamine monomer containing an imidazole ring and a pyridine ring, or a diamine monomer containing an imidazole ring and a pyridine ring and an aromatic diamine monomer;

[0052] The molar ratio of the heterocyclic diamine monomer to the aromatic diacyl chloride monomer is 1:(0.98-1.02).

[0053] For example, the molar ratio of the heterocyclic diamine monomer to the aromatic diacid chloride monomer may be any one of 1:0.98, 1:0.99, 1:1, 1:1.01, and 1:1.02, or any two of the above.

[0054] In one specific embodiment, when the heterocyclic diamine monomer is an imidazole- and pyridine-containing diamine monomer or an aromatic diamine monomer, the molar proportion of the imidazole- and pyridine-containing diamine monomer in the heterocyclic diamine monomer is greater than or equal to 30%. The imidazole- and pyridine-containing diamine monomer can form a stable complex with a Lewis acid and undergo a sol-gel transition when heated (during the gel spinning process).

[0055] In a specific embodiment, the diamine monomer containing an imidazole ring and a pyridine ring is at least one of 2-(4-aminopyridine)-5-aminobenzimidazole and 2-(4-aminophenyl)-5-aminopyridimidazole.

[0056] The structural formula of the above-mentioned 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ) is shown in formula (1), and the structural formula of the above-mentioned 2-(4-aminophenyl)-5-aminopyridinimidazole (PABZN) is shown in formula (2):

[0057]

[0058] When the diamine monomer containing imidazole rings and pyridine rings is the above-mentioned substance, the aromatic heterocyclic polyamide solution obtained by the polymerization reaction contains benzimidazole and pyridine. The C=N of benzimidazole and pyridine can synergistically complex Lewis acid to produce the above-mentioned spinning solution with dynamic viscosity, which is beneficial to the final preparation of aromatic heterocyclic polyamide fibers with high orientation and excellent mechanical properties.

[0059] The present invention does not particularly limit the specific preparation method of the above-mentioned diamine monomer containing an imidazole ring and a pyridine ring, and can be prepared according to methods known in the art. For example, the above-mentioned 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ) can be prepared according to the method in the reference (Synthesis of polyimides with lower H2O-absorption and higher thermal properties by incorporation of intramolecular H-bonding, J Polym Sci. 2020; 58: 969-976.).

[0060] In a specific embodiment, the aromatic diamine monomer is at least one of 2-(4-aminophenyl)-5-aminobenzimidazole, p-phenylenediamine, 2-chloro-4-aminoaniline, 4,4'-diphenylenediamine, 4,4'-diaminobenzanilide, and 3,4'-diphenyletherdiamine.

[0061] The structural formula of the above-mentioned 2-(4-aminophenyl)-5-aminobenzimidazole (PABZ) is shown in formula (3), the structural formula of the above-mentioned p-phenylenediamine (PDA) is shown in formula (4), the structural formula of the above-mentioned 2-chloro-4-aminoaniline (Cl-PDA) is shown in formula (5), the structural formula of the above-mentioned 4,4'-diphenylenediamine (Bz) is shown in formula (6), the structural formula of the above-mentioned 4,4'-diaminobenzanilide (DABA) is shown in formula (7), and the structural formula of the above-mentioned 3,4'-diphenyl ether diamine (3,4'-ODA) is shown in formula (8):

[0062]

[0063] Formula (8)

[0064] In a specific embodiment, the aromatic diacyl chloride monomer is at least one of terephthaloyl chloride and 2,6-naphthalene dicarboxylic acid chloride.

[0065] The structural formula of the above-mentioned terephthaloyl chloride (TPC) is shown in formula (9), and the structural formula of 2,6-naphthalene dicarboxylic acid chloride (NAPC) is shown in formula (10):

[0066]

[0067] In a specific embodiment, the dynamic viscosity of the spinning solution is 100-1000 Pa·s.

[0068] When the dynamic viscosity of the spinning solution is within the above range, the solution has good spinnability.

[0069] Illustratively, the dynamic viscosity of the spinning solution may be any one of 100 Pa·s, 200 Pa·s, 300 Pa·s, 400 Pa·s, 500 Pa·s, 600 Pa·s, 700 Pa·s, 800 Pa·s, 900 Pa·s, and 1000 Pa·s, or a range consisting of any two of the range.

[0070] In a specific embodiment, the orientation degree of the aromatic heterocyclic polyamide fiber is 0.92-0.97.

[0071] In a specific embodiment, in the gel spinning process, the spinning speed is 30-100 m / min and the temperature is 40-100°C.

[0072] When the spinning speed parameter is within the above range during the gel spinning process, it has the advantages of fast spinning speed and high production efficiency; when the temperature parameter is within the above range, the above spinning solution undergoes sol-gel transition behavior to form gel filaments, which is beneficial to the subsequent preparation of aromatic heterocyclic polyamide fibers with dense and uniform structure, high orientation and excellent mechanical properties.

[0073] Illustratively, in the gel spinning process, the spinning speed may be any one of 30 m / min, 40 m / min, 50 m / min, 60 m / min, 70 m / min, 80 m / min, 90 m / min, and 100 m / min, or a range consisting of any two of them; and the temperature may be any one of 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C, or a range consisting of any two of them.

