High modulus high temperature resistant fiber pultruded insulated core and method of making

Abstract

This invention discloses a high-modulus, high-temperature resistant fiber pultruded insulating core and its preparation method, relating to the field of insulating core technology. The raw materials for its preparation include the following components by weight: 75-85 parts of a mixture of high-performance glass fiber and aramid fiber, and 15-25 parts of epoxy resin adhesive. The epoxy resin adhesive includes the following components by weight: 6.5-14.5 parts of epoxy resin, 6.5-14 parts of curing agent, and 0.2-1 parts of accelerator. This invention utilizes bisphenol A epoxy resin, difunctional naphthyl epoxy resin, and trifunctional aniline epoxy resin, significantly improving the overall performance of the insulating core. The use of methyltetrahydrophthalic anhydride curing agent and accelerator in combination allows the anhydride curing agent to rapidly cure the epoxy resin within the curing temperature range. α-nano alumina significantly improves the rigidity and hardness of the epoxy resin matrix, increases the elastic modulus, and enables the preparation of large-diameter cores, improving the core's thermal shock resistance.

Description

Technical Field

[0001] This invention relates to the field of insulating core technology, and in particular to a high-modulus, high-temperature resistant fiber pultruded insulating core and its preparation method. Background Technology

[0002] With the development of the Global Energy Internet, ultra-high voltage (UHV) transmission (UHV ≥ 1000kV AC / ±800kV DC) has become a core technology for large-capacity, long-distance power transmission. UHV post insulators, as key support and insulation components, withstand extremely harsh mechanical loads during operation, including enormous conductor tension, strong wind loads, equipment self-weight, and long-term continuous mechanical stress. The performance of their core load-bearing component, the insulating core rod, is crucial to the safety and reliability of the equipment. Traditional porcelain or glass insulators have inherent defects such as large weight, high brittleness, and limited anti-flashover capabilities, making it difficult to meet the ever-increasing safety and economic requirements of UHV systems.

[0003] Fiber-reinforced resin matrix composites (FRPs) have become the preferred material for next-generation insulating core rods due to their excellent specific strength, specific modulus, corrosion resistance, and designability. The epoxy resin matrix provides excellent electrical insulation, weather resistance, and interfacial adhesion, while reinforcing phases such as glass fibers impart axial mechanical properties. However, high-modulus FRP insulating core rods in existing technologies still face significant challenges: Modulus improvement bottlenecks and balancing overall performance: The modulus of conventional glass fiber reinforced epoxy core rods (typically in the range of 30–40 GPa) is insufficient to meet the higher modulus requirements (generally ≥50 GPa) for ultra-high voltage (UHV) power transmission lines. Simply increasing fiber content or modulus often leads to a decrease in toughness, impact resistance, or processability. Achieving effective synergy between high modulus and other key properties (such as strength, heat resistance, and weather resistance) is the core challenge. Interface and long-term reliability risks: The long-term service performance of the core rod is highly dependent on the bond strength and stability of the fiber-resin interface. Existing interface treatment technologies are insufficient to completely suppress the risk of interface degradation or delamination failure under complex alternating stress and environmental factors (such as temperature and humidity) in high-modulus, high-rigidity systems, affecting long-term reliability. High-temperature resistance and thermal stability are also crucial: ultra-high voltage equipment operation may be accompanied by temperature rise. Conventional epoxy resin systems have relatively limited glass transition temperatures and heat distortion temperatures; when high-modulus mandrels are subjected to higher stresses, their high-temperature stiffness and dimensional stability may be insufficient, and their thermal shock resistance needs improvement. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a high-modulus high-temperature resistant fiber pultruded insulating core and its preparation method, which significantly improves the axial modulus of the mandrel while taking into account high bending strength, excellent high temperature resistance, long-term environmental stability, strong interfacial bonding and good thermal shock resistance, so as to meet the stringent requirements of ultra-high voltage post insulators for extreme mechanical properties and long-term reliability.

[0005] The technical solution adopted to solve the above-mentioned technical problems is: a high-modulus, high-temperature resistant fiber pultruded insulating core, the raw materials of which include the following components by weight: 75-85 parts of a mixture of high-performance glass fiber and aramid fiber, wherein the mass ratio of high-performance glass fiber to aramid fiber is (1-10):1; and 15-25 parts of epoxy resin adhesive; wherein the epoxy resin adhesive includes the following components by weight: 6.5-14.5 parts of epoxy resin; and 6.5 parts of curing agent. ~14 parts; accelerator 0.2~1 parts, the mass ratio of epoxy resin to curing agent is 100:(90~110); the epoxy resin includes the following components by weight: 4.5~9 parts of bisphenol A epoxy resin; 1~3 parts of difunctional naphthyl epoxy resin; 1~2.5 parts of trifunctional aniline epoxy resin; wherein the mass ratio of bisphenol A epoxy resin, difunctional naphthyl epoxy resin and trifunctional aniline epoxy resin is 12:(2~5):(3~6).

[0006] Furthermore, the difunctional naphthyl epoxy resin is 2,2'-[1,6-naphthylbis(oxomethylene)]diepoxyethylene; the trifunctional aniline epoxy resin is a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin.

[0007] Furthermore, the epoxy equivalent of the bisphenol A epoxy resin is 185-208.

[0008] Furthermore, the curing agent is methyltetrahydrophthalic anhydride.

[0009] Furthermore, the accelerator comprises a mixture of tris(dimethylaminomethyl)phenol and 2-ethyl-4-methylimidazole, wherein the mass ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is (1-3):1, and the accelerator accounts for 0.5%-2% of the total amount of epoxy resin.

