Preparation method of cable insulating material

Abstract

The invention discloses a cable insulation material preparation method, which comprises: S1, pre-mixing modified nanoparticles and epoxidized soybean oil to form a mixture; s2, 30 to 50 parts of mixed resin, 15 to 20 parts of a mixture, 0.1 to 0.4 part of an antioxidant, 0.2 to 0.6 part of a cross-linking agent and 1 to 2 parts of a toughening agent are weighed; s3, respectively adding the mixed resin, the mixture, the antioxidant, the cross-linking agent and the flexibilizer into a double-screw extruder, and carrying out partitioned temperature control to obtain a molten resin matrix. The invention belongs to the technical field of cable insulation material preparation, and aims to solve the problems that in the prior art, the intermolecular toughness is relatively small, so that the cable insulation material becomes more brittle, and the cable insulation material is easy to crack during bending. The cable insulation material has the technical effects that the intermolecular toughness of the cable insulation material can be remarkably improved, and then the problems that the brittleness is increased and the cable insulation material is easy to crack when being bent due to large internal stress generated in the cable insulation material can be effectively avoided.

Description

Technical Field

[0001] This application belongs to the technical field of cable insulation material preparation, and specifically relates to a method for preparing a cable insulation material. Background Art

[0002] With the acceleration of urban construction, the expansion of production and manufacturing scale, and the sharp increase in electricity demand in human daily work and life, ensuring the stable and efficient operation of the power system has become particularly crucial. As an indispensable part of the cable structure, the performance and quality of cable insulation materials are directly related to the stability and reliability of the power system.

[0003] The cable insulation material tightly wraps the conductor of the wire and cable, and its main function is to effectively resist wear, oxidation, and other external environmental factors. High-quality cable insulation materials can significantly reduce the risk of insulation damage and faults, providing strong guarantee for the continuous and stable operation of the power system. At the same time, it can also effectively reduce the loss of electricity during transmission, improve the energy efficiency level of power equipment, and enhance the safety of the system.

[0004] However, at present, in the preparation process of most cable insulation materials, in order to improve the insulation performance, chemical groups are introduced into the cable insulation materials or cross-linking treatment is carried out. Although the overall heat resistance and mechanical properties of the cable insulation materials are improved, the activity ability between molecular chains is reduced, and the toughness between molecules is small, resulting in the cable insulation materials becoming more brittle and being prone to cracking when bent. Summary of the Invention

[0005] This application provides a method for preparing a cable insulation material, aiming to solve the problem in the prior art that the toughness between molecules is small, resulting in the cable insulation material becoming more brittle and being prone to cracking when bent.

[0006] A method for preparing a cable insulation material, the method comprising the following steps:

[0007] S1: Pre-mix the modified nanoparticles and epoxidized soybean oil to form a mixture;

[0008] S2: Weigh 30 - 50 parts of mixed resin, 15 - 20 parts of the mixture, 0.1 - 0.4 parts of antioxidant, 0.2 - 0.6 parts of cross-linking agent, and 1 - 2 parts of toughening agent;

[0009] S3: Add the mixed resin, the mixture, the antioxidant, the cross-linking agent, and the toughening agent into a twin-screw extruder respectively, and control the temperature in zones to obtain a molten resin matrix;

[0010] S4: Inject the cross-linking agent at the end of the twin-screw extruder, so that the cross-linking agent and the molten resin matrix complete the cross-linking reaction synchronously in the twin-screw extruder to form a cross-linked matrix, and extrude to form a continuous strip-shaped cable insulation material;

[0011] S5: Gradually cool the extruded strip-shaped cable insulation material by means of gradient cooling.

[0012] Furthermore, the mass ratio of the modified nanoparticles to epoxidized soybean oil is 1-2:2.5-5. Epoxidized soybean oil serves as a dispersion medium to prevent the agglomeration of the modified nanoparticles, and the modified nanoparticles are modified nano boron nitride particles.

[0013] Furthermore, the mixed resin is low-density polyethylene and ethylene-butyl acrylate copolymer, and the mass ratio of low-density polyethylene to ethylene-butyl acrylate copolymer is 4-8:1-2.5.

