High-thermal-conductivity insulating electric power engineering material and preparation method thereof

Abstract

The invention discloses a high-thermal-conductivity insulating electric power engineering material and a preparation method thereof, and relates to the technical field of insulating material preparation. The composite material is prepared from 40-60 parts of polyimide resin, 20-30 parts of boron nitride nanosheets, 10-15 parts of alumina micro powder, 5-10 parts of a silane coupling agent, 3-8 parts of a plasticizer, 2-5 parts of an antioxidant, 1-3 parts of carbon nanotube whiskers, 1-2 parts of graphene quantum dots and 0.5-1 part of rare earth yttrium oxide. The diameter-thickness ratio of the boron nitride nanosheet is 100-200, the particle size of the alumina micro powder is 1-5 [mu] m, the diameter of the carbon nanotube whisker is 5-20 nm, the length is 1-5 [mu] m, and the particle size of the graphene quantum dot is 2-10 nm; all the raw materials are synergistically matched, so that the material is expected to have high thermal conductivity and excellent insulating property and is suitable for the field of electric power engineering. The material has high thermal conductivity and excellent insulativity, the thermal conductivity coefficient is not lower than 5 W / (m.K), the volume resistivity is not lower than 1015 omega.cm, and the breakdown field strength is not lower than 30 kV / mm.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating material preparation, and specifically to a highly thermally conductive insulating power engineering material and its preparation method. Background Art

[0002] In the field of power engineering, with the continuous development of power equipment towards high voltage, large capacity, and miniaturization, more stringent requirements are put forward for the performance of power engineering materials. As a key component in power engineering, the performance of highly thermally conductive insulating materials directly affects the operation stability, reliability, and service life of power equipment.

[0003] Traditional power engineering insulating materials, such as rubber, plastics, etc., although having certain insulating properties, have poor thermal conductivity. During the operation of power equipment, a large amount of heat is generated. If this heat cannot be dissipated in time, the equipment temperature will continue to rise. Excessive temperature will not only accelerate the aging and damage of the insulating material, reduce its insulating performance, but also may cause equipment failures or even safety accidents. For example, in a transformer, overheating of the insulating material may lead to insulation breakdown and cause a short circuit, seriously affecting the normal operation of the power system.

[0004] In order to improve the thermal conductivity of materials, some technologies adopt the method of adding highly thermally conductive fillers to the insulating matrix. However, common fillers such as alumina, magnesia, etc., although can improve the thermal conductivity of materials to a certain extent, the improvement amplitude is limited and it is difficult to meet the heat dissipation requirements of modern power equipment. Moreover, the interfacial thermal resistance between the filler and the matrix is large, affecting the heat transfer efficiency. In addition, excessive addition of fillers will also lead to problems such as a decrease in the mechanical properties of the material and an increase in processing difficulty.

[0005] In recent years, new highly thermally conductive fillers such as boron nitride and carbon nanotubes have gradually attracted attention. Boron nitride has a high thermal conductivity and good insulating properties, but in practical applications, the compatibility between boron nitride and the matrix material is poor, and agglomeration is likely to occur, thus affecting the comprehensive performance of the material. Although carbon nanotubes have excellent thermal conductivity, they are difficult to disperse and have certain limitations in insulating properties.

[0006] At the same time, existing power engineering materials also have deficiencies in arc resistance, tracking resistance, etc. In a high-voltage, high-electric-field environment, arc discharge and tracking phenomena are likely to occur on the material surface, which will not only damage the material surface, reduce the insulating performance, but also may cause more serious safety problems.

[0007] Therefore, the development of a power engineering material with high thermal conductivity, excellent insulation performance, good arc resistance and tracking resistance has become an urgent problem to be solved in the current power engineering field. A high thermal conductivity insulating power engineering material and its preparation method of the present invention aim to solve the problems existing in the above-mentioned prior art and provide a better material selection for the development of power engineering. Summary of the Invention

[0008] (1) Technical problems to be solved

[0009] In view of the deficiencies of the prior art, the present invention provides a high thermal conductivity insulating power engineering material and its preparation method.

