High-temperature-resistant and flame-retardant nylon brush wire and preparation method thereof

Abstract

The invention belongs to the technical field of nylon materials, and particularly discloses a high-temperature-resistant and flame-retardant nylon brush wire and a preparation method thereof, and the high-temperature-resistant and flame-retardant nylon brush wire comprises the following components by weight: 80-90 parts of PA6; 8-10 parts of modified carbon fiber; 0.3 to 0.5 part of an initiator; 6-8 parts of a toughening agent; 0.2 to 0.3 part of an antioxidant; wherein the modified carbon fiber is a vinyl phosphate-containing ionic liquid modified carbon fiber material, and the high-temperature-resistant and flame-retardant nylon brush wire provided by the invention has excellent high temperature resistance and flame retardance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nylon materials, and particularly relates to a high-temperature-resistant and flame-retardant nylon brush wire and a preparation method thereof. BACKGROUND

[0002] Polyamide 6 (PA6, nylon 6) is a commonly used engineering plastic, which has the advantages of high strength, good toughness, wear resistance and self-lubricating property, and is widely used in the fields of automobile manufacturing (such as engine peripheral parts and intake manifolds), electronics and electrical appliances (such as connectors and switches), and textiles (such as clothing and carpet fibers).

[0003] However, with the increasing requirements of various industries on the performance of materials, the limitations of PA6 are also highlighted. In a high-temperature environment, the mechanical properties of PA6 decrease significantly, and the heat distortion temperature is low, which limits its application in scenarios with extremely high heat resistance requirements. At the same time, PA6 has poor flame retardancy, is easy to burn when exposed to fire, and releases a large amount of smoke and toxic gases during combustion, which threatens personal safety and the environment. Therefore, improving the high-temperature resistance and flame retardancy of PA6 has become an important research topic.

[0004] The traditional methods for improving the high-temperature resistance and flame retardancy of PA6 mainly include adding inorganic fillers and organic flame retardants.

[0005] Among them, adding inorganic fillers such as glass fibers and carbon fibers can improve the mechanical properties and heat distortion temperature, but will make the processing performance worse and increase the density, which is not conducive to lightweight design. Adding organic flame retardants: halogen-based flame retardants are highly efficient in flame retardation but release toxic gases, limiting their application; phosphorus-based and nitrogen-based flame retardants are low in smoke and toxicity, but a single flame retardant cannot simultaneously achieve high efficiency, low smoke and low toxicity, and good processing performance, and often needs to be used in combination.

[0006] Therefore, it is urgent to develop a new high-temperature-resistant and flame-retardant nylon brush wire to solve the above problems. SUMMARY

[0007] Based on the deficiencies of the prior art, the application provides a high-temperature-resistant and flame-retardant nylon brush wire and a preparation method thereof. The nylon brush wire prepared by the method has excellent high-temperature resistance and flame retardancy.

[0008] In order to solve the above technical problems and achieve the above technical effects, the application provides a high-temperature-resistant and flame-retardant nylon brush wire, which comprises the following components by weight: PA6 80-90 parts; Modified carbon fiber 8-10 parts; Initiator 0.3-0.5 parts; Toughening agent 6-8 parts; Antioxidant 0.2-0.3 parts; Among them, the modified carbon fiber is a carbon fiber material modified with vinyl phosphate type ionic liquid.

[0009] This invention provides a high-temperature resistant, flame-retardant nylon brush bristle. PA6 serves as the matrix material, endowing the nylon brush bristle with fundamental physical and chemical properties. The surface of the vinyl phosphate-modified carbon fiber material (CF-IL) is grafted with active sites on the PA6 molecular chains via vinyl free radical polymerization, forming chemical bonds and significantly enhancing interfacial bonding. Furthermore, the phosphate groups decompose at high temperatures to generate phosphoric acid, polyphosphoric acid, and other substances, which catalyze the dehydration of the PA6 matrix into carbon, forming a dense carbon layer that isolates oxygen and heat conduction, greatly improving the flame-retardant rating of the brush bristle and making it less prone to combustion when exposed to an ignition source, thus reducing the risk of fire accidents. Moreover, the thermal conductivity of CF-IL is much higher than that of PA6, which can quickly disperse localized heat and avoid degradation caused by heat concentration. Simultaneously, the phosphate carbon layer can delay matrix decomposition, increasing the thermal decomposition temperature of the composite material.

