High-strength high-temperature-resistant polyamide fiber and preparation method thereof

Abstract

The invention provides a high-strength high-temperature-resistant polyamide fiber and a preparation method thereof, and belongs to the technical field of polyamide industrial yarns. In the aspect of a polyamide structure, the block copolymerized polyamide prepolymer can combine the characteristics of a rigid chain segment and a flexible chain segment, and cooperative improvement of processability and high performance of polyamide is realized through control of a sequence structure; the random copolymerized polyamide prepolymer containing meta-aryl and / or phenylate amine in the structure can reduce the viscous flow activation energy of the semi-aromatic polyamide, so that the semi-aromatic polyamide has better melt spinnability. In the aspect of polyamide fiber forming, a porous aerial fog spraying gradient cooling system is used for reducing defects in nascent fibers, the draft multiple limitation of a traditional process is broken through through multi-stage draft induction, a high-orientation and high-crystallization condensed state structure is constructed, and the strength of the polyamide fibers is further improved; the polyarmide fiber is endowed with the characteristics of high strength, high heat resistance and high toughness through the multi-stage structural design from a chemical structure to a condensed state structure.

Description

Technical Field

[0001] The present invention relates to the technical field of polyamide industrial yarns, and in particular to a high-strength and high-temperature resistant polyamide fiber and a preparation method thereof. Background Art

[0002] As a polymer material with excellent comprehensive performance, polyamide fiber has shown important application value in the fields of aerospace, national defense and military industry, and deep-sea exploration. Its lightweight characteristics can significantly reduce the structural weight of spacecraft recovery systems, special protective equipment and deep-sea equipment, while maintaining sufficient mechanical strength and impact resistance, making it an ideal choice to replace traditional high-density materials. In the aerospace field, this material is used for large parachutes and landing cushioning devices; in the aviation field, it is used as a high-performance tire reinforcement material to improve the safety factor; in the deep-sea field, it is used for mooring systems that serve for a long time under dynamic load environments. However, with the development of extreme equipment working conditions, the problem of insufficient heat resistance of existing polyamide fibers has become increasingly prominent, making it difficult to meet the long-term stability requirements under high temperature and high pressure environments, seriously restricting its application expansion in scenarios such as aircraft engine peripheral components and deep-sea hydrothermal area detection equipment.

[0003] In recent years, the development of semi-aromatic polyamides has provided a new approach to improving heat resistance, but the inherent inversion between its high melting point and thermal decomposition temperature leads to a narrow processing window, making it difficult to achieve fiber formation through conventional melt spinning. Although the melting temperature can be adjusted through copolymerization modification, the reduction in the proportion of rigid segments limits the effect of improving heat resistance, while the retention of high-rigidity segments leads to poor spinnability. This contradictory phenomenon exposes the inherent defects of traditional modification strategies: the optimization of a single performance often comes at the expense of other key properties, and it is impossible to achieve a synergistic improvement in strength, heat resistance and spinnability. Existing technologies have not yet solved the problem of compatibility between molecular chain structure design and processing technology, especially the negative impact of the introduction of rigid groups on the rheological behavior and orientation structure of the melt, which has become a core obstacle to the development of high-strength and heat-resistant polyamide fibers.

[0004] For example, CN102465353A discloses “a homopolymerized semi-aromatic polyamide fiber and a preparation method thereof”, which obtains semi-aromatic polyamide by copolymerizing aromatic polyamide units with aliphatic polyamide units, and prepares semi-aromatic polyamide fibers by melt spinning. However, due to its low fiber strength, its application in high-load scenarios is limited. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a high-strength and high-temperature resistant polyamide fiber and a preparation method thereof. The present invention can achieve a synergistic improvement in the mechanical strength and high-temperature resistance of the polyamide fiber while retaining melt spinnability.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for preparing high-strength and high-temperature resistant polyamide fiber, comprising the following steps: (1) Providing a polyamide prepolymer; the polyamide prepolymer includes a random copolymerized polyamide prepolymer and / or a block copolymerized polyamide prepolymer; the polyamide prepolymer has a semi-aromatic polyamide structure, and the random copolymerized polyamide prepolymer contains a meta-aromatic structural unit and / or a phenylene ether amine structural unit in its structure; (2) performing vacuum solid phase viscosity enhancement on the polyamide prepolymer to obtain a high temperature resistant polyamide resin; (3) mixing the high temperature resistant polyamide resin with an antioxidant, performing twin-screw melt mixing, spinneret extrusion and multi-porous aerosol spray gradient cooling to obtain spun fibers; the multi-porous aerosol spray gradient cooling comprises: At a distance of 0 to 10 cm from the spinneret, nitrogen cooling at a temperature of -30 to -20 °C was used; At a distance of 10-50 cm from the spinneret, atomized silicone oil with a temperature of 100-120°C is used for cooling; At a distance of 50-100 cm from the spinneret, hot air with a temperature of 80°C is used for cooling; (4) The spun fibers are subjected to spinneret drawing, temperature-stress coordinated multi-stage drawing, and multi-stage heat setting to obtain high-strength and high-temperature resistant polyamide fibers.

[0007] Preferably, the molecular weight of the polyamide prepolymer is 3000-8000 g / mol; The random copolymerized polyamide prepolymer has a structure shown in Formula 1: Formula 1; In formula 1, n = 0, 2, 5 or 6; x:y = 3~4:1; The block copolymer polyamide prepolymer has a structure shown in Formula 2: Formula 2; In formula 2, n = 0, 2, 5 or 6; w:v = 6~8:1; In Formula 1 and Formula 2, A and B are independently one or more of the following structures: A= 、 or ; B= 、 or .

[0008] Preferably, the preparation method of the random copolymerized polyamide prepolymer comprises the following steps: Mixing a diamine monomer, a diacid monomer, a catalyst, an antioxidant, a capping agent and water, and sequentially performing a salt-forming reaction and a polymerization reaction to obtain a random copolymer polyamide prepolymer; The polymerization reaction temperature is 250-270° C. and the pressure is 2-3 MPa.

[0009] Preferably, the method for preparing the block copolymer polyamide prepolymer comprises the following steps: Mixing the blocked first prepolymer and the blocked second prepolymer and performing melt polycondensation to obtain a block copolymer polyamide prepolymer; The end-capping groups of the first prepolymer and the second prepolymer are amino groups or carboxyl groups; and the preparation method of the first prepolymer or the second prepolymer comprises the following steps: The diamine monomer, the diacid monomer, the antioxidant and water are mixed and subjected to polycondensation reaction to obtain a prepolymer.

