Crosslinked polyethylene insulating material raw material composition, insulating material and preparation method thereof

Abstract

The invention relates to a cross-linked polyethylene insulating material raw material composition, an insulating material and a preparation method thereof. The cross-linked polyethylene insulating material raw material composition is prepared from the following components in parts by weight: 97 to 99 parts of polyethylene, 0.9 to 1.7 parts of a cross-linking agent, 0.2 to 0.5 part of a cross-linking auxiliary agent and 0.1 to 0.3 part of an antioxidant, wherein the molecular weight distribution of the polyethylene ranges from 4.0 PDI to 6.0 PDI. The low-molecular-weight polyethylene resin is adopted as a matrix, a molecular chain segment with a uniform long chain and regular crystallization can be constructed, grains are effectively refined, the crystallinity is improved, and therefore the breakdown field strength and the volume resistivity of the base material are greatly improved. According to the preparation method of the crosslinked polyethylene insulating material, starting from optimization of a crosslinking formula of a compound system, a preparation strategy of insulating low-pressure fluctuation stable extrusion is realized, an insulating extrusion process is effectively optimized, generation of by-products is reduced, and the comprehensive performance of the insulating material is systematically improved.

Description

Technical Field

[0001] This invention belongs to the field of polyethylene insulation materials, specifically relating to a cross-linked polyethylene insulation material raw material composition, insulation material, and preparation method thereof. Background Technology

[0002] High-voltage cross-linked polyethylene (XLPE) cables, thanks to their post-absorption cross-linking process, can construct a stable three-dimensional molecular structure, possessing excellent thermal stability and electrical strength, and are gradually becoming key equipment for urban power grids in modern energy systems. However, most cable-grade polyethylene base materials have relatively high weight-average molecular weights and wide molecular weight distributions. This multi-chain structure makes it difficult for the material to form a regular and uniform crystal structure during crystallization, resulting in poor crystallization behavior, increased probability of internal electric field distortion, and increased phonon propagation path scattering, leading to poor electrical, mechanical, and thermal properties of the composite material. Secondly, the peroxide cross-linking agent is often of a single type and has an excessively high content (DCP ≥ 1.7%), generating multiple byproducts, making degassing difficult, and resulting in insufficient material purity.

[0003] Therefore, there is an urgent need to study new-generation formulations of insulating materials to improve the comprehensive electrical, mechanical, and thermal properties of insulating materials and to achieve stable extrusion of low-crosslinked systems of insulating materials. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of poor electrical, mechanical and thermal properties of existing polyethylene insulation materials.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A cross-linked polyethylene insulation material raw material composition, wherein the raw material comprises the following components by weight: 97-99 parts polyethylene, 0.9-1.7 parts cross-linking agent, 0.2-0.5 parts cross-linking aid, and 0.1-0.3 parts antioxidant;

[0007] The polyethylene has a molecular weight distribution of 4.0 to 6.0 PDI.

[0008] Preferably, the polyethylene has a molecular weight distribution of 4.5 to 5.5 PDI.

[0009] Preferably, the specific heat capacity of the polyethylene is 2.0 to 2.5 J / (g·℃).

[0010] Preferably, the specific heat capacity of the polyethylene is 2.44 to 2.46 J / (g·℃).

[0011] High specific heat capacity polyethylene can improve the temperature resistance and heat dissipation performance of insulation materials, enhance the stability of long-term extrusion processes, and ensure lower extrusion torque and pressure.

[0012] Preferably, the crosslinking agent is one or more of dicumyl peroxide and bis-tert-butyl peroxide.

[0013] Preferably, the crosslinking agent is obtained by mixing dicumyl peroxide and bis-tert-butyl peroxide in a ratio of 4:1.

[0014] By adjusting the ratio of the first type of crosslinking agent, dicumyl peroxide (DCP), to the second type of crosslinking agent, bis(tert-butyl peroxide) (BIPB) (4:1), the crosslinking initiation synergistic effect in the multi-stage insulation extrusion plasticizing process can be achieved, thereby reducing the amount of crosslinking agent used, reducing scorching and by-product generation, reducing product defects, and improving production efficiency and sample quality.

[0015] Preferably, the crosslinking aid is one or more of triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, and polytrilyl isocyanurate.

