Enhanced high temperature nylon composite and method of making same

Abstract

The application relates to the technical field of high polymer materials, in particular to a reinforced high-temperature nylon composite material and a preparation method thereof. The high-temperature nylon composite material comprises the following components in parts by weight: a ternary nylon matrix resin 60-85 parts; inorganic reinforcing fibers 15-40 parts; maleic anhydride grafted SEBS 2-8 parts; 3-trifluoroacetyl oxypropyl trimethoxysilane 0.3-2.0 parts; functional additives 1-5 parts; the functional additives comprise: an antioxidant 0.2-1.5 parts, a nucleating agent 0.1-1 part and a lubricant 0.2-2 parts. According to the application, the in-situ interface is synergistically modified, the long-term reliability and insulation performance of the material under extreme working conditions are greatly improved, and the mechanical properties and heat resistance are not significantly sacrificed.

Description

Technical Field

[0001] This application belongs to the technical field of polymer materials, and particularly relates to an enhanced high-temperature nylon composite material and its preparation method. Background Technology

[0002] High-temperature nylon (HTN) has become a core structural material for the three-electric system of new energy vehicles due to its excellent heat resistance, mechanical properties, and processability. Among them, the PA66 / PA6T / PA9T ternary blend system achieves a good balance between cost, heat resistance, and low moisture absorption through complementary advantages, and is currently the mainstream high-temperature nylon system.

[0003] To meet mechanical strength requirements, high-temperature nylon is commonly reinforced with inorganic reinforcing fibers (represented by glass fiber). However, existing technologies have consistently failed to address the root cause of fiber-matrix interface failure. Numerous failure analyses indicate that over 90% of extreme-condition failures originate from preferential damage at the fiber-matrix interface. Current technologies, using conventional silane coupling agents such as KH-550 to pre-treat fibers, only achieve interfacial bonding through weak hydrogen bonds and van der Waals forces. At temperatures above 120°C or in high-humidity environments of 85°C / 85% RH, rapid hydrogen bond breakage leads to interfacial debonding. The resulting gaps become high-speed channels for electrolyte and moisture penetration, causing mechanical properties to decline by over 30% within 1000 hours. Simultaneously, concentrated electric fields at interfacial defects induce electric tree growth, leading to insulation breakdown. The CTI values ​​of existing products generally fail to meet the ≥1000V requirements of 1200V ultra-high voltage systems.

[0004] To address the aforementioned interface failure problem, existing technologies mainly employ two approaches: (1) Adding 10-20% fluoropolymer or inorganic filler to the matrix to improve its resistance to media, but this cannot repair or strengthen the fiber-matrix interface and will lead to a 20-30% decrease in the mechanical properties of the material, resulting in a significant increase in cost; (2) Pre-treating the fiber with conventional silane, which can improve the interfacial bonding and fiber storage, but will completely occupy the hydroxyl reaction sites on the fiber surface, making it impossible to achieve in-situ synergistic interfacial reaction and unable to provide resistance to media and insulation functions.

[0005] In summary, developing a high-temperature nylon composite material that possesses excellent interfacial bonding strength and long-term reliability under extreme conditions without significantly increasing costs or reducing mechanical properties has become a common technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] To address the aforementioned shortcomings, this application provides an enhanced high-temperature nylon composite material and its preparation method. This application utilizes in-situ interfacial synergistic modification to significantly improve the long-term reliability and insulation performance of the material under extreme operating conditions without significantly sacrificing mechanical and heat resistance properties.

[0007] In a first aspect, this application provides a reinforced high-temperature nylon composite material, which adopts the following technical solution:

[0008] A reinforced high-temperature nylon composite material, comprising the following components in parts by weight: 60-85 parts of ternary nylon matrix resin; 15-40 parts of inorganic reinforcing fiber; 2-8 parts of maleic anhydride-grafted SEBS (SEBS-g-MAH); 0.3-2.0 parts of 3-trifluoroacetoxypropyltrimethoxysilane; and 1-5 parts of functional additives.

[0009] The ternary nylon matrix resin is composed of PA66, PA6T / 6I copolymer, and PA9T; the weight ratio of PA66, PA6T / 6I copolymer, and PA9T is (3-5):(2-4):(3-5); the functional additives include the following components in parts by weight: antioxidant 0.2-1.5 parts, nucleating agent 0.1-1 parts, and lubricant 0.2-2 parts.

[0010] This application adopts the technical route of "in-situ reactive interface construction". Through the synergistic combination of 3-trifluoroacetoxypropyltrimethoxysilane and maleic anhydride grafted SEBS, a covalently bonded fluorine-containing interface layer is constructed in situ during melt blending, thereby solving the problem of fiber-matrix interface failure at the molecular level.