[0010] Preferably, the temperature of the vacuum solid phase thickening is 220-250°C, the pressure is 100-150 Pa, and the time is 6-12 hours; The high-temperature resistant polyamide resin has a melting point of 280-300° C., a molecular weight of 20,000-30,000 g / mol, and a melt flow index of 40-50 g / 10 min at 320° C.

[0011] Preferably, the mass of the antioxidant is 1-5% of the mass of the high temperature resistant polyamide resin; The temperature of the twin-screw melt mixing is 310-330°C.

[0012] Preferably, the drafting ratio of the spinneret is 30 to 50 times; The temperature-stress coordinated multi-stage drawing includes a primary drawing and a secondary drawing; The temperature of the first-stage drawing is 190-220°C, and the drawing ratio is 3.5-3.8 times; The temperature of the secondary drawing is 180-220° C., and the drawing ratio is 1.2-1.5 times.

[0013] Preferably, the multi-stage heat setting includes a first heat setting and a second heat setting; The first heat setting temperature is 190°C; The temperature of the second heat setting is 180-230°C.

[0014] The present invention provides high-strength and high-temperature resistant polyamide fibers prepared by the above preparation method.

[0015] Preferably, the polyamide fiber has a breaking strength of 10-12 cN / dtex, an elongation at break of 20-25%, and a strength retention rate of >95% after heat treatment at 200°C for 6 hours.

[0016] The present invention provides a method for preparing high-strength and high-temperature resistant polyamide fibers, comprising the following steps: (1) providing a polyamide prepolymer; the polyamide prepolymer comprises a random copolymerized polyamide prepolymer and / or a block copolymerized polyamide prepolymer; the polyamide prepolymer has a semi-aromatic polyamide structure, and the structure of the random copolymerized polyamide prepolymer contains an meta-aromatic structural unit and / or a phenylene ether amine structural unit; (2) subjecting the polyamide prepolymer to vacuum solid-phase viscosity enhancement to obtain a high-temperature resistant polyamide resin; (3) mixing the high-temperature resistant polyamide resin with an antioxidant, subjecting the mixture to twin-screw melt mixing, spinneret extrusion, and multi-hole aerosol spray gradient cooling to obtain spun fibers; and (4) subjecting the spun fibers to spinneret drawing, temperature-stress coordinated multi-stage drawing, and multi-stage heat setting to obtain high-strength and high-temperature resistant polyamide fibers.

[0017] In terms of polyamide structure, the present invention utilizes random copolymerized polyamide prepolymers and / or segmented copolymerized polyamide prepolymers having a semiaromatic polyamide structure as the polyamide prepolymer. The use of segmented copolymerized polyamide prepolymers in the present invention can better combine the characteristics of rigid and flexible segments. By controlling the sequence structure, the processability and high performance of the polyamide are synergistically improved, allowing it to maintain good mechanical properties and high-temperature resistance while maintaining good processability.

[0018] In addition, the present invention can also use a random copolymer polyamide prepolymer containing an meta-aromatic structural unit and / or a phenylene ether amine structural unit in its structure as a polyamide prepolymer. By introducing a large sterically hindered meta-aromatic ring structure and a flexible phenylene ether structure into the traditional semi-aromatic polyamide structure, the viscous flow activation energy of the semi-aromatic polyamide is reduced, so that it has better melt spinnability.

[0019] In the field of polyamide fiber formation, existing spinning processes for semi-aromatic polyamide fibers generally utilize a uniform cooling method (cross-blowing or ring-blowing), which fails to precisely control the structural differences between the sheath and core of the spun fiber. Due to the high rigidity of the semi-aromatic polyamide macromolecule chain and the significant viscoelasticity of the melt, traditional cooling processes during rapid prototyping can easily lead to the surface layer forming a loose structure dominated by amorphous structures due to sudden cooling, while the core forms coarse crystalline regions due to slow heat dissipation. This creates significant residual stress at the interface between the two due to differential thermal contraction. The present invention utilizes a multi-hole aerosol spray gradient cooling system to reduce defects in nascent fibers. Specifically, high-velocity cold nitrogen (-30°C to -20°C) is used to rapidly cool the surface layer near the spinneret (0-10 cm), forming a dense microcrystalline cortex. Contact cooling is performed in the central region (10-50 cm) using atomized silicone oil (100-120°C) to regulate slow crystallization in the core. In the distal region (50-100 cm), slow-rate hot air (80°C) is used to balance the cooling rate and eliminate residual stress. Furthermore, the present invention overcomes the draw ratio limitations of traditional processes through multi-stage drafting induction, constructing a highly oriented, highly crystalline condensed structure and further enhancing the strength of polyamide fibers. This multi-stage structural design, from chemical structure to condensed structure, imparts polyamide fibers with high strength, heat resistance, and toughness. The core innovation of this invention lies in achieving a triple breakthrough in polyamide fiber strength, heat resistance, and processability through controlled molecular chain sequence design and precise matching of process parameters, providing technical support for the industrial application of high-performance fiber materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the preparation method of the high-strength and high-temperature resistant polyamide fiber of the present invention. DETAILED DESCRIPTION

[0021] The present invention provides a method for preparing high-strength and high-temperature resistant polyamide fiber, comprising the following steps: (1) Providing a polyamide prepolymer; the polyamide prepolymer includes a random copolymerized polyamide prepolymer and / or a block copolymerized polyamide prepolymer; the polyamide prepolymer has a semi-aromatic polyamide structure, and the random copolymerized polyamide prepolymer contains a meta-aromatic structural unit and / or a phenylene ether amine structural unit in its structure; (2) performing vacuum solid phase viscosity enhancement on the polyamide prepolymer to obtain a high temperature resistant polyamide resin; (3) mixing the high temperature resistant polyamide resin with an antioxidant, performing twin-screw melt mixing, spinneret extrusion and multi-porous aerosol spray gradient cooling to obtain spun fibers; the multi-porous aerosol spray gradient cooling comprises: At a distance of 0 to 10 cm from the spinneret, nitrogen cooling at a temperature of -30 to -20 °C was used; At a distance of 10-50 cm from the spinneret, atomized silicone oil with a temperature of 100-120°C is used for cooling; At a distance of 50-100 cm from the spinneret, hot air with a temperature of 80°C is used for cooling; (4) The spun fibers are subjected to spinneret drawing, temperature-stress coordinated multi-stage drawing and heat setting to obtain high-strength and high-temperature resistant polyamide fibers.

