High-quality copolymerized flame-retardant nylon 66 fiber and preparation method thereof
By copolymerizing reactive phosphorus-based flame retardants with nylon salts and using chain extenders and compound stabilizers, the problems of nylon 66 fiber's flammability and melt dripping were solved, achieving a balance of high flame retardancy, mechanical properties, and thermal stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG SCI-TECH UNIV
- Filing Date
- 2026-03-23
- Publication Date
- 2026-05-12
AI Technical Summary
Nylon 66 fiber is flammable and melts and drips when burning. Traditional flame-retardant modification methods result in significant loss of mechanical properties and make it difficult to balance thermal stability and spinnability.
High-quality copolymer flame-retardant nylon 66 fibers were prepared by copolymerizing reactive phosphorus-based flame retardants with nylon salts, combined with chain extenders and compound stabilizers. Flame-retardant units were grafted through chemical bonds and the molecular chain structure was optimized.
It achieves high flame retardancy (UL 94 V-0 rating, no melt dripping), high strength (breaking strength ≥4.5 cN/dtex) and good thermal stability, significantly improving the overall performance of the fiber.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of nylon fiber preparation, specifically relating to a high-quality copolymer flame-retardant nylon 66 fiber and its preparation method. Background Technology
[0002] Nylon 66 (polyhexamethylene adipamide) is an important engineering plastic and synthetic fiber raw material. Due to its high strength, high abrasion resistance, chemical corrosion resistance, and good processing performance, it is widely used in the automotive, electronics, textile, and special protection industries. PA66 fiber possesses excellent mechanical properties, including high strength, abrasion resistance, impact resistance, and outstanding fatigue resistance. It also exhibits good thermal stability, resistance to organic solvents and weak acid and alkali corrosion, good spinnability, easy dyeing, and the ability to blend with natural fibers. Furthermore, it has moderate moisture absorption, dimensional stability, and is not easily deformed, making it suitable for various applications such as high-strength textiles, industrial consumables, and clothing fabrics. However, Nylon 66 has a limiting oxygen index (LOI) of only about 22-24%, classifying it as a flammable material. During combustion, it produces molten drips that can easily ignite other substances and cause the fire to spread. This severely limits its application in high-end applications requiring flame retardancy (such as aerospace interiors, fire-fighting suits, and special industrial fabrics).
[0003] Introducing flame retardants is an effective way to improve the flame retardancy of nylon materials. Currently, there are two main methods for preparing flame-retardant nylon materials: one is blending, where flame retardants are added to the nylon matrix; the other is copolymerization, where flame retardants with flame-retardant groups are combined with nylon 66 salt through a series of reactions to prepare inherently flame-retardant nylon. In preparing highly oriented, high-strength fibers, the polymer melt needs to have suitable viscoelasticity. To obtain high-performance nylon, researchers have been studying and developing technologies for high molecular weight or high-viscosity nylon. One approach is to increase the molecular weight through polycondensation; another is to increase viscosity through grafting, crosslinking, chain extension, and other modification methods. Nylon molecular chains contain amino and carboxyl groups at their ends, which exhibit certain reactivity under specific conditions, providing a basis for chemical chain extension. Adding epoxides, bisoxazoline compounds, isocyanates, etc. to nylon creates bifunctional compounds that contain functional groups that readily react with carboxyl and amino groups. These compounds can directly react with low molecular weight nylon oligomers, forming a "bridge" between the two polymer chains, significantly increasing the molecular weight, improving the viscosity of the system, and reducing the end-group content.
