Insulation protective sleeve material for high-voltage cable and preparation method of insulation protective sleeve material

Abstract

The invention discloses an insulating protective sleeve material for a high-voltage cable and a preparation method thereof, the protective sleeve material is prepared from the following raw materials in parts by weight: 100-120 parts of modified polyethylene, 5-8 parts of modified silicon dioxide, 1-3 parts of a modified additive and 2-5 parts of 2, 2 '-(1, 3-phenylene)-dioxazoline, and the 2, 2'-(1, 3-phenylene)-dioxazoline is added into the raw materials in the melt extrusion process of the raw materials. Oxazoline at one end of (2, 3-phenylene)-dioxazoline reacts with carboxyl on the modified polyethylene, and oxazoline at the other end of (2, 3-phenylene)-dioxazoline reacts with amino on the modified additive or amino on the modified silicon dioxide, so that modified polyethylene molecules and modified additive molecules form dynamic cross-linking, and meanwhile, polysiloxane chain segments are interspersed among molecular networks to form a cross-linked structure. The modified silicon dioxide is added to form a semi-interpenetrating network, so that the mechanical property of the material is greatly improved, and the mechanical strength of the material is remarkably improved on the premise of keeping excellent electrical insulation performance by adding the modified silicon dioxide.

Description

Technical Field

[0001] This invention relates to the field of cable protective sheath material preparation technology, specifically to an insulating protective sheath material for high-voltage cables and its preparation method. Background Technology

[0002] High-voltage cables, as a critical infrastructure for power transmission, play an irreplaceable role in power grid construction, inter-regional grid interconnection, and offshore wind power integration. With the rapid development of new energy power generation and the in-depth advancement of urban power grid transformation, the application demand for high-voltage and ultra-high-voltage cables continues to grow. As the core component ensuring the safe operation of cables, the insulation and protective sheath materials directly affect the reliability and lifespan of the entire power system. Polyolefin materials, represented by low-density polyethylene, linear low-density polyethylene, and their cross-linked products, have become the mainstream matrix materials for high-voltage cable insulation and protective sheaths due to their excellent electrical insulation properties, good processability, and low density and cost. However, their tensile strength, tear resistance, and abrasion resistance are limited, making it difficult to meet the increasingly demanding requirements for mechanical protection in higher voltage levels and complex laying environments (such as direct burial, tunnels, and seabed). Summary of the Invention

[0003] The purpose of this invention is to provide an insulating protective sleeve material for high-voltage cables and its preparation method, which solves the problem of poor mechanical properties of polyethylene used in current protective sleeve materials.

[0004] The objective of this invention can be achieved through the following technical solutions: A method for preparing an insulating protective sheath material for high-voltage cables specifically includes the following steps: Step A1: Disperse silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 300-500 r / min and a temperature of 70-75℃, and react for 3-5 h to obtain aminated silica. Step A2: Mix polyethylene, maleic anhydride and dicumyl peroxide, add to a twin-screw extruder, melt extrude at a speed of 120-150 r / min, and at three-stage and die head temperatures of 170, 180, 200 and 220°C to obtain pretreated polyethylene. Step A3: Immerse the pretreated polyethylene in sodium hydroxide solution and stir for 1-1.5 hours at a speed of 200-300 r / min and a temperature of 90-95℃. Filter to remove the filtrate, then immerse the substrate in hydrochloric acid solution and stir for 0.5-1 hours at a speed of 200-300 r / min and a temperature of 20-25℃ to obtain modified polyethylene. Step A4: Weigh the following raw materials in parts by weight: 100-120 parts of modified polyethylene, 5-8 parts of modified silica, 1-3 parts of modified additives, and 2-5 parts of 2,2'-(1,3-phenylene)-dioxazoline. Add the raw materials to a twin-screw extruder and melt-extrude them at a speed of 120-150 r / min and temperatures of 170, 180, 200, and 220°C for the three sections and the die head to obtain the insulating protective sheath material for high-voltage cables.