[0022] The present invention first provides a polyamide prepolymer. In the present invention, the polyamide prepolymer comprises a random copolymerized polyamide prepolymer and / or a block copolymerized polyamide prepolymer; the polyamide prepolymer has a semi-aromatic polyamide structure, and the random copolymerized polyamide prepolymer contains meta-aromatic structural units and / or phenylene ether amine structural units. In the present invention, the random copolymerized polyamide prepolymer is preferably obtained by high-temperature solution polymerization; in the present invention, the preparation method of the random copolymerized polyamide prepolymer preferably comprises the following steps: A diamine monomer, a diacid monomer, a catalyst, an antioxidant, an end-capping agent, and water are mixed, and salt formation and polymerization reactions are sequentially performed to obtain a random copolymerized polyamide prepolymer. In the present invention, the diamine monomer preferably includes one or more of decanediamine, hexamethylenediamine, 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl ether; the diacid monomer preferably includes one or more of adipic acid, sebacic acid, terephthalic acid, and isophthalic acid; and the molar ratio of the diamine monomer to the diacid monomer is preferably 1.01 to 1.04:1.

[0023] In the present invention, the catalyst preferably comprises phosphoric acid, phosphorous acid, hypophosphorous acid, or a mixture of one or more of their metal salts or esters, more preferably sodium hypophosphite. In the present invention, the amount of the catalyst is preferably 0.1-0.5 wt % of the total weight of the monomers, more preferably 0.2-0.4 wt %.

[0024] In the present invention, the antioxidant preferably includes one or more of Antioxidant SEED, Antioxidant 1010, Antioxidant 1098, Antioxidant 168, and Antioxidant 1076, more preferably Antioxidant 1098 and Antioxidant SEED are compounded in a mass ratio of 1:1. In the present invention, the amount of the antioxidant is preferably 0.1-0.5wt% of the total weight of the monomers, more preferably 0.2-0.4wt%.

[0025] In the present invention, the end-capping agent preferably includes one or more of benzoic acid, terephthalic acid, adipic acid, sebacic acid and decanediamine. In the present invention, the amount of the end-capping agent is preferably 1 to 3 mol% of the total molar amount of the monomers.

[0026] In the present invention, the water is preferably deionized water. In the present invention, the mass ratio of all monomers to water is preferably 0.5-0.8:1, more preferably 0.6-0.7:1.

[0027] In the present invention, the salt-forming reaction is preferably carried out under nitrogen with stirring. The temperature of the salt-forming reaction is preferably 60-90°C, more preferably 70-80°C, and the time is preferably 1-3 hours, more preferably 2 hours. The heating rate to the temperature of the salt-forming reaction is preferably 5°C / min. In the present invention, during the salt-forming reaction, the diamine monomer and the diacid monomer form salts to produce aliphatic amide salts and aromatic amide salts. In the present invention, the mass fraction of the aliphatic amide salt is preferably 60-70%, more preferably 68%; the mass fraction of the aromatic amide salt is preferably 35%-45%, more preferably 37%.

[0028] In the present invention, the polymerization reaction temperature is preferably 250-270°C, and the pressure is preferably 2-3 MPa. In the present invention, the polymerization reaction is preferably stopped when the water output reaches 15 wt% of the total feed amount. After the polymerization reaction, the material is preferably flash-dissolved, and the resulting solid is pulverized and dried to obtain a random copolymerized polyamide prepolymer.

[0029] In the present invention, the molecular weight of the random copolymer polyamide prepolymer is preferably 5000-8000 g / mol, more preferably 6000-7000 g / mol; the random copolymer polyamide prepolymer has a structure shown in Formula 1: Formula 1; In formula 1, n = 0, 2, 5 or 6; x:y = 3~4:1; A and B are independently one or more of the following structures: A= 、 or ; B= 、 or ; That is, A and B are derived from one or more of the following structures: A comes from 、 or ; B comes from 、 or .

[0030] In the present invention, n in A and B is 0, 2, 5 or 6.

[0031] In the present invention, the block copolymer polyamide prepolymer is preferably prepared by a double-end prepolymer melt recombination method; the preparation method of the block copolymer polyamide prepolymer preferably comprises the following steps: The blocked first prepolymer and the blocked second prepolymer are mixed and melt-polycondensed to obtain a block copolymer polyamide prepolymer.

[0032] In the present invention, the end-capping groups of the first prepolymer and the second prepolymer are amino groups or carboxyl groups. In the present invention, the preparation method of the first prepolymer or the second prepolymer preferably comprises the following steps: The diamine monomer, the diacid monomer, the antioxidant and water are mixed and subjected to polycondensation reaction to obtain a prepolymer.

[0033] In the present invention, the diamine monomer preferably includes one or more of decanediamine, hexamethylenediamine, 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl ether; the diacid monomer preferably includes one or more of adipic acid, sebacic acid, terephthalic acid, and isophthalic acid; and the molar ratio of the diamine monomer to the diacid monomer is preferably 1-1.5:1-2. In the present invention, the mass of the water preferably accounts for 50-60% of the total mass of the diamine monomer and the diacid monomer; and the mass of the antioxidant preferably accounts for 0-1% of the total mass of the diamine monomer and the diacid monomer.

[0034] In the present invention, the polycondensation reaction is preferably carried out under a nitrogen atmosphere, the temperature of the polycondensation reaction is preferably 250° C., and the time is preferably 1.5 hours. In the present invention, after the polycondensation reaction, the polycondensation reaction system is preferably evacuated to remove small molecules. In the present invention, the vacuum degree of the evacuation is preferably 100 Pa, and the time is preferably 1 hour.

[0035] In the present invention, a first end-capped prepolymer and a second end-capped prepolymer are mixed and melt-polycondensed to obtain a block copolymer polyamide prepolymer. In the present invention, the melt-polycondensation is preferably carried out under vacuum conditions. The temperature of the melt-polycondensation is preferably 200-310°C, more preferably 280-300°C; the vacuum degree is preferably 50-100 Pa, more preferably 60-80 Pa; and the time is preferably 1-2 hours.

[0036] In the present invention, the molecular weight of the block copolymer polyamide prepolymer is preferably 3000-5000 g / mol, more preferably 3500-4500 g / mol; the block copolymer polyamide prepolymer has a structure shown in Formula 2: Formula 2; In formula 2, n = 0, 2, 5 or 6; w:v = 6~8:1; A and B are independently one or more of the following structures: A= 、 or ; B= 、 or ; That is, A and B are derived from one or more of the following structures: A comes from 、 、 One or more of the following; B comes from 、 、 One or more of the .