[0016] Preferably, the antioxidant is one or more of antioxidant 300, antioxidant 1010, antioxidant 168, antioxidant 1035 and antioxidant DLTP.

[0017] Preferably, the antioxidant is obtained by mixing antioxidant 300, antioxidant 1010 and antioxidant 168 in a ratio of 1:1:1.

[0018] Preferably, the product comprises the following components in parts by weight:

[0019] 98 parts polyethylene,

[0020] 0.96 parts of dicumyl peroxide

[0021] 0.24 parts of di-tert-butylperoxide diisopropylbenzene,

[0022] 0.3 parts crosslinking aid,

[0023] 0.5 parts antioxidant.

[0024] This invention also provides a method for preparing cross-linked polyethylene insulation material, comprising the following steps:

[0025] According to the proportion of the cross-linked polyethylene insulation material raw material composition, polyethylene and antioxidant are weighed and blended at high speed to obtain the compound base material;

[0026] The compound base material is mixed and extruded in a flexible mixer, then granulated underwater and dehydrated to obtain insulating granules.

[0027] The insulating granules are heated and dried, and then a uniformly blended crosslinking agent and crosslinking aid are added. After mixing and drying, the mixture is kept warm and absorbed to obtain the crosslinked polyethylene insulating material.

[0028] Preferably, the extrusion temperature is 120℃~180℃.

[0029] Preferably, the outlet pressure during extrusion is ≤0.4MPa and the torque fluctuation is ≤0.7N·m.

[0030] Preferably, the insulating material particles are heated and dried, and then sprayed with a crosslinking agent and crosslinking aid that are uniformly mixed at 55-65°C. The mixing system rotates at 2-8 rpm, and after mixing and drying, the mixture is kept warm and absorbed.

[0031] Preferably, the heat preservation and absorption time is 6 to 10 hours, and the temperature is 50°C to 70°C.

[0032] The present invention also provides a cross-linked polyethylene insulation material, which is prepared using the preparation method of the cross-linked polyethylene insulation material provided by the present invention.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The cross-linked polyethylene insulation material raw material composition proposed in this invention comprises the following components by weight: 97-99 parts polyethylene, 0.9-1.7 parts cross-linking agent, 0.2-0.5 parts cross-linking aid, and 0.1-0.3 parts antioxidant; wherein the molecular weight distribution of the polyethylene is 4.0-6.0 PDI. This invention uses low molecular weight polyethylene resin as the matrix, which can construct long-chain, uniform, and regularly crystalline molecular chain segments, effectively refining the grains and improving crystallinity, thereby significantly improving the breakdown field strength and volume resistivity of the base material. By controlling the amount of cross-linking agent and cross-linking aid, a synergistic effect of cross-linking initiation is achieved in the multi-stage insulation extrusion plasticizing process, thereby reducing the amount of cross-linking agent, reducing scorching and by-product generation, reducing product defects, and improving production efficiency and sample quality, comprehensively improving electrical, mechanical, and thermal properties.

[0035] The method for preparing cross-linked polyethylene insulation material proposed in this invention starts from optimizing the cross-linking formulation of the compound system, and realizes a preparation strategy of stable extrusion with low pressure fluctuations. It effectively optimizes the insulation extrusion process, effectively improves its intrinsic heat dissipation and processing creep resistance, realizes stable extrusion with low pressure fluctuations during pilot extrusion, reduces the generation of by-products, and systematically improves the comprehensive performance of the insulation material. This creates favorable conditions for the preparation of long-length cables and has broad application prospects in the field of cable technology.

[0036] The cross-linked polyethylene insulation material proposed in this invention uses polyethylene base material with ultra-low molecular weight distribution and high specific heat capacity, which can significantly improve the crystallinity and crystallinity of the material, reduce internal electric field distortion, enhance phonon transport free path, and improve the overall electrical, mechanical and thermal properties of the material. Attached Figure Description

[0037] Figure 1 The curves showing the changes in the electromechanical properties and molecular weight distribution of the cross-linked polyethylene insulating materials in Examples 1-3 of the present invention are shown.

[0038] Figure 2 This is a comparison chart of the thermal conductivity of cross-linked polyethylene insulation materials according to embodiments of the present invention. Detailed Implementation

[0039] 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 instances that are improved or modified by those skilled in the art are within the scope of protection of the present invention. It should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the methods used in the embodiments are conventional methods.

