Modified insulating master batch particle for high-voltage rubber cable insulation and preparation method of modified insulating master batch particle

Abstract

The preparation method comprises the following steps: firstly, putting a silane coupling agent into a round-bottom flask, then adding absolute ethyl alcohol, heating, enabling the coupling agent to actively perform alcoholysis in the absolute ethyl alcohol in advance to form a silanol compound, then adding acetic acid to adjust the pH value to be acidic, so as to prepare an acidic alcoholysis pretreatment solution, and then adding the acidic alcoholysis pretreatment solution into the round-bottom flask; then spraying the pretreatment liquid into a mixture containing premixed linear low-density polyethylene, modified calcined kaolin and zinc stearate, and mixing, extruding and granulating to prepare the modified insulating master batch particles. When the modified insulating master batch particles are applied to high-voltage rubber cable insulation, gel and powder agglomeration can be greatly reduced, the water absorption of materials is reduced, the cleanness of a production environment is kept, the master batch production process is short, simple and feasible, can be realized only by common industrial equipment, is suitable for mass production, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a modified insulating masterbatch for high-voltage rubber cable insulation and a preparation method thereof. Background Art

[0002] The voltage level requirement for wind turbine cables is 66kV. The cable insulation material should use vulcanized EPDM rubber as the insulation material (EPR or HEPR type). Due to the material properties and complex components, vulcanized EPDM rubber is usually only used in medium and low voltage cables. 66kV EPDM rubber cable is the highest level of rubber-sheathed cable application in China, and the requirements for insulation materials are greatly improved. The insulation material is required to have high dispersion uniformity, insulation performance and cleanliness. However, due to the high molecular weight of rubber materials, many types of additives are required. Compared with plastic insulation such as XLPE, it is difficult to process and it is difficult to achieve uniform dispersion. Therefore, it is not easy to obtain high-cleanliness products. For a long time, there has been a great demand for 35kV EPDM rubber insulation.

[0003] In recent years, 35kV EPDM insulation has gradually been widely used, but there are few high-quality 66kV EPDM insulation commercial products, which are urgently needed to meet the rapid development of high-voltage wind power cables. To obtain high-quality high-voltage EPDM insulation materials, special raw materials, formulas and processes are required, especially in terms of process requirements. Ordinary processes have great risks. The insulation materials currently used in China all follow the 10-35kV insulation material production method. The large-scale use of powder feeding is prone to uneven dispersion, and the largest amount of powder is kaolin. To improve the insulation quality, the first task is to improve its quality and dispersion uniformity. The dispersion uniformity of kaolin is a major challenge. Because it is an inorganic powder with a small particle size, it is difficult to disperse it evenly in rubber by physical mixing. In order to meet the needs of large-scale industrial production, coupling agents are usually added directly during the mixing process. The problem is that a small amount of coupling agent added to a multi-component powder will be quickly absorbed by a small part of the powder, and most of the powder is not actually wetted by the coupling agent. The coupling modification effect is very poor and may even cause the powder to agglomerate. Even if the spraying method is used, there is a risk of easy agglomeration. It is difficult to obtain a uniformly dispersed rubber compound, and it is impossible to ensure that a high-cleanliness insulation material is obtained. This poses a great safety hazard to high-voltage cables.

[0004] In addition, in order to facilitate use and introduce as few other polymers and additives as possible, it is necessary to prepare masterbatch with a high effective content. However, the high content of masterbatch is also a major challenge to the wetting and dispersion of the powder, which requires a significant increase in the adhesion of modified additives such as coupling agents.

[0005] Chinese patent application No. 202311762385.0 discloses a preparation method and application of coupled modified carbon black for plastics, which belongs to the field of online production and modification technology of carbon black. It does not involve the modification treatment of insulating powder, and it still belongs to physical mixing and does not involve chemical reaction process. It cannot be applied to high-voltage rubber cable insulation.

[0006] Chinese patent application numbers 201510880334.7 and 201910890996.0 respectively disclose modified plastic masterbatches, which are essentially modified plastics with low powder content, different from modified insulating powders.

