A kind of fast-crosslinking silane crosslinked inner shielding material and its preparation method and application

Abstract

The present invention relates to a fast-crosslinking silane-crosslinked inner shielding material, which comprises the following raw materials in parts by weight: 10-20 parts of ethylene-vinyl acetate copolymer, 20-55 parts of low-density polyethylene, 10-30 parts of metallocene polyethylene, 0.05-5 parts of polyethylene wax, 26-38 parts of conductive carbon black, 1-4 parts of lubricating auxiliary agent, 0.05-1 part of antioxidant, 0.5-2 parts of silane coupling agent, 0.04-0.15 part of initiator, and 0.03-0.1 part of catalyst. The fast-crosslinking silane-crosslinked inner shielding material of the present invention can improve the production efficiency and service life of the cable without changing the existing processing technology of the silane-crosslinked cable.

Description

Technical Field

[0001] The present invention relates to a fast-crosslinking silane-crosslinked inner shielding material, a preparation method thereof and an application thereof, belonging to the technical field of cable material production. Background Art

[0002] With the improvement of cable industry standards and the increase of voltage grades of silane-crosslinked cables, the temperature resistance requirement of the inner screen of the cable is getting higher and higher. The previously used thermoplastic shielding material can no longer meet the requirements of the cable. At present, more and more 10KV overhead cables use crosslinked inner screens to ensure the safety of the cable. Chinese Patent Application CN107868328A discloses a silane-crosslinked semi-conductive shielding material, a preparation method thereof and an application thereof. The semi-conductive shielding material is prepared by mixing A material and B material with a mass ratio of 2-5:1 and crosslinking in water. By weight, the raw materials of the A material include ethylene-butyl acrylate copolymer, bimodal polyethylene, conductive carbon black, antioxidant, silane, initiator, lubricating auxiliary and dispersant; the raw materials of the B material include bimodal polyethylene and hydrolysis catalyst; the butyl acrylate content in the ethylene-butyl acrylate copolymer is 10-30%, and the melt index of the bimodal polyethylene is 0.1-20 g / 10min. The semi-conductive shielding material prepared by this method has properties such as a relatively high temperature resistance grade, good mechanical strength and low volume resistivity, and has advantages such as mild preparation conditions and fast reaction speed. However, since the insulation thickness of the 10KV overhead line is 3.4mm, and the inner screen is in the inner layer of the insulation and is not easy to contact moisture and heat, the crosslinking is relatively slow.

[0003] At present, the production process of 10KV overhead lines is a 70 single-screw plus 120 single-screw extrusion equipment. Since the inner screen accounts for a small proportion in the cable, the extrusion speed of the shielding material extruder is slow during the extrusion process. On the other hand, since the insulation thickness of the 10KV overhead line is relatively thick, the current ordinary fast-crosslinking silane-crosslinked inner shielding material needs 14 hours in a 90-degree Celsius steam room to be completely crosslinked. It is particularly important to increase the crosslinking speed of the silane-crosslinked shielding material, reduce the steam time, reduce energy consumption and improve production efficiency. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a fast-crosslinking silane-crosslinked inner shielding material to increase the crosslinking speed, reduce the steam time, reduce energy consumption and improve production efficiency.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A fast-crosslinking silane-crosslinked inner shielding material, comprising the following raw materials in parts by weight:

[0007] 10 - 20 parts of ethylene - vinyl acetate copolymer, 20 - 55 parts of low - density polyethylene, 10 - 30 parts of metallocene polyethylene, 0.05 - 5 parts of polyethylene wax, 26 - 38 parts of conductive carbon black, 1 - 4 parts of lubricating aid, 0.05 - 1 part of antioxidant, 0.5 - 2 parts of silane coupling agent, 0.04 - 0.15 part of initiator, 0.03 - 0.1 part of catalyst.

[0008] In the present invention, by using low - density polyethylene as the matrix and adding conductive carbon black, a fast - crosslinking silane - crosslinked inner shielding material for insulation with appropriate conductivity can be obtained; by adding ethylene - vinyl acetate copolymer, the extrusion surface of the material is smooth and flat, and good mechanical properties can be maintained in the case of filling a large amount of conductive carbon black; by adding polyethylene wax (PE wax), the conductive carbon black in the material can be evenly dispersed, preventing agglomeration during the extrusion process; by adding metallocene polyethylene and silane coupling agent, not only the process requirements of cable production are met, but also the crosslinking speed of the product is increased, the steam time is reduced, the energy consumption is lowered, and the production efficiency is improved.

