WO2024016580A1

WO2024016580A1 - Shielding material based on carbon nanofiber modification, and preparation method therefor and use thereof

Info

Publication number: WO2024016580A1
Application number: PCT/CN2022/139584
Authority: WO
Inventors: 侯帅; 傅明利; 黎小林; 贾磊; 朱闻博; 展云鹏; 惠宝军; 冯宾; 张逸凡
Original assignee: 南方电网科学研究院有限责任公司
Priority date: 2022-07-22
Filing date: 2022-12-16
Publication date: 2024-01-25
Also published as: CN115044130A

Abstract

The present application relates to a shielding material based on carbon nanofiber modification, which shielding material is prepared from the following components, in parts by mass: 55-65 parts of a base resin, 20-30 parts of conductive carbon black, 1-10 parts of carbon nanofibers, 0.5-2 parts of a dispersant, 3-6 parts of a functional auxiliary agent and 0.9-2 parts of a cross-linking agent.

Description

Shielding materials modified by carbon nanofibers and preparation methods and applications thereof

This application requires the priority of the Chinese patent application submitted to the China Patent Office on July 22, 2022, with the application number 2022108683557 and the invention name "Shielding material based on carbon nanofiber modification and its preparation method and application", and its entire content incorporated herein by reference.

Technical field

The present invention relates to the technical field of high-voltage cable materials, and in particular to a shielding material modified based on carbon nanofibers and its preparation method and application.

Background technique

In power cables, the semi-conductive shielding layer plays a role in uniformizing the electric field on the surface of the conductor and eliminating partial discharge. It effectively avoids partial discharge between the conductor and the insulator, the insulator and the metal sheath, and greatly increases the service life of the cable. However, in traditional semi-conductive shielding materials for high-voltage cables, the balance between electrical conductivity and mechanical properties needs to be further improved.

Contents of the invention

Based on this, it is necessary to provide a carbon nanofiber-modified shielding material that can take into account both good electrical conductivity and good mechanical properties, as well as its preparation method and application.

In order to solve the above technical problems, the technical solution of an embodiment of the present invention is:

A shielding material modified based on carbon nanofibers, made of the following components by mass: 55 to 65 parts of basic resin, 20 to 30 parts of conductive carbon black, 1 to 10 parts of carbon nanofibers, 0.5 to 2 parts of dispersant, 3 to 6 parts of functional additives and 0.9 to 2 parts of cross-linking agent.

In some embodiments, the functional additive is made of components including the following mass parts: 1 to 2 parts of coupling agent, 1 to 3 parts of lubricant, and 0.6 to 1 part of antioxidant.

In some embodiments, the coupling agent is a silane coupling agent.

In some embodiments, the lubricant is one or more of zinc stearate and pentaerythritol.

In some embodiments, the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

In some embodiments, the base resin is at least one of ethylene-vinyl acetate copolymer, ethylene-butyl acrylate copolymer, and ethylene-ethyl acrylate copolymer.

In some embodiments, the DBP absorption value of the conductive carbon black is 120ml/100g～200ml/100g.

In some embodiments, the conductive carbon black has an ash content of ≤0.2%.

In some embodiments, the carbon nanofibers have a purity of ≥95%.

In some embodiments, the diameter of the carbon nanofibers is 50 nm to 200 nm.

In some embodiments, the length of the carbon nanofibers is 1 μm to 15 μm.

In some embodiments, the dispersant is at least one of ethylene bisstearamide and oleic acid amide.

In some embodiments, the cross-linking agent is at least one of di-tert-butyl cumene peroxide and dicumyl peroxide.

A method for preparing the above-mentioned carbon nanofiber-modified shielding material, which is characterized by including the following steps:

Mix the conductive carbon black, the carbon nanofibers and the dispersant to obtain a first mixture;

Mix the first mixture, the functional additive and the base resin to obtain a second mixture;

Extruding and pelletizing the second mixture to obtain pellets;

Mix the pellets and the cross-linking agent to obtain a pre-finished product;

The pre-finished product is subjected to heat treatment.

In some embodiments, mixing the first mixture, the functional additive and the base resin is to first mix the first mixture with the functional additive, then add the base resin, and at 40 ℃ ~ 50 ℃ to continue mixing.

In some embodiments, the stirring speed when mixing the first mixture and the functional additive is 150 rpm to 200 rpm.