[0007] Therefore, in order to obtain high-quality high-voltage EPDM insulation materials, it is necessary to study special raw materials, formulas and processes. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a modified insulating masterbatch for high-voltage rubber cable insulation and a preparation method thereof. The modified insulating masterbatch comprises the following steps: firstly placing a silane coupling agent in a round-bottom flask, then adding anhydrous ethanol and heating the mixture, so that the coupling agent is actively pre-alcoholized in the anhydrous ethanol to form a silanol compound, then adding acetic acid to adjust the pH to acidic, thereby preparing an acidic alcoholysis pretreatment liquid, and then spraying the pretreatment liquid into a mixture of pre-mixed linear low-density polyethylene, modified calcined kaolin and zinc stearate, and then mixing, extruding and granulating the mixture to prepare the modified insulating masterbatch.

[0009] The technical solution of the present invention is as follows: A modified insulating masterbatch for high-voltage rubber cable insulation, wherein the modified insulating masterbatch is used to modify kaolin powder by using a pretreatment liquid formed by active alcoholysis of a coupling agent to achieve secondary modification of the powder material. The essence of the modified masterbatch is that the silicon-oxygen bond (Si-O) in the silane molecule is easily attacked by protons and broken under acidic conditions, and silicate ions and corresponding organic groups are generated at the same time. This decomposition reaction can connect the organic groups in the silane coupling agent with the hydroxyl groups or other functional groups on the surface of the inorganic powder, thereby improving its adhesion to the powder material. The treatment method involves physical mixing and chemical reaction, and at the same time, in the preparation process, the modified masterbatch is used to modify the kaolin powder. The spraying method is used in the preparation process to increase the contact area between the coupling agent and the powder, greatly improve the utilization rate of the coupling agent, and improve the interface contact between the coupling agent and the powder, which is a qualitative improvement for the uniform dispersion of the powder, thereby further ensuring the uniformity of the material in subsequent applications, reducing the generation of gel and agglomeration, and reducing the water absorption of the insulating material. It can also avoid the dust caused by the use of a large amount of powder materials in the production process, and improve the wetting effect of kaolin. The process flow used in this modification method is short, simple and easy, and can be achieved using only common industrial equipment. It is suitable for mass production and has good application prospects.

[0010] The present invention also provides a method for preparing the modified insulating masterbatch for high-voltage rubber cable insulation. First, a silane coupling agent is placed in a round-bottom flask equipped with a heating jacket and a stirrer, then anhydrous ethanol is added to dilute and gradually alcoholyze to form silanol, and then acetic acid is added to adjust the pH to acidic to prepare an acidic alcoholysis pretreatment liquid, and then linear low-density polyethylene, zinc stearate, and calcined kaolin are put into an internal mixer and sprayed with the pretreatment liquid, and after uniform mixing, the mixture is extruded and granulated to prepare the modified insulating masterbatch. The core of the present invention is to pre-actively alcoholize the coupling agent in an acidic environment, thereby greatly improving the adhesion of the coupling agent molecules to the surface of the inorganic powder, improving the interface effect between the coupling agent and the insulating powder, and further improving the wettability and dispersibility of the powder. The dust pollution in the production environment is reduced by master batching, so that the linear low-density polyethylene macromolecules can cover the inorganic powder to the greatest extent, forming a highly uniform and consistent modified insulating mixture with low interface efficiency, greatly reducing the adsorption of water molecules by the exposed hydrophilic groups of the inorganic powder, reducing the water absorption rate, and facilitating the formation of highly uniform and consistent high-quality insulating materials in the subsequent mixing process.

[0011] The purpose of the present invention is achieved through the following technical solutions: A modified insulating masterbatch for high-voltage rubber cable insulation is made of the following components by weight: 10-20 parts of linear low-density polyethylene, 2-5 parts of pretreatment liquid, 60-80 parts of modified calcined kaolin, 0.01-0.1 parts of zinc stearate; The effective content of modified calcined kaolin accounts for 60-80% of the total mass of modified insulating masterbatch; The pretreatment liquid is prepared by 0.2-1 parts of silane coupling agent, 2-5 parts of anhydrous ethanol and 0.1-0.5 parts of acetic acid in parts by mass.