[0010] Furthermore, the epoxy resin adhesive also includes 0.5 to 1.5 parts of functional filler, which is α-nano alumina treated with a silane coupling agent. The silane coupling agent is 3-aminopropyltriethoxysilane or 3-(2,3-epoxypropoxy)propyltrimethoxysilane. The particle size of the α-nano alumina is 10 to 100 nm, and the α-nano alumina accounts for 3% to 5% of the total amount of epoxy resin adhesive.

[0011] Furthermore, the epoxy resin adhesive also includes ultraviolet absorbers and light stabilizers, which account for 0.2% to 1% of the total adhesive content of the epoxy resin adhesive, and the mass ratio of ultraviolet absorbers to light stabilizers is 1:1.

[0012] A method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core includes the following steps:

[0013] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in an oven at 120℃ for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 2-4 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 10-30 minutes to remove the supernatant. The precipitate was washed with ethanol 2-3 times to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 4-8 hours to obtain the treated α-nano alumina.

[0014] S2, Prepare the resin adhesive: Take 75-85 parts of a mixture of high-performance glass fiber and aramid fiber, 4.5-9 parts of bisphenol A epoxy resin, add 1-3 parts of 2,2'-[1,6-naphthylbis(oxymethylene)]diepoxide, and 1-2.5 parts of a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin, stir for 10-20 minutes, add 0.5-1 parts of α-nano alumina treated in step S1, stir evenly, and ultrasonically disperse at 60°C for 30-60 minutes;

[0015] After cooling, add 6.5–14 parts of methyltetrahydrophthalic anhydride, add 0.5%–2% of the total mass of the resin adhesive as an accelerator, which is a blend of tris(dimethylaminomethyl)phenol and 2-ethyl-4-methylimidazole, with a blending ratio of (1–3):1. Add 0.2%–1% of the total mass of the epoxy resin adhesive as a UV absorber and a light stabilizer, with a mass ratio of 1:1. Stir under vacuum for 30–60 minutes and let stand for later use.

[0016] S3, Fiber treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. The yarn guides ensure that the fibers are evenly distributed and arranged in parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 80-100°C for 30-90 seconds.

[0017] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank. The fiber bundle after step S3 enters the impregnation tank, so that the fiber is completely impregnated and the resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0018] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0019] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold under the traction of the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: entrance zone 80-100°C, gel / curing zone 160-180°C, and post-curing zone 170-175°C. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0020] S7, Continuous traction and cutting: After the prepreg bundle is cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and continuously pull it out of the core mold. After the continuously cured and pulled core reaches the predetermined length, it is cut into finished products of the required length.

[0021] Furthermore, the silane coupling agent is KH550 coupling agent or KH560 coupling agent; the preparation method of the KH550 coupling agent hydrolysis solution is as follows: deionized water and ethanol are mixed and stirred evenly, wherein the mass ratio of deionized water to ethanol is 8:72, KH550 silane coupling agent is added, and stirred until completely dissolved to prepare a 20% KH550 hydrolysis solution, which is then aged at 60°C in the dark for 30-60 minutes;

[0022] The preparation method of the KH560 coupling agent hydrolysis solution is as follows: deionized water and ethanol are mixed and stirred evenly, wherein the mass ratio of deionized water to ethanol is 8:72. KH560 silane coupling agent is added to prepare a 20% KH560 hydrolysis solution. The pH of the solution is adjusted to 4-5 with dilute acetic acid and formic acid. The solution is stirred evenly and aged at 60°C in the dark for 30-60 minutes.

[0023] The beneficial effects of the present invention are as follows: (1) The present invention uses bisphenol A epoxy resin, difunctional naphthyl epoxy resin, and trifunctional aniline epoxy resin. The three epoxy resins complement each other, greatly improving the comprehensive performance of the insulating core. The use of methyltetrahydrophthalic anhydride curing agent and the combination of tris(dimethylaminomethyl)phenol and 2-ethyl-4-methylimidazol as accelerators can enable the anhydride curing agent to quickly cure the epoxy resin within the curing temperature range, making it easier to achieve rapid molding in the pultrusion process and improve production efficiency.

[0024] (2) The present invention adds α nano aluminum oxide, which greatly improves the rigidity of the epoxy resin body, increases the hardness of the epoxy resin body, improves the elastic modulus, and increases the thermal conductivity of the core, thereby making the core heat-uniform and enabling the preparation of large-diameter cores and improving the thermal shock resistance of the core.

[0025] (3) The present invention adds ultraviolet absorbers and light stabilizers to maintain the color stability of epoxy products, significantly improve the anti-aging performance of epoxy resin in outdoor environment, avoid the embrittlement and cracking of insulating core, and solve the problem of insufficient UV resistance of naphthalene epoxy resin.

[0026] (4) The present invention adopts the pultrusion process, which can realize highly automated production. By continuously traction fiber impregnating resin and curing, the efficiency is greatly improved, the product quality is stable, the dimensional accuracy is high, and no post-processing is required, saving labor and time. The fiber volume content is high, and the fiber mass content can be as high as 82% or more. By adjusting the fiber arrangement, specific mechanical requirements can be met. The raw material utilization rate is over 95%. There is no waste material in the production process, the raw material utilization rate is high, and the energy consumption is low. Attached Figure Description

[0027] Figure 1 This is a flowchart of an embodiment of the preparation method of the high-modulus, high-temperature resistant fiber pultruded insulating core of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] This embodiment provides a high-modulus, high-temperature resistant fiber pultruded insulating core, the raw materials of which include the following components by weight: 75-85 parts of a mixture of high-performance glass fiber and aramid fiber, wherein the mass ratio of high-performance glass fiber to aramid fiber is (1-10):1, and 15-25 parts of epoxy resin.

