Semi-conductive shielding material, preparation method and application thereof, and high-voltage cable

Abstract

The invention provides a semiconductive shielding material, a preparation method and application thereof and a high-voltage cable, and belongs to the technical field of high-voltage cable materials. The semiconductive shielding material is prepared from the following components in parts by weight: 60 to 70 parts of matrix resin, 20 to 30 parts of carbon black, 5 to 10 parts of Diels-Alder cross-linking agent, 1 to 3 parts of antioxidant and 2 to 5 parts of dispersing agent, the Diels-Alder cross-linking agent is prepared from a furan compound and a maleic acid derivative. A Diels-Alder type dynamic covalent cross-linking structure is introduced by adopting a Diels-Alder cross-linking agent consisting of a furan compound and a maleic acid derivative in certain parts by mass to construct a reversible cross-linking network, so that the scorching phenomenon can be remarkably inhibited, the conductivity and the mechanical property are improved, the material processing window is improved, the industrial applicability is excellent, and the application prospect is wide. And the operation stability of the high-voltage cable can be improved when the cable is used.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage cable materials, and in particular to a semi-conductive shielding material, a preparation method thereof, an application thereof, and a high-voltage cable. Background Art

[0002] High-voltage cables typically consist of a conductor, an insulation layer, an inner semi-conductive shield, an insulation layer, a semi-conductive shield, and a sheath. The semi-conductive shield, located between the insulation layer and the conductor, distributes the electric field uniformly, eliminates defects in the cable insulation and at the interface between the conductor and the metal shield, and suppresses space charge injection. It is a critical structure for ensuring the long-term and stable operation of high-voltage cables.

[0003] To further extend the service life of high-voltage cables, peroxide-based crosslinking agents are often used to induce free radical crosslinking during processing to improve the thermal stability and mechanical strength of semi-conductive shielding materials. However, the thermal decomposition of peroxide-based crosslinking agents during processing can easily trigger non-uniform and uncontrollable crosslinking reactions. Especially in carbon black systems, the free radical concentration is higher, resulting in a significantly increased risk of scorching. The semi-conductive shielding material undergoes local thermal degradation and carbonization, forming defects such as melt discontinuity, carbon black agglomeration, or microbubbles. This in turn affects the interfacial bonding quality with the insulation layer, increases the risk of electric field distortion and partial discharge, and endangers the insulation stability and operational safety of high-voltage cables. However, solutions to the scorch problem mainly rely on optimizing processing parameters (such as temperature and shear rate), adding crosslinking delay agents, or adjusting the formula structure, but the solution is not very effective.

[0004] Therefore, how to improve the semi-conductive shielding material of high-voltage cables, improve its anti-scorch performance, and take into account the conductive performance and mechanical properties has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] Based on this, the main purpose of the present invention is to provide a semi-conductive shielding material, its preparation method, application and high-voltage cable. In the semi-conductive shielding material system, the present invention introduces a Diels-Alder type dynamic covalent cross-linking structure by adopting a Diels-Alder cross-linking agent composed of a certain mass fraction of furan compounds and maleic acid derivatives to construct a reversible cross-linking network, which can significantly inhibit its scorching phenomenon, improve the conductivity and mechanical properties, and enhance thermal stability, providing a new technical path for the development of high-performance and high-reliability semi-conductive shielding materials.

[0006] In a first aspect of the present application, a semiconductive shielding material is provided, comprising the following components in parts by weight:

[0007] 60-70 parts of base resin, 20-30 parts of carbon black, 5-10 parts of Diels-Alder crosslinker, 1-3 parts of antioxidant, 2-5 parts of dispersant;

[0008] The Diels-Alder crosslinking agent includes furan compounds and maleic acid derivatives.

[0009] In some embodiments, the furan compound includes one or more of furan, 2,5-dihydroxymethylfuran, and polyfuran ether.

[0010] In some embodiments, the maleic acid derivative comprises bismaleimide and / or maleate.

[0011] In some embodiments, the maleimide includes one or more of N,N′-m-phenylene bismaleimide and N,N′-(p-phenylene)bismaleimide.

[0012] In some embodiments, the maleate includes one or more of dimethyl maleate, diethyl maleate, and dibutyl maleate.

[0013] In some embodiments, the molar ratio of the maleic acid derivative to the furan compound is 1:5-5:1.

[0014] In some embodiments, the base resin includes one or more of ethylene-butyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-vinyl acetate copolymer.