[0010] Preferably, the method for preparing the vinyl phosphate-containing ionic liquid includes the following steps: S1, diethyl hydroxymethylphosphonate and chloroacetyl chloride react in the presence of triethylamine to form the first intermediate product; S2. The first intermediate reacts with 1-vinylimidazole, and after filtration, washing, and drying, a chloride-type ionic liquid is obtained. S3, a chloride-type ionic liquid, reacts with sodium hypophosphite, and after vacuum distillation, filtration, and drying, a vinyl phosphate-type ionic liquid is obtained.

[0011] Preferably, the specific steps of S1 are as follows: under water bath conditions of 60-70℃, hydroxyphosphonate and chloroacetyl chloride are reacted in the presence of triethylamine, and after the reaction is completed, the mixture is filtered and washed to obtain the first intermediate product.

[0012] Preferably, the method for preparing the modified carbon fiber includes the following steps: T1. Dissolve the vinyl phosphate-containing ionic liquid in N,N-dimethylformamide, add an initiator, and pass an inert gas through it for deoxygenation treatment to obtain a mixed solution; T2. The pretreated carbon fiber is immersed in a mixed solution and subjected to free radical polymerization under heating conditions to graft vinyl groups in the ionic liquid onto the active sites on the carbon fiber surface. After the reaction is completed, post-treatment is performed to obtain modified carbon fiber.

[0013] Preferably, the hydroxyphosphonate is one of diethyl hydroxymethylphosphonate or dimethyl 2-hydroxyethylphosphonate. More preferably, the hydroxyphosphonate is diethyl hydroxymethylphosphonate, in which the hydroxymethyl group (-CH2OH) reacts directly with the acyl chloride group (-COCl) of chloroacetyl chloride to generate diethyl α-(chloroacetoxy)methylphosphonate. This reaction pathway is well-defined, has few side reactions, is simple to purify, and has a high yield.

[0014] Preferably, the molar ratio of the hydroxyphosphonate to chloroacetyl chloride is 1:(1-1.2); the molar ratio of the first intermediate to 1-vinylimidazole is 1:(1-1.2).

[0015] In this invention, the molar ratio of the hydroxyphosphonate to chloroacetyl chloride is 1:(1-1.2), and the molar ratio of the first intermediate to 1-vinylimidazole is 1:(1-1.2), which ensures that the raw materials react fully and improves the reaction yield.

[0016] Preferably, the mass ratio of PA6 to modified carbon fiber is (8-9):1.

[0017] In this invention, the mass ratio of PA6 to modified carbon fiber is set to (8-9):1. The modified carbon fiber, by introducing flame-retardant elements, forms a dense char layer during combustion, isolating oxygen and heat transfer. When the mass ratio is (8-9):1, an appropriate amount of modified carbon fiber can significantly improve the limiting oxygen index (LOI) and flame retardant rating of the composite material. Within this range, the modified carbon fiber does not reach the critical agglomeration threshold, and the melt viscosity is moderate, allowing for smooth processing via a twin-screw extruder or injection molding machine, avoiding fiber breakage or surface defects. Furthermore, within this range, the modified carbon fiber content can significantly improve the performance of nylon brush filaments while avoiding a surge in cost due to excessive addition.

[0018] Preferably, the toughening agent is one of maleic anhydride grafted elastomer or ethylene-octene copolymer.

[0019] In this invention, the interfacial compatibility with PA6 is enhanced by adding a maleic anhydride-grafted elastomer as a toughening agent. This improved compatibility allows the toughening agent to be more uniformly dispersed in the PA6 matrix, forming an island structure or network structure, effectively absorbing impact energy and significantly improving the material's impact resistance. Alternatively, ethylene-octene copolymer (POE) is a highly elastic toughening agent with a low glass transition temperature (Tg). The octene units in its molecular chain provide excellent flexibility and tear resistance. POE blended with PA6 can form a soft-hard phase separation structure, significantly reducing brittleness while maintaining the rigidity of PA6, making the brush bristles less prone to breakage in low-temperature or high-frequency applications. Choosing either of these two toughening agents can improve the impact resistance of PA6.

