Nylon 6 master batch with flame-retardant function, chinlon 6 fiber and preparation method of nylon 6 master batch and chinlon 6 fiber

Abstract

The invention discloses a nylon 6 master batch with a flame-retardant function, a nylon 6 fiber and a preparation method of the nylon 6 fiber, and belongs to the technical field of halogen-free flame-retardant master batches. The nylon 6 master batch comprises a nylon 6 matrix, a flame retardant, a rare earth synergist and a dispersing agent polyether ester high-molecular polymer, a two-step method is adopted, the flame retardant, the synergist and the dispersing agent are coated in low-melting-point polyamide wax through a pre-dispersion system to form pre-dispersion particles, then the pre-dispersion particles and the nylon 6 matrix are subjected to melt blending granulation, and the nylon 6 master batch is obtained. The technical problems that the additive is easy to agglomerate, low in stacking density and difficult to accurately feed are effectively solved; meanwhile, the nylon-6 fiber is prepared by mixing the nylon-6 master batches according to a proportion and adopting a melt spinning process, and the nylon-6 fiber has excellent flame retardant property, not only is high limit oxygen index and remarkably reduced molten drop phenomenon, but also keeps good breaking strength and elongation, has equivalent mechanical properties to conventional fibers, and is suitable for industrial production. And the method is suitable for industrial continuous production.

Description

Technical Field

[0001] This invention belongs to the field of halogen-free flame retardant masterbatch technology, specifically relating to a nylon 6 masterbatch with flame retardant function, nylon 6 fiber and its preparation method. Background Technology

[0002] Nylon, scientifically known as polyamide, is the world's first industrially produced synthetic fiber. Due to the presence of strongly polar amide bonds in its molecular chain, it possesses a series of excellent physicochemical properties. Among them, Nylon 6 (nylon 6) occupies an irreplaceable and important position in textiles, clothing, and industrial textiles due to its high tensile strength, excellent abrasion resistance, good alkali resistance and resilience, as well as mature polymerization and spinning processes. Its applications have expanded from everyday clothing, sportswear, carpets, and curtains to the automotive industry and even high-end fields such as military and aerospace. However, Nylon 6 has a low limiting oxygen index, only around 21%-22%, classifying it as a flammable material, which greatly limits its application in many scenarios with strict fire safety requirements.

[0003] The combustion process of nylon 6 fiber is a violent thermo-oxidative degradation process. When exposed to open flames or high temperatures, the fiber rapidly melts and decomposes, producing flammable gases and accompanied by severe dripping. These high-temperature drips not only carry the flame and ignite other combustibles, accelerating the spread of the fire, but also cause serious secondary injuries to personnel. Therefore, flame-retardant modification of nylon 6 fiber to improve its flame resistance and suppress dripping is an important direction for achieving safe applications and expanding market boundaries. Currently, research on flame-retardant modification of nylon 6 fiber can be mainly divided into two categories in terms of technical approaches: surface post-treatment methods and blending modification methods.

[0004] Surface treatment methods primarily utilize techniques such as padding, coating, and graft polymerization to construct a flame-retardant protective layer on the surface of fibers or fabrics. While this method has minimal impact on the mechanical properties of the fiber itself, it generally suffers from poor durability. After repeated washing or friction, the flame-retardant effect significantly diminishes, failing to meet the requirements of textiles requiring long-term use or frequent washing. Furthermore, surface treatments can alter the fabric's feel, style, and breathability, affecting its wearing comfort. In contrast, blending modification methods, by uniformly adding flame retardants to the polymer melt before spinning, produce inherently flame-retardant fibers. This method imparts long-lasting and stable flame-retardant properties, unaffected by subsequent washing and processing, and represents the mainstream approach and development direction for achieving permanent flame retardancy in nylon 6 fibers.

[0005] However, the blending modification method still has drawbacks in industrial practice, especially in melt spinning processes where the purity, rheological properties, and thermal stability of raw materials are extremely important. Firstly, the introduction of flame retardants, particularly large amounts of inorganic or organic-inorganic hybrid flame retardants, severely disrupts the rheological homogeneity of the nylon 6 melt, leading to decreased melt strength and altered elasticity. This can easily cause filament breakage, fuzzing, or even prevent continuous spinning during the spinning process. Simultaneously, flame retardants, distributed as impurities within the nylon 6 matrix, disrupt the continuity of the polymer molecular chains, becoming stress concentration points and resulting in a significant deterioration of key mechanical properties such as the final fiber's breaking strength and elongation.