[0004] Chinese patent CN105131280A discloses a halogen-free flame-retardant nylon 66 resin and its preparation method. The method uses an organophosphorus ammonium salt prepared from a phosphonic diacid and a commonly used diamine as the flame-retardant component, which is then copolymerized with nylon salt. To overcome the problem of flame retardant decomposition due to excessively high temperatures during nylon 66 polymerization and processing, this invention adds 0-0.2 parts by weight of antioxidant, resulting in a high-viscosity, non-dripping, and high-mechanical-performance halogen-free flame-retardant copolymerized nylon 66 resin. Summary of the Invention
[0005] This invention aims to overcome the shortcomings of existing technologies and solve the defects of nylon 66 fiber, such as flammability and melting and dripping during combustion. At the same time, it improves the problems of traditional flame retardant modification methods (large loss of mechanical properties in blending, easy high-temperature decomposition of flame retardants in traditional copolymerization, and difficulty in balancing fiber thermal stability and spinnability). It uses a reactive phosphorus-based flame retardant diacid and a commonly used diamine to prepare an organophosphorus ammonium salt as a flame retardant component, which is then copolymerized with nylon salt. This provides a method for preparing fiber products with excellent flame retardant properties, high mechanical strength, good thermal stability, and excellent spinning properties.
[0006] In a first aspect, the present invention provides a high-quality copolymer flame-retardant nylon 66 fiber, which is prepared by copolymerization reaction from raw materials comprising the following components in parts by weight: 92-100 parts of Nylon 66 salt; 2-7 parts of flame retardant salt, wherein the flame retardant salt is prepared by reacting a reactive phosphorus-based flame retardant with an aliphatic diamine to form a salt; Chain extender 0.2~2 parts; Compound stabilizer 0.1~1 part; and Dispersant 0.2~1 part.
[0007] Furthermore, the reactive phosphorus-based flame retardant is [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphorylhexane-6-yl)methyl]succinic acid (DDP) or 3-hydroxyphenylphosphonopropionic acid (CEPPA); the aliphatic diamine has the general structural formula H2N-(CH2). x -NH2, where x is an integer from 4 to 10.
[0008] Furthermore, the chain extender is selected from at least one of styrene-glycidyl methacrylate copolymer epoxy chain extenders and bisoxazoline chain extenders.
[0009] Furthermore, the styrene-glycidyl methacrylate copolymer epoxy chain extender is from the JoncrylADR series; the bisoxazoline chain extender is selected from at least one of 2,2'-bis(2-oxazoline) (BOZ), 1,3-bis(2-oxazoline)benzene (PBO), and 1,4-bis(2-oxazoline)benzene (PBOX).
[0010] Furthermore, the compound stabilizer is composed of hindered phenolic antioxidants and phosphite heat stabilizers; the dispersant is an aliphatic amide or wax dispersant.
[0011] Furthermore, the hindered phenolic antioxidant is antioxidant 1010 or 1076, the phosphite heat stabilizer is antioxidant 168 or 626, and the dispersant is ethylene bis-stearamide (EBS) or oxidized polyethylene wax (OPE).
[0012] Furthermore, the fiber has a breaking strength ≥4.5 cN / dtex, a breaking elongation of 25%~30%, and a flame retardant rating of UL 94 V-0.
[0013] In a second aspect, the present invention also provides a method for preparing high-quality copolymer flame-retardant nylon 66 fibers as described in any one of the first aspects, comprising the following steps: (1) A reactive phosphorus-based flame retardant is reacted with an aliphatic diamine in a polar solvent to form a salt, thereby preparing a flame retardant salt; (2) According to the mass fractions described in the first aspect, add nylon 66 salt, flame retardant salt obtained in step (1), chain extender, compound stabilizer, dispersant and deionized water to the polymerization reactor to carry out copolymerization reaction to obtain copolymer flame retardant nylon 66 with flame retardant structure; (3) The copolymer flame-retardant nylon 66 obtained in step (2) is subjected to solid-phase thickening treatment; (4) The thickened copolymer flame-retardant nylon 66 chips were melt-spun to obtain copolymer flame-retardant nylon 66 fibers.
[0014] Furthermore, in the above preparation method, the specific process conditions for the copolymerization reaction in step (2) are as follows: after replacing the air in the reactor with nitrogen, the temperature is raised to 210~220℃, the pressure is maintained at 1.8~2.0 MPa, and polycondensation is carried out for 2~3 h; then the temperature is raised to 245~255℃, and the pressure is reduced to atmospheric pressure within 0.5~1 h; finally, the temperature is raised to 270~280℃, the vacuum is drawn to a pressure of 50~200 Pa, and the temperature and pressure are maintained for 1~3 h.