[0074] In a specific embodiment, the coagulation bath is a mixed solution made of N,N-dimethylacetamide and water; in the mixed solution, the volume ratio of N,N-dimethylacetamide to water is (30%-50%): (70%-50%).

[0075] When the mixed solution is used as a component of the coagulation bath, the gel filaments are coagulated and plasticized and stretched in the coagulation bath to generate primary fibers with a dense and uniform structure.

[0076] For example, in the mixed solution, the volume ratio of N,N-dimethylacetamide to water can be any one of 30%:70%, 35%:65%, 40%:60%, 45%:55%, 50%:50%, or any two of the above.

[0077] In a specific embodiment, the stretching ratio of the plasticizing stretching is 70%-150%.

[0078] When the plasticizing stretching ratio is within the above range, the gel filaments enter the coagulation bath for coagulation and high-magnification plasticizing stretching (stretching ratio is 70%-150%), which is beneficial to improving the orientation degree and obtaining aromatic heterocyclic polyamide fibers with high orientation degree.

[0079] Illustratively, the stretching ratio of the plasticizing stretching may be any one of 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, or a range consisting of any two of these.

[0080] In a specific embodiment, the temperature of the thermal stretching is 380-450° C., and the tension is 0.05-0.3 cN / dt.

[0081] When the parameters of the temperature and tension of the thermal stretching are respectively within the above ranges, the mechanical properties of the prepared fiber are optimal.

[0082] Illustratively, the temperature of the above-mentioned hot stretching is any one of 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, and 450°C, or a range consisting of any two of them; the tension can be any one of 0.05 cN / dt, 0.1 cN / dt, 0.15 cN / dt, 0.2 cN / dt, 0.25 cN / dt, and 0.3 cN / dt, or a range consisting of any two of them.

[0083] In a specific embodiment, in the spinning solution, the mass concentration of the aromatic heterocyclic polyamide is 3%-5.7%, and the mass content of the Lewis acid is 0.5%-2%.

[0084] When the mass concentration of the aromatic heterocyclic polyamide and the mass content of the Lewis acid in the spinning solution are respectively within the above-mentioned ranges, the C=N of the benzimidazole and pyridine in the aromatic heterocyclic polyamide can fully synergistically complex the Lewis acid to produce a spinning solution with dynamic viscosity. Subsequently, the spinning solution undergoes a sol-gel transition behavior during the gel spinning process (i.e., the spinning solution is prompted to transition to a gel state) to form gel filaments. When the gel filaments enter the coagulation bath for coagulation and plasticization stretching, no obvious solid-liquid phase separation occurs, thereby weakening the skin-core heterogeneous structure, which is conducive to the final production of aromatic heterocyclic polyamide fibers with high orientation and excellent mechanical properties.

[0085] In a specific embodiment, the Lewis acid is at least one of hydrochloric acid (HCl), nitric acid (HNO3), oxalic acid, copper chloride (CuCl2), and ferric chloride (FeCl3).

[0086] In a specific embodiment, the composite solvent is prepared from a polar aprotic organic solvent and an inorganic salt co-solvent, and the mass concentration of the inorganic salt co-solvent in the polar aprotic organic solvent is 3% to 8%.

[0087] In the present invention, the polar aprotic organic solvent is a conventional type. Preferably, the polar aprotic organic solvent is at least one of N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), N,N'-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0088] In the present invention, the inorganic salt co-solvent is a conventional type. Preferably, the inorganic salt co-solvent is at least one of lithium chloride, calcium chloride, and lithium bromide.

[0089] In some embodiments, the spinning solution further comprises an organic solvent. Specifically, the spinning solution is prepared by mixing an aromatic heterocyclic polyamide solution, a Lewis acid, and an organic solvent.

[0090] The organic solvent is a conventional one. For example, the organic solvent may be at least one of N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and N,N'-dimethylformamide (DMF).

[0091] In a second aspect, the present invention provides an aromatic heterocyclic polyamide fiber produced by the aforementioned method for preparing aromatic heterocyclic polyamide fibers. Research by the inventors has shown that the aromatic heterocyclic polyamide fiber produced by this method exhibits an orientation of 0.92-0.97, a tensile strength of 33-41 cN / dt, and an elongation at break of 4.2%-6.1%. This fiber exhibits high orientation and excellent mechanical properties, and has broad application prospects in high-tech fields such as national defense, ballistic protection, aerospace, and transportation.

[0092] The present invention is further described below through specific examples.

[0093] The hydrochloric acid (HCl) used in the following examples is 37% wt HCl, purchased from Chengdu Kelong Chemical Co., Ltd.; the nitric acid (HNO3) is 65% wt HNO3, purchased from Chengdu Kelong Chemical Co., Ltd.

[0094] Example 1

[0095] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0096] (1) Preparation of heterocyclic polyamide solution

[0097] In a nitrogen-filled reactor, 21.27 g of 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ) was dissolved in 800 g of a DMAC / LiCl composite solvent, and 19.28 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0098] The molar ratio of PyPABZ to TPC is 1:1;

[0099] The DMAC / LiCl composite solvent is prepared by uniformly mixing N,N-dimethylacetamide (DMAC) and lithium chloride (LiCl), and the mass concentration of LiCl is 3.5%.