[0011] This application chooses 3-trifluoroacetoxypropyltrimethoxysilane instead of conventional silanes because conventional KH-550 can only form hydrogen bonds, while this fluorinated silane can undergo covalent reactions at both ends, simultaneously introducing fluorinated groups that are resistant to electrical tracking, achieving an integrated "coupling + functionalization". Secondly, this application chooses maleic anhydride-grafted SEBS instead of other toughening agents: SEBS-g-MAH has good compatibility with nylon, high reactivity, and superior heat resistance compared to general toughening agents such as POE-g-MAH, enabling simultaneous interfacial crosslinking and matrix toughening without excessively reducing the heat distortion temperature. Using silane alone cannot solve the problem of interfacial stress concentration, and using SEBS alone cannot improve the interfacial dielectric resistance and insulation performance. This application chooses a synergistic approach, achieving a "1+1>2" effect.

[0012] In this application, 3-trifluoroacetoxypropyltrimethoxysilane and maleic anhydride-grafted SEBS construct an integrated composite interface layer in the fiber-matrix interface region through multi-dimensional intermolecular interactions and covalent reactions, achieving synergistic performance enhancement, as detailed below:

[0013] (1) The trimethoxy end of 3-trifluoroacetoxypropyltrimethoxysilane can undergo dehydration condensation with the hydroxyl groups on the surface of inorganic fibers to form a stable Si-O covalent bond, which is firmly anchored to the fiber surface. Under the melt blending conditions of 280-315℃, its trifluoroacetoxy end can undergo amidation reaction with the terminal amino group of nylon molecules without additional catalyst, and directly connect the fiber and the matrix through covalent bonds.

[0014] Meanwhile, the anhydride groups of maleic anhydride grafted onto SEBS can also undergo ring-opening amidation reactions with the terminal amino groups of nylon, grafting onto the nylon molecular chains. Both act together on the terminal amino groups of nylon, forming an interpenetrating covalent cross-linked network in the nanoscale interfacial region: silane molecules anchor the fiber side, while SEBS-g-MAH is dispersed on the matrix side. The molecular chains of both are intertwined at the interface, upgrading the traditional "weak hydrogen bond interface" to a "continuous covalent cross-linked interface." The interfacial bonding strength is more than doubled compared to single silane modification, fundamentally solving the problem of interfacial debonding under high temperature and high humidity conditions.

[0015] (2) Single fluorinated silane modification can only improve the interfacial bonding strength, but the interfacial phase is rigid and the stress is easily concentrated at the interface when subjected to external impact, which leads to brittle fracture and the material impact strength is limited; single SEBS-g-MAH modification can only improve the matrix toughness, but the fiber-matrix interface bonding is weak and the external force cannot be effectively transferred to the high modulus inorganic fiber, thus limiting the reinforcement effect, and the interfacial gap will still become a medium penetration channel.

[0016] When the two are combined, the SEBS elastomer phase can be uniformly dispersed in the interface region. Under the action of external force, it dissipates impact energy by inducing crazes and generating shear bands, thus buffering the stress concentration at the interface. At the same time, the covalently bonded dense interface can efficiently transfer the stress borne by the matrix to the inorganic fiber, giving full play to the reinforcing effect of the fiber, and ultimately achieving "simultaneous improvement of tensile strength and impact strength", which solves the contradiction of "reinforcement inevitably reduces toughness, and toughening inevitably reduces strength" in traditional modification.

[0017] (3) A single SEBS-g-MAH does not significantly improve the dielectric barrier and insulation performance, and may even lead to a decrease in insulation performance due to the increase in the two-phase interface; a single fluorinated silane can only form a very thin fluorinated layer on the fiber surface, which cannot completely cover the permeation channels at the interface defects, resulting in insufficient long-term reliability.

[0018] When the two are combined, the low surface energy groups of fluorinated silane (CF) form the first barrier layer on the fiber surface, making it difficult for electrolyte and water vapor to wet and penetrate. The cross-linked interface phase completely eliminates the micro gaps between the fiber and the matrix, cutting off the rapid penetration path of the medium and significantly reducing the water absorption rate of the material. At the same time, the continuous and dense interface layer eliminates the electric field concentration points caused by interface defects. Combined with the excellent arc erosion resistance of the fluorinated groups, it greatly inhibits the growth of electrical trees, ultimately achieving a dual insulation improvement of "barrier + arc resistance". The material's CTI value and long-term insulation reliability both achieve an order of magnitude leap.

[0019] Optionally, the amount of maleic anhydride grafted with SEBS is 4-6 parts by weight.

[0020] Optionally, the grafting rate of the maleic anhydride-grafted SEBS is 1.0-2.0%.

[0021] In one specific embodiment, the maleic anhydride grafted SEBS is in the following weight proportions: 2 parts, 4 parts, 5 parts, 6 parts, and 8 parts.