[0037] After obtaining the polyamide prepolymer, the present invention performs vacuum solid-phase thickening on the polyamide prepolymer to obtain a high-temperature resistant polyamide resin. In the present invention, the vacuum solid-phase thickening is preferably performed in a vacuum drying oven, and the temperature of the vacuum solid-phase thickening is preferably 220~250°C, more preferably 230~240°C; the pressure is preferably 100~150Pa, more preferably 120~140Pa; and the time is preferably 6~12h, more preferably 8~10h. The present invention can make the polyamide resin have a higher molecular weight and a narrower molecular weight distribution through the vacuum solid-phase thickening. The present invention can inhibit the thermal oxidative degradation of the polyamide resin during high-temperature processing through the vacuum solid-phase thickening, so that its yellowing index ΔYI is less than 2.5.

[0038] In the present invention, the melting point of the high temperature resistant polyamide resin is preferably 280-300° C., the molecular weight is 20,000-30,000 g / mol, and the melt flow index at 320° C. is preferably 40-50 g / 10 min.

[0039] After obtaining the high-temperature resistant polyamide resin, the present invention mixes the high-temperature resistant polyamide resin with an antioxidant, performs twin-screw melt mixing, spinneret extrusion, and porous aerosol spray gradient cooling to obtain spun fibers. In the present invention, the antioxidant preferably includes one or more of antioxidant SEED, antioxidant 1010, antioxidant 1098, antioxidant 168, and antioxidant 1076, more preferably antioxidant 1098 and antioxidant SEED are compounded in a mass ratio of 1:1. In the present invention, the mass of the antioxidant is preferably 1-5% of the mass of the high-temperature resistant polyamide resin, more preferably 1-3%.

[0040] In the present invention, the temperature of the twin-screw melt mixing (i.e., the spinning temperature) is preferably 310-330° C., more preferably 320° C. In the present invention, the porous aerosol spray gradient cooling includes: At a distance of 0 to 10 cm from the spinneret, nitrogen gas at a temperature of -30 to -20°C is used for cooling; the flow rate of the nitrogen gas is preferably 2 to 5 m / s, more preferably 3 to 4 m / s; At a distance of 10-50 cm from the spinneret, atomized silicone oil with a temperature of 100-120°C is used for cooling; At a distance of 50 to 100 cm from the spinneret, hot air with a temperature of 80° C. is used for cooling; the wind speed of the hot air is preferably 0.5 to 0.8 m / s; more preferably 0.6 to 0.7 m / s.

[0041] After obtaining the spun fibers, the present invention performs spinneret drawing, temperature-stress synergistic multi-stage drawing, and heat setting on the spun fibers to obtain high-strength, high-temperature-resistant polyamide fibers. In the present invention, the draw ratio of the spinneret drawing is preferably 30 to 50 times, more preferably 35 to 40 times; the drafting roller temperature of the spinneret drawing is preferably 100 to 150°C, and the rotation speed is preferably 500 to 600 m / min.

[0042] In the present invention, the temperature-stress coordinated multi-stage drawing preferably includes primary drawing and secondary drawing; the temperature of the primary drawing is preferably 190~220°C, more preferably 200~210°C; the drawing ratio is preferably 3.5~3.8 times, more preferably 3.6~3.7 times; the temperature of the secondary drawing is preferably 180~220°C, more preferably 190~200°C, and the drawing ratio is preferably 1.2~1.5 times, more preferably 1.3~1.4 times.

[0043] In the present invention, the multi-stage heat setting preferably includes a first heat setting and a second heat setting; the temperature of the first heat setting is 190-220°C, more preferably 200-210°C; the temperature of the second heat setting is preferably 180-230°C, more preferably 200-220°C.

[0044] The present invention provides a high-strength and high-temperature-resistant polyamide fiber prepared by the above-mentioned preparation method. In the present invention, the polyamide fiber has a breaking strength of 10-12 cN / dtex, an elongation at break of 20-25%, and a strength retention rate of >95% after heat treatment at 200°C for 6 hours.

[0045] The high-strength and high-temperature resistant polyamide fiber and the preparation method thereof provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] The preparation of high-strength and high-temperature resistant random copolyamide (PA6T-r-PA6I) fibers adopts the following steps: (1) The mass and proportion of each raw material are as follows: accurately weigh 10 mol of hexamethylenediamine, 7 mol of terephthalic acid and 3 mol of isophthalic acid, and 0.1 mol of benzoic acid, the amount of catalyst sodium hypophosphite and antioxidant (antioxidant SEED and antioxidant 1098 are compounded in a mass ratio of 1:1) is 0.1wt% of the total mass of diamine and diacid, and add 50wt% of deionized water.

[0048] (2) All the above raw materials were added to the polymerization kettle, and the temperature was increased at a heating rate of 5°C / min under a nitrogen atmosphere. Stirring was started at 90°C, the stirring rate was controlled at 50 rpm, and the stirring time was 1 hour to promote the salt formation of the diacid and diamine monomers in the solution.

[0049] (3) The temperature was further increased to 210°C at a heating rate of 5°C / min, and the pressure was increased to 2.2~2.5MPa. Appropriate exhaust was performed to maintain the pressure stable. After maintaining the temperature and pressure for 2h, the temperature was again increased to 250°C, and the pressure was adjusted to 2.5~3MPa. After maintaining the temperature and pressure for 1h, when the water output reached 15wt% of the total feed amount, the discharge valve was opened to flash-evaporate the material, which was then crushed and dried to obtain a semi-aromatic copolyamide prepolymer.

[0050] (4) The semi-aromatic copolyamide prepolymer is placed in a high-temperature drum oven, maintained at a temperature of 250°C and a pressure of 110 Pa, and after viscosity increasing for 6 hours, it is taken out and crushed to obtain a high-temperature resistant polyamide resin.

[0051] (5) The copolyamide resin was dried and mixed with antioxidant 1098 (addition amount: 1 wt%) and then added to the twin-screw extruder. The spinning temperature was set to 310 °C. The melt stream extruded from the spinneret was passed through a porous aerosol spray gradient cooling system to obtain nascent fibers. The nitrogen temperature of the near-spinneret (0-10 cm) plate area was set to -20 °C with a flow rate of 2 m / s. The temperature of the atomized silicone oil in the middle area (10-50 cm) was 100 °C. The temperature of the slow hot air in the far-spinneret area (50-100 cm) was 80 °C with a flow rate of 0.6 m / s.

