Low-smoke halogen-free flame-retardant power cable insulation material

Abstract

The application discloses a low-smoke halogen-free flame-retardant power cable insulating material, and belongs to the technical field of cable insulating materials, and aims at solving the technical problem that the flame-retardant, low-smoke, insulating and aging-resistant performance of the power cable insulating material in the prior art needs to be further improved. The low-smoke halogen-free flame-retardant power cable insulating material comprises the following components in parts by weight: 40-50 parts of medium-density polyethylene, 22-26 parts of low-density polyethylene, 8-9 parts of MAH-g-PE, 38-46 parts of EVA, 50-60 parts of captured modified magnesium hydroxide, 18-22 parts of borosilicon ceramic modified particles, 0.9-1.3 parts of an initiator and 3-5 parts of an additive. The low-smoke halogen-free flame-retardant power cable insulating material has the advantages that, by taking polyethylene and EVA composite resin as a matrix, and by adding captured modified magnesium hydroxide and borosilicon ceramic modified particles, the flame-retardant, low-smoke, insulating and aging-resistant performance of the material is improved.

Description

Technical Field

[0001] This invention relates to the field of cable insulation materials technology, specifically to a low-smoke, halogen-free, flame-retardant power cable insulation material. Background Technology

[0002] 10kV power cables are medium-voltage power transmission lines, primarily responsible for supplying power over medium distances and heavy loads, offering wide coverage and high efficiency. Traditional 10kV power cables often use polyvinyl chloride or ordinary halogenated flame-retardant polyolefins as insulation and sheathing materials. In fire conditions, these cables release large amounts of toxic and corrosive fumes containing hydrogen halides, which not only quickly obscure evacuation visibility and significantly increase the difficulty of escape, but also cause irreversible secondary corrosion damage to precision electrical equipment and communication control systems.

[0003] Existing low-smoke halogen-free flame-retardant cable materials typically use polyolefin resins such as polyethylene and ethylene-vinyl acetate copolymer as the matrix, and add inorganic flame retardants such as magnesium and aluminum to improve the flame retardant effect. To obtain a high flame retardant rating, a relatively large amount of inorganic flame retardant is usually required. However, high filler content leads to difficulties in the dispersion of fillers in the resin, poor interfacial bonding, and problems such as agglomeration, micropores, and interfacial debonding, thereby reducing the tensile strength, elongation at break, and processing stability of the material. For power cable insulation materials, in addition to flame retardant performance, high volume resistivity, good dielectric stability, and performance retention after thermal aging are also required. However, ordinary inorganic flame retardants have strong surface polarity and easily adsorb moisture, resulting in insufficient compatibility in the polyolefin matrix, which can cause interfacial defects and a decline in electrical performance. At the same time, during long-term thermo-oxidative aging, interfacial defects inside the material can easily become the starting point for crack propagation and performance degradation, leading to a decrease in insulation performance, mechanical properties, and flame retardant stability.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a low-smoke, halogen-free, flame-retardant power cable insulation material, which addresses the technical problem that the flame retardancy, low smoke, insulation, and aging resistance of existing power cable insulation materials need further improvement.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A low-smoke, halogen-free, flame-retardant power cable insulation material comprises the following components in parts by weight: 40-50 parts of medium-density polyethylene, 22-26 parts of low-density polyethylene, 8-9 parts of MAH-g-PE, 38-46 parts of EVA, 50-60 parts of trap-type modified magnesium hydroxide, 18-22 parts of borosilicate ceramic modified particles, 0.9-1.3 parts of initiator, and 3-5 parts of additives;

[0008] The captured modified magnesium hydroxide is obtained by treating zinc-aluminum coated magnesium hydroxide with vinyltriethoxysilane and 3-aminopropyltriethoxysilane;

[0009] The borosilicate ceramicized modified particles are obtained by treating flaky mica powder and zinc stannate-coated glass powder with a borosilicate modification solution.

[0010] Furthermore, the initiator is dicumyl peroxide, and the additives are composed of stearate, antioxidant 1010, antioxidant 168, polyethylene wax and silicone powder in a weight ratio of 5:2:2:3:2.

[0011] Furthermore, the preparation method of the captured modified magnesium hydroxide includes the following steps: mixing and stirring zinc-aluminum coated magnesium hydroxide, ethanol aqueous solution, vinyltriethoxysilane and 3-aminopropyltriethoxysilane, adding sodium hydroxide solution to the reaction system, heating the reaction system to 60-70℃, maintaining the temperature for 4-5 hours, and then performing post-treatment to obtain captured modified magnesium hydroxide.

[0012] Furthermore, the ratio of zinc-aluminum coated magnesium hydroxide, ethanol aqueous solution, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, and sodium hydroxide solution is 10g:100mL:1.3-1.5g:0.3-0.4g:5mL. The ethanol aqueous solution is composed of anhydrous ethanol and deionized water in a volume ratio of 7:3. The concentration of the sodium hydroxide solution is 3-5mol / L. The post-treatment includes: cooling to room temperature after the reaction is completed, filtration, washing the filter cake with deionized water until neutral, drying it under vacuum, and then drying it at 70-80℃ to constant weight to obtain the captured modified magnesium hydroxide.

[0013] Furthermore, the preparation method of the zinc-aluminum coated magnesium hydroxide is as follows: zinc nitrate, aluminum nitrate and deionized water are mixed and stirred until the system is dissolved. Nano magnesium hydroxide is added to the reaction system. The reaction system is heated to 68-72℃ and stirred for 20-30 min. Sodium phenylphosphinate and boric acid are added to the reaction system. Then sodium hydroxide solution is added to the reaction system to adjust the pH of the system to 9-9.5. The reaction is kept at the temperature for 3-4 h. After post-treatment, zinc-aluminum coated magnesium hydroxide is obtained.

[0014] Furthermore, the ratio of zinc nitrate, aluminum nitrate, deionized water, nano magnesium hydroxide, sodium phenylphosphinate, and boric acid is 1.8g:1g:500mL:60-65g:1.1-1.2g:0.35-0.45g, the concentration of the sodium hydroxide solution is 3-5mol / L, and the post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with deionized water until neutral, dried under vacuum, and then dried at 70-80℃ to constant weight to obtain zinc-aluminum coated magnesium hydroxide.

