An insulating epoxy material, its preparation method and application

Abstract

This invention discloses an insulating epoxy material, its preparation method, and its applications. The raw materials for preparing the above-mentioned insulating epoxy material include 100 parts of solid bisphenol A type epoxy resin, 30-50 parts of an anhydride curing agent, and 200-320 parts of silica powder. By selecting specific bisphenol A epoxy resins and combining them with other components, excellent electrical properties, mechanical properties, durability, and flame retardancy are obtained, better meeting the requirements of GIS terminal products. This invention also provides a preparation method and applications of the above-mentioned insulating epoxy material.

Description

Technical Field

[0001] This invention relates to the field of epoxy materials technology, and in particular to an insulating epoxy material, its preparation method, and its application. Background Technology

[0002] Currently, insulating epoxy materials can be used in power products such as dry-type transformers, dry-type instrument transformers, insulated switches, disc insulators, and support insulators. These materials typically have high requirements for certain performance aspects. For example, dry-type transformers and dry-type instrument transformers require materials with high glass transition temperatures and low coefficients of linear expansion, but relatively low requirements for electrical performance and virtually no requirements for toughness. Insulated switches mainly have high requirements for the electrical performance of the materials, with low requirements for physical and mechanical properties. Disc insulators and support insulators need to withstand high air pressure, so they have high requirements for the compressive strength of the materials, but low requirements for electrical performance.

[0003] GIS (Gas Insulated Switchgear) terminal products play a crucial role in power systems to ensure their normal operation. Relevant performance requirements include: (1) High insulation performance, requiring high electrical performance to effectively isolate high-voltage circuits from the ground and prevent faults such as arcing and leakage; (2) High withstand performance, requiring the ability to withstand high voltage and high current surges and withstand high-energy fault currents in a short time to ensure stable system operation; (3) High sealing performance, requiring good sealing performance to effectively prevent gas leakage and ensure stable system operation; (4) Harsh environmental adaptability, requiring the ability to adapt to various harsh environmental conditions, including high temperature, extreme cold, and high altitude environments, and requiring high mechanical properties of materials; (5) High safety performance, effectively preventing accidents such as arcing and fires to ensure the safety of personnel and equipment. Therefore, GIS terminal products have high comprehensive performance requirements for insulation materials, such as excellent electrical and mechanical properties, high and low temperature environmental tolerance, and reliable flame retardancy. Currently, epoxy resin is the main insulating material used in GIS terminal products. However, existing epoxy materials cannot simultaneously meet the aforementioned performance requirements, making it difficult for GIS terminal products to meet the requirements of high-voltage conditions and limiting their application.

[0004] Therefore, developing an insulating epoxy material with better overall performance to better meet the usage requirements of electrical components (such as GIS terminal products) is a problem that needs to be solved at present. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an insulating epoxy material that combines advantages in electrical properties, mechanical properties, durability, and flame retardancy.

[0006] The present invention also proposes a method for preparing the above-mentioned insulating epoxy material.

[0007] The present invention also proposes the application of the above-mentioned insulating epoxy material.

[0008] The first aspect of this invention relates to an insulating epoxy material, comprising the following raw materials by weight: 100 parts epoxy resin, 30-50 parts acid anhydride curing agent, and 200-320 parts silica powder; wherein the epoxy resin is a solid bisphenol A type epoxy resin with an epoxy value of 2.4-2.65 Eq / kg and a viscosity of 370-550 mPa·s at 120°C.

[0009] The insulating epoxy material according to the first aspect of the present invention has at least the following beneficial effects:

[0010] By selecting specific bisphenol A epoxy resins and combining them with other components, excellent electrical, mechanical, durability, and flame retardant properties are achieved. A certain epoxy value ensures appropriate crosslinking density and reactivity, guaranteeing uniform curing and improving strength and toughness. If the epoxy value is too low, the overall crosslinking degree is insufficient, which is detrimental to strength improvement and results in poor heat resistance; if the epoxy value is too high, the curing crosslinking degree is too high, which easily leads to microscopic defects and stress within the material, making it brittle and hindering toughness improvement and application in low-temperature environments. At the same epoxy value, if a liquid epoxy resin is selected, its lower molecular weight results in excessively high crosslinking.

[0011] Bisphenol A type epoxy resin has excellent mechanical properties and electrical insulation properties, and the raw materials are readily available and the cost is low. Other types of epoxy resins, such as bisphenol F type epoxy resin, are not only more expensive, but also have poor heat resistance and toughness.