[0015] In some embodiments, the antioxidant includes one or more of a phenolic antioxidant, an amine antioxidant, and a thioether antioxidant.

[0016] In some embodiments, the antioxidant is a phenolic antioxidant.

[0017] In some embodiments, the phenolic antioxidant comprises antioxidant 300 .

[0018] In some embodiments, the dispersant includes one or more of a nonionic surfactant, polyvinyl pyrrolidone, and an amide surfactant.

[0019] In some embodiments, the nonionic surfactant includes a fatty acid ester surfactant.

[0020] In some embodiments, the amide surfactant includes ethylene bisstearamide.

[0021] In some embodiments, the dispersant is polyvinyl pyrrolidone or ethylene bisstearamide.

[0022] In a second aspect, the present application provides a method for preparing the semiconductive shielding material according to the above technical solution, comprising:

[0023] The components are melt-blended, hot-pressed and cross-linked, and granulated to prepare the high-voltage cable semi-conductive shielding material.

[0024] In some embodiments, the melt blending conditions include: temperature of 120-150° C.; rotation speed of 30-80 rpm; and time of 5-15 min.

[0025] In some embodiments, the conditions for hot-press cross-linking include: a temperature of 150-180° C., a pressure of 5-15 MPa, and a time of 5-15 min.

[0026] In some embodiments, the step of melt-blending the components further includes a pretreatment step.

[0027] In some embodiments, the pretreatment step includes drying the components.

[0028] In a third aspect, the present application provides an application of the semi-conductive shielding material described in the above technical solution or a semi-conductive shielding material prepared by the preparation method described in the above technical solution in the preparation of high-voltage cables.

[0029] In a fourth aspect of the present application, a high-voltage cable is provided, comprising the semi-conductive shielding material described in the above technical solution or a semi-conductive shielding material prepared by the preparation method described in the above technical solution.

[0030] Compared with traditional technologies, this application has at least the following beneficial effects:

[0031] First, the present application constructs a reversible Diels-Alder type dynamic covalent cross-linking structure by introducing a certain mass fraction of a furan compound and a maleic acid derivative into a semi-conductive shielding material. The structure can dynamically decrosslink and improve melt fluidity within the processing temperature range, significantly alleviate the material's tendency to burn, greatly increase the processing window and production stability, improve electrical conductivity and mechanical properties, and enhance thermal stability, providing a new technical path for the development of high-performance and high-reliability semi-conductive shielding materials.

[0032] Secondly, the Diels-Alder type cross-linking structure used in the present invention is derived from structural small molecule furan compounds and maleic acid derivatives. Furan compounds and maleic acid derivatives have excellent thermal oxidation stability and low migration, which can significantly improve the thermal aging life and electrical interface stability of semi-conductive shielding materials; through the unzipping and re-crosslinking behavior of the dynamic cross-linking network during the processing process, the agglomeration tendency of carbon black is significantly reduced, and its dispersibility and network continuity in the matrix resin are improved, forming a more stable conductive network, solving the electric field distortion problem caused by carbon black migration and precipitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 Schematic diagram of the preparation method of semi-conductive shielding material. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with the embodiments and examples. These embodiments and examples are only used to illustrate the present invention and are not used to limit the scope of the invention. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive. It should also be understood that the present invention can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. In addition, in the description below, a large amount of specific details are given in order to provide a more complete understanding of the present invention. It should be understood that the present invention can be implemented without one or more of these details.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] Peroxide cross-linking agents are usually used to induce free radical cross-linking during the processing to improve the thermal stability and mechanical strength of semi-conductive shielding materials. However, the thermal decomposition of peroxide cross-linking agents during the processing process can easily trigger non-uniform and uncontrollable cross-linking reactions, especially in carbon black systems, where the free radical concentration is high and the risk of scorching increases significantly. The semi-conductive shielding material undergoes local thermal degradation and carbonization, forming defects such as melt discontinuity, carbon black agglomeration or microbubbles, increasing the risk of electric field distortion and local discharge, and endangering the insulation stability and operational safety of high-voltage cables. Therefore, the present application introduces a Diels-Alder type dynamic covalent cross-linking structure by using a Diels-Alder cross-linking agent composed of furan compounds and maleic acid derivatives in the semi-conductive shielding material, which can significantly inhibit the scorching phenomenon of the semi-conductive shielding material and improve the conductive performance and mechanical properties, providing a new technical path for the development of high-performance and high-stability semi-conductive shielding materials.