[0015] Furthermore, the preparation method of the borosilicate ceramic modified particles is as follows: flaky mica powder and zinc stannate-coated glass powder are added to a high-speed mixer, the mixer speed is set to 15-18 r / min, borosilicate modified liquid is sprayed into the mixer, and after spraying, the mixture is mixed for 20-30 min. Then, the mixer temperature is raised to 115-125℃ and dried for 60-80 min. Then, the mixer temperature is raised to 145-155℃ and kept at that temperature for 80-100 min. The mixture is then allowed to cool naturally to room temperature and discharged to obtain borosilicate ceramic modified particles.

[0016] Furthermore, the weight ratio of the flake mica powder to the zinc stannate-coated glass powder is 5:2, and the liquid-solid ratio of the borosilicate modified liquid to the solid material composed of the flake mica powder and the zinc stannate-coated glass powder is 1:7.

[0017] Furthermore, the preparation method of the borosilicate modified solution is as follows: Tetraethyl orthosilicate, trimethyl borate, phenyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, triethoxysilane-modified hindered phenol, ethanol, and deionized water are mixed and stirred. Acetic acid is added to the reaction system to adjust the pH to 4-5. The system is pre-hydrolyzed at room temperature for 40-50 minutes to obtain the borosilicate modified solution. The ratio of the amounts of tetraethyl orthosilicate, trimethyl borate, phenyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, ethanol, and deionized water is 4-5 g: 1-1.2 g: 1.2-1.4 g: 0.9-1.1 g: 0.7-0.8 g: 60 mL: 10 mL.

[0018] Furthermore, the preparation method of the zinc stannate-coated glass powder includes the following steps:

[0019] A1. Place low-melting-point alkali-free glass powder in a sodium hydroxide solution at a temperature of 50-60℃ and stir to disperse for 20-30 minutes. Then, perform post-treatment to obtain activated glass powder.

[0020] A2. Mix and stir activated glass powder and deionized water. Heat the reaction system to 65-75℃. Simultaneously add zinc nitrate solution and sodium stannate solution to the reaction system. After the addition is complete, add ammonia water to the reaction system to adjust the pH of the system to 8.2-8.8. Keep the system warm and stir for 3-5 hours. After post-processing, zinc stannate coated glass powder is obtained.

[0021] Further, in step A1, the solid-liquid ratio of the low-melting-point alkali-free glass powder and the sodium hydroxide solution is 1:7-8, the concentration of the sodium hydroxide solution is 5-6 mol / L, and the post-processing operation includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 60-70℃ and dried to constant weight to obtain activated glass powder.

[0022] Further, in step A2, the ratio of activated glass powder, deionized water, zinc nitrate solution, and sodium stannate solution is 5g:50mL:110mL:100mL. The zinc nitrate solution is an aqueous solution of zinc nitrate hexahydrate with a concentration of 0.1mol / L, and the sodium stannate solution is an aqueous solution of sodium stannate trihydrate with a concentration of 0.1mol / L. The post-processing operation includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, dried, and the filter cake is transferred to a drying oven at a temperature of 110-120℃ and dried to constant weight to obtain zinc stannate-coated glass powder.

[0023] The present invention has the following beneficial effects:

[0024] 1. The low-smoke halogen-free flame-retardant power cable insulation material of the present invention, through in-situ deposition of zinc aluminum hydroxide on the surface of magnesium hydroxide and introduction of phosphorus and boron components, and then through the hydrolysis and condensation reaction of vinyl silane and amino silane to form silane surface modification on the particle surface, transforms the filler from a single inorganic flame-retardant particle into a composite functional particle with endothermic decomposition, char formation promotion and interfacial reaction capabilities. During combustion, low-melting-point glass powder and borosilicate components can form a glassy binder phase, mica sheets provide skeletal support, zinc stannate promotes char formation and reduces smoke generation, forming a continuous and dense protective layer. Magnesium hydroxide reduces the system temperature through dehydration and endothermic action. With the synergistic effect of zinc, aluminum, phosphorus and boron, a dense inorganic residual layer is formed and smoke generation is suppressed. At the same time, the material system is ceramicized by borosilicate modification liquid, which significantly reduces polar water absorption and interfacial defects. This allows the material to maintain a high volume resistivity, a high oxygen index and excellent tensile toughness in a high-filling halogen-free flame-retardant system, and maintain relatively stable electrical and mechanical properties after thermal aging.

[0025] 2. The low-smoke halogen-free flame-retardant power cable insulation material of the present invention, through the combination of MAH-g-PE, vinylsilane, aminosilane, methacryloyloxysilane, and dicumyl peroxide, allows the maleic anhydride groups to form a strong bond with the amino and hydroxyl groups on the filler surface. The unsaturated groups can participate in cross-linking under the action of peroxides, transforming the inorganic filler from simple dispersed particles in the resin into functional nodes that can connect with the polymer network. This strengthens the interfacial bonding between the resin matrix and the inorganic filler, reducing filler agglomeration, interfacial debonding, and stress concentration. Furthermore, this material can withstand the addition of more magnesium hydroxide... Even after removing inorganic components such as mica and glass powder, the material still maintains high tensile strength and elongation at break. Furthermore, the cross-linking structure between materials reduces the migration rate of small molecule additives, oxidation products, and moisture within the material, slowing down the diffusion rate of oxygen into the material. Simultaneously, the hindered phenolic main antioxidant can capture peroxide free radicals and alkyl free radicals, terminating the free radical chain reaction of polymer thermo-oxidative aging, converting highly reactive free radicals into more stable, less reactive structures, and reducing molecular chain breakage. During thermal aging, the hindered phenols and interfacial bonding work together to reduce crack propagation and oxidative damage, thereby improving the performance retention rate after aging. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 X-ray diffraction patterns of zinc-aluminum coated magnesium hydroxide and nano-magnesium hydroxide prepared in Example 1 of this invention;

[0028] Figure 2 This is an X-ray diffraction pattern of zinc stannate-coated glass powder and activated glass powder in Example 4 of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] In this application, the medium-density polyethylene is a commercially available product, branded as Qatar Chemicals, grade HHM3802, with an effective ingredient content of 98% and a processing grade of injection molding.

