Ultrahigh-voltage cable insulating material, preparation method thereof and cable

Abstract

The invention relates to the field of power cable materials, in particular to an ultrahigh-voltage cable insulating material, a preparation method thereof and a cable. The ultrahigh-voltage cable insulating material is prepared from the following raw materials in parts by mass: 80 to 100 parts of polyethylene, 1 to 5 parts of a cross-linking agent, 0.5 to 1 part of a compatilizer and 0.1 to 1 part of an organic molecular semiconductor. According to the ultrahigh-voltage cable insulating material, the organic molecule semiconductor with high electron affinity is introduced into the polyethylene matrix, and free electrons are attracted and fixed through strong static electricity of the organic molecule semiconductor, so that injection, migration and accumulation processes of charges in the cable insulating material are blocked; the problem of space charge accumulation of a cable insulating material in a high-voltage environment is solved from the source, and the insulativity and the long-term operation reliability of the cable insulating material are effectively improved.

Description

Technical Field

[0001] This application relates to the field of power cable materials, and in particular to an ultra-high voltage cable insulation material and its preparation method, as well as the cable. Background Technology

[0002] Ultra-high voltage power cables (≥220kV) are core equipment supporting modern high-capacity, long-distance power transmission networks. Cross-linked polyethylene (XLPE) has become the mainstream material for power cable insulation due to its excellent comprehensive insulation properties, ease of processing, and cost advantages.

[0003] However, under ultra-high voltage direct current or strong alternating current electric field conditions, carrier injection occurs at the electrode interface. Chemical impurities, crystal defects, and additive molecules in traditional cross-linked polyethylene easily form charge traps, trapping charges and accumulating within the insulator to form a space charge layer. The accumulated space charge can cause the local electric field intensity distortion to increase to 1.5-3 times the theoretical value. This distortion not only accelerates the initiation and growth of electrical trees but also triggers partial discharge, ultimately leading to premature breakdown of the insulation layer and poor long-term reliability. Summary of the Invention

[0004] Therefore, it is necessary to provide an ultra-high voltage cable insulation material and its preparation method, as well as the cable, that still have good insulation performance and long-term stability under strong electric field conditions.

[0005] In a first aspect, this application provides an insulation material for ultra-high voltage cables.

[0006] An ultra-high voltage cable insulation material, wherein the raw materials for preparing the ultra-high voltage cable insulation material, by weight parts, include:

[0007] 80 to 100 parts of polyethylene;

[0008] 1 to 5 parts of crosslinking agent;

[0009] Compatibilizer 0.5 to 1 part; and

[0010] 0.1 to 1 part of organic molecular semiconductor.

[0011] In some embodiments, the organic molecular semiconductor comprises one or more of 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetramethyl(4-hexylphenyl)-dithiophene[2,3-d:2',3'-d']-s-indole[1,2-b:5,6-b']dithiophene, [6,6]-phenyl-C61 / C71-butyrate isomethyl ester, and 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride.

[0012] In some embodiments, the compatibilizer includes one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted polystyrene.

[0013] In some embodiments, the polyethylene includes low-density polyethylene.

[0014] In some embodiments, the low-density polyethylene has a density of 0.91 g / cm³. 3 ~0.93g / cm 3 ;

[0015] The melting point of the low-density polyethylene is 110℃~120℃;

[0016] The low-density polyethylene has a melt index of 2 g / 10 min to 3 g / 10 min at 190 °C and 2.16 kg.

[0017] In some embodiments, the crosslinking agent includes one or more of di-tert-butyl peroxide, dicumyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0018] In some embodiments, the raw materials for preparing the ultra-high voltage cable insulation material also include 0.5 to 1 part antioxidant by weight.

[0019] In some embodiments, the antioxidant includes one or more of antioxidant 1010, antioxidant 508T, and antioxidant 300.

[0020] In a second aspect, this application provides a method for preparing the aforementioned ultra-high voltage cable insulation material.