[0012] Using anhydride-based curing agents results in low curing shrinkage, which improves the dimensional stability of the product, reduces molding internal stress, and further enhances the material's mechanical properties, tolerance to high and low temperature environments, and electrical properties.

[0013] Compared to conventional flame-retardant fillers such as aluminum hydroxide, magnesium hydroxide, and brominated flame retardants, silica powder, as a filler, exhibits high thermal stability and heat resistance. Its low coefficient of thermal expansion prevents decomposition at high temperatures, thus improving the overall thermal and dimensional stability of epoxy resins. Silica powder effectively reinforces and toughens epoxy resins, enhancing strength, rigidity, and toughness. Furthermore, its excellent electrical insulation properties enhance electrical insulation performance and reduce dielectric loss. As an environmentally friendly filler, silica powder is low-cost, halogen-free, and does not release toxic or harmful gases during combustion. Therefore, using silica powder as a flame-retardant filler in epoxy resins is beneficial for improving thermal stability, mechanical properties, and electrical insulation performance, while offering environmental and cost advantages.

[0014] According to some embodiments of the present invention, the anhydride curing agent is 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, or any value between them.

[0015] According to some embodiments of the present invention, the anhydride curing agent includes at least one of a first methyltetrahydrophthalic anhydride and a composition of second methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol, wherein the mass fraction of 2,4,6-tris(dimethylaminomethyl)phenol in the composition is 0.1% to 3%. The above curing system has a fast curing rate, which is beneficial for obtaining high-performance insulating epoxy materials.

[0016] For the compound system of methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol, adding a small amount of 2,4,6-tris(dimethylaminomethyl)phenol can promote the ring-opening of epoxy groups, making it easier for epoxy molecules to react with methyltetrahydrophthalic anhydride and accelerating the curing rate of epoxy resin.

[0017] According to some embodiments of the present invention, the mass fraction of 2,4,6-tris(dimethylaminomethyl)phenol in the composition is 0.1%, 0.5%, 1%, 2%, 3%, or any value between them.

[0018] According to some embodiments of the present invention, the anhydride curing agent is selected from the first methyltetrahydrophthalic anhydride, or a composition of the second methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol; and optionally, the anhydride curing agent is 30 to 45 parts, specifically 30 parts, 35 parts, 40 parts, 45 parts or any value between them.

[0019] According to some embodiments of the present invention, the anhydride curing agent is selected from the first methyltetrahydrophthalic anhydride and the second methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol.

[0020] According to some embodiments of the present invention, the first methyltetrahydrophthalic anhydride is 20 to 30 parts, for example, specifically 20 parts, 25 parts, 28 parts, 30 parts or any value therebetween; the composition of the second methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol is 10 to 20 parts, for example, specifically 10 parts, 14 parts, 18 parts, 20 parts or any value therebetween.

[0021] According to some embodiments of the present invention, in the first methyltetrahydrophthalic anhydride and / or the second methyltetrahydrophthalic anhydride, the mass fraction of the anhydride is ≥40%, and the acid value is ≥660 mg KOH / g. The theoretical mass fraction of the anhydride in the methyltetrahydrophthalic anhydride is approximately 43.37%, and the theoretical acid value is approximately 692 mg KOH / g. Therefore, the mass fraction and acid value of the above-mentioned anhydride are close to the theoretical values, indicating high purity and low impurity content, which is beneficial for improving electrical performance.

[0022] According to some embodiments of the present invention, the average particle size of the silicon micropowder is 25 to 40 μm, specifically 25 μm, 30 μm, 35 μm, 40 μm or any value between them.

[0023] According to some embodiments of the present invention, the purity of the silicon micropowder is 99.5% or higher by mass fraction. Using high-purity silicon micropowder reduces impurity content and improves electrical performance.

[0024] According to some embodiments of the present invention, the content of the silicon micropowder is 200 parts, 250 parts, 300 parts, 320 parts or any value between them.

[0025] According to some embodiments of the present invention, the raw materials for preparing the insulating epoxy material also include color powder. The color powder is used for coloring. The present invention does not have special requirements on the type and amount of color powder, and suitable color powder and its amount can be easily selected according to the coloring requirements. For example, the color powder is selected from iron oxide red, and the amount used is, for example, 1-2 parts / 100 parts epoxy resin, with a particle size of, for example, 20-30 μm. It should be understood that, in addition to iron oxide red, chrome yellow, chrome green, titanium dioxide, and other color powders can also be selected according to different colors. The amount and particle size of the color powder are usually selected according to the coloring depth, the hiding power of the color powder, etc. Based on the mass of the epoxy resin, the reference amount of color powder is 0.1% to 5%.