[0022] In some specific embodiments, the maleic anhydride-grafted SEBS is present in parts by weight of 2-4 parts, 2-5 parts, 2-6 parts, 4-5 parts, 4-6 parts, 4-8 parts, 5-6 parts, 5-8 parts, or 6-8 parts.

[0023] Optionally, the 3-trifluoroacetoxypropyltrimethoxysilane is present in parts by weight of 0.8-1.5.

[0024] Optionally, the purity of the 3-trifluoroacetoxypropyltrimethoxysilane is ≥95%.

[0025] In one specific embodiment, the 3-trifluoroacetoxypropyltrimethoxysilane is present in parts by weight of 0.3 parts, 0.8 parts, 1.2 parts, 1.5 parts, and 2 parts.

[0026] In some specific embodiments, the 3-trifluoroacetoxypropyltrimethoxysilane is present in parts by weight of 0.3-0.8, 0.3-1.2, 0.3-1.5, 0.8-1.2, 0.8-1.5, 0.8-2, 1.2-1.5, 1.5-2, or 1.5-2.

[0027] Optionally, in the ternary nylon matrix resin, the weight ratio of PA66, PA6T / 6I copolymer, and PA9T is (3.5-4.5):(2.5-3.5):(3.5-4.5).

[0028] Optionally, the molar ratio of terephthaloyl hexamethylenediamine units to isophthaloyl hexamethylenediamine units in the PA6T / 6I copolymer is (7-8):(2-3).

[0029] Optionally, the terminal amino content of PA9T is 30-60 mol / t.

[0030] Optionally, the inorganic reinforcing fiber is 25-35 parts by weight.

[0031] Optionally, the inorganic reinforcing fiber is selected from any one or more of glass fiber, basalt fiber, and quartz fiber.

[0032] Optionally, the inorganic reinforcing fiber is chopped glass fiber with a length of 3-6 mm, a diameter of 10-15 μm, and a surface hydroxyl content of 0.5-2.0 mmol / g.

[0033] Optionally, the inorganic reinforcing fibers are not surface pretreated.

[0034] Optionally, the inorganic reinforcing fiber is pretreated with 0.1-0.5 wt% of a fluorinated epoxy silane or a silane coupling agent.

[0035] Optionally, the fluorinated epoxy silane is 3-trifluoroacetoxypropyltrimethoxysilane.

[0036] In one specific embodiment, the steps for pretreating chopped glass fibers with 3-trifluoroacetoxypropyltrimethoxysilane are as follows: immersing the fibers in a 0.1-0.5 wt% aqueous solution of 3-trifluoroacetoxypropyltrimethoxysilane for 10-15 seconds, drying at 90-105℃ for 20-40 minutes, and controlling the silane grafting rate at 0.3-0.5%.

[0037] Optionally, the silane coupling agent is KH-550 (γ-aminopropyltriethoxysilane).

[0038] In one specific embodiment, the steps for pretreating chopped glass fibers with KH-550 are as follows: Anhydrous ethanol and deionized water are mixed, and KH-550 at 0.5-1.5% of the weight of the chopped glass fibers is added. The mixture is stirred at room temperature for 20-30 minutes to fully hydrolyze the KH-550, resulting in a uniform modified solution. The chopped glass fibers are dried at 100-110℃ for 20-40 minutes, then immersed in the modified solution for 1-3 minutes, stirring to ensure uniform surface coating. After removing the chopped glass fibers and draining the solvent, they are dried at 70-90℃ for 20-40 minutes and cured at 100-110℃ for 80-100 minutes to obtain the pretreated chopped glass fibers.

[0039] Optionally, the antioxidant is any one or more of hindered phenolic antioxidants and phosphite antioxidants.

[0040] Optionally, the antioxidant is a mixture of hindered phenolic antioxidants and phosphite antioxidants prepared in a weight ratio of 1:(0.5-2).

[0041] Optionally, the nucleating agent is selected from any one or more of nano-silica and organomontmorillonite.

[0042] Optionally, the lubricant is selected from any one or more of calcium stearate and ethylene bis-stearamide.

[0043] Secondly, this application provides a method for preparing a reinforced high-temperature nylon composite material, using the following technical solution:

[0044] A method for preparing a reinforced high-temperature nylon composite material, the method comprising the following steps:

[0045] (1) Pretreatment: PA66, PA6T / 6I copolymer and PA9T are vacuum dried at 110-130℃, and the moisture content is controlled to be ≤0.05%; the inorganic reinforcing fiber is dried at 110-130℃ for 2-4 hours;

[0046] (2) Premixing: The dried PA66, PA6T / 6I copolymer, PA9T and maleic anhydride grafted SEBS are mixed with antioxidants, nucleating agents and lubricants in the required proportions for 5-10 minutes to obtain a premix.