[0021] A method for preparing the above-mentioned ultra-high voltage cable insulation material includes the following steps:

[0022] A base material is prepared by mixing polyethylene, organic molecular semiconductors, and a compatibilizer;

[0023] The base material and the remaining raw materials are mixed and extruded into granules to prepare the ultra-high voltage cable insulation material. In a third aspect, this application provides a cable.

[0024] A cable includes a conductor, an insulation layer, and a semi-conductive shielding layer; the conductor is located inside the insulation layer, and the semi-conductive shielding layer is located on at least one surface of the insulation layer; the insulation layer is made of the above-described ultra-high voltage cable insulation material or an ultra-high voltage cable insulation material prepared by the above-described preparation method.

[0025] The aforementioned ultra-high voltage cable insulation material innovatively introduces organic molecular semiconductors with high electron affinity into the polyethylene matrix. Benefiting from the excellent compatibility between the organic molecular semiconductors and cross-linked polyethylene, the organic molecular semiconductors can be well dispersed within the ultra-high voltage cable insulation material. Even with a small amount added, they can be uniformly dispersed without significantly affecting the insulation performance of the ultra-high voltage cable insulation material. Simultaneously, when charge accumulates within the insulation, the organic molecular semiconductors can capture injected and excited free electrons through strong electrostatic attraction. By using trap energy levels, the captured electrons are difficult to escape from the trap sites, effectively blocking the injection, migration, and accumulation of charge in the ultra-high voltage cable insulation material. This fundamentally solves the problem of space charge accumulation in ultra-high voltage cable insulation materials under high-voltage environments, ultimately effectively improving the insulation performance and long-term reliability of the ultra-high voltage cable insulation material. Detailed Implementation

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0027] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In this application, "at least one" means one or more, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0030] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-to-solid mixtures, and volume percentage for liquid-to-liquid mixtures.

[0031] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0032] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0033] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0034] Ultra-high voltage power cables (≥220kV) are core equipment supporting modern high-capacity, long-distance power transmission networks. Cross-linked polyethylene (XLPE) has become the mainstream material for power cable insulation due to its excellent comprehensive insulation properties, ease of processing, and cost advantages.

[0035] However, under ultra-high voltage direct current or strong alternating current electric field conditions, carrier injection occurs at the electrode interface. Chemical impurities, crystal defects, and additive molecules in traditional cross-linked polyethylene easily form charge traps. The captured charges accumulate within the insulator, forming a space charge layer. The accumulated space charge can cause the local electric field intensity distortion to increase to 1.5-3 times the theoretical value. This distortion not only accelerates the initiation and growth of electrical trees but also triggers partial discharge, ultimately leading to premature breakdown of the insulation layer and poor long-term reliability.

[0036] To suppress space charge, mainstream technical approaches and their drawbacks include: 1) Inorganic nanoparticle doping (magnesium oxide, silicon dioxide, boron nitride, etc.): While deep-level traps can be introduced to capture charges, nanoparticles easily aggregate into micron-sized aggregates, forming interface defects that lead to electric field concentration; simultaneously, it significantly increases dielectric loss, causing insulation heating and aging. 2) Chemically grafted modified matrix resin: The process is complex and costly; insufficient grafting ratio results in limited charge suppression; excessive grafting damages the crystallinity of polyethylene, reducing mechanical strength and tracking resistance. All of these methods have certain drawbacks, necessitating the development of a cross-linked polyethylene insulation material for cables with high-efficiency space charge suppression capabilities, excellent processing stability, and long-term thermal aging performance.

[0037] Based on this, the first aspect of this application provides an ultra-high voltage cable insulation material that still has good insulation performance and long-term stability under strong electric field conditions.

[0038] For example, the raw materials for preparing ultra-high voltage cable insulation materials, by weight, include:

[0039] 80 to 100 parts of polyethylene;

[0040] 1 to 5 parts of crosslinking agent;

[0041] Compatibilizer 0.5 to 1 part; and

[0042] 0.1 to 1 part of organic molecular semiconductor.