[0010] (2) Technical solutions

[0011] A high thermal conductivity insulating power engineering material and its preparation method are made from raw materials in parts by mass: 40-60 parts of polyimide resin, 20-30 parts of boron nitride nanosheets, 10-15 parts of alumina micropowder, 5-10 parts of silane coupling agent, 3-8 parts of plasticizer, 2-5 parts of antioxidant, 1-3 parts of carbon nanotube whiskers, 1-2 parts of graphene quantum dots and 0.5-1 part of rare earth oxide; the aspect ratio of the boron nitride nanosheets is 100-200, the particle size of the alumina micropowder is 1-5 μm, the tube diameter of the carbon nanotube whiskers is 5-20 nm and the length is 1-5 μm, the particle size of the graphene quantum dots is 2-10 nm, and the rare earth oxide is yttrium oxide.

[0012] Furthermore, surface treatment of the boron nitride nanosheets is also included. First, plasma treatment technology is used to treat them for 5-10 min under the conditions of an argon atmosphere and a power of 100-200 W, and then a polydopamine layer with a thickness of 10-50 nm is coated on its surface with dopamine to enhance the interfacial bonding force with the polyimide resin.

[0013] Furthermore, the silane coupling agent is a compound prepared by mixing γ-aminopropyltriethoxysilane and γ-glycidyletheroxypropyltrimethoxysilane in a mass ratio of 2:1, the plasticizer is a compound prepared by mixing dioctyl phthalate and tributyl citrate in a mass ratio of 1:1, and the antioxidant is a compound prepared by mixing the hindered phenol antioxidant 1010 and the phosphite antioxidant 168 in a mass ratio of 1:1.

[0014] Further, first dry the boron nitride nanosheets, alumina micropowder, carbon nanotube whiskers and graphene quantum dots at 120 - 150 °C for 3 - 5 h; mix the dried materials with a silane coupling agent in a high-speed mixer at 1000 - 1500 r / min for 20 - 30 min, and simultaneously use ultrasonic assistance with an ultrasonic frequency of 20 - 40 kHz and a power of 100 - 300 W for surface modification; add the polyimide resin, modified filler, plasticizer, antioxidant and rare earth oxide into a twin-screw extruder and melt-blend and extrude into pellets at 300 - 350 °C.

[0015] Further, during the melt-blending process in the twin-screw extruder, a segmented temperature control technology is adopted, with the temperature in zone 1 being 300 - 310 °C, the temperature in zone 2 being 310 - 320 °C, the temperature in zone 3 being 320 - 330 °C, the temperature in zone 4 being 330 - 340 °C, and the temperature in zone 5 being 340 - 350 °C.

[0016] Further, the length-diameter ratio of the screw of the twin-screw extruder is 30 - 40:1, the screw speed is 150 - 250 r / min, and an axial magnetic field of 0.5 - 1 T is applied during the extrusion process to promote the oriented arrangement of the filler.

[0017] Further, it also includes hot-pressing the granulated materials. The hot-pressing temperature is 320 - 360 °C, the pressure is 10 - 20 MPa, the pressure-holding time is 10 - 20 min, and a pulse pressure application method is adopted during the hot-pressing process with a pulse frequency of 1 - 5 Hz.

[0018] Further, after hot-pressing and forming, post-treatment is carried out. First, anneal the material at 200 - 250 °C for 5 - 10 h, and then carry out low-temperature plasma treatment. Treat it for 8 - 15 min under the conditions of a nitrogen atmosphere and a power of 80 - 150 W to eliminate internal stress.

[0019] Further, the thermal conductivity of the material is not less than 5 W / (m·K), the volume resistivity is not less than 10 15 Ω·cm, the breakdown field strength is not less than 30 kV / mm, and it has arc resistance and tracking resistance.

[0020] Further, the material is applied to the fields of transformer insulation components, cable terminations, motor slot wedges, and high-voltage switch insulation parts in the power engineering field.

[0021] (III) Beneficial technical effects

[0022] Compared with the existing technology, the beneficial effects of the present invention are:

[0023] In terms of material composition, by compounding a variety of high - thermal - conductivity fillers such as boron nitride nanosheets, alumina micropowders, carbon nanotube whiskers, and graphene quantum dots, and adding rare - earth oxides, the thermal - conductivity performance of the material is greatly improved by utilizing the synergistic effect of each component. The thermal - conductivity coefficient of the material is not less than 5 W / (m·K), which can effectively dissipate the heat generated during the operation of electrical equipment, reduce the equipment temperature, and extend the service life of the equipment.