[0031] In this application, the low-density polyethylene is a commercially available product, branded as Sinopec Maoming, and the processing grade is injection molding grade;

[0032] In this application, MAH-g-PE is commercially available maleic anhydride-grafted polyethylene with a maleic anhydride grafting rate of 1%;

[0033] In this application, EVA is a commercially available product with a VA content of 15% and a processing grade of injection molding grade;

[0034] In this invention, the nano-magnesium hydroxide is a commercially available product with a particle size of 30-50 nm and a mass fraction of 99.9%.

[0035] In this invention, the low-melting-point alkali-free glass powder is a commercially available product with a melting point of 450-600℃ and a content of 95%.

[0036] In this invention, the flake mica powder is a commercially available product with a particle size of 15-19 μm.

[0037] Preparation Example 1

[0038] This preparation example provides a method for preparing a trap-type modified magnesium hydroxide, specifically including the following steps:

[0039] Step 1: Preparation of zinc-aluminum coated magnesium hydroxide

[0040] Weigh out 18g of zinc nitrate, 10g of aluminum nitrate, and 5L of deionized water and add them to a reaction vessel. Stir until the system is dissolved. Add 600g of nano-magnesium hydroxide to the reaction vessel. Heat the reaction vessel to 68℃ and stir for 20min. Add 11g of sodium phenylphosphinate and 3.5g of boric acid to the reaction vessel. Add 3mol / L sodium hydroxide solution to the reaction vessel and adjust the pH of the system to 9. Keep the reaction vessel at this temperature for 3h. Cool the reaction vessel to room temperature, filter, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain zinc-aluminum coated magnesium hydroxide.

[0041] In the reaction, zinc nitrate and aluminum nitrate dissolve in water to form Zn, respectively. 2+ And Al 3+ When nano-magnesium hydroxide is added to an aqueous system, its surface contains a large number of hydroxyl sites that can electrostatically adsorb metal ions, and can also adsorb Zn through surface coordination. 2+ Al 3+This provides nucleation sites for the in-situ deposition of the subsequent coating layer. After the addition of sodium phenylphosphine and boric acid, sodium phenylphosphine provides phosphorus-containing anionic groups in water, and boric acid gradually converts to borate under alkaline conditions. These phosphorus- and boron-containing components enter the zinc-aluminum hydroxide coating layer through coordination, hydrogen bonding, or ionic interactions, forming a composite inorganic / organic flame-retardant interface containing phosphorus and boron. Magnesium hydroxide decomposes endothermally at high temperatures, releasing moisture and generating MgO; the aluminum hydroxyl component can undergo endothermic dehydration at lower temperatures; the boron component easily forms glassy B2O3 or borate structures during combustion; the phosphorus component promotes char formation in the condensed phase and forms a phosphate protective layer. The zinc, aluminum, phosphorus, and boron components form a synergistic flame-retardant system, jointly reducing the surface temperature of the material, blocking oxygen and heat transfer, and reducing the release of combustible pyrolysis products. The zinc component has a certain smoke-suppressing and char-catalyzing effect. During combustion, zinc compounds can promote the conversion of polymer pyrolysis products into condensed phase char, reduce the generation of volatile soot precursors, and improve the light transmittance in smoke density testing.

[0042] Appendix Figure 1 X-ray diffraction patterns of zinc-aluminum coated magnesium hydroxide and nano-magnesium hydroxide are presented. In the X-ray diffraction patterns, nano-magnesium hydroxide exhibits typical diffraction peaks at approximately 18.5°, 38.0°, 50.7°, 58.8°, and 62.0° at 2θ. Zinc-aluminum coated magnesium hydroxide retains the same diffraction peaks in the same 2θ range, indicating that the coating treatment did not destroy the main crystal structure of magnesium hydroxide. Compared with nano-magnesium hydroxide, the zinc-aluminum coated sample shows new weak and broad diffraction peaks at approximately 11.6° and 23.3° at 2θ, and low-intensity additional peaks or shoulder peaks near 34.6°, 39.1°, 46.6°, and 60.6°, corresponding to the crystal plane reflection of the Zn-Al layered hydroxyl phase, indicating that a coating layer containing zinc-aluminum hydroxyl structure has been formed on the sample surface. The main peak intensity of magnesium hydroxide in the coated sample is relatively reduced and the peak shape is slightly broadened, indicating that the outer layer deposition has a shielding and scattering effect on the diffraction of magnesium hydroxide crystal planes.

[0043] Step 2: Capture-type modified magnesium hydroxide

[0044] Anhydrous ethanol and deionized water were mixed evenly at a volume ratio of 7:3 to obtain an ethanol-water solution.

[0045] Weigh out 500g of zinc-aluminum coated magnesium hydroxide, 65g of vinyltriethoxysilane, 15g of 3-aminopropyltriethoxysilane, and 5L of ethanol aqueous solution and add them to a reaction vessel. Mix and stir. Add 250mL of 3mol / L sodium hydroxide solution to the reaction vessel. Heat the reaction vessel to 60℃ and keep it at that temperature for 4h. Cool the reaction vessel to room temperature, filter, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain the captured modified magnesium hydroxide.