[0014] Furthermore, the specific steps of S3 are as follows:

[0015] S3.1: First, add the mixed resin to the main feeding port of the twin-screw extruder simultaneously, control the temperature of the main feeding port at 110-160°C, and the screw speed at 220-250 rpm simultaneously.

[0016] S3.2: Add the toughening agent to the mixed resin through the first side feeding port, control the temperature of the first side feeding port to be the same as that of the main feeding port, and the screw speed at 180-200 rpm.

[0017] S3.3: Inject the mixture and the antioxidant into the twin-screw extruder through the second side feeding port together to obtain a molten resin matrix.

[0018] Furthermore, the screw speed at the main feeding port is 220 rpm, the screw speed at the first side feeding port is 180 rpm, and the screw speed at the second side feeding port is 250 rpm.

[0019] Furthermore, the specific steps of S4 are as follows:

[0020] S4.1: Set a liquid injection pump at the end of the twin-screw extruder, and inject the crosslinking agent in liquid form into the twin-screw extruder through the liquid injection pump to make the crosslinking agent evenly dispersed in the molten resin matrix.

[0021] S4.2: Detect the torque change of the crosslinked matrix through an on-line rheometer to indirectly reflect the degree of crosslinking.

[0022] S4.3: Preset that the degree of crosslinking deviates from the set range. If it is detected that the degree of crosslinking deviates from the set range, automatically adjust the injection rate of the crosslinking agent and the screw speed.

[0023] S4.4: Extrude the crosslinked matrix through the die head of the twin-screw extruder to form a continuous strip-shaped cable insulation material.

[0024] Furthermore, the specific steps of S5 are as follows:

[0025] S5.1: Set the initial cooling temperature and the temperature reduction range of the water cooling device; the initial cooling temperature is 60 - 75 °C, and the temperature reduction range is to reduce 5 - 8 °C every 10 - 15 minutes until it drops to 15 - 20 °C;

[0026] S5.2: Preset the flow rate of the cooling medium of the water cooling device to be 0.5 - 1.5 m 3 / h, and the flow rate of the cooling medium decreases by 0.1 - 0.2 m 3 / h every 10 - 15 minutes;

[0027] S5.3: Feed the extruded strip-shaped cable insulating material into the water cooling device so that it enters the cooling medium to complete the cooling.

[0028] Furthermore, the main feeding port is the first temperature control area, the first side feeding port is the second temperature control area, and the second side feeding port is the third temperature control area.

[0029] Furthermore, the temperature of the first temperature control area is 110 - 160 °C, the temperature of the second temperature control area is the same as that of the first temperature control area, and the third temperature control area is 150 - 185 °C.

[0030] Furthermore, the injection rate of the liquid injection pump is 3 - 7 mL / min, and the injection pressure is 0.5 - 1.0 MPa. Compared with the prior art, the present application has at least the following beneficial effects:

[0031] Based on the further analysis and research of the problems in the prior art, the present application adds an appropriate amount of toughening agent. With its excellent elastomer properties, the toughening agent can significantly improve the intermolecular toughness of the cable insulating material, making it more resistant to external force impact. At the same time, combined with the optimization of the preparation method process, the gradient cooling method is used to gradually cool the extruded strip-shaped cable insulating material to reduce the generation of internal stress. In addition, controlling the cooling rate can change the crystallinity of the cable insulating material, thereby affecting its anti-bending performance, and further effectively avoiding the problems of large internal stress generated inside the cable insulating material, resulting in increased brittleness and easy cracking during bending. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic flow chart of a preparation method of a cable insulating material provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments.

[0034] A preparation method of a cable insulating material provided by the present application includes the following steps:

[0035] S1: Pre-mix the modified nanoparticles and epoxidized soybean oil to form a mixture. The pre-mixing equipment is an ultrasonic disperser, and the dispersion time is 15 - 45 minutes;

[0036] Among them, the mass ratio of the modified nanoparticles to the epoxidized soybean oil is 1 - 2:2.5 - 5. The epoxidized soybean oil serves as a dispersion medium to prevent the aggregation of the modified nanoparticles;

[0037] The modified nanoparticles are modified nano - boron nitride particles. The dispersion in the polymer matrix is one of the key factors affecting the performance of the composite cable insulation material. The modified nano - boron nitride particles can improve their dispersion in the polymer matrix through appropriate surface modification treatment, enabling them to be more evenly dispersed in the cable insulation material. This helps to improve the overall performance of the composite cable insulation material and reduce the performance degradation caused by the aggregation of the nano - cable insulation material.