[0012] The modified insulating masterbatch for high-voltage rubber cable insulation has the following properties: Maximum torque MH 1.23-1.335, hardness ShoreA 78-82, Mooney viscosity at 100℃ 51.7-52.3, tensile strength 11.1-12.2 Mpa, elongation at break 352-366%, permanent deformation after break 48-54%; After air heat aging at 150℃×168h: The change rate of tensile strength is 3-8%, and the change rate of elongation at break is -9~-13%; Thermal stretching (250℃×15min×0.2N / mm 2 ): Elongation 5-10%, permanent deformation after cooling 0-3%, average breakdown field strength 34-36 kV / mm, The average volume resistivity at 20℃ is 3.3×1016 ~4.8×10 16 Ω.cm, 90℃ volume resistivity average value 2.3×10 16 ~4.5×10 16 Ω.cm, 85℃×336h water absorption test (gravimetric method) 0.3-1.1 mg / cm 2 .

[0013] Furthermore, preferably, the effective content of the modified calcined kaolin in the modified insulating masterbatch particles accounts for 75%-80% of the total mass of the modified insulating masterbatch particles.

[0014] Furthermore, the modified calcined kaolin is kaolin that has been purified by high-temperature calcination and surface-coupled modified, with an average particle size of <2 μm and a 325-mesh sieve residue of <0.02%.

[0015] Furthermore, as a preference, the modified calcined kaolin is selected from one or a mixture of Translink37, Translink77 and Translink445 (formerly kaolin produced by BASF of Germany) produced by KaMin Company of the United States, and the mixture can be in any proportion.

[0016] Further, as a preference, the coupling agent is one or a combination of vinyl dimethyl silane and vinyl triethoxy silane, which can be mixed in any proportion; specifically, it is one or a combination of two selected from A171, A172, KH-550, KH560, KH570, and si-69.

[0017] The present invention also relates to a method for preparing the modified insulating masterbatch for high-voltage rubber cable insulation, comprising the following steps: (1): According to the following proportion, weigh 0.2-0.5 kg of anhydrous ethanol and add it to a 2000 mL round-bottom flask. The flask is equipped with a heating jacket on the outside and connected to a stirrer, a temperature measuring device and a cooling reflux device. Slowly add 0.02-0.1 kg of silane coupling agent while stirring with a stirrer. The stirrer speed is 1000-1500 r / min. Turn on the electric heating and keep the temperature of the mixed solution at 70-80°C. Stir for 30 minutes, then slowly add 0.01-0.05 kg of acetic acid to adjust the pH to 4-5.5 to obtain a pretreatment solution; (2): According to the following proportions, weigh 10-20 kg of linear low-density polyethylene, 60-80 kg of modified calcined kaolin (added in 3-4 times), and 0.01-0.1 kg of zinc stearate and put them into a 75L internal mixer at a temperature of 120-130°C. Spray the pretreatment liquid obtained in step (1) while mixing. Keep the rotor speed of the internal mixer at 25-38 r / min. After mixing evenly, feed the mixture into a single-screw extruder granulator. After granulation, cool to room temperature to finally obtain modified insulating masterbatch.

[0018] Furthermore, in step (2), the pellets are finally granulated and cooled by a pelletizing machine head to obtain a columnar modified insulating masterbatch having a size of (2-3 mm)×(2-3 mm).