[0052] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 35 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0053] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 210°C, the drawing ratio was 3.6 times, the secondary drawing temperature was 215°C, the drawing ratio was 1.5 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2500 m / min to obtain high-strength and high-temperature resistant random copolyamide (PA6T-r-PA6I) fiber.

[0054] Example 2

[0055] The preparation of high-strength and high-temperature resistant block copolyamide (PA10T-b-PAO10) fibers adopts the following steps: (1) When preparing the PA10T prepolymer, amino end-capping was used. During the actual polymerization process, the feed ratio of terephthalic acid to decanediamine was maintained at 1.2:1. Deionized water was used as the solvent, and the addition amount was 50wt% of the total mass of diamine and diacid. The polycondensation was carried out at 300℃ for 2h in a nitrogen atmosphere with a stirring rate of 50rpm. At the end of the reaction, the small molecules were removed by vacuum adjustment (100Pa) to obtain the PA10T prepolymer.

[0056] (2) 4,4'-Diaminodiphenyl ether was mixed with excess sebacic acid (acid:amine = 1.5:1, molar ratio), deionized water was used as the solvent, the addition amount was 50wt% of the total weight of the monomer, 1wt% of antioxidant 1098 was added, and polycondensation was carried out at 250°C in a nitrogen atmosphere for 1.5h. After removing small molecules at a vacuum degree of 110Pa for 1h, PAO10 prepolymer was obtained.

[0057] (3) The two prepolymers were put into a polymerization kettle in a mass ratio of (PA10T:PAO10=7:3), and 0.1wt% of sodium hypophosphite as a catalyst was added. The temperature was raised while stirring under a nitrogen atmosphere. The heating rate was controlled to be 5°C / min and the stirring rate was 25rpm. After the low-melting-point component melted, the stirring rate was increased to 50rpm. The mixture was melt-polycondensed at 290°C and a vacuum degree of 100Pa for 2h. Nitrogen was used to form a positive pressure discharge in the polymerization kettle. The mixture was pelletized after cooling.

[0058] (4) After the pellets are dried and cooled, they are placed in a high-temperature drum oven, maintained at a temperature of 250°C and a pressure of 100 Pa, and taken out after viscosity increasing for 10 hours to obtain a high-temperature resistant polyamide resin.

[0059] (5) After drying, the copolyamide resin and antioxidant 1098 (1 wt%) were added to the twin-screw extruder, and the spinning temperature was set to 315 °C. During the spinning process, the temperature fluctuation was controlled at ±5 °C. The melt stream extruded through the spinneret was subjected to gradient cooling. The nitrogen temperature in the near spinneret area (0-10 cm) was -20 °C and the flow rate was 3 m / s. The temperature of the atomized silicone oil in the middle area (10-50 cm) was 110 °C. The temperature of the slow hot air in the far spinneret area (50-100 cm) was 80 °C and the flow rate was 0.6 m / s to obtain the nascent fiber.

[0060] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 35 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0061] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 220°C, the drawing ratio was 3.6 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.4 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 220°C, the relaxation rate was 4%, and the final winding speed was 2500 m / min to obtain high-strength and high-temperature resistant block copolyamide (PA10T-b-PAO10) fiber.

[0062] Example 3

[0063] The preparation of high-strength and high-temperature resistant block copolyamide (PA10T-b-PA10I) fibers adopts the following steps: (1) Isophthalic acid and decanediamine were added to a polymerization reactor in a molar ratio of 1:1.5. After purging with nitrogen for 5 times, deionized water was used as a solvent in an amount of 50 wt% of the total mass of diamine and diacid. The mixture was polycondensed at 220 °C for 2 h in a nitrogen atmosphere with a stirring rate of 50 rpm. At the end of the reaction, the small molecules were removed by vacuum adjustment (100 Pa) to obtain PA10I prepolymer.

[0064] (2) When preparing PA10T prepolymer, carboxyl end-capping was used. During the actual polymerization process, the feed ratio of terephthalic acid to decanediamine was maintained at 1.2:1. Deionized water was used as the solvent, and the added amount was 50wt% of the total mass of diamine and diacid. Polycondensation was carried out at 300℃ for 2h in a nitrogen atmosphere. At the end of the reaction, the small molecules were removed by adjusting the vacuum degree (the vacuum degree was maintained at 100~120Pa) to obtain the carboxyl end-capped PA10T prepolymer.

[0065] (3) The two prepolymers were added into a polymerization kettle in a mass ratio of (PA10T:PA10I=7:3), heated and stirred under a nitrogen atmosphere, and the heating rate was controlled to be 5°C / min and the stirring rate was 15 rpm. After the low-melting-point component melted, the stirring rate was increased to 50 rpm. The mixture was melt-polycondensed at 310°C and a vacuum degree of 100 Pa for 2 h. Nitrogen was used to form a positive pressure discharge in the polymerization kettle, and the mixture was pelletized after cooling.

[0066] (4) The pellets were placed in a drum oven, maintained at a temperature of 250°C and a pressure of 110 Pa, and taken out after viscosity increasing for 12 hours to obtain a high-temperature resistant polyamide resin.

[0067] (5) After drying, the copolyamide resin and antioxidant 1098 (added at 1 wt%) were added to a twin-screw extruder. The spinning temperature was set at 310 °C. The melt stream extruded through the spinneret was subjected to gradient cooling. The temperature of the nitrogen near the spinneret (0-10 cm) was -20 °C and the flow rate was 3 m / s. The temperature of the atomized silicone oil in the middle zone (10-50 cm) was 110 °C. The temperature of the slow hot air in the far spinneret zone (50-100 cm) was 80 °C and the flow rate was 0.7 m / s to obtain the nascent fiber.

[0068] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 35 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0069] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 200°C, the drawing ratio was 3.5 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.5 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2450 m / min.

[0070] Example 4

[0071] The preparation of high-strength and high-temperature resistant random copolyamide (PA6T-r-O6) fiber adopts the following steps: (1) The mass and proportion of each raw material are as follows: accurately weigh 10 mol of terephthalic acid, 7 mol of hexamethylenediamine and 3 mol of 4,4'-diaminodiphenyl ether, and 0.1 mol of benzoic acid, the amount of catalyst sodium hypophosphite and antioxidant (antioxidant SEED and antioxidant 1098 are compounded in a mass ratio of 1:1) is 0.1wt% of the total mass of diamine and diacid, and 50wt% of deionized water is added.