[0047] (3) Melt blending and granulation: The premix, 3-trifluoroacetoxypropyltrimethoxysilane and dried inorganic reinforcing fiber are melt blended at 280-315℃; then cooled with water and granulated to obtain precursor particles;

[0048] (4) Injection molding: The precursor particles are dried at 110-130℃ for 3-5 hours and then injection molded to obtain high-temperature nylon composite material.

[0049] Optionally, a twin-screw extruder is used for melt granulation; the processing conditions of the twin-screw extruder are set as follows: Zone 1 280-290℃, Zone 2 290-300℃, Zone 3 300-310℃, Zone 4 305-315℃, Die head 305-315℃, and screw speed 300-500 rpm.

[0050] In summary, this application includes at least one of the following beneficial technical effects:

[0051] (1) This application uses two-component covalent cross-linking synergy to upgrade the interface bonding mode from weak hydrogen bonds to covalent bond network, and the bond energy is increased by more than 10 times; after soaking in electrolyte at 120℃ for 1000h, the tensile strength retention rate is increased from 72% of the prior art to more than 90%, which effectively solves the performance decay problem caused by electrolyte penetration and significantly enhances long-term reliability under extreme working conditions.

[0052] (2) The fluorine-containing composite interface layer formed in situ in this application has both dielectric barrier and arc erosion resistance functions. The material's tracking index (CTI) has been increased from 600V in the prior art to over 1100V, which fully meets the mandatory requirement of ≥1000V for insulation materials in 1200V ultra-high voltage systems. After 2000h of humid heat aging at 85℃ / 85%RH, the insulation resistance retention rate has been increased from 38% to 89%, and the long-term insulation stability has been greatly improved.

[0053] (3) This application improves the notched impact strength of the material by more than 25% through the synergistic effect of stress transfer and toughening, while the tensile strength increases instead of decreasing, thus solving the common problem of high-temperature nylon being "strong but not tough". The modification is mainly concentrated in the nanoscale interface region, with minimal impact on the heat resistance of the matrix resin. The heat distortion temperature decreases by only about 3%, thus retaining the core heat resistance advantage of high-temperature nylon.

[0054] (4) This application adopts the melt blending in-situ modification process, which does not require complex pre-surface treatment of the fiber. It can be directly implemented on the existing twin-screw extrusion production line, with good process compatibility and is suitable for large-scale industrial production. Detailed Implementation

[0055] Before describing the embodiments of this application in detail, it should be understood that the terminology used herein is for the purpose of describing a particular embodiment only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term pertains.

[0056] This application provides a reinforced high-temperature nylon composite material, comprising the following components in parts by weight: 60-85 parts of ternary nylon matrix resin; 15-40 parts of inorganic reinforcing fiber; 2-8 parts of maleic anhydride-grafted SEBS; 0.3-2.0 parts of 3-trifluoroacetoxypropyltrimethoxysilane; and 1-5 parts of functional additives. The ternary nylon matrix resin is composed of PA66, PA6T / 6I copolymer, and PA9T; the weight ratio of PA66, PA6T / 6I copolymer, and PA9T is (3-5):(2-4):(3-5). The functional additives include: 0.2-1.5 parts of antioxidant, 0.1-1 part of nucleating agent, and 0.2-2 parts of lubricant.

[0057] This application also provides a method for preparing the above-mentioned reinforced high-temperature nylon composite material, specifically including the following steps:

[0058] (1) Pretreatment: PA66, PA6T / 6I copolymer and PA9T are vacuum dried at 110-130℃, and the moisture content is controlled to be ≤0.05%; the inorganic reinforcing fiber is dried at 110-130℃ for 2-4 hours;

[0059] (2) Premixing: The dried PA66, PA6T / 6I copolymer, PA9T and maleic anhydride grafted SEBS are mixed with antioxidants, nucleating agents and lubricants in the required proportions for 5-10 minutes to obtain a premix.

[0060] (3) Melt blending and granulation: The premix, 3-trifluoroacetoxypropyltrimethoxysilane and dried inorganic reinforcing fiber are melt blended at 280-315℃; then cooled with water and granulated to obtain precursor particles;

[0061] (4) Injection molding: The precursor particles are dried at 110-130℃ for 3-5 hours and then injection molded to obtain the high-temperature nylon composite material. Melt granulation is performed using a twin-screw extruder; the processing conditions of the twin-screw extruder are set as follows: Zone 1 280-290℃, Zone 2 290-300℃, Zone 3 300-310℃, Zone 4 305-315℃, Die head 305-315℃, Screw speed 300-500 rpm.