[0005] Furthermore, the amount of γ-aminopropyltriethoxysilane used in step A1 is 3% of the mass of silicon dioxide.

[0006] Furthermore, the mass ratio of polyethylene, maleic anhydride, and dicumyl peroxide in step A2 is 100:1.5:0.08.

[0007] Furthermore, the sodium hydroxide solution in step A3 has a mass fraction of 10%, and the hydrochloric acid solution has a mass fraction of 10%.

[0008] Furthermore, the modified additive is prepared by the following steps: Step B1: Maleic anhydride and acetone are mixed and purged with nitrogen. Under nitrogen protection, the mixture is stirred and 4,4'-diaminodiphenyl disulfide is added. After reacting for 2-3 hours, sodium acetate and acetic anhydride are added, and the mixture is heated to 75-80℃ and refluxed for 8-10 hours to obtain an intermediate. Furanic acid, the intermediate, and DMF are mixed and purged with nitrogen. Under nitrogen protection, the mixture is reacted for 8-10 hours at a speed of 150-200 r / min and a temperature of 70-80℃ to obtain the modified monomer. Step B2: Mix octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(aminopropane)tetramethyldisiloxane and tetrahydrofuran, purge with nitrogen, and react for 10-15 h at a speed of 150-200 r / min and a temperature of 90-95℃. Then raise the temperature to 100-105℃ and continue the reaction for 2-3 h to obtain aminopolysiloxane. Step B3: Mix lithium trimethylsilanolate and tetrahydrofuran, purge with nitrogen, stir and add hexamethylcyclotrisiloxane at 150-200 r / min and 0℃, heat to 20-25℃ and react for 20-24 h, then add vinyltrichlorosilane and continue the reaction for 2-3 h to obtain branched polysiloxane; Step B4: Mix the aminated polysiloxane, branched polysiloxane, caster catalyst, and xylene, and purge under nitrogen protection. React at 150-200 r / min and 80-85℃ for 6-8 hours to obtain the modified polysiloxane. Mix the modified monomer, 4-dimethylaminopyridine, and xylene, and purge under nitrogen protection. Stir and add the modified polysiloxane and dicyclohexylcarbodiimide at 200-300 r / min and 0-5℃ for 3-5 hours to obtain the modified additive.

[0009] Furthermore, the molar ratio of maleic anhydride, 4,4'-diaminodiphenyl disulfide, sodium acetate, and acetic anhydride in step B1 is 16:8:8:9, and the molar ratio of furanoic acid and the intermediate is 1:2.

[0010] Furthermore, the molar ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, and 1,3-bis(aminopropane)tetramethyldisilether in step B2 is 1:0.2:1.5:1.

[0011] Furthermore, the molar ratio of Si-Cl bonds on lithium trimethylsilanolate, hexamethylcyclotrisiloxane, and vinyltrichlorosilane in step B3 is 1:5:1.

[0012] Furthermore, in step B4, the molar ratio of Si-H on the aminated polysiloxane to the branched polysiloxane is 1:1, the amount of cassette catalyst is 0.01% of the mass of the branched polysiloxane, and the ratio of the amount of modified monomer, 4-dimethylaminopyridine, modified polysiloxane and dicyclohexylcarbodiimide is 1:0.5:2:2.1.

[0013] The beneficial effects of the present invention are as follows: The present invention discloses an insulating protective sheath material for high-voltage cables, comprising the following raw materials: modified polyethylene, modified silica, modified additives and 2,2'-(1,3-phenylene)-dioxazoline. The modified polyethylene is prepared by treating polyethylene with maleic anhydride to obtain pretreated polyethylene. The pretreated polyethylene is then treated with sodium hydroxide solution to convert the anhydride on the pretreated polyethylene into sodium carboxylate. Finally, it is acidified with hydrochloric acid solution to obtain modified polyethylene.

[0014] Modified silica is prepared by treating silica as a raw material with γ-aminopropyltriethoxysilane to graft amino groups onto the surface.