[0015] Furthermore, in the above preparation method, the solid phase thickening temperature in step (3) is 160~220℃ and the time is 4~24 hours; the melt spinning temperature in step (4) is 280~295℃, the winding speed is 2500~3500 m / min, and the draw ratio is 3.0~4.5.
[0016] Compared with existing technologies, the present invention has the following advantages and beneficial effects: (1) Excellent flame retardant performance: This invention uses a reactive phosphorus-based flame retardant to graft flame retardant units onto the nylon 66 molecular chain through chemical bonds, achieving intrinsic flame retardant modification and effectively avoiding the problems of flame retardant migration and precipitation in traditional blending modification. The resulting fiber flame retardant rating can reach UL 94 V-0, with no melting and dripping during combustion, and the limiting oxygen index (LOI) is significantly improved to over 27%, which can meet the stringent requirements for flame retardant materials in high-end fields such as aerospace and fire protection.
[0017] (2) Excellent mechanical properties: By introducing a chain extender into the copolymer system, the chain extender reacts with the amino and carboxyl groups at the ends of the nylon molecular chains to form a "bridging" structure, which effectively improves the molecular weight and melt viscoelasticity of the polymer, optimizes the entanglement state of the molecular chains, and significantly compensates for the loss of mechanical properties caused by the introduction of flame retardant components. The resulting fiber has a breaking strength ≥4.5 cN / dtex and a breaking elongation controlled within a suitable range of 25%~30%, possessing both high strength and good toughness.
[0018] (3) Good thermal stability and spinnability: The use of hindered phenolic antioxidants and phosphite heat stabilizers synergistically inhibits thermal oxidative degradation reactions during high-temperature polymerization and melt spinning, ensuring the thermal stability of the polymer; combined with the uniform dispersion effect of the dispersant, the melt flowability is uniform and controllable, significantly improving the spinnability of the fiber and the stability of product quality. Detailed Implementation
[0019] The present invention will be further described below with reference to specific embodiments, but these embodiments are not intended to limit the scope of protection of the present invention. Equivalent substitutions or improvements made by those skilled in the art based on the present invention all fall within the scope of protection of the present invention.
[0020] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the reagents and materials used can be obtained commercially or prepared according to existing technical methods.
[0021] Example 1 1. Salt formation reaction: Add 2 parts of flame retardant DDP and hexamethylenediamine (x=6) to ethanol in a molar ratio of 1:1, stir at 60°C for 2 hours, cool to crystallize, filter and dry to obtain flame retardant DDP salt; 2. Polymerization reaction: Flame retardant DDP salt, 96.7 parts of nylon 66 salt, 0.5 parts of chain extender Joncryl ADR 4368, 0.3 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 0.3 parts of dispersant EBS, and 70 parts of deionized water were added to the polymerization reactor, and the reactor was purged with nitrogen three times; the temperature was raised to 215℃ and the pressure was 1.9MPa for condensation for 2.5h; the temperature was raised to 250℃ and the pressure was reduced to normal for 1h; the temperature was raised to 275℃, the vacuum was drawn to 100Pa, and the temperature and pressure were maintained for 2h to obtain copolymerized nylon 66; 3. Solid-phase thickening: Thickening at 180℃ for 12 hours; 4. Melt spinning: Temperature 285℃, winding speed 3000m / min, draw ratio 4.0, to obtain the target fiber.