[0006] Secondly, to achieve effective flame retardancy, flame retardants need to be uniformly dispersed at the nano or micro scale. However, most current high-efficiency halogen-free flame retardants have high surface energy, making them prone to agglomeration in polymer melts, forming macroscopic agglomerates. These agglomerates not only become weak points in the spinning process, leading to increased pressure and frequent replacement of the spinneret assembly, but also result in low flame retardant efficiency due to uneven dispersion, severely affecting the appearance and quality of the fibers. Furthermore, many high-efficiency halogen-free flame retardants are lightweight, fluffy micro / nano powders with a bulk density far lower than nylon 6 chips. During the feeding process from the hopper to the extruder, they are easily left in the pipeline, causing unstable conveying and fluctuations in the addition ratio, making it difficult to guarantee product quality stability in continuous industrial production.

[0007] To overcome the aforementioned challenges, numerous modification explorations have been conducted within the relevant industry. Chinese patent CN112064138A, filed on August 20, 2020, discloses a method for preparing halogen-free flame-retardant nylon filaments. The method involves uniformly mixing polyamide chips, a halogen-free flame retardant, a compatibilizer, and an antioxidant, followed by extrusion granulation using a twin-screw extruder to obtain a halogen-free flame-retardant masterbatch. The flame retardant comprises graphite-like carbon nitride, silane microcapsules of melamine polyphosphate, and diethyl hypophosphite in a 1:3:2 ratio, a reasonable proportion, and a low total addition amount. This results in good mechanical properties, dyeing properties, and flame-retardant properties. The breaking strength loss of the flame-retardant filament is less than 10%, and it can achieve a small amount of melt dripping. The limiting oxygen index is as high as 34%, demonstrating excellent flame-retardant effects and exhibiting both gas-phase and condensed-phase flame-retardant properties. However, the formula for this process is quite complicated, and the materials used are mostly laboratory-grade, making it difficult to meet the requirements for continuous production. This can lead to problems such as complex processes, high costs, and difficulty in ensuring stable quality.

[0008] Chinese patent publication number CN114197077A, filed on November 26, 2021, discloses a rare-earth flame-retardant nylon fiber and its preparation method, wherein the raw materials include the following components by weight percentage: 91.4 98.1% nylon slices, 0.5 3% rare earth-based flame retardant, 0.2 2% flame retardant synergist, 1 3% nano-inorganic matter, 0.1 0.3% antioxidant and 0.1% 0.3% lubricant. The specific rare-earth-based flame retardant in this invention is compounded with a specific flame retardant synergist to produce a synergistic effect, effectively improving the flame retardant properties of nylon fibers. However, the synthesis method of the rare-earth flame retardant is complex, the reaction time is long, and the yield is relatively low, making industrial application difficult.

[0009] Comprehensive analysis reveals that existing technologies for flame-retardant nylon 6 fibers still face key unresolved technical challenges, namely, how to reconcile the inherent contradictions between flame-retardant efficiency, fiber spinnability and mechanical properties, and process complexity and production costs. Therefore, there is an urgent need to develop a new technical solution employing a highly efficient and thermally stable halogen-free flame-retardant system. This solution would fundamentally address the challenges of uniform dispersion of flame retardants within the nylon 6 matrix and their compatibility with spinning processes. While ensuring excellent and long-lasting flame-retardant performance, it would also maximize the preservation of the inherent superior mechanical properties and processability of nylon 6 fibers, and be compatible with existing industrial continuous production facilities for nylon 6 fibers. Summary of the Invention

[0010] To address the problems existing in the prior art, this invention provides a nylon 6 masterbatch with flame-retardant function, nylon 6 fiber and its preparation method. The nylon 6 fiber has excellent flame-retardant properties, not only with a high limiting oxygen index and significantly reduced dripping phenomenon, but also maintains good breaking strength and elongation. Its mechanical properties are comparable to those of conventional fibers, making it suitable for industrial continuous production.