[0015] The modified additive uses 4,4'-diaminodiphenyl disulfide as a raw material and treats it with maleic anhydride, causing the maleic anhydride and the amino group on 4,4'-diaminodiphenyl disulfide to react and form a maleimide structure, thus obtaining an intermediate. The intermediate is then reacted with furanoic acid, causing the maleimide on the intermediate to react with the furanyl group (DA) on the furanoic acid, thus obtaining a modified monomer. Octamethylcyclotetrasiloxane and tetramethylcyclotetrasiloxane are then ring-opened polymerized and capped with 1,3-bis(aminopropyl)tetramethyldisiloxane to obtain an aminopolysiloxane. Trimethylsilanol is then used... Lithium is used as an initiator and hexamethylcyclotrisiloxane is used as a polymerization monomer to form a polysiloxane with lithium silanolate at one end. Vinyltrichlorosilane is added, causing the Si-Cl bond on vinyltrichlorosilane to react with the lithium silanolate to obtain a branched polysiloxane. The amino polysiloxane is reacted with the branched polysiloxane, causing the Si-H bond on the amino polysiloxane to react with the double bond on the branched polysiloxane to obtain a modified polysiloxane. The modified polysiloxane is reacted with a modified monomer, causing the amino group on the modified polysiloxane and the carboxyl group on the modified monomer to undergo a dehydration reaction to obtain a modified additive.

[0016] During the melt extrusion process of the raw material, the oxazoline at one end of 2,2'-(1,3-phenylene)-dioxazoline reacts with the carboxyl group on the modified polyethylene, and the oxazoline at the other end reacts with the amino group on the modified additive or the amino group on the modified silica. This results in dynamic cross-linking between the modified polyethylene molecules and the modified additive molecules. At the same time, polysiloxane segments are interspersed between the molecular networks to form a semi-interpenetrating network, which greatly improves the mechanical properties of the material. The addition of modified silica significantly improves the mechanical strength of the material while maintaining excellent electrical insulation properties. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: A method for preparing an insulating protective sheath material for high-voltage cables, specifically including the following steps: Step A1: Disperse silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 300 r / min and a temperature of 70℃, and react for 3 h to obtain aminated silica. Step A2: Mix polyethylene, maleic anhydride and dicumyl peroxide, add to a twin-screw extruder, melt extrude at a speed of 120 r / min and three-stage and die head temperatures of 170, 180, 200 and 220°C to obtain pretreated polyethylene. Step A3: Immerse the pretreated polyethylene in sodium hydroxide solution and stir for 1 hour at 200 r / min and 90°C. Filter to remove the filtrate and immerse the substrate in hydrochloric acid solution and stir for 0.5 hours at 200 r / min and 20°C to obtain modified polyethylene. Step A4: Weigh the following raw materials in parts by weight: 100 parts modified polyethylene, 5 parts modified silica, 1 part modified additive, and 2 parts 2,2'-(1,3-phenylene)-dioxazoline. Add the raw materials to a twin-screw extruder and melt-extrude them at a speed of 120 r / min and three-stage and die head temperatures of 170, 180, 200, and 220°C to obtain the insulating protective sheath material for high-voltage cables.

[0019] The amount of γ-aminopropyltriethoxysilane used in step A1 is 3% of the mass of silicon dioxide.

[0020] The mass ratio of polyethylene, maleic anhydride and dicumyl peroxide mentioned in step A2 is 100:1.5:0.08, and the polyethylene is low-density polyethylene with a density of MI=1.5g / 10min.

[0021] The sodium hydroxide solution in step A3 has a mass fraction of 10%, and the hydrochloric acid solution has a mass fraction of 10%.