[0040] The present invention provides a cross-linked polyethylene insulation material raw material composition, comprising the following components by weight: 97-99 parts polyethylene, 0.9-1.7 parts cross-linking agent, 0.2-0.5 parts cross-linking aid, and 0.1-0.3 parts antioxidant.

[0041] In one embodiment of the present invention, the following components are included by weight: 97-99 parts polyethylene, 1.2 parts crosslinking agent, 0.3 parts crosslinking aid, and 0.3 parts antioxidant.

[0042] The polyethylene is a low molecular weight polyethylene with a high specific heat capacity. The molecular weight distribution of the polyethylene is 4.0–6.0 PDI; the specific heat capacity is 2.0–2.5 J / (g·℃).

[0043] In a preferred embodiment of the present invention, the basic parameters of the polyethylene are: density 0.916 ± 0.001 g / cm³. 3 The molecular weight distribution is 5.0±0.5PDI, the specific heat capacity is 2.45±0.1J / (g·℃), and the melting temperature is 109±0.1℃.

[0044] This invention preferably uses polyethylene base material with ultra-low molecular weight distribution and high specific heat capacity, which can significantly improve the crystallinity regularity and crystallinity of the material, reduce internal electric field distortion, enhance phonon transport free path, and improve the overall electrical, mechanical and thermal properties of the material, thereby effectively improving its intrinsic heat dissipation and processing creep resistance, and achieving stable extrusion with low pressure fluctuations during pilot extrusion.

[0045] Low molecular weight polyethylene (LMWPE) has a molecular weight distribution of 5.0 ± 0.5 PDI. When the weight-average molecular weight is within this range, the molecular chain segments are short and uniform. During crystallization, the grains can be arranged more densely and orderly, forming a more complete crystalline structure. The electric field distribution inside the material is more uniform, reducing the phenomenon of local electric field concentration, thereby improving the electrical properties of the material. When the molecular weight distribution is below this range, the grains are too small, and the entanglement force between molecular chain segments is reduced, which will significantly reduce the flexibility of the base material. When the molecular weight distribution is above this range, the content of long molecular chains increases, making it more difficult for the molecular chains to arrange themselves in a regular manner during crystallization, slowing down the crystallization rate, and potentially reducing the degree of crystallinity. The increase in amorphous regions will significantly reduce the material's breakdown performance, hardness, and rigidity.

[0046] The specific heat capacity of low molecular weight polyethylene is 2.45 ± 0.1 J / (g·℃). When the thermodynamic behavior of the base material is within this range, the overall crystallinity of the base material is high, the molecular chains are arranged in an orderly manner, and the internal defects are significantly reduced. Under the same temperature fluctuation, more heat needs to be absorbed or released, which helps to optimize the high-temperature creep resistance of the base material, optimize the process stability of the material melting and cooling crystallization process, and achieve a stable pilot-scale foundation. When the specific heat capacity is lower than this range, the heat absorption and release capacity of the base material decreases, the overall heat dissipation capacity is insufficient, the interfacial defects increase, the molecular chain interface scattering is severe, and the temperature resistance and stability of the material decrease. Currently, no polyethylene base material with a higher specific heat capacity under this low molecular weight distribution has been found.

[0047] The crosslinking agent includes a first type of crosslinking agent and a second type of crosslinking agent. The first type of crosslinking agent is selected from dicumyl peroxide (DCP) and the second type of crosslinking agent is selected from bis-tert-butyl peroxide (BIPB).

[0048] In a preferred embodiment of the present invention, the total mass fraction of the first type of crosslinking agent DCP and the second type of crosslinking agent BIPB is 1.2 parts. When the optimized ratio is 4:1, the higher proportion of DCP leads to a rapid initiation of the initial crosslinking reaction, resulting in a quickly formed crosslinked structure. As the temperature increases, BIPB gradually decomposes, continuously promoting the crosslinking reaction and perfecting the crosslinking network in subsequent stages, thus improving overall crosslinking efficiency, shortening the processing cycle, and optimizing the overall material performance. When the DCP content is lower than this ratio, it is not conducive to the initial crosslinking and molding of polyethylene, resulting in a slow crosslinking reaction and an uneven crosslinking network. When the DCP content is higher than this ratio, the BIPB content is too low, which is not conducive to improving the high-temperature crosslinking stability of the material and also leads to a decrease in the uniformity of the crosslinking network.