[0009] Preferably, the fast - crosslinking silane - crosslinked inner shielding material comprises the following raw materials in parts by weight:

[0010] 12 - 14 parts of ethylene - vinyl acetate copolymer, 49 - 53 parts of low - density polyethylene, 10 - 30 parts of metallocene polyethylene, 2 - 4 parts of polyethylene wax, 28 - 32 parts of conductive carbon black, 1 - 1.5 parts of lubricating aid, 0.2 - 0.4 part of antioxidant, 1 - 1.5 parts of silane coupling agent, 0.06 - 0.12 part of initiator, 0.04 - 0.08 part of catalyst.

[0011] When the addition amount of the lubricating aid is 1 - 1.5 parts, a good lubricating effect can be achieved and it is not easy to precipitate; when the addition amount of conductive carbon black is 28 - 32 parts, the mechanical properties and conductivity of the product reach a balance; when the addition amount of PE wax is 2 - 4 parts, it is beneficial to the better dispersion of conductive carbon black, beneficial to a smoother and flatter extrusion surface, making the present invention have better conductivity and mechanical properties.

[0012] Furthermore, the mass ratio of the ethylene - vinyl acetate copolymer, low - density copolymer, and metallocene polyethylene is 10:70:15 - 20:50:30, preferably 15:65:20.

[0013] Furthermore, the mass ratio of the silane coupling agent, initiator, and catalyst is 0.7:0.06:0.03 - 2:0.12:0.08.

[0014] In some embodiments of the present invention, the addition amounts of the ethylene-vinyl acetate copolymer are 11 parts, 13 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, etc. by weight; the addition amounts of the low-density polyethylene are 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts; the addition amounts of the metallocene polyethylene are 10 parts, 15 parts, 20 parts, 25 parts, 30 parts; the addition amounts of the polyethylene wax are 1 part, 2 parts, 3 parts, 4 parts, 5 parts; the addition amounts of the conductive carbon black are 26 parts, 27 parts, 28 parts, 29 parts, 31 parts, 32 parts, 33 parts; the addition amounts of the lubricating auxiliary agent are 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts; the addition amounts of the antioxidant are 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.6 parts; the addition amounts of the silane coupling agent are 1.0 part, 1.1 parts, 1.2 parts, 1.4 parts, 1.5 parts; the addition amounts of the initiator are 0.06 part, 0.08 part, 0.1 part, 0.105 part, 0.11 part, 0.12 part; the addition amounts of the catalyst are 0.04 part, 0.05 part, 0.06 part, 0.07 part, 0.08 part.

[0015] Preferably, the fast-crosslinking silane-crosslinked inner shielding material comprises the following raw materials in parts by weight:

[0016] 10 parts of ethylene-vinyl acetate copolymer, 35 parts of low-density polyethylene, 20 parts of metallocene polyethylene, 2 parts of polyethylene wax, 30 parts of conductive carbon black, 1.5 parts of lubricating auxiliary agent, dispersant, 0.45 part of antioxidant, 1 part of silane coupling agent, 0.08 part of initiator, 0.06 part of catalyst.

[0017] In some embodiments of the present invention, when the addition amount of the ethylene-vinyl acetate copolymer is 10 parts, the addition amount of the linear low-density polyethylene is 35 parts, and the addition amount of the metallocene low-density polyethylene is 20 parts, the prepared fast-crosslinking silane-crosslinked inner shielding material has good process performance, mechanical properties and anti-aging properties.

[0018] Furthermore, the antioxidant is at least one of 4,4′-thiobis(6-tert-butyl-m-cresol) and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Preferably, the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0019] Furthermore, the silane coupling agent is used as a crosslinking agent, and the silane coupling agent is at least one of vinyltrimethoxysilane and vinyltris(β-methoxyethoxy)silane.

[0020] Furthermore, the initiator is dicumyl peroxide.

[0021] Further, the catalyst is dibutyltin dilaurate.

[0022] Further, the lubrication aid is zinc stearate.

[0023] Further, the melt index of the ethylene-vinyl acetate copolymer at 190 °C and 2.16 kg is 6-8 g / 10 min, and the VA content is 15-18%.