[0038] The epoxidized soybean oil is used to improve the processing performance of the cable insulation material, reducing the melting temperature and the viscosity of the molten resin matrix.

[0039] The ultrasonic cavitation effect breaks the van der Waals force between the modified nanoparticles to ensure a monodisperse state;

[0040] S2: Weigh 30 - 50 parts of the mixed resin, 15 - 20 parts of the mixture, 0.1 - 0.4 parts of the antioxidant, 0.2 - 0.6 parts of the cross - linker, and 1 - 2 parts of the toughening agent;

[0041] Among them, the mixed resin is low - density polyethylene (LDPE) and ethylene - butyl acrylate copolymer (EBA), and the mass ratio of low - density polyethylene (LDPE) to ethylene - butyl acrylate copolymer (EBA) is 4 - 8:1 - 2.5.

[0042] Low - density polyethylene (LDPE) is a semi - crystalline thermoplastic with good flexibility, processing performance, and electrical insulation performance. It is the main matrix resin of the cable insulation material, providing the basic mechanical properties and electrical insulation performance of the cable insulation material.

[0043] Ethylene - butyl acrylate copolymer (EBA) is the secondary matrix resin of the cable insulation material, used to improve the flexibility and processing performance of the cable insulation material.

[0044] The antioxidant is used to prevent the oxidation degradation of the cable insulation material during processing and use, extending the service life of the cable insulation material;

[0045] The crosslinking agent is dicumyl peroxide (DCP), which, as a free radical initiator, is used to initiate the crosslinking reaction of the cable insulation material. It can decompose to generate free radicals at 160 - 195 °C, forming a stable crosslinked network structure and improving the heat resistance and mechanical strength of the cable insulation material.

[0046] The toughening agent is ethylene - vinyl acetate copolymer (EVA), which is an elastomer copolymerized from ethylene and vinyl acetate. It can significantly improve the intermolecular toughness and impact resistance of the cable insulation material to achieve a good toughening effect while maintaining the overall performance balance of the cable insulation material.

[0047] S3: Add the mixed resin, mixture, antioxidant, crosslinking agent, and toughening agent into the twin - screw extruder respectively, and control the temperature in different zones to obtain a molten resin matrix.

[0048] The specific steps of S3 are as follows:

[0049] S3.1: First, add the mixed resin into the main feeding port of the twin - screw extruder simultaneously. Control the temperature of the main feeding port at 110 - 160 °C, and at the same time, the screw speed at 220 - 250 rpm. This is convenient for softening the low - density polyethylene (LDPE) in the mixed resin and melting the ethylene - butyl acrylate copolymer (EBA), promoting the blending effect of the low - density polyethylene (LDPE) and the ethylene - butyl acrylate copolymer (EBA).

[0050] S3.2: Add the toughening agent into the mixed resin through the first side feeding port. Control the temperature of the first side feeding port to be the same as that of the main feeding port, and the screw speed at 180 - 200 rpm. The elastomer characteristics of the toughening agent further enhance the intermolecular toughness of the overall cable insulation material. At the same time, reducing the screw speed can reduce the shear force of the screw, effectively avoiding the phenomenon of degradation due to excessive shear of the elastomer characteristics of the toughening agent.

[0051] S3.3: Inject the mixture and antioxidant into the twin - screw extruder together through the second side feeding port to obtain a molten resin matrix. Control the temperature of the second side feeding port at 150 - 185 °C, and at the same time, the screw speed at 250 rpm. Promote the interfacial bonding between the mixed resin and the modified nano - particles in the mixture, making the modified nano - particles evenly distributed in the molten resin matrix to improve insulation; at the same time, the antioxidant inhibits the oxidation of the mixed resin in the high - temperature section, extending the oxidation induction period to prevent the mixed resin from undergoing oxidative degradation during processing and use.