[0026] The second aspect of the present invention relates to a method for preparing the above-mentioned insulating epoxy material, comprising: mixing raw materials including the epoxy resin and the silicon micro powder in a first mixing at a temperature where the epoxy resin is in a liquid state to obtain a first mixture; adding the acid anhydride curing agent to the first mixture and mixing in a second mixing to obtain a second mixture; and casting the second mixture into a mold to obtain the insulating epoxy material.

[0027] The method for preparing the insulating epoxy material according to the second aspect of the present invention has at least the following beneficial effects:

[0028] First, all components except for the anhydride curing agent are mixed to prevent premature reaction of the curing agent, which would increase the material viscosity and affect the casting rate. This method is simple and can produce insulating epoxy materials with excellent electrical, mechanical, durability, and flame retardancy properties.

[0029] According to some embodiments of the present invention, the insulating epoxy material includes color powder, and the preparation method of the first mixture includes: mixing the preparation raw materials including the epoxy resin, the silicon micro powder, and the color powder for the first time at a temperature when the epoxy resin is in a liquid state to obtain the first mixture.

[0030] According to some embodiments of the present invention, the heating temperature is 125-130°C.

[0031] According to some embodiments of the present invention, the temperature of the first mixing is 125-130°C.

[0032] According to some embodiments of the present invention, the temperature of the first mixture is 125-130°C before the anhydride curing agent is added to the first mixture.

[0033] According to some embodiments of the present invention, the anhydride curing agent is preheated before being added to the first mixture to reduce the temperature difference caused by the addition of the curing agent, so that it can be quickly cast after mixing, thereby improving production efficiency, reducing the heating time of the curing agent, reducing the volatilization of the curing agent, and avoiding the impact on the overall performance of the material due to uneven preheating.

[0034] In practical applications, the temperatures of the first mixture and the anhydride curing agent before the second mixing are appropriately controlled according to the curing temperature of the subsequent casting, so that the temperature of the two mixtures after mixing is close to the curing temperature, allowing for direct casting after mixing. Furthermore, to reduce curing agent volatilization, the preheating temperature of the anhydride curing agent is kept as low as possible.

[0035] According to some embodiments of the present invention, the curing agent is preheated to a temperature of 40–60°C.

[0036] According to some embodiments of the present invention, the first mixing and / or the second mixing includes stirring. The first mixing and / or the second mixing may be carried out at a relatively gentle stirring rate (i.e., the stirring rate does not need to be too high), mainly to create agitation, avoid packing material settling, and facilitate material mixing.

[0037] According to some embodiments of the present invention, a first vacuum degassing process is performed after the first mixing.

[0038] According to some embodiments of the present invention, the vacuum degree of the first vacuum degassing process is not greater than 50 Pa.

[0039] According to some embodiments of the present invention, the time for the first vacuum degassing process is 60 to 90 minutes.

[0040] According to some embodiments of the present invention, stirring is carried out during the first vacuum degassing process. A relatively gentle stirring rate can be selected to create agitation, which facilitates the removal of bubbles.

[0041] According to some embodiments of the present invention, a second vacuum degassing process is performed after the second mixing.

[0042] According to some embodiments of the present invention, the vacuum degree of the second vacuum degassing process is not greater than 100 Pa.

[0043] According to some embodiments of the present invention, the second vacuum degassing process takes 10 to 15 minutes.

[0044] According to some embodiments of the present invention, stirring is carried out during the second vacuum degassing process. A relatively gentle stirring rate can be selected, mainly to ensure that the materials are mixed evenly.

[0045] According to some embodiments of the present invention, the curing process for the casting molding is as follows: curing at 110–120°C for 3–9 hours, curing at 138–142°C for 4–6 hours, and curing at 128–132°C for 11–12 hours. These process parameters not only ensure a suitable degree of crosslinking but also help reduce molding shrinkage, further improving the overall performance of the insulating epoxy material.

[0046] According to some embodiments of the present invention, the casting process is followed by uniform cooling to reduce the generation of internal stress.

[0047] According to some embodiments of the present invention, the constant cooling rate is 0.1 to 0.5 °C / min.

[0048] The third aspect of the present invention relates to the application of the above-mentioned insulating epoxy material in GIS terminal products.

[0049] Given the advantages of the aforementioned insulating epoxy materials in terms of electrical properties, mechanical properties, durability, and flame retardancy, they can better meet the usage requirements of GIS terminal products and can be used in the production of high-voltage GIS terminal products.