[0024] Further, the low-density polyethylene is linear low-density polyethylene, preferably an ethylene-octene copolymer with a melt index of 2 g / 10 min at 190 °C and 2.16 kg, which has good mechanical properties and still has good low-temperature impact performance at -50 °C.

[0025] Further, the metallocene polyethylene is preferably a metallocene copolymer with a melt index of 3.5 g / 10 min at 190 °C and 2.16 kg, which has good mechanical properties and still has good low-temperature impact performance at -50 °C.

[0026] Further, the number-average molecular weight of the polyethylene wax is 2000-4000. High-molecular-weight polyethylene wax can not only improve the dispersion of conductive carbon black but also reduce the die lip flow during the extrusion of the product.

[0027] In some embodiments of the present invention, the conductive carbon black is at least one of Yongdong 260 conductive carbon black, YD-250C conductive carbon black, YD-210 conductive carbon black, and Columbia 7090 conductive carbon black.

[0028] A preparation method of the above-mentioned fast-crosslinking silane-crosslinked inner shielding material, which comprises the following steps:

[0029] S1. Add polyethylene wax, lubrication aid, and antioxidant into a high-speed mixer for premixing to obtain a premixed product;

[0030] S2. Put the ethylene-vinyl acetate copolymer, low-density polyethylene, and conductive carbon black together with the premixed product obtained in step S1 into a reciprocating machine through a metering scale and mix them into a mature rubber (i.e., a jelly-like substance);

[0031] S3. Feed the mixed mature rubber into a single-screw extruder for extrusion and strand pelletization. After screening out irregular particles through a vibrating screen, air-dry, cool, and pack the obtained particles to obtain a semi-finished product;

[0032] S4. Premix the silane coupling agent and the initiator through a stirrer to obtain a mixed solution;

[0033] S5. Meter the semi-finished product obtained in step S3 and the mixed liquid obtained in step S4, add them to a twin-screw for grafting, then extrude and pelletize through a single-screw, and vacuum package the obtained particles with an aluminum-plastic bag after drying through a dehydrator and a fluidized bed, as component A;

[0034] S6. Stir the semi-finished product obtained in step S3 with an antioxidant and a catalyst through a high-speed mixer, then add them to a twin-screw for extrusion and strand pelletization, and package with an aluminum-plastic bag after drying, as component B;

[0035] S7. Mix component A and component B to obtain a fast-crosslinking silane-crosslinked inner shielding material.

[0036] Further, the mass ratio of the antioxidant in steps S1 and S6 is 1∶1 - 1.5∶1.

[0037] Further, in step S7, the mass ratio of component A to component B is 90∶10 - 97∶3.

[0038] An application of a fast-crosslinking silane-crosslinked inner shielding material in a 10KV overhead cable.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) For the fast-crosslinking silane-crosslinked inner shielding material of the present invention, without changing the existing processing technology of silane-crosslinked cables, it can improve the crosslinking speed, reduce the steam time, lower the energy consumption, and improve the production efficiency and service life of the cables, etc.

[0041] (2) The raw materials of the preparation method of the fast-crosslinking silane-crosslinked inner shielding material of the present invention are easy to obtain, the preparation steps are simple and feasible, and it is suitable for mass production. Specific Embodiments

[0042] The following will describe the present invention in detail with reference to embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through the market, and the content of each component is in parts by weight.

[0043] Example 1

[0044] The present invention provides a fast-crosslinking silane-crosslinked inner shielding material, which comprises raw materials with the following weight components: 10 parts of ethylene-vinyl acetate copolymer, 40 parts of linear low-density polyethylene, 20 parts of metallocene polyethylene, 30 parts of conductive carbon black, 2 parts of PE wax, 1.5 parts of zinc stearate, 0.45 part of 4,4′-thiobis(6-tert-butyl-m-cresol), 0.05 part of dicumyl peroxide, 1 part of vinyltris(β-methoxyethoxy)silane, and 0.06 part of dibutyltin dilaurate. The main reagents and manufacturers are shown in Table 1.