[0022] The modified additive is prepared by the following steps: Step B1: Maleic anhydride and acetone were mixed and purged with nitrogen. Under nitrogen protection, the mixture was stirred and 4,4'-diaminodiphenyl disulfide was added. After reacting for 2 hours, sodium acetate and acetic anhydride were added, the temperature was raised to 75°C, and the mixture was refluxed for 8 hours to obtain an intermediate. Furanic acid, the intermediate, and DMF were mixed and purged with nitrogen. Under nitrogen protection, the mixture was reacted for 8 hours at a speed of 150 r / min and a temperature of 70°C to obtain the modified monomer. Step B2: Octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(aminopropane)tetramethyldisiloxane and tetrahydrofuran are mixed and purged with nitrogen. The mixture is reacted at 150 r / min and 90 °C for 10 h. The temperature is then raised to 100 °C and the reaction is continued for 2 h to obtain aminopolysiloxane. Step B3: Mix lithium trimethylsilanolate and tetrahydrofuran, purge with nitrogen, stir and add hexamethylcyclotrisiloxane at 150 r / min and 0 °C, heat to 20 °C and react for 20 h, then add vinyltrichlorosilane and continue the reaction for 2 h to obtain branched polysiloxane. Step B4: Mix the aminated polysiloxane, branched polysiloxane, caster catalyst, and xylene, and purge with nitrogen. React at 150 r / min and 80 °C for 6 h to obtain the modified polysiloxane. Mix the modified monomer, 4-dimethylaminopyridine, and xylene, and purge with nitrogen. Stir and add the modified polysiloxane and dicyclohexylcarbodiimide at 200 r / min and 0 °C, and react for 3 h to obtain the modified additive.

[0023] The molar ratio of maleic anhydride, 4,4'-diaminodiphenyl disulfide, sodium acetate and acetic anhydride in step B1 is 16:8:8:9, and the molar ratio of furanoic acid and intermediate is 1:2.

[0024] The molar ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, and 1,3-bis(aminopropane)tetramethyldisilether in step B2 is 1:0.2:1.5:1.

[0025] The molar ratio of Si-Cl bonds on lithium trimethylsilanolate, hexamethylcyclotrisiloxane and vinyltrichlorosilane in step B3 is 1:5:1.

[0026] In step B4, the molar ratio of Si-H on the aminated polysiloxane to the branched polysiloxane is 1:1, the amount of cassette catalyst is 0.01% of the mass of the branched polysiloxane, and the ratio of modified monomer, 4-dimethylaminopyridine, modified polysiloxane and dicyclohexylcarbodiimide is 1:0.5:2:2.1.

[0027] Example 2: A method for preparing an insulating protective sheath material for high-voltage cables, specifically including the following steps: Step A1: Disperse silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 300 r / min and a temperature of 75℃, and react for 4 h to obtain aminated silica. Step A2: Mix polyethylene, maleic anhydride and dicumyl peroxide, add to a twin-screw extruder, melt extrude at a speed of 120 r / min and three-stage and die head temperatures of 170, 180, 200 and 220°C to obtain pretreated polyethylene. Step A3: Immerse the pretreated polyethylene in sodium hydroxide solution and stir for 1.5 h at a speed of 300 r / min and a temperature of 90 °C. Filter to remove the filtrate and immerse the substrate in hydrochloric acid solution and stir for 0.5 h at a speed of 200 r / min and a temperature of 25 °C to obtain modified polyethylene. Step A4: Weigh the following raw materials in parts by weight: 110 parts modified polyethylene, 6.5 parts modified silica, 2 parts modified additives, and 3.5 parts 2,2'-(1,3-phenylene)-dioxazoline. Add the raw materials to a twin-screw extruder and melt-extrude them at a speed of 120 r / min and three-stage and die head temperatures of 170, 180, 200, and 220°C to obtain the insulating protective sheath material for high-voltage cables.

[0028] The amount of γ-aminopropyltriethoxysilane used in step A1 is 3% of the mass of silicon dioxide.

[0029] The mass ratio of polyethylene, maleic anhydride and dicumyl peroxide mentioned in step A2 is 100:1.5:0.08, and the polyethylene is low-density polyethylene with a density of MI=1.5g / 10min.

[0030] The sodium hydroxide solution in step A3 has a mass fraction of 10%, and the hydrochloric acid solution has a mass fraction of 10%.