[0043] The aforementioned ultra-high voltage cable insulation material innovatively introduces organic molecular semiconductors with high electron affinity into a polyethylene matrix. Benefiting from the excellent compatibility between the organic molecular semiconductors and cross-linked polyethylene, the organic molecular semiconductors can be well dispersed within the ultra-high voltage cable insulation material; that is, even a small amount can achieve uniform dispersion without significantly affecting the insulation performance. Furthermore, when charge accumulates within the insulation, the organic molecular semiconductors can capture injected and excited free electrons through their strong electrostatic attraction, and the trap energy levels prevent the captured electrons from escaping from the trap sites. This coordination mechanism effectively blocks the injection, migration, and accumulation of charge in the ultra-high voltage cable insulation material, fundamentally solving the problem of space charge accumulation in ultra-high voltage cable insulation materials under high-voltage environments, thereby effectively improving the insulation performance and long-term operational reliability of the ultra-high voltage cable insulation material.

[0044] Optionally, the organic molecular semiconductor in the raw materials for preparing ultra-high voltage cable insulation materials, by weight, can be, but is not limited to, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, or other values ​​within the range of 0.1 parts to 1 part. A further increase in the content of organic molecular semiconductors may lead to an increase in the conductivity of the material, which is detrimental to maintaining good insulation performance; furthermore, excessive organic molecular semiconductors may affect the mechanical properties of ultra-high voltage cable insulation materials.

[0045] Optionally, the polyethylene in the raw materials for preparing ultra-high voltage cable insulation materials can be, but is not limited to, 80 parts, 85 parts, 90 parts, 95 parts, 100 parts or other values ​​in the range of 80 to 100 parts by weight.

[0046] Optionally, the crosslinking agent in the raw materials for preparing ultra-high voltage cable insulation materials can be, but is not limited to, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or other values ​​within the range of 1 to 5 parts, by mass.

[0047] Optionally, the compatibilizer in the raw materials for preparing ultra-high voltage cable insulation materials can be, but is not limited to, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, or other values ​​within the range of 0.5 parts to 1 part, by mass.

[0048] In some embodiments, the organic molecular semiconductor includes one or more of 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetramethyl(4-hexylphenyl)-dithiophene[2,3-d:2',3'-d']-s-indole[1,2-b:5,6-b']dithiophene (ITIC, CAS: 1664293-06-4), [6,6]-phenyl-C61 / C71-isomethyl butyrate (PCBM, CAS: 160848-22-6), and 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride (NTCDA, CAS: 81-30-1), all of which have excellent electron affinities of 3.9 eV, 4.2 eV, and 4.0 eV, respectively.

[0049] In some embodiments, the compatibilizer includes one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted polystyrene.

[0050] In some of these embodiments, polyethylene includes low-density polyethylene.

[0051] In some embodiments, the density of low-density polyethylene is 0.91 g / cm³. 3 ~0.93g / cm3 Optionally, the density of low-density polyethylene can be, but is not limited to, 0.91 g / cm³. 3 0.92g / cm 3 0.93g / cm 3 Or 0.91g / cm 3 ~0.93g / cm 3 Other values ​​within the range.

[0052] In some embodiments, the melting point of low-density polyethylene is 110°C to 120°C. Optionally, the melting point of low-density polyethylene can be, but is not limited to, 110°C, 115°C, 120°C, or other values ​​within the range of 110°C to 120°C.

[0053] In some embodiments, the melt index of low-density polyethylene at 190°C and 2.16 kg is 2 g / 10 min to 3 g / 10 min. Optionally, the melt index of low-density polyethylene at 190°C and 2.16 kg can be, but is not limited to, 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, or other values ​​within the range of 2 g / 10 min to 3 g / 10 min.

[0054] In some embodiments, the crosslinking agent includes one or more of di-tert-butyl peroxide, dicumyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0055] In some embodiments, the raw materials for preparing ultra-high voltage cable insulation materials further include 0.5 to 1 part antioxidant by weight. Optionally, the antioxidant in the raw materials for preparing ultra-high voltage cable insulation materials may be, but is not limited to, 0.5, 0.6, 0.7, 0.8, 0.9, 1 part, or other values ​​within the range of 0.5 to 1 part by weight.