[0022] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0023] Example 2 1. Salt formation reaction: Add 2 parts of flame retardant CEPPA and hexamethylenediamine (x=6) to ethanol in a molar ratio of 1:1, stir at 60°C for 2 hours, cool to crystallize, filter and dry to obtain flame retardant CEPPA salt; 2. Polymerization reaction: CEPPA flame retardant salt, 96.7 parts nylon 66 salt, 0.5 parts chain extender BOZ, 0.3 parts antioxidant 1076, 0.2 parts antioxidant 626, 0.3 parts dispersant OPE, and 70 parts deionized water were added to the polymerization reactor and purged with nitrogen three times; the temperature was raised to 220℃ and the pressure was 2.0MPa for 2 hours of polycondensation; the temperature was raised to 255℃ and the pressure was reduced to atmospheric pressure after 0.8 hours; the temperature was raised to 270℃, the vacuum was drawn to 80Pa, and the temperature and pressure were maintained for 1.5 hours to obtain copolymerized nylon 66; 3. Solid-phase thickening: Thickening at 200℃ for 8 hours; 4. Melt spinning: Temperature 287℃, winding speed 2800m / min, draw ratio 4.0, to obtain the target fiber.
[0024] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0025] Example 3 1. Salt formation reaction: 4 parts of flame retardant DDP and hexamethylenediamine (x=6) were added to ethanol at a molar ratio of 1:1, stirred at 60°C for 2 hours, cooled to crystallize, filtered and dried to obtain flame retardant DDP salt; 2. Polymerization reaction: Flame retardant DDP salt, 94.6 parts of nylon 66 salt, 0.5 parts of chain extender PBO, 0.3 parts of antioxidant 1010, 0.2 parts of antioxidant 626, 0.4 parts of dispersant EBS, and 65 parts of deionized water were added to the polymerization reactor and purged with nitrogen three times; the temperature was raised to 210℃ and the pressure was 1.8MPa for condensation for 2 hours; the temperature was raised to 245℃ and reduced to atmospheric pressure for 0.5 hours; the temperature was raised to 272℃, the vacuum was drawn to 80Pa, and the temperature and pressure were maintained for 2.5 hours to obtain copolymerized nylon 66; 3. Solid-phase thickening: Thickening at 190℃ for 16 hours; 4. Melt spinning: Temperature 288℃, winding speed 3200m / min, draw ratio 3.9.
[0026] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0027] Example 4 1. Salt formation reaction: 4 parts of flame retardant CEPPA and hexamethylenediamine (x=6) were added to ethanol at a molar ratio of 1:1, stirred at 60°C for 2 hours, cooled to crystallize, filtered and dried to obtain flame retardant DDP salt; 2. Polymerization reaction: CEPPA flame retardant salt, 94.6 parts nylon 66 salt, 0.5 parts chain extender PBOX, 0.3 parts antioxidant 1076, 0.2 parts antioxidant 168, 0.4 parts dispersant OPE, and 65 parts deionized water were added to the polymerization reactor and purged with nitrogen three times; the temperature was raised to 215℃ and the pressure was 1.85MPa for 2 hours of polycondensation; the temperature was raised to 248℃ and the pressure was reduced to atmospheric pressure after 0.8 hours; the temperature was raised to 270℃, the vacuum was drawn to 80Pa, and the temperature and pressure were maintained for 1.5 hours to obtain copolymerized nylon 66; 3. Solid-phase thickening: Thickening at 170℃ for 20 hours; 4. Melt spinning: Temperature 282℃, winding speed 3400m / min, draw ratio 3.9.
[0028] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0029] Example 5 1. Salt formation reaction: 6 parts of flame retardant DDP and hexamethylenediamine (x=6) were added to ethanol at a molar ratio of 1:1, stirred at 60°C for 2 hours, cooled to crystallize, filtered and dried to obtain flame retardant DDP salt; 2. Polymerization reaction: Flame retardant DDP salt, 92.2 parts of nylon 66 salt, 0.3 parts of chain extender Joncryl ADR 4368, 0.3 parts of chain extender BOZ, 0.4 parts of antioxidant 1076, 0.3 parts of antioxidant 168, 0.5 parts of dispersant EBS, and 60 parts of deionized water were added to the polymerization reactor, and the reactor was purged with nitrogen three times. The temperature was raised to 215℃ and the pressure was 2.0MPa for condensation for 2 hours. The temperature was raised to 255℃ and the pressure was reduced to normal for 1 hour. The temperature was raised to 270℃, the vacuum was drawn to 80Pa, and the temperature and pressure were maintained for 1.8 hours to obtain copolymerized nylon 66. 3. Solid-phase viscosity enhancement: Viscosity enhancement at 210℃ for 6 hours; 4. Melt spinning: Temperature 292℃, winding speed 2600m / min, draw ratio 4.0.