[0100] (2) Preparation of spinning solution

[0101] 8.3 g of hydrochloric acid was added to 20 g of DMAC and mixed uniformly to prepare HCl / DMAC, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring uniformly, a spinning solution of aromatic heterocyclic polyamide complexed with HCl was obtained, i.e., a spinning solution having a dynamic viscosity of 530 Pa·s.

[0102] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.9%, and the mass content of HCl is 1%.

[0103] (3) Preparation of aromatic polyamide fibers

[0104] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0105] During the gel spinning process, the spinning speed was controlled at 35 m / min, the temperature of the hot tunnel was 50° C., and the time of passing through the hot tunnel was 2 s.

[0106] The stretching ratio of the plasticizing stretching is 150%, the temperature of the thermal stretching is 400° C., and the tension of the thermal stretching is 0.1 cN / dt;

[0107] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0108] Figure 1 This is a physical picture of the spinning solution being ejected from the spinneret of the spinneret in Example 1; Figure 2 This is a photo of the finished fiber obtained after the aromatic heterocyclic polyamide fiber in Example 1 is wound.

[0109] Example 2

[0110] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0111] (1) Preparation of heterocyclic polyamide solution

[0112] In a nitrogen-filled reactor, 19.33 g of 2-(4-aminophenyl)-5-aminopyridimidazole (PABZN) and 6.21 g of p-phenylenediamine (PDA) were dissolved in 830 g of a DMAC / LiCl composite solvent, and 28.9 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0113] The ratio of the total molar number of the above-mentioned PABZN and PDA to the molar number of TPC is 1:0.99;

[0114] The molar proportion of PABZN in PABZN and PDA is 60%;

[0115] The DMAC / LiCl composite solvent is prepared by uniformly mixing N,N-dimethylacetamide (DMAC) and lithium chloride (LiCl), and the mass concentration of LiCl is 3%.

[0116] (2) Preparation of spinning solution

[0117] 4.8 g of hydrochloric acid (HCl) was added to 20 g of DMAC and mixed uniformly to prepare HCl / DMAC, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring uniformly, a spinning solution of aromatic heterocyclic polyamide complexed with HCl was obtained, i.e., a spinning solution having a dynamic viscosity of 828 Pa·s.

[0118] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 4.84%, and the mass content of HCl is 0.53%.

[0119] (3) Preparation of aromatic polyamide fibers

[0120] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0121] During the gel spinning process, the spinning speed was controlled at 55 m / min, the temperature of the hot tunnel was 65°C, and the time of passing through the hot tunnel was 3 s.

[0122] The stretching ratio of the plasticizing stretching is 120%, the temperature of the thermal stretching is 420° C., and the tension of the thermal stretching is 0.2 cN / dt;

[0123] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 40%:60%.

[0124] Example 3

[0125] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0126] (1) Preparation of heterocyclic polyamide solution

[0127] In a nitrogen-filled reactor, 6.25 g of 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ), 9.05 g of 2-(4-aminophenyl)-5-aminobenzimidazole (PABZ), and 3.51 g of 2-chloro-4-aminoaniline (Cl-PDA) were dissolved in 951.7 g of NMP / CaCl2 co-solvent, and 18.49 g of terephthaloyl chloride (TPC) was added to carry out polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0128] The ratio of the total molar number of the above-mentioned PyPABZ, PABZ and Cl-PDA to the molar number of TPC is 1:0.98;

[0129] The molar proportion of the above-mentioned PyPABZ in PyPABZ, PABZ and Cl-PDA is 30%;

[0130] The NMP / CaCl2 composite solvent is prepared by uniformly mixing N-methylpyrrolidone (NMP) and calcium chloride (CaCl2), and the mass concentration of CaCl2 is 7%.

[0131] (2) Preparation of spinning solution

[0132] 7 g of hydrochloric acid (HCl) was added to 30 g of NMP and mixed uniformly to prepare HCl / NMP, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring uniformly, a spinning solution of aromatic heterocyclic polyamide complexed with HCl was obtained, i.e., a spinning solution having a dynamic viscosity of 1000 Pa·s.

[0133] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3%, and the mass content of HCl is 0.7%.

[0134] (3) Preparation of aromatic polyamide fibers

[0135] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0136] During the gel spinning process, the spinning speed was controlled at 80 m / min, the temperature of the hot tunnel was 78° C., and the time of passing through the hot tunnel was 2.5 s.

[0137] The stretching ratio of the plasticizing stretching is 70%, the temperature of the hot stretching is 450° C., and the tension of the hot stretching is 0.3 cN / dt;

[0138] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 50%:50%.

[0139] Example 4

[0140] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0141] (1) Preparation of heterocyclic polyamide solution

[0142] In a nitrogen-filled reactor, 17.69 g of 2-(4-aminophenyl)-5-aminopyridimidazole (PABZN) and 6.26 g of 4,4'-diphenylenediamine (Bz) were dissolved in 850 g of a DMSO / LiBr composite solvent, and 23.2 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0143] The ratio of the total molar number of the above-mentioned PABZN and Bz to the molar number of TPC is 1:1.01;

[0144] The molar proportion of the above-mentioned PABZN in PABZN and Bz is 70%;

[0145] The DMSO / LiBr composite solvent is prepared by uniformly mixing dimethyl sulfoxide (DMSO) and lithium bromide (LiBr), and the mass concentration of LiBr is 8%.