[0020] Preferably, the initiator is benzoyl peroxide (BPO).

[0021] In this invention, benzoyl peroxide (BPO) is selected as an initiator, which can significantly improve the processing performance, molecular weight controllability, and flame retardant modification effect of brush filaments by optimizing the polymerization reaction path and product structure.

[0022] The present invention also provides a method for preparing the above-mentioned high-temperature resistant and flame-retardant nylon brush bristles, comprising the following steps: (1) Dissolve the initiator in acetone at a mass ratio of 1:5, stir evenly, add the modified carbon fiber material containing vinyl phosphate ionic liquid, and ultrasonically disperse for 30-40 minutes to form a uniform initiator-modified carbon fiber suspension. (2) Premix 0.2-0.3 parts by weight of antioxidant 1010 with 80-90 parts by weight of PA6, stir at 500-1000 rpm for 5-8 minutes using a high-speed mixer, then transfer to a double cone mixer and mix for 20-30 minutes until uniform to form antioxidant masterbatch; (3) A twin-screw extruder is used to add antioxidant masterbatch to the main feed hopper for melting and plasticization; when the PA6 melt passes through the side feed port, toughening agent is added and initially mixed to form a matrix; in the mixing section, initiator-modified carbon fiber suspension is injected through a liquid metering pump, and uniform dispersion and in-situ grafting reaction are achieved by utilizing the high shear zone of the screw. After the melt is extruded through the die head, it is drawn and heat-set to obtain high-temperature resistant and flame-retardant nylon brush filaments.

[0023] The preparation method provided by this invention involves dissolving an initiator in acetone and then dispersing it with vinyl phosphate-modified carbon fibers using ultrasonication to form a suspension. This avoids fiber agglomeration and excessively high local concentrations of the initiator caused by direct mixing. Furthermore, pre-mixing antioxidant 1010 with PA6 and then stirring at high speed to prepare antioxidant masterbatch allows for more uniform dispersion of the antioxidant in PA6, effectively preventing oxidative degradation of PA6 during processing and use, and extending the service life of the brush filaments. In addition, the initiator-modified carbon fiber suspension is injected into the mixing section using a liquid metering pump, utilizing the high-shear zone of the screw to achieve uniform dispersion and in-situ grafting reaction. This in-situ grafting method enables the vinyl groups in the modified carbon fibers to form chemical bonds with the PA6 molecular chains, enhancing interfacial bonding and allowing the modified carbon fibers to exist more stably within the PA6 matrix, fully utilizing their flame-retardant and high-temperature resistance properties, and significantly improving the flame-retardant rating and heat resistance stability of the brush filaments.

[0024] Preferably, when a twin-screw extruder is used in step (3), the screw diameter is 35-50 mm, the length-to-diameter ratio is 40:1, and the temperature gradient is set as follows: Zone 1 (feeding section): 200-210℃; Zone 2 (melting section): 230-250℃; Zone 3 (mixing section): 250-260℃; Die head: 265-275℃; Screw speed: 300-350 rpm; Vacuum degree: the vacuum pump at the rear end of the die head is used to evacuate to ≤-0.08 MPa.

[0025] The present invention has the following beneficial effects: (1) The present invention provides a high-temperature resistant and flame-retardant nylon brush bristle, wherein PA6 is used as the matrix material, which endows the nylon brush bristle with basic physical and chemical properties. The surface of the vinyl phosphate-modified carbon fiber material (CF-IL) is grafted with active sites on the PA6 molecular chain through vinyl free radical polymerization, forming chemical bonds and significantly enhancing the interfacial bonding force. In addition, the phosphate groups decompose at high temperature to generate substances such as phosphoric acid and polyphosphoric acid, which can catalyze the dehydration of the PA6 matrix to form carbon, forming a dense carbon layer, which isolates oxygen and heat conduction, greatly improving the flame retardant grade of the brush bristle, making it less likely to burn when it encounters a fire source, and reducing the risk of fire accidents. Moreover, the thermal conductivity of CF-IL is much higher than that of PA6, which can quickly disperse local heat and avoid degradation caused by heat concentration. At the same time, the phosphate carbon layer can delay the decomposition of the matrix, increase the thermal decomposition temperature of the composite material, and give the nylon brush bristle excellent high-temperature resistance.