[0024] In the preparation process, special surface treatments are carried out on boron nitride nanosheets and carbon nanotube whiskers, enhancing the interfacial bonding force between the fillers and the polyimide resin matrix, reducing the interfacial thermal resistance, and improving the heat - transfer efficiency. At the same time, innovative steps such as ultrasonic - assisted surface modification, segmented temperature - controlled melt blending, axial magnetic - field extrusion, pulse - pressurized hot - pressing forming, and low - temperature plasma post - treatment are adopted to optimize the microstructure of the material, making the fillers uniformly dispersed and oriented, and further improving the comprehensive performance of the material. This material has excellent insulation performance, with a volume resistivity of not less than 10 15 Ω·cm and a breakdown field strength of not less than 30 kV / mm, which can effectively prevent current leakage and insulation breakdown, ensuring the safe operation of electrical equipment. In addition, the material also has good arc - resistance and tracking - resistance properties, and can maintain stable performance in high - voltage and high - electric - field environments.

[0025] This material can be widely applied to power - engineering fields such as transformer insulation components, cable terminations, motor slot wedges, and high - voltage switch insulation parts, significantly improving the heat - dissipation and insulation performance of electrical equipment, providing strong support for the development of high - voltage, large - capacity, and miniaturized electrical equipment, and having broad market application prospects and significant economic benefits. Brief Description of the Drawings

[0026] Figure 1 is a schematic diagram of a high - thermal - conductivity insulating power - engineering material and its preparation method. Detailed Embodiments

[0027] Refer to Figure 1 and the detailed embodiments of the present invention are as follows:

[0028] Example 1:

[0029] Raw material preparation: Weigh 40 parts of polyimide resin, 20 parts of boron nitride nanosheets (aspect ratio 100 - 200), 10 parts of alumina micropowder (particle size 1 - 5 μm), 1 part of carbon nanotube whiskers (tube diameter 5 - 20 nm, length 1 - 5 μm), 1 part of graphene quantum dots (particle size 2 - 10 nm), 0.5 part of yttrium oxide, 5 parts of silane coupling agent (compounded by γ-aminopropyltriethoxysilane and γ-glycidyletheroxypropyltrimethoxysilane in a mass ratio of 2:1), 3 parts of plasticizer (compounded by dioctyl phthalate and tributyl citrate in a mass ratio of 1:1), and 2 parts of antioxidant (compounded by hindered phenol antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1).

[0030] Filler treatment: Treatment of boron nitride nanosheets: Place the boron nitride nanosheets in a plasma treatment device and treat them for 10 min under an argon atmosphere with a power of 100 W. Then soak them in a dopamine solution and react at room temperature for 24 h to coat a poly(dopamine) layer with a thickness of about 10 nm on their surface.

[0031] Treatment of carbon nanotube whiskers: Carry out carboxylation treatment on the carbon nanotube whiskers to make the carboxyl content on their surface reach 3%.

[0032] Drying: Put the treated boron nitride nanosheets, alumina micropowder, carbon nanotube whiskers, and graphene quantum dots into an oven and dry them at 120 °C for 5 h.

[0033] Surface modification: Add the dried fillers and the silane coupling agent to a high-speed mixer and stir and mix them at a speed of 1000 r / min for 30 min. At the same time, turn on the ultrasonic assistance device with an ultrasonic frequency of 20 kHz and a power of 100 W.

[0034] Melt blending: Add the polyimide resin, modified fillers, plasticizer, antioxidant, and yttrium oxide to a twin-screw extruder. The length-diameter ratio of the twin-screw extruder is 30:1, and the screw rotation speed is 150 r / min. Adopt a segmented temperature control technology with the temperature of zone 1 being 300 °C, zone 2 being 310 °C, zone 3 being 320 °C, zone 4 being 330 °C, and zone 5 being 340 °C. Apply an axial magnetic field of 0.5 T during the extrusion process for melt blending and pelletizing.