[0049] The crosslinking aid is selected from one or more of triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, and polytrilyl isocyanurate.

[0050] The antioxidant is one or more of antioxidant 300, antioxidant 1010, antioxidant 168, antioxidant 1035, and antioxidant DLTP. In a preferred embodiment of the present invention, the antioxidant is a mixture of thiobisphenol antioxidant 300, hindered phenolic antioxidant 1010, and phosphite antioxidant 168 in a ratio of 1:1:1, which can effectively capture free radicals over a wider temperature range, thereby exhibiting excellent antioxidant performance.

[0051] The present invention also provides a method for preparing the cross-linked polyethylene insulating material, comprising the following steps:

[0052] Weigh out polyethylene and antioxidant in proportion, and blend them at high speed to obtain the compound base material;

[0053] The compound base material is mixed and extruded in a flexible mixer, then granulated underwater and dehydrated to obtain insulating granules.

[0054] The insulating granules are heated and dried, and then a uniformly blended crosslinking agent and crosslinking aid are added. After mixing and drying, the mixture is subjected to absorption treatment to obtain the crosslinked polyethylene insulating material.

[0055] In one embodiment of the present invention, the compound base material is extruded in a single-screw reciprocating compounding extruder, and the heating zone temperature is set as follows: feed inlet: 120℃, 130℃, 140℃; melting section: 150℃, 160℃, 170℃; extrusion section: 170℃ and 180℃; rotation speed is 60 rpm / min; feed rate is 29 rpm / min; and the outlet pressure has a stable extrusion fluctuation range of ≤0.6 MPa.

[0056] In one embodiment of the present invention, a customized 5-layer filter screen is installed during the extrusion process, with a combination of 40 / 80 / 300 to 400 / 100 / 40 mesh, corresponding to a filter screen pore size of approximately 450 / 220 / 60 to 45 / 175 / 450 μm. This filter screen combination can effectively reduce the production of impurity particles, and no insulating particles ≥25 μm are generated after impurity defect detection.

[0057] In one embodiment of the present invention, the pressure fluctuation range of the insulating granules during long-term extrusion of 15 hours is ≤0.4MPa and the torque fluctuation is ≤0.7N·m.

[0058] In one embodiment of the present invention, the absorption process is carried out in a shaking tank at a rotation speed of 5-7 rpm, an absorption time of 6-10 hours, and a temperature of 60-70°C. This process ensures that the high-temperature crosslinking degree of the insulating granules remains above 88%.

[0059] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0060] Example 1

[0061] This embodiment provides a cross-linked polyethylene insulation material raw material composition, which includes the following components by weight: 98 parts polyethylene, 1.2 parts cross-linking agent, 0.3 parts cross-linking aid, and 0.5 parts antioxidant.

[0062] The polyethylene has a molecular weight distribution of 4.0 PDI and a specific heat capacity of 2.3 J / (g·℃).

[0063] The crosslinking agent is DCP;

[0064] The crosslinking aid is triallyl cyanurate;

[0065] The antioxidant is obtained by mixing antioxidant 300, antioxidant 1010 and antioxidant 168 in a ratio of 1:1:1.

[0066] This embodiment also provides a method for preparing cross-linked polyethylene insulation material, including the following steps:

[0067] Weigh out polyethylene and antioxidant in proportion, and pre-mix them evenly in a high-speed mixer to obtain the compound base material;

[0068] The compound base material was extruded and drawn into long strips in a flexible mixer. The heating zone temperatures were set as follows: feed inlet: 120℃, 130℃, 140℃; melting section: 150℃, 160℃, 170℃; extrusion section: 170℃ and 180℃. The rotation speed was 60 rpm / min, the feeding rate was 29 rpm / min, and the outlet pressure was kept within a stable extrusion fluctuation range of ≤0.6 MPa. During the extrusion process, a custom-made 5-layer filter screen was installed, with a combination of 40 / 80 / 300~400 / 100 / 40 mesh, corresponding to a filter screen pore size of approximately 450 / 220 / 60~45 / 175 / 450 μm. After underwater pelletizing, the material was dehydrated and dried to obtain insulating granules.