[0052] S4: Inject the crosslinking agent at the end of the twin - screw extruder, so that the crosslinking agent and the molten resin matrix complete the crosslinking reaction synchronously in the twin - screw extruder, forming a crosslinked matrix, and extruding to form a continuous strip - shaped cable insulation material, significantly improving the heat resistance, mechanical strength, and insulation performance of the cable insulation material.

[0053] The specific steps of S4 are as follows:

[0054] S4.1: Set a liquid injection pump at the end of the twin-screw extruder. Inject the crosslinking agent into the twin-screw extruder in liquid form through the liquid injection pump, so that the crosslinking agent is evenly dispersed in the molten resin matrix. Set the temperature at the end of the twin-screw extruder to 150 - 200 °C, the injection rate of the liquid injection pump to 3 - 7 mL / min, and the injection pressure to 0.5 - 1.0 MPa. Ensure that the crosslinking agent is evenly dispersed in the molten resin matrix. Heat the crosslinking agent to decompose and generate free radicals, which attack the carbon atoms of the mixed resin to form a crosslinked matrix, and extrude to form a continuous strip of cable insulation material. This is convenient for improving the crosslinking degree. At the same time, the screw speed is 200 - 300 rpm. If the speed is too high, it will shorten the residence time of the molten resin matrix and reduce the crosslinking degree.

[0055] Among them, the main feeding port is the first temperature control area, the first side feeding port is the second temperature control area, the second side feeding port is the third temperature control area, and the end of the twin-screw extruder is the fourth temperature control area, which is convenient for zoning temperature control of each temperature control area.

[0056] The end of the twin-screw extruder is located in front of the die head.

[0057] S4.2: Detect the torque change of the crosslinked matrix through an on-line rheometer to indirectly reflect the crosslinking degree;

[0058] The on-line rheometer is a device used to measure the rheological properties of cable insulation materials in real time. In the fields of plastic processing and rubber manufacturing, the on-line rheometer can reflect the rheological properties such as viscoelasticity and fluidity of cable insulation materials by measuring the torque change of the crosslinked matrix during rotation.

[0059] S4.3: Preset that the crosslinking degree deviates from the set range. If it is detected that the crosslinking degree deviates from the set range, automatically adjust the injection rate of the crosslinking agent and the screw speed;

[0060] Preset that the crosslinking degree deviates from the set range, such as < 75%. When it is detected that the crosslinking degree is low, the system will automatically increase the injection rate of the crosslinking agent and appropriately increase the screw speed to promote mixing and crosslinking reactions, promote more molecular chain crosslinking, and thus increase the crosslinking degree.

[0061] S4.4: Extrude the crosslinked matrix through the die head of the twin-screw extruder to form a continuous strip of cable insulation material.

[0062] S5: Gradually cool the extruded strip of cable insulation material through a gradient cooling method to avoid problems such as large internal stress generated inside the cable insulation material caused by rapid cooling, which in turn leads to increased brittleness and easy cracking during bending.

[0063] The specific steps of S5 are as follows:

[0064] S5.1: Set the initial cooling temperature and temperature reduction range of the water cooling device; the initial cooling temperature is 60-75°C, and the temperature reduction range is 5-8°C every 10-15 minutes until it drops to 15-20°C.

[0065] S5.2: The cooling medium flow rate of the preset water cooling device is 0.5-1.5m 3 / h, the cooling medium flow rate decreases by 0.1-0.2m every 10-15 minutes 3 / h, which is convenient for maintaining cooling uniformity.

[0066] S5.3: Send the extruded strip cable insulation material into the water cooling device, so that it enters the cooling medium and completes the cooling, so as to gradually reduce the temperature of the cooling medium. This is convenient to ensure that the cable insulation material can release heat evenly and slowly during the cooling process, and reduce the generation of internal stress. Avoid the problem of increased brittleness and easy cracking due to excessive internal stress of the cable insulation material. At the same time, it can also improve the uniformity of crystallinity of the cable insulation material, and improve its mechanical properties and anti-bending properties.