[0050] According to some embodiments of the present invention, the operating voltage of the GIS terminal product is 110-330kV.

[0051] In this article, the numerical ranges mentioned include the endpoints and any subsets within that range; "above" includes the number itself, for example, "above 2" includes 2.

[0052] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0053] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0054] The raw materials used in the following examples and comparative examples are described below:

[0055] Epoxy Resin A: Bisphenol A type epoxy resin, epoxy value 2.44~2.63Eq / kg, viscosity (120℃) 370~550mPa·s.

[0056] Epoxy Resin B: Bisphenol A type epoxy resin, epoxy value 0.48~0.54Eq / kg, viscosity at 25℃ is 3000~8000mPa·s.

[0057] Epoxy Resin C: Bisphenol A type epoxy resin, epoxy value 5.1~5.5Eq / kg, viscosity at 25℃ is 10000~15000mPa·s.

[0058] Curing agent A: Methyltetrahydrophthalic anhydride, acid value 660-685 mgKOH / g, viscosity not greater than 50 mPa·s, anhydride mass content greater than 40%.

[0059] Curing agent B: a mixture of 2,4,6-tris(dimethylaminomethyl)phenol and methyltetrahydrophthalic anhydride, wherein the mass fraction of 2,4,6-tris(dimethylaminomethyl)phenol is 1%, and the parameters of methyltetrahydrophthalic anhydride are the same as those of curing agent A.

[0060] Filler: Silica powder with an average particle size of 30μm and a purity of over 99.5%.

[0061] Pigment: Iron oxide red, with an average particle size of 30 μm.

[0062] Unless otherwise specified, all raw materials or equipment mentioned are commercially available and readily available.

[0063] Example 1

[0064] This embodiment prepares an insulating epoxy material, which, by mass parts, includes the following raw materials: 100 parts epoxy resin A, 42 parts curing agent (curing agent A), 250 parts filler, and 1 part color powder.

[0065] The preparation steps of this insulating epoxy material are as follows:

[0066] 1) Mix epoxy resin A, filler and color powder in proportion at 130℃ and stir for 15-20 minutes to make the materials uniform. During this process, the temperature is controlled between 125-130℃.

[0067] 2) Maintain constant temperature and perform vacuum degassing treatment on the mixture while stirring. The vacuum degree should not exceed 50 Pa, and the treatment time should be 60 to 90 minutes until no obvious bubbles appear on the surface of the mixture.

[0068] 3) Weigh out the curing agent at about 60℃ (hold at 60℃ for more than 30 minutes) according to the proportion and add it to the above constant temperature mixture. Stir and evacuate the vacuum for 10 to 15 minutes, with the vacuum degree not exceeding 100 Pa.

[0069] 4) Pour the degassed composition into a preheated experimental mold and cure it in three stages in a forced-air heating oven at 115±3℃ / 9h, 140±2℃ / 6h, and 130±2℃ / 12h.

[0070] 5) Cool to room temperature in a forced-air drying oven at a cooling rate of 0.3℃ / min.

[0071] Example 2

[0072] This embodiment prepares an insulating epoxy material, which, by mass parts, includes the following raw materials: 100 parts epoxy resin A, 42 parts curing agent (28 parts curing agent A, mass percentage of 66.7%; 14 parts curing agent B, mass percentage of 33.3%), 250 parts filler, and 1 part color powder.

[0073] The preparation steps of this insulating epoxy material are as follows:

[0074] 1) Mix epoxy resin A, filler and color powder in proportion at 130℃ and stir for 15-20 minutes to make the materials uniform. During this process, the temperature is controlled between 125-130℃.

[0075] 2) Maintain constant temperature and perform vacuum degassing treatment on the mixture while stirring. The vacuum degree should not exceed 50 Pa, and the treatment time should be 60 to 90 minutes until no obvious bubbles appear on the surface of the mixture.

[0076] 3) Weigh out the curing agent at about 60℃ (keep the temperature at 60℃ for more than 30 minutes) according to the proportion and add it to the above constant temperature mixture. Stir and evacuate the vacuum for 10 to 15 minutes, with the vacuum degree not exceeding 100 Pa.

[0077] 4) Pour the degassed composition into a preheated experimental mold and cure it in three stages in a forced-air heating oven at 115±3℃ / 5h, 140±2℃ / 5h, and 130±2℃ / 12h.

[0078] 5) Cool to room temperature in a forced-air drying oven at a cooling rate of 0.3℃ / min.

