Halogen-free flame-retardant semi-conductive shielding cable material

Abstract

The invention provides a halogen-free flame-retardant semiconductive shielding cable material, and belongs to the technical field of cable material preparation. The cable material is prepared from the following raw materials in parts by weight: 40 to 55 parts of low-density polyethylene, 75 to 92 parts of ethylene-vinyl acetate copolymer, 5 to 85 parts of mesoporous SiO2 loaded with a conductive agent and a flame retardant, 2 to 4 parts of tetra [beta-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, 2 to 6 parts of zinc stearate and 5 to 8 parts of epoxidized soybean oil. The mesoporous SiO loaded with the conductive agent and the flame retardant is prepared from the following raw materials: single-walled carbon nanotubes, graphene nanosheets, conductive carbon black, sodium dodecyl benzene sulfonate, melamine phosphate, zinc borate and modified mesoporous SiO; the modified mesoporous SiO is characterized in that gamma-aminoethyl aminopropyl trimethoxy silane and alkyl glycoside are used as modifiers. The flame-retardant cable material is good in flame retardance, high in strength and relatively good in electrical property.

Description

Technical Field

[0001] The present invention relates to the technical field of cable material preparation, and particularly relates to a halogen-free flame-retardant semi-conductive shielding cable material. Background Art

[0002] Common base materials for the semi-conductive shielding layer of flame-retardant cables include polyethylene (PE), cross-linked polyethylene (XLPE), ethylene propylene rubber (EPR), etc. Among them, polyethylene has good electrical insulation performance and processing performance, and is suitable for medium and high voltage cables.

[0003] Existing semi-conductive shielding layer materials for flame-retardant cables generally add bromine-based and chlorine-based halogen-containing flame retardants on the basis of the base material. Although they have good flame retardant effects, they will release toxic and corrosive gases such as HBr at high temperatures, which will cause harm to the environment and human health. At present, some technicians are also trying to use halogen-free flame retardant materials such as aluminum hydroxide and magnesium hydroxide to replace halogen-containing flame retardants. However, such flame retardants need to be added in large amounts to meet the flame retardant requirements, resulting in a relatively high volume resistivity of the cable material, and it is difficult to meet the requirements of the semi-conductive shielding layer of medium and high voltage cables for low volume resistivity. In addition, if good electrical conductivity of the semi-conductive shielding layer is to be achieved, 36-50 wt% of carbon black is usually added when producing shielding cable materials according to traditional processes. However, a high proportion of carbon black will make the processing performance of the cable material poor, the surface rough, and prone to partial discharge.

[0004] In summary, it can be seen that the current semi-conductive shielding layer of flame-retardant cables still has problems such as poor environmental protection, insufficient mechanical properties, and high surface roughness. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a halogen-free flame-retardant semi-conductive shielding cable material, and achieves the following invention objectives: to prepare a semi-conductive shielding cable material that does not contain halogens, has strong flame retardancy, low surface roughness, and good mechanical properties.

[0006] In order to achieve the above object, the following technical solutions are adopted: A halogen-free flame-retardant semi-conductive shielding cable material, the raw materials of which include a base material and auxiliary materials; the base material includes low-density polyethylene and ethylene-vinyl acetate copolymer; the auxiliary materials include mesoporous SiO2 loaded with a conductive agent and a flame retardant, pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], zinc stearate, and epoxidized soybean oil.

[0007] The weight part ratio of the above raw materials is: 40-55 parts of low-density polyethylene, 75-92 parts of ethylene-vinyl acetate copolymer, 75-85 parts of mesoporous SiO2 loaded with a conductive agent and a flame retardant, 2-4 parts of pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-6 parts of zinc stearate, and 5-8 parts of epoxidized soybean oil; The mesoporous SiO2 loaded with a conductive agent and a flame retardant is made from the following raw materials: single-walled carbon nanotubes, graphene nanosheets, conductive carbon black, sodium dodecylbenzenesulfonate, melamine phosphate, zinc borate, and modified mesoporous SiO2; The modified mesoporous SiO2 uses γ-aminopropyltriethoxysilane and alkyl polyglycoside as modifiers.

[0008] A preparation method of a halogen-free flame-retardant semi-conductive shielding cable compound includes steps of preparing modified mesoporous SiO2, loading a conductive agent and a flame retardant, and melt-blending to prepare the cable compound; For the preparation of the modified mesoporous SiO2, by weight, the raw materials include: 45-50 parts of tetraethyl orthosilicate, 2-5 parts of γ-aminopropyltriethoxysilane, 5-7 parts of glacial acetic acid, 150-160 parts of ethanol, 50-60 parts of deionized water, and 3-5 parts of alkyl polyglycoside.