[0019] Compared with the prior art, the present invention has the following advantages: 1. The method for preparing a modified insulating masterbatch for high-voltage rubber cable insulation of the present invention is to modify kaolin powder by a pre-treatment liquid formed by active alcoholysis of a coupling agent in advance through physical mixing and chemical reaction to achieve secondary modification of the powder material. Its essence is that the silicon-oxygen bond (Si-O) in the silane molecule is easily attacked by protons and broken under acidic conditions, and silicate ions and corresponding organic groups are generated at the same time. This decomposition reaction can connect the organic groups in the silane coupling agent with the hydroxyl groups or other functional groups on the surface of the inorganic powder, thereby improving its adhesion to the powder material.

[0020] 2. The method for preparing a modified insulating masterbatch for high-voltage rubber cable insulation described in the present invention increases the contact area between the coupling agent and the insulating powder by acidic alcoholysis of the pretreatment liquid and spraying, greatly improves the utilization rate of the coupling agent, improves the interface contact between the coupling agent and the powder, and improves the wetting effect of kaolin, which is a qualitative improvement for the uniform dispersion of the powder, thereby further ensuring the uniformity of the material in subsequent applications, reducing the generation of gel and agglomeration, and reducing the water absorption of the insulating material. It can also avoid dust caused by the use of a large amount of powder material in the production process, which is beneficial to the uniform dispersion of the insulating material and improves product consistency.

[0021] 3. The method for preparing a modified insulating masterbatch for high-voltage rubber cable insulation described in the present invention has a short process flow, is simple and easy to implement, can be implemented using only common industrial equipment, is suitable for mass production, and has good application prospects.

[0022] 4. The modified insulating masterbatch for high-voltage rubber cable insulation prepared by the present invention can obtain the modified insulating masterbatch with very high insulating powder content by using the modification method, thereby reducing the amount of other polymers and additives used, and is conducive to the production of higher quality high-voltage rubber cable insulation materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a graph comparing the number of gels per 1000g of insulating rubber material in the experimental examples of the present invention and the comparative examples (M1, M2, M3, respectively representing Example 1, Example 2, and Example 3). DETAILED DESCRIPTION

[0024] The present invention is further described in detail below by way of examples, but these examples should not be considered as limiting the present invention.

[0025] Embodiment 1: A modified insulating masterbatch for high-voltage rubber cable insulation, comprising the following components by mass: 13 parts of linear low-density polyethylene, 2.5 parts of pretreatment liquid, 62 parts of modified calcined kaolin (Trinslink37), and 0.03 parts of zinc stearate; The effective content of modified calcined kaolin in the modified insulating masterbatch particles accounts for 80% of the total mass of the masterbatch; The pretreatment solution contains the following components by mass: 0.25 parts of silane coupling agent (A172), 2.17 parts of anhydrous ethanol, and 0.08 parts of acetic acid; The specific preparation method is as follows: (1) 217 ​​g of anhydrous ethanol was weighed according to the ratio and added into a 2000 mL round-bottom flask. A heating jacket was installed on the outside of the flask, and a stirrer, a temperature measuring device and a cooling reflux device were connected inside. 25 g of a silane coupling agent was slowly added while stirring with the stirrer. The stirrer speed was 1000 r / min. The electric heating was turned on and the temperature of the mixed solution was kept at 70° C. After stirring for 30 min, 8 g of acetic acid was slowly added to adjust the pH to 5.1 to obtain a pretreatment solution; (2) 13 kg of linear low-density polyethylene, 62 kg of modified calcined kaolin (added in 3-4 times) and 0.03 kg of zinc stearate were weighed according to the ratio and put into a 75L internal mixer at a temperature of 120°C, and the pretreatment liquid was sprayed while mixing. The rotor speed of the internal mixer was maintained at 28 r / min. After mixing evenly, the materials were fed into a single-screw extruder granulator, and after granulation, they were cooled to room temperature to finally obtain modified insulating masterbatch; (3) After granulation and cooling by a granulator head, columnar modified insulating masterbatch particles with a size of 3 mm*3 mm are obtained.