[0046] In the reaction, vinyltriethoxysilane and 3-aminopropyltriethoxysilane undergo hydrolysis in an aqueous ethanol solution. The ethoxy groups are gradually converted to silanol groups. After hydrolysis, vinyltriethoxysilane retains the vinyl groups, and 3-aminopropyltriethoxysilane retains the aminopropyl groups. The generated silanol groups further undergo condensation reactions with the inorganic particle surface, forming surface modification and yielding captured modified magnesium hydroxide. The vinyl groups on the captured modified magnesium hydroxide particles participate in free radical reactions during subsequent peroxide crosslinking, polymerizing with PE and EVA molecular chains to form polymers. The amino groups can undergo ring-opening reactions or form strong polar interactions with the maleic anhydride groups in MAH-g-PE, easily forming amyl acid structures. Under processing heat, a more stable imide interface structure is formed. The siloxane layer also significantly reduces the hydrophilicity of the magnesium hydroxide surface, changing the particle surface from strongly hydrophilic to organic-loving, making the interface between the filler and the PE / EVA matrix more compact, reducing interfacial porosity and moisture accumulation, thereby improving the volume resistivity of the material.

[0047] Preparation Example 2

[0048] This preparation example provides a method for preparing a trap-type modified magnesium hydroxide, specifically including the following steps:

[0049] Step 1: Preparation of zinc-aluminum coated magnesium hydroxide

[0050] Weigh out 18g of zinc nitrate, 10g of aluminum nitrate, and 5L of deionized water and add them to a reaction vessel. Stir until the system is dissolved. Add 625g of nano-magnesium hydroxide to the reaction vessel. Heat the reaction vessel to 70℃ and stir for 25min. Add 11.5g of sodium phenylphosphinate and 4.0g of boric acid to the reaction vessel. Add 4mol / L sodium hydroxide solution to the reaction vessel and adjust the pH of the system to 9.3. Keep the reaction vessel at this temperature for 3.5h. Cool the reaction vessel to room temperature, filter, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 75℃ and dry it to constant weight to obtain zinc-aluminum coated magnesium hydroxide.

[0051] Step 2: Capture-type modified magnesium hydroxide

[0052] Anhydrous ethanol and deionized water were mixed evenly at a volume ratio of 7:3 to obtain an ethanol-water solution.

[0053] Weigh out 500g of zinc-aluminum coated magnesium hydroxide, 70g of vinyltriethoxysilane, 17.5g of 3-aminopropyltriethoxysilane, and 5L of ethanol aqueous solution and add them to a reaction vessel. Mix and stir. Add 250mL of 4mol / L sodium hydroxide solution to the reaction vessel. Heat the reaction vessel to 65℃ and keep it at that temperature for 4.5h. Cool the reaction vessel to room temperature, filter, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 75℃ and dry it to constant weight to obtain the trap-type modified magnesium hydroxide.

[0054] Preparation Example 3

[0055] This preparation example provides a method for preparing a trap-type modified magnesium hydroxide, specifically including the following steps:

[0056] Step 1: Preparation of zinc-aluminum coated magnesium hydroxide

[0057] Weigh out 18g of zinc nitrate, 10g of aluminum nitrate, and 5L of deionized water and add them to a reaction vessel. Stir until the system is dissolved. Add 650g of nano-magnesium hydroxide to the reaction vessel. Heat the reaction vessel to 72℃ and stir for 30min. Add 12g of sodium phenylphosphinate and 4.5g of boric acid to the reaction vessel. Add 5mol / L sodium hydroxide solution to the reaction vessel and adjust the pH of the system to 9.5. Keep the reaction vessel at this temperature for 4h. Cool the reaction vessel to room temperature, filter, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight to obtain zinc-aluminum coated magnesium hydroxide.

[0058] Step 2: Capture-type modified magnesium hydroxide

[0059] Anhydrous ethanol and deionized water were mixed evenly at a volume ratio of 7:3 to obtain an ethanol-water solution.

[0060] Weigh out 500g of zinc-aluminum coated magnesium hydroxide, 75g of vinyltriethoxysilane, 20g of 3-aminopropyltriethoxysilane, and 5L of ethanol aqueous solution and add them to a reaction vessel. Mix and stir. Add 250mL of 5mol / L sodium hydroxide solution to the reaction vessel. Heat the reaction vessel to 70℃ and keep it at that temperature for 5h. Cool the reaction vessel to room temperature, filter, wash the filter cake with deionized water until neutral, and then dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight to obtain the captured modified magnesium hydroxide.

[0061] Preparation Example 4

[0062] This preparation example provides a method for preparing borosilicate ceramicized modified particles, specifically including the following steps:

[0063] Step I: Preparation of activated glass powder

[0064] Low-melting-point alkali-free glass powder and 5 mol / L sodium hydroxide solution were added to a reaction vessel at a solid-liquid ratio of 1:7 and stirred. The reaction vessel was heated to 50°C and stirred for 20 min. The mixture was then filtered, and the filter cake was washed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 60°C and dried to constant weight to obtain activated glass powder.

[0065] Step II: Preparation of zinc stannate-coated glass powder

[0066] Zinc nitrate hexahydrate was dissolved in deionized water to obtain a zinc nitrate solution with a concentration of 0.1 mol / L.

[0067] Sodium stannate trihydrate was dissolved in deionized water to obtain a sodium stannate solution with a concentration of 0.1 mol / L.

[0068] Weigh out 50g of activated glass powder and 500mL of deionized water and add them to the reaction vessel. Stir the reaction vessel and heat it to 65℃. Add 1.1L of zinc nitrate solution and 1L of sodium stannate solution dropwise to the reaction vessel. After the addition is complete, add ammonia water to the reaction vessel to adjust the pH of the system to 8.2. Keep the mixture warm and stir for 3 hours. Cool the reaction vessel to room temperature and filter it. Wash the filter cake with purified water until it is neutral and then dry it. Transfer the filter cake to a drying oven at 110℃ and dry it to constant weight to obtain zinc stannate coated glass powder.

[0069] In the reaction, zinc nitrate solution provides Zn. 2+ Sodium stannate solution provides stannate ions. After contact in the aqueous phase, a precipitation reaction occurs, forming hydrated zinc stannate deposits. This activates the silanol sites on the surface of the glass powder, enabling the adsorption of Zn. 2+ The presence of stannate or zinc stannate groups allows for preferential heterogeneous nucleation of zinc stannate on the surface of glass powder, resulting in zinc stannate-coated glass powder. Zinc stannate is often used as a smoke-suppressing synergist in halogen-free flame-retardant systems. Its zinc and tin centers exhibit Lewis acid characteristics, promoting cross-linking, dehydrogenation, and char formation of polymer thermal decomposition products, thus reducing the release of small-molecule combustible volatiles and soot precursors. Simultaneously, zinc stannate itself is an inorganic heat-resistant phase, which can improve the strength and stability of combustion residues.

