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

Abstract

The invention provides a semiconductive shielding material, a preparation method and application thereof, and a cable, and belongs to the technical field of semiconductive shielding materials. The semiconductive shielding material is prepared from the following raw materials in parts by mass: 59.5 to 72 parts of matrix resin, 25 to 35 parts of conductive carbon black, 2 to 5 parts of sulfydryl modified hyperbranched polyester, 0.2 to 1 part of functional additive and 0.5 to 2 parts of cross-linking agent. The sulfydryl-modified hyperbranched polyester with the hyperbranched steric hindrance effect is adopted, the dispersion uniformity of the conductive carbon black is improved under the condition that the filling amount of the conductive carbon black is low through the interaction of sulfydryl and the conductive carbon black and the hyperbranched steric hindrance effect, and the conductivity of the conductive carbon black is improved. The high conductivity, high mechanical property and good processability of the semiconductive shielding material are realized, meanwhile, high-temperature migration is inhibited, and the heat aging resistance is improved.

Description

Technical Field

[0001] This application relates to the field of semiconductive shielding materials technology, and in particular to semiconductive shielding materials, their preparation methods and applications, and cables. Background Technology

[0002] Semiconducting shielding materials, as key materials in cable insulation structures, tightly coat the conductor surface and insulation layer interface. By eliminating microscopic defects at the interface, homogenizing the electric field distribution, and suppressing partial discharge, they provide a fundamental guarantee for the long-term safe operation of cables. Conductive carbon black (CB)-based shielding materials have excellent cost-effectiveness, good polymer compatibility, and mature processing technology, and are widely used in current high-voltage cables.

[0003] However, in traditional conductive carbon black-based shielding materials, CB filler is prone to agglomeration because carbon black particles have a high surface energy (>70 mJ / m²). 2 Furthermore, π-π interactions exist, forming submicron-sized aggregates in the matrix, leading to a significant decrease in dispersion uniformity. To achieve the semiconductor properties of 100-102 Ω·cm in the material, the CB loading needs to be increased. However, increasing the CB loading will cause the following defects: a surge in melt viscosity, resulting in poor extrusion processing performance and easy formation of surface sharkskin defects; carbon black agglomerates act as stress concentration points, severely degrading the material's mechanical properties and aging resistance.

[0004] Surface modification and the addition of toughening agents are commonly used to improve the dispersibility of CB (conductive polymer). However, most of the modifiers currently used are small molecules, such as silane coupling agents. Although silane coupling agents can improve dispersibility in the short term, they are prone to migration and precipitation during high-temperature processing, leading to CB agglomeration and recurrence during service life, and significant changes in volume resistivity after thermal aging. Adding elastomer toughening agents can improve elongation at break, but they easily form island structures, which can disrupt the conductive network and significantly increase resistivity. Therefore, improving the dispersibility of CB in semiconductive shielding materials to enhance their conductivity, mechanical properties, aging resistance, and processability has become an urgent need for the technological upgrading of cable shielding materials. Summary of the Invention

[0005] Based on this, the main objective of this application is to provide a semiconductive shielding material, its preparation method and application, and cables, to improve the dispersibility of conductive carbon black, thereby improving the conductivity, mechanical properties, heat aging resistance and processability of the semiconductive shielding material.

[0006] The first aspect of this application provides a semiconductive shielding material comprising the following raw materials in parts by weight:

[0007] The matrix resin consists of 59.5-72 parts, conductive carbon black of 25-35 parts, mercapto-modified hyperbranched polyester of 2-5 parts, functional additives of 0.2-1 parts, and crosslinking agent of 0.5-2 parts.

[0008] In some embodiments, the structure density of the conductive carbon black is 110-150 mL / 100 g.

[0009] In some embodiments, the conductive carbon black has an ash content of <0.2% by mass.

[0010] In some embodiments, the matrix resin comprises an olefin-acrylate copolymer.

[0011] In some embodiments, the olefin-acrylate copolymer includes at least one of ethylene-butyl acrylate copolymer, ethylene-methyl acrylate copolymer, and ethylene-ethyl acrylate copolymer.

[0012] In some embodiments, the crosslinking agent includes at least one of diisopropylbenzene peroxide and diisopropylbenzene hydrogen peroxide.

[0013] In some embodiments, the functional additives include lubricants and / or antioxidants.