[0030] High-performance glass fiber has a tensile strength of 4000 MPa and an elastic modulus higher than 87 GPa, and can withstand high temperatures up to 650℃, making it the high-modulus core of the insulation material. Aramid fiber has a tensile strength greater than 2900 MPa and an elastic modulus higher than 80 GPa. Unlike high-performance glass fiber, aramid fiber maintains high modulus while also possessing high toughness. When used in combination with high-performance glass fiber, it significantly improves the fiber's toughness.

[0031] The epoxy resin adhesive comprises the following components by weight: 6.5–14.5 parts epoxy resin, 6.5–14 parts curing agent, 0.2–1 part accelerator, with a mass ratio of epoxy resin to curing agent of 100:(90–110), 0.5–1.5 parts functional filler, wherein the functional filler is α-nano alumina treated with a silane coupling agent, the silane coupling agent being 3-aminopropyltriethoxysilane or 3-(2,3-epoxypropoxy)propyltrimethoxysilane, the particle size of the α-nano alumina being 10–100 nm, and the α-nano alumina comprising 3%–5% of the total epoxy resin adhesive. UV absorber and light stabilizer, comprising 0.2%–1% of the total epoxy resin adhesive content, with a mass ratio of UV absorber to light stabilizer of 1:1.

[0032] The epoxy resin comprises the following components by weight: 4.5 to 9 parts of bisphenol A epoxy resin, with an epoxy equivalent of 185 to 208 for the bisphenol A epoxy resin; 1 to 3 parts of difunctional naphthyl epoxy resin; and 1 to 2.5 parts of trifunctional aniline epoxy resin. The mass ratio of the bisphenol A epoxy resin, the difunctional naphthyl epoxy resin, and the trifunctional aniline epoxy resin is 12:(2 to 5):(3 to 6). The difunctional naphthyl epoxy resin is 2,2'-[1,6-naphthylbis(oxomethylene)]diepoxyethylene, and the trifunctional aniline epoxy resin is a mixture of P-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline epoxy resin.

[0033] Bisphenol A type epoxy resins, with their high reactivity, excellent adhesion, and balanced mechanical and electrical properties, have become the core matrix resins in composite materials, electronic packaging, coatings, and other fields. The combination of rigid benzene rings and flexible ether bonds in its molecular structure endows the material with a balance of high strength and moderate toughness, as shown in Formula 1.

[0034] Structural Formula 1

[0035]

[0036] Where n = 0, 1.

[0037] Difunctional Naphthalene-based epoxy resin: 2,2'-[1,6-naphthylbis(oxomethylene)]diepoxide (EBA-65) belongs to the naphthalene-type epoxy resin category. It is difunctional with an epoxy value of 0.65–0.73. The naphthalene ring possesses high planar symmetry, giving the epoxy resin higher rigidity, which in turn results in higher flexural strength, higher flexural modulus, and a higher glass transition temperature (Tg can reach over 240℃ when DDS is used as a curing agent). Compared to other high-temperature resistant resins, this epoxy resin has a low water absorption rate (room temperature saturated water absorption rate <1.2%, Tg retention rate >90% after 48h of humid heat at 85℃ / 85%RH). Its structural formula is shown in Formula 2.

[0038] Structural Formula 2

[0039]

[0040] Trifunctional aniline epoxy resin: P-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline (AFG-90MH) is a trifunctional epoxy resin. At room temperature, it is a reddish-brown liquid with an epoxy value exceeding 0.9. It can form a highly cross-linked, dense network, giving the cured product excellent mechanical strength and chemical resistance. Its viscosity at room temperature is only 2000–3000 mPa·s, only 1 / 10 to 1 / 5 that of ordinary bisphenol A epoxy resin. When cured using DDS curing agent, the flexural strength of the pure epoxy resin cured product can reach 190 MPa, and the flexural modulus 4 GPa, far exceeding the flexural strength and flexural modulus of ordinary bisphenol A cured products (the flexural strength of DDS cured products of ordinary bisphenol A epoxy resin is typically <100 MPa, and the flexural modulus is <3 GPa). AFG-90MH epoxy resin has 10 times the reactivity of bisphenol A type epoxy resin, resulting in higher bonding strength after curing and faster reaction at high temperatures. When copolymerized with other two resins, it is easier to achieve rapid prototyping in pultrusion processes, thereby improving production efficiency. Its structural formula is shown in Formula 3.

[0041] Structural Formula 3

[0042] ​​

[0043] Curing agent: Methyltetrahydrophthalic anhydride, also known as methyltetrahydrophthalic anhydride (MeTHPA), is an acid anhydride curing agent. It is a pale yellow, low-viscosity liquid at room temperature. It has the characteristics of low melting point, low toxicity, and low volatility. It is easy to use and has high reactivity and good miscibility with epoxy resin. Epoxy resin cured with this curing agent has excellent electrical insulation and mechanical properties. In particular, it has a long service life. Under the catalytic action of the accelerator at the curing temperature, it can be cured quickly, making it very suitable for pultrusion production processes. Its structural formula is shown in Formula 4.

[0044] Structural Formula 4

[0045]

[0046] Accelerator: Tris(dimethylaminomethyl)phenol (DMP-30) is a tertiary amine accelerator. It is a colorless or pale yellow transparent liquid at room temperature. Its molecular structure has one phenol ring connected to three tertiary amine methyl groups. It has a high catalytic efficiency and can effectively accelerate the curing of epoxy resin and curing agent.

[0047] Accelerator: 2-Ethyl-4-methylimidazolium is an imidazolium accelerator that is a pale yellow crystal at room temperature. The imidazolium ring contains one secondary amino group and one tertiary amino group, and its catalytic efficiency is also very high.