[0038] In a first aspect of the present application, a semiconductive shielding material is provided, comprising the following components in parts by weight:

[0039] 60-70 parts of base resin, 20-30 parts of carbon black, 5-10 parts of Diels-Alder crosslinker, 1-3 parts of antioxidant, 2-5 parts of dispersant;

[0040] The Diels-Alder crosslinking agent includes furan compounds and maleic acid derivatives.

[0041] The semi-conductive shielding material described in the present application uses a Diels-Alder crosslinker composed of a certain mass fraction of furan compounds and maleic acid derivatives, and introduces a Diels-Alder type dynamic covalent crosslinking structure, which can significantly inhibit the scorching phenomenon of the semi-conductive shielding material and improve the conductive performance and mechanical properties.

[0042] The Diels-Alder crosslinker described in this application refers to a functional small molecule or oligomer that can undergo an addition reaction with a dienophile / dienophile through a Diels-Alder reaction to form a crosslinked network.

[0043] In some embodiments, the furan compound includes one or more of furan, 2,5-dihydroxymethylfuran, and polyfuran ether.

[0044] In some embodiments, the maleic acid derivative comprises bismaleimide and / or maleate.

[0045] In some embodiments, the bismaleimide includes one or more of N,N′-m-phenylene bismaleimide and N,N′-(p-phenylene)bismaleimide.

[0046] In some embodiments, the maleate includes one or more of dimethyl maleate, diethyl maleate, and dibutyl maleate.

[0047] In some embodiments, the molar ratio of the maleic acid derivative to the furan compound is 1:5-5:1, and can be 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1 or 5:1.

[0048] In some embodiments, the matrix resin comprises one or more of ethylene-butyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-vinyl acetate copolymer. The polar ester groups introduced into the matrix resin's molecular structure facilitate uniform dispersion of the conductive carbon black within the matrix, improving the continuity and thermal stability of the conductive network. Furthermore, the matrix resin's low crystallinity and high segment mobility impart excellent low-temperature toughness and interfacial stress relief capabilities, resulting in superior thermal stability in the operating environment of high-voltage cables.

[0049] In some embodiments, the antioxidant comprises one or more of a phenolic antioxidant, an amine antioxidant, and a thioether antioxidant. In some embodiments, the antioxidant is a phenolic antioxidant.

[0050] In some embodiments, the phenolic antioxidant comprises antioxidant 300 .

[0051] In some embodiments, the antioxidant is antioxidant 300.

[0052] In some embodiments, the dispersant includes one or more of a nonionic surfactant, polyvinyl pyrrolidone, and an amide surfactant.

[0053] In some embodiments, the nonionic surfactant includes a fatty acid ester surfactant.

[0054] In some embodiments, the amide surfactant includes ethylene bisstearamide.

[0055] In some embodiments, the dispersant is polyvinyl pyrrolidone or ethylene bisstearamide.

[0056] In some embodiments, the carbon black is a high-purity conductive carbon black having a DBP absorption value of 110-150 mL / 100 g and an ash content of less than 0.2%.

[0057] The present application adopts a Diels-Alder crosslinking agent composed of a certain mass fraction of furan compounds and maleic acid derivatives in the semi-conductive shielding material, introduces a Diels-Alder structural monomer or oligomer with reversible thermal response characteristics, and constructs a controllable dynamic cross-linking network, which can effectively optimize the rheological properties during the processing process, significantly inhibit the scorching phenomenon of the semi-conductive shielding material, inhibit local thermal degradation caused by high temperature, and restore the cross-linking structure after cooling, thereby improving the thermal stability, interface bonding force and long-term operation reliability of the semi-conductive shielding material, improving the mechanical properties and conductive properties of the semi-conductive shielding material, and improving the material processing window, with excellent industrial applicability. Through the unzipping-recrosslinking behavior in the dynamic cross-linking network, the tendency of carbon black agglomeration is significantly reduced, and its dispersibility and network continuity in the matrix resin are improved, meeting the needs of high-performance cable systems.

[0058] A second aspect of the present application provides a method for preparing the semiconductive shielding material according to the first aspect, comprising:

[0059] The components are melt-blended, hot-pressed and cross-linked, and granulated to prepare the high-voltage cable semi-conductive shielding material.

[0060] In some embodiments, the step of melt-blending the components specifically includes: feeding the components into a twin-screw extruder for melt-blending.