[0026] Embodiment 2: A modified insulating masterbatch for high-voltage rubber cable insulation, comprising the following components by mass: 16.5 parts of linear low-density polyethylene, 2.8 parts of pretreatment liquid, 70 parts of modified calcined kaolin (Translink37 and Translink77 mixed at a ratio of 2:1), and 0.05 parts of zinc stearate; The effective content of modified calcined kaolin in the modified insulating masterbatch particles accounts for 78.3% of the total mass of the masterbatch; The pretreatment solution contains the following components by mass: 0.35 parts of silane coupling agent (A172 and KH550 mixed at a ratio of 1:1), 2.6 parts of anhydrous ethanol, and 0.12 parts of acetic acid; The specific preparation method is as follows: (1) 260 g of anhydrous ethanol was weighed according to the ratio and added into a 2000 mL round-bottom flask. A heating jacket was installed on the outside of the flask, and a stirrer, a temperature measuring device and a cooling reflux device were connected inside. 35 g of a silane coupling agent was slowly added while stirring with the stirrer. The stirrer speed was 1300 r / min. The electric heating was turned on and the temperature of the mixed solution was kept at 75° C. After stirring for 30 min, 12 g of acetic acid was slowly added to adjust the pH to 4.6 to obtain a pretreatment solution; (2) 16.5 kg of linear low-density polyethylene, 70 kg of modified calcined kaolin (added in 3-4 times), and 0.05 kg of zinc stearate were weighed according to the ratio and put into a 75L internal mixer at a temperature of 125°C. 2.8 kg of pretreatment liquid was sprayed while mixing. The rotor speed of the internal mixer was maintained at 31 r / min. After mixing evenly, the materials were fed into a single-screw extruder granulator. After granulation, they were cooled to room temperature to finally obtain modified insulating masterbatch; (3) After granulation and cooling by a granulator head, columnar modified insulating masterbatch particles with a size of 2.5 mm*2.5 mm are obtained.

[0027] Embodiment 3: A modified insulating masterbatch for high-voltage rubber cables, comprising the following components by mass: 20 parts of linear low-density polyethylene, 3.1 parts of pretreatment liquid, 75 parts of modified calcined kaolin, and 0.08 parts of zinc stearate; The effective content of modified calcined kaolin in the modified insulating masterbatch particles accounts for 77.1% of the total mass of the masterbatch; The pretreatment solution comprises the following components by weight: 0.4 parts of silane coupling agent, 2.52 parts of anhydrous ethanol, and 0.18 parts of acetic acid; The specific preparation method is as follows: (1) 252 g of anhydrous ethanol was weighed according to the ratio and added into a 2000 mL round-bottom flask. A heating jacket was installed on the outside of the flask, and a stirrer, a temperature measuring device and a cooling reflux device were connected inside. 40 g of a silane coupling agent was slowly added while stirring with the stirrer. The stirrer speed was 1300 r / min. The electric heating was turned on and the temperature of the mixed solution was kept at 75° C. After stirring for 30 min, 18 g of acetic acid was slowly added to adjust the pH to 4.1 to obtain a pretreatment solution; (2) Weigh 20 kg of linear low-density polyethylene, 75 kg of modified calcined kaolin (added in 3-4 times), and 0.08 kg of zinc stearate according to the ratio and put them into a 75L internal mixer at a temperature of 128°C. Spray 3.1 kg of pretreatment liquid while mixing. Keep the rotor speed of the internal mixer at 33 r / min. After mixing evenly, feed the materials into a single-screw extruder granulator. After granulation, cool to room temperature to finally obtain modified insulating masterbatch. (3) After granulation and cooling by a granulator head, columnar modified insulating masterbatch particles with a size of 3 mm*3 mm are obtained.