[0048] The two accelerators, when used in combination, enable the anhydride curing agent to rapidly cure epoxy resin within the curing temperature range. The molecular structure of the accelerator tris(dimethylaminomethyl)phenol is shown in Formula 5, and the structural formula of the accelerator 2-ethyl-4-methylimidazol is shown in Formula 6.

[0049] Structural Formula 5

[0050]

[0051] Structural Formula 6

[0052]

[0053] The functional filler selected is α-alumina nanoparticles treated with silane coupling agents. α-alumina (commonly known as corundum) is the most stable phase among all alumina. α-alumina belongs to the trigonal crystal system, with oxygen ions arranged in an approximately close-packed hexagonal structure, while aluminum atoms fill the octahedral voids. Due to the synergistic effect of the close-packed oxygen ions and the partial filling of aluminum ions, α-alumina possesses extremely high melting point (2015℃), hardness (Mohs hardness 8–8.8), and chemical stability. α-alumina nanoparticles participate in the epoxy resin curing network through coupling agents. Through the large interfaces formed in the epoxy resin and the resulting strong interfacial interactions (mainly hydrogen bonds), they firmly bind the surrounding polymer segments, increasing the effective crosslinking density and forming restricted movement regions. Simultaneously, its own rigidity also constrains segment movement, thereby significantly improving the elastic modulus of the epoxy resin. The addition of α-nano alumina can significantly increase the thermal conductivity of epoxy resin. Improved thermal conductivity of the core can reduce cracking caused by thermal shock. During pultrusion molding, the heat from the core mold can be transferred to the core center more quickly, reducing uneven heating and allowing the epoxy resin in the core center to cure more fully. This enhances the adhesion between the resin and the fiber, thereby increasing the elastic modulus of the insulating core rod. At the same time, α-alumina can quickly transfer the heat generated in the core center to the outside during the rapid curing of the resin, preventing heat accumulation and increasing the thermal shock resistance of the insulating core.

[0054] The silane coupling agent is KH550, with the structural formula shown in Formula 7, and the silane coupling agent is KH560, with the structural formula shown in Formula 8.

[0055] Structural Formula 7

[0056]

[0057] Structural Formula 8

[0058]

[0059] The preparation method of KH550 coupling agent hydrolysis solution is as follows: mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH550 silane coupling agent and stir until completely dissolved to prepare a 20% KH550 hydrolysis solution. Aging at 60℃ in the dark for 30 to 60 minutes.

[0060] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4-5 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 30-60 minutes.

[0061] Silane coupling agents play a crucial bridging role in glass fiber reinforced epoxy resin composites. Their core mechanism lies in simultaneously reacting or strongly interacting with the glass fiber surface and the epoxy resin matrix to form a strong and durable covalent bond between them. This interfacial modification is crucial to the flexural strength and flexural modulus of the insulating core.

[0062] UV absorbers reduce the auto-oxidation reaction induced by UV radiation, while light stabilizers prevent yellowing caused by free radicals, working together to maintain the color stability of epoxy products. The naphthyl epoxy resin of this invention is itself sensitive to UV radiation; while it offers high modulus, it may suffer from insufficient weather resistance. The UV absorbers and light stabilizers precisely compensate for this deficiency in UV aging resistance. The combined use of these two agents significantly improves the anti-aging performance of epoxy resin in outdoor environments, preventing problems such as embrittlement and cracking.

[0063] Example 1

[0064] This embodiment describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps: Figure 1 As shown.

[0065] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0066] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH560 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0067] In this embodiment, the surface of α-nano alumina is modified by treating it with a silane coupling agent to enhance its compatibility and bonding with the subsequent resin adhesive, eliminate the physically adsorbed water on the surface of α-nano alumina, and avoid the generation of bubbles in the subsequent preparation process.

[0068] S2, Prepare the resin adhesive: Take 82 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of 2:1 between the high-performance glass fiber and aramid fiber, 5.5 parts of bisphenol A epoxy resin, add 1.8 parts of 2,2'-[1,6-naphthylbis(oxymethylene)]diepoxide, and 1.2 parts of a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin, stir for 10-20 minutes, add 0.9 parts of α-nano alumina treated in step S1, stir evenly, and ultrasonically disperse at 60°C for 60 minutes.

[0069] After cooling, add 8.2 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole (the blending ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is 1:1), add 0.5% of the total amount of epoxy resin adhesive and 0.5% of the total amount of resin adhesive light stabilizer (the mass ratio of UV absorber to light stabilizer is 1:1), vacuum stir for 60 minutes, and let stand for later use.

[0070] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0071] Ensure that the coupling agent on the fiber surface is fully cured and all moisture is removed, while avoiding damage to the fiber due to high temperature. After drying, there should be no obvious liquid residue on the fiber surface, and it should feel dry and soft to the touch, without any lumps.

[0072] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0073] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0074] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0075] S7, Continuous traction and cutting: After the prepreg bundle is cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and continuously pull it out of the core mold. After the continuously cured and pulled core reaches the predetermined length, it is cut into finished products of the required length.

[0076] Example 2

[0077] This embodiment describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0078] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0079] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0080] S2, Prepare the resin adhesive: Take 80 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of 2:1 between the high-performance glass fiber and aramid fiber, 6 parts of bisphenol A epoxy resin, add 2 parts of 2,2'-[1,6-naphthylbis(oxymethylene)]diepoxide, and 1.5 parts of a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin. Stir for 20 minutes, add 1 part of α-nano alumina treated in step S1 and stir evenly. Ultrasonically disperse at 60°C for 60 minutes.

[0081] After cooling, add 9.1 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole (the blending ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is 1:1), add 0.5% of the total amount of epoxy resin adhesive and 0.5% of the total amount of resin adhesive light stabilizer (the mass ratio of UV absorber to light stabilizer is 1:1), vacuum stir for 60 minutes, and let stand for later use.