[0061] In some embodiments, the melt blending conditions include: temperature of 120-150° C.; rotation speed of 30-80 rpm; and time of 5-15 min.

[0062] In some embodiments, the step of melt blending the components specifically includes: putting the components into a twin-screw extruder for melt blending; the conditions for melt blending include: a temperature of 120-150°C, which can be 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, or 150°C; a rotation speed of 30-80rpm, which can be 30rpm, 40rpm, 50rpm, 60rpm, 70rpm, or 80rpm; and a time of 5-15min, which can be 5min, 6 min, 7 min, 8 min, 9min, 10 min, 11 min, 12min, 13min, 14min, or 15min.

[0063] In some embodiments, the conditions for hot-press crosslinking include: a temperature of 150-180° C., which may be 150° C., 155° C., 160° C., 165° C., 170° C., 175° C., or 180° C.; a pressure of 5-15 MPa, which may be 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, or 15 MPa; and a time of 5-15 min, which may be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min. The melt-blended mixture is heat-treated by hot pressing to cause a Diels-Alder reaction and form a dynamic covalently crosslinked network structure.

[0064] In some embodiments, the granulation step includes: cooling the hot-pressed material to room temperature and granulating it in a granulator.

[0065] In some embodiments, the step of melt-blending the components further includes a pretreatment step.

[0066] In some embodiments, the pretreatment step includes drying the components; the drying step specifically includes drying the components in an oven. The present application removes moisture from the components through pretreatment.

[0067] The preparation method of the semiconductive shielding material described in this application significantly improves the material's electrical conductivity and thermal stability by melt-blending the various components to uniformly distribute the carbon black within the matrix. A Diels-Alder crosslinker composed of a furan compound and a maleic acid derivative forms a dynamic Diels-Alder covalent bond structure. The unzipping and re-crosslinking behavior within the dynamic crosslinking network significantly reduces the carbon black's tendency to agglomerate, improving its dispersion within the matrix resin and network continuity. The resulting semiconductive shielding material exhibits significantly improved scorch resistance and excellent thermal stability.

[0068] The third aspect of the present application provides the use of the semiconductive shielding material described in the first aspect or the semiconductive shielding material prepared by the preparation method described in the second aspect in the preparation of a high-voltage cable.

[0069] In some embodiments, the semiconductive shielding material is used to prepare a semiconductive shielding layer of a high-voltage cable.

[0070] The semi-conductive shielding material has significantly improved anti-scorch performance and excellent industrial applicability. The semi-conductive shielding material of the present application is applied to high-voltage cables to significantly improve the operating stability of the high-voltage cables.

[0071] In a fourth aspect of the present application, a high-voltage cable is provided, comprising the semi-conductive shielding material described in the first aspect or the semi-conductive shielding material prepared by the preparation method described in the second aspect.

[0072] The high-voltage cable prepared by adopting the semi-conductive shielding material has excellent operation stability.

[0073] The embodiments of the present invention will be described in detail below with reference to the examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. For experimental methods in the following examples where specific conditions are not specified, reference is made to the guidance provided in the present invention, and may also be made according to experimental manuals or conventional conditions in the art, or according to conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0074] The meanings of the abbreviations used in the following examples are as follows:

[0075] Ethylene-butyl acrylate copolymer: EBA;

[0076] Ethylene ethyl acrylate copolymer: EEA;

[0077] Polyvinylpyrrolidone: PVP.

[0078] As examples, the following raw materials are sourced from:

[0079] EBA: purchased from Arkema, product number 17BA07;

[0080] EEA: purchased from Arkema, product number 4700;

[0081] Carbon black: purchased from Cabot, model: CSX880.

[0082] Example 1

[0083] The semi-conductive shielding material is composed of the following components in parts by mass:

[0084] 60 parts of base resin (EBA), 30 parts of carbon black, 5 parts of Diels-Alder crosslinker (N,N′-m-phenylene bismaleimide and furan in a molar ratio of 1:5), 3 parts of antioxidant (Antioxidant 300) and 2 parts of dispersant (PVP).

[0085] Preparation method of semi-conductive shielding material Figure 1 As shown, a mixture formed by melt-blending carbon black, a Diels-Alder crosslinking agent, an antioxidant, a dispersant and a matrix resin is sequentially hot-pressed crosslinked and granulated to obtain a semiconductive shielding material.