[0011] The technical solution of the present invention is as follows: One of the objectives of this invention is to provide a method for preparing nylon 6 masterbatch with flame retardant function. The method involves coating a flame retardant, a rare earth synergist, and a dispersant polyether ester polymer in a low-melting-point polyamide wax to form pre-dispersed particles, wherein the flame retardant is a compound of diethyl aluminum hypophosphite and melamine aluminum phosphite; the pre-dispersed particles are then melt-blended and granulated with a nylon 6 matrix to obtain the nylon 6 masterbatch.

[0012] Furthermore, it includes the following steps: S1. Weigh out flame retardant, rare earth synergist and polyamide wax in a ratio of 75:15:10 by mass fraction, mix thoroughly and feed into screw extruder to melt and extrude to form melt strip; S2. Water-cooled plasticized extruded melt strips are granulated to obtain pre-dispersed particles; S3. Weigh out the pre-dispersed particles, dispersant polyether ester polymer, and nylon 6 glossy chips according to the ratio of 10-40:1:89-59 by mass fraction, mix them thoroughly, and then feed them into the screw extruder for melt extrusion to form melt strips. S4. The melt strips extruded by water-cooled plasticizing are granulated to obtain the flame-retardant nylon 6 masterbatch.

[0013] Furthermore, the flame retardant in S1 is composed of a compound of 80 wt% aluminum diethylphosphite and 20 wt% aluminum melamine phosphite, with an average particle size of 800-1200 nm; the rare earth synergist is lanthanum oxide.

[0014] Furthermore, the polyamide wax is Tianshi NEW400.

[0015] Furthermore, the polyether ester polymer is CLiQSPERSE®330 dispersant.

[0016] Furthermore, the extrusion temperature of melt extrusion in S1 is 125°C; the extrusion temperature of melt extrusion in S3 is 220-260°C. The second objective of this invention is to provide a nylon 6 masterbatch with flame retardant function, having a relative viscosity of 2.083-2.329 and a melting point of 219.8-221.6℃.

[0017] Furthermore, in the nylon 6 masterbatch, the content of pre-dispersed particles is 10%-40%, the content of dispersant is 1%, and the content of nylon 6 bright chips is 59%-89%.

[0018] The third objective of this invention is to provide a method for preparing nylon 6 fiber with flame retardant function. By mass fraction, dried nylon 6 masterbatch with flame retardant function and nylon 6 bright chips are fed into a metering pump and a screw extruder in a ratio of 1:4 to melt. The melt is spun into filaments by a component, and then subjected to slow cooling, monomer suction, side blowing cooling, bundle oiling, secondary cooling in the tunnel, stretching and shaping, and finally wound to obtain nylon 6 fiber with flame retardant function.

[0019] Furthermore, the drying temperature is 102℃, the drying time is 24 h, and the melting temperature is 255-265℃. The fourth objective of this invention is to provide a nylon 6 fiber with flame-retardant properties.

[0020] Furthermore, the nylon 6 fiber is a bright, fully drawn SD FDY yarn with a specification of 105D / 24F. Furthermore, the breaking strength is 3.26-3.76 cN / dtex, and the elongation at break is 25.12-28.66%.

[0021] Furthermore, the nylon 6 fiber contains 1.6%-6.6% flame retardant and 0.3%-1.3% rare earth synergist.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention innovatively incorporates a composite flame retardant consisting mainly of aluminum diethyl phosphite and aluminum melamine phosphite, along with the rare earth synergist lanthanum oxide, into a low-melting-point polyamide wax to form pre-dispersed particles. These pre-dispersed particles are then mixed with a nylon matrix and a polyether ester polymeric dispersant for granulation and spinning. This effectively solves the technical problems of low bulk density of halogen-free flame retardants, easy residue in equipment pipelines during addition, and difficulty in accurately controlling the addition ratio of each material. The intermolecular hydrogen bonds in the polyamide wax form a network structure, effectively dispersing the powdered functional additives and ensuring that each component is added uniformly to the nylon 6 matrix in the correct proportion. Furthermore, the low-melting-point polyamide wax volatilizes under the high temperature of melt granulation and does not remain in the masterbatch, thus not affecting the raw material components or subsequent processes.