[0028] Experimental example: The performance test of the modified insulating masterbatch prepared by the present invention is as follows: According to the ratio of Examples 1-3, three kinds of modified insulating masterbatches M1, M2 and M3 were prepared respectively. According to the formula of high-voltage insulating material, the insulating powder and coupling agent therein were replaced by the three kinds of masterbatches respectively, and then the cable insulating material was made under the same mixing conditions and vulcanized on a molding machine. The molding machine had a working pressure of 12 MPa and a temperature of 170°C. After pressing for 12 minutes, the dumbbell-shaped test sample, volume resistivity test sample and breakdown strength test sample with a thickness of 1 mm were obtained. The physical properties of the corresponding samples were tested according to GB / T528, the hot elongation was tested according to 2951.18, the hardness was tested according to the national standard GB / T 531, the volume resistivity at room temperature and high temperature was tested according to GB / T 3048, the breakdown field strength was tested according to GB / T 1408, the water absorption was tested according to GB / T 2951.13, and the unvulcanized rubber was taken and tested using a torque Mooney viscosity tester according to GB / T 1232 to obtain the Mooney viscosity; Comparative Example 1 is an insulating material prepared by directly mixing powder and coupling agent and pressing into sheets; Comparative Example 2 is an insulating material prepared by simply spraying a coupling agent and preparing a masterbatch; The material types and weights of all the above alternatives are consistent, and the specific test results are shown in Table 1: Table 1 Performance test of prepared modified insulating masterbatch

[0029] From the above results, we can see that: 1. By comparing Examples 1-3 with Comparative Examples 1-2, the maximum torque of the high-voltage cable insulation mixture prepared by the present invention is increased to varying degrees compared with the comparative examples, and the Mooney viscosity is slightly increased. The substantial increase in tensile strength, slight decrease in elongation, and reduction in permanent deformation indicate that the use of modified insulating masterbatch can effectively increase the degree of crosslinking of the rubber material, and a large amount of inorganic powder is effectively dispersed and coated, thereby obtaining better physical and mechanical properties, and the aging resistance is greatly improved; 2. The insulating material prepared by the method for preparing a modified insulating masterbatch for high-voltage rubber cable insulation of the present invention has significantly improved breakdown field strength and volume resistivity at room temperature and high temperature, especially the high-temperature volume resistivity changes very little, indicating that the electrical properties are better and more stable at high temperatures. The electrical properties are directly related to the content of material impurities (generally coke and irreversible gel, coke and the enrichment of vulcanizing agent, gel and the dispersion of inorganic powder), which also shows that the insulating material prepared by the present invention has higher dispersion and cleanliness; 3. In addition, it can be seen from the above water absorption test data that the insulating material prepared by the present invention has a greatly reduced water absorption, which means that there are fewer free hydrophilic groups in the mixture, and most of the hydrophilic groups are coated by rubber molecules, so it exhibits excellent hydrophobicity. Furthermore, the surface powder material has good wettability and good dispersibility.

[0030] 4. The applicant uses an optical control system to test the amount of impurities in the material film. The transmittance is measured by scanning the film surface with a high-precision electronic camera, and the system automatically distinguishes suspected char or gel based on the transmittance. Char appears as black impurities with basically no transmittance; gel appears to be permeable but with abnormal transmittance, and particles that are yellow or have the potential to further develop into char are judged to be gel points. Several materials did not have char or impurities greater than or equal to 50μm when tested on thin films. The gel point of each material was further tested. The gel point has the risk of further developing into char, which can reflect the potential safety risks of each material. The specific test results are as follows: Figure 1 As shown: Figure 1 : Comparison of the number of gels per 1000g of insulating rubber; according to Figure 1 It can be seen from the change graph of the number of gels that the number of gels per kilogram of the high-voltage insulating material prepared using the modified insulating masterbatch particles of the present invention is greatly reduced, indicating that the powder in the rubber is more evenly dispersed, has higher purity than the comparison material, and has higher consistency.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A modified insulating masterbatch for high voltage rubber cable insulation, characterized in that: By mass, it is made of the following components: 10-20 parts of linear low-density polyethylene, 2-5 parts of pretreatment liquid, 60-80 parts of modified calcined kaolin, 0.01-0.1 parts of zinc stearate; The effective content of modified calcined kaolin accounts for 60-80% of the total mass of modified insulating masterbatch; The pretreatment liquid is prepared by 0.2-1 parts of silane coupling agent, 2-5 parts of anhydrous ethanol and 0.1-0.5 parts of acetic acid in parts by mass.