[0086] Specifically, the preparation method of the semiconductive shielding material comprises the following steps:

[0087] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0088] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 150°C for melt blending at a speed of 30 rpm for 5 min to obtain a blended mixture;

[0089] (3) Hot pressing crosslinking: hot pressing the blended mixture at 180°C and 5 MPa for 5 min to obtain a hot-pressed material;

[0090] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0091] Example 2

[0092] The semi-conductive shielding material is composed of the following components in parts by mass:

[0093] 70 parts of base resin (EEA), 20 parts of carbon black, 6 parts of Diels-Alder crosslinker (dimethyl maleate and 2,5-dihydroxymethylfuran in a molar ratio of 5:1), 2 parts of antioxidant (Antioxidant 300) and 2 parts of dispersant (PVP).

[0094] A method for preparing a semi-conductive shielding material comprises the following steps:

[0095] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0096] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 120°C for melt blending at a speed of 80 rpm for 15 min to obtain a blended mixture;

[0097] (3) Hot pressing crosslinking: hot pressing the blended mixture at 150°C and 15 MPa for 15 min to obtain a hot-pressed material;

[0098] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0099] Example 3

[0100] The semi-conductive shielding material is composed of the following components in parts by mass:

[0101] 60 parts of base resin (EEA), 25 parts of carbon black, 10 parts of Diels-Alder crosslinker (N,N′-(p-phenylene)bismaleimide and polyfuran ether in a molar ratio of 1:1), 1 part of antioxidant (Antioxidant 300) and 4 parts of dispersant (PVP).

[0102] A method for preparing a semi-conductive shielding material comprises the following steps:

[0103] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0104] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 130°C for melt blending at a speed of 70 rpm for 9 minutes to obtain a blended mixture;

[0105] (3) Hot pressing crosslinking: hot pressing the blended mixture at 160°C and 10 MPa for 10 min to obtain a hot-pressed material;

[0106] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0107] Example 4

[0108] The semi-conductive shielding material is composed of the following components in parts by mass:

[0109] 65 parts of base resin (EEA), 25 parts of carbon black, 7 parts of Diels-Alder crosslinker (N,N′-m-phenylene bismaleimide and 2,5-dihydroxymethylfuran in a molar ratio of 1:2), 1 part of antioxidant (Antioxidant 300) and 2 parts of dispersant (PVP).

[0110] A method for preparing a semi-conductive shielding material comprises the following steps:

[0111] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0112] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 130°C for melt blending at a speed of 70 rpm for 9 min to obtain a blended mixture;

[0113] (3) Hot pressing crosslinking: hot pressing the blended mixture at 160°C and 10 MPa for 10 min to obtain a hot-pressed material;

[0114] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0115] Example 5

[0116] The semi-conductive shielding material is composed of the following components in parts by mass:

[0117] 62 parts of base resin (EEA), 23 parts of carbon black, 8 parts of Diels-Alder crosslinker (diethyl maleate and furan in a molar ratio of 2:1), 2 parts of antioxidant (Antioxidant 300) and 5 parts of dispersant (PVP).

[0118] A method for preparing a semi-conductive shielding material comprises the following steps:

[0119] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0120] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 130°C for melt blending at a speed of 70 rpm for 9 minutes to obtain a blended mixture;

[0121] (3) Hot pressing crosslinking: hot pressing the blended mixture at 160°C and 10 MPa for 10 min to obtain a hot-pressed material;

[0122] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0123] Example 6

[0124] The components of the semiconductive shielding material of Example 6 are substantially the same as those of Example 1, except that the N,N′-m-phenylene bismaleimide in the Diels-Alder crosslinker is replaced with the same molar amount of dibutyl maleate.

[0125] A semiconductive shielding material was prepared according to the preparation method of Example 1.

[0126] Example 7

[0127] The components of the semiconductive shielding material of Example 7 are substantially the same as those of Example 1, except that the N,N′-m-phenylene bismaleimide in the Diels-Alder crosslinking agent is replaced with the same molar amount of dimethyl maleate.

[0128] A semiconductive shielding material was prepared according to the preparation method of Example 1.

[0129] Example 8

[0130] The components of the semiconductive shielding material of Example 8 are substantially the same as those of Example 1, except that the N,N′-m-phenylene bismaleimide in the Diels-Alder crosslinker is replaced with the same molar amount of diethyl maleate.

[0131] A semiconductive shielding material was prepared according to the preparation method of Example 1.

[0132] Example 9

[0133] The components of the semiconductive shielding material of Example 9 are substantially the same as those of Example 1, except that the furan in the Diels-Alder crosslinking agent is replaced with the same molar amount of 2,5-dihydroxymethylfuran.