[0067] The water cooling device in S5 generally refers to a liquid cooling device, and is not limited to a water cooling device, and may be, for example, a synthetic coolant cooling device. The synthetic coolant has excellent heat conductivity, and can quickly remove the heat generated by the insulating cable insulation material during the extrusion process, ensuring that the temperature of the insulating cable insulation material is controlled within a suitable range, and preventing performance degradation or damage due to overheating;

[0068] In the above-mentioned preparation method of a cable insulation material, an appropriate amount of toughening agent is added. The toughening agent, with its excellent elastomeric properties, can significantly improve the intermolecular toughness of the cable insulation material, making it more resistant to external force impact. At the same time, combined with the optimization of the preparation method process, a gradient cooling method is used to gradually cool the extruded strip cable insulation material to reduce the generation of internal stress. In addition, controlling the cooling rate can change the crystallinity of the cable insulation material, thereby affecting its anti-bending performance, and thus effectively avoiding the generation of large internal stress inside the cable insulation material, causing increased brittleness and easy cracking due to bending.

[0069] A specific application example is given below:

[0070] A method for preparing a cable insulation material comprises the following steps:

[0071] S1: premixing the modified nanoparticles with epoxidized soybean oil to form a mixture, the premixing equipment is an ultrasonic disperser, and the dispersion time is 15-45 minutes;

[0072] Among them, the mass ratio of the modified nanoparticles to epoxidized soybean oil is 1:2.5;

[0073] S2: Weigh 30 parts of the mixed resin, 15 parts of the mixture, 0.1 part of the antioxidant, 0.2 part of the crosslinking agent, and 1 part of the toughening agent;

[0074] Among them, the mixed resin is low-density polyethylene (LDPE) and ethylene-butyl acrylate copolymer (EBA), and the mass ratio of low-density polyethylene (LDPE) to ethylene-butyl acrylate copolymer (EBA) is 4:1.

[0075] Low-density polyethylene (LDPE) is a semi-crystalline thermoplastic with good flexibility, processing performance, and electrical insulation performance. It is the main matrix resin of cable insulation materials, providing the basic mechanical properties and electrical insulation performance of cable insulation materials.

[0076] Ethylene-butyl acrylate copolymer (EBA) is the secondary matrix resin of cable insulation materials, used to improve the flexibility and processing performance of cable insulation materials.

[0077] The antioxidant is used to prevent the cable insulation material from undergoing oxidative degradation during processing and use, and to extend the service life of the cable insulation material;

[0078] The crosslinking agent is dicumyl peroxide (DCP). As a free radical initiator, it is used to initiate the crosslinking reaction of the cable insulation material, which can decompose to generate free radicals at 160 °C to form a stable crosslinked network structure, improving the heat resistance and mechanical strength of the cable insulation material.

[0079] The toughening agent is ethylene-vinyl acetate copolymer (EVA), which is an elastomer copolymerized from ethylene and vinyl acetate. It can significantly improve the intermolecular toughness and impact resistance of the cable insulation material to achieve a good toughening effect while maintaining the overall performance balance of the cable insulation material.

[0080] S3: Add the mixed resin, the mixture, the antioxidant, the crosslinking agent, and the toughening agent into a twin-screw extruder respectively, and control the temperature in different zones to obtain a molten resin matrix.

[0081] The specific steps of S3 are as follows:

[0082] S3.1: First, add the mixed resin into the main feeding port of the twin-screw extruder simultaneously, control the temperature of the main feeding port to be 110 °C, and at the same time, the screw speed is 220 rpm, which is convenient for softening the low-density polyethylene (LDPE) in the mixed resin and melting the ethylene-butyl acrylate copolymer (EBA), promoting the blending effect of low-density polyethylene (LDPE) and ethylene-butyl acrylate copolymer (EBA).

[0083] S3.2: Add the toughening agent into the mixed resin through the first side feed port, control the temperature of the first side feed port to be the same as that of the main feed port, and the screw rotation speed is 180 rpm.