[0035] Hot pressing and forming: Put the pelletized material into a mold and carry out hot pressing and forming by holding the pressure for 20 min at a hot pressing temperature of 320 °C and a pressure of 10 MPa. The hot pressing process adopts a pulsed pressure mode with a pulse frequency of 1 Hz.

[0036] Post-treatment: After hot pressing and forming, anneal the material at 200 °C for 10 h, and then put it into a low-temperature plasma treatment device and treat it for 15 min under a nitrogen atmosphere with a power of 80 W.

[0037] Example 2:

[0038] Raw material preparation: Weigh 50 parts of polyimide resin, 25 parts of boron nitride nanosheets, 12 parts of alumina micropowder, 2 parts of carbon nanotube whiskers, 1.5 parts of graphene quantum dots, 0.8 part of yttrium oxide, 7 parts of silane coupling agent, 5 parts of plasticizer, and 3 parts of antioxidant.

[0039] Filler treatment:

[0040] Treatment of boron nitride nanosheets: Plasma treatment for 7 min under an argon atmosphere with a power of 150 W, and then coat with a polydopamine layer with a thickness of about 30 nm.

[0041] Treatment of carbon nanotube whiskers: Carboxylation treatment to make the surface carboxyl content reach 5%.

[0042] Drying: Dry at 135 °C for 4 h.

[0043] Surface modification: Stir and mix at 1200 r / min for 25 min, with an ultrasonic frequency of 30 kHz and a power of 200 W.

[0044] Melt blending: The ratio of the screw length to the diameter of the twin-screw extruder is 35:1, and the screw speed is 200 r / min. The temperature of the first zone is 305 °C, the second zone is 315 °C, the third zone is 325 °C, the fourth zone is 335 °C, the fifth zone is 345 °C, and the axial magnetic field is 0.7 T.

[0045] Hot pressing: The hot pressing temperature is 340 °C, the pressure is 15 MPa, the pressure holding time is 15 min, and the pulse frequency is 3 Hz.

[0046] Post-treatment: Anneal at 225 °C for 7 h, and the power of the low-temperature plasma treatment is 120 W for 12 min.

[0047] Example 3:

[0048] Raw material preparation: Weigh 60 parts of polyimide resin, 30 parts of boron nitride nanosheets, 15 parts of alumina micropowder, 3 parts of carbon nanotube whiskers, 2 parts of graphene quantum dots, 1 part of yttrium oxide, 10 parts of silane coupling agent, 8 parts of plasticizer, and 5 parts of antioxidant.

[0049] Filler treatment: 1. Treatment of boron nitride nanosheets: Plasma treatment at 200 W for 5 min, and coat with a polydopamine layer of about 50 nm. 2. Treatment of carbon nanotube whiskers: Carboxylation to make the carboxyl content reach 8%. 3. Drying: Dry at 150 °C for 3 h.

[0050] Surface modification: Stir at 1500 r / min for 20 min, with an ultrasonic frequency of 40 kHz and a power of 300 W.

[0051] Melt blending: The length-diameter ratio of the screw is 40:1, and the screw speed is 250 r / min. The temperature of zone 1 is 310 °C, zone 2 is 320 °C, zone 3 is 330 °C, zone 4 is 340 °C, zone 5 is 350 °C, and the axial magnetic field is 1 T.

[0052] Hot pressing: The hot pressing temperature is 360 °C, the pressure is 20 MPa, the pressure holding time is 10 min, and the pulse frequency is 5 Hz.

[0053] Post-treatment: Annealing at 250 °C for 5 h, and the power of low-temperature plasma treatment is 150 W, and the treatment time is 8 min.

[0054] Comparative example:

[0055] Raw material preparation: Weigh 50 parts of polyimide resin, 25 parts of ordinary boron nitride powder, 12 parts of alumina fine powder, 5 parts of γ-aminopropyltriethoxysilane, 5 parts of dioctyl phthalate, and 3 parts of hindered phenol antioxidant 1010.

[0056] Mixing and granulation: The raw materials are directly added to a twin-screw extruder without surface treatment of the filler and special process operations, and melt blending and extrusion granulation are carried out at 320 °C.