[0031] The modified additive is prepared by the following steps: Step B1: Maleic anhydride and acetone were mixed and purged with nitrogen. Under nitrogen protection, the mixture was stirred and 4,4'-diaminodiphenyl disulfide was added. After reacting for 3 hours, sodium acetate and acetic anhydride were added, the temperature was raised to 75°C, and the mixture was refluxed for 9 hours to obtain an intermediate. Furanic acid, the intermediate, and DMF were mixed and purged with nitrogen. Under nitrogen protection, the mixture was reacted for 9 hours at a speed of 200 r / min and a temperature of 75°C to obtain the modified monomer. Step B2: Octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(aminopropane)tetramethyldisiloxane and tetrahydrofuran are mixed and purged with nitrogen. The mixture is reacted at 200 r / min and 90 °C for 15 h. The temperature is then raised to 100 °C and the reaction is continued for 3 h to obtain aminopolysiloxane. Step B3: Mix lithium trimethylsilanolate and tetrahydrofuran, purge with nitrogen, stir and add hexamethylcyclotrisiloxane at 150 r / min and 0 °C, heat to 25 °C and react for 20 h, then add vinyltrichlorosilane and continue the reaction for 3 h to obtain branched polysiloxane. Step B4: Mix the aminated polysiloxane, branched polysiloxane, caster catalyst, and xylene, and purge with nitrogen. React at 150 r / min and 85 °C for 6 h to obtain the modified polysiloxane. Mix the modified monomer, 4-dimethylaminopyridine, and xylene, and purge with nitrogen. Stir and add the modified polysiloxane and dicyclohexylcarbodiimide at 300 r / min and 0 °C, and react for 5 h to obtain the modified additive.

[0032] The molar ratio of maleic anhydride, 4,4'-diaminodiphenyl disulfide, sodium acetate and acetic anhydride in step B1 is 16:8:8:9, and the molar ratio of furanoic acid and intermediate is 1:2.

[0033] The molar ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, and 1,3-bis(aminopropane)tetramethyldisilether in step B2 is 1:0.2:1.5:1.

[0034] The molar ratio of Si-Cl bonds on lithium trimethylsilanolate, hexamethylcyclotrisiloxane and vinyltrichlorosilane in step B3 is 1:5:1.

[0035] In step B4, the molar ratio of Si-H on the aminated polysiloxane to the branched polysiloxane is 1:1, the amount of cassette catalyst is 0.01% of the mass of the branched polysiloxane, and the ratio of modified monomer, 4-dimethylaminopyridine, modified polysiloxane and dicyclohexylcarbodiimide is 1:0.5:2:2.1.

[0036] Example 3: A method for preparing an insulating protective sheath material for high-voltage cables, specifically including the following steps: Step A1: Disperse silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 500 r / min and a temperature of 75℃, and react for 5 h to obtain aminated silica. Step A2: Mix polyethylene, maleic anhydride and dicumyl peroxide, add to a twin-screw extruder, melt extrude at a speed of 150 r / min and three-stage and die head temperatures of 170, 180, 200 and 220°C to obtain pretreated polyethylene. Step A3: The pretreated polyethylene was immersed in sodium hydroxide solution and stirred for 1.5 h at a speed of 300 r / min and a temperature of 95 °C. The filtrate was then removed by filtration. The substrate was then immersed in hydrochloric acid solution and stirred for 1 h at a speed of 300 r / min and a temperature of 25 °C to obtain modified polyethylene. Step A4: Weigh the following raw materials in parts by weight: 120 parts modified polyethylene, 8 parts modified silica, 3 parts modified additives, and 5 parts 2,2'-(1,3-phenylene)-dioxazoline. Add the raw materials to a twin-screw extruder and melt-extrude them at a speed of 150 r / min and three-stage and die head temperatures of 170, 180, 200, and 220°C to obtain the insulating protective sheath material for high-voltage cables.

[0037] The amount of γ-aminopropyltriethoxysilane used in step A1 is 3% of the mass of silicon dioxide.