[0072] (2) All the above raw materials were added to the polymerization kettle, and the temperature was increased at a heating rate of 5°C / min under a nitrogen atmosphere. Stirring was started at 80°C, the stirring rate was controlled at 50 rpm, and the stirring time was 1 hour to promote the salt formation of the diacid and diamine monomers in the solution.

[0073] (3) The temperature was further increased to 210°C at a heating rate of 5°C / min, and the pressure was increased to 2.2~2.5MPa. Appropriate exhaust was performed to maintain the pressure stable. After maintaining the temperature and pressure for 2h, the temperature was again increased to 250°C, and the pressure was adjusted to 2.5~3MPa. After maintaining the temperature and pressure for 1h, when the water output reached 15wt% of the total feed amount, the discharge valve was opened to flash-evaporate the material, which was then crushed and dried to obtain a semi-aromatic copolyamide prepolymer.

[0074] (4) The semi-aromatic copolyamide prepolymer is placed in a high-temperature drum oven, maintained at a temperature of 250°C and a pressure of 120 Pa, and taken out after viscosity increasing for 8 hours, and crushed to obtain a high-temperature resistant polyamide resin.

[0075] (5) The copolyamide resin was dried and mixed with antioxidant 1098 (added at 1 wt%) and then added to the twin-screw extruder. The spinning temperature was set at 310 °C. The melt stream extruded from the spinneret was passed through a porous aerosol spray gradient cooling system to obtain nascent fibers. The nitrogen temperature in the near-spinneret zone (0-10 cm) was set to -20 °C with a flow rate of 4 m / s. The temperature of the atomized silicone oil in the middle zone (10-50 cm) was set to 110 °C. The temperature of the slow hot air in the far-spinneret zone (50-100 cm) was set to 80 °C with a flow rate of 0.7 m / s.

[0076] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 40 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0077] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 210°C, the drawing ratio was 3.5 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.4 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2550 m / min to obtain high-strength and high-temperature resistant random copolyamide (PA6T-r-O6) fiber.

[0078] Example 5

[0079] The preparation of high-strength and high-temperature resistant random copolyamide (PA6T-r-PAO6) fibers adopts the following steps: (1) The mass and proportion of each raw material are as follows: accurately weigh 10 mol of hexamethylenediamine, 7 mol of terephthalic acid and 3 mol of 3,4'-diaminodiphenyl ether, and 0.1 mol of benzoic acid, the amount of catalyst sodium hypophosphite and antioxidant (SEED and antioxidant 1098 are compounded in a mass ratio of 1:1) is 0.1wt% of the total mass of diamine and diacid, and 50wt% of deionized water is added.

[0080] (2) All the above raw materials were added to the polymerization kettle, and the temperature was increased at a heating rate of 5°C / min under a nitrogen atmosphere. Stirring was started at 90°C, the stirring rate was controlled at 50 rpm, and the stirring time was 1 hour to promote the salt formation of the diacid and diamine monomers in the solution.

[0081] (3) The temperature was further increased to 210°C at a heating rate of 5°C / min, and the pressure was increased to 2.2~2.5MPa. Appropriate exhaust was performed to maintain the pressure stable. After maintaining the temperature and pressure for 2h, the temperature was again increased to 260°C, and the pressure was adjusted to 2.5~3MPa. After maintaining the temperature and pressure for 1h, when the water output reached 15wt% of the total feed amount, the discharge valve was opened to flash-evaporate the material, which was then crushed and dried to obtain a semi-aromatic copolyamide prepolymer.

[0082] (4) The semi-aromatic copolyamide prepolymer is placed in a high-temperature drum oven, maintained at a temperature of 250°C and a pressure of 100 Pa, and taken out after viscosity increasing for 8 hours, and crushed to obtain a high-temperature resistant polyamide resin.

[0083] (5) The copolyamide resin was dried and mixed with antioxidant 1098 (addition amount: 1 wt%) and then added to the twin-screw extruder. The spinning temperature was set to 320 °C. The melt stream extruded from the spinneret was passed through a porous aerosol spray gradient cooling system to obtain nascent fibers. The temperature of the nitrogen near the spinneret (0-10 cm) was set to -20 °C with a flow rate of 4 m / s. The temperature of the atomized silicone oil in the middle zone (10-50 cm) was set to 100 °C. The temperature of the slow hot air in the far spinneret zone (50-100 cm) was set to 80 °C with a flow rate of 0.6 m / s.

[0084] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 35 times. The temperature of the first collecting roller is 90 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0085] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 200°C, the drawing ratio was 3.6 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.5 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2500 m / min to obtain high-strength and high-temperature resistant random copolyamide (PA6T-r-PAO6) fiber.

[0086] Example 6

[0087] High-strength and heat-resistant segmented copolyamide (PA10T-b-PA1010) fiber (1) Sebacic acid and decanediamine were added to a polymerization reactor in a molar ratio of 1:1.4. After purging with nitrogen for 5 times, deionized water was used as a solvent in an amount of 50 wt% of the total mass of diamine and diacid. The reaction was carried out at 200 °C in a nitrogen atmosphere with a stirring rate of 50 rpm for 2 h. At the end of the reaction, the small molecules were removed by vacuum adjustment (100 Pa) to obtain PA1010 prepolymer.

[0088] (2) When preparing PA10T prepolymer, carboxyl end-capping was used. During the actual polymerization process, the feed ratio of terephthalic acid to decanediamine was maintained at 1.2:1. Deionized water was used as the solvent, and the added amount was 50wt% of the total mass of diamine and diacid. Polycondensation was carried out at 300℃ for 2h in a nitrogen atmosphere. At the end of the reaction, the small molecules were removed by adjusting the vacuum degree (the vacuum degree was maintained at 100~120Pa) to obtain the carboxyl end-capped PA10T prepolymer.

[0089] (3) The two prepolymers were added into a polymerization kettle in a mass ratio of (PA10T:PA1010=8:2), and the temperature was raised while stirring under a nitrogen atmosphere. The heating rate was controlled at 5°C / min and the stirring rate was 15 rpm. After the low-melting-point component melted, the stirring rate was increased to 50 rpm. The mixture was melt-polycondensed at 310°C and a vacuum degree of 100 Pa for 2 h. Nitrogen was used to form a positive pressure discharge in the polymerization kettle. The mixture was pelletized after cooling.

[0090] (4) The semi-aromatic copolyamide pellets were placed in a drum oven, maintained at a temperature of 250°C and a pressure of 150 Pa, and taken out after viscosity increasing for 9 hours to obtain a high-temperature resistant polyamide resin.