[0146] (2) Preparation of spinning solution

[0147] 18.54 g of nitric acid (HNO3) was added to 30 g of DMSO and mixed evenly to prepare HNO3 / DMSO, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, a spinning solution of aromatic heterocyclic polyamide complexed with HNO3 was obtained, i.e., a spinning solution having a dynamic viscosity of 460 Pa·s.

[0148] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 4.08%, and the mass content of HNO3 is 2%.

[0149] (3) Preparation of aromatic polyamide fibers

[0150] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0151] In the gel spinning process, the spinning speed was controlled to be 100 m / min, the temperature of the hot tunnel was 100° C., and the time of passing through the hot tunnel was 1 s.

[0152] The stretching ratio of the plasticizing stretching is 110%, the temperature of the hot stretching is 380° C., and the tension of the hot stretching is 0.05 cN / dt;

[0153] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 30%:70%.

[0154] Example 5

[0155] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0156] (1) Preparation of heterocyclic polyamide solution

[0157] In a nitrogen-filled reactor, 15.21 g of 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ) and 3.85 g of 4,4'-diaminobenzanilide (DABA) were dissolved in 770 g of a DMF / LiCl composite solvent, and 17.06 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0158] The ratio of the total molar number of the above-mentioned PyPABZ and DABA to the molar number of TPC is 1:0.99;

[0159] The molar proportion of the above-mentioned PyPABZ in PyPABZ and DABA is 80%;

[0160] The DMF / LiCl composite solvent is prepared by uniformly mixing N,N'-dimethylformamide (DMF) and lithium chloride (LiCl), and the mass concentration of LiCl is 5%.

[0161] (2) Preparation of spinning solution

[0162] 6.3 g of ferric chloride (FeCl3) was added to 30 g of DMF and mixed uniformly to prepare FeCl3 / DMF, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring uniformly, a spinning solution of aromatic heterocyclic polyamide complexed with FeCl3 was obtained, i.e., a spinning solution having a dynamic viscosity of 100 Pa·s.

[0163] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.6%, and the mass content of FeCl3 is 0.72%.

[0164] (3) Preparation of aromatic polyamide fibers

[0165] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0166] During the gel spinning process, the spinning speed was controlled at 45 m / min, the temperature of the hot tunnel was 50° C., and the time of passing through the hot tunnel was 5 s.

[0167] The stretching ratio of the plasticizing stretching is 90%, the temperature of the hot stretching is 430° C., and the tension of the hot stretching is 0.15 cN / dt;

[0168] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 40%:60%.

[0169] Example 6

[0170] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0171] (1) Preparation of heterocyclic polyamide solution

[0172] In a nitrogen-filled reactor, 11.10 g of 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ), 2.35 g of 2-chloro-4-aminoaniline (Cl-PDA), and 3.31 g of 3,4'-diphenyl ether diamine (3,4'-ODA) were dissolved in 800 g of a DMF / CaCl2 composite solvent, and 16.77 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0173] The ratio of the total molar number of the above-mentioned PyPABZ, Cl-PDA and 3,4'-ODA to the molar number of TPC is 1:1;

[0174] The molar proportion of the above-mentioned PyPABZ in PyPABZ, Cl-PDA and 3,4′-ODA is 60%;

[0175] The DMF / CaCl2 composite solvent is prepared by uniformly mixing N,N'-dimethylformamide (DMF) and calcium chloride (CaCl2), and the mass concentration of CaCl2 is 6%.

[0176] (2) Preparation of spinning solution

[0177] 8.5 g of HCl was added to 30 g of DMF and mixed evenly to prepare HCl / DMF, which was then slowly added dropwise to the above aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, a spinning solution of aromatic heterocyclic polyamide complexed with HCl was obtained, i.e., a spinning solution having a dynamic viscosity of 610 Pa·s.

[0178] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.2%, and the mass content of HCl is 0.97%.

[0179] (3) Preparation of aromatic polyamide fibers

[0180] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0181] During the gel spinning process, the spinning speed was controlled at 35 m / min, the temperature of the hot tunnel was 55° C., and the time of passing through the hot tunnel was 4 s.

[0182] The stretching ratio of the plasticizing stretching is 125%, the temperature of the hot stretching is 430° C., and the tension of the hot stretching is 0.1 cN / dt;

[0183] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0184] Example 7

[0185] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0186] (1) Preparation of heterocyclic polyamide solution

[0187] In a nitrogen-filled reactor, 28.53 g of 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ) was dissolved in 800 g of a DMAC / LiCl composite solvent, and 32.34 g of 2,6-naphthalene dicarboxylic acid chloride (NAPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0188] The molar ratio of PyPABZ to NAPC is 1:0.995;

[0189] The DMAC / LiCl composite solvent is prepared by uniformly mixing DMAC and LiCl, and the mass concentration of LiCl is 4%.

[0190] (2) Preparation of spinning solution

[0191] 10 g of oxalic acid was added to 30 g of DMAC and mixed uniformly to prepare oxalic acid / DMAC, which was then slowly added dropwise to the above-mentioned heterocyclic polyamide solution using a constant pressure funnel. After stirring uniformly, a spinning solution of the heterocyclic polyamide complexed with oxalic acid was obtained, i.e., a spinning solution having a dynamic viscosity of 750 Pa·s.