[0070] Appendix Figure 2 The X-ray diffraction patterns of zinc stannate-coated glass powder and activated glass powder are presented. The activated glass powder itself does not have obvious sharp diffraction peaks, but instead exhibits a relatively broad and gentle diffuse peak between approximately 20° and 35°, indicating that the glass powder is mainly an amorphous glassy structure. Compared to activated glass powder, the zinc stannate-coated glass powder shows new sharp diffraction peaks near 22.9°, 32.6°, 40.2°, and 46.8°, indicating that Zn... 2+ It reacts with stannate ions in a weakly alkaline aqueous phase to precipitate, forming a zinc stannate coating.

[0071] Step III: Preparation of borosilicate modified solution

[0072] Weigh 23.6 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol and 100 mL of tetrahydrofuran into a reaction flask under nitrogen protection and stir. Heat the reaction flask to 40 °C, add 24.7 g of propyltriethoxysilane isocyanate, keep the reaction at this temperature for 60 min, and then apply a negative pressure of -0.1 MPa to the reaction flask. Remove low-boiling substances by vacuum distillation to obtain triethoxysilane-modified hindered phenol.

[0073] Weigh out 40g of tetraethyl orthosilicate, 10g of trimethyl borate, 12g of phenyltrimethoxysilane, 9g of 3-(methacryloyloxy)propyltrimethoxysilane, 7g of triethoxysilane-modified hindered phenol, 600mL of ethanol and 100mL of deionized water, add them to the reaction flask and stir. Add acetic acid to the reaction flask to adjust the pH of the system to 4. Pre-hydrolyze at room temperature for 40min to obtain borosilicate modified solution.

[0074] In the reaction, the benzyl alcohol hydroxyl group in the 3,5-di-tert-butyl-4-hydroxybenzyl alcohol molecule undergoes an addition reaction with the highly reactive isocyanate group in propyltriethoxysilane to form a carbamate bond, yielding triethoxysilane-modified hindered phenol. After mixing tetraethyl orthosilicate, trimethyl borate, phenyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, triethoxysilane-modified hindered phenol, ethanol, and water, the siloxane bonds are hydrolyzed. Due to the pH being controlled at a weakly acidic level, the hydrolysis is relatively complete and the condensation rate is relatively controllable, resulting in a sprayable and coating-compatible borosilicate modified liquid.

[0075] Tetraethyl orthosilicate provides a SiO2 network; trimethyl borate provides a boron-oxygen structure, which is beneficial for forming a low-melting glassy protective layer during combustion; phenyltrimethoxysilane introduces phenyl groups, improving compatibility with the organic matrix and facilitating the formation of aromatic char residues at high temperatures; methacryloxypropyltrimethoxysilane introduces double bonds that can undergo free radical reactions, allowing for grafting or co-crosslinking with PE / EVA segments under the action of peroxides; and silane-modified hindered phenols provide immobilized antioxidant functions.

[0076] Step IV: Preparation of borosilicate ceramic-modified particles

[0077] Weigh out 1500g of flake mica powder and 600g of zinc stannate-coated glass powder and add them to a high-speed mixer. Set the mixer speed to 15r / min. Spray 300mL of borosilicate modification liquid into the mixer. After spraying, mix for 20min. Raise the mixer temperature to 115℃ and dry for 60min. Then raise the mixer temperature to 145℃ and keep it at that temperature for 80min. Allow it to cool naturally to room temperature and discharge to obtain borosilicate ceramic modified particles.

[0078] By adding flake mica powder and zinc stannate-coated glass powder to a mixer, and then spraying borosilicate modified liquid, the Si-OH and B-OH in the borosilicate modified liquid are adsorbed on the surface of the mica powder or zinc stannate-coated glass powder and condense with their surface hydroxyl groups. As the temperature rises, volatile components such as ethanol and water are gradually removed, and silanol and borosilicate further condense. Further heating and drying increase the degree of condensation and form a more stable borosilicate oxygen network coating layer. Under combustion or high temperature, the low-melting-point glass powder and borosilicate network soften or form a glassy binder phase, while the mica flakes provide a heat-resistant skeleton and layered barrier. The combination of the two can form a relatively continuous and dense inorganic ceramic protective layer on the material surface. This protective layer blocks the transfer of heat, oxygen and combustible pyrolysis gases, thereby increasing the oxygen index and reducing smoke release. Zinc stannate further promotes char formation and smoke suppression, making the combustion residue layer more stable.

[0079] Preparation Example 5

[0080] This preparation example provides a method for preparing borosilicate ceramicized modified particles, specifically including the following steps:

[0081] Step I: Preparation of activated glass powder

[0082] Low-melting-point alkali-free glass powder and 5.5 mol / L sodium hydroxide solution were added to a reaction vessel at a solid-liquid ratio of 1:7.5 and stirred. The reaction vessel was heated to 55°C and stirred for 25 min. The mixture was then filtered, and the filter cake was washed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 65°C and dried to constant weight to obtain activated glass powder.

[0083] Step II: Preparation of zinc stannate-coated glass powder

[0084] Zinc nitrate hexahydrate was dissolved in deionized water to obtain a zinc nitrate solution with a concentration of 0.1 mol / L.

[0085] Sodium stannate trihydrate was dissolved in deionized water to obtain a sodium stannate solution with a concentration of 0.1 mol / L.

[0086] Weigh out 50g of activated glass powder and 500mL of deionized water and add them to the reaction vessel. Stir the reaction vessel and heat it to 70℃. Add 1.1L of zinc nitrate solution and 1L of sodium stannate solution dropwise to the reaction vessel. After the addition is complete, add ammonia water to the reaction vessel to adjust the pH of the system to 8.5. Keep the temperature and stir for 4 hours. Cool the reaction vessel to room temperature and filter. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 115℃ and dry it to constant weight to obtain zinc stannate coated glass powder.