[0057] Hot pressing: The granulated material is hot pressed at 340 °C and 15 MPa for 15 min.

[0058] Performance testing:

[0059] The materials prepared in Examples 1-3 and the comparative example were subjected to performance testing, and the results are as follows:

[0060]

[0061] It can be seen from the test results that the high thermal conductivity and insulating power engineering materials prepared in the examples are significantly superior to the comparative example in terms of thermal conductivity, insulation performance, arc resistance, and tracking resistance, etc., proving that the material formula and preparation process of the present invention have significant advantages.

[0062] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high thermal conductivity insulating power engineering material and a preparation method thereof, characterized in that: The invention is prepared from the following raw materials in parts by weight: 40-60 parts of polyimide resin, 20-30 parts of boron nitride nanosheets, 10-15 parts of aluminum oxide powder, 5-10 parts of silane coupling agent, 3-8 parts of plasticizer, 2-5 parts of antioxidant, 1-3 parts of carbon nanotube whiskers, 1-2 parts of graphene quantum dots and 0.5-1 parts of rare earth oxide; the diameter-to-thickness ratio of the boron nitride nanosheets is 100-200, the particle size of the aluminum oxide powder is 1-5 μm, the diameter of the carbon nanotube whiskers is 5-20 nm and the length is 1-5 μm, the particle size of the graphene quantum dots is 2-10 nm, and the rare earth oxide is yttrium oxide.

2. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 1, characterized in that: The method also includes surface treatment of boron nitride nanosheets, first using plasma treatment technology, treating for 5-10 minutes in an argon atmosphere at a power of 100-200W, and then using dopamine to coat the surface with a polydopamine layer with a thickness of 10-50nm to enhance the interface bonding force with the polyimide resin.

3. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 1, characterized in that: The silane coupling agent is a compound of γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a mass ratio of 2:1, the plasticizer is a compound of dioctyl phthalate and tributyl citrate in a mass ratio of 1:1, and the antioxidant is a compound of hindered phenol antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:

1.

4. A method for preparing the high thermal conductivity insulating power engineering material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. First, dry the boron nitride nanosheets, alumina powder, carbon nanotube whiskers and graphene quantum dots at 120-150° C. for 3-5 h; S2, mixing the dried material with the silane coupling agent in a high-speed mixer at 1000-1500 r / min for 20-30 min, and simultaneously using ultrasound assistance with an ultrasound frequency of 20-40 kHz and a power of 100-300 W for surface modification; S3, adding polyimide resin, modified filler, plasticizer, antioxidant and rare earth oxide into a twin-screw extruder, and melt-blending and extruding to granulate at 300-350°C.

5. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 4, characterized in that: During the melt blending process of the twin-screw extruder, the segmented temperature control technology is adopted, the temperature of zone one is 300-310℃, the temperature of zone two is 310-320℃, the temperature of zone three is 320-330℃, the temperature of zone four is 330-340℃, and the temperature of zone five is 340-350℃.

6. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 4, characterized in that: The screw length-diameter ratio of the twin-screw extruder is 30-40:1, the screw speed is 150-250 r / min, and an axial magnetic field of 0.5-1 T is applied during the extrusion process.

7. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 4, characterized in that: The method also includes hot pressing the granulated material, the hot pressing temperature is 320-360°C, the pressure is 10-20MPa, the holding time is 10-20min, and a pulse pressurization method is adopted during the hot pressing process, and the pulse frequency is 1-5Hz.

8. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 7, characterized in that: After hot pressing, the material is post-processed by annealing at 200-250°C for 5-10 hours, and then treated with low-temperature plasma for 8-15 minutes in a nitrogen atmosphere at a power of 80-150W to eliminate internal stress.

9. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 1, characterized in that: The thermal conductivity of the material is not less than 5W / (m·K), and the volume resistivity is not less than 10 15 Ω·cm, the breakdown field strength is not less than 30kV / mm, and it has arc resistance and tracking resistance.

10. A high thermal conductivity insulating power engineering material and a preparation method thereof according to claim 1, characterized in that: The material is used in transformer insulation parts, cable terminal heads, motor slot wedges, high-voltage switch insulation parts and power engineering fields.

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