[0062] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0063] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0064] The specific components used in the following examples are as follows: PA66 intrinsic viscosity 2.7 dL / g, terminal amine content 45 mol / t, industrial grade, commercially available; PA6T / 6I copolymer: 6T to 6I molar ratio 75:25, intrinsic viscosity 1.0 dL / g, industrial grade, commercially available; PA9T: intrinsic viscosity 0.9 dL / g, terminal amine content 40 mol / t, industrial grade, commercially available; chopped glass fiber: alkali-free E glass fiber, length 3 mm, diameter 10 μm. Surface hydroxyl content 1.2 mmol / g, untreated, commercially available; basalt fiber, quartz fiber: industrial grade, commercially available; maleic anhydride grafted SEBS: grafting rate 1.5%, melt flow rate 10g / 10min (230℃ / 5kg), industrial grade, commercially available; 3-trifluoroacetoxypropyltrimethoxysilane: purity ≥98%, industrial grade, commercially available; antioxidant 1010, antioxidant 168, nano silica, calcium stearate: all industrial grade, commercially available.

[0065] The present application will be further described in detail below with reference to the embodiments and test results.

[0066] Example 1

[0067] This embodiment provides a reinforced high-temperature nylon composite material. The specific components and dosages involved are shown in Table 1.

[0068] The preparation method of the above-mentioned composite material specifically includes the following steps:

[0069] (1) Pretreatment: PA66, PA6T / 6I copolymer and PA9T were vacuum dried at 120℃ for 5h, and the moisture content was controlled to be ≤0.05%. Short glass fibers were dried at 120℃ for 3h.

[0070] (2) Premixing: The dried PA66, PA6T / 6I copolymer, PA9T and maleic anhydride grafted SEBS, antioxidant 1010, antioxidant 168, nano silica and calcium stearate are added to a high-speed mixer according to the ratio and mixed for 8 minutes to obtain the premix.

[0071] (3) Melt blending and granulation: The premixed material is added from the main feed port of the twin-screw extruder, 3-trifluoroacetoxypropyltrimethoxysilane is added from the first side feed port, and chopped glass fiber is added from the second side feed port. The processing conditions of the twin-screw extruder are set as follows: Zone 1 285℃, Zone 2 295℃, Zone 3 305℃, Zone 4 310℃, and die head 310℃; the screw speed is 400 rpm. After melt blending, the material is cooled by water and granulated to obtain precursor particles.

[0072] (4) Injection molding: After drying the precursor particles at 120°C for 4 hours, injection molding is performed to obtain the high-temperature nylon composite material.

[0073] Examples 2-9

[0074] The above embodiments provide a reinforced high-temperature nylon composite material. The difference between these embodiments and Embodiment 1 lies in the amount of maleic anhydride-grafted SEBS and 3-trifluoroacetoxypropyltrimethoxysilane added, as shown in Table 1. All other operating steps remain the same as in Embodiment 1.

[0075] The differences between Examples 1-9 are as follows:

[0076] The difference between Examples 1-5 is that the amount of maleic anhydride grafted with SEBS is different.

[0077] The difference between Examples 3 and 6-9 is that the amount of 3-trifluoroacetoxypropyltrimethoxysilane added is different.

[0078] Examples 10-11

[0079] The above embodiments each provide a reinforced high-temperature nylon composite material. The difference between these embodiments and Embodiment 3 lies in the type of inorganic reinforcing fiber, as shown in Table 1. All other operating steps remain the same as in Embodiment 3.

[0080] Example 12

[0081] The above embodiments provide a reinforced high-temperature nylon composite material. The difference between this and Embodiment 3 is that it uses short-cut glass fibers pretreated with a low concentration of fluorinated epoxy silane (3-trifluoroacetoxypropyltrimethoxysilane), as shown in Table 1. All other operating steps are consistent with Embodiment 3.

[0082] The specific steps for pretreating chopped glass fibers with 3-trifluoroacetoxypropyltrimethoxysilane are as follows: immerse the fibers in a 0.3wt% aqueous solution of 3-trifluoroacetoxypropyltrimethoxysilane for 15 seconds, and dry them at 105℃ for 40 minutes to obtain pretreated chopped glass fibers. The silane grafting rate is controlled at 0.3-0.5%.

[0083] Example 13

[0084] The above embodiments provide a reinforced high-temperature nylon composite material. The difference between this and Embodiment 3 is that it uses short-cut glass fibers pretreated with a silane coupling agent (KH-550), as detailed in Table 1. All other operating steps remain the same as in Embodiment 3.

[0085] The specific steps for pretreating chopped glass fibers with KH-550 are as follows: Anhydrous ethanol and deionized water are mixed at a weight ratio of 7:3, and KH-550 at 1.0% of the weight of the chopped glass fibers is added. The mixture is stirred at room temperature for 25 minutes to allow KH-550 to be fully hydrolyzed, resulting in a uniform modified solution. The chopped glass fibers are dried at 105°C for 30 minutes, then immersed in the modified solution for 2 minutes, and stirred to ensure uniform surface coating. After removing the chopped glass fibers and draining the solvent, they are dried at 80°C for 30 minutes and cured at 105°C for 90 minutes to obtain the pretreated chopped glass fibers.