[0009] For the preparation of the modified mesoporous SiO2: Mix and stir tetraethyl orthosilicate, ethanol, glacial acetic acid, and deionized water, and hydrolyze to generate a uniformly transparent SiO2 sol; Add γ-aminopropyltriethoxysilane to the SiO2 sol, and perform ultrasonic treatment at a frequency of 26 kHz under the condition of 70-90 °C for 2-4 h; Then add alkyl polyglycoside, continue ultrasonic treatment for 1-2 h and then centrifuge to retain the solid phase; Calcinate the solid phase to obtain the modified mesoporous SiO2.

[0010] The calcination is carried out at 500-600 °C for 3-6 h.

[0011] For the loading of the conductive agent and the flame retardant, by weight, the raw materials include: 2-4 parts of single-walled carbon nanotubes, 2-5 parts of graphene nanosheets, 4-6 parts of conductive carbon black, 0.02-0.05 parts of sodium dodecylbenzenesulfonate, 60-70 parts of modified mesoporous SiO2, 10-15 parts of melamine phosphate, and 5-9 parts of zinc borate.

[0012] For the loading of the conductive agent and the flame retardant: Put single-walled carbon nanotubes, graphene nanosheets, conductive carbon black, and sodium dodecylbenzenesulfonate into N,N-dimethylformamide, and perform ultrasonic treatment at a frequency of 32 kHz for 2-3 h; Then add modified mesoporous SiO2, melamine phosphate, and zinc borate and stir to obtain a mixed solution; Ultrasonically disperse the mixed solution at 32 kHz for 1-2 h, filter the mixed solution after the ultrasonic dispersion ends, and retain the solid; The solid is vacuum-dried to obtain the mesoporous SiO2 loaded with the conductive agent and the flame retardant.

[0013] The cable material is prepared by melt blending. The raw materials, by weight, include: 40 - 55 parts of low - density polyethylene, 75 - 92 parts of ethylene - vinyl acetate copolymer, 75 - 85 parts of mesoporous SiO₂ loaded with conductive agent and flame retardant, 2 - 4 parts of pentaerythritol tetra[β - (3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionate], 2 - 6 parts of zinc stearate, and 5 - 8 parts of epoxidized soybean oil.

[0014] The cable material is prepared by melt blending: The mixture of low - density polyethylene, ethylene - vinyl acetate copolymer, mesoporous SiO₂ loaded with conductive agent and flame retardant, pentaerythritol tetra[β - (3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionate], zinc stearate, and epoxidized soybean oil is added to a twin - screw extruder for melt extrusion to obtain a halogen - free flame - retardant semi - conductive shielding cable material.

[0015] The low - density polyethylene (LDPE) has a density of 0.910 - 0.925 g / cm³; The ethylene - vinyl acetate copolymer (EVA) has a density of 0.91 - 0.94 g / cm³ and a vinyl acetate content of 30 - 40 wt%. Beneficial effects

[0016] A halogen - free flame - retardant semi - conductive shielding cable material provided by the present invention, through innovation of flame - retardant fillers and conductive fillers, has good flame retardancy, does not contain halogens, has high strength, low volume resistivity and surface roughness, and has good electrical properties. Specific embodiments

[0017] To make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention.

[0018] Example 1 A halogen - free flame - retardant semi - conductive shielding cable material A preparation method of a halogen - free flame - retardant semi - conductive shielding cable material: Step 1. Prepare modified mesoporous SiO₂ The raw materials, by weight, include: 45 parts of tetraethyl orthosilicate (TEOS), 2 parts of γ - aminoethylaminopropyltrimethoxysilane (KH - 792), 5 parts of glacial acetic acid, 155 parts of ethanol, 52 parts of deionized water, and 3 parts of alkyl polyglycoside (APG).

[0019] Mix TEOS, ethanol, glacial acetic acid and deionized water and stir. Hydrolyze to generate a uniform and transparent SiO2 sol. Add KH-792 to the SiO2 sol and carry out ultrasonic reaction at 75 °C and 26 kHz for 2.5 h. After the ultrasonic reaction, add APG and continue ultrasonic treatment for 1 h. Centrifuge the ultrasonically treated material and retain the solid phase. Calcinate the solid phase at 500 °C for 6 h to obtain modified mesoporous SiO2.