[0056] In some embodiments, the antioxidant includes one or more of antioxidant 1010, antioxidant 508T, and antioxidant 300.

[0057] In a second aspect, this application provides a method for preparing the aforementioned ultra-high voltage cable insulation material.

[0058] For example, a method for preparing ultra-high voltage cable insulation material includes the following steps:

[0059] A base material is prepared by mixing polyethylene, organic molecular semiconductors, and a compatibilizer;

[0060] The base material and the remaining raw materials are mixed and extruded into granules to prepare ultra-high voltage cable insulation material.

[0061] In some embodiments, the mixing temperature is 120°C to 150°C. Optionally, the mixing temperature can be, but is not limited to, 120°C, 130°C, 140°C, 150°C, or other values ​​within the range of 120°C to 150°C.

[0062] In some embodiments, the mixing time is 15 min to 20 min. Optionally, the mixing time can be, but is not limited to, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, or other values ​​within the range of 15 min to 20 min.

[0063] In some embodiments, the base material, antioxidant and crosslinking agent are mixed and extruded into granules to prepare ultra-high voltage cable insulation material.

[0064] In some embodiments, polyethylene, organic molecular semiconductors, and compatibilizers are mixed by a compounding process.

[0065] In some embodiments, a twin-screw extruder is used for melt extrusion granulation at a temperature of 260°C to 270°C.

[0066] In a third aspect, this application provides a cable. The cable includes a conductor, an insulation layer, and a semi-conductive shielding layer. The conductor is located inside the insulation layer, and the semi-conductive shielding layer is located on at least one surface of the insulation layer. Furthermore, the insulation layer is made of the aforementioned ultra-high voltage cable insulation material or an ultra-high voltage cable insulation material prepared by the aforementioned method.

[0067] The present application will be further described in detail below with reference to specific embodiments.

[0068] Unless otherwise specified, the raw materials used in the following specific embodiments and comparative examples are all commercially available products; the instruments used are all commercially available products; and the processes used are all conventionally selected by those skilled in the art unless otherwise specified.

[0069] Example 1

[0070] This embodiment provides an ultra-high voltage cable insulation material.

[0071] The raw materials for preparing the ultra-high voltage cable insulation material in this embodiment are as follows:

[0072] 95 parts of low-density polyethylene matrix;

[0073] 0.5 parts of organic molecular semiconductor;

[0074] 1 part compatibilizer;

[0075] 2.5 parts of crosslinking agent; and

[0076] One part antioxidant.

[0077] The organic molecular semiconductor is 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetramethyl(4-hexylphenyl)-dithiophene[2,3-d:2',3'-d']-s-indole[1,2-b:5,6-b']dithiophene (ITIC), the compatibilizer is maleic anhydride-grafted polyethylene (purchased from Dongguan Shanyi Plastics Co., Ltd., model PPW-G-MAH), the antioxidant is antioxidant 1010, and the crosslinking agent is dicumyl peroxide. The density of the low-density polyethylene base material is 0.92 g / cm³. 3 It has a melting point of 115℃, a melt index of 2.5g / 10min at 190℃ and 2.16kg.

[0078] The preparation method of the ultra-high voltage cable insulation material in this embodiment is as follows:

[0079] Weigh and dry the low-density polyethylene, organic molecular semiconductor, compatibilizer, antioxidant and crosslinking agent according to the above mass ratio;

[0080] Low-density polyethylene, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetramethyl(4-hexylphenyl)-dithiophene[2,3-d:2',3'-d']-s-indole[1,2-b:5,6-b']dithiopheneITIC, and maleic anhydride-grafted polyethylene were sequentially placed into a mixer and mixed at a mixing temperature of 130℃, a rotation speed of 400 r / min, and a mixing time of 15 min to obtain the base material;

[0081] The base material, antioxidant 1010, and dicumyl peroxide were sequentially placed into a mixer and mixed at a mixing temperature of 130°C, a rotation speed of 400 r / min, and a mixing time of 10 min to obtain the mixture.