[0030] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0031] Example 6 1. Salt formation reaction: 6 parts of flame retardant CEPPA and hexamethylenediamine (x=6) were added to ethanol at a molar ratio of 1:1, stirred at 60°C for 2 hours, cooled to crystallize, filtered and dried to obtain flame retardant CEPPA salt; 2. Polymerization reaction: CEPPA flame retardant salt, 92.2 parts nylon 66 salt, 0.3 parts chain extender PBO, 0.3 parts PBOX, 0.4 parts antioxidant 1076, 0.3 parts antioxidant 626, 0.5 parts dispersant OPE, and 60 parts deionized water were added to the polymerization reactor and purged with nitrogen three times; the temperature was raised to 220℃ and the pressure was 2.0MPa for 2 hours of polycondensation; the temperature was raised to 251℃ and the pressure was reduced to normal for 1 hour; the temperature was raised to 270℃, the vacuum was drawn to 80Pa, and the temperature and pressure were maintained for 1.5 hours to obtain copolymerized nylon 66; 3. Solid-phase thickening: Thickening at 200℃ for 10 hours; 4. Melt spinning: Temperature 286℃, winding speed 3100m / min, draw ratio 4.0.
[0032] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0033] Comparative Example 1 1. Polymerization reaction: 98.7 parts of nylon 66 salt, 0.5 parts of chain extender Joncryl ADR 4368, 0.3 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 0.3 parts of dispersant EBS, and 70 parts of deionized water were added to the polymerization reactor and purged with nitrogen three times; the temperature was raised to 215℃ and the pressure was 1.9MPa for condensation polymerization for 2.5h; the temperature was raised to 250℃ and reduced to atmospheric pressure for 1h; the temperature was raised to 275℃, the vacuum was drawn to 100Pa, and the temperature and pressure were maintained for 2h to obtain copolymerized nylon 66; 2. Solid-phase thickening: Thickening at 180℃ for 12 hours; 3. Melt spinning: Temperature 280℃, winding speed 3000m / min, draw ratio 4.0, to obtain the target fiber.
[0034] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0035] No flame retardant salts were added to the raw material components of this comparative example. The other additives (chain extender, stabilizer, dispersant) and preparation process (polymerization, solid phase thickening, melt spinning) were consistent with those of Example 1, in order to verify that the introduction of flame retardant units can make the target fiber achieve a better flame retardant effect.
[0036] Comparative Example 2 1. Salt formation reaction: Add 2 parts of flame retardant DDP and hexamethylenediamine (x=6) to ethanol in a molar ratio of 1:1, stir at 60°C for 2 hours, cool to crystallize, filter and dry to obtain flame retardant DDP salt; 2. Polymerization reaction: Flame retardant DDP salt, 97.2 parts of nylon 66 salt, 0.3 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 0.3 parts of dispersant EBS, and 70 parts of deionized water were added to the polymerization reactor, and the reactor was purged with nitrogen three times; the temperature was raised to 215℃ and the pressure was 1.9MPa for condensation for 2.5h; the temperature was raised to 250℃ and the pressure was reduced to normal for 1h; the temperature was raised to 275℃, the vacuum was drawn to 100Pa, and the temperature and pressure were maintained for 2h to obtain copolymerized nylon 66; 3. Solid-phase thickening: Thickening at 180℃ for 12 hours; 4. Melt spinning: Temperature 280℃, winding speed 3000m / min, draw ratio 4.0, to obtain the target fiber.
[0037] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0038] No chain extender was added to the raw material components of this comparative example. The other auxiliaries (flame retardant salt, stabilizer, dispersant) and preparation process (polymerization, solid phase thickening, melt spinning) were consistent with those of Example 1, in order to verify that the addition of chain extender can enable the target fiber to obtain better mechanical properties and spinnability.