[0026] (2) The method for preparing high temperature resistant and flame retardant nylon bristles provided by the present invention is simple in the whole preparation process, reduces material loss and time waste in intermediate links, improves production efficiency, is conducive to large-scale industrial production, thereby reducing production costs and improving the market competitiveness of products. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Unless otherwise specified, all raw materials used in the following embodiments are commercially available. The toughening agent is maleic anhydride-grafted elastomer (POE-g-MAH), and the antioxidant is antioxidant 1010. Example 1

[0029] This embodiment provides a method for preparing a vinyl phosphate-containing ionic liquid, comprising the following steps: S1. In a 250 mL three-necked flask equipped with a magnetic stirrer, reflux condenser, constant pressure dropping funnel, and N2 ball, add 16.8 g (0.10 mol) of diethyl hydroxymethylphosphonate and 100 mL of chloroform. Start the magnetic stirrer and add 12.13 g (0.12 mol) of triethylamine. Stir thoroughly for 10 minutes until homogeneous. Then heat in a water bath. When the temperature reaches 35 °C, slowly add 13.55 g (0.12 mol) of chloroacetyl chloride (CAC) dropwise over 1 hour. Then raise the temperature to 60 °C and continue the reaction for 6 hours. Remove the solvent under reduced pressure. Wash the obtained product several times with deionized water and then dry it in a vacuum drying oven at 70 °C for 12 hours to obtain the first intermediate product.

[0030] S2. In a 250 mL three-necked flask equipped with a magnetic stirrer, a reflux condenser, and an N2 ball, add 24.46 g (0.1 mol) of the first intermediate product and 100 mL of acetonitrile. Then, add 11.3 g (0.12 mol) of 1-vinylimidazole dropwise to the above solution. Heat to 70 °C and react for 12 h. Then filter, wash the obtained product several times with acetonitrile, and dry it in a vacuum drying oven at 70 °C for 12 h to obtain a chloride salt type ionic liquid.

[0031] S3. Place the chloride-type ionic liquid (0.1 mol) obtained in step S2 into a three-necked flask, add 200 mL of distilled water, and stir at room temperature until fully dissolved. Then, mix 9.79 g (0.11 mol) of sodium hypophosphite with 50 mL of distilled water and add it dropwise to the reaction system. Heat to 80 °C for 24 h. Remove the solvent by rotary evaporation to obtain the crude product. Add anhydrous methanol to the product, filter to remove sodium chloride, remove anhydrous methanol by rotary evaporation, centrifuge to remove excess sodium hypophosphite, and vacuum dry at 60 °C for 24 h to obtain a yellow transparent liquid product, which is the vinyl phosphate-containing ionic liquid A, with the structural formula: [C5H6N2-CH2CO-CH2P(O)(OEt)2]. + H2PO2 - . Example 2

[0032] This embodiment provides a method for preparing a vinyl phosphate-containing ionic liquid, comprising the following steps: S1. In a 250 mL three-necked flask equipped with a magnetic stirrer, reflux condenser, constant pressure dropping funnel, and N2 ball, add 15.4 g (0.1 mol) of dimethyl 2-hydroxyethylphosphonate and 100 mL of chloroform. Start the magnetic stirrer and add 12.13 g (0.12 mol) of triethylamine. Stir thoroughly for 10 minutes until homogeneous. Then heat in a water bath. When the temperature reaches 35 °C, slowly add 13.55 g (0.12 mol) of chloroacetyl chloride (CAC) dropwise over 1 hour. Then heat to 70 °C and continue the reaction for 8 hours. Remove the solvent under reduced pressure. Wash the obtained product several times with deionized water and then dry it in a vacuum drying oven at 70 °C for 12 hours to obtain the first intermediate product.

[0033] S2. In a 250 mL three-necked flask equipped with a magnetic stirrer, a reflux condenser, and an N2 ball, add 23.05 g (0.10 mol) of the first intermediate product and 100 mL of acetonitrile. Then, add 11.3 g (0.12 mol) of 1-vinylimidazole dropwise to the above solution. Heat the mixture to 70 °C and react for 12 h. After filtration, wash the obtained product several times with acetonitrile and dry it in a vacuum drying oven at 70 °C for 12 h to obtain a chloride-type ionic liquid.

