CN-122011559-A - Compression-resistant insulating power cable material, preparation method and power cable

Abstract

The invention relates to the technical field of power cable insulating materials, and discloses a compression-resistant insulating power cable material, a preparation method and a power cable, the insulating material comprises low density polyethylene, ethylene propylene diene monomer, N' -m-phenylene bismaleimide, 2-mercaptobenzimidazole, zinc stearate, zinc methacrylate and dicumyl peroxide. In the preparation process, N, N' -m-phenylene bismaleimide and 2-mercaptobenzimidazole undergo an in-situ addition reaction to generate a macromolecular crosslinked precursor, so that free mercapto masking is realized. The precursor and zinc methacrylate coordinate to form polar nodes, and after crosslinking and solidification, a homogeneous crosslinked network containing electron deep traps and dynamic sacrificial bonds is constructed. The invention effectively inhibits irreversible slip and space charge accumulation of a polymer chain segment in an insulator under the condition of no inorganic filler, so that the cable material has high compression resistance, low creep, high electrical strength and long-acting thermal oxidation aging resistance.

Inventors

• Shang Chaonan
• XU GUANGYU
• ZONG XUAN
• WU QIANG
• WANG SHIQI
• JIANG RUIYING

Assignees

• 江苏宇久电缆科技有限公司

Dates

Publication Date

20260512

Application Date

20260416

Claims (10)

1. 1. The compression-resistant insulating power cable material is characterized by being prepared from the following raw materials in parts by weight: 70-90 parts of low-density polyethylene; 10-30 parts of ethylene propylene diene monomer rubber; 1.0-2.5 parts of N, N' -m-phenylene bismaleimide; 0.5-1.5 parts of 2-mercaptobenzimidazole; 0.5-1.5 parts of zinc stearate; 2.0-5.0 parts of zinc methacrylate; 1.0-2.0 parts of dicumyl peroxide.
2. 2. The crush-resistant insulated power cable material according to claim 1, wherein the low-density polyethylene has a reference density of 0.922g/cm 3 at 20 ℃ and a melt flow rate of 2.0g/10min at 190 ℃ and a standard load of 2.16 kg.
3. 3. The pressure-resistant insulated power cable material according to claim 1, wherein the ethylene-propylene-diene monomer has a main chain of ethylene structural unit of 70% by mass, the third monomer 5-ethylidene-2-norbornene structural unit has a Mooney viscosity ML (1+4) at 125 ℃ of 65.
4. 4. The pressure-resistant insulated power cable material according to claim 1, wherein the melting point range of the N, N' -m-phenylene bismaleimide is 198-201 ℃, the purity is more than 98.0%, the active oxygen mass fraction of the dicumyl peroxide is more than 5.8%, the half life period is 10 hours at 115 ℃, and the heating decrement of the 2-mercaptobenzimidazole is less than 0.3%.
5. 5. A method for preparing a compression-resistant insulated power cable material according to any one of claims 1-4, comprising the steps of: S1, putting low-density polyethylene, ethylene propylene diene monomer, N' -m-phenylene bismaleimide, 2-mercaptobenzimidazole and zinc stearate into an internal mixer, setting the rotation speed of a rotor of the internal mixer, starting a circulating cooling water system, controlling the rubber discharging temperature, maintaining high-shearing constant-temperature mixing, and promoting the system to perform in-situ masking reaction; S2, directly adding zinc methacrylate into the internal mixing chamber without stopping, adjusting the temperature, maintaining, continuing mixing, and promoting the system to construct coordination nodes in situ; s3, reducing the rotation speed of the internal mixer to reduce the temperature of the materials, adding dicumyl peroxide, and discharging rubber after low-shear mixing; And S4, feeding the material obtained in the step S3 into a single screw extruder, extruding at the barrel temperature of 90-105 ℃, and granulating and drying to obtain the crosslinkable insulating material particles.
6. 6. The method for preparing the compression-resistant insulated power cable material according to claim 5, wherein in the step S1, the rotation speed of a rotor of the internal mixer is set to be 50-70 r/min, and a circulating cooling water system with the set water temperature of 20-30 ℃ is started to control the glue discharging temperature of the material in a matching manner.
7. 7. The method for preparing a compression-resistant insulated power cable material according to claim 5, wherein in the step S1, the high-shear constant-temperature mixing is maintained for 5-8 min, and the glue discharging temperature is 125-135 ℃.
8. 8. The method for preparing a compressive insulating power cable material according to claim 5, wherein in the step S2, the continuous mixing time is 3-5 min after zinc methacrylate is added, and the temperature is reduced to and maintained at 115-125 ℃.
9. 9. The preparation method of the compression-resistant insulated power cable material according to claim 5, wherein in the step S3, the time of low-shear mixing is 2-3 min, and the temperature of the material is reduced to 90-110 ℃.
10. 10. The power cable is characterized by comprising a metal conductor, an inner semi-conductive shielding layer, an insulating layer, an outer semi-conductive shielding layer and an outer sheath, wherein the inner semi-conductive shielding layer, the insulating layer, the outer semi-conductive shielding layer and the outer sheath are sequentially coated outside the metal conductor, and the insulating layer is formed by in-situ grafting, vulcanization, cross-linking and solidification of the compression-resistant insulating power cable material according to any one of claims 1-4 after extrusion.