[0084] S3.3: Inject the mixture and the antioxidant into the twin-screw extruder through the second side feed port together to obtain a molten resin matrix. Control the temperature of the second side feed port to be 150 °C, and at the same time the screw rotation speed is 250 rpm, which promotes the interfacial bonding between the mixed resin and the modified nanoparticles in the mixture, makes the modified nanoparticles evenly distributed in the molten resin matrix, and improves the insulation; at the same time, the antioxidant inhibits the oxidation of the mixed resin in the high-temperature section, prolongs the oxidation induction period, and prevents the mixed resin from undergoing oxidative degradation during processing and use.

[0085] S4: Inject the crosslinking agent at the end of the twin-screw extruder, so that the crosslinking agent and the molten resin matrix complete the crosslinking reaction synchronously in the twin-screw extruder to form a crosslinked matrix, and extrude to form a continuous strip of cable insulation material. Significantly improve the heat resistance, mechanical strength and insulation performance of the cable insulation material.

[0086] The specific steps of S4 are as follows:

[0087] S4.1: Set a liquid injection pump at the end of the twin-screw extruder, and inject the crosslinking agent into the twin-screw extruder in liquid form through the liquid injection pump, so that the crosslinking agent is evenly dispersed in the molten resin matrix. Set the temperature at the end of the twin-screw extruder to be 150 °C, the injection rate of the liquid injection pump is 3 mL / min, and the injection pressure is 0.5 MPa. Ensure that the crosslinking agent is evenly dispersed in the molten resin matrix. Make the crosslinking agent decompose by heat to generate free radicals, attack the carbon atoms of the mixed resin, form a crosslinked matrix, and extrude to form a continuous strip of cable insulation material. Facilitate improving the crosslinking degree. At the same time, the screw rotation speed is 200 rpm. Too high a rotation speed will shorten the residence time of the molten resin matrix and reduce the crosslinking degree.

[0088] S4.2: Detect the torque change of the crosslinked matrix through an on-line rheometer to indirectly reflect the crosslinking degree;

[0089] S4.3: Preset that the crosslinking degree deviates from the set range. If it is detected that the crosslinking degree deviates from the set range, automatically adjust the injection rate of the crosslinking agent and the screw rotation speed;

[0090] Preset that the crosslinking degree deviates from the set range. For example, <75%. When it is detected that the crosslinking degree is low, the system will automatically increase the injection rate of the crosslinking agent and appropriately increase the screw rotation speed to promote mixing and crosslinking reactions, promote more molecular chain crosslinking, and thus improve the crosslinking degree.

[0091] S4.4: Extrude the crosslinked matrix through the die head of the twin-screw extruder to form a continuous strip of cable insulation material.

[0092] S5: Gradually cool the extruded strip-shaped cable insulating material by means of gradient cooling to avoid the problem that rapid cooling leads to large internal stresses generated inside the cable insulating material, which in turn causes an increase in brittleness and easy cracking during bending.

[0093] The specific steps of S5 are as follows:

[0094] S5.1: Set the initial cooling temperature and the temperature reduction range of the water cooling device; the initial cooling temperature is 60 °C, and the temperature reduction range is to reduce by 5 °C every 10 minutes until it reaches 15 °C.

[0095] S5.2: Preset the flow rate of the cooling medium of the water cooling device to be 0.5 m 3 / h, and the flow rate of the cooling medium is reduced by 0.1 m 3 / h every 10 minutes to facilitate maintaining the uniformity of cooling.

[0096] S5.3: Feed the extruded strip-shaped cable insulating material into the water cooling device to make it enter the cooling medium, so as to gradually reduce the temperature of the cooling medium.