[0020] Step 2: Load conductive agent and flame retardant By weight, the raw materials include: 2 parts of single-walled carbon nanotubes (SWCNTs), 4 parts of graphene nanosheets (GNSs), 6 parts of conductive carbon black, 0.04 part of sodium dodecylbenzenesulfonate (SDBS), 68 parts of modified mesoporous SiO2, 15 parts of melamine phosphate (MPP), and 9 parts of zinc borate (ZB).

[0021] Put SWCNTs, GNSs, conductive carbon black, and SDBS into N,N-dimethylformamide (DMF), carry out ultrasonic treatment at 32 kHz for 3 h, then add modified mesoporous SiO2, MPP, and ZB and stir for 30 min to obtain a mixed solution. Ultrasonically disperse the mixed solution at 32 kHz for 2 h. After the ultrasonic dispersion, filter the mixed solution, retain the solid, and vacuum dry the solid at 80 °C for 7 h to obtain mesoporous SiO2 loaded with conductive agent and flame retardant.

[0022] DMF is a solvent and does not participate in the reaction. The dosage is based on the ability to dissolve the solute.

[0023] Step 3: Melt-blend to prepare cable material By weight, the raw materials include: 48 parts of low-density polyethylene (LDPE), 90 parts of ethylene-vinyl acetate copolymer (EVA), 83 parts of mesoporous SiO2 loaded with conductive agent and flame retardant, 2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2 parts of zinc stearate, and 7 parts of epoxidized soybean oil.

[0024] First, add LDPE, EVA, mesoporous SiO2 loaded with conductive agent and flame retardant, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], zinc stearate, and epoxidized soybean oil to a high-speed mixer and mix for 15 min. Then add the mixed material to a twin-screw extruder for melt extrusion to obtain a halogen-free flame-retardant semi-conductive shielding cable material. Temperature control of the twin-screw extruder: feeding zone 150 °C, melting zone 165 °C, mixing zone 180 °C, die head zone 175 °C.

[0025] Example 2 A halogen-free flame-retardant semi-conductive shielding cable material A preparation method of a halogen-free flame-retardant semi-conductive shielding cable material: Step 1: Prepare modified mesoporous SiO2 By weight, the raw materials include: 50 parts of tetraethyl orthosilicate (TEOS), 4 parts of γ-aminopropyltriethoxysilane (KH-792), 6 parts of glacial acetic acid, 160 parts of ethanol, 60 parts of deionized water, and 5 parts of alkyl polyglycoside (APG).

[0026] Mix and stir TEOS, ethanol, glacial acetic acid and deionized water, and hydrolyze to generate a uniform and transparent SiO2 sol. Add KH-792 to the SiO2 sol, and carry out ultrasonic reaction at 70 °C and 26 kHz for 4 h; after the ultrasonic reaction, add APG and continue ultrasonic treatment for 1 h; centrifuge the ultrasonically treated material and retain the solid phase; calcine the solid phase at 550 °C for 4 h to obtain modified mesoporous SiO2.

[0027] Step 2: Load conductive agent and flame retardant By weight, the raw materials include: 4 parts of single-walled carbon nanotubes (SWCNTs), 5 parts of graphene nanosheets (GNSs), 5 parts of conductive carbon black, 0.05 part of sodium dodecylbenzenesulfonate (SDBS), 70 parts of modified mesoporous SiO2, 12 parts of melamine phosphate (MPP), and 6 parts of zinc borate (ZB).

[0028] Put SWCNTs, GNSs, conductive carbon black, and SDBS into DMF, carry out ultrasonic treatment at 32 kHz for 2 h, then add modified mesoporous SiO2, MPP, and ZB and stir for 30 min to obtain a mixed solution; ultrasonically disperse the mixed solution at 32 kHz for 1 h; after the ultrasonic dispersion, filter the mixed solution, retain the solid, and vacuum dry the solid at 80 °C for 8 h to obtain mesoporous SiO2 loaded with conductive agent and flame retardant.

[0029] DMF is used as a solvent and does not participate in the reaction. The dosage is based on the ability to dissolve the solute.

[0030] Step 3: Melt blending to prepare cable material By weight, the raw materials include: 40 parts of low-density polyethylene (LDPE), 92 parts of ethylene-vinyl acetate copolymer (EVA), 85 parts of mesoporous SiO2 loaded with conductive agent and flame retardant, 3 parts of pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 4 parts of zinc stearate, and 5 parts of epoxidized soybean oil.