[0086] Comparative Example 1

[0087] The above comparative example provides a high-temperature nylon composite material. It differs from Example 3 in that maleic anhydride-grafted SEBS and 3-trifluoroacetoxypropyltrimethoxysilane were not added, and short-cut glass fibers pretreated with a silane coupling agent (KH-550) were used. The pretreatment method is the same as in Example 14. Specific details are shown in Table 1. All other operating steps are consistent with Example 3.

[0088] Comparative Example 2

[0089] The above comparative example provides a high-temperature nylon composite material. It differs from Example 3 in that maleic anhydride-grafted SEBS is not added; only 3-trifluoroacetoxypropyltrimethoxysilane is added, as shown in Table 1. All other operating steps are consistent with Example 3.

[0090] Comparative Example 3

[0091] The above comparative example provides a high-temperature nylon composite material. Its difference from Example 3 is that 3-trifluoroacetoxypropyltrimethoxysilane was not added; only maleic anhydride-grafted SEBS was added, as shown in Table 1. All other operating steps are consistent with Example 3.

[0092] Table 1. Components and proportions of the reinforced high-temperature nylon composite materials provided in the examples and comparative examples.

[0093]

[0094] Performance testing

[0095] The materials prepared in the above embodiments and comparative examples were subjected to the following tests.

[0096] (a) Detection methods

[0097] (1) Tensile strength

[0098] The testing was conducted in accordance with GB / T 1040.2-2022 standard. First, standard type 1A specimens were prepared by injection molding and tested using a universal testing machine at a speed of 5 mm / min and ambient temperature of room temperature. Five specimens were tested in each group, and the arithmetic mean was taken as the final result.

[0099] (2) Impact strength of simply supported beam with notch

[0100] The testing was conducted in accordance with GB / T 1043.1-2008 standard. First, a standard specimen with dimensions of 80×10×4mm was prepared by injection molding, and an A-type notch with a radius of 0.25mm was machined. The test was performed using a simply supported beam impact testing machine with a pendulum energy of 5J and ambient temperature of room temperature. Ten specimens were tested in each group, and the arithmetic mean was taken as the final result.

[0101] (3) Tensile strength retention rate after 1000h in electrolyte

[0102] The testing was conducted using methods commonly used in the new energy vehicle industry. The electrolyte formulation was a mixture of EC:DMC:EMC in a volume ratio of 1:1:1, with the addition of 1 mol / L LiPF6. The test sample was sealed and immersed in a polytetrafluoroethylene container and placed in a 120℃ oven for 1000 hours. After removing the sample, the surface electrolyte was wiped dry with anhydrous ethanol, and the sample was left at room temperature for 2 hours before the tensile strength was tested according to the above-described tensile strength test method.

[0103] The tensile strength retention rate is calculated as follows: Retention rate = Tensile strength after immersion / Initial tensile strength × 100%.

[0104] (4) Compared to the CTI (Cyclic Tracking Index)

[0105] The test was conducted in accordance with GB / T 4207-2022 standard. First, a standard plate sample with dimensions of 100×100×3mm was prepared. Before testing, the sample was conditioned for 24 hours at room temperature and relative humidity of (50±10)%. The test was conducted using a CTI tester, with solution A (ammonium chloride aqueous solution) as the test solution. The 50-drop method was used for testing, with 5 samples tested in each group. The lowest breakdown voltage was recorded as the final result.

[0106] (5) Insulation resistance retention rate after 2000h of damp heat aging

[0107] The tests were conducted in accordance with GB / T 31838.2-2019 and GB / T 2573-2008 standards. First, a standard flat plate sample with dimensions of 100×100×1mm was prepared and aged in a constant temperature and humidity chamber at 85℃ and 85% relative humidity for 2000 hours (meeting the requirements of GB / T 2573-2008 damp heat aging test). After removal, the sample was placed at room temperature for 24 hours, and its volume resistivity was measured using a high resistivity meter according to GB / T31838.2-2019 standard.

[0108] The formula for calculating insulation resistance retention rate is as follows: Retention rate = Volume resistivity after aging / Initial volume resistivity × 100%.

[0109] (6) Water absorption rate

[0110] The test was conducted in accordance with the GB / T 1034-2008 standard. First, a standard square plate sample with dimensions of 50×50×2mm was prepared by injection molding. The sample was then vacuum dried at 105℃ to constant weight, and the initial weight m0 was recorded. Subsequently, the sample was immersed in deionized water at 23℃ for 24 hours. After removing the sample, the surface moisture was quickly absorbed with filter paper, and the sample was immediately weighed and recorded as m1.

[0111] The formula for calculating water absorption rate is as follows: Water absorption rate = (m1-m0) / m0 × 100%.