[0014] In some embodiments, the amount of the lubricant used is 0.1-0.5 parts.

[0015] In some embodiments, the amount of the antioxidant is 0.1-0.5 parts.

[0016] In some embodiments, the lubricant includes at least one of zinc stearate, magnesium stearate, calcium stearate, and polyethylene wax.

[0017] In some embodiments, the antioxidant includes at least one of antioxidant 300, antioxidant 1010, antioxidant 1035, antioxidant 2246, and antioxidant 168.

[0018] In some embodiments, the method for preparing the thiol-modified hyperbranched polyester includes the following steps:

[0019] The thiol-modified hyperbranched polyester was prepared by esterification reaction of 3-mercaptopropionic acid with hydroxyl-terminated hyperbranched polyester.

[0020] A second aspect of this application provides a method for preparing the semiconductive shielding material described in the first aspect, comprising the following steps:

[0021] Surface-modified conductive carbon black was prepared by surface modification of conductive carbon black with thiol-modified hyperbranched polyester.

[0022] The surface-modified conductive carbon black, matrix resin and functional additives are mixed and granulated to prepare granular intermediates.

[0023] The semiconductive shielding material is prepared by mixing and crosslinking the particulate intermediate with a crosslinking agent.

[0024] In some embodiments, the step of surface modification of conductive carbon black with thiol-modified hyperbranched polyester includes: ultrasonically dispersing the conductive carbon black and thiol-modified hyperbranched polyester in a solvent.

[0025] In some embodiments, the solvent includes toluene.

[0026] In some implementations, the conditions for ultrasonic dispersion include: ultrasonic power of 200-400W; ultrasonic time of 2-4min.

[0027] In some implementations, the mixing conditions include: a temperature of 170-180°C and a time of 170-25 minutes.

[0028] The third aspect of this application provides the application 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 cables.

[0029] In a fourth aspect of this application, a cable is provided, the raw material of which includes 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.

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

[0031] This application utilizes thiol-modified hyperbranched polyester with hyperbranched steric hindrance effect. Through the interaction between thiol and conductive carbon black and the hyperbranched steric hindrance effect, the dispersibility of conductive carbon black is improved with a lower conductive carbon black filling amount, achieving high conductivity, high mechanical properties and good processability of the semi-conductive shielding material. At the same time, it inhibits high-temperature migration and improves heat aging resistance, providing technical support for ultra-high voltage cable shielding materials. Attached Figure Description

[0032] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 This is a flowchart illustrating the preparation method of the semiconductive shielding material in an embodiment. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are only for illustrating the present application and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application 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 modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. In addition, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0035] 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.

[0036] To address the issue of uneven dispersion of carbon black (CB) in semiconductive shielding materials leading to reduced conductivity, mechanical properties, aging resistance, and processability, this application employs thiol-modified hyperbranched polyester with hyperbranched steric hindrance effect. Through the interaction between thiol groups and conductive carbon black, as well as the hyperbranched steric hindrance effect, high conductivity and good processability of the semiconductive shielding material are achieved with a relatively low conductive carbon black filling amount. Simultaneously, high-temperature migration is suppressed, and heat aging resistance is improved, providing technical support for ultra-high voltage cable shielding materials.

[0037] The first aspect of this application provides a semiconductive shielding material comprising the following raw materials in parts by weight:

[0038] The matrix resin consists of 59.5-72 parts, conductive carbon black of 25-35 parts, mercapto-modified hyperbranched polyester of 2-5 parts, functional additives of 0.2-1 parts, and crosslinking agent of 0.5-2 parts.

[0039] This application employs thiol-modified hyperbranched polyester with hyperbranched steric hindrance effect. Through the interaction between thiol and conductive carbon black and the hyperbranched steric hindrance effect, the conductivity, mechanical properties, aging resistance and processability of the semiconductive shielding material are improved with a lower conductive carbon black filling amount.

[0040] In some embodiments, the structure density of the conductive carbon black is 110-150 mL / 100 g.

[0041] In some embodiments, the conductive carbon black has an ash content of <0.2% by mass.

[0042] In some embodiments, the conductive carbon black in the semiconductive shielding material is 25-35 parts by mass, which can be 25 parts, 27 parts, 30 parts, 32 parts or 35 parts.

[0043] In some embodiments, the matrix resin comprises an olefin-acrylate copolymer.