[0069] The insulating granules were heated and dried, and a compound crosslinking agent and crosslinking aid at 60°C were sprayed in. The mixing system was rotated at 6 rpm. After mixing and drying, the mixture was absorbed at a constant temperature of 60°C in a shaking tank for 8 hours. The shaking speed of the shaking tank was 6 rpm, and crosslinked polyethylene insulating material was obtained.

[0070] Example 2

[0071] The difference from Example 1 is that the polyethylene has a molecular weight distribution of 5.0 PDI and a specific heat capacity of 2.3 J / (g·℃).

[0072] Example 3

[0073] The difference from Example 1 is that the polyethylene has a molecular weight distribution of 6.0 PDI and a specific heat capacity of 2.3 J / (g·℃).

[0074] Example 4

[0075] The difference from Example 1 is that the polyethylene has a molecular weight distribution of 5.0 PDI and a specific heat capacity of 2.45 J / (g·℃).

[0076] Example 5

[0077] The difference from Example 1 is that the polyethylene has a molecular weight distribution of 5.0 PDI and a specific heat capacity of 2.2 J / (g·℃).

[0078] Example 6

[0079] The difference from Example 4 is that the crosslinking agent includes 0.96 parts DCP and 0.24 parts BIPB.

[0080] Example 7

[0081] The difference from Example 1 is that the crosslinking agent includes 0.72 parts DCP and 0.48 parts BIPB.

[0082] Example 8

[0083] The difference from Example 1 is that the crosslinking agent includes 0.48 parts DCP and 0.72 parts BIPB.

[0084] Example 9

[0085] The difference from Example 1 is that the crosslinking agent includes 0.24 parts DCP and 0.96 parts BIPB.

[0086] Test case

[0087] The breakdown field strength of the sample was tested in an insulating oil environment at room temperature using a spherical electrode breakdown system. The specific heat capacity of the material was calculated using differential scanning calorimetry, and the thermal diffusivity of the material was calculated using laser thermal conductivity. The formula for calculating the thermal conductivity of the material is k = ρ × α × C, where ρ is the material density, α is the thermal diffusivity of the material, and C is the specific heat capacity of the material. The results are shown in Table 1.

[0088] Table 1 Test Results

[0089]

[0090] A comparison of Examples 1-3 shows that as the molecular weight distribution increases from 4PDI to 6PDI, the overall thermal, mechanical, and electrical properties of the insulating material first increase and then decrease, with an optimal distribution of 5PDI. At this point, the material's overall performance reaches its optimal value: effective thermal conductivity 0.375 W / (m·K), breakdown field strength reaches a maximum of 375 kV / mm, tensile strength 16.8 MPa, and elongation at break 563%. Figure 1As shown, the curves of the change in electrical and mechanical properties and molecular weight distribution of the cross-linked polyethylene insulating materials in Examples 1 to 3 are shown. The results show that when the weight-average molecular weight distribution is 5PDI, the molecular chain segments are short and uniform. During the crystallization process, the grains can be arranged more densely and orderly to form a more perfect crystal structure. The electric field distribution inside the material is more uniform, reducing the phenomenon of local electric field concentration, thereby improving the electrical, mechanical and thermal properties of the material.

[0091] A comparison of Examples 2 and 4-5 reveals that by selecting a high specific heat capacity base material, the material needs to absorb or release more heat under the same temperature fluctuations. This helps optimize the high-temperature creep resistance of the base material, improves the process stability of the material's melting and cooling crystallization processes, and achieves stable pilot-scale extrusion with pressure fluctuations reduced to ≤1.1 MPa. When the specific heat capacity is below this range, the base material's heat absorption and release capacity decreases, overall heat dissipation capacity is insufficient, interfacial defects increase, molecular chain interfacial scattering is severe, the material's temperature resistance and stability decrease, and the extrusion pressure significantly increases to ≤2.3 MPa.