[0023] 2. The flame-retardant nylon 6 masterbatch designed in this invention has a composite flame-retardant system that can play a synergistic role. The halogen-free flame retardant itself has a high thermal decomposition temperature, does not produce harmful gases during combustion and promotes char formation, and is white in color, so it will not affect the color of the final fiber product. The rare earth synergist lanthanum oxide utilizes its unique 4f electron orbital to exhibit excellent thermal stability during combustion and plays a catalytic esterification role in the combustion reaction, enabling the flame retardant to quickly form a dense and continuous carbon layer on the surface of the polymer material during combustion, further enhancing the flame-retardant effect. The dispersant effectively improves the dispersion uniformity of the additives in the nylon 6 matrix and solves the problem of easy agglomeration of the flame retardant during melt spinning. Together, they make the obtained nylon 6 fiber have good mechanical properties and flame-retardant effect.

[0024] 3. According to the test data of the embodiments, the limiting oxygen index (LOI) of the flame-retardant nylon 6 fiber prepared by the present invention reached 29% to 34%, which is much higher than that of Comparative Example 1 (24%) without flame-retardant masterbatch, and the dripping phenomenon was significantly suppressed. This indicates that it has excellent flame-retardant properties, can effectively delay the spread of fire, and improve the fire safety of the end product. At the same time, the breaking strength of the nylon 6 fiber is maintained at 3.26-3.76 cN / dtex, and the breaking elongation is maintained at a high level of 25.12%-28.66%, which is comparable to the performance of conventional fibers. The evenness (U% and CV%) and oil content are also within the excellent range. The mechanical properties are comparable to those of conventional fibers, which can meet the requirements of subsequent textile processing and practical application for the quality of nylon 6 fiber. Detailed Implementation

[0025] The present invention will be further described below with reference to preferred embodiments. The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values. These ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges. These numerical ranges should be considered as specifically disclosed herein. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0026] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Example 1 This embodiment provides a pre-dispersed compound flame retardant particle, the preparation method of which is as follows: (1) Weigh 75 parts of flame retardant by mass fraction, which includes 60 parts of aluminum diethyl phosphite, 15 parts of aluminum melamine phosphite, 15 parts of lanthanum oxide, and 10 parts of Tianshi NEW400. (2) After mixing the components weighed in step (1), feed them into the screw extruder and melt them at low temperature to form a melt strip. The extrusion temperature is 125℃ and the main machine speed is 550 r / min. (3) The extruded strip from step (2) is water-cooled and plasticized, and then granulated to obtain the pre-dispersed particles of the compound flame retardant.

[0027] Example 2 This embodiment provides a nylon 6 masterbatch with flame-retardant properties, and its preparation method is as follows: (1) Weigh 89 parts of nylon 6 bright chips, 10 parts of pre-dispersed particles prepared in Example 1, and 1 part of CLiQSPERSE®330 dispersant by mass fraction; (2) After mixing the components weighed in step (1), feed them into the screw extruder to melt and form a melt strip. The extrusion temperature is 235℃ and the main machine speed is 550 r / min. (3) The extruded strip from step (2) is water-cooled and plasticized, and then granulated to obtain the nylon 6 masterbatch 1 with flame retardant function.

[0028] Example 3 This embodiment provides a nylon 6 masterbatch with flame-retardant properties, and its preparation method is as follows: (1) Weigh 79 parts of nylon 6 bright chips, 20 parts of pre-dispersed particles prepared in Example 1, and 1 part of CLiQSPERSE®330 dispersant by mass fraction; (2) After mixing the components weighed in step (1), feed them into the screw extruder to melt and form a melt strip. The extrusion temperature is 235℃ and the main machine speed is 550 r / min. (3) The extruded strip from step (2) is water-cooled and plasticized, and then granulated to obtain the nylon 6 masterbatch 2 with flame-retardant function.

[0029] Example 4 This embodiment provides a nylon 6 masterbatch with flame-retardant properties, and its preparation method is as follows: (1) Weigh 69 parts of nylon 6 glossy chips, 30 parts of pre-dispersed particles prepared in Example 1, and 1 part of CLiQSPERSE®330 dispersant by mass fraction; (2) After mixing the components weighed in step (1), feed them into the screw extruder to melt and form a melt strip. The extrusion temperature is 235℃ and the main machine speed is 550 r / min. (3) The extruded strip from step (2) is water-cooled and plasticized, and then granulated to obtain the nylon 6 masterbatch 3 with flame-retardant function.