[0034] S3. Place 0.1 mol of chloride-type ionic liquid in a three-necked flask, add 200 mL of distilled water, and stir at room temperature until fully dissolved. Then, mix 9.79 g (0.11 mol) of sodium hypophosphite with 50 mL of distilled water and add the mixture dropwise to the reaction system. Heat to 80 °C for 24 h. Remove the solvent by rotary evaporation to obtain the crude product. Add anhydrous methanol to the product, filter to remove sodium chloride, remove anhydrous methanol by rotary evaporation, and centrifuge to remove excess sodium hypophosphite. Dry under vacuum at 60 °C for 24 h to obtain a yellow transparent liquid product, which is vinyl phosphate-containing ionic liquid B, with the structural formula: [C5H6N2-CH2CO-CH2P(O)(OEt)2]. + H2PO2 - . Example 3

[0035] This embodiment provides a method for preparing modified carbon fiber, including the following steps: TI. The vinyl phosphate-containing ionic liquid A (5g) prepared in Example 1 was dissolved in N,N-dimethylformamide (DMF, 100mL), and the initiator benzoyl peroxide (BPO, 0.1g) was added. Nitrogen gas was purged for 30 minutes to remove oxygen and obtain a mixed solution.

[0036] T2. Immerse the pretreated carbon fiber (5g) in the mixed solution and stir at 70°C for 24 hours to allow the vinyl group to undergo free radical polymerization with the active sites on the carbon fiber surface. After the reaction is complete, wash the product three times with DMF and ethanol to remove unreacted ionic liquid. Dry under vacuum at 60°C for 12 hours to obtain modified carbon fiber (CF-IL-A).

[0037] The specific method for pretreating carbon fibers is as follows: immerse the carbon fibers in a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, and treat them at a temperature of 80°C for 3 hours to form micropores and oxygen-containing groups on the surface through an oxidation reaction. Example 4

[0038] This embodiment provides a method for preparing modified carbon fiber, including the following steps: TI. The vinyl phosphate-containing ionic liquid B (5g) prepared in Example 2 was dissolved in N,N-dimethylformamide (DMF, 100mL), and the initiator benzoyl peroxide (BPO, 0.1g) was added. Nitrogen gas was purged for 30 minutes to remove oxygen and obtain a mixed solution.

[0039] T2. Immerse 5g of the pretreated carbon fiber into the above solution and stir at 70°C for 24 hours to allow the vinyl group to undergo free radical polymerization with the active sites on the carbon fiber surface. After the reaction, wash the product three times with DMF and ethanol to remove unreacted ionic liquid. Dry under vacuum at 60°C for 12 hours to obtain modified carbon fiber (CF-IL-B). The specific method for pretreating the carbon fiber is the same as in Example 3. Example 5

[0040] This embodiment provides a method for preparing high-temperature resistant, flame-retardant nylon brush bristles, including the following steps: (1) Dissolve the initiator in acetone at a mass ratio of 1:5, stir evenly, add vinyl phosphate type ionic liquid modified carbon fiber (CF-IL-A), and sonicate for 30 minutes at an ultrasonic power of 200W and a frequency of 40kHz to form a uniform initiator-modified carbon fiber (CF-IL-A) suspension.

[0041] (2) Premix antioxidant 1010 with PA6 according to the required weight parts, stir at 800 rpm for 8 minutes using a high-speed mixer, transfer to a double cone mixer, and mix for 20 minutes until uniform to form antioxidant masterbatch. Before step (2), PA6 resin should be placed in a vacuum drying oven and dried at 100°C for 8 hours to ensure that the moisture content is below 0.05% to avoid hydrolysis and degradation during melt processing.

[0042] (3) A twin-screw extruder is used to add antioxidant masterbatch to the main feed hopper for melting and plasticization; when the PA6 melt passes through the side feed port, toughening agent is added and initially mixed to form the matrix; in the mixing section, initiator-modified carbon fiber (CF-IL-A) suspension is injected through a liquid metering pump, and uniform dispersion and in-situ grafting reaction are achieved by utilizing the high shear zone of the screw. After the melt is extruded through the die head, it is drawn and heat-set to obtain high-temperature resistant and flame-retardant nylon brush filaments. The specific composition of each raw material is shown in Table 1 below.