[0192] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 5.7%, and the mass content of oxalic acid is 1.1%.

[0193] (3) Preparation of aromatic polyamide fibers

[0194] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0195] During the gel spinning process, the spinning speed was controlled at 35 m / min, the temperature of the hot tunnel was 65° C., and the time of passing through the hot tunnel was 3 s.

[0196] The stretching ratio of the plasticizing stretching is 130%, the temperature of the hot stretching is 420° C., and the tension of the hot stretching is 0.15 cN / dt;

[0197] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0198] Example 8

[0199] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0200] (1) Preparation of heterocyclic polyamide solution

[0201] In a nitrogen-filled reactor, 10.01 g of 2-(4-aminopyridine)-5-aminobenzimidazole (PyPABZ) and 10.01 g of 2-(4-aminophenyl)-5-aminopyridinoimidazole (PABZN) were dissolved in 852 g of a DMAC / LiCl composite solvent, and 22.39 g of 2,6-naphthalene dicarboxylic acid chloride (NAPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0202] The ratio of the total molar number of PyPABZ and PABZN to the molar number of NAPC is 1:0.99;

[0203] The DMAC / LiCl composite solvent is prepared by uniformly mixing DMAC and LiCl, and the mass concentration of LiCl is 3%.

[0204] (2) Preparation of spinning solution

[0205] 12.8 g of copper chloride (CuCl2) was added to 30 g of DMAC and mixed evenly to prepare CuCl2 / DMAC, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, a spinning solution of aromatic heterocyclic polyamide complexed with CuCl2 was obtained, i.e., a spinning solution having a dynamic viscosity of 390 Pa·s.

[0206] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.8%, and the mass content of CuCl2 is 1.5%.

[0207] (3) Preparation of aromatic polyamide fibers

[0208] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0209] During the gel spinning process, the spinning speed was controlled at 40 m / min, the temperature of the hot tunnel was 45°C, and the time of passing through the hot tunnel was 3 s.

[0210] The stretching ratio of the plasticizing stretching is 110%, the temperature of the thermal stretching is 440° C., and the tension of the thermal stretching is 0.1 cN / dt;

[0211] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 35%:65%.

[0212] Example 9

[0213] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0214] (1) Preparation of heterocyclic polyamide solution

[0215] In a nitrogen-filled reactor, 14.72 g of 2-(4-aminophenyl)-5-aminopyridimidazole (PABZN) and 4.43 g of 3,4'-diphenyl ether diamine (3,4'-ODA) were dissolved in 850 g of a DMAC / LiBr composite solvent, and 22.37 g of 2,6-naphthalene dicarboxylic acid chloride (NAPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0216] The ratio of the total molar number of the above-mentioned PABZN and 3,4'-ODA to the molar number of NAPC is 1:1;

[0217] The molar proportion of the above-mentioned PABZN in PABZN and 3,4'-ODA is 75%;

[0218] The DMAC / LiBr mixed solvent is prepared by uniformly mixing DMAC and LiBr, and the mass concentration of LiBr is 5%.

[0219] (2) Preparation of spinning solution

[0220] 8.3 g of copper chloride (CuCl2) was added to 30 g of DMAC and mixed evenly to prepare CuCl2 / DMAC, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, a spinning solution of aromatic heterocyclic polyamide complexed with CuCl2 was obtained, i.e., a spinning solution having a dynamic viscosity of 630 Pa·s.

[0221] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.7%, and the mass content of CuCl2 is 0.9%.

[0222] (3) Preparation of aromatic polyamide fibers

[0223] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0224] During the gel spinning process, the spinning speed was controlled at 45 m / min, the temperature of the hot tunnel was 50° C., and the time of passing through the hot tunnel was 2 s.

[0225] The stretching ratio of the plasticizing stretching is 100%, the temperature of the thermal stretching is 420° C., and the tension of the thermal stretching is 0.2 cN / dt;

[0226] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 40%:60%.

[0227] Example 10

[0228] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0229] (1) Preparation of heterocyclic polyamide solution

[0230] In a nitrogen-filled reactor, 11.44 g of 2-(4-aminophenyl)-5-aminopyridinimidazole (PABZN), 11.44 g of 2-(4-aminophenyl)-5-aminobenzimidazole (PABZ), and 5.0 g of 4,4'-diphenylenediamine (Bz) were dissolved in 880 g of a DMAC / LiCl composite solvent, and 29.66 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0231] The ratio of the total molar number of the above-mentioned PABZN, PABZ and Bz to the molar number of TPC is 1:1;

[0232] The molar proportion of the above-mentioned PABZN in PABZ, PABZN and Bz is 42.5%;

[0233] The DMAC / LiCl mixed solvent is prepared by uniformly mixing DMAC and LiCl, and the mass concentration of LiCl is 4.5%.

[0234] (2) Preparation of spinning solution

[0235] 10 g of HCl was added to 30 g of DMAC and mixed evenly to prepare HCl / DMAC, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, a spinning solution of aromatic heterocyclic polyamide complexed with HCl was obtained, i.e., a spinning solution having a dynamic viscosity of 870 Pa·s.

[0236] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 4.8%, and the mass content of HCl is 0.85%.