[0030] Example 5 This embodiment provides a nylon 6 masterbatch with flame-retardant properties, and its preparation method is as follows: (1) Weigh 59 parts of nylon 6 bright chips, 40 parts of pre-dispersed particles prepared in Example 1, and 1 part of CLiQSPERSE®330 dispersant by mass fraction; (2) After mixing the components weighed in step (1), feed them into the screw extruder to melt and form a melt strip. The extrusion temperature is 235℃ and the main machine speed is 550 r / min. (3) The extruded strip from step (2) is water-cooled and plasticized, and then granulated to obtain the nylon 6 masterbatch 4 with flame-retardant function.

[0031] Depending on the actual preparation and operation process, the melting temperature can be adjusted to between 220℃ and 260℃.

[0032] Example 6 This embodiment provides a nylon 6 fiber with flame-retardant properties, and its preparation method is as follows: (1) Dry 80 parts of bright nylon 6 slices and 20 parts of flame retardant nylon 6 masterbatch 1 at 102℃ for 24 h for later use. (2) The dried nylon 6 masterbatch 1 and nylon 6 bright chips are fed into a metering pump and a screw extruder to melt and obtain a melt at a melting temperature of 260°C. The melt is spun into a filament bundle by the component, and then subjected to slow cooling, monomer suction, side blowing cooling, bundle oiling, secondary cooling in the tunnel, stretching and shaping, and finally wound to obtain nylon 6 fiber 1 with flame retardant function.

[0033] Example 7 This embodiment provides a nylon 6 fiber with flame-retardant properties, and its preparation method is as follows: (1) Dry 80 parts of bright nylon 6 slices and 20 parts of flame retardant nylon 6 masterbatch 2 at 102℃ for 24 h for later use. (2) The dried nylon 6 masterbatch 1 and nylon 6 bright chips are fed into a metering pump and a screw extruder to melt and obtain a melt at a melting temperature of 260°C. The melt is spun into a filament bundle by the component, and then subjected to slow cooling, monomer suction, side blowing cooling, bundle oiling, secondary cooling in the tunnel, stretching and shaping, and finally wound to obtain nylon 6 fiber 2 with flame retardant function.

[0034] Example 8 This embodiment provides a nylon 6 fiber with flame-retardant properties, and its preparation method is as follows: (1) Dry 80 parts of bright nylon 6 slices and 20 parts of flame retardant nylon 6 masterbatch 3 at 102℃ for 24 h for later use. (2) The dried nylon 6 masterbatch 1 and nylon 6 bright chips are fed into a metering pump and a screw extruder to melt and obtain a melt at a melting temperature of 260°C. The melt is spun into a filament bundle by the component, and then subjected to slow cooling, monomer suction, side blowing cooling, bundle oiling, secondary cooling in the tunnel, stretching and shaping, and finally wound to obtain nylon 6 fiber 3 with flame retardant function.

[0035] Example 9 This embodiment provides a nylon 6 fiber with flame-retardant properties, and its preparation method is as follows: (1) Dry 80 parts of bright nylon 6 slices and 20 parts of flame retardant nylon 6 masterbatch 4 at 102℃ for 24 h for later use. (2) The dried nylon 6 masterbatch 1 and nylon 6 bright chips are fed into a metering pump and a screw extruder to melt and obtain a melt at a melting temperature of 260°C. The melt is spun into a filament bundle by the component, and then subjected to slow cooling, monomer suction, side blowing cooling, bundle oiling, secondary cooling in the tunnel, stretching and shaping, and finally wound to obtain nylon 6 fiber 4 with flame retardant function.

[0036] Depending on the actual preparation and operation process, the melting temperature can be adjusted to between 255℃ and 265℃.

[0037] Comparative Example 1 This comparative example provides a nylon 6 fiber, which differs from Example 5 only in that flame-retardant nylon 6 masterbatch is not added to the raw material.

[0038] Performance testing 1. Flame retardant performance test The flame retardant properties of the nylon 6 fibers obtained in Examples 6-9 and Comparative Example 1 were tested according to GB / T5455. "Determination of Vertical Damage Length, Smoldering Time and Afterflame Time of Textile Combustion Performance (2014)" The results are shown in Table 1: Table 1 Flame retardant properties of nylon 6 fibers obtained in Examples 6-9

[0039] As shown in Table 1, compared with Comparative Example 1, the nylon 6 fibers obtained in Examples 6-9 exhibited different degrees of flame retardant effect, proving that the preparation method of the present invention is effective.