[0112] (7) Heat distortion temperature

[0113] The testing was conducted in accordance with GB / T 1634.1-2019 standard. First, standard specimens with dimensions of 80×10×4mm were prepared by injection molding. The Vicat softening point tester was used for testing, with a test load of 1.82MPa and a heating rate of 120℃ / h. Five specimens were tested in each group, and the arithmetic mean was taken as the final result.

[0114] (8) Melt Flow Rate (MFR)

[0115] The test was conducted in accordance with GB / T 3682.1-2018 standard. A melt flow indexer was used for testing, with the test temperature set at 310℃ and the load at 5kg; the preheating time was 4min and the sample cutting interval was 10s; each group of tests was performed 3 times, and the arithmetic mean was taken as the final result.

[0116] (II) Test Results

[0117] The test results are shown in Table 2.

[0118] Table 2 Performance test results of the reinforced high-temperature nylon composite materials provided in the examples and comparative examples

[0119]

[0120] As shown in Table 2, by comparing the test results of Example 3 and Comparative Examples 1-3, it can be seen that Comparative Example 1 uses chopped glass fibers treated with KH-550 to prepare high-temperature nylon composite materials; Comparative Example 2 uses untreated chopped glass fibers and adds maleic anhydride-grafted SEBS to prepare high-temperature nylon composite materials; Comparative Example 3 uses untreated chopped glass fibers and adds 3-trifluoroacetoxypropyltrimethoxysilane to prepare high-temperature nylon composite materials; while Example 3 uses untreated chopped glass fibers and adds maleic anhydride-grafted SEBS and 3-trifluoroacetoxypropyltrimethoxysilane to prepare high-temperature nylon composite materials. The high-temperature nylon composite materials prepared by Example 3 have significantly improved strength retention rate, CTI value, notched impact strength of simply supported beam, and insulation resistance retention rate after 2000 hours of humid heat resistance in an electrolyte at 120°C for 1000 hours, and have no significant effect on water absorption rate, heat distortion temperature, tensile strength, and melt flow rate. Therefore, the high-temperature nylon composite material provided in this application can significantly improve the long-term reliability and insulation performance of the material under extreme working conditions without significantly sacrificing mechanical and heat resistance properties.

[0121] Comparative analysis of the test results from Examples 1-5 shows that the composite material made by combining maleic anhydride-grafted SEBS with 3-trifluoroacetoxypropyltrimethoxysilane, and adjusting the amount of maleic anhydride-grafted SEBS to 2-8 parts, exhibits excellent performance in terms of strength retention rate, CTI value, notched impact strength of simply supported beam, and insulation resistance retention rate after 2000 hours of damp heat resistance in an electrolyte solution at 120°C. Furthermore, controlling the amount of maleic anhydride-grafted SEBS to 4-6 parts further improves the strength retention rate, CTI value, notched impact strength of simply supported beam, and insulation resistance retention rate after 2000 hours of damp heat resistance in the high-temperature nylon composite material.

[0122] Comparing the test results of Examples 3 and 6-9, it is evident that the compounding of maleic anhydride-grafted SEBS with 3-trifluoroacetoxypropyltrimethoxysilane, with the amount of 3-trifluoroacetoxypropyltrimethoxysilane controlled at 0.3-2 parts, yielded a reinforced high-temperature nylon composite material exhibiting excellent performance in terms of strength retention rate, CTI value, notched impact strength of a simply supported beam, and insulation resistance retention rate after 2000 hours of damp heat treatment in an electrolyte solution at 120°C. Furthermore, controlling the amount of 3-trifluoroacetoxypropyltrimethoxysilane added at 0.8-1.5 parts further improves the strength retention rate, CTI value, notched impact strength of a simply supported beam, and insulation resistance retention rate after 2000 hours of damp heat treatment in the high-temperature nylon composite material.

[0123] By comparing the test results of Example 3 with those of Examples 10-11, it can be seen that when basalt fiber or quartz fiber is used, the reinforced high-temperature nylon composite material also has high strength retention rate, CTI value, notched impact strength of simply supported beam, and insulation resistance retention rate after 2000 hours of damp heat resistance in electrolyte at 120℃.

[0124] Comparing the test results of Examples 3 and 12-13, it can be seen that when chopped glass fibers are pretreated with 3-trifluoroacetoxypropyltrimethoxysilane (Example 12), the resulting high-temperature nylon composite material exhibits higher strength retention rate at 120°C for 1000 hours in an electrolyte solution, higher CTI value, higher notched impact strength of a simply supported beam, and higher insulation resistance retention rate after 2000 hours of damp heat. However, when chopped glass fibers are pretreated with KH-550 (Example 13), the premature occupation of surface sites by KH-550 affects the subsequent crosslinking reaction, which to some extent affects the various properties of the resulting high-temperature nylon composite material, leading to a decrease in the strength retention rate at 120°C for 1000 hours in an electrolyte solution, lower CTI value, lower notched impact strength of a simply supported beam, and lower insulation resistance retention rate after 2000 hours of damp heat.