[0038] The mass ratio of polyethylene, maleic anhydride and dicumyl peroxide mentioned in step A2 is 100:1.5:0.08, and the polyethylene is low-density polyethylene with a density of MI=1.5g / 10min.

[0039] The sodium hydroxide solution in step A3 has a mass fraction of 10%, and the hydrochloric acid solution has a mass fraction of 10%.

[0040] The modified additive is prepared by the following steps: Step B1: Maleic anhydride and acetone were mixed and purged with nitrogen. Under nitrogen protection, the mixture was stirred at 150 r / min and 0 °C, and 4,4'-diaminodiphenyl disulfide was added. After reacting for 3 h, sodium acetate and acetic anhydride were added, the temperature was raised to 80 °C, and the mixture was refluxed for 10 h to obtain an intermediate. Furanic acid, the intermediate, and DMF were mixed and purged with nitrogen. Under nitrogen protection, the mixture was reacted at 200 r / min and 80 °C for 10 h to obtain the modified monomer. Step B2: Octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(aminopropane)tetramethyldisiloxane and tetrahydrofuran are mixed and purged with nitrogen. The mixture is reacted at 200 r / min and 95 °C for 15 h. The temperature is then raised to 105 °C and the reaction is continued for 3 h to obtain aminopolysiloxane. Step B3: Mix lithium trimethylsilanolate and tetrahydrofuran, purge with nitrogen, stir and add hexamethylcyclotrisiloxane at 200 r / min and 0 °C, heat to 25 °C and react for 24 h, then add vinyltrichlorosilane and continue the reaction for 3 h to obtain branched polysiloxane. Step B4: Mix the aminated polysiloxane, branched polysiloxane, caster catalyst, and xylene, and purge with nitrogen. React at 200 r / min and 85°C for 8 h to obtain the modified polysiloxane. Mix the modified monomer, 4-dimethylaminopyridine, and xylene, and purge with nitrogen. Stir and add the modified polysiloxane and dicyclohexylcarbodiimide at 300 r / min and 5°C, and react for 5 h to obtain the modified additive.

[0041] The molar ratio of maleic anhydride, 4,4'-diaminodiphenyl disulfide, sodium acetate and acetic anhydride in step B1 is 16:8:8:9, and the molar ratio of furanoic acid and intermediate is 1:2.

[0042] The molar ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, and 1,3-bis(aminopropane)tetramethyldisilether in step B2 is 1:0.2:1.5:1.

[0043] The molar ratio of Si-Cl bonds on lithium trimethylsilanolate, hexamethylcyclotrisiloxane and vinyltrichlorosilane in step B3 is 1:5:1.

[0044] In step B4, the molar ratio of Si-H on the aminated polysiloxane to the branched polysiloxane is 1:1, the amount of cassette catalyst is 0.01% of the mass of the branched polysiloxane, and the ratio of modified monomer, 4-dimethylaminopyridine, modified polysiloxane and dicyclohexylcarbodiimide is 1:0.5:2:2.1.

[0045] Comparative Example 1: This comparative example uses silicon dioxide instead of modified silicon dioxide, but the other steps are the same as in Example 1.

[0046] Comparative Example 2: This comparative example uses modified polysiloxane instead of the modifying additives, while the remaining steps are the same as in Example 1.

[0047] Comparative Example 3: This comparative example uses ethylenediamine instead of modified polysiloxane, while the other steps are the same as in Example 1.

[0048] The protective sleeve materials obtained in Examples 1-3 and Comparative Examples 1-3 were made into Type 1A specimens according to GB / T1040.1-2018 standard, and the tensile strength was tested at a tensile rate of 50 mm / min. According to GB / T1043.1-2008, Type 1 specimens were made and the impact strength was tested. The test results are shown in Table 1 below.

[0049] Table 1

[0050] As shown in Table 1, this application possesses excellent mechanical properties. The above description is merely illustrative and explanatory of the concept of this invention. Various modifications, additions, or similar substitutions made by those skilled in the art to the described specific embodiments, as long as they do not deviate from the inventive concept or exceed the scope defined in these claims, should fall within the protection scope of this invention.