[0134] A semiconductive shielding material was prepared according to the preparation method of Example 1.

[0135] Example 10

[0136] The components of the semiconductive shielding material of Example 10 are substantially the same as those of Example 1, except that the molar ratio of N,N'-m-phenylene bismaleimide to furan in the Diels-Alder crosslinker is replaced with 3:1.

[0137] A semiconductive shielding material was prepared according to the preparation method of Example 1.

[0138] Example 11

[0139] The components of the semiconductive shielding material of Example 11 are substantially the same as those of Example 9, except that the N,N'-m-phenylene bismaleimide in the Diels-Alder crosslinker is replaced with the same molar amount of dibutyl maleate.

[0140] A semiconductive shielding material was prepared according to the preparation method of Example 9.

[0141] Comparative Example 1

[0142] The components of the semiconductive shielding material of Comparative Example 1 are substantially the same as those of Example 1, except that the Diels-Alder crosslinking agent is replaced by an equal mass fraction of a traditional free radical crosslinking agent, dicumyl peroxide.

[0143] A semiconductive shielding material was prepared according to the preparation method of Example 1.

[0144] Specifically:

[0145] The semi-conductive shielding material is composed of the following components in parts by mass:

[0146] 60 parts of base resin (EBA), 30 parts of carbon black, 5 parts of crosslinking agent (dicumyl peroxide), 3 parts of antioxidant (Antioxidant 300) and 2 parts of dispersant (PVP).

[0147] A method for preparing a semi-conductive shielding material comprises the following steps:

[0148] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0149] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 150°C for melt blending at a speed of 30 rpm for 5 min to obtain a blended mixture;

[0150] (3) Hot pressing crosslinking: hot pressing the blended mixture at 180°C and 5 MPa for 5 min to obtain a hot-pressed material;

[0151] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0152] Comparative Example 2

[0153] The components of the semiconductive shielding material of Comparative Example 2 are substantially the same as those of Example 2, except that the amount of the Diels-Alder crosslinking agent used is 2 parts, and the amount of the carbon black used is 24 parts.

[0154] A semiconductive shielding material was prepared according to the preparation method of Example 2.

[0155] Specifically:

[0156] The semi-conductive shielding material is composed of the following components in parts by mass:

[0157] 70 parts of base resin (EEA), 24 parts of carbon black, 2 parts of Diels-Alder crosslinker (dimethyl maleate and 2,5-dihydroxymethylfuran in a molar ratio of 5:1), 2 parts of antioxidant (Antioxidant 300) and 2 parts of dispersant (PVP).

[0158] A method for preparing a semi-conductive shielding material comprises the following steps:

[0159] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0160] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 120°C for melt blending at a speed of 80 rpm for 15 min to obtain a blended mixture;

[0161] (3) Hot pressing crosslinking: hot pressing the blended mixture at 150°C and 15 MPa for 15 min to obtain a hot-pressed material;

[0162] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0163] Comparative Example 3

[0164] The components of the semiconductive shielding material of Comparative Example 3 are substantially the same as those of Example 3, except that the amount of the Diels-Alder crosslinking agent is 20 parts, the amount of the base resin is 50 parts, and the amount of carbon black is 15 parts.

[0165] A semiconductive shielding material was prepared according to the preparation method of Example 3.

[0166] Specifically,

[0167] The semi-conductive shielding material is composed of the following components in parts by mass:

[0168] 50 parts of base resin (EEA), 15 parts of carbon black, 20 parts of Diels-Alder crosslinker (bismaleimide and polyfuran ether in a molar ratio of 1:1), 1 part of antioxidant (Antioxidant 300) and 4 parts of dispersant (PVP).

[0169] A method for preparing a semi-conductive shielding material comprises the following steps:

[0170] (1) Raw material pretreatment: Take each component by mass and place them in a 60°C oven for 6 hours to remove moisture from the raw materials to obtain pretreated raw materials;

[0171] (2) Melt blending: The pretreated raw materials were put into a twin-screw extruder at 130°C for melt blending at a speed of 70 rpm for 9 minutes to obtain a blended mixture;

[0172] (3) Hot pressing crosslinking: hot pressing the blended mixture at 160°C and 10 MPa for 10 min to obtain a hot-pressed material;

[0173] (4) Granulation: The hot-pressed material is cooled to room temperature, cut into small pieces, and granulated by a granulator to obtain a semi-conductive shielding material.