In some embodiments, the second mixture is extruded at an extrusion temperature of 150°C to 180°C.

In some embodiments, the temperature of the heat treatment is 50°C to 70°C.

A semi-conductive shielding sleeve for high-voltage cables is made of raw materials including the above-mentioned shielding material modified based on carbon nanofibers.

Detailed ways

In order to make the above objects, features and advantages of the present application more obvious and easy to understand, the specific implementation modes of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described here. Those skilled in the art can make similar improvements without violating the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing specific embodiments only and is not intended to limit the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

One embodiment of the present invention provides a shielding material modified based on carbon nanofibers. The shielding material modified based on carbon nanofibers is made of components including the following parts by mass: 55 to 65 parts of basic resin, 20 to 30 parts of conductive carbon black, 1 to 10 parts of carbon nanofibers, and dispersant 0.5 to 2 parts, 3 to 6 parts of functional additives and 0.9 to 2 parts of cross-linking agent. Among them, carbon nanofibers and conductive carbon black work together to form a good conductive network structure, which improves the conductive properties of high-voltage cable semi-conductive shielding materials. In addition, the introduction of carbon nanofibers hinders the re-aggregation process of conductive carbon black, which is beneficial to the dispersion of conductive carbon black and stabilizes the mechanical properties. At the same time, among the above-mentioned shielding materials, the high-voltage cable semi-conductive shielding material can have good mechanical properties through the ratio of raw materials, so that the high-voltage cable semi-conductive shielding material has both good electrical conductivity and good mechanical properties.

Furthermore, in this embodiment, through the combination of carbon nanofibers and conductive carbon black, the adverse effects on mechanical properties and processing properties of high-voltage cable semi-conductive shielding materials that require an increase in the amount of conductive carbon black to obtain predetermined conductivity are overcome. At the same time, it also overcomes the problem that the conductive network of conductive carbon black in the base resin is unstable and the conductivity is greatly affected by temperature changes.

In a specific example, the shielding material modified based on carbon nanofibers is made of components including the following parts by mass: 60 to 64 parts of base resin, 25 to 29 parts of conductive carbon black, and 1 part of carbon nanofibers. ~5 parts, 1~1.5 parts of dispersant, 3~5 parts of functional additives and 1~2 parts of cross-linking agent.

Further, the mass ratio of conductive carbon black to carbon nanofibers is 29:1 to 5:1. Optionally, the mass ratio of conductive carbon black to carbon nanofibers is 29:1 to 25:5. Preferably, the mass ratio of conductive carbon black to carbon nanofibers is 27:3.

As an optional example of the mass parts of the base resin, the mass parts of the base resin can be but are not limited to 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts , 64 servings or 65 servings. It is understandable that the mass fraction of the base resin can also be appropriately selected in the range of 55 to 65 parts.

As an optional example of the mass fraction of conductive carbon black, the mass fraction of conductive carbon black can be but is not limited to 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28, 29 or 30 servings. It is understandable that the mass fraction of conductive carbon black can also be appropriately selected within the range of 20 to 30 parts.

As an optional example of the mass fraction of carbon nanofibers, the mass fraction of carbon nanofibers can be, but is not limited to, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, Serves 9 or 10. It is understandable that the mass fraction of carbon nanofibers can also be appropriately selected in the range of 1 to 10 parts.

As an optional example of the mass parts of the dispersant, the mass parts of the dispersant may be, but are not limited to, 0.5 parts, 0.8 parts, 1 part, 1.1 parts, 1.2 parts, 1.4 parts, 1.5 parts, 1.7 parts, 1.9 parts Or 2 servings. It is understandable that the mass fraction of the dispersant can also be appropriately selected in the range of 0.5 to 2 parts.

As an optional example of the mass parts of the functional assistant, the mass parts of the functional assistant can be but are not limited to 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4 parts, 4.2 parts, 4.5 parts, 4.8 parts, 5 servings, 5.2 servings, 5.5 servings, 5.8 servings or 6 servings. It is understandable that the mass fraction of functional additives can also be appropriately selected within the range of 3 to 6 parts.

As an optional example of the mass fraction of the cross-linking agent, the mass fraction of the cross-linking agent may be, but is not limited to, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts or 2 parts. It is understandable that the mass fraction of the cross-linking agent can also be appropriately selected in the range of 0.9 to 2 parts.