[0039] Comparative Example 3 1. Salt formation reaction: Add 2 parts of flame retardant DDP and hexamethylenediamine (x=6) to ethanol in a molar ratio of 1:1, stir at 60°C for 2 hours, cool to crystallize, filter and dry to obtain flame retardant DDP salt; 2. Polymerization reaction: Flame retardant DDP salt, 97.2 parts of nylon 66 salt, 0.5 parts of chain extender Joncryl ADR 4368, 0.3 parts of dispersant EBS, and 70 parts of deionized water were added to the polymerization reactor, and the reactor was purged with nitrogen three times; the temperature was raised to 215℃ and the pressure was 1.9MPa for 2.5h of polycondensation; the temperature was raised to 250℃ and the pressure was reduced to atmospheric pressure after 1h; the temperature was raised to 275℃, the vacuum was drawn to 100Pa, and the temperature and pressure were maintained for 2h to obtain copolymerized nylon 66; 3. Solid-phase thickening: Thickening at 180℃ for 12 hours; 4. Melt spinning: Temperature 280℃, winding speed 3000m / min, draw ratio 4.0, to obtain the target fiber.
[0040] The fibers were tested according to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 5454-1997 "Test Method for Burning Performance of Textiles by Oxygen Index Method" and GB / T 5455-2014 "Determination of Vertical Destruction Length, Afterflame and Afterflame Time of Burning Performance of Textiles".
[0041] No compound stabilizers (hindered phenolic antioxidants and phosphite heat stabilizers) were added to the raw material components of this comparative example. The remaining additives (flame retardant salts, chain extenders, dispersants) and preparation processes (polymerization, solid-phase thickening, melt spinning) were consistent with those of Example 1. The aim was to verify that the introduction of compound stabilizers could effectively inhibit the thermal degradation of the copolymer system and ensure the thermal stability of the fiber.
[0042] Test case The fiber samples prepared in Examples 1-6 and Comparative Examples 1-3 of this invention were subjected to performance tests, and the specific test methods are as follows: (1) Breaking strength and elongation at break: determined in accordance with GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments"; (2) Flame retardancy rating: The flame retardancy rating was determined according to UL 94 standard, and the burning behavior and melting dripping of the sample were recorded. (3) Limiting oxygen index (LOI): Determined according to GB / T 5454-1997 "Test for flammability of textiles - oxygen index method".
[0043] The test results are shown in Table 1.
[0044] Table 1. Fiber performance test results for each embodiment and comparative example.
[0045] As can be seen from the test results in Table 1: The fibers prepared in Examples 1-6 of this invention all have a breaking strength of 4.5 cN / dtex or higher, a breaking elongation controlled within a suitable range of 25% to 30%, a flame retardancy rating of UL 94 V-0 with no melt dripping, and a limiting oxygen index of 27% or higher, exhibiting excellent comprehensive performance.
[0046] In comparison, Comparative Example 1 (without added flame retardant salt) had good mechanical properties, but its flame retardancy rating was only V-2 and its LOI value was only 22%, classifying it as a flammable material. Comparative Example 2 (without added chain extender) met the flame retardancy standard, but its breaking strength decreased significantly to 3.8 cN / dtex and its breaking elongation also decreased to 19%, resulting in severely compromised mechanical properties. Comparative Example 3 (without added compound stabilizer) had a breaking strength and breaking elongation of 4.4 cN / dtex and 20%, respectively, which were better than Comparative Example 2 but still lower than the levels of the examples, indicating that compound stabilizers play an important role in ensuring the mechanical properties of fibers.
[0047] In summary, the fiber prepared by the present invention through copolymerization combined with a specific chain extender and a compound stabilizer system has excellent flame retardant properties, mechanical properties and spinnability, which is significantly better than the comparative scheme lacking key auxiliaries.
[0048] The above embodiments and test examples are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the present invention without departing from the concept of the present invention should fall within the scope of protection of the present invention.