[0174] Test example

[0175] (1) Mechanical and electrical conductivity test:

[0176] The semi-conductive shielding materials of Examples 1-11 and Comparative Examples 1-3 were each prepared into sheet materials via a hot press process for testing and characterization of their structure and performance. The hot press process involved placing each finished semi-conductive shielding material into a Labtech flatbed vulcanizer, setting the upper and lower platen temperatures to 180°C, preheating for 6 minutes, exhausting the material eight times, each for 10 seconds, then hot pressing for 15 minutes, followed by a final cooling period of 4 minutes before ejecting the material from the mold.

[0177] The mechanical properties and electrical conductivity of the board are tested using GB / T1040.2 and GB / T 3048.3 standards respectively.

[0178] Scorch resistance test of the plate: The scorch resistance of the plate was evaluated using a rotational rheometer. The dynamic test mode was selected as the small-amplitude oscillation shear mode, the test strain was constant at 1%, the temperature was set at 160°C, and the shear frequencies were set to 0.628, 1.0, 2.15, and 6.81 rad / s. -1 The intersection of the loss factors of the four curves is the gel point, and the corresponding time is the anti-scorch time.

[0179] The mechanical properties, electrical conductivity and scorch resistance of the plates prepared from the semi-conductive shielding materials of Examples 1-11 and Comparative Examples 1-3 are shown in Table 1.

[0180] The results in Table 1 show that:

[0181] Compared with Comparative Examples 1-3, Examples 1-11 have higher tensile strength, elongation at break, resistivity at room temperature (23°C), resistivity at high temperature (90°C), and longer anti-scorch time. The tensile strength is 16.8-19.8 MPa, the elongation at break is 256.3-298.5%, and the resistivity at 23°C is 11.7-15.9. , 90℃ resistivity is 95.4-132.8 The anti-scorch time is 62.1-92.8 minutes. The use of the Diels-Alder crosslinker in this application can significantly improve the crosslinking density and conductive path of the semi-conductive shielding material, and significantly improve the anti-scorch performance, conductive performance and mechanical properties of the semi-conductive shielding material.

[0182] Compared with the conventional diisopropylbenzene peroxide crosslinker used in Comparative Example 1, the dynamic crosslinker composed of bismaleimide and furan is used in Example 1, and its scorch resistance, electrical conductivity and mechanical properties are significantly improved. The scorch resistance time is increased by 347%, the resistivity at 90°C is reduced by 64.5%, the resistivity at 23°C is reduced by 29.4%, the tensile strength is increased by 31%, and the elongation at break is not much different. It can be seen that the Diels-Alder reaction of bismaleimide and furan introduces thermally reversible crosslinking points, which form a three-dimensional crosslinked network structure between polymer chains by generating stable covalent bonds. This structure can effectively enhance the tensile strength of the material. At the same time, the three-dimensional crosslinked structure formed can form more conductive paths between carbon black particles. These crosslinking points can provide stable mechanical support, so that the contact between carbon black particles is maintained for a longer time, thereby reducing the breakage of the conductive path or the increase in resistance during the passage of current, thereby showing better electrical conductivity. Compared with the conventional diisopropylbenzene peroxide crosslinker, the Diels-Alder crosslinker used in this application can significantly improve the scorch resistance, electrical conductivity and mechanical properties of the material.

[0183] Compared to Comparative Example 2, which used 2 parts Diels-Alder crosslinker and 24 parts carbon black, Example 2, which used 6 parts Diels-Alder crosslinker and 20 parts carbon black, significantly improved scorch resistance, electrical conductivity, and mechanical properties. The scorch resistance time was increased by 115%, the resistivity at 90°C was reduced by 65.9%, the resistivity at 23°C was reduced by 29.6%, the elongation at break was increased by 32.9%, and the tensile strength was increased by 49.6%. This indicates that, given the same total mass of Diels-Alder crosslinker and carbon black, the use of 5-10 parts of Diels-Alder crosslinker in this application can improve the crosslinking density and conductive path of the semiconductive shielding material, significantly enhancing the scorch resistance, electrical conductivity, and mechanical properties of the semiconductive shielding material, compared to using a smaller amount of Diels-Alder crosslinker.