Another embodiment of the present invention provides a shielding material modified based on carbon nanofibers. The shielding material modified based on carbon nanofibers is made of the following components by mass: 55 to 65 parts of basic resin, 20 to 30 parts of conductive carbon black, 1 to 10 parts of carbon nanofibers, and 0.5 parts of dispersant 0.9 to 2 parts of functional additives, 3 to 6 parts of functional additives and 0.9 to 2 parts of cross-linking agents. In this example, the mass parts are 55 to 65 parts of base resin, 20 to 30 parts of conductive carbon black, 1 to 10 parts of carbon nanofibers, 0.5 to 2 parts of dispersant, 3 The combination of 0.9 to 6 parts of functional additives and 0.9 to 2 parts of cross-linking agent can make the shielding material have both good conductive properties and good mechanical properties.

In a specific example, as a selection of functional additives, the functional additive is made of components including the following mass parts: 1 to 2 parts of coupling agent, 1 to 3 parts of lubricant, and 0.6 parts of antioxidant Serving ~ 1 serving. Optionally, the coupling agent is a silane coupling agent. The lubricant is one or more of zinc stearate and pentaerythritol. The antioxidant is at least one of antioxidant 1010 and antioxidant 168. Further optionally, silane coupling agent KH550. The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 at a mass ratio of 1: (0.8 to 1.5). Furthermore, the mass ratio of antioxidant 1010 and antioxidant 168 may be but is not limited to 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5. Optionally, the functional additive is mixed with a coupling agent, a lubricant and an antioxidant.

It can be understood that in the functional auxiliary agent, the mass fraction of the coupling agent may be, but is not limited to, 1 part, 1.2 parts, 1.5 parts, 1.8 parts or 2 parts, etc. The mass parts of the lubricant may be, but are not limited to, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts or 3 parts, etc. The mass parts of the antioxidant may be, but are not limited to, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts or 1 part, etc. It can also be understood that the mass fraction of the coupling agent can also be made in the range of 1 to 2 parts, and the mass fraction of the lubricant can also be made in the range of 1 to 3 parts. , the mass fraction of the antioxidant can also be appropriately selected within the range of 0.6 to 1 part.

As an optional example of the base resin, the base resin is cross-linked polyethylene (XLPE). Optionally, the base resin is at least one of ethylene-vinyl acetate copolymer (EVA), ethylene-butyl acrylate copolymer (EBA), and ethylene-ethyl acrylate copolymer (EEA). When preparing semi-conductive shielding materials for high-voltage cables, the shielding materials for cross-linked polyethylene insulated cables can use ethylene-vinyl acetate copolymer (EVA), ethylene-butyl acrylate copolymer (EBA) and ethylene-ethyl acrylate copolymer. (EEA) as the matrix. However, when used as shielding material for cables with voltage levels of 110kV and above, ethylene-vinyl acetate copolymer (EVA) will release a small amount of acidic substances under high voltage to corrode copper conductors, reducing the service life of the cable. Preferably, the base resin is ethylene-butyl acrylate copolymer (EBA).

As an optional example of conductive carbon black, the DBP (dibutyl phthalate) absorption value of conductive carbon black is 120ml/100g～200ml/100g. For example, the DBP absorption value of conductive carbon black is 120ml/100g, 130ml/100g, 150ml/100g, 180ml/100g or 200ml/100g, etc. Further, the ash content of the conductive carbon black is ≤0.2%. Furthermore, the ash content of the conductive carbon black is <0.2%, and still further, the ash content of the conductive carbon black is <0.1%.

As an optional example of carbon nanofibers, the purity of carbon nanofibers is ≥95%. For example, the purity of carbon nanofibers is ≥97%. Further, the diameter of the carbon nanofibers is 50 nm to 200 nm. Alternatively, the diameter of the carbon nanofibers may be, but is not limited to, 50 nm, 70 nm, 80 nm, 100 nm, 150 nm, 180 nm or 200 nm, etc. Furthermore, the length of the carbon nanofibers is 1 μm to 15 μm. Optionally, the length of the carbon nanofibers is 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm or 15 μm, etc.

As an optional example of the dispersant, the dispersant is at least one of ethylene bisstearamide (EBS) and oleic acid amide.