[0044] In some embodiments, the olefin-acrylate copolymer includes at least one of ethylene-butyl acrylate copolymer (EBA), ethylene-methyl acrylate copolymer (EMA), and ethylene-ethyl acrylate copolymer (EEA).

[0045] In some embodiments, the matrix resin in the semiconductive shielding material comprises 59.5-72 parts by mass, specifically 59.5, 64.5, 69.5, or 72 parts.

[0046] In some embodiments, the crosslinking agent includes at least one of diisopropylbenzene peroxide (BIPB) and diisopropylbenzene hydrogen peroxide (DCP).

[0047] In some embodiments, the crosslinking agent in the semiconductive shielding material is 0.5-2 parts by mass, which can be 0.5 parts, 1 part, 1.5 parts or 2 parts.

[0048] In some embodiments, the functional additives include lubricants and / or antioxidants.

[0049] In some embodiments, the functional additive in the semiconductive shielding material is 0.2-1 parts by mass, which can be 0.2 parts, 0.5 parts, 0.8 parts or 1 part.

[0050] In some embodiments, the amount of the lubricant is 0.1-0.5 parts, which can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts or 0.5 parts.

[0051] In some embodiments, the amount of the antioxidant is 0.1-0.5 parts, which can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts or 0.5 parts.

[0052] In some embodiments, the lubricant includes at least one of zinc stearate, magnesium stearate, calcium stearate, and polyethylene wax.

[0053] In some embodiments, the antioxidant includes at least one of antioxidant 300, antioxidant 1010, antioxidant 1035, antioxidant 2246, and antioxidant 168.

[0054] In some embodiments, the mass fraction of the thiol-modified hyperbranched polyester in the semiconductive shielding material is 2-5 parts, which can be 2 parts, 3 parts, 4 parts or 5 parts.

[0055] In some embodiments, the method for preparing the thiol-modified hyperbranched polyester includes the following steps:

[0056] Thiol-modified hyperbranched polyesters were prepared by esterification of 3-mercaptopropionic acid with hydroxyl-terminated hyperbranched polyesters.

[0057] In some embodiments, the step of esterification reaction of 3-mercaptopropionic acid with hydroxyl-terminated hyperbranched polyester includes:

[0058] Under inert gas protection, a catalyst, hydroxyl-terminated hyperbranched polyester, 3-mercaptopropionic acid and toluene were mixed and stirred to react, and then dried to prepare a mercapto-modified hyperbranched polyester.

[0059] In some embodiments, the inert gas includes nitrogen.

[0060] In some embodiments, the catalyst comprises p-toluenesulfonic acid.

[0061] In some embodiments, the molar ratio of the catalyst, hydroxyl-terminated hyperbranched polyester, and 3-mercaptopropionic acid is 0.009:0.03:0.43.

[0062] In some embodiments, the hydroxyl-terminated hyperbranched polyester has 40-50 mol of hydroxyl groups, a hydroxyl value of 520 mg KOH / g, an acid value of less than 30 mg KOH / g, and a molecular weight of 5200 g / mol.

[0063] In some embodiments, the mixing and stirring reaction conditions include: a temperature of 170-180°C and a time of 15-25 min.

[0064] A second aspect of this application provides a method for preparing the semiconductive shielding material described in the first aspect, comprising the following steps:

[0065] Surface-modified conductive carbon black was prepared by surface modification of conductive carbon black with thiol-modified hyperbranched polyester.

[0066] The surface-modified conductive carbon black, matrix resin and functional additives are mixed and granulated to prepare granular intermediates.

[0067] The semiconductive shielding material is prepared by mixing and crosslinking the particulate intermediate with a crosslinking agent.

[0068] This application modifies the surface of conductive carbon black using thiol-modified hyperbranched polyester. Through the interaction between thiol and conductive carbon black and the steric hindrance effect of hyperbranching, the conductivity, mechanical properties, aging resistance and processability of the semiconductive shielding material are improved with a lower conductive carbon black filling amount.

[0069] In some embodiments, before the step of mixing the surface-modified conductive carbon black, matrix resin and functional additives, a step of drying the matrix resin, conductive carbon black, mercapto-modified hyperbranched polyester and functional additives is included to remove moisture from the materials.

[0070] In some embodiments, the step of surface modification of conductive carbon black with thiol-modified hyperbranched polyester includes: ultrasonically dispersing the conductive carbon black and thiol-modified hyperbranched polyester in a solvent.