[0082] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0083] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0084] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0085] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0086] S7, Continuous traction and cutting: After the prepreg bundle is cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and continuously pull it out of the core mold. After the continuously cured and pulled core reaches the predetermined length, it is cut into finished products of the required length.

[0087] Example 3

[0088] This embodiment describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0089] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0090] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0091] S2, Prepare the resin adhesive: Take 78 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of 2:1 between the high-performance glass fiber and aramid fiber, 7 parts of bisphenol A epoxy resin, add 2 parts of 2,2'-[1,6-naphthylbis(oxymethylene)]diepoxide, and 1.5 parts of a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin. Stir for 20 minutes, add 1.1 parts of α-nano alumina treated in step S1 and stir evenly. Ultrasonically disperse at 60°C for 60 minutes.

[0092] After cooling, add 10 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole, with a blending ratio of (1-3):1. Add 0.5% of the total amount of epoxy resin adhesive as UV absorber and 0.5% of the total amount of epoxy resin adhesive as light stabilizer, with a mass ratio of UV absorber to light stabilizer of 1:1. Stir under vacuum for 60 minutes and let stand for later use.

[0093] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0094] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0095] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0096] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0097] S7, Continuous traction and cutting: After the prepreg bundle is cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and continuously pull it out of the core mold. After the continuously cured and pulled core reaches the predetermined length, it is cut into finished products of the required length.

[0098] Example 4

[0099] This embodiment describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0100] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0101] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0102] S2, Prepare the resin adhesive: Take 76 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of 2:1 between the high-performance glass fiber and aramid fiber, 8 parts of bisphenol A epoxy resin, add 2 parts of 2,2'-[1,6-naphthylbis(oxymethylene)]diepoxide, and 1.4 parts of a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin. Stir for 20 minutes, add 1.2 parts of α-nano alumina treated in step S1 and stir evenly. Ultrasonically disperse at 60°C for 60 minutes.

[0103] After cooling, add 11 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole, with a blending ratio of (1-3):1. Add 0.5% of the total amount of epoxy resin adhesive as UV absorber and 0.5% of the total amount of epoxy resin adhesive as light stabilizer, with a mass ratio of UV absorber to light stabilizer of 1:1. Stir under vacuum for 60 minutes and let stand for later use.

[0104] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0105] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0106] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0107] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0108] S7, Continuous traction and cutting: After the prepreg bundle is cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and continuously pull it out of the core mold. After the continuously cured and pulled core reaches the predetermined length, it is cut into finished products of the required length.

[0109] Comparative Example 1

[0110] This comparative example describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0111] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0112] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0113] S2, Prepare the resin adhesive: Take 80 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of high-performance glass fiber to aramid fiber of 2:1, 8 parts of bisphenol A epoxy resin and 2 parts of P-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline (AFG-90MH), stir for 20 minutes, add 1 part of α-nano alumina treated in step S1 and stir evenly, and ultrasonically disperse at 60℃ for 60 minutes.

[0114] After cooling, add 9 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole (the blending ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is 1:1), add 0.5% of the total amount of epoxy resin adhesive and 0.5% of the total amount of resin adhesive light stabilizer (the mass ratio of UV absorber to light stabilizer is 1:1), vacuum stir for 60 minutes, and let stand for later use.

[0115] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0116] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0117] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0118] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0119] S7, Continuous traction: After the prepreg bundle has been cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and pull it out of the core mold continuously.

[0120] S8, Cutting: After the fully cured and pulled continuous core reaches the predetermined length, it is cut into finished products of the required length.

[0121] Comparative Example 2

[0122] This comparative example describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0123] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0124] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0125] S2, Prepare the resin adhesive: Take 80 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of 2:1 between the high-performance glass fiber and aramid fiber, 8 parts of bisphenol A epoxy resin and 2 parts of 2,2'-[1,6-naphthylbis(oxomethylene)]diepoxide (EBA-65), stir for 20 minutes, add 1 part of α-nano alumina treated in step S1 and stir evenly, then ultrasonically disperse at 60°C for 60 minutes.

[0126] After cooling, add 9 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole (the blending ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is 1:1), add 0.5% of the total amount of epoxy resin adhesive and 0.5% of the total amount of resin adhesive light stabilizer (the mass ratio of UV absorber to light stabilizer is 1:1), vacuum stir for 60 minutes, and let stand for later use.

[0127] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0128] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0129] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0130] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0131] S7, Continuous traction: After the prepreg bundle has been cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and pull it out of the core mold continuously.

[0132] S8, Cutting: After the fully cured and pulled continuous core reaches the predetermined length, it is cut into finished products of the required length.

[0133] Comparative Example 3

[0134] This comparative example describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0135] S1, Prepare the resin adhesive: Take 80 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of high-performance glass fiber to aramid fiber of 2:1, 6.5 parts of bisphenol A epoxy resin, 2 parts of epoxy resin 2,2'-[1,6-naphthylbis(oxymethylene)]diepoxide (EBA-65), and 1.6 parts of epoxy resin P-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline (AFG-90MH), stir for 20 minutes, and ultrasonically disperse at 60℃ for 60 minutes.

[0136] After cooling, add 9.5 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole (the blending ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is 1:1), add 0.5% of the total amount of epoxy resin adhesive and 0.5% of the total amount of resin adhesive light stabilizer (the mass ratio of UV absorber to light stabilizer is 1:1), vacuum stir for 60 minutes, and let stand for later use.