[0043] The toughening agent is a maleic anhydride-grafted elastomer (such as POE-g-MAH), which needs to be dried in advance to a moisture content of less than 0.1% to prevent bubbles from forming during processing.

[0044] The screw has a diameter of 35mm and a length-to-diameter ratio of 40:1. The temperature gradient is set as follows: Zone 1 (feeding section): 210℃; Zone 2 (melting section): 240℃; Zone 3 (mixing section): 260℃; Die head: 265℃; Screw speed: 300rpm; Vacuum degree: the vacuum pump at the rear of the die head is used to evacuate to -0.08MPa.

[0045] The specific methods for wire drawing and heat setting are as follows: After the wire drawing melt is extruded through the die head, it is cooled in a water cooling tank (water temperature 20℃) to form nascent filaments. The nascent filaments are then passed through a stretching and traction device in the following stages: Preheating zone: hot air box temperature 120℃, preheating for 10 seconds; Stretching zone: hot air box temperature 150℃, traction roller speed gradient set to 20r / min→80r / min→90r / min, to achieve multi-stage stretching (total stretching ratio 5:1); Setting zone: hot air box temperature 160℃, held for 30 seconds to stabilize the filament shape; and then wound at a speed of 50m / min to obtain high-temperature resistant, flame-retardant nylon brush filaments.

[0046] The preparation methods in Examples 6-8 are the same as those in Example 5, except that the specific composition of each raw material is shown in Table 1 below.

[0047] Comparative Example 1 This comparative example provides a method for preparing nylon brush bristles, comprising the following steps: (1) Premix antioxidant 1010 and PA6 according to the required weight parts, and stir for 8 minutes at 1000 rpm using a high-speed mixer to form antioxidant masterbatch.

[0048] Before proceeding with step (1), the PA6 resin must be placed in a vacuum drying oven and dried at 100°C for 8 hours to ensure that the moisture content is below 0.05% and to avoid hydrolysis and degradation during melt processing.

[0049] (2) Using a twin-screw extruder, antioxidant masterbatch is added to the main feed hopper for melting and plasticizing; when the PA6 melt passes through the side feed port, toughening agent is added, and the shearing action of the twin-screw extruder is used to achieve preliminary mixing and form a uniform matrix. The matrix melt is extruded through the die head and then drawn and heat-set (the method is the same as in Example 5) to obtain nylon brush filaments.

[0050] The toughening agent is a maleic anhydride-grafted elastomer (such as POE-g-MAH), which needs to be dried in advance to a moisture content of less than 0.1% to prevent bubbles from forming during processing.

[0051] In addition, the screw diameter is 35mm, the length-to-diameter ratio is 40:1, and the temperature gradient is set as follows: Zone 1 (feeding section): 210℃; Zone 2 (melting section): 240℃; Zone 3 (mixing section): 260℃; Die head: 265℃; Screw speed: 300rpm; Vacuum degree: vacuum pump at the rear of the die head is used to evacuate to -0.08MPa.

[0052] The specific composition of each raw material is shown in Table 1 below.

[0053] Comparative Example 2 This embodiment provides a method for preparing high-temperature resistant, flame-retardant nylon brush bristles, including the following steps: (1) Premix antioxidant 1010 and PA6 according to the required weight parts, and stir at 800 rpm for 8 minutes using a high-speed mixer to form antioxidant masterbatch.

[0054] Before proceeding with step (1), the PA6 resin must be placed in a vacuum drying oven and dried at 100°C for 8 hours to ensure that the moisture content is below 0.05% and to avoid hydrolysis and degradation during melt processing.

[0055] (2) Using a twin-screw extruder, antioxidant masterbatch is added to the main feed hopper for melting and plasticizing; when the PA6 melt passes through the side feed port, toughening agent is added and initially mixed to form a matrix; modified carbon fiber (CF-IL-A) is added in the mixing section, and uniform dispersion is achieved by utilizing the high shear zone of the screw. After the melt is extruded through the die head, it is drawn and heat-set (the method is the same as in Example 5) to obtain nylon brush filaments.

[0056] The toughening agent is maleic anhydride grafted elastomer (POE-g-MAH), which needs to be dried in advance to a moisture content of less than 0.1% to prevent bubbles from forming during processing.