[0071] In some embodiments, the solvent includes toluene.

[0072] In some implementations, the conditions for ultrasonic dispersion include: ultrasonic power of 200-400W; ultrasonic time of 2-4min.

[0073] In some embodiments, after the step of ultrasonically dispersing the conductive carbon black and the mercapto-modified hyperbranched polyester in a solvent, a drying step is further included; the drying temperature may be 100°C.

[0074] In some implementations, the mixing conditions include: a temperature of 170-180°C and a time of 15-25 minutes.

[0075] In some embodiments, after mixing, a drying step is also included; the drying temperature may be 80°C.

[0076] In some embodiments, the crosslinking conditions include a temperature of 170-180°C and a time of 15-25 min.

[0077] The third aspect of this application provides the application 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 cables.

[0078] In a fourth aspect of this application, a cable is provided, the raw material of which includes 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.

[0079] In some embodiments, the cable includes an ultra-high voltage cable.

[0080] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0081] As an example, the raw materials used in the embodiments of this application are as follows:

[0082] Ethylene-butyl acrylate copolymer: purchased from DowDuPont, model Elvaloy® AC 34035;

[0083] Hydroxyl-terminated hyperbranched polyester: purchased from Wuhan Hyperbranched Polymer Technology Co., Ltd., China, model H104;

[0084] Conductive carbon black: purchased from Cabot Corporation, model VXC500, with a structure density of 145 mL / 100 g and a specific surface area of ​​78 m². 2 / g, ash content by mass <0.2%;

[0085] 3-Mercaptopropionic acid: purchased from Aladdin Chemical Reagent Co., Ltd., China, purity ≥98%;

[0086] p-Toluenesulfonic acid: purchased from Aladdin Chemical Reagent Co., Ltd., China, purity ≥98.5%;

[0087] Toluene: purchased from Aladdin Chemical Reagent Co., Ltd., China;

[0088] Anhydrous sodium sulfate: purchased from Aladdin Chemical Reagent Co., Ltd., China, purity ≥99%;

[0089] Zinc stearate: purchased from Aladdin Chemical Reagent Co., Ltd., China;

[0090] Antioxidant 300: Purchased from BASF AG, Germany;

[0091] POE (polyolefin elastomer) toughening agent: purchased from Exxon Chemicals, model POE5171.

[0092] Example 1

[0093] The raw materials for semiconductive shielding materials consist of the following components in parts by weight:

[0094] 64.5 parts of ethylene-butyl acrylate copolymer (matrix resin), 30 parts of conductive carbon black, 4 parts of mercapto-modified hyperbranched polyester, 0.5 parts of functionalizing additives, and 1 part of diisopropylbenzene peroxide (crosslinking agent);

[0095] The functional additives include 0.2 parts zinc stearate and 0.3 parts antioxidant 300;

[0096] The preparation method of thiol-modified hyperbranched polyester is as follows:

[0097] In a nitrogen-protected three-necked flask, 0.03 mol of hydroxyl-terminated hyperbranched polyester, 0.43 mol of 3-mercaptopropionic acid, 1.62 g of p-toluenesulfonic acid catalyst, and 75 mL of toluene were added sequentially. The mixture was stirred at 80 °C for 12 h, then dried over anhydrous sodium sulfate and distilled under reduced pressure to prepare thiol-modified hyperbranched polyester.

[0098] Preparation methods of semiconductive shielding materials, such as Figure 1 As shown, specifically:

[0099] In a nitrogen-protected three-necked flask, 0.03 mol of hydroxyl-terminated hyperbranched polyester, 0.43 mol of 3-mercaptopropionic acid, 1.62 g of p-toluenesulfonic acid catalyst (0.009 mol) and 75 mL of toluene were added sequentially. The mixture was stirred at 80 °C for 12 h, then dried over anhydrous sodium sulfate and distilled under reduced pressure to prepare thiol-modified hyperbranched polyester.

[0100] Ethylene-butyl acrylate copolymer, conductive carbon black, mercapto-modified hyperbranched polyester and functional additives were dried at 65°C for 6 hours to remove moisture;

[0101] Conductive carbon black and mercapto-modified hyperbranched polyester were added to toluene at a mass-to-volume ratio of 0.5 g: 100 mL. The mixture was ultrasonically dispersed for 4 min using an ultrasonic cell disruptor at a power of 400 W and then dried at 100 °C to prepare surface-modified conductive carbon black.