[0137] S2, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0138] S3, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank. The fiber bundle after step S3 enters the impregnation tank, so that the fiber is completely impregnated and the resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0139] S4, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0140] S5, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0141] S6, Continuous traction: After the prepreg bundle has been cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and pull it out of the core mold continuously.

[0142] S7, Cutting: After the fully cured and pulled continuous core reaches the predetermined length, it is cut into finished products of the required length.

[0143] Comparative Example 4

[0144] This comparative example describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0145] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0146] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0147] S2, Prepare the resin adhesive: Take 80 parts of a mixture of high-performance glass fiber and aramid fiber, with a mass ratio of 2:1 between the high-performance glass fiber and aramid fiber, 8 parts of bisphenol A epoxy resin, 2 parts of phenolic epoxy resin (F48), stir for 20 minutes, add 1 part of α-nano alumina treated in step S1 and stir evenly, and ultrasonically disperse at 60°C for 60 minutes.

[0148] After cooling, add 9 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole (the blending ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is 1:1), add 0.5% of the total amount of epoxy resin adhesive and 0.5% of the total amount of resin adhesive light stabilizer (the mass ratio of UV absorber to light stabilizer is 1:1), vacuum stir for 60 minutes, and let stand for later use.

[0149] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0150] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0151] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0152] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0153] S7, Continuous traction: After the prepreg bundle has been cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and pull it out of the core mold continuously.

[0154] S8, Cutting: After the fully cured and pulled continuous core reaches the predetermined length, it is cut into finished products of the required length.

[0155] Comparative Example 5

[0156] This comparative example describes a method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core, which includes the following steps:

[0157] S1, Pretreatment of α-nano alumina: α-nano alumina was dried in a 120℃ oven for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A 20% concentration of KH560 silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 3 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 30 minutes, the supernatant was removed, and the precipitate was washed three times with ethanol to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 6 hours to obtain the treated α-nano alumina.

[0158] The preparation method of KH560 coupling agent hydrolysis solution is as follows: Mix deionized water and ethanol and stir evenly, wherein the mass ratio of deionized water to ethanol is 8:72. Add KH560 silane coupling agent to prepare a 20% KH550 hydrolysis solution. Adjust the pH of the solution to 4 with dilute acetic acid and formic acid, stir evenly, and age at 60°C in the dark for 60 minutes.

[0159] S2, Prepare the resin adhesive: Take 80 parts of E glass fiber (elastic modulus 72GPa), the mass ratio of high-performance glass fiber to aramid fiber is 2:1, 10 parts of bisphenol A epoxy resin, stir for 20 minutes, add 1 part of α nano alumina treated in step S1 and stir evenly, and ultrasonically disperse at 60℃ for 60 minutes.

[0160] After cooling, add 9 parts of methyltetrahydrophthalic anhydride, 0.1 parts of a blend of tris(dimethylaminomethyl)phenol and 0.1 parts of 2-ethyl-4-methylimidazole (the blending ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole is 1:1), add 0.5% of the total amount of epoxy resin adhesive and 0.5% of the total amount of resin adhesive light stabilizer (the mass ratio of UV absorber to light stabilizer is 1:1), vacuum stir for 60 minutes, and let stand for later use.

[0161] S3, Fiber Treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. Guided by the yarn guides, the fibers are ensured to be evenly distributed and parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 100°C for 90 seconds.

[0162] S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank, and the fiber bundle after step S3 enters the impregnation tank to completely impregnate the fiber. The resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers.

[0163] S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density.

[0164] S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold by the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: 90°C inlet zone, 170°C gel / curing zone, and 175°C post-curing zone. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold.

[0165] S7, Continuous traction: After the prepreg bundle has been cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and pull it out of the core mold continuously.

[0166] S8, Cutting: After the fully cured and pulled continuous core reaches the predetermined length, it is cut into finished products of the required length.

[0167] Table 1 shows the bending strength, bending modulus, tensile strength, tensile modulus, and thermal stability at 150°C of the insulating cores prepared according to Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3, 4, 5.

[0168] Table 1 Data for each insulating core

[0169] Bending strength / MPa Flexural modulus / GPa Tensile strength / MPa Tensile modulus / GPa Thermal stability at 150℃ Example 1 1758 58.75 1747 59.90 qualified Example 2 1702 57.87 1711 58.70 qualified Example 3 1624 56.68 1657 56.63 qualified Example 4 1580 54.88 1605 54.56 qualified Comparative Example 1 1639 54.90 1650 55.60 qualified Comparative Example 2 1650 55.83 1698 55.75 qualified Comparative Example 3 1624 55.38 1675 54.92 qualified Comparative Example 4 1620 53.55 1655 54.20 qualified Comparative Example 5 650 35.25 720 37.46 Micro cracks

[0170] As shown in Table 1, when high-performance glass fiber and aramid fiber are used as reinforcing materials, and the fiber content is 80%, the system composed of bisphenol A epoxy resin, difunctional naphthyl epoxy resin, and trifunctional aniline epoxy resin achieves a flexural strength of 1702 MPa and a flexural modulus of 57.87 GPa. In contrast, the system composed of bisphenol A epoxy resin and phenolic epoxy resin only achieves a flexural strength of 1620 MPa and a flexural modulus of only 53.55 GPa. The former exhibits a flexural strength 82 MPa higher and a flexural modulus 4.32 GPa higher than the latter. This indicates that the bisphenol A epoxy resin blended with difunctional naphthyl epoxy resin and trifunctional aniline epoxy resin system used in this invention significantly improves the flexural modulus and flexural strength of the insulating core compared to the bisphenol A epoxy resin and phenolic epoxy resin system alone.