[0091] (5) After drying, the copolyamide resin and antioxidant 1098 (added at 1 wt%) were added to the twin-screw extruder. The spinning temperature was set at 310 °C. The melt stream extruded through the spinneret was subjected to gradient cooling. The temperature of the nitrogen near the spinneret (0-10 cm) was -20 °C, the temperature of the atomized silicone oil in the middle zone (10-50 cm) was 80 °C, and the temperature of the slow hot air far from the spinneret (50-100 cm) was 110 °C to obtain the nascent fiber.

[0092] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 35 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0093] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 200°C, the drawing ratio was 3.7 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.5 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2450 m / min.

[0094] Comparative Example 1

[0095] Conventional random copolyamide (PA6T-r-PA66) fiber (1) The mass and proportion of each raw material are as follows: accurately weigh 10 mol of hexamethylenediamine, 4.5 mol of terephthalic acid and 5.5 mol of adipic acid, and 0.1 mol of benzoic acid. The amount of catalyst sodium hypophosphite and antioxidant SEED is 0.1 wt% of the total mass of diamine and diacid, and add 50 wt% of deionized water.

[0096] (2) All the above raw materials were added to the polymerization kettle, and the temperature was increased at a heating rate of 5°C / min under a nitrogen atmosphere. Stirring was started at 90°C, the stirring rate was controlled at 50 rpm, and the stirring time was 1 hour to promote the salt formation of the diacid and diamine monomers in the solution.

[0097] (3) The temperature was further increased to 210°C at a heating rate of 5°C / min, and the pressure was increased to 2.2~2.5MPa. Appropriate exhaust was performed to maintain the pressure stable. After maintaining the temperature and pressure for 2h, the temperature was again increased to 250°C, and the pressure was adjusted to 2.5~3MPa. After maintaining the temperature and pressure for 1h, when the water output reached 15wt% of the total feed amount, the discharge valve was opened to flash-evaporate the material, which was then crushed and dried to obtain a semi-aromatic copolyamide prepolymer.

[0098] (4) The semi-aromatic copolyamide prepolymer is placed in a high-temperature drum oven, maintained at a temperature of 250°C and a pressure of 100 Pa, and taken out after viscosity increasing for 8 hours, and crushed to obtain a high-temperature resistant polyamide resin.

[0099] (5) After drying, the copolyamide resin and antioxidant 1098 (added at 1 wt%) were added to the twin-screw extruder, and the spinning temperature was set at 330 °C. The melt stream extruded through the spinneret was subjected to gradient cooling. The temperature of the nitrogen near the spinneret (0-10 cm) was -25 °C, and the flow rate was 5 m / s. The temperature of the atomized silicone oil in the middle zone (10-50 cm) was 80 °C. The temperature of the slow hot air in the far spinneret zone (50-100 cm) was 120 °C, and the flow rate was 0.8 m / s. The nascent fibers were obtained.

[0100] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 35 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0101] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 210°C, the drawing ratio was 3.5 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.5 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2400 m / min.

[0102] Comparative Example 2

[0103] (1) The mass and proportion of each raw material are as follows: accurately weigh 10 mol of hexamethylenediamine, 4.5 mol of terephthalic acid and 5.5 mol of isophthalic acid, and 0.1 mol of benzoic acid. The amount of catalyst sodium hypophosphite and antioxidant SEED is 0.1 wt% of the total mass of diamine and diacid, and add 50 wt% of deionized water.

[0104] (2) All the above raw materials were added to the polymerization kettle, and the temperature was increased at a heating rate of 5°C / min under a nitrogen atmosphere. Stirring was started at 90°C, the stirring rate was controlled at 50 rpm, and the stirring time was 1 hour to promote the salt formation of the diacid and diamine monomers in the solution.

[0105] (3) The temperature is further increased to 210°C at a heating rate of 5°C / min, and the pressure is increased to 2.2-2.5 MPa. Appropriate exhaust is performed to maintain the pressure stable. After maintaining the temperature and pressure for 2 hours, the temperature is again increased to 250°C, and the pressure is adjusted to 2.5-3 MPa. After maintaining this state for 1 hour, when the water output reaches 15 wt% of the total feed amount, the discharge valve is opened to flash-evaporate the material, which is then crushed and dried to obtain a semi-aromatic copolyamide prepolymer.

[0106] (4) The semi-aromatic copolyamide prepolymer is placed in a high-temperature rotary drum oven, maintained at a temperature of 250°C and a pressure of 100 Pa, and after viscosity increasing for 12 hours, it is taken out and crushed to obtain a high-temperature resistant polyamide resin.

[0107] (5) After drying, the copolyamide resin and antioxidant 1098 (added at 1 wt%) were added to a twin-screw extruder. The spinning temperature was set at 330 °C. The melt stream extruded from the spinneret was cooled by side blowing cold air at 0.6 m / s in the spinning tunnel to obtain the nascent fiber.

[0108] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 40 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0109] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 210°C, the drawing ratio was 3.6 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.5 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2400 m / min.

[0110] Comparative Example 3

[0111] (1) The mass and proportion of each raw material are as follows: accurately weigh 10 mol of decanediamine, 8 mol of terephthalic acid and 2 mol of adipic acid, and 0.1 mol of benzoic acid, the amount of catalyst sodium hypophosphite and antioxidant SEED is 0.1 wt% of the total mass of diamine and diacid, and add 50 wt% of deionized water.

[0112] (2) All the above raw materials were added to the polymerization kettle, and the temperature was increased at a heating rate of 5°C / min under a nitrogen atmosphere. Stirring was started at 90°C, the stirring rate was controlled at 50 rpm, and the stirring time was 1 hour to promote the salt formation of the diacid and diamine monomers in the solution.

[0113] (3) The temperature was further increased to 210°C at a heating rate of 5°C / min, and the pressure was increased to 2.2~2.5MPa. Appropriate exhaust was performed to maintain the pressure stable. After maintaining the temperature and pressure for 2h, the temperature was again increased to 255°C, and the pressure was adjusted to 2.5~3MPa. After maintaining the temperature and pressure for 1h, when the water output reached 12wt% of the total feed amount, the discharge valve was opened to flash-evaporate the material, which was then crushed and dried to obtain a semi-aromatic copolyamide prepolymer.

[0114] (4) The semi-aromatic copolyamide prepolymer is placed in a high-temperature drum oven, maintained at a temperature of 250°C and a pressure of 100 Pa, and taken out after viscosity increasing for 10 hours, and crushed to obtain a high-temperature resistant polyamide resin.