[0082] The mixture is melt-extruded and granulated in a twin-screw extruder at a temperature of 260°C to obtain ultra-high voltage cable insulation material.

[0083] Example 2

[0084] This embodiment provides an ultra-high voltage cable insulation material.

[0085] The raw materials for preparing the ultra-high voltage cable insulation material in this embodiment are as follows:

[0086] 95 parts of low-density polyethylene matrix;

[0087] 0.1 parts of organic molecular semiconductor;

[0088] 1 part compatibilizer;

[0089] 2.5 parts of crosslinking agent; and

[0090] One part antioxidant.

[0091] The specific components of the low-density polyethylene matrix, compatibilizer, crosslinking agent, and antioxidant are consistent with those in Example 1.

[0092] The preparation method of the ultra-high voltage cable insulation material in this embodiment is the same as that in Embodiment 1.

[0093] Example 3

[0094] This embodiment provides an ultra-high voltage cable insulation material.

[0095] The raw materials for preparing the ultra-high voltage cable insulation material in this embodiment are as follows:

[0096] 95 parts of low-density polyethylene matrix;

[0097] 0.3 parts of organic molecular semiconductor;

[0098] 1 part compatibilizer;

[0099] 2.5 parts of crosslinking agent; and

[0100] One part antioxidant.

[0101] The specific components of the low-density polyethylene matrix, compatibilizer, crosslinking agent, and antioxidant are consistent with those in Example 1.

[0102] The preparation method of the ultra-high voltage cable insulation material in this embodiment is the same as that in Embodiment 1.

[0103] Example 4

[0104] This embodiment provides an ultra-high voltage cable insulation material.

[0105] The raw materials for preparing the ultra-high voltage cable insulation material in this embodiment are as follows:

[0106] 95 parts of low-density polyethylene matrix;

[0107] 0.5 parts of organic molecular semiconductor;

[0108] 1 part compatibilizer;

[0109] 2.5 parts of crosslinking agent; and

[0110] One part antioxidant.

[0111] The specific components of the low-density polyethylene matrix, compatibilizer, crosslinking agent, and antioxidant are consistent with those in Example 1.

[0112] The preparation method of the ultra-high voltage cable insulation material in this embodiment is the same as that in Embodiment 1.

[0113] Example 5

[0114] This embodiment provides an ultra-high voltage cable insulation material.

[0115] The raw materials for preparing the ultra-high voltage cable insulation material in this embodiment are as follows:

[0116] 95 parts of low-density polyethylene matrix;

[0117] 0.5 parts of organic molecular semiconductor;

[0118] 1 part compatibilizer;

[0119] 2.5 parts of crosslinking agent; and

[0120] One part antioxidant.

[0121] The organic molecular semiconductor is [6,6]-phenyl-C61 / C71-isomethyl butyrate (PCBM), the compatibilizer is maleic anhydride-grafted polyethylene, the antioxidant is antioxidant 1010, and the crosslinking agent is dicumyl peroxide. The density of the low-density polyethylene base material is 0.92 g / cm³. 3 It has a melting point of 115℃, a melt index of 2.5g / 10min at 190℃ and 2.16kg.

[0122] The preparation method of the ultra-high voltage cable insulation material in this embodiment is as follows:

[0123] Weigh and dry the low-density polyethylene, organic molecular semiconductor, compatibilizer, antioxidant and crosslinking agent according to the above mass ratio;

[0124] Low-density polyethylene, [6,6]-phenyl-C61 / C71-butyrate isomethyl ester PCBM, and maleic anhydride-grafted polyethylene were sequentially placed into a mixer and mixed at a mixing temperature of 130℃, a rotation speed of 400r / min, and a mixing time of 15min to obtain the base material.

[0125] The base material, antioxidant 1010, and dicumyl peroxide were sequentially placed into a mixer and mixed at a mixing temperature of 130°C, a rotation speed of 400 r / min, and a mixing time of 10 min to obtain the mixture.