Description

Compression-resistant insulating power cable material, preparation method and power cable Technical Field The invention relates to the technical field of power cable insulating materials, in particular to a compression-resistant insulating power cable material, a preparation method and a power cable. Background Crosslinked polyethylene is widely used in the insulation layer of power cables due to its good electrical insulation and processability. With the continuous improvement of the transmission capacity of the power grid, the heat productivity of the cable core in the operation process is increased, and higher requirements are put on the mechanical bearing capacity and creep resistance of the insulating material in a high-temperature environment. In order to improve the compression resistance of crosslinked polyethylene insulation, conventional processes typically add inorganic rigid particles as fillers to the polymer matrix. The inorganic particles and the nonpolar polymer matrix have obvious thermal expansion coefficient difference, and microscopic interface air gap defects are easily derived in the material in the cooling stage after the cable is crosslinked. These air gaps become centers of space charge accumulation and induce partial discharge, thereby reducing breakdown field strength of the insulating layer. When the cable is under the working condition of high temperature and heavy load, microscopic de-adhesion is easy to occur between the inorganic particles and the matrix resin, so that the filler loses the stress transmission capability, and finally creep deformation and mechanical failure of the insulating material are initiated. In a long-period high-temperature operating environment, the insulating material is also required to have stable thermal-oxidative aging resistance. The existing modification scheme adopts a mode of directly blending small molecular antioxidants to delay the aging of the materials. The traditional micromolecular antioxidant is easy to volatilize in the high-temperature crosslinking and long-term service stage, or is free in a polymer amorphous region and gradually migrates to the surface of the material to separate out, so that the long-term thermal oxygen stability of the insulating layer is reduced. The antioxidant with partial active groups such as mercapto and the like has higher free radical scavenging efficiency, but in the high-temperature crosslinking stage of the insulating material, the active protons can react with primary free radicals generated by the cleavage of the peroxide initiator in a chain termination way. The indiscriminate consumption interferes with the normal coupling process among polymer macromolecular chains, so that the crosslinking degree of the material is reduced, and the requirements of the high-temperature mechanical property and the processing crosslinking stability of the cable material are difficult to be met. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a compression-resistant insulating power cable material, a preparation method and a power cable, and solves the problems that when the high-temperature compression resistance of the existing power cable insulating material is improved, interface defects are easily caused by adding inorganic fillers, so that the electrical strength and creep resistance are reduced, and meanwhile, small-molecule antioxidants are easily migrated and separated out and interfere with the crosslinking curing process of the material. The compression-resistant insulated power cable material is prepared from the following raw materials, by weight, 70-90 parts of low-density polyethylene, 10-30 parts of ethylene propylene diene monomer rubber, 1.0-2.5 parts of N, N' -m-phenylene bismaleimide, 0.5-1.5 parts of 2-mercaptobenzimidazole, 0.5-1.5 parts of zinc stearate, 2.0-5.0 parts of zinc methacrylate and 1.0-2.0 parts of dicumyl peroxide. By adopting the technical scheme, the multi-dimensional structural node is built in the polymer homogeneous cross-linked network through in-situ chemical reaction among the formula components, so that the comprehensive effects of high-temperature compression resistance, electric field degradation inhibition and oxidation resistance are obtained. The in situ masking reaction anchors the macromolecular antioxidant structure. In the mixing processing stage of the insulating material, the maleimide groups at the two ends of the N, N' -m-phenylene bismaleimide have electron-deficient double bonds, and the 2-mercaptobenzimidazole contains electron-rich active mercapto functional groups. Under the action of heating and mechanical shearing, the sulfhydryl group and the maleimide double bond undergo Michael addition reaction. The addition reaction covalently bonds the benzimidazole ring with free radical scavenging activity to the rigid molecular skeleton of the m-phenylene bismaleimide to form a macromolecular antioxidant structural unit in