As an optional example of the cross-linking agent, the cross-linking agent is at least one of bis-tert-butylperoxycumylbenzene (BIPB) and dicumyl peroxide (DCP).

Another embodiment of the present invention provides a method for preparing the above-mentioned shielding material modified based on carbon nanofibers. The preparation method of the carbon nanofiber-modified shielding material includes the following steps: mixing conductive carbon black, carbon nanofibers and a dispersant to obtain a first mixture; mixing the first mixture, functional additives and basic resin to obtain a third mixture. two mixtures; extruding and pelletizing the second mixture to obtain pellets; mixing the pellets and a cross-linking agent to obtain a pre-finished product; and heat-treating the pre-finished product. In the preparation method of this embodiment, through the selection and proportioning of raw materials, the constraints of the conductive carbon black on the processing technology are effectively reduced, and the preparation difficulty is reduced. The preparation method is simple and easy to implement, and is suitable for promotion.

In a specific example, the conductive carbon black, carbon nanofibers and dispersant are mixed by stirring and mixing for 8 to 20 minutes. Alternatively, the mixing time may be, but is not limited to, 8 min, 10 min, 15 min, 18 min or 20 min, etc. It is understandable that stirring and mixing are performed in a mixer, and by setting the working parameters of the mixer, the speed, time, etc. of stirring and mixing can be conveniently controlled.

In a specific example, mixing the first mixture, the functional additive and the base resin is to first mix the first mixture and the functional additive, then add the base resin, and continue mixing at 40°C to 50°C. Alternatively, the first mixture is mixed with the functional additive, and then the mixing temperature after adding the base resin may be, but is not limited to, 40°C, 42°C, 45°C, 48°C or 50°C, etc. Further, the stirring speed when mixing the first mixture and the functional additive is 150 rpm to 200 rpm, and the mixing time is 8 min to 20 min. Optionally, the stirring speed when mixing the first mixture and the functional additive is 150rpm, 160rpm, 170rpm, 180rpm, 190rpm or 200rpm, etc. The mixing time is 8min, 10min, 15min or 20min, etc. It is understandable that stirring and mixing are performed in a mixer, and by setting the working parameters of the mixer, the speed, time, etc. of stirring and mixing can be conveniently controlled.

In a specific example, the extrusion temperature for extruding the second mixture is 150°C to 180°C. For example, the extrusion temperature is 150°C, 160°C, 170°C or 180°C, etc. It can be understood that extrusion is performed in an extruder, and during extrusion, the main engine speed of the extruder is controlled to be 80 rpm to 150 rpm. For example, control the main engine speed of the extruder to 80rpm, 90rpm, 100rpm, 110rpm, 120rpm, 130rpm or 140rpm, etc. Optionally, extrusion is performed in a twin-screw extruder.

Further, before mixing the pellets and the cross-linking agent, the following step is also included: keeping the pellets warm at 50°C to 70°C. Optionally, the insulation temperature is 50°C, 55°C, 60°C, 65°C, or 70°C, etc. Furthermore, the holding time is 3h to 6h. Optionally, the holding time is 3h, 4h, 5h or 6h, etc.

Furthermore, before mixing the pellets and the cross-linking agent, the following step is also included: grinding the cross-linking agent. The grinding time is 8min~20min. Specifically, the grinding time is 8 min, 10 min, 15 min or 20 min, etc. It will be appreciated that grinding can be performed in a grinder.

In a specific example, the pelletizing is done underwater. It is understandable that after underwater pelletizing, the pelletized materials are dried to remove moisture and then kept warm.

In a specific example, the temperature of the heat treatment is 50°C to 70°C. Optionally, the temperature of the heat treatment is 50°C, 55°C, 60°C, 65°C, or 70°C, etc. Further, the heat treatment time is 5h to 10h. Optionally, the heating treatment time is 5h, 6h, 7h, 8h, 9h or 10h, etc. Through heat treatment, the cross-linking agent can be fully absorbed by the pellets to improve the performance of the carbon nanofiber-modified shielding material.

It can be understood that in preparing the shielding material, before mixing the conductive carbon black, carbon nanofibers and dispersing agent, the following steps are also included: mixing the base resin, conductive carbon black, carbon nanofibers, dispersing agent, functional additives and cross-linking agent. The ingredients are dried to remove moisture from each raw material.