[0079] Example 3

[0080] This embodiment prepares an insulating epoxy material, which, by mass parts, includes the following raw materials: 100 parts epoxy resin A, 42 parts curing agent (curing agent B), 250 parts filler, and 1 part color powder.

[0081] The preparation steps of this insulating epoxy material are as follows:

[0082] 1) Mix epoxy resin A, filler and color powder in proportion at 130℃ and stir for 15-20 minutes to make the materials uniform. During this process, the temperature is controlled between 125-130℃.

[0083] 2) Maintain constant temperature and perform vacuum degassing treatment on the mixture while stirring. The vacuum degree should not exceed 50 Pa, and the treatment time should be 60 to 90 minutes until no obvious bubbles appear on the surface of the mixture.

[0084] 3) Weigh out the curing agent at about 60℃ (keep the temperature at 60℃ for more than 30 minutes) according to the proportion and add it to the above constant temperature mixture. Stir and evacuate the vacuum for 10 to 15 minutes, with the vacuum degree not exceeding 100 Pa.

[0085] 4) Pour the degassed composition into a preheated experimental mold and cure it in three stages in a forced-air heating oven at 115±3℃ / 3h, 140±2℃ / 4h, and 130±2℃ / 12h.

[0086] 5) Cool to room temperature in a forced-air drying oven at a cooling rate of 0.3℃ / min.

[0087] Comparative Example 1

[0088] This comparative example prepared an insulating epoxy material, which, by mass parts, includes the following raw materials: 100 parts epoxy resin B, 42 parts curing agent (curing agent A), 250 parts filler, and 1 part color powder.

[0089] The preparation steps of this insulating epoxy material are as follows:

[0090] 1) Mix epoxy resin B, filler and color powder in proportion at 130℃ and stir for 15-20 minutes to make the materials evenly mixed. During this process, the temperature is controlled between 125-130℃.

[0091] 2) Maintain constant temperature and perform vacuum degassing treatment on the mixture while stirring. The vacuum degree should not exceed 50 Pa and the treatment time should be 60 to 90 minutes until no obvious bubbles appear on the surface of the mixture.

[0092] 3) Weigh out the curing agent at about 60℃ (keep the temperature at 60℃ for more than 30 minutes) according to the proportion and add it to the above constant temperature mixture. Stir and evacuate the vacuum for 10 to 15 minutes, with the vacuum degree not exceeding 100 Pa.

[0093] 4) Pour the degassed epoxy material into a preheated experimental mold and cure it in three stages in a forced-air heating oven at 115±3℃ / 9h, 140±2℃ / 6h, and 130±2℃ / 12h.

[0094] 5) Cool to room temperature in a forced-air drying oven at a cooling rate of 0.3℃ / min.

[0095] Comparative Example 2

[0096] This comparative example prepared an insulating epoxy material, which, by mass parts, includes the following raw materials: 100 parts epoxy resin C, 42 parts curing agent (curing agent A), 250 parts filler, and 1 part color powder.

[0097] The preparation steps of this insulating epoxy material are as follows:

[0098] 1) Mix epoxy resin C, filler and color powder in proportion at 130℃ and stir for 15-20 minutes to make the materials uniform. During this process, the temperature is controlled between 125-130℃.

[0099] 2) Maintain constant temperature and perform vacuum degassing treatment on the mixture while stirring. The vacuum degree should not exceed 50 Pa, and the treatment time should be 60 to 90 minutes until no obvious bubbles appear on the surface of the mixture.

[0100] 3) Weigh out the curing agent at about 60℃ (keep the temperature at 60℃ for more than 30 minutes) according to the proportion and add it to the above constant temperature mixture. Stir and evacuate the vacuum for 10 to 15 minutes, with the vacuum degree not exceeding 100 Pa.

[0101] 4) Pour the degassed epoxy material into a preheated experimental mold and cure it in three stages in a forced-air heating oven at 115±3℃ / 9h, 140±2℃ / 6h, and 130±2℃ / 12h.

[0102] 5) Cool to room temperature in a forced-air drying oven at a cooling rate of 0.3℃ / min.

[0103] Test case

[0104] I. Electrical Performance

[0105] Experimental Groups: Five experimental groups were set up, namely Experimental Groups 1 to 5. The insulating epoxy materials prepared in Experimental Groups 1 to 3 and Comparative Examples 1 to 2 were used to make samples. Each group had 5 samples, for a total of 25 samples. All samples had the same size and appearance.