[0126] The mixture is melt-extruded and granulated in a twin-screw extruder at a temperature of 260°C to obtain ultra-high voltage cable insulation material.

[0127] Example 6

[0128] This embodiment provides an ultra-high voltage cable insulation material.

[0129] The raw materials for preparing the ultra-high voltage cable insulation material in this embodiment are as follows:

[0130] 95 parts of low-density polyethylene matrix;

[0131] 0.5 parts of organic molecular semiconductor;

[0132] 1 part compatibilizer;

[0133] 2.5 parts of crosslinking agent; and

[0134] One part antioxidant.

[0135] The organic molecular semiconductor is 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride (NTCDA), the compatibilizer is maleic anhydride-grafted polyethylene, the antioxidant is antioxidant 1010, and the crosslinking agent is dicumyl peroxide. The density of the low-density polyethylene base material is 0.92 g / cm³. 3 It has a melting point of 115℃, a melt index of 2.5g / 10min at 190℃ and 2.16kg.

[0136] The preparation method of the ultra-high voltage cable insulation material in this embodiment is as follows:

[0137] Weigh and dry the low-density polyethylene, organic molecular semiconductor, compatibilizer, antioxidant and crosslinking agent according to the above mass ratio;

[0138] Low-density polyethylene, 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride (NTCDA), and maleic anhydride-grafted polyethylene were sequentially placed into a mixer and mixed at a mixing temperature of 130°C, a rotation speed of 400 r / min, and a mixing time of 15 min to obtain the base material.

[0139] The base material, antioxidant 1010, and dicumyl peroxide were sequentially placed into a mixer and mixed at a mixing temperature of 130°C, a rotation speed of 400 r / min, and a mixing time of 10 min to obtain the mixture.

[0140] The mixture is melt-extruded and granulated in a twin-screw extruder at a temperature of 260°C to obtain ultra-high voltage cable insulation material.

[0141] Comparative Example 1

[0142] This comparative example provides an ultra-high voltage cable insulation material.

[0143] The raw materials used to prepare the ultra-high voltage cable insulation material in this comparative example are as follows:

[0144] 95 parts of low-density polyethylene matrix;

[0145] 1 part compatibilizer;

[0146] 2.5 parts of crosslinking agent; and

[0147] One part antioxidant.

[0148] The specific components of the low-density polyethylene matrix, compatibilizer, crosslinking agent, and antioxidant are consistent with those in Example 1.

[0149] The preparation method of the ultra-high voltage cable insulation material in this comparative example is as follows:

[0150] Weigh and dry the low-density polyethylene, compatibilizer, antioxidant, and crosslinking agent according to the above mass ratios.

[0151] Low-density polyethylene and maleic anhydride-grafted polyethylene were sequentially placed into a mixer and mixed at a mixing temperature of 130°C, a rotation speed of 400 r / min, and a mixing time of 15 min to obtain the base material.

[0152] The base material, antioxidant 1010, and dicumyl peroxide were sequentially placed into a mixer and mixed at a mixing temperature of 130°C, a rotation speed of 400 r / min, and a mixing time of 10 min to obtain the mixture.

[0153] The mixture is melt-extruded and granulated in a twin-screw extruder at a temperature of 260°C to obtain ultra-high voltage cable insulation material.

[0154] Performance testing

[0155] The ultra-high voltage cable insulation materials obtained in Examples 1-6 and Comparative Example 1 were placed in a mold and pressed into thin sheet test samples using a flat vulcanizing machine. The temperature of the flat vulcanizing machine was controlled at 140°C, the time was 15 minutes, the pressure was 10 MPa, and the test sample was 10 cm long, 3 cm wide, and 1 mm thick.

[0156] The DC breakdown field strength of the test samples of each embodiment and comparative example was measured at 25℃, 50℃, and 100℃. During the measurement, a uniform voltage increase method was adopted, with a voltage increase rate of 0.5kV / s until the sample was broken down, and the breakdown voltage was recorded. The cross-linked polyethylene insulation materials of each embodiment and comparative example were suspended in a thermo-oxidative aging chamber with a blower and left to stand for 1 month. The breakdown strength was then measured to evaluate their long-term reliability. The dielectric constant and mechanical properties of the test samples of each embodiment and comparative example at room temperature were tested. The test results are shown in Table 1 below. The breakdown strength test was performed according to GB / T 31838.6-2021, the dielectric constant test was performed according to GB / T 1040.2-2006, and the mechanical property test was performed according to GB / T 1040.2-2006.