[0040] 2. Characterization of physicochemical properties and mechanical properties (1) The physicochemical properties of the nylon 6 masterbatches 1-4 prepared in Examples 2-5 were characterized, and the results are shown in Table 2: Table 2. Indicators of Nylon 6 Masterbatch prepared in Examples 2-5

[0041] As shown in Table 2, the Nylon 6 masterbatch 1-4 prepared in Examples 2-5 have normal indicators and can be applied to the industrial production of conventional spinning.

[0042] (2) The mechanical properties of the nylon 6 fibers 1-4 obtained in Examples 6-9 were characterized, and the results are shown in Table 3: Table 3 Mechanical properties of nylon 6 fibers obtained in Examples 6-9

[0043] As shown in Table 3, the various indicators of nylon 6 fibers 1-4 obtained in Examples 6-9 are not significantly different from those of the corresponding conventional nylon fibers, indicating that the flame retardant modification method will not have an adverse effect on the mechanical properties of nylon 6 fiber products.

[0044] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a nylon 6 master batch with a flame retardant function, characterized in that, The flame retardant, the rare earth synergist and the dispersant polyether ester high molecular polymer are proportionally coated in low melting point polyamide wax to form pre-dispersed particles, wherein the flame retardant is a compound of aluminum diethyl hypophosphite and melamine aluminum phosphite; the pre-dispersed particles are melt blended and granulated with a nylon 6 matrix to prepare the nylon 6 master batch.

2. The method for preparing the nylon 6 master batch with the flame-retardant function according to claim 1, characterized in that, It comprises the following steps: S1, the flame retardant, the rare earth synergist and the polyamide wax are proportionally weighed in mass fraction of 75:15:10, and are fed into a screw extruder after being fully mixed to form a melt strip; S2, the melt strip is water-cooled and plasticized, and the pre-dispersed particles are obtained after being cut into particles; S3, the pre-dispersed particles, the dispersant polyether ester high molecular polymer and the nylon 6 bright chip are proportionally weighed in mass fraction of 10-40:1:89-59, and are fed into a screw extruder after being fully mixed to form a melt strip; S4, the melt strip is water-cooled and plasticized, and the flame-retardant nylon 6 master batch is obtained after being cut into particles.

3. The method for preparing a flame-retardant nylon 6 masterbatch according to claim 2, characterized in that, The flame retardant in S1 is composed of a compound of 80 wt% aluminum diethyl hypophosphite and 20 wt% melamine aluminum phosphite, and the average particle size is 800-1200 nm; the rare earth synergist is lanthanum oxide.

4. The method according to claim 2, wherein the method is characterized by, The extrusion temperature of the melt extrusion in S1 is 125℃; the extrusion temperature of the melt extrusion in S3 is 220-260℃.

5. The nylon 6 master batch with flame retardant function prepared by the method according to any one of claims 1 to 4, characterized in that, The relative viscosity is 2.083-2.329, and the melting point is 219.8-221.6℃.

6. The nylon 6 master batch with flame retardant function according to claim 5, characterized in that, In the nylon 6 master batch, the content of the pre-dispersed particles is 10%-40%, the content of the dispersant is 1%, and the content of the nylon 6 bright chip is 59%-89%.

7. A method for preparing a nylon 6 fiber having a flame retardant function using the nylon 6 master batch according to claim 5 or 6, characterized by, The dry nylon 6 master batch with flame retardant function and the nylon 6 bright chip are proportionally put into a metering pump and a screw extruder in mass fraction of 1:4 to melt, and the melt is formed into a filament by a component spinneret, then is slowly cooled, monomer suctioned, side blown and cooled, bundled and oiled, secondarily cooled in a duct, stretched and shaped, and finally wound into a nylon 6 fiber with flame retardant function.

8. The method of claim 7, wherein the nylon 6 fiber having a flame retardant function is prepared by adding 0.1 to 5 parts by weight of the compound of formula (1) to 100 parts by weight of nylon 6. The drying temperature is 102℃, and the drying time is 24 h; the melting temperature is 255-265℃.

9. The nylon 6 fiber with flame retardant function prepared by the method according to any one of claims 7 or 8, characterized in that, The nylon 6 fiber is a bright fully drawn yarn SD FDY with a specification of 105D / 24F.

10. The nylon 6 fiber with a flame retardant function according to claim 9, characterized in that, The breaking strength is 3.26-3.76 cN / dtex, and the breaking elongation is 25.12-28.66%.

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