[0045] Table 1 Main Reagents and Manufacturers

[0046] Reagent Name Manufacturer Model Ethylene-vinyl acetate copolymer Yangzi Petrochemical-BASF Co., Ltd. 5110J Linear low density polyethylene Chuanhua Group Co., Ltd. 7042N Metallocene polyethylene ExxonMobil Corporation 3518 PE wax China Petrochemical Corporation Yanshan Petrochemical Company / Vinyltri(b-methoxyethoxy)silane Shandong Silicate New Materials Co., Ltd. / Dicumyl peroxide Jiangsu Daoming Chemical Co., Ltd. / Carbon black / VXC200

[0047] The preparation method of the fast-crosslinking silane-crosslinked inner shielding material is as follows:

[0048] S1. Take 2 parts of PE wax with a number-average molecular weight of 2000 - 4000, 0.25 part of 4,4′-thiobis(6-tert-butyl-m-cresol), and 1.5 parts of zinc stearate, add them to a blender for premixing to obtain a premixed product;

[0049] S2. Weigh 40 parts of linear low-density polyethylene, 10 parts of ethylene-vinyl acetate copolymer, 20 parts of metallocene polyethylene, and 30 parts of carbon black, and put them together with the premixed product obtained in step S1 into a reciprocating machine through a metering scale for mixing and kneading to form a mature rubber (i.e., a jelly-like substance);

[0050] S3. Feed the mature rubber into a single-screw extruder for extrusion and pelletizing. After the obtained pellets are screened through a vibrating screen to remove irregular particles, they are air-dried and cooled to obtain semi-finished products;

[0051] S4. Take 1 part of vinyltris(β-methoxyethoxy)silane and 0.05 part of dicumyl peroxide, and premix them in proportion through a blender to obtain a mixed liquid;

[0052] S5. Weigh 100 parts of the semi-finished product obtained in step S3 and the mixed liquid obtained in step S4 through a metering scale, add them to a twin-screw extruder for grafting, and then perform single-screw extrusion pelletizing. The obtained pellets are dried through a dehydrator and a fluidized bed, and then vacuum-packed in an aluminum-plastic bag to obtain Component A;

[0053] S6. Weigh 100 parts of the semi-finished product obtained in step S3, 0.2 part of 4,4′-thiobis(6-tert-butyl-m-cresol), and 0.06 part of dibutyltin dilaurate, stir them through a high-speed mixer, then add them to a twin-screw extruder for extrusion and pelletizing, and after drying, pack them in an aluminum-plastic bag to obtain Component B;

[0054] S7. Mix Component A and Component B in a mass ratio of 95:5 to obtain the fast-crosslinking silane-crosslinked inner shielding material.

[0055] Among them, the vacuum-packed weight of component A is 23.75 KG, and the vacuum-packed weight of component A is 1.25 KG.

[0056] Example 2

[0057] The difference between this example and Example 1 is that 1.2 parts of vinyltris(β-methoxyethoxy)silane and 0.06 part of dicumyl peroxide are added in step S4, and the remaining components are the same as those in Example 1. And the preparation process of Example 2 is the same as that of Example 1, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0058] Example 3

[0059] The difference between this example and Example 1 is that 1.2 parts of vinyltris(β-methoxyethoxy)silane and 0.07 part of dicumyl peroxide are added in step S4, and the remaining components are the same as those in Example 1. And the preparation process of Example 3 is the same as that of Example 1, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0060] Example 4

[0061] The difference between this example and Example 1 is that 1.2 parts of vinyltris(β-methoxyethoxy)silane and 0.08 part of dicumyl peroxide are added in step S4, and the remaining components are the same as those in Example 1. And the preparation process of Example 4 is the same as that of Example 1, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0062] Example 5

[0063] The difference between this example and Example 1 is that 1.2 parts of vinyltris(β-methoxyethoxy)silane, 0.08 part of dicumyl peroxide, and 0.08 part of dibutyltin dilaurate are added in step S4, and the remaining components are the same as those in Example 1. And the preparation process of Example 5 is the same as that of Example 1, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0064] Example 6

[0065] The difference between this example and Example 1 is that 1.2 parts of vinyltris(β-methoxyethoxy)silane, 0.08 part of dicumyl peroxide, and 0.1 part of dibutyltin dilaurate are added in step S4, and the remaining components are the same as those in Example 1. And the preparation process of Example 6 is the same as that of Example 1, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0066] Example 7

[0067] The difference between this embodiment and Embodiment 1 is that 1.2 parts of vinyltris(β-methoxyethoxy)silane, 0.08 part of dicumyl peroxide, and 0.12 part of dibutyltin dilaurate are added in step S4, and the remaining components are the same as those in Embodiment 1. Moreover, the preparation process of Embodiment 7 is the same as that of Embodiment 1, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0068] Comparative Example 1