[0171] Comparing Example 2 and Comparative Example 1, under the same fiber content, Comparative Example 1, without the addition of naphthyl epoxy resin (2,2'-[1,6-naphthylbis(oxymethylene)]diepoxyethylene), showed a decrease in flexural strength of 63 MPa and a decrease in flexural modulus of 2.97 GPa after adjusting the proportions of other components. This result confirms that naphthyl epoxy resin plays a significant role in improving the modulus of the insulating core. Comparing Example 2 and Comparative Example 2, under the same fiber content, Comparative Example 2, without the addition of the trifunctional epoxy resin P-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline (AFG-90MH), showed a decrease in flexural strength of 52 MPa and a decrease in flexural modulus of 2.04 GPa after adjusting the proportions of other components. This indicates that trifunctional aniline epoxy resin is also crucial for improving the modulus of the insulating core. Comparing Example 2 and Comparative Example 3, under the same fiber content, Comparative Example 3, without the addition of α-nano alumina, showed a decrease in flexural strength of 78 MPa and a decrease in flexural modulus of 2.49 GPa after adjusting other components proportionally. This indicates that adding α-nano alumina can significantly improve the flexural modulus and flexural strength of the insulating core. Comparing Example 2 and Comparative Example 5, Comparative Example 5 replaced the combination of high-performance glass fiber and aramid fiber with ordinary E-glass fiber, and replaced the high-performance epoxy resin combination with ordinary bisphenol A epoxy resin. Compared with the insulating core prepared in Example 2, the insulating core prepared in Comparative Example 5 showed a decrease in flexural strength of 61.8% and a decrease in flexural modulus of 39%, and microcracks appeared in the 150℃ temperature resistance test. It is precisely due to the synergistic reinforcing effect of high-performance glass fiber and aramid fiber, the optimized combination of several epoxy resins, the reinforcing effect of α-nano alumina, and the interface treatment between the fiber and resin, that the insulating core possesses high flexural strength and flexural modulus, thus meeting the requirements of UHV props for high strength and high modulus.

[0172] As can be seen from Table 1 and Examples 1-4, the flexural modulus of the insulating core increases significantly with the increase of fiber content. The increase is approximately linear, with fiber contribution being dominant.

[0173]

[0174] In the above formula, Indicates fiber content, Indicates the composite core modulus. Indicates fiber modulus. This indicates the modulus of epoxy resin.

[0175] Similarly, the bending strength of the insulating core is affected by the resin interface, and under the condition of maintaining consistent interfacial adhesion, it is also approximately proportional to the fiber content.

[0176]

[0177] In the above formula, Indicates the bending strength of the composite core. Indicates fiber bending strength. This indicates the modulus and flexural strength of epoxy resin. This indicates the fiber content.

[0178] Higher fiber content is not always better. Excessive fiber content and insufficient resin content will weaken the interfacial bonding between fibers, making them prone to delamination and damage, reducing toughness, decreasing impact resistance, and increasing brittleness. Excessive fiber content may also prevent the resin from fully encapsulating the fibers, resulting in dry spots and porosity. Furthermore, excessive fiber content increases friction within the core mold, potentially breaking fibers or damaging equipment, leading to a rough core surface and the appearance of white fibers.

[0179] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A high-modulus, high-temperature resistant fiber pultruded insulating core, characterized in that: The raw materials for its preparation include the following components by weight: 75-85 parts of a mixture of high-performance glass fiber and aramid fiber, wherein the mass ratio of high-performance glass fiber to aramid fiber is (1-10):1, and 15-25 parts of epoxy resin. The epoxy resin adhesive comprises the following components by weight: 6.5 to 14.5 parts epoxy resin, 6.5 to 14 parts curing agent, and 0.2 to 1 part accelerator, wherein the mass ratio of epoxy resin to curing agent is 100:(90 to 110). The epoxy resin comprises the following components in parts by weight: 4.5 to 9 parts of bisphenol A epoxy resin; 1-3 parts of difunctional naphthyl epoxy resin; 1-2.5 parts of trifunctional aniline epoxy resin; The mass ratio of bisphenol A epoxy resin, difunctional naphthyl epoxy resin and trifunctional aniline epoxy resin is 12:(2~5):(3~6).

2. The high-modulus, high-temperature resistant fiber pultruded insulating core according to claim 1, characterized in that: The difunctional naphthyl epoxy resin is 2,2'-[1,6-naphthylbis(oxomethylene)]diepoxyethylene; The trifunctional aniline epoxy resin is a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin.

3. The high-modulus, high-temperature resistant fiber pultruded insulating core according to claim 1, characterized in that: The bisphenol A epoxy resin has an epoxy equivalent of 185-208.

4. The high-modulus, high-temperature resistant fiber pultruded insulating core according to claim 1, characterized in that: The curing agent is methyltetrahydrophthalic anhydride.

5. The high-modulus, high-temperature resistant fiber pultruded insulating core according to claim 1, characterized in that: The accelerator comprises a mixture of tris(dimethylaminomethyl)phenol and 2-ethyl-4-methylimidazole, with a mass ratio of tris(dimethylaminomethyl)phenol to 2-ethyl-4-methylimidazole of (1-3):1, and the accelerator accounts for 0.5% to 2% of the total amount of epoxy resin.

6. The high-modulus, high-temperature resistant fiber pultruded insulating core according to claim 1, characterized in that: The epoxy resin adhesive also includes 0.5 to 1.5 parts of functional filler, which is α-nano alumina treated with a silane coupling agent. The silane coupling agent is 3-aminopropyltriethoxysilane or 3-(2,3-epoxypropoxy)propyltrimethoxysilane. The particle size of the α-nano alumina is 10 to 100 nm, and the α-nano alumina accounts for 3% to 5% of the total amount of epoxy resin adhesive.