[0102] Ethylene-butyl acrylate copolymer, surface-modified conductive carbon black and functional additives were mixed and put into a torque rheometer for kneading. The kneading temperature was 180℃ and the kneading time was 15min. After kneading, the mixture was cooled, pelletized, and dried in an 80℃ oven to obtain a granular intermediate with a particle size of 1mm.

[0103] The granular intermediate was dried in a constant temperature oven at 70°C for 6 hours. Then, the dried granular intermediate was mixed with a crosslinking agent and crosslinked at 180°C for 25 minutes. The mixture was then placed in a 60°C oven for 10 hours to allow the crosslinking agent to be fully absorbed, thus preparing a semi-conductive shielding material.

[0104] Example 2

[0105] Example 2 has the same raw material composition as Example 1, except that "64.5 parts of ethylene-butyl acrylate copolymer and 30 parts of conductive carbon black" are replaced with "69.5 parts of ethylene-butyl acrylate copolymer and 25 parts of conductive carbon black".

[0106] The semiconductive shielding material was prepared according to the method in Example 1.

[0107] Example 3

[0108] Example 3 has the same raw material composition as Example 1, except that "64.5 parts of ethylene-butyl acrylate copolymer and 30 parts of conductive carbon black" are replaced with "59.5 parts of ethylene-butyl acrylate copolymer and 35 parts of conductive carbon black".

[0109] The semiconductive shielding material was prepared according to the method in Example 1.

[0110] Comparative Example 1

[0111] The raw material composition of Comparative Example 1 is basically the same as that of Example 1, except that "thiol-modified hyperbranched polyester" is replaced with an equal mass fraction of "silane coupling agent KH550".

[0112] The semiconductive shielding material was prepared according to the method in Example 1.

[0113] Comparative Example 2

[0114] The raw material composition of Comparative Example 2 is basically the same as that of Example 1, except that "thiol-modified hyperbranched polyester" is replaced with an equal mass fraction of "POE (polyolefin elastomer) toughening agent".

[0115] The semiconductive shielding material was prepared according to the method in Example 1.

[0116] Comparative Example 3

[0117] The raw material composition of Comparative Example 3 is basically the same as that of Example 1, except that "thiol-modified hyperbranched polyester" is replaced with an equal mass fraction of "silane coupling agent KH580 (3-mercaptopropyltriethoxysilane)".

[0118] The semiconductive shielding material was prepared according to the method in Example 1.

[0119] Comparative Example 4

[0120] The raw material composition of Comparative Example 4 is basically the same as that of Example 1, except that "4 parts of thiol-modified hyperbranched polyester" is replaced with "1.5 parts of thiol-modified hyperbranched polyester".

[0121] The semiconductive shielding material was prepared according to the method in Example 1.

[0122] Experimental Example 1

[0123] The rheological properties of the semiconductive shielding materials prepared in Examples 1-3 and Comparative Examples 1-4 were tested. The semiconductive shielding materials prepared in Examples 1-3 and Comparative Examples 1-4 were hot-pressed at 180℃ to prepare samples, and their electrical properties, mechanical properties and heat aging resistance were tested. The test results are shown in Table 1.

[0124] The test method for electrical performance is as follows: The test is conducted in accordance with the standard GB / T 3048.3-2007. A sample with a diameter of 50 mm is placed in a three-electrode system, and a DC voltage of 500 V is applied for 60 seconds. The stable resistance value is then measured, and the volume resistivity is calculated.

[0125] Mechanical property testing method: The test is carried out according to the standard GB / T 1040.2-2022. The standard dumbbell-shaped specimen is stretched to fracture at a speed of 50 mm / min on an electronic universal testing machine. The stress-strain curve is recorded to calculate the tensile strength and elongation at break.

[0126] Rheological property testing method: The test is conducted according to the standard GB / T 25278-2010. An appropriate amount of granules is tested at 180℃ and different shear rates using a capillary rheometer. The melt flow rate of the material is characterized by measuring the melt pressure and extrusion speed.

[0127] Test method for heat aging resistance: The test is conducted in accordance with the provisions of GB / T 2951.41-2024 on the heat aging test of polyolefin components for cables. The dumbbell-shaped sample is placed in a heat aging test chamber at 135℃ and kept for 100 hours. After being removed and restored, the rate of change of its mechanical and electrical properties is tested.