Another embodiment of the present invention provides a semi-conductive shielding sleeve for high-voltage cables. The shielding sleeve is made of raw materials including the above-mentioned shielding material modified based on carbon nanofibers. Optionally, the high-voltage cable semi-conductive shielding sleeve is extruded from a raw material including the above-mentioned carbon nanofiber-modified shielding material.

In a specific example, the raw materials for preparing the high-voltage cable semi-conductive shielding sleeve also include insulating materials. The high-voltage cable semi-conductive shielding sleeve is made by extrusion molding of raw materials including the above-mentioned carbon nanofiber-modified shielding material and insulating material.

The following are specific examples.

Example 1

In terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this embodiment are: 63.5 parts of basic resin, 29 parts of conductive carbon black, 1 part of carbon nanofibers, 1 part of dispersant, and 4.5 parts of functional additives parts and 1 part of cross-linking agent. Among them, the base resin is ethylene-butyl acrylate copolymer. The DBP absorption value of conductive carbon black is 150ml/100g, and the ash content of conductive carbon black is <0.2%. The purity of carbon nanofibers is >95%, the diameter of carbon nanofibers is 80-100nm, and the length of carbon nanofibers is 6-8 μm. The dispersant is ethylene bisstearamide. The cross-linking agent is bis-tert-butylperoxycumylbenzene (BIPB).

In terms of parts by mass, functional additives are mixed with the following raw materials: 2 parts of coupling agent, 2 parts of lubricant and 0.5 part of antioxidant. Among them, the coupling agent is silane coupling agent KH550. The lubricant is zinc stearate. The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 at a mass ratio of 1:1.

In this embodiment, the preparation method of the carbon nanofiber-modified shielding material includes the following steps:

S101: Dry the base resin, conductive carbon black, carbon nanofibers, dispersants, functional additives and cross-linking agents to remove moisture.

S102: Mix conductive carbon black, carbon nanofibers and dispersant for 10 minutes to obtain the first mixture.

S103: Mix the first mixture and the functional additive at a stirring speed of 160 rpm for 10 minutes, then add the base resin, and continue to mix evenly at 45°C to obtain the second mixture.

S104: The second mixture is melt-extruded in a twin-screw extruder, the extrusion temperature is 160°C, and the main engine speed is 100 rpm. After extrusion, it is pelletized under water to obtain pellets.

S105: Dry the pellets to remove moisture, and then keep them at 60°C for 4 hours.

S106: Grind the cross-linking agent in a grinder for 10 minutes.

S107: Mix the pelletized material after heat preservation and the cross-linking agent after grinding to obtain a pre-finished product.

S108: Heat the pre-finished product at 60°C for 8 hours.

After heating, the carbon nanofiber-modified shielding material in this embodiment is obtained.

Example 2

Compared with Example 1, the difference in this example is that in terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this example are: 63.5 parts of basic resin and 28 parts of conductive carbon black. , 2 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 1 part of cross-linking agent.

Example 3

Compared with Example 1, the difference in this example is that in terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this example are: 63.5 parts of basic resin and 27 parts of conductive carbon black. , 3 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 1 part of cross-linking agent.

Example 4

Compared with Example 1, the difference in this example is that in terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this example are: 63.5 parts of basic resin and 26 parts of conductive carbon black. , 4 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 1 part of cross-linking agent.

Example 5

Compared with Example 1, the difference in this example is that the base resin is an ethylene-vinyl acetate copolymer.

Example 6

Compared with Example 1, the difference in this example is that the base resin is an ethylene-ethyl acrylate copolymer.

Example 7

Compared with Example 1, the difference in this example is that in terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this example are: 55 parts of basic resin and 20 parts of conductive carbon black. , 1 part carbon nanofiber, 1 part dispersant, 4.5 parts functional additives and 1 part cross-linking agent.

Example 8

Compared with Example 1, the difference in this example is that in terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this example are: 65 parts of basic resin and 30 parts of conductive carbon black. , 5 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 2 parts of cross-linking agent.

Comparative example 1

Compared with Example 1, the difference of this comparative example is that in terms of parts by mass, the raw materials for preparing the shielding material in this example are: 63.5 parts of basic resin, 30 parts of conductive carbon black, 0 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 1 part of cross-linking agent.