[0157] Table 1. Electrical insulation properties of the ultra-high voltage cable insulation materials in the above embodiments and comparative examples.

[0158]

[0159] As shown in Table 1, the ultra-high voltage cable insulation material of the embodiment exhibits high breakdown strength and dielectric constant. After one month of thermo-oxidative aging at 100°C, its breakdown strength remains at approximately 90%, with minimal impact on mechanical properties. Its tensile strength, elongation at break, and elongation under heat load are almost at the same level as Comparative Example 1, demonstrating good electrical insulation and long-term stability. Furthermore, it can be seen that the breakdown strength of the insulation material increases with increasing organic molecular semiconductor content, indicating that the deep trapping effect of the organic molecular semiconductor can prevent trapped electrons from escaping from the trap sites. However, when the organic molecular semiconductor content further increases, the breakdown strength of the insulation material decreases. This may be because excessive organic molecular semiconductors increase the conductivity of the material, thereby reducing its electrical insulation performance.

[0160] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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, they should be considered to be within the scope of this specification.

[0161] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. An ultra-high voltage cable insulation material, characterized in that, The raw materials for preparing the ultra-high voltage cable insulation material, by weight, include: 80 to 100 parts of polyethylene; 1 to 5 parts of crosslinking agent; Compatibilizer 0.5 to 1 part; and 0.1 to 1 part of organic molecular semiconductor.

2. The ultra-high voltage cable insulation material according to claim 1, characterized in that, The organic molecular semiconductor includes one or more of 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetramethyl(4-hexylphenyl)-dithiophene[2,3-d:2',3'-d']-s-indole[1,2-b:5,6-b']dithiophene, [6,6]-phenyl-C61 / C71-butyrate isomethyl ester, and 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride.

3. The ultra-high voltage cable insulation material according to claim 1, characterized in that, The compatibilizer includes one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted polystyrene.

4. The ultra-high voltage cable insulation material according to claim 1, characterized in that, The polyethylene includes low-density polyethylene.

5. The ultra-high voltage cable insulation material according to claim 4, characterized in that, The density of the low-density polyethylene is 0.91 g / cm³. 3 ~0.93g / cm 3 ; and / or The low-density polyethylene has a melting point of 110℃~120℃; and / or The low-density polyethylene has a melt index of 2 g / 10 min to 3 g / 10 min at 190 °C and 2.16 kg.

6. The ultra-high voltage cable insulation material according to claim 1, characterized in that, The crosslinking agent includes one or more of di-tert-butyl peroxide, dicumyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

7. The ultra-high voltage cable insulation material according to any one of claims 1 to 6, characterized in that, The raw materials for preparing the ultra-high voltage cable insulation material also include 0.5 to 1 part antioxidant by weight.

8. The ultra-high voltage cable insulation material according to claim 7, characterized in that, The antioxidants include one or more of antioxidants 1010, antioxidant 508T, and antioxidant 300.

9. A method for preparing the ultra-high voltage cable insulation material according to any one of claims 1 to 8, characterized in that, Includes the following steps: A base material is prepared by mixing polyethylene, organic molecular semiconductors, and a compatibilizer; The base material and the remaining raw materials are mixed and extruded into granules to prepare the ultra-high voltage cable insulation material.

10. A cable, characterized in that, It includes a conductor, an insulating layer, and a semi-conductive shielding layer; the conductor is located inside the insulating layer, and the semi-conductive shielding layer is located on at least one surface of the insulating layer; the insulating layer is made of the ultra-high voltage cable insulating material according to any one of claims 1 to 8 or the ultra-high voltage cable insulating material prepared by the preparation method according to claim 9.