[0128] Table 1. Performance of Semiconductor Shielding Materials

[0129]

[0130] The results in Table 1 show that, compared with Comparative Examples 1-2, the thiol-modified hyperbranched polyester used in Examples 1-3 of this application exhibits the following improvements: the volume resistivity change rate of the semiconductive shielding material after thermal aging decreased from 85-210% to 16-25%; the elongation at break increased from 98-145% to 190-205%; the tensile strength increased from 15.0-16.2 MPa to 17.8-18.5 MPa; the tensile strength retention rate after aging increased from 73-82% to 87-91%; and the melt flow rate increased from 0.28-0.33 g / 10min to 0.75-0.85 g / 10min. As can be seen, this application utilizes thiol-modified hyperbranched polyester, where the hyperbranched structure exhibits steric hindrance. The interaction between the thiol groups and conductive carbon black disrupts the π-π agglomeration of the conductive carbon black. With a filler content of 25-35 parts by mass, high conductivity of the semi-conductive shielding material is achieved. The conductive carbon black significantly improves melt flow rate and eliminates sharkskin defects caused by high filler content, meeting the continuous high-speed extrusion requirements of ultra-high voltage cables. Simultaneously, the hyperbranched network of the thiol-modified hyperbranched polyester forms an interpenetrating structure with the ethylene-butyl acrylate copolymer resin matrix, constructing a three-tiered stress buffer system of "rigid conductive carbon black - flexible branched chain - elastic resin," significantly improving the mechanical properties of the semi-conductive shielding material and reducing the degradation of mechanical properties after thermal aging. The polymer characteristics of the matrix resin reduce small molecule migration, and the cross-linked network effectively inhibits the high-temperature migration of the conductive carbon black, significantly reducing the risk of conductivity degradation and conductive failure due to thermal aging. The semiconductive shielding material of this application solves the problem of balancing conductivity, processability, heat aging resistance and mechanical properties through topology design, providing an independent solution for shielding materials of 110kV and above UHV cables with performance exceeding that of imported competitors.

[0131] Compared to Comparative Example 1, which used silane coupling agent KH550, Example 1, which used mercapto-modified hyperbranched polyester, exhibited a 44% reduction in volume resistivity, an 81% reduction in resistivity change rate after thermal aging, a 1.1-fold increase in elongation at break, a 14% increase in tensile strength, a 25% increase in tensile strength retention after aging, and a 1.9-fold increase in melt flow rate. This indicates that, compared to using silane coupling agent KH550, the mercapto-modified hyperbranched polyester used in this application effectively prevents conductive carbon black agglomeration and improves the dispersibility of conductive carbon black, thereby significantly improving the conductivity, heat aging resistance, mechanical properties, and rheological properties of the semiconducting shielding material, while also exhibiting strong processability.

[0132] Compared to Comparative Example 2, which used POE toughening agent, Example 1, which used mercapto-modified hyperbranched polyester, exhibited a 98% reduction in volume resistivity, a 92% reduction in resistivity change rate after thermal aging, a 41% increase in elongation at break, a 23% increase in tensile strength, an 11% increase in tensile strength retention after aging, and a 1.2-fold increase in melt flow rate. This indicates that, compared to using POE toughening agent, the mercapto-modified hyperbranched polyester used in this application effectively prevents conductive carbon black agglomeration and improves the dispersibility of conductive carbon black, thereby significantly improving the conductivity, heat aging resistance, mechanical properties, and rheological properties of the semiconducting shielding material, while also exhibiting strong processability.

[0133] Compared to Comparative Example 3, which used the silane coupling agent KH580, Example 1, which used a thiol-modified hyperbranched polyester, exhibited a 33% reduction in volume resistivity, a 64% reduction in resistivity change rate after thermal aging, a 64% increase in elongation at break, a 10% increase in tensile strength, a 17% increase in tensile strength retention after aging, and an 82% increase in melt flow rate. This indicates that although KH580 also contains thiol functional groups and can modify conductive carbon black, its small-molecule linear structure lacks the three-dimensional steric hindrance effect of hyperbranched polymers, failing to effectively disrupt the π-π aggregation of conductive carbon black, resulting in unsatisfactory carbon black dispersion uniformity. Furthermore, the small-molecule silane coupling agent still poses a migration risk during high-temperature processing and long-term service, making the material's thermal aging stability significantly lower than that of the thiol-modified hyperbranched polyester used in this application. This comparative result demonstrates that the steric hindrance effect of the hyperbranched structure is crucial for achieving efficient carbon black dispersion and long-term performance stability.