[0184] Compared to Comparative Example 3, which used 20 parts of Diels-Alder crosslinker, 50 parts of base resin, and 15 parts of carbon black, Example 3, which used 10 parts of Diels-Alder crosslinker, 60 parts of base resin, and 20 parts of carbon black, significantly improved its scorch resistance, electrical conductivity, and mechanical properties. The scorch resistance time increased by 31.2%, the 90°C resistivity decreased by 65.7%, the 23°C resistivity decreased by 38.2%, the elongation at break increased by 18.9%, and the tensile strength increased by 37.6%. This indicates that, compared to using a larger amount of Diels-Alder crosslinker and smaller amounts of carbon black and base resin, the present invention uses 5-10 parts by weight of Diels-Alder crosslinker, 20-30 parts by weight of carbon black, and 60-70 parts by weight of base resin, which can improve the crosslinking density and conductive path of the semiconductive shielding material, significantly enhancing the scorch resistance, electrical conductivity, and mechanical properties of the semiconductive shielding material.

[0185] Comparing Example 1 with Examples 6-8, it can be seen that the maleic acid derivatives in the Diels-Alder crosslinker of the present application using dibutyl maleate or dimethyl maleate have better scorch resistance time, 90°C resistivity, 23°C resistivity and tensile strength than those using diethyl maleate and N,N′-m-phenylene bismaleimide.

[0186] Comparing Example 1 and Example 9, it can be seen that the furan compound in the Diels-Alder crosslinker of the present application is 2,5-dihydroxymethylfuran, and its anti-scorch performance, conductive performance and mechanical properties are better than those of furan.

[0187] Table 1 Test results of mechanical properties, electrical conductivity and scorch resistance of the board

[0188]

[0189] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0190] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A semi-conductive shielding material, characterized in that: The composition comprises the following components in parts by weight: 60-70 parts of base resin, 20-30 parts of carbon black, 5-10 parts of Diels-Alder crosslinker, 1-3 parts of antioxidant, 2-5 parts of dispersant; The Diels-Alder crosslinking agent includes furan compounds and maleic acid derivatives.

2. The semiconductive shielding material according to claim 1, characterized in that The furan compound includes one or more of furan, 2,5-dihydroxymethylfuran and polyfuran ether.

3. The semiconductive shielding material according to claim 1, characterized in that The maleic acid derivatives include bismaleimide and / or maleate; Optionally, the maleimide includes one or more of N,N′-m-phenylene bismaleimide and N,N′-(p-phenylene)bismaleimide; Optionally, the maleate includes one or more of dimethyl maleate, diethyl maleate and dibutyl maleate.

4. The semiconductive shielding material according to any one of claims 1 to 3, characterized in that: The molar ratio of the maleic acid derivative to the furan compound is 1:5-5:

1.

5. The semiconductive shielding material according to any one of claims 1, characterized in that: The matrix resin includes one or more of ethylene-butyl acrylate copolymer, ethylene-ethyl acrylate copolymer and ethylene-vinyl acetate copolymer; The antioxidant includes one or more of phenolic antioxidants, amine antioxidants and thioether antioxidants; Optionally, the antioxidant is a phenolic antioxidant; Optionally, the phenolic antioxidant includes antioxidant 300; The dispersant includes one or more of a nonionic surfactant, polyvinyl pyrrolidone, and an amide surfactant; Optionally, the nonionic surfactant includes a fatty acid ester surfactant; Optionally, the amide surfactant includes ethylene bisstearamide; Optionally, the dispersant is polyvinyl pyrrolidone or ethylene bisstearamide.

6. The method for preparing the semiconductive shielding material according to any one of claims 1 to 5, characterized in that: include: The components are melt-blended, hot-pressed and cross-linked, and granulated to prepare the high-voltage cable semi-conductive shielding material.

7. The preparation method according to claim 6, characterized in that The melt blending conditions include: temperature of 120-150°C; rotation speed of 30-80 rpm; time of 5-15 minutes; The conditions for hot pressing cross-linking include: temperature of 150-180° C., pressure of 5-15 MPa, and time of 5-15 min.

8. The preparation method according to claim 6 or 7, characterized in that The step of melt blending the components also includes a pretreatment step; Optionally, the pretreatment step includes drying the components.

9. Use of the semiconductive shielding material according to any one of claims 1 to 5 or the semiconductive shielding material prepared by the preparation method according to any one of claims 6 to 8 in the preparation of high-voltage cables.

10. A high-voltage cable, comprising the semiconductive shielding material according to any one of claims 1 to 5 or the semiconductive shielding material prepared by the preparation method according to any one of claims 6 to 8.

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