[0237] (3) Preparation of aromatic polyamide fibers

[0238] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0239] During the gel spinning process, the spinning speed was controlled to be 30 m / min, the temperature of the hot tunnel was 50° C., and the time of passing through the hot tunnel was 2 s.

[0240] The stretching ratio of the plasticizing stretching is 120%, the temperature of the hot stretching is 420° C., and the tension of the hot stretching is 0.05 cN / dt;

[0241] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 50%:50%.

[0242] Example 11

[0243] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0244] (1) The preparation of the aromatic heterocyclic polyamide solution is the same as in Example 1.

[0245] (2) Preparation of spinning solution

[0246] 8.3 g of ferric chloride (FeCl3) was added to 20 g of DMAC and mixed evenly to prepare FeCl3 / DMAC, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, a spinning solution of aromatic heterocyclic polyamide complexed with FeCl3 was obtained, i.e., a spinning solution having a dynamic viscosity of 580 Pa·s.

[0247] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.9%, and the mass content of FeCl3 is 1.7%.

[0248] (3) Preparation of aromatic polyamide fibers

[0249] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0250] During the gel spinning process, the spinning speed was controlled to be 75 m / min, the temperature of the hot tunnel was 55° C., and the time of passing through the hot tunnel was 1 s.

[0251] The stretching ratio of the plasticizing stretching is 140%, the temperature of the hot stretching is 420° C., and the tension of the hot stretching is 0.15 cN / dt;

[0252] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0253] Example 12

[0254] This embodiment provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0255] (1) The preparation of the aromatic heterocyclic polyamide solution is the same as that in Example 2.

[0256] (2) Preparation of spinning solution

[0257] 12 g of HCl was added to 30 g of DMAC and mixed evenly to prepare HCl / DMAC, which was then slowly added dropwise to the above-mentioned aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, a spinning solution of aromatic heterocyclic polyamide complexed with HCl was obtained, i.e., a spinning solution having a dynamic viscosity of 786 Pa·s.

[0258] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 4.81%, and the mass content of HCl is 1.3%.

[0259] (3) Preparation of aromatic polyamide fibers

[0260] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for gel spinning to obtain gel filaments. The gel filaments are then fed into a coagulation bath for coagulation and plasticization stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0261] During the gel spinning process, the spinning speed was controlled at 55 m / min, the temperature of the hot tunnel was 65°C, and the time of passing through the hot tunnel was 3 s.

[0262] The stretching ratio of the plasticizing stretching is 135%, the temperature of the hot stretching is 420° C., and the tension of the hot stretching is 0.1 cN / dt;

[0263] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 35%:65%.

[0264] Comparative Example 1

[0265] This comparative example provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0266] (1) Preparation of heterocyclic polyamide solution

[0267] In a nitrogen-filled reactor, 21.27 g of 2-(4-aminophenyl)-5-aminopyridinimidazole (PABZN) was dissolved in 800 g of a DMAC / LiCl composite solvent, and 19.28 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0268] The molar ratio of the above-mentioned PABZN to TPC is 1:1;

[0269] The DMAC / LiCl mixed solvent is prepared by uniformly mixing DMAC and LiCl, and the mass concentration of LiCl is 3.5%.

[0270] (2) Preparation of spinning solution

[0271] 28.3 g of DMAC was slowly added dropwise to the above aromatic heterocyclic polyamide solution using a constant pressure funnel, and stirred evenly to obtain an aromatic heterocyclic polyamide spinning solution having a dynamic viscosity of 510 Pa·s;

[0272] In the above aromatic heterocyclic polyamide spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.9%.

[0273] (3) Preparation of aromatic polyamide fibers

[0274] The spinning solution is degassed, filtered, and metered in a storage tank before being fed to a spinneret. The solution is then ejected from the spinneret's spinneret into a hot tunnel for spinning to obtain filaments. The filaments are then fed into a coagulation bath for coagulation, plasticization, and stretching, followed by washing, drying, and hot stretching to obtain aromatic heterocyclic polyamide fibers.

[0275] In the above spinning process, the spinning speed was controlled to be 35 m / min, the temperature of the hot tunnel was 50°C, and the time of passing through the hot tunnel was 2 s;

[0276] The stretching ratio of the plasticizing stretching is 150%, the temperature of the thermal stretching is 400° C., and the tension of the thermal stretching is 0.1 cN / dt;

[0277] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0278] Comparative Example 2

[0279] This comparative example provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0280] (1) Preparation of heterocyclic polyamide solution

[0281] In a nitrogen-filled reactor, 21.27 g of 2-(4-aminophenyl)-5-aminopyridinimidazole (PABZN) was dissolved in 800 g of a DMAC / LiCl composite solvent, and 19.28 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0282] The molar ratio of the above-mentioned PABZN to TPC is 1:1;

[0283] The DMAC / LiCl mixed solvent is prepared by uniformly mixing DMAC and LiCl, and the mass concentration of LiCl is 3.5%.

[0284] (2) Preparation of spinning solution

[0285] 8.3 g of HCl was added to 20 g of DMAC and mixed evenly to prepare HCl / DMAC. The HCl / DMAC was then slowly added dropwise to the above aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, an aromatic heterocyclic polyamide spinning solution complexed with HCl was obtained. The dynamic viscosity of the spinning solution was 530 Pa·s.