[0031] First, LDPE, EVA, mesoporous SiO2 loaded with conductive agent and flame retardant, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], zinc stearate, and epoxidized soybean oil are added to a high-speed mixer and mixed for 15 min. Then, the mixed material is added to a twin-screw extruder for melt extrusion to obtain a halogen-free flame-retardant semi-conductive shielding cable compound. The temperature control of the twin-screw extruder is as follows: the feeding zone is 150 °C, the melting zone is 165 °C, the mixing zone is 180 °C, and the die head zone is 175 °C.

[0032] Example 3 A halogen-free flame-retardant semi-conductive shielding cable compound A preparation method of a halogen-free flame-retardant semi-conductive shielding cable compound: Step 1. Preparation of modified mesoporous SiO2 By weight, the raw materials include: 50 parts of tetraethyl orthosilicate (TEOS), 5 parts of γ-aminopropyltriethoxysilane (KH-792), 7 parts of glacial acetic acid, 160 parts of ethanol, 56 parts of deionized water, and 4 parts of alkyl polyglycoside (APG).

[0033] TEOS, ethanol, glacial acetic acid, and deionized water are mixed and stirred to hydrolyze and generate a uniform and transparent SiO2 sol. KH-792 is added to the SiO2 sol, and ultrasonic reaction is carried out at 85 °C and 26 kHz for 3 h. After the ultrasonic reaction, APG is added, and ultrasonic treatment is continued for 1.5 h. The material after ultrasonic treatment is centrifuged to retain the solid phase. The solid phase is calcined at 600 °C for 3 h to obtain modified mesoporous SiO2.

[0034] Step 2. Loading of conductive agent and flame retardant By weight, the raw materials include: 3 parts of single-walled carbon nanotubes (SWCNTs), 3 parts of graphene nanosheets (GNSs), 4 parts of conductive carbon black, 0.02 part of sodium dodecylbenzenesulfonate (SDBS), 60 parts of modified mesoporous SiO2, 11 parts of melamine phosphate (MPP), and 5 parts of zinc borate (ZB).

[0035] SWCNTs, GNSs, conductive carbon black, and SDBS are put into DMF, and ultrasonic treatment is carried out at 32 kHz for 2 h. Then, modified mesoporous SiO2, MPP, and ZB are added and stirred for 30 min to obtain a mixed solution. The mixed solution is ultrasonically dispersed at 32 kHz for 1 h. After the ultrasonic dispersion, the mixed solution is filtered to retain the solid, and the solid is vacuum dried at 80 °C for 8 h to obtain mesoporous SiO2 loaded with conductive agent and flame retardant.

[0036] DMF is used as a solvent and does not participate in the reaction. The dosage is based on the ability to dissolve the solute.

[0037] Step 3. Melting and blending to prepare the cable compound By weight, the raw materials include: 55 parts of low-density polyethylene (LDPE), 75 parts of ethylene-vinyl acetate copolymer (EVA), 78 parts of mesoporous SiO2 loaded with a conductive agent and a flame retardant, 2 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 6 parts of zinc stearate, and 8 parts of epoxidized soybean oil.

[0038] First, add LDPE, EVA, mesoporous SiO2 loaded with a conductive agent and a flame retardant, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], zinc stearate, and epoxidized soybean oil to a high-speed mixer and mix for 15 min. Then, add the mixed material to a twin-screw extruder for melt extrusion to obtain a halogen-free flame-retardant semi-conductive shielding cable material. The temperature control of the twin-screw extruder is as follows: the feeding zone is 150 °C, the melting zone is 165 °C, the mixing zone is 180 °C, and the die head zone is 175 °C.

[0039] Example 4 A halogen-free flame-retardant semi-conductive shielding cable material A preparation method of a halogen-free flame-retardant semi-conductive shielding cable material: Step 1. Prepare modified mesoporous SiO2 By weight, the raw materials include: 48 parts of tetraethyl orthosilicate (TEOS), 4 parts of γ-aminopropyltriethoxysilane (KH-792), 6 parts of glacial acetic acid, 150 parts of ethanol, 50 parts of deionized water, and 3 parts of alkyl polyglycoside (APG).