[0097] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

Claims

1. A method for preparing a cable insulating material, characterized in that, The method includes the following steps: S1: Premix the modified nanoparticles and epoxidized soybean oil to form a mixture; S2: Weigh 30 - 50 parts of mixed resin, 15 - 20 parts of the mixture, 0.1 - 0.4 parts of antioxidant, 0.2 - 0.6 parts of crosslinking agent, and 1 - 2 parts of toughening agent; S3: Add the mixed resin, the mixture, the antioxidant, the crosslinking agent, and the toughening agent into a twin - screw extruder respectively, and control the temperature in different zones to obtain a molten resin matrix; S4: Inject the crosslinking agent at the end of the twin - screw extruder, so that the crosslinking agent and the molten resin matrix complete the crosslinking reaction synchronously in the twin - screw extruder to form a crosslinked matrix, and extrude to form a continuous strip - shaped cable insulating material; S5: Gradually cool the extruded strip - shaped cable insulating material by a gradient cooling method.

2. The preparation method of a cable insulating material according to claim 1, wherein, The mass ratio of the modified nanoparticles to epoxidized soybean oil is 1 - 2:2.5 - 5. Epoxidized soybean oil is used as a dispersion medium to prevent the agglomeration of the modified nanoparticles. The modified nanoparticles are modified nano - boron nitride particles.

3. A method for preparing a cable insulating material according to claim 1, characterized in that, The mixed resin is low - density polyethylene and ethylene - butyl acrylate copolymer, and the mass ratio of low - density polyethylene to ethylene - butyl acrylate copolymer is 4 - 8:1 - 2.

5.

4. The preparation method of a cable insulating material according to claim 1, characterized in that The specific steps of S3 are as follows: S3.1: First, add the mixed resin into the main feeding port of the twin - screw extruder simultaneously, control the temperature of the main feeding port at 110 - 160 °C, and the screw speed at 220 - 250 rpm; S3.2: Add the toughening agent into the mixed resin through the first side feeding port, control the temperature of the first side feeding port to be the same as that of the main feeding port, and the screw speed at 180 - 200 rpm; S3.3: Inject the mixture and the antioxidant into the twin - screw extruder together through the second side feeding port to obtain a molten resin matrix.

5. The preparation method of a cable insulating material according to claim 4, wherein The screw speed at the main feeding port is 220 rpm, the screw speed at the first side feeding port is 180 rpm, and the screw speed at the second side feeding port is 250 rpm.

6. The preparation method of a cable insulating material according to claim 1, characterized in that The specific steps of S4 are as follows: S4.1: Set a liquid injection pump at the end of the twin - screw extruder, and inject the crosslinking agent into the twin - screw extruder in liquid form through the liquid injection pump to make the crosslinking agent evenly dispersed in the molten resin matrix; S4.2: Detect the torque change of the crosslinked matrix through an on - line rheometer to indirectly reflect the crosslinking degree; S4.3: Preset that the crosslinking degree deviates from the set range. If it is detected that the crosslinking degree deviates from the set range, automatically adjust the injection rate of the crosslinking agent and the screw speed; S4.4: Extrude the crosslinked matrix through the die head of the twin - screw extruder to form a continuous strip - shaped cable insulating material.

7. The preparation method of a cable insulating material according to claim 1, characterized in that, The specific steps of S5 are as follows: S5.1: Set the initial cooling temperature and the temperature reduction range of the water cooling device; the initial cooling temperature is 60 - 75 °C, and the temperature reduction range is to reduce 5 - 8 °C every 10 - 15 minutes until it drops to 15 - 20 °C; S5.2: Set the flow rate of the cooling medium of the preset water cooling device to 0.5 - 1.5 m 3 / h, and the flow rate of the cooling medium decreases by 0.1 - 0.2 m 3 / h every 10 - 15 minutes; S5.3: Feed the extruded strip - shaped cable insulating material into the water cooling device to make it enter the cooling medium to complete the cooling.

8. The preparation method of a cable insulating material according to claim 4, characterized in that, The main feeding port is the first temperature control area, the first side feeding port is the second temperature control area, and the second side feeding port is the third temperature control area.

9. The preparation method of a cable insulating material according to claim 8, wherein The temperature of the first temperature control region is 110 - 160 °C, the temperature of the second temperature control region is the same as that of the first temperature control region, and the third temperature control region is 150 - 185 °C.

10. A method for preparing a cable insulating material according to claim 6, characterized in that, The injection rate of the liquid injection pump is 3 - 7 mL / min, and the injection pressure is 0.5 - 1.0 MPa.

Images