Claims
1. A high-quality copolymer flame-retardant nylon 66 fiber, characterized in that, It is prepared by copolymerization of raw materials comprising the following components in parts by weight: 92-100 parts of Nylon 66 salt; 2-7 parts of flame retardant salt; Chain extender 0.2~2 parts; Add 0.1 to 1 part of compound stabilizer; Dispersant 0.2~1 part; The flame retardant salt is prepared by reacting a reactive phosphorus-based flame retardant with an aliphatic diamine to form a salt.
2. The high-quality copolymer flame-retardant nylon 66 fiber according to claim 1, characterized in that, The reactive phosphorus-based flame retardant is [(6-oxo-6H-dibenzo[C,E][1,2]oxophosphorylhexane-6-yl)methyl]succinic acid (DDP) or 3-hydroxyphenylphosphonopropionic acid (CEPPA); the aliphatic diamine has the general structural formula H2N-(CH2). x -NH2, where x is an integer from 4 to 10.
3. The high-quality copolymer flame-retardant nylon 66 fiber according to claim 1, characterized in that, The chain extender is selected from at least one of styrene-glycidyl methacrylate copolymer epoxy chain extenders and bisoxazoline chain extenders.
4. The high-quality copolymer flame-retardant nylon 66 fiber according to claim 3, characterized in that, The styrene-glycidyl methacrylate copolymer epoxy chain extender is the Joncryl ADR series; the bisoxazoline chain extender is selected from at least one of 2,2'-bis(2-oxazoline) (BOZ), 1,3-bis(2-oxazoline)benzene (PBO), and 1,4-bis(2-oxazoline)benzene (PBOX).
5. The high-quality copolymer flame-retardant nylon 66 fiber according to claim 1, characterized in that, The compound stabilizer is composed of hindered phenolic antioxidants and phosphite heat stabilizers; the dispersant is an aliphatic amide or wax dispersant.
6. The high-quality copolymer flame-retardant nylon 66 fiber according to claim 5, characterized in that, The hindered phenolic antioxidant is antioxidant 1010 or 1076, and the phosphite heat stabilizer is antioxidant 168 or 626; the dispersant is ethylene bis-stearamide (EBS) or oxidized polyethylene wax (OPE).
7. The high-quality copolymer flame-retardant nylon 66 fiber according to any one of claims 1 to 6, characterized in that, The fiber has a breaking strength ≥4.5 cN / dtex, a breaking elongation of 25%~30%, and a flame retardant rating of UL 94 V-0.
8. A method for preparing high-quality copolymer flame-retardant nylon 66 fiber as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (1) A reactive phosphorus-based flame retardant is reacted with an aliphatic diamine in a polar solvent to form a salt, thereby preparing a flame retardant salt. (2) According to the mass fractions described in claim 1, add nylon 66 salt, flame retardant salt obtained in step (1), chain extender, compound stabilizer, dispersant and deionized water to a polymerization reactor to carry out a copolymerization reaction to obtain copolymer flame retardant nylon 66 with flame retardant structure. (3) The copolymer flame-retardant nylon 66 obtained in step (2) is subjected to solid-phase thickening treatment; (4) The thickened copolymer flame-retardant nylon 66 chips were melt-spun to obtain copolymer flame-retardant nylon 66 fibers.
9. The preparation method according to claim 8, characterized in that, The specific process conditions for the copolymerization reaction described in step (2) are as follows: after replacing the air in the reactor with nitrogen, the temperature is raised to 210~220℃, the pressure is maintained at 1.8~2.0 MPa, and polycondensation is carried out for 2~3 h; then the temperature is raised to 245~255℃, and the pressure is reduced to atmospheric pressure within 0.5~1 h; finally, the temperature is raised to 270~280℃, the vacuum is drawn to a pressure of 50~200 Pa, and the temperature and pressure are maintained for 1~3 h.
10. The preparation method according to claim 8, characterized in that, The solid phase thickening temperature in step (3) is 160~220℃ and the time is 4~24 hours; the melt spinning temperature in step (4) is 280~295℃, the winding speed is 2500~3500 m / min, and the draw ratio is 3.0~4.5.