[0040] Mix and stir TEOS, ethanol, glacial acetic acid, and deionized water to hydrolyze and generate a uniform and transparent SiO2 sol. Add KH-792 to the SiO2 sol and carry out an ultrasonic reaction at 90 °C and 26 kHz for 2 h. After the ultrasonic reaction ends, add APG and continue ultrasonic treatment for 2 h. Centrifuge the ultrasonically treated material and retain the solid phase. The solid phase is calcined at 530 °C for 5 h to obtain modified mesoporous SiO2.

[0041] Step 2. Load a conductive agent and a flame retardant By weight, the raw materials include: 2 parts of single-walled carbon nanotubes (SWCNTs), 2 parts of graphene nanosheets (GNSs), 5 parts of conductive carbon black, 0.03 part of sodium dodecylbenzenesulfonate (SDBS), 65 parts of modified mesoporous SiO2, 10 parts of melamine phosphate (MPP), and 7 parts of zinc borate (ZB).

[0042] SWCNTs, GNSs, conductive carbon black, and SDBS were added to DMF, and ultrasonic treatment was carried out for 3 h under the condition of 32 kHz. Then, modified mesoporous SiO2, MPP, and ZB were added and stirred for 30 min to obtain a mixed solution; the mixed solution was ultrasonically dispersed for 1 h under the condition of 32 kHz; after the ultrasonic dispersion was completed, the mixed solution was filtered, and the solid was retained. The solid was vacuum dried at 80 °C for 6 h to obtain mesoporous SiO2 loaded with a conductive agent and a flame retardant.

[0043] DMF is a solvent and does not participate in the reaction. The dosage is based on the ability to dissolve the solute.

[0044] Step 3. Preparation of cable material by melt blending By weight, the raw materials include: 50 parts of low-density polyethylene (LDPE), 80 parts of ethylene-vinyl acetate copolymer (EVA), 75 parts of mesoporous SiO2 loaded with a conductive agent and a flame retardant, 4 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 5 parts of zinc stearate, and 6 parts of epoxidized soybean oil.

[0045] First, LDPE, EVA, mesoporous SiO2 loaded with a conductive agent and a flame retardant, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], zinc stearate, and epoxidized soybean oil were added to a high-speed mixer and mixed for 15 min. Then, the mixed material was added to a twin-screw extruder for melt extrusion to obtain a halogen-free flame-retardant semi-conductive shielding cable material. The temperature control of the twin-screw extruder: the feeding zone is 150 °C, the melting zone is 165 °C, the mixing zone is 180 °C, and the die head zone is 175 °C.

[0046] Performance testing The cable materials prepared in Examples 1 to 4 were subjected to performance testing. The test items, test standards adopted, and test results are shown in the following table; Table 1 Performance test results of the cable materials prepared in Examples 1 to 4 Test Items Test Standards Example 1 Example 2 Example 3 Example 4 Volume Resistivity (Ω・cm) GB / T31838.2-2019 8.5×10² 7.2×10² 6.8×10² 8.2×10² Interface Protrusion (mm) GB / T18890.1-2015 0.03 0.03 0.03 0.04 Oxygen Index (%) GB / T2406.2-2009 34 35 34 33 Flame Retardancy GB / T18380.33-2022 Grade A Grade A Grade A Grade A Tensile Strength (MPa) GB / T2951.11-2008 15.6 16.2 17.8 17.1 Elongation at Break (%) GB / T2951.11-2008 403 417 420 415 It can be seen from the data in Table 1 that the volume resistivity of the cable materials prepared in Examples 1 to 4 is as low as 6.8×10²~8.5×10² Ω·cm; the interface protrusion ≤0.04 mm, and the surface is smooth, which can effectively avoid electric field distortion and partial discharge; these characteristics indicate that it has better electric field shielding ability. The oxygen index of the cable materials prepared in Examples 1 to 4 > 33%, the tensile strength is above 15 MPa, and the elongation at break > 400%, indicating that it has excellent flame retardant performance and mechanical properties.

[0047] The single-walled carbon nanotubes used in Examples 1-4 of the present invention: diameter 1~2 nm, aspect ratio > 10 4; The graphene nanosheets used: thickness 3 - 5 nm, diameter 5 - 10 μm; the conductive carbon black used: particle size 30 - 40 nm; low density polyethylene (LDPE), density 0.910 - 0.925 g / cm³; ethylene-vinyl acetate copolymer (EVA), density 0.91 - 0.94 g / cm³, vinyl acetate content 30 - 40 wt%.

[0048] Obviously, there are many specific implementation methods that can be varied under the concept of the present invention. Here, it should be stated that any changes made under the inventive concept of the present invention will fall within the protection scope of the present invention.