[0069] Replace the metallocene polyethylene in Example 6 with linear low-density polyethylene, that is, the metallocene polyethylene is 0 part, that is, the linear low-density polyethylene is 60 parts, and the rest are the same as those in Example 6. Moreover, the preparation process of Comparative Example 1 is the same as that of Example 6, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0070] Comparative Example 2

[0071] Replace the linear low-density polyethylene in Example 6 with metallocene polyethylene, that is, the linear polyethylene is 0 part, and the metallocene polyethylene is 60 parts, and the rest are the same as those in Example 6. Moreover, the preparation process of Comparative Example 1 is the same as that of Example 6, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0072] Comparative Example 3

[0073] Replace the ethylene-vinyl acetate in Example 7 with linear low-density polyethylene, that is, the ethylene-vinyl acetate is 0 part, that is, the linear low-density polyethylene is 50 parts, and the rest are the same as those in Example 7. Moreover, the preparation process of Comparative Example 1 is the same as that of Example 7, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0074] Comparative Example 4

[0075] Replace 1.2 parts of vinyltris(β-methoxyethoxy)silane in Example 7 with 1.2 parts of vinyltrimethoxysilane, and the rest are the same as those in Example 7. Moreover, the preparation process of Comparative Example 3 is the same as that of Example 7, and a fast-crosslinking silane-crosslinked inner shielding material is prepared.

[0076] Example 8 Performance Test of the Invention

[0077] Carry out relevant performance tests on the fast-crosslinking silane-crosslinked inner shielding materials prepared in Examples 1-7 and Comparative Examples 1-4 according to the test standards and requirements in Table 2 below, and the results are shown in Tables 3 and 4. Among them, the crosslinking speed of the product is tested at 50°C in a water bath and in a natural state, and the crosslinking speed of the product is judged by the heat elongation at different times, as shown in Table 5 specifically.

[0078] Results and Analysis:

[0079] For the fast-crosslinking silane-crosslinked inner shielding materials of Examples 1-7 of the present invention, their performances meet the requirements of 10738-2014.

[0080] As can be seen from Table 3-5, in Examples 1-4, with the increase in the addition amount of dicumyl peroxide, the final heat elongation of the fast-crosslinking silane-crosslinked inner shielding material decreased. Considering the process performance, 0.08 was selected as appropriate.

[0081] In Examples 5-7, with the increase in the addition amount of dibutyltin dilaurate, the crosslinking speed of the fast-crosslinking silane-crosslinked inner shielding material first increased, and when the addition amount exceeded a certain amount, the crosslinking speed tended to level off.

[0082] In Comparative Example 1, when metallocene polyethylene was not used, the tensile strength and elongation at break of the obtained product after aging both decreased significantly, far lower than those in Example 6.

[0083] From the performance test results of the products obtained in Example 6 and Comparative Example 2, it can be seen that when the amount of metallocene increased, the performance of the material was not affected, but the metallocene would cause an increase in the screw torque, reducing the production capacity and increasing the energy consumption.

[0084] From the performance test results of the products obtained in Example 6 and Comparative Example 3, it can be seen that when ethylene-vinyl acetate was not used, the performance of the material was not affected, but the crosslinking speed of the material decreased, and ethylene-vinyl acetate could improve the extrusion surface of the material and reduce the screw torque.

[0085] From the performance test results of the products obtained in Example 6 and Comparative Example 4, it can be seen that when vinyltri(β-methoxyethoxy)silane was used, due to the faster condensation reaction of vinyltri(β-methoxyethoxy)silane, the crosslinking speed of the silane-crosslinked inner shielding material was increased.

[0086] Table 2 Performance Test Standards and Requirements of the Present Invention

[0087]

[0088] Table 3 Performance Test Results of the Fast-Crosslinking Silane-Crosslinked Inner Shielding Material Obtained in Examples 1-7

[0089]

[0090] Table 4 Performance Test Results of the Fast-Crosslinking Silane-Crosslinked Inner Shielding Material Obtained in Comparative Examples 1-4

[0091]

[0092] Table 5 Heat Elongation at 50°C in a Water Bath and in the Natural State

[0093]

[0094] The content illustrated in the above embodiments should be understood that these embodiments are only used to illustrate the present invention more clearly, rather than to limit the scope of the present invention. After reading the present invention, various equivalent forms of modification made by those skilled in the art to the present invention all fall within the scope defined by the appended claims of this application.