[0092] Comparing Examples 2 with Examples 6-9, it was found that optimizing the ratio of the two materials to 4:1 further improved the overall material performance, resulting in an effective thermal conductivity of 0.392 W / (m·K), a maximum breakdown field strength of 388 kV / mm, a tensile strength of 18.8 MPa, an elongation at break of 577%, and a relatively low pressure fluctuation of ≤1.1 MPa. This is because a higher proportion of DCP facilitates the rapid initiation of the early cross-linking reaction in the insulating material, allowing the system to quickly form a certain cross-linked structure. As the temperature rises subsequently, BIPB gradually decomposes, and the continued advancement of the cross-linking reaction can further improve the cross-linking network in later stages, thereby improving the overall cross-linking efficiency, shortening the processing cycle, and optimizing the overall material performance. Figure 2 The figure shows a comparison of the thermal conductivity of cross-linked polyethylene insulation materials in Examples 1 to 9. It can be seen that the cross-linked polyethylene insulation material in Example 6 has the highest thermal conductivity.

[0093] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A cross-linked polyethylene insulation material raw material composition, characterized in that, It comprises the following components by weight: 97-99 parts polyethylene, 0.9-1.7 parts crosslinking agent, 0.2-0.5 parts crosslinking aid, and 0.1-0.3 parts antioxidant; The polyethylene has a molecular weight distribution of 4.0 to 6.0 PDI.

2. The cross-linked polyethylene insulation material raw material composition according to claim 1, characterized in that, The polyethylene has a molecular weight distribution of 4.5–5.5 PDI.

3. The cross-linked polyethylene insulation material raw material composition according to claim 1, characterized in that, The specific heat capacity of the polyethylene is 2.0 to 2.5 J / (g·℃).

4. The cross-linked polyethylene insulation material raw material composition according to claim 1, characterized in that, The specific heat capacity of the polyethylene is 2.44–2.46 J / (g·℃).

5. The cross-linked polyethylene insulation material raw material composition according to claim 1, characterized in that, The crosslinking agent is one or more of dicumyl peroxide and bis-tert-butyl peroxide.

6. The cross-linked polyethylene insulation material raw material composition according to claim 5, characterized in that, The crosslinking agent is obtained by mixing dicumyl peroxide and bis-tert-butyl peroxide in a 4:1 ratio.

7. The cross-linked polyethylene insulation material raw material composition according to claim 1, characterized in that, The crosslinking aid is one or more of triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, and polytrilyl isocyanurate.

8. The cross-linked polyethylene insulation material raw material composition according to claim 1, characterized in that, The antioxidant is one or more of antioxidant 300, antioxidant 1010, antioxidant 168, antioxidant 1035, and antioxidant DLTP.

9. The cross-linked polyethylene insulation material raw material composition according to claim 8, characterized in that, The antioxidant is obtained by mixing antioxidant 300, antioxidant 1010 and antioxidant 168 in a ratio of 1:1:

1.

10. The cross-linked polyethylene insulation material raw material composition according to claim 1, characterized in that, It includes the following components in parts by weight: 98 parts polyethylene, 0.96 parts dicumyl peroxide 0.24 parts of di-tert-butylperoxide diisopropylbenzene, 0.3 parts crosslinking aid, 0.5 parts antioxidant.

11. A method for preparing a cross-linked polyethylene insulating material, characterized in that, Includes the following steps: According to the proportion of the raw material composition described in any one of claims 1 to 10, polyethylene and antioxidant are weighed and blended at high speed to obtain a compound base material; The compound base material is mixed and extruded in a mixer, then granulated underwater and dehydrated to obtain insulating granules. The insulating granules are heated and dried, and then a uniformly blended crosslinking agent and crosslinking aid are added. After mixing and drying, the mixture is kept warm and absorbed to obtain the crosslinked polyethylene insulating material.

12. The preparation method according to claim 11, characterized in that, The extrusion temperature is 120℃~180℃.

13. The preparation method according to claim 11, characterized in that, During the extrusion process, the outlet pressure is ≤0.4MPa and the torque fluctuation is ≤0.7N·m.

14. The preparation method according to claim 11, characterized in that, The insulating material granules are heated and dried, and then sprayed with a crosslinking agent and crosslinking aid that are uniformly mixed at 55-65°C. The mixing system rotates at 2-8 rpm, and after mixing and drying, the mixture is kept warm and absorbed.

15. The preparation method according to claim 11, characterized in that, The heat preservation and absorption time is 6 to 10 hours, and the temperature is 50℃ to 70℃.

16. A cross-linked polyethylene insulating material, characterized in that, It is prepared using the method for preparing cross-linked polyethylene insulating material according to any one of claims 11 to 15.

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