[0057] Additionally, the screw diameter is 35mm, the length-to-diameter ratio is 40:1, and the temperature gradient is set as follows: Zone 1 (feeding section): 210℃; Zone 2 (melting section): 240℃; Zone 3 (mixing section): 260℃; Die head: 260℃; Screw speed: 300rpm; Vacuum degree: vacuum pump at the rear of the die head evacuates to -0.08MPa. The specific composition of each raw material is shown in Table 1 below.

[0058] The preparation methods of Comparative Examples 3 and 4 are the same as those of Example 5, except that the specific composition of each raw material is shown in Table 1 below.

[0059] Table 1, Weight proportions of each raw material component in Examples 5-8 and Comparative Examples 1-4 nylon modified carbon fiber initiator toughening agent antioxidant 1010 PA6 CF-IL-A CF-IL-B BPO / / example 5 80 10 0 0.3 6 0.2 example 6 85 10 0 0.4 7 0.3 example 7 90 10 0 0.5 8 0.3 example 8 85 0 10 0.5 7 0.3 comparative example 1 85 0 0 0 7 0.3 comparative example 2 85 10 0 0 7 0.3 comparative example 3 85 15 0 0.4 7 0.3 comparative example 4 85 3 0 0.4 7 0.3

[0060] Test example: The performance of the samples obtained in Examples 5-8 and Comparative Examples 1-4 was tested, and the test results are shown in Table 2 below.

[0061] Test method: The performance of the samples prepared in Examples 5-8 and Comparative Examples 1-4 was tested respectively. The tensile strength was tested according to GB 1040-79 standard, the flexural strength was tested according to GB / T 9341-2008 standard, the impact strength was tested according to GB / T1843-2008 standard, the flame retardancy rating was tested according to UL-94 standard, and the thermal decomposition temperature was tested by thermogravimetric analysis (TGA).

[0062] The test results are shown in Table 2: Table 2. Properties of the nylon brush filaments prepared in Examples 5-8 and Comparative Examples 1-4 tensile strength / mPa bending strength / mPa impact strength / (KJ / m 2 ) flame retardant rating UL-94 thermal decomposition temperature / °c example 5 200 270 43 V-0 312 example 6 204 271 45 V-0 320 example 7 202 272 44 V-0 313 example 8 203 271 44 V-0 315 comparative example 1 75 100 35 V-2 210 comparative example 2 180 250 40 V-1 301 comparative example 3 220 280 43 V-0 318 comparative example 4 165 215 42 V-1 305

[0063] As can be seen from the data in Table 2, the nylon brush filaments prepared in Examples 5-8 of the present invention have excellent flame retardant and high temperature resistance properties, as well as excellent mechanical properties.

[0064] As can be seen from the data in Example 6 and Comparative Example 1, without the addition of modified carbon fiber, its flame retardancy, high temperature resistance and mechanical properties are far inferior to those of the nylon brush filaments prepared in Example 6.

[0065] As can be seen from the data of Example 6 and Comparative Example 2, although adding modified carbon fiber without adding an initiator improves the mechanical properties, flame retardancy, and high-temperature resistance of nylon brush filaments to some extent, the mechanical properties, flame retardancy, and high-temperature resistance of nylon brush filaments prepared in Comparative Example 2 are much lower than those prepared in Example 6. This may be because without an initiator, the vinyl groups in the modified carbon fiber cannot undergo grafting reactions with the active sites on the PA6 molecular chain, resulting in nylon brush filaments with inferior flame retardancy and high-temperature resistance compared to those prepared in Example 6.

[0066] Data from Example 6, Comparative Examples 3 and 4 show that when too little modified carbon fiber is added, the flame retardant and high-temperature resistance of the prepared nylon brush filaments are improved, but the required flame retardant rating cannot be achieved. If too much modified carbon fiber is added, although the flame retardant and high-temperature resistance are good, the high carbon fiber content may lead to injection molding difficulties. Therefore, the amount of vinyl phosphate-containing ionic liquid added must be moderate to ensure that the nylon brush filaments possess excellent flame retardant and high-temperature resistance, as well as excellent mechanical properties.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature resistant, flame-retardant nylon brush bristle, characterized in that, The components include the following parts by weight: PA6 80-90 servings; 8-10 parts of modified carbon fiber; Initiator 0.3-0.5 parts; 6-8 parts toughening agent; Antioxidant 0.2-0.3 parts; Among them, the modified carbon fiber is a carbon fiber material modified with vinyl phosphate type ionic liquid.