[0286] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.9%, and the mass content of HCl is 1%.

[0287] (3) Preparation of aromatic polyamide fibers

[0288] The spinning solution is subjected to a wet spinning process, specifically comprising: degassing, filtering, and metering the spinning solution in a storage tank before being fed to a spinneret, and extruding the solution through a spinneret orifice to obtain a filament; the filament is then fed into a coagulation bath for coagulation and plasticization stretching, and then washed, dried, and heat-stretched to obtain aromatic heterocyclic polyamide fibers;

[0289] During the above spinning process, the spinning speed was controlled to be 10 m / min;

[0290] The stretching ratio of the plasticizing stretching is 100%, the temperature of the thermal stretching is 400° C., and the tension of the thermal stretching is 0.1 cN / dt;

[0291] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0292] Comparative Example 3

[0293] This comparative example provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0294] (1) Preparation of heterocyclic polyamide solution

[0295] In a nitrogen-filled reactor, 21.27 g of 2-(4-aminophenyl)-5-aminobenzimidazole (PABZ) was dissolved in 800 g of a DMAC / LiCl composite solvent, and 19.28 g of terephthaloyl chloride (TPC) was added to carry out a polymerization reaction to obtain an aromatic heterocyclic polyamide solution.

[0296] The molar ratio of the above PABZ to TPC is 1:1;

[0297] The DMAC / LiCl mixed solvent is prepared by uniformly mixing DMAC and LiCl, and the mass concentration of LiCl is 3.5%.

[0298] (2) Preparation of spinning solution

[0299] 8.3 g of HCl was added to 20 g of DMAC and mixed evenly to prepare HCl / DMAC. The HCl / DMAC was then slowly added dropwise to the above aromatic heterocyclic polyamide solution using a constant pressure funnel. After stirring evenly, an aromatic heterocyclic polyamide spinning solution complexed with HCl was obtained. The dynamic viscosity of the spinning solution was 530 Pa·s.

[0300] In the spinning solution, the mass concentration of aromatic heterocyclic polyamide is 3.9%, and the mass content of HCl is 1%.

[0301] (3) Preparation of aromatic polyamide fibers

[0302] The spinning solution is subjected to a wet spinning process, specifically comprising: degassing, filtering, and metering the spinning solution in a storage tank before being fed to a spinneret, and extruding the solution through a spinneret orifice to obtain a filament; the filament is then fed into a coagulation bath for coagulation and plasticization stretching, and then washed, dried, and heat-stretched to obtain aromatic heterocyclic polyamide fibers;

[0303] During the above spinning process, the spinning speed was controlled to be 10 m / min;

[0304] The stretching ratio of the plasticizing stretching is 100%, the temperature of the thermal stretching is 400° C., and the tension of the thermal stretching is 0.1 cN / dt;

[0305] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0306] Comparative Example 4

[0307] This comparative example provides a method for preparing aromatic heterocyclic polyamide fibers, comprising the following steps:

[0308] (1) The preparation of the aromatic heterocyclic polyamide solution is the same as in Example 1.

[0309] (2) The spinning solution was prepared in the same manner as in Example 1.

[0310] (3) Preparation of aromatic polyamide fibers

[0311] The spinning solution is subjected to a wet spinning process, specifically comprising: degassing, filtering, and metering the spinning solution in a storage tank before being fed to a spinneret, and extruding the solution through a spinneret orifice to obtain a filament; the filament is then fed into a coagulation bath for coagulation and plasticization stretching, and then washed, dried, and heat-stretched to obtain aromatic heterocyclic polyamide fibers;

[0312] During the above spinning process, the spinning speed was controlled to be 10 m / min;

[0313] The stretching ratio of the plasticizing stretching is 150%, the temperature of the thermal stretching is 400° C., and the tension of the thermal stretching is 0.1 cN / dt;

[0314] The coagulation bath is a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 45%:55%.

[0315] Performance Testing

[0316] 1. The spinning solution in Example 1 was heated at 50°C. Figure 3 shown.

[0317] Depend on Figure 3 It can be seen that the spinning solution undergoes sol-gel transition behavior during the heating process.

[0318] 2. The aromatic polyamide fiber in Example 1 was subjected to a two-dimensional wide-angle diffraction test. Figure 4 shown.

[0319] Depend on Figure 4 It can be seen that the molecular chains of the aromatic heterocyclic polyamide are highly oriented along the fiber axis.

[0320] 3. Scanning electron microscope (SEM) test was performed on the aromatic heterocyclic polyamide fiber in Example 1. Figure 5 shown.

[0321] Depend on Figure 5 It can be seen that the structure of aromatic polyamide fibers is dense and uniform.

[0322] 4. The following tests were performed on the aromatic polyamide fibers in Examples 1-12 and Comparative Examples 1-4, respectively. The test results are shown in Table 1.

[0323] The orientation degree was measured by two-dimensional wide-angle diffraction, and the half-peak width (H) was calculated by azimuthal integration. The orientation degree was calculated by the half-peak width; orientation degree = (180°-H) / 180°;

[0324] The breaking strength and elongation at break were tested using the Q91510132587572760X·001-2018 standard, with a tensile rate of 25.4 mm / min and a spacing of 170 mm.