Claims

1. A halogen-free flame-retardant semiconductive shielding cable compound, characterized in that: By weight, the raw materials include 40-55 parts of low-density polyethylene, 75-92 parts of ethylene-vinyl acetate copolymer, 75-85 parts of mesoporous SiO2 loaded with a conductive agent and a flame retardant, 2-4 parts of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-6 parts of zinc stearate, and 5-8 parts of epoxidized soybean oil; The mesoporous SiO2 loaded with a conductive agent and a flame retardant: is made from the following raw materials: single-walled carbon nanotubes, graphene nanosheets, conductive carbon black, sodium dodecylbenzenesulfonate, melamine phosphate, zinc borate, modified mesoporous SiO2; The modified mesoporous SiO2: uses γ-aminopropyltriethoxysilane and alkyl polyglycoside as modifiers.

2. The halogen-free flame-retardant semiconductive shielding cable compound according to claim 1, wherein: The mesoporous SiO2 loaded with a conductive agent and a flame retardant, by weight, the raw material ratio is: 2-4 parts of single-walled carbon nanotubes, 2-5 parts of graphene nanosheets, 4-6 parts of conductive carbon black, 0.02-0.05 parts of sodium dodecylbenzenesulfonate, 60-70 parts of modified mesoporous SiO2, 10-15 parts of melamine phosphate, and 5-9 parts of zinc borate.

3. The preparation method of a halogen-free flame-retardant semiconductive shielding cable compound according to claim 1, characterized in that: It includes steps of preparing modified mesoporous SiO2, loading a conductive agent and a flame retardant, and melt-blending to prepare cable materials.

4. The preparation method of a halogen-free flame-retardant semi-conductive shielding cable material according to claim 3, wherein: The preparation of the modified mesoporous SiO2: Mix tetraethyl orthosilicate, ethanol, glacial acetic acid, and deionized water and stir to hydrolyze to form a uniform and transparent SiO2 sol; Add γ-aminopropyltriethoxysilane to the SiO2 sol and perform ultrasonic treatment; Then add alkyl polyglycoside, after ultrasonic treatment, centrifuge and retain the solid phase; Calcinate the solid phase to obtain modified mesoporous SiO2.

5. The preparation method of a halogen-free flame-retardant semi-conductive shielding cable compound according to claim 3, characterized in that: The raw materials for the preparation of the modified mesoporous SiO2, by weight, the ratio is 45-50 parts of tetraethyl orthosilicate, 2-5 parts of γ-aminopropyltriethoxysilane, 5-7 parts of glacial acetic acid, 150-160 parts of ethanol, 50-60 parts of deionized water, and 3-5 parts of alkyl polyglycoside.

6. The preparation method of a halogen-free flame-retardant semiconductive shielding cable compound according to claim 4, characterized in that: The calcination: Calcinate at 500-600 °C for 3-6 h.

7. The preparation method of a halogen-free flame-retardant semiconductive shielding cable compound according to claim 3, wherein: The loading of the conductive agent and the flame retardant: Put single-walled carbon nanotubes, graphene nanosheets, conductive carbon black, and sodium dodecylbenzenesulfonate into N,N-dimethylformamide and perform ultrasonic treatment; Then add modified mesoporous SiO2, melamine phosphate, and zinc borate and stir to obtain a mixed solution; Ultrasonically disperse the mixed solution, after the ultrasonic dispersion ends, filter the mixed solution and retain the solid; The solid is vacuum dried to obtain mesoporous SiO2 loaded with a conductive agent and a flame retardant.

8. The preparation method of a halogen-free flame-retardant semiconductive shielding cable material according to claim 3, characterized in that: The melt-blending to prepare cable materials: Mix low-density polyethylene, ethylene-vinyl acetate copolymer, mesoporous SiO2 loaded with a conductive agent and a flame retardant, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], zinc stearate, and epoxidized soybean oil and then add them to a twin-screw extruder for melt extrusion.

9. The preparation method of a halogen-free flame-retardant semi-conductive shielding cable compound according to claim 8, wherein: The low-density polyethylene: has a density of 0.910-0.925 g / cm³.

10. The preparation method of a halogen-free flame-retardant semiconductive shielding cable compound according to claim 8, characterized in that: The ethylene-vinyl acetate copolymer: has a density of 0.91-0.94 g / cm³ and an acetic acid vinyl content of 30-40 wt%.