2. The high-temperature resistant, flame-retardant nylon brush bristles according to claim 1, characterized in that, The preparation method of the vinyl phosphate-containing ionic liquid includes the following steps: S1, hydroxyphosphonate and chloroacetyl chloride react in the presence of triethylamine to form the first intermediate; S2. The first intermediate reacts with 1-vinylimidazole, and after filtration, washing, and drying, a chloride-type ionic liquid is obtained. S3, a chloride-type ionic liquid, and sodium hypophosphite reacted, followed by vacuum distillation, filtration, and drying to obtain a vinyl phosphate-type ionic liquid.

3. The high-temperature resistant, flame-retardant nylon brush bristles according to claim 2, characterized in that, The method for preparing the modified carbon fiber includes the following steps: T1. Dissolve the vinyl phosphate-containing ionic liquid in N,N-dimethylformamide, add an initiator, and then deoxygenate it by passing an inert gas to obtain a mixed solution; T2. The pretreated carbon fiber is immersed in a mixed solution and subjected to free radical polymerization under heating conditions to graft vinyl groups in the ionic liquid onto the surface active sites of the pretreated carbon fiber. After the reaction is completed, the modified carbon fiber is obtained through post-treatment.

4. The high-temperature resistant, flame-retardant nylon brush bristles according to claim 2, characterized in that, The hydroxyphosphonate is one of diethyl hydroxymethylphosphonate or dimethyl 2-hydroxyethylphosphonate.

5. The high-temperature resistant, flame-retardant nylon brush bristles according to claim 2, characterized in that, The molar ratio of the hydroxyphosphonate to chloroacetyl chloride is 1:(1-1.2); the molar ratio of the first intermediate to 1-vinylimidazole is 1:(1-1.2).

6. The high-temperature resistant, flame-retardant nylon brush bristles according to claim 1, characterized in that, The mass ratio of PA6 to modified carbon fiber is (8-9):

1.

7. The high-temperature resistant, flame-retardant nylon brush bristles according to claim 1, characterized in that, The toughening agent is one of maleic anhydride grafted elastomer or ethylene-octene copolymer.

8. A high-temperature resistant, flame-retardant nylon brush bristle according to claim 1 or 3, characterized in that, The initiator is benzoyl peroxide.

9. A method for preparing high-temperature resistant, flame-retardant nylon brush bristles according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Dissolve the initiator in acetone at a mass ratio of 1:5, stir evenly, add the modified carbon fiber material containing vinyl phosphate ionic liquid, and ultrasonically disperse for 30-40 minutes to form a uniform initiator-modified carbon fiber suspension. (2) Premix 0.2-0.3 parts by weight of antioxidant 1010 with 80-90 parts by weight of PA6, stir at 500-1000 rpm for 5-8 minutes using a high-speed mixer, transfer to a double cone mixer, mix for 20-30 minutes until uniform, and form antioxidant masterbatch; (3) Using a twin-screw extruder, antioxidant masterbatch is added to the main feed hopper for melting and plasticization; when the PA6 melt in the antioxidant masterbatch passes through the side feed port, toughening agent is added and initially mixed to form a matrix; in the mixing section, initiator-modified carbon fiber suspension is injected through a liquid metering pump, and uniform dispersion and in-situ grafting reaction are achieved by utilizing the high shear zone of the screw. After the melt is extruded through the die head, it is drawn and heat-set to obtain high-temperature resistant and flame-retardant nylon brush filaments.

10. The method for preparing high-temperature resistant and flame-retardant nylon brush bristles according to claim 9, characterized in that, When using a twin-screw extruder in step (3), the screw diameter is 35-50mm, the length-to-diameter ratio is 40:1, and the temperature gradient is set as follows: feeding section 1: 200-210℃; melting section 2: 230-250℃; mixing section 3: 250-260℃; die head: 265-275℃; screw speed: 300-350rpm; vacuum degree: vacuum pump at the rear end of the die head is used to evacuate to ≤-0.08MPa.