7. The high-modulus, high-temperature resistant fiber pultruded insulating core according to claim 1, characterized in that: Epoxy resin adhesives also include ultraviolet absorbers and light stabilizers, which account for 0.2% to 1% of the total adhesive content of the epoxy resin adhesive, and the mass ratio of ultraviolet absorbers to light stabilizers is 1:

1.

8. A method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core as described in claims 1 to 7, characterized in that, Includes the following steps: S1, Pretreatment of α-nano alumina: α-nano alumina was dried in an oven at 120℃ for 2 hours to remove physically adsorbed water. 100g of dried mixed alumina was added to 500mL of ethanol and ultrasonically dispersed for 30 minutes. A silane coupling agent hydrolysis solution was prepared. 5g of the silane coupling agent hydrolysis solution was slowly added to the dispersed alumina ethanol solution and stirred at 60℃ for 2-4 hours. After dilution with 100mL of ethanol, the solution was centrifuged for 10-30 minutes to remove the supernatant. The precipitate was washed with ethanol 2-3 times to remove physically adsorbed silane coupling agent. After vacuum filtration, the filter cake was placed in a vacuum oven and dried at 60℃ for 4-8 hours to obtain the treated α-nano alumina. S2, Prepare the resin adhesive: Take 75-85 parts of a mixture of high-performance glass fiber and aramid fiber, 4.5-9 parts of bisphenol A epoxy resin, add 1-3 parts of 2,2'-[1,6-naphthylbis(oxymethylene)]diepoxide, and 1-2.5 parts of a mixture of P-(2,3-epoxypropoxy)-N and N-bis(2,3-epoxypropyl)aniline epoxy resin, stir for 10-20 minutes, add 0.5-1 parts of α-nano alumina treated in step S1, stir evenly, and ultrasonically disperse at 60°C for 30-60 minutes; After cooling, add 6.5–14 parts of methyltetrahydrophthalic anhydride, add 0.5%–2% of the total mass of the resin adhesive as an accelerator, which is a blend of tris(dimethylaminomethyl)phenol and 2-ethyl-4-methylimidazole, with a blending ratio of (1–3):

1. Add 0.2%–1% of the total mass of the epoxy resin adhesive as a UV absorber and a light stabilizer, with a mass ratio of 1:

1. Stir under vacuum for 30–60 minutes and let stand for later use. S3, Fiber treatment: Continuous fibers are drawn from a yarn rack or spool as untwisted rovings. The drawn fibers are introduced into multiple parallel yarn guides to ensure uniform fiber distribution. The yarn guides ensure that the fibers are evenly distributed and arranged in parallel. The fibers are uniformly sprayed under the traction of a traction machine. The spraying uses the silane coupling agent hydrolysis solution from step S1. After spraying, the fibers enter multiple parallel squeezing rollers. The squeezing rollers squeeze the fibers to ensure that the coupling agent fully wets each fiber monofilament, while removing excess coupling agent. The amount of coupling agent adhering to the fiber surface is controlled to be uniform. The fibers then enter a drying oven and are dried at 80-100°C for 30-90 seconds. S4, Resin Impregnation: Pour the resin glue after step S2 into the impregnation tank. The fiber bundle after step S3 enters the impregnation tank, so that the fiber is completely impregnated and the resin glue penetrates between each monofilament. After impregnation, the fiber bundle is led out from the impregnation tank and enters between a pair of extrusion rollers. The excess resin glue on the surface of the fiber bundle is squeezed out by the extrusion rollers. S5, Preforming: After leaving the resin tank, the prepreg bundle enters the forming channel of the preforming device through the guide plate and the compaction roller. The guide plate is used to guide the prepreg bundle smoothly into the forming channel. Under the guidance of the guide plate, the loose fiber bundle is initially gathered together. The prepreg bundle is gradually compacted by the compaction roller to remove excess resin, and the loose fiber bundle is initially gathered and compacted to guide it into a tight bundle that is close to the shape of the final product. Air bubbles are also removed to improve the density. S6, Molding and Curing: The prepreg bundle after preforming in step S5 is slowly drawn into the molding cavity of the core mold under the traction of the traction machine. The core mold adopts precise segmented heating to form different temperature gradient zones: entrance zone 80-100°C, gel / curing zone 160-180°C, and post-curing zone 170-175°C. As the temperature rises in the core mold, the resin gradually undergoes gelation and curing reactions. At the same time, under the constraint of the traction pressure and the molding cavity of the core mold, it forms a shape consistent with the molding cavity of the core mold. S7, Continuous traction and cutting: After the prepreg bundle is cured in the core mold in step S6, the traction machine is turned on to clamp the core at a constant speed and continuously pull it out of the core mold. After the continuously cured and pulled core reaches the predetermined length, it is cut into finished products of the required length.

9. The method for preparing a high-modulus, high-temperature resistant fiber pultruded insulating core according to claim 8, characterized in that, The silane coupling agent is KH550 coupling agent or KH560 coupling agent; The method for preparing the KH550 coupling agent hydrolysis solution is as follows: deionized water and ethanol are mixed and stirred evenly, wherein the mass ratio of deionized water to ethanol is 8:

72. KH550 silane coupling agent is added and stirred until completely dissolved to prepare a KH550 hydrolysis solution with a concentration of 20%. The solution is then aged at 60°C in the dark for 30 to 60 minutes. The preparation method of the KH560 coupling agent hydrolysis solution is as follows: deionized water and ethanol are mixed and stirred evenly, wherein the mass ratio of deionized water to ethanol is 8:

72. KH560 silane coupling agent is added to prepare a 20% KH560 hydrolysis solution. The pH of the solution is adjusted to 4-5 with dilute acetic acid and formic acid. The solution is stirred evenly and aged at 60°C in the dark for 30-60 minutes.

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