[0087] Step III: Preparation of borosilicate modified solution

[0088] Weigh out 23.6 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol and 100 mL of tetrahydrofuran and add them to a reaction flask under nitrogen protection. Stir the mixture and heat the reaction flask to 45 °C. Add 24.7 g of propyltriethoxysilane isocyanate to the reaction flask and keep the mixture at this temperature for 70 min. Then, evacuate the reaction flask to -0.1 MPa and remove the low-boiling substances by vacuum distillation to obtain triethoxysilane-modified hindered phenol.

[0089] Weigh out 45g of tetraethyl orthosilicate, 11g of trimethyl borate, 13g of phenyltrimethoxysilane, 10g of 3-(methacryloyloxy)propyltrimethoxysilane, 7.5g of triethoxysilane-modified hindered phenol, 600mL of ethanol and 100mL of deionized water, add them to a reaction flask and stir. Add acetic acid to the reaction flask to adjust the pH of the system to 4.5. Pre-hydrolyze at room temperature for 45min to obtain borosilicate modified solution.

[0090] Step IV: Preparation of borosilicate ceramic-modified particles

[0091] Weigh out 1500g of flake mica powder and 600g of zinc stannate-coated glass powder and add them to a high-speed mixer. Set the mixer speed to 17r / min. Spray 300mL of borosilicate modified liquid into the mixer. After spraying, mix for 25min. Raise the mixer temperature to 120℃ and dry for 70min. Then raise the mixer temperature to 150℃ and keep it at that temperature for 90min. Allow it to cool naturally to room temperature and discharge to obtain borosilicate ceramic modified particles.

[0092] Preparation Example 6

[0093] This preparation example provides a method for preparing borosilicate ceramicized modified particles, specifically including the following steps:

[0094] Step I: Preparation of activated glass powder

[0095] Low-melting-point alkali-free glass powder and 6 mol / L sodium hydroxide solution were added to a reaction vessel at a solid-liquid ratio of 1:8 and stirred. The reaction vessel was heated to 60°C and stirred for 30 min. The mixture was then filtered, and the filter cake was washed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 70°C and dried to constant weight to obtain activated glass powder.

[0096] Step II: Preparation of zinc stannate-coated glass powder

[0097] Zinc nitrate hexahydrate was dissolved in deionized water to obtain a zinc nitrate solution with a concentration of 0.1 mol / L.

[0098] Sodium stannate trihydrate was dissolved in deionized water to obtain a sodium stannate solution with a concentration of 0.1 mol / L.

[0099] Weigh out 50g of activated glass powder and 500mL of deionized water and add them to the reaction vessel. Stir the reaction vessel and heat it to 75℃. Add 1.1L of zinc nitrate solution and 1L of sodium stannate solution dropwise to the reaction vessel. After the addition is complete, add ammonia water to the reaction vessel to adjust the pH of the system to 8.8. Keep the temperature and stir for 5h. Cool the reaction vessel to room temperature, filter, wash the filter cake with purified water until neutral, and then dry it. Transfer the filter cake to a drying oven at 120℃ and dry it to constant weight to obtain zinc stannate coated glass powder.

[0100] Step III: Preparation of borosilicate modified solution

[0101] Weigh 23.6 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol and 100 mL of tetrahydrofuran into a reaction flask under nitrogen protection and stir. Heat the reaction flask to 50 °C, add 24.7 g of propyltriethoxysilane isocyanate, keep the reaction at this temperature for 80 min, and then apply a negative pressure of -0.1 MPa to the reaction flask. Remove low-boiling substances by vacuum distillation to obtain triethoxysilane-modified hindered phenol.

[0102] Weigh out 50g of tetraethyl orthosilicate, 12g of trimethyl borate, 14g of phenyltrimethoxysilane, 11g of 3-(methacryloyloxy)propyltrimethoxysilane, 8g of triethoxysilane-modified hindered phenol, 600mL of ethanol and 100mL of deionized water, add them to the reaction flask and stir. Add acetic acid to the reaction flask to adjust the pH of the system to 5. Pre-hydrolyze at room temperature for 50min to obtain borosilicate modified solution.

[0103] Step IV: Preparation of borosilicate ceramic-modified particles

[0104] Weigh out 1500g of flake mica powder and 600g of zinc stannate-coated glass powder and add them to a high-speed mixer. Set the mixer speed to 18r / min. Spray 300mL of borosilicate modified liquid into the mixer. After spraying, mix for 30min. Raise the mixer temperature to 125℃ and dry for 80min. Then raise the mixer temperature to 155℃ and keep it at that temperature for 100min. Allow it to cool naturally to room temperature and discharge to obtain borosilicate ceramic modified particles.

[0105] Example 1

[0106] This embodiment provides a low-smoke halogen-free flame-retardant power cable insulation material, comprising the following components:

[0107] medium density polyethylene 40 copies Commercially available Low-density polyethylene 22 copies Commercially available MAH-g-PE 8 copies Commercially available EVA 38 copies Commercially available Capture-type modified magnesium hydroxide 50 copies Preparation Example 1 borosilicate ceramic modified particles 18 copies Preparation Example 4 dicumyl peroxide 0.9 copies Commercially available Additives 3 copies /

[0108] The additives consist of stearate, antioxidant 1010, antioxidant 168, polyethylene wax, and silicone powder in a weight ratio of 5:2:2:3:2.

[0109] Example 2

[0110] This embodiment provides a low-smoke halogen-free flame-retardant power cable insulation material, comprising the following components:

[0111] medium density polyethylene 45 copies Commercially available Low-density polyethylene 24 copies Commercially available MAH-g-PE 8.5 copies Commercially available EVA 41 copies Commercially available Capture-type modified magnesium hydroxide 55 copies Preparation Example 2 borosilicate ceramic modified particles 20 copies Preparation Example 5 dicumyl peroxide 1.1 copies Commercially available Additives 4 copies /

[0112] The additives consist of stearate, antioxidant 1010, antioxidant 168, polyethylene wax, and silicone powder in a weight ratio of 5:2:2:3:2.