Comparative example 2

Compared with Example 1, the difference of this comparative example is that in terms of parts by mass, the raw materials for preparing the shielding material in this example are: 61.5 parts of basic resin, 32 parts of conductive carbon black, 0 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 1 part of cross-linking agent.

Comparative example 3

Compared with Example 1, the difference of this comparative example is that in terms of parts by mass, the raw materials for preparing the shielding material in this example are: 58.5 parts of basic resin, 35 parts of conductive carbon black, 0 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 1 part of cross-linking agent.

Comparative example 4

In terms of parts by mass, the raw materials for preparing the shielding material in this embodiment are: 63.5 parts of base resin, 29 parts of conductive carbon black, 1 part of multi-walled carbon nanotubes, 1 part of dispersant, 4.5 parts of functional additives and cross-linking agent 1 serving. Among them, the diameter of multi-walled carbon nanotubes is 30~60nm, the purity is >95%, and the length is 0.5~3um.

Comparative example 5

Compared with Example 1, the difference of this comparative example is that in terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this example are: 78.5 parts of basic resin and 15 parts of conductive carbon black. , 0.5 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 0.5 parts of cross-linking agent.

Comparative example 6

Compared with Example 1, the difference of this comparative example is that in terms of parts by mass, the raw materials for preparing the shielding material modified by carbon nanofibers in this example are: 51.5 parts of basic resin and 35 parts of conductive carbon black. , 5 parts of carbon nanofibers, 1 part of dispersant, 4.5 parts of functional additives and 3 parts of cross-linking agent.

test case

The shielding materials obtained in the examples and comparative examples were pressed into test plates with a thickness of 1 mm. Then the test plates were tested for tensile strength, elongation at break, volume resistivity at room temperature and volume resistivity at 90°C. The test results are shown in Table 1.

Table 1

As can be seen from Table 1, both the examples and the comparative examples show good mechanical properties and electrical properties. In Comparative Example 1, Example 1, Example 2, Example 3 and Example 4, the amount of carbon nanofibers gradually increased. At this time, the resistivity at 23°C and the resistivity at 90°C gradually decreased, and the mechanical properties decreased slightly, both of which were consistent with the performance. Indicator requirements. The introduction of carbon nanofibers can build a more effective conductive network in the base resin, increasing its electrical properties. The carbon nanofibers hinder the re-aggregation process of conductive carbon black during mixing, which is beneficial to the dispersion of conductive carbon black. , making the mechanical properties stable. And with the reduction of conductive carbon black content, the mechanical properties of the shielding material will be optimized.

In addition, comparing Example 3 with Comparative Example 3, in Example 3, the conductive carbon black is 27 parts, the carbon nanofiber is 3 parts, the tensile strength of the shielding material is 15.5MPa, the elongation at break is 252.3%, and the resistivity at 23°C and 90°C resistivity are 10.6Ω·cm and 182.3Ω·cm respectively. In Comparative Example 3, the conductive carbon black is 35 parts, the carbon nanofibers are 0 parts, the tensile strength of the shielding material is 15.1MPa, the elongation at break is 245.1%, and the resistivity at 23°C and the resistivity at 90°C are 14.2Ω·cm respectively. and 248.9Ω·cm. It can be seen that the introduction of carbon nanofibers can effectively reduce the content of conductive carbon black and achieve excellent electrical and mechanical properties. The combination of conductive carbon black and carbon nanofibers is added as a conductive filler to the base resin. Since the carbon nanofibers and conductive carbon black synergistically form a good conductive network structure in the base resin, the conductivity of the high-voltage cable semi-conductive shielding material can be improved. , thus reducing the conductive carbon black content in the high-voltage cable semi-conductive shielding material, thereby achieving the same conductive performance as when the carbon black content is high. Moreover, after the introduction of carbon nanofibers, the conductive network constructed by the conductive filler in the base resin is stable and is less affected by temperature changes.

Furthermore, as can be seen from Table 1, in the embodiment, the composition of the conductive network is controlled by adjusting the ratio of conductive carbon black and carbon nanofibers, thereby obtaining a shielding material with excellent comprehensive performance. Among them, when the ratio of conductive carbon black and carbon nanofibers is 29:1 to 25:5, better overall performance of the shielding material can be obtained. When the ratio of conductive carbon black and carbon nanofibers is 27:3 , the shielding material has the best overall performance. Furthermore, compared with Comparative Example 4. Compared with carbon nanotubes, carbon nanofibers have a smaller aspect ratio and are not easy to bend. They can form a more stable conductive network, and their electrical properties are less affected by temperature.