[0325] Table 1 Test results

[0326] project Orientation Breaking strength (cN / dt) Elongation at break (%) Example 1 0.97 36.3 4.9 Example 2 0.96 40.1 5.3 Example 3 0.93 33.0 4.2 Example 4 0.92 33.7 4.4 Example 5 0.95 40.5 4.8 Example 6 0.97 41.0 6.1 Example 7 0.96 37.8 5.2 Example 8 0.93 38.9 5.1 Example 9 0.94 38.3 5.7 Example 10 0.93 37.9 4.7 Example 11 0.95 34.8 5.4 Example 12 0.94 35.7 5.1 Comparative Example 1 0.89 32.6 4.0 Comparative Example 2 0.87 31.8 3.9 Comparative Example 3 0.85 30.2 3.7 Comparative Example 4 0.88 32.8 3.9

[0327] As shown in Table 1, the aromatic heterocyclic polyamide fibers produced using the method of the present invention exhibit a degree of orientation of 0.92-0.97, a tensile strength of 33-41 cN / dt, and an elongation at break of 4.2%-6.1%, demonstrating high orientation and excellent mechanical properties. Compared to Comparative Examples 1-4, the aromatic heterocyclic polyamide fibers produced using the method of the present invention exhibit higher orientation and superior mechanical properties.

[0328] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing aromatic heterocyclic polyamide fiber, characterized in that: The following steps are involved: A raw material system including a diamine monomer containing a heterocyclic structure, an aromatic diacyl chloride monomer and a composite solvent is subjected to a polymerization reaction to obtain an aromatic heterocyclic polyamide solution; mixing the aromatic heterocyclic polyamide solution and Lewis acid to prepare a spinning solution; The spinning solution is subjected to gel spinning treatment to obtain gel filaments. The gel filaments are placed in a coagulation bath for coagulation and plasticization stretching, and then washed, dried and heat stretched to obtain the aromatic heterocyclic polyamide fibers.

2. The method for preparing aromatic heterocyclic polyamide fiber according to claim 1, characterized in that: The diamine monomer containing a heterocyclic structure is a diamine monomer containing an imidazole ring and a pyridine ring, or a diamine monomer containing an imidazole ring and a pyridine ring and an aromatic diamine monomer; The molar ratio of the heterocyclic diamine monomer to the aromatic diacyl chloride monomer is 1:(0.98-1.02).

3. The method for preparing aromatic heterocyclic polyamide fiber according to claim 2, characterized in that: When the heterocyclic diamine monomer is an imidazole ring- and pyridine ring-containing diamine monomer or an aromatic diamine monomer, the molar proportion of the imidazole ring- and pyridine ring-containing diamine monomer in the heterocyclic diamine monomer is greater than or equal to 30%.

4. The method for preparing aromatic heterocyclic polyamide fiber according to claim 2, characterized in that: The diamine monomer containing an imidazole ring and a pyridine ring is at least one of 2-(4-aminopyridine)-5-aminobenzimidazole and 2-(4-aminophenyl)-5-aminopyridimidazole; and / or the aromatic diamine monomer is at least one of 2-(4-aminophenyl)-5-aminobenzimidazole, p-phenylenediamine, 2-chloro-4-aminoaniline, 4,4'-diphenylenediamine, 4,4'-diaminobenzanilide, and 3,4'-diphenyletherdiamine; And / or, the aromatic diacyl chloride monomer is at least one of terephthaloyl chloride and 2,6-naphthalene dicarboxylic acid chloride.

5. The method for preparing aromatic heterocyclic polyamide fiber according to claim 1, characterized in that: The dynamic viscosity of the spinning solution is 100-1000 Pa·s; And / or, the orientation degree of the aromatic heterocyclic polyamide fiber is 0.92-0.

97.

6. The method for preparing aromatic heterocyclic polyamide fiber according to claim 1, characterized in that: In the gel spinning process, the spinning speed is 30-100 m / min and the temperature is 40-100°C.

7. The method for preparing aromatic heterocyclic polyamide fiber according to claim 1, characterized in that: The coagulation bath is a mixed solution made of N,N-dimethylacetamide and water; in the mixed solution, the volume ratio of N,N-dimethylacetamide to water is (30%-50%): (70%-50%); And / or, the stretching ratio of the plasticizing stretching is 70%-150%; And / or, the temperature of the thermal stretching is 380-450° C., and the tension is 0.05-0.3 cN / dt.

8. The method for preparing aromatic heterocyclic polyamide fiber according to claim 1, characterized in that: In the spinning solution, the mass concentration of the aromatic heterocyclic polyamide is 3%-5.7%, and the mass content of the Lewis acid is 0.5%-2%; And / or, the Lewis acid is at least one of hydrochloric acid, nitric acid, oxalic acid, cupric chloride, and ferric chloride.

9. The method for preparing aromatic heterocyclic polyamide fiber according to claim 1, characterized in that: The composite solvent is prepared by mixing a polar aprotic organic solvent and an inorganic salt co-solvent. The mass concentration of the inorganic salt co-solvent in the composite solvent is 3% to 8%.

10. An aromatic heterocyclic polyamide fiber, characterized in that: The aromatic heterocyclic polyamide fiber is prepared by the preparation method of any one of claims 1 to 9.

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