[0113] Example 3

[0114] This embodiment provides a low-smoke halogen-free flame-retardant power cable insulation material, comprising the following components:

[0115] medium density polyethylene 50 copies Commercially available Low-density polyethylene 26 copies Commercially available MAH-g-PE 9 copies Commercially available EVA 46 copies Commercially available Capture-type modified magnesium hydroxide 60 copies Preparation Examples 1-3 borosilicate ceramic modified particles 22 copies Preparation Examples 4-6 dicumyl peroxide 1.3 copies Commercially available Additives 5 copies /

[0116] The additives consist of stearate, antioxidant 1010, antioxidant 168, polyethylene wax, and silicone powder in a weight ratio of 5:2:2:3:2.

[0117] Comparative Example 1

[0118] The difference between this comparative example and Example 3 is that, in the preparation of the captured modified magnesium hydroxide, nano-magnesium hydroxide is used instead of zinc-aluminum coated magnesium hydroxide in step 2.

[0119] Comparative Example 2

[0120] The difference between this comparative example and Example 3 is that the captured modified magnesium hydroxide used is replaced by nano-magnesium hydroxide.

[0121] Comparative Example 3

[0122] The difference between this comparative example and Example 3 is that, in the preparation of the borosilicate ceramicized modified particles, the activated glass powder in step I is used instead of the zinc stannate-coated glass powder in step IV.

[0123] Comparative Example 4

[0124] The difference between this comparative example and Example 3 is that no borosilicate modification solution was added in step IV during the preparation of the borosilicate ceramicized modified particles.

[0125] Performance testing:

[0126] The low-smoke halogen-free flame-retardant power cable insulation materials prepared in Examples 1-3 and Comparative Examples 1-4 were mixed evenly and then added to a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were set to 115°C, 125°C, 135°C, 145°C, 150°C and 150°C respectively, and the die head temperature was 150°C. The mixture was melted and mixed for 40 seconds. The extruded material was used as the outer sheath of the cable to form a sheath layer with a thickness of 2.2 mm. The extruded sheath layer was used as the test sample.

[0127] The volume resistivity of the test sample was determined in accordance with the standard GB / T 31838.2-2019 "Dielectric and resistive properties of solid insulating materials - Part 2: Resistive properties (DC method) - Volume resistivity and volume resistivity".

[0128] The oxygen index of the test sample was determined in accordance with the standard GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test".

[0129] The transmittance of the test sample was determined in accordance with the standard GB / T 17651.2-2021 "Determination of smoke density of cables or optical fibers under specific conditions - Part 2: Test procedures and requirements".

[0130] The tensile strength and elongation at break of the test specimens were determined in accordance with the standard GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods - Thickness and Dimensional Measurements - Mechanical Properties Tests".

[0131] According to standard GB / T 2951.12-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 12: General Test Methods - Thermal Aging Test Method", the test samples were aged in an air oven. The oven temperature was set to 100℃ and the aging time was 36h. After aging, the volume resistivity, oxygen index, light transmittance, tensile strength and elongation at break of the test samples were re-measured.

[0132] The specific test data is shown in Table 1 below.

[0133] Table 1 - Performance test data of the samples before thermal aging

[0134] Example 1 <![CDATA[3.61×10 14 ]]> 35.2 78 15.1 230 Example 2 <![CDATA[3.67×10 14 ]]> 35.7 80 15.8 237 Example 3 <![CDATA[3.58×10 14 ]]> 35.4 77 15.3 233 Comparative Example 1 <![CDATA[3.17×10 14 ]]> 33.4 71.5 14.5 221 Comparative Example 2 <![CDATA[2.71×10 14 ]]> 31.6 64 13.0 185 Comparative Example 3 <![CDATA[2.27×10 14 ]]> 34.2 73 14.9 228 Comparative Example 4 <![CDATA[3.10×10 14 ]]> 33.1 70 14.1 212

[0135] Table 2 - Performance test data of the samples after thermal aging

[0136] Example 1 <![CDATA[2.87×10 14 ]]> 34.3 75 13.9 200 Example 2 <![CDATA[3.01×10 14 ]]> 34.9 77 14.5 207 Example 3 <![CDATA[2.83×10 14 ]]> 34.4 76 14.1 203 Comparative Example 1 <![CDATA[2.58×10 14 ]]> 32.3 68 13.2 190 Comparative Example 2 <![CDATA[2.03×10 14 ]]> 30.2 59 11.1 147 Comparative Example 3 <![CDATA[2.67×10 14 ]]> 33.2 70 13.6 196 Comparative Example 4 <![CDATA[2.46×10 14 ]]> 32.1 67 12.7 182

[0137] Data Analysis:

[0138] Comparative analysis of the data in Tables 1-2 above shows that the volume resistivity of the low-smoke halogen-free flame-retardant power cable insulation material prepared by this invention, before thermal aging, reaches 3.58-3.37×10⁻⁶. 14 The sample exhibits the following properties: Ω·cm, oxygen index of 35.2-35.7%, light transmittance of 77-80%, tensile strength of 15.1-15.8 MPa, and elongation at break of 230-237%. After aging in an air oven at 100℃ for 36 hours, the volume resistivity of the sample reaches 2.83-3.01 × 10⁻⁶. 14The low-smoke halogen-free flame-retardant power cable insulation material of this invention exhibits superior performance compared to the comparative example. This is achieved by using polyethylene and EVA composite resin as a matrix and incorporating trapping modified magnesium hydroxide and borosilicate ceramicized modified particles, thereby improving the material's flame retardancy, low smoke, insulation, and aging resistance. Specifically, the modified magnesium hydroxide can dehydrate and absorb heat, promote the formation of a residual protective layer, and reduce smoke release, while also improving its dispersibility in the resin. The borosilicate ceramicized modified particles can form a dense barrier layer when heated or burned, reducing the transfer of oxygen, heat, and combustible pyrolysis products. The MAH-g-PE, dicumyl peroxide, and silane structures further enhance the bonding between the resin and fillers, reducing the risk of filler agglomeration, interfacial debonding, and aging cracking, thus improving the overall performance of the material.