The technical features of the above-described embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-mentioned embodiments only express several implementation modes of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims, and the description can be used to interpret the content of the claims.

Claims

A shielding material modified based on carbon nanofibers, characterized in that it is made of components including the following parts by mass: 55 to 65 parts of basic resin, 20 to 30 parts of conductive carbon black, and 1 part of carbon nanofibers. ~10 parts, dispersant 0.5~2 parts, functional additives 3~6 parts and cross-linking agent 0.9~2 parts.
The shielding material based on carbon nanofiber modification according to claim 1, characterized in that the functional additive is made of components including the following mass parts: 1 to 2 parts of coupling agent, 1 part of lubricant parts to 3 parts and antioxidants 0.6 to 1 part.
The shielding material modified based on carbon nanofibers according to any one of claims 1 to 2, characterized in that the coupling agent is a silane coupling agent.
The shielding material modified based on carbon nanofibers according to any one of claims 1 to 3, characterized in that the lubricant is one or more of zinc stearate and pentaerythritol.
The shielding material based on carbon nanofiber modification according to any one of claims 1 to 4, characterized in that the antioxidant is at least one of antioxidant 1010 and antioxidant 168.
The shielding material based on carbon nanofiber modification according to any one of claims 1 to 5, characterized in that the base resin is ethylene-vinyl acetate copolymer, ethylene-butyl acrylate copolymer and ethylene- At least one of the ethyl acrylate copolymers.
The shielding material based on carbon nanofiber modification according to any one of claims 1 to 6, characterized in that the DBP absorption value of the conductive carbon black is 120ml/100g～200ml/100g.
The shielding material modified based on carbon nanofibers according to any one of claims 1 to 7, characterized in that the ash content of the conductive carbon black is ≤0.2%.
The shielding material modified based on carbon nanofibers according to any one of claims 1 to 8, characterized in that the purity of the carbon nanofibers is ≥95%.
The shielding material modified based on carbon nanofibers according to any one of claims 1 to 9, wherein the diameter of the carbon nanofibers is 50 nm to 200 nm.
The shielding material modified based on carbon nanofibers according to any one of claims 1 to 10, wherein the length of the carbon nanofibers is 1 μm to 15 μm.
The carbon nanofiber-modified shielding material according to any one of claims 1 to 11, wherein the dispersant is at least one of ethylene bisstearamide and oleic acid amide.
The shielding material based on carbon nanofiber modification according to any one of claims 1 to 12, characterized in that the cross-linking agent is di-tert-butyl cumene peroxide and dicumyl peroxide. at least one of them.
A method for preparing a carbon nanofiber-modified shielding material according to any one of claims 1 to 13, characterized in that it includes the following steps:

Mix the conductive carbon black, the carbon nanofibers and the dispersant to obtain a first mixture;

Mix the first mixture, the functional additive and the base resin to obtain a second mixture;

Extruding and pelletizing the second mixture to obtain pellets;

Mix the pellets and the cross-linking agent to obtain a pre-finished product;

The pre-finished product is subjected to heat treatment.
The method for preparing a carbon nanofiber-modified shielding material according to claim 14, wherein the first mixture, the functional additive and the base resin are mixed by first mixing the first mixture. Mix with the functional additives, then add the base resin, and continue mixing at 40°C to 50°C.
The method for preparing a carbon nanofiber-modified shielding material according to claim 15, wherein the stirring speed when mixing the first mixture and the functional additive is 150 rpm to 200 rpm.
The method for preparing a carbon nanofiber-modified shielding material according to any one of claims 14 to 16, wherein the second mixture is extruded at an extrusion temperature of 150°C to 180°C.
The method for preparing a carbon nanofiber-modified shielding material according to any one of claims 14 to 17, wherein the temperature of the heat treatment is 50°C to 70°C.
A semi-conductive shielding sleeve for high-voltage cables, characterized in that it is made of raw materials including the carbon nanofiber-modified shielding material according to any one of claims 1 to 13.