[0125] In summary, the high-temperature nylon composite material provided in this application significantly improves the long-term reliability and insulation performance under extreme working conditions without significantly sacrificing mechanical and heat resistance properties. It has excellent overall performance and potential application value in aerospace, military equipment, chemical equipment, electronic devices, new energy materials and other fields.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A reinforced high-temperature nylon composite material, characterized in that, The high-temperature nylon composite material comprises the following components in parts by weight: 60-85 parts of ternary nylon matrix resin; 15-40 parts of inorganic reinforcing fiber; 2-8 parts of maleic anhydride-grafted SEBS; 0.3-2.0 parts of 3-trifluoroacetoxypropyltrimethoxysilane; and 1-5 parts of functional additives. The ternary nylon matrix resin is composed of PA66, PA6T / 6I copolymer and PA9T, and the weight ratio of PA66, PA6T / 6I copolymer and PA9T is (3-5):(2-4):(3-5). The functional additives comprise the following components in parts by weight: 0.2-1.5 parts antioxidant, 0.1-1 part nucleating agent, and 0.2-2 parts lubricant.

2. The reinforced high-temperature nylon composite material according to claim 1, characterized in that, The amount of maleic anhydride grafted onto SEBS is 4-6 parts by weight.

3. The reinforced high-temperature nylon composite material according to claim 1, characterized in that, The 3-trifluoroacetoxypropyltrimethoxysilane is present in parts by weight of 0.8-1.

5.

4. The reinforced high-temperature nylon composite material according to claim 1, characterized in that, The weight ratio of PA66, PA6T / 6I copolymer, and PA9T is (3.5-4.5):(2.5-3.5):(3.5-4.5). Optionally, the molar ratio of terephthaloyl hexamethylenediamine units to isophthaloyl hexamethylenediamine units in the PA6T / 6I copolymer is (7-8):(2-3). Optionally, the terminal amino group content of PA9T is 30-60 mol / t; Optionally, the inorganic reinforcing fiber is 25-35 parts by weight.

5. The reinforced high-temperature nylon composite material according to claim 1, characterized in that, The inorganic reinforcing fiber is selected from any one or more of glass fiber, basalt fiber, and quartz fiber; Optionally, the inorganic reinforcing fiber is chopped glass fiber with a length of 3-6 mm, a diameter of 10-15 μm, and a surface hydroxyl content of 0.5-2.0 mmol / g.

6. The reinforced high-temperature nylon composite material according to claim 1, characterized in that, The inorganic reinforcing fibers were not subjected to surface pretreatment. Alternatively, the inorganic reinforcing fibers may be pretreated with 0.1-0.5 wt% of a fluorinated epoxy silane or a silane coupling agent.

7. The reinforced high-temperature nylon composite material according to claim 1, characterized in that, The antioxidant is any one or more of hindered phenolic antioxidants and phosphite antioxidants; Optionally, the antioxidant is a mixture of hindered phenolic antioxidants and phosphite antioxidants prepared in a weight ratio of 1:(0.5-2).

8. The reinforced high-temperature nylon composite material according to claim 1, characterized in that, The nucleating agent is selected from any one or more of nano-silica and organomontmorillonite; Optionally, the lubricant is selected from any one or more of calcium stearate and ethylene bis-stearamide.

9. A method for preparing a reinforced high-temperature nylon composite material according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: (1) Pretreatment: PA66, PA6T / 6I copolymer and PA9T are vacuum dried at 110-130℃, and the moisture content is controlled to be ≤0.05%; the inorganic reinforcing fiber is dried at 110-130℃ for 2-4 hours; (2) Premixing: The dried PA66, PA6T / 6I copolymer, PA9T and maleic anhydride grafted SEBS are mixed with antioxidants, nucleating agents and lubricants in the required proportions for 5-10 minutes to obtain a premix. (3) Melt blending and granulation: The premix, 3-trifluoroacetoxypropyltrimethoxysilane and dried inorganic reinforcing fiber are melt blended at 280-315℃; then cooled with water and granulated to obtain precursor particles; (4) Injection molding: The precursor particles are dried at 110-130℃ for 3-5 hours and then injection molded to obtain high-temperature nylon composite material.

10. The preparation method according to claim 9, characterized in that, Melt granulation is performed using a twin-screw extruder; the processing conditions of the twin-screw extruder are set as follows: Zone 1 280-290℃, Zone 2 290-300℃, Zone 3 300-310℃, Zone 4 305-315℃, Die head 305-315℃, Screw speed 300-500rpm, Residence time 1-2min.

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