Claims

1. A method for preparing an insulating protective sheath material for high-voltage cables, characterized in that: Specifically, the steps include the following: Step A1: Disperse silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water to react and obtain aminated silica; Step A2: Mix polyethylene, maleic anhydride and dicumyl peroxide, add to a twin-screw extruder, melt extrude to obtain pretreated polyethylene; Step A3: Immerse the pretreated polyethylene in sodium hydroxide solution, stir, filter to remove the filtrate, immerse the substrate in hydrochloric acid solution, stir, and obtain modified polyethylene. Step A4: Weigh the following raw materials in parts by weight: 100-120 parts of modified polyethylene, 5-8 parts of modified silica, 1-3 parts of modified additives and 2-5 parts of 2,2'-(1,3-phenylene)-dioxazoline. Add the raw materials to a twin-screw extruder and melt-extrude to obtain the insulating protective sheath material for high-voltage cables.

2. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 1, characterized in that: The amount of γ-aminopropyltriethoxysilane used in step A1 is 3% of the mass of silicon dioxide.

3. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 1, characterized in that: The mass ratio of polyethylene, maleic anhydride and dicumyl peroxide mentioned in step A2 is 100:1.5:0.

08.

4. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 1, characterized in that: The sodium hydroxide solution in step A3 has a mass fraction of 10%, and the hydrochloric acid solution has a mass fraction of 10%.

5. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 1, characterized in that: The modified additive is prepared by the following steps: Step B1: Mix maleic anhydride and acetone, purge with nitrogen for protection, stir and add 4,4'-diaminodiphenyl disulfide, react, then add sodium acetate and acetic anhydride, reflux for 8-10 h to obtain an intermediate. Mix furanyl carboxylic acid, the intermediate and DMF, purge with nitrogen for protection, react to obtain the modified monomer. Step B2: Mix octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,3-bis(aminopropane)tetramethyldisiloxane and tetrahydrofuran, and carry out the reaction under nitrogen protection to obtain aminopolysiloxane. Step B3: Mix lithium trimethylsilanolate and tetrahydrofuran, purge with nitrogen, stir and add hexamethylcyclotrisiloxane, heat and react, then add vinyltrichlorosilane and continue the reaction to obtain branched polysiloxane. Step B4: Mix the aminated polysiloxane, branched polysiloxane, chloroplatinic acid and xylene, and react under nitrogen protection to obtain modified polysiloxane. Mix the modified monomer, 4-dimethylaminopyridine and xylene, and react under nitrogen protection. Stir and add the modified polysiloxane and dicyclohexylcarbodiimide to obtain modified additive.

6. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 5, characterized in that: The molar ratio of maleic anhydride, 4,4'-diaminodiphenyl disulfide, sodium acetate and acetic anhydride in step B1 is 16:8:8:9, and the molar ratio of furanoic acid and intermediate is 1:

2.

7. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 5, characterized in that: The molar ratio of octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethylammonium hydroxide, and 1,3-bis(aminopropane)tetramethyldisilether in step B2 is 1:0.2:1.5:

1.

8. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 5, characterized in that: The molar ratio of Si-Cl bonds on lithium trimethylsilanolate, hexamethylcyclotrisiloxane and vinyltrichlorosilane in step B3 is 1:5:

1.

9. The method for preparing the insulating protective sheath material for high-voltage cables according to claim 5, characterized in that: In step B4, the molar ratio of Si-H on the aminated polysiloxane to the branched polysiloxane is 1:1, the amount of cassette catalyst is 0.01% of the mass of the branched polysiloxane, and the ratio of modified monomer, 4-dimethylaminopyridine, modified polysiloxane and dicyclohexylcarbodiimide is 1:0.5:2:2.

1.

10. An insulating protective sleeve material for high-voltage cables, characterized in that: Prepared according to any one of the preparation methods described in claims 1-9.

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