[0139] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0140] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0141] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low-smoke, halogen-free, flame-retardant power cable insulation material, characterized in that, It comprises the following components by weight: 40-50 parts of medium-density polyethylene, 22-26 parts of low-density polyethylene, 8-9 parts of MAH-g-PE, 38-46 parts of EVA, 50-60 parts of trap-type modified magnesium hydroxide, 18-22 parts of borosilicate ceramic modified particles, 0.9-1.3 parts of initiator, and 3-5 parts of additives; The captured modified magnesium hydroxide is obtained by treating zinc-aluminum coated magnesium hydroxide with vinyltriethoxysilane and 3-aminopropyltriethoxysilane; The borosilicate ceramicized modified particles are obtained by treating flaky mica powder and zinc stannate-coated glass powder with a borosilicate modification solution.

2. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 1, characterized in that, The initiator is dicumyl peroxide, and the additives consist of stearate, antioxidant 1010, antioxidant 168, polyethylene wax and silicone powder in a weight ratio of 5:2:2:3:

2.

3. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 1, characterized in that, The preparation method of the captured modified magnesium hydroxide includes the following steps: zinc-aluminum coated magnesium hydroxide, ethanol aqueous solution, vinyltriethoxysilane and 3-aminopropyltriethoxysilane are mixed and stirred, sodium hydroxide solution is added to the reaction system, the reaction system is heated to 60-70℃, the reaction is kept at the temperature for 4-5 hours, and then post-processed to obtain captured modified magnesium hydroxide.

4. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 3, characterized in that, The ratio of zinc-aluminum coated magnesium hydroxide, ethanol aqueous solution, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, and sodium hydroxide solution is 10g:100mL:1.3-1.5g:0.3-0.4g:5mL. The ethanol aqueous solution is composed of anhydrous ethanol and deionized water in a volume ratio of 7:

3. The concentration of the sodium hydroxide solution is 3-5mol / L.

5. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 3, characterized in that, The preparation method of zinc-aluminum coated magnesium hydroxide is as follows: zinc nitrate, aluminum nitrate and deionized water are mixed and stirred until the system is dissolved. Nano magnesium hydroxide is added to the reaction system. The reaction system is heated to 68-72℃ and stirred for 20-30 min. Sodium phenylphosphinate and boric acid are added to the reaction system. Then sodium hydroxide solution is added to the reaction system to adjust the pH of the system to 9-9.

5. The reaction is kept at the temperature for 3-4 h. After post-treatment, zinc-aluminum coated magnesium hydroxide is obtained.

6. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 5, characterized in that, The ratio of zinc nitrate, aluminum nitrate, deionized water, nano magnesium hydroxide, sodium phenylphosphinate, and boric acid is 1.8g:1g:500mL:60-65g:1.1-1.2g:0.35-0.45g, and the concentration of the sodium hydroxide solution is 3-5mol / L.

7. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 1, characterized in that, The preparation method of the borosilicate ceramic modified particles is as follows: Flake mica powder and zinc stannate-coated glass powder are added to a high-speed mixer, the mixer speed is set to 15-18 r / min, borosilicate modification liquid is sprayed into the mixer, and after spraying, the mixture is mixed for 20-30 min. Then, the mixer temperature is raised to 115-125℃ and dried for 60-80 min. Next, the mixer temperature is raised to 145-155℃ and kept warm for 80-100 min. The mixture is then allowed to cool naturally to room temperature and discharged to obtain borosilicate ceramic modified particles. The weight ratio of the flake mica powder to the zinc stannate-coated glass powder is 5:2, and the liquid-solid ratio of the borosilicate modification liquid to the solid material composed of the flake mica powder and the zinc stannate-coated glass powder is 1:

7.

8. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 7, characterized in that, The borosilicate modified solution is prepared as follows: Tetraethyl orthosilicate, trimethyl borate, phenyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, triethoxysilane-modified hindered phenol, ethanol, and deionized water are mixed and stirred. Acetic acid is added to the reaction system to adjust the pH to 4-5. The mixture is pre-hydrolyzed at room temperature for 40-50 minutes to obtain the borosilicate modified solution. The ratio of tetraethyl orthosilicate, trimethyl borate, phenyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, ethanol, and deionized water is 4-5 g: 1-1.2 g: 1.2-1.4 g: 0.9-1.1 g: 0.7-0.8 g: 60 mL: 10 mL.

9. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 1, characterized in that, The preparation method of the zinc stannate-coated glass powder includes the following steps: A1. Place low-melting-point alkali-free glass powder in a sodium hydroxide solution at a temperature of 50-60℃ and stir to disperse for 20-30 minutes. Then, perform post-treatment to obtain activated glass powder. A2. Mix and stir activated glass powder and deionized water. Heat the reaction system to 65-75℃. Simultaneously add zinc nitrate solution and sodium stannate solution to the reaction system. After the addition is complete, add ammonia water to the reaction system to adjust the pH of the system to 8.2-8.

8. Keep the system warm and stir for 3-5 hours. After post-processing, zinc stannate coated glass powder is obtained.

10. The low-smoke halogen-free flame-retardant power cable insulation material according to claim 9, characterized in that, In step A1, the solid-liquid ratio of the low-melting-point alkali-free glass powder and the sodium hydroxide solution is 1:7-8, and the concentration of the sodium hydroxide solution is 5-6 mol / L. In step A2, the ratio of the activated glass powder, deionized water, zinc nitrate solution, and sodium stannate solution is 5g:50mL:110mL:100mL, the zinc nitrate solution is an aqueous solution of zinc nitrate hexahydrate with a concentration of 0.1mol / L, and the sodium stannate solution is an aqueous solution of sodium stannate trihydrate with a concentration of 0.1mol / L.

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