2. The modified insulating masterbatch for high-voltage rubber cable insulation according to claim 1 is characterized in that: The effective content of the modified calcined kaolin in the modified insulating masterbatch particles accounts for 75%-80% of the total mass of the modified insulating masterbatch particles.

3. The modified insulating masterbatch for high-voltage rubber cable insulation according to claim 1 is characterized in that: The modified calcined kaolin is kaolin that is purified by high-temperature calcination and surface-coupled modified, with an average particle size of less than 2 μm and a 325-mesh sieve residue of less than 0.02%.

4. The modified insulating masterbatch for high-voltage rubber cable insulation according to claim 3 is characterized in that: The modified calcined kaolin is selected from one or a mixture of Translink37, Translink77 and Translink445 produced by KaMin Company of the United States, and the mixture can be in any proportion.

5. The modified insulating masterbatch for high-voltage rubber cable insulation according to claim 1 is characterized in that: The coupling agent is one of vinyl dimethyl silane and vinyl triethoxy silane or a combination of the two, and the mixture can be in any proportion.

6. The modified insulating masterbatch for high-voltage rubber cable insulation according to claim 1, characterized in that: The coupling agent is selected from one or a combination of two of A171, A172, KH-550, KH560, KH570, and si-69.

7. A method for preparing a modified insulating masterbatch for high-voltage rubber cable insulation according to any one of claims 1 to 5, characterized in that: The modified insulating masterbatch for high-voltage rubber cable insulation has the following properties: Maximum torque MH 1.23-1.335, hardness ShoreA 78-82, Mooney viscosity at 100℃ 51.7-52.3, tensile strength 11.1-12.2 Mpa, elongation at break 352-366%, permanent deformation after break 48-54%; After air heat aging at 150℃×168h: The change rate of tensile strength is 3-8%, and the change rate of elongation at break is -9~-13%; Thermal stretching 250℃×15min×0.2N / mm 2 : Elongation 5-10%, permanent deformation after cooling 0-3%, average breakdown field strength 34-36 kV / mm, The average volume resistivity at 20℃ is 3.3×10 16 ~4.8×10 16 Ω.cm, 90℃ volume resistivity average value 2.3×10 16 ~4.5×10 16 Ω.cm, 85℃×336h water absorption test, gravimetric method 0.3-1.1 mg / cm 2 .

8. The method for preparing a modified insulating masterbatch for high-voltage rubber cable insulation according to claim 1, characterized in that: The following steps are involved: (1): According to the following proportion, weigh 0.2-0.5 kg of anhydrous ethanol and add it to a 2000 mL round-bottom flask. The flask is equipped with a heating jacket on the outside and connected to a stirrer, a temperature measuring device and a cooling reflux device. Slowly add 0.02-0.1 kg of silane coupling agent while stirring with a stirrer. The stirrer speed is 1000-1500 r / min. Turn on the electric heating and keep the temperature of the mixed solution at 70-80°C. Stir for 30 minutes, then slowly add 0.01-0.05 kg of acetic acid to adjust the pH to 4-5.5 to obtain a pretreatment solution; (2): According to the following proportions, weigh 10-20 kg of linear low-density polyethylene and 60-80 kg of modified calcined kaolin, add them in 3-4 portions, and add 0.01-0.1 kg of zinc stearate into a 75L internal mixer at a temperature of 120-130°C. Spray the pretreatment liquid obtained in step (1) while mixing. Keep the rotor speed of the internal mixer at 25-38 r / min. After mixing evenly, feed the mixture into a single-screw extruder granulator. After granulation, cool to room temperature to finally obtain modified insulating masterbatch.

9. The method for preparing a modified insulating masterbatch for high-voltage rubber cable insulation according to claim 8, characterized in that: In step (2), the columnar modified insulating masterbatch with a size of (2-3 mm)×(2-3 mm) is obtained by granulating and cooling the masterbatch through a granulator head.

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