Claims

1. A fast-crosslinking silane-crosslinked inner shielding material, characterized in that, It comprises the following raw materials in parts by weight: 10 - 20 parts of ethylene - vinyl acetate copolymer, 20 - 55 parts of low - density polyethylene, 10 - 30 parts of metallocene polyethylene, 0.05 - 5 parts of polyethylene wax, 26 - 38 parts of conductive carbon black, 1 - 4 parts of lubricating auxiliary agent, 0.05 - 1 part of antioxidant, 0.5 - 2 parts of silane coupling agent, 0.04 - 0.15 part of initiator, and 0.03 - 0.1 part of catalyst; the silane coupling agent is at least one of vinyltrimethoxysilane and vinyltri(β - methoxyethoxy)silane; the initiator is dicumyl peroxide; the catalyst is dibutyltin dilaurate.

2. The fast-crosslinking silane-crosslinked inner shielding material according to claim 1, wherein The mass ratio of the ethylene - vinyl acetate copolymer, low - density polyethylene, and metallocene polyethylene is 10:70:15 - 20:50:

30.

3. The fast-crosslinking silane crosslinked inner shielding material according to claim 1, characterized in that, The mass ratio of the silane coupling agent, initiator, and catalyst is 0.7:0.06:0.03 - 2:0.12:0.

08.

4. The fast-crosslinking silane-crosslinked inner shielding compound according to claim 1, wherein It comprises the following raw materials in parts by weight: 10 parts of ethylene - vinyl acetate copolymer, 35 parts of low - density polyethylene, 20 parts of metallocene polyethylene, 2 parts of polyethylene wax, 30 parts of conductive carbon black, 1.5 parts of lubricating auxiliary agent, 0.45 part of antioxidant, 1 part of silane coupling agent, 0.08 part of initiator, and 0.06 part of catalyst.

5. The fast-crosslinking silane-crosslinked inner shielding compound according to claim 1, characterized in that, The antioxidant is at least one of 4,4'-thiobis(6 - tert - butyl - m - cresol) and pentaerythritol tetra[β - (3,5 - di - tert - butyl - 4 - hydroxyphenyl)propionate]; the lubricating auxiliary agent is zinc stearate.

6. The fast-crosslinking silane crosslinked inner shielding material according to claim 1, wherein The number - average molecular weight of the polyethylene wax is 2000 - 4000.

7. The preparation method of the fast-crosslinking silane crosslinked inner shielding material according to any one of claims 1-6, characterized in that, It comprises the following steps: S1. Add the polyethylene wax, lubricating auxiliary agent, and antioxidant into a high - speed mixer for premixing to obtain a premixed product. S2. Weigh the ethylene - vinyl acetate copolymer, low - density polyethylene, and conductive carbon black and put them together with the premixed product obtained in step S1 into a reciprocating machine for mixing and kneading to form a mature rubber. S3. Feed the kneaded mature rubber into a single - screw extruder for extrusion and strand pelletization. After screening out irregular particles through a vibrating screen, air - dry and cool the obtained particles and then pack them to obtain semi - finished products. S4. Premix the silane coupling agent and initiator through a stirrer to obtain a mixed solution. S5. Weigh the semi - finished products obtained in step S3 and the mixed solution obtained in step S4 and add them into a twin - screw extruder for grafting, then extrude and pelletize through a single - screw extruder. The obtained particles are dried through a dehydrator and a fluidized bed and then vacuum - packed with an aluminum - plastic bag to obtain component A. S6. Stir the semi - finished products obtained in step S3 with the antioxidant and catalyst through a high - speed mixer, then add them into a twin - screw extruder for extrusion and strand pelletization, and pack them with an aluminum - plastic bag after drying to obtain component B. S7. Mix component A and component B to obtain a fast - crosslinking silane - crosslinked inner shielding material. The mass ratio of component A to component B is 90:10 - 97:

3.

8. The preparation method of the fast-crosslinking silane-crosslinked inner shielding material according to claim 7, characterized in that, The mass ratio of the antioxidant in step S1 to that in step S6 is 1:1 - 1.5:

1.

9. The application of the fast - crosslinking silane - crosslinked inner shielding material according to any one of claims 1 - 6 in a 10KV overhead cable.

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