[0115] (5) After drying, the copolyamide resin was added to a twin-screw extruder together with antioxidant 1098 (added at 1 wt%). The spinning temperature was set at 330 °C. The melt stream extruded from the spinneret was cooled by a 0.8 m / s side-blown air flow in the spinning tunnel to obtain nascent fibers.

[0116] (6) The nascent fiber is drawn by the spinneret through the first hot winding roller. The spinneret drawing ratio is 40 times. The temperature of the first collecting roller is 100 °C and the rotation speed is 500 m / min to obtain undrawn fiber.

[0117] (7) The undrawn yarn was subjected to primary and secondary drawing. The primary drawing temperature was 210°C, the drawing ratio was 3.5 times, the secondary drawing temperature was 220°C, the drawing ratio was 1.5 times, the first heat setting temperature was 190°C, the relaxation rate was 5%, the second heat setting temperature was 200°C, the relaxation rate was 4%, and the final winding speed was 2400 m / min.

[0118] Performance Testing The polyamide fibers obtained in the Examples and Comparative Examples were tested for breaking strength, elongation at break, strength retention after 6 hours at 200°C, melting point, and polyamide resin melt flow index (g / 10 min) at 320°C. The results are listed in Table 1. The breaking strength and elongation of the fibers were characterized according to GB / T 14344-2008, "Test Method for Tensile Properties of Chemical Fibers - Filaments." The test parameters were set as follows: a preload of 0.05±0.005 cN / dtex, a clamp distance of 500 mm, and a tensile rate of 500 mm / min. The polyamide resin melt flow index was tested according to GB / T 3682.1-2018. The test method involved compacting dried resin slices into the tester tube. A standard die with a diameter of 2.095 mm and a length of 8 mm was used. The mass of polyamide resin flowing out at 320°C was measured every 10 minutes under a load of 2.16 kg.

[0119] Table 1 Comparison of performance indicators of the embodiment and the comparative example

[0120] It can be seen that the present invention can achieve a synergistic improvement in the mechanical strength and high temperature resistance of polyamide fibers while retaining melt spinnability.

[0121] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing high-strength and high-temperature resistant polyamide fiber, characterized in that: The following steps are involved: (1) Providing a polyamide prepolymer; the polyamide prepolymer includes a random copolymerized polyamide prepolymer and / or a block copolymerized polyamide prepolymer; the polyamide prepolymer has a semi-aromatic polyamide structure, and the random copolymerized polyamide prepolymer contains a meta-aromatic structural unit and / or a phenylene ether amine structural unit in its structure; (2) performing vacuum solid phase viscosity enhancement on the polyamide prepolymer to obtain a high temperature resistant polyamide resin; (3) mixing the high temperature resistant polyamide resin with an antioxidant, performing twin-screw melt mixing, spinneret extrusion and porous aerosol spray gradient cooling to obtain spun fibers; The porous aerosol spray gradient cooling comprises: At a distance of 0 to 10 cm from the spinneret, nitrogen cooling at a temperature of -30 to -20 °C was used; At a distance of 10-50 cm from the spinneret, atomized silicone oil with a temperature of 100-120°C is used for cooling; At a distance of 50-100 cm from the spinneret, hot air with a temperature of 80°C is used for cooling; (4) The spun fibers are subjected to spinneret drawing, temperature-stress coordinated multi-stage drawing, and multi-stage heat setting to obtain high-strength and high-temperature resistant polyamide fibers.

2. The preparation method according to claim 1, characterized in that The molecular weight of the polyamide prepolymer is 3000-8000 g / mol; The random copolymerized polyamide prepolymer has a structure shown in Formula 1: Formula 1; In formula 1, n = 0, 2, 5 or 6; x:y = 3~4:1 The block copolymer polyamide prepolymer has a structure shown in Formula 2: Formula 2; In formula 2, n = 0, 2, 5 or 6; w:v = 6~8:1; In Formula 1 and Formula 2, A and B are independently one or more of the following structures: A= 、 or ; B= 、 or .

3. The preparation method according to claim 1 or 2, characterized in that The preparation method of the random copolymerized polyamide prepolymer comprises the following steps: Mixing a diamine monomer, a diacid monomer, a catalyst, an antioxidant, a capping agent and water, and sequentially performing a salt-forming reaction and a polymerization reaction to obtain a random copolymer polyamide prepolymer; The polymerization reaction temperature is 250-270° C. and the pressure is 2-3 MPa.

4. The preparation method according to claim 1 or 2, characterized in that The preparation method of the block copolymer polyamide prepolymer comprises the following steps: Mixing the blocked first prepolymer and the blocked second prepolymer and performing melt polycondensation to obtain a block copolymer polyamide prepolymer; The end-capping groups of the first prepolymer and the second prepolymer are amino groups or carboxyl groups; and the preparation method of the first prepolymer or the second prepolymer comprises the following steps: The diamine monomer, the diacid monomer, the antioxidant and water are mixed and subjected to polycondensation reaction to obtain a prepolymer.

5. The preparation method according to claim 1, characterized in that The vacuum solid phase viscosity enhancement process is carried out at a temperature of 220-250°C, a pressure of 100-150 Pa, and a time of 6-12 hours. The high-temperature resistant polyamide resin has a melting point of 280-300° C., a molecular weight of 20,000-30,000 g / mol, and a melt flow index of 40-50 g / 10 min at 320° C.

6. The preparation method according to claim 1 or 5, characterized in that The mass of the antioxidant is 1-5% of the mass of the high-temperature resistant polyamide resin; The temperature of the twin-screw melt mixing is 310-330°C.

7. The preparation method according to claim 1, characterized in that The drafting ratio of the spinneret is 30 to 50 times; The temperature-stress coordinated multi-stage drawing includes a primary drawing and a secondary drawing; The temperature of the first-stage drawing is 190-220°C, and the drawing ratio is 3.5-3.8 times; The temperature of the secondary drawing is 180-220° C., and the drawing ratio is 1.2-1.5 times.

8. The preparation method according to claim 1 or 7, characterized in that The multi-stage heat setting includes a first heat setting and a second heat setting; The temperature of the first heat setting is 190-200°C; The temperature of the second heat setting is 180-230°C.

9. The high-strength and high-temperature-resistant polyamide fiber prepared by the preparation method according to any one of claims 1 to 8.

10. The high-strength and high-temperature resistant polyamide fiber according to claim 9, characterized in that: The polyamide fiber has a breaking strength of 10-12 cN / dtex, an elongation at break of 20-25%, and a strength retention rate of >95% after heat treatment at 200° C. for 6 hours.

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