[0134] Compared to Example 1, Comparative Example 4, by reducing the amount of thiol-modified hyperbranched polyester (from 4 parts by mass to 1.5 parts), resulted in an increase in its volume resistivity from 100 Ω·cm to 320 Ω·cm, an increase in the rate of resistivity change after thermal aging from 16% to 65%, and a significant deterioration in mechanical properties and processing flowability. This indicates that when the amount of thiol-modified hyperbranched polyester is insufficient, it cannot form a complete coating on the conductive carbon black and provide sufficient steric hindrance, leading to carbon black agglomeration. This verifies that maintaining a high mass fraction of thiol-modified hyperbranched polyester is crucial for obtaining a semiconductive shielding material with excellent overall performance.

[0135] 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.

[0136] 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 patent application. 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 patent application should be determined by the appended claims.

Claims

1. A semiconductive shielding material, characterized in that, The raw materials include the following parts by weight: The matrix resin consists of 59.5-72 parts, conductive carbon black of 25-35 parts, mercapto-modified hyperbranched polyester of 2-5 parts, functional additives of 0.2-1 parts, and crosslinking agent of 0.5-2 parts.

2. The semiconductive shielding material according to claim 1, characterized in that, It meets one or more of the following characteristics: (1) The structure degree of the conductive carbon black is 110-150 mL / 100 g; (2) The ash content of the conductive carbon black is <0.2%.

3. The semiconductive shielding material according to claim 1, characterized in that, The matrix resin includes an olefin-acrylate copolymer; Optionally, the olefin-acrylate copolymer includes at least one of ethylene-butyl acrylate copolymer, ethylene-methyl acrylate copolymer, and ethylene-ethyl acrylate copolymer; Optionally, the crosslinking agent includes at least one of diisopropylbenzene peroxide and diisopropylbenzene hydrogen peroxide.

4. The semiconductive shielding material according to claim 1, characterized in that, The functional additives include lubricants and / or antioxidants; Optionally, the amount of the lubricant used is 0.1-0.5 parts; Optionally, the amount of the antioxidant is 0.1-0.5 parts; Optionally, the lubricant includes at least one of zinc stearate, magnesium stearate, calcium stearate, and polyethylene wax; Optionally, the antioxidant includes at least one of antioxidant 300, antioxidant 1010, antioxidant 1035, antioxidant 2246, and antioxidant 168.

5. The semiconductive shielding material according to any one of claims 1-4, characterized in that, The preparation method of the thiol-modified hyperbranched polyester includes the following steps: The thiol-modified hyperbranched polyester was prepared by esterification reaction of 3-mercaptopropionic acid with hydroxyl-terminated hyperbranched polyester.

6. The method for preparing the semiconductive shielding material according to any one of claims 1-5, characterized in that, Includes the following steps: Surface-modified conductive carbon black was prepared by surface modification of conductive carbon black with thiol-modified hyperbranched polyester. The surface-modified conductive carbon black, matrix resin and functional additives are mixed and granulated to prepare granular intermediates. The semiconductive shielding material is prepared by mixing and crosslinking the particulate intermediate with a crosslinking agent.

7. The preparation method according to claim 6, characterized in that, The steps of surface modification of conductive carbon black with thiol-modified hyperbranched polyester include: ultrasonically dispersing conductive carbon black and thiol-modified hyperbranched polyester in a solvent. Optionally, the solvent includes toluene; Optional conditions for ultrasonic dispersion include: ultrasonic power of 200-400W; ultrasonic time of 2-4min.

8. The preparation method according to claim 6, characterized in that, The mixing conditions include: a temperature of 170-180℃ and a time of 15-25 minutes.

9. The application of the semiconductive shielding material as described in any one of claims 1-5 or the semiconductive shielding material prepared by the preparation method as described in any one of claims 6-8 in cables.

10. A cable, characterized in that, The raw materials include the semiconductive shielding material according to any one of claims 1-5 or the semiconductive shielding material prepared by the preparation method according to any one of claims 6-8.

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