[0106] Experimental methods: At room temperature, the breakdown strength was tested according to GB / T 1408-2006, the dielectric constant and dielectric loss tangent were tested according to GB / T1409-2006, and the volume resistivity was tested according to GB / T1410-2006.

[0107] II. Low Temperature Resistance Test

[0108] Experimental Groups: Five experimental groups were set up, namely Experimental Groups 1 to 5. Experimental Groups 1 to 5 used insulating epoxy materials prepared in Examples 1 to 3 and Comparative Examples 1 to 2 to make test samples. The test sample diameter was 150 mm, with a square metal insert with a side length of 70 mm in the center. The four corners of the insert were rounded with R2 to R10, that is, the aforementioned insulating epoxy material was poured around the metal insert. Each group had 5 test samples, for a total of 25 test samples. All test samples were the same in size and appearance.

[0109] Experimental method: Take the samples from experimental groups 1 to 5 and put them into a freezing chamber. Set the temperature to -60℃ and the time to 72h, and observe whether the samples crack.

[0110] III. High and Low Temperature Cycling Experiment

[0111] Experimental Groups: Five experimental groups were set up, namely Experimental Groups 1 to 5. The insulating epoxy materials prepared in Experimental Groups 1 to 3 and Comparative Examples 1 to 2 were used to prepare the test samples. The shape and size of the test samples were the same as in the "Low Temperature Resistance Test". Each group had 5 test samples, for a total of 25 test samples. All test samples were the same in size and appearance.

[0112] Experimental method: Take the samples from experimental groups 1 to 5 and put them into a hot and cold cycle chamber. The cycle temperature range is -60 to 100℃. Cycle for 10 cycles at a heating and cooling rate of 0.5℃ / min. Observe whether the samples crack.

[0113] IV. Mechanical Properties

[0114] Experimental Groups: Five experimental groups were set up, namely Experimental Groups 1 to 5. The insulating epoxy materials prepared in Experimental Groups 1 to 3 and Comparative Examples 1 to 2 were used to make samples. Each group had 5 samples, for a total of 25 samples. All samples had the same size and appearance.

[0115] Experimental methods: Impact strength, flexural strength and compressive strength were tested at room temperature according to GB / T 2567-2021.

[0116] V. Flame retardant properties

[0117] Experimental Groups: Five experimental groups were set up, namely Experimental Groups 1 to 5. The insulating epoxy materials prepared in Experimental Groups 1 to 3 and Comparative Examples 1 to 2 were used to make samples. Each group had 5 samples, for a total of 25 samples. All samples had the same size and appearance.

[0118] Experimental method: The flame retardancy rating was evaluated according to GB / T 2408-2008 at room temperature.

[0119] VI. Glass transition temperature (Tg)

[0120] Experimental Groups: Five experimental groups were set up, namely Experimental Groups 1 to 5. The insulating epoxy materials prepared in Experimental Groups 1 to 5 were used to make samples. Each group had 3 samples, for a total of 15 samples. All samples were the same in size and appearance.

[0121] Experimental method: Tg was measured at room temperature according to GB / T 19466-2004.

[0122] VII. Heat distortion temperature

[0123] Experimental Groups: Five experimental groups were set up, namely Experimental Groups 1 to 5. The insulating epoxy materials prepared in Experimental Groups 1 to 3 and Comparative Examples 1 to 2 were used to make samples. Each group had 5 samples, for a total of 25 samples. All samples had the same size and appearance.

[0124] Experimental method: The heat distortion temperature was determined according to GB / T 1634-2004 at room temperature.

[0125] The test results of Examples 1-3 are shown in Table 1.

[0126] Table 1. Performance comparison of insulating epoxy materials in Examples 1-3

[0127]

[0128] The following are some properties of the insulating epoxy material in Comparative Example 1:

[0129] Breakdown strength: 25.0kV / mm@1mm, Low temperature resistance (-60℃ / 72h): cracking, High and low temperature resistance (-60~100℃): cracking in 3 cycles, Flexural strength: 113.0MPa, Compressive strength: 122.0MPa.

[0130] The following are some properties of the insulating epoxy material in Comparative Example 2:

[0131] Low temperature resistance (-60℃ / 72h): cracking; High and low temperature resistance (-60~100℃): cracking in 2 cycles; Impact strength: 9.52kJ / m. 2 .

[0132] As can be seen from the experimental results in Table 1, the insulating epoxy materials of Examples 1-3 all exhibit excellent electrical properties, mechanical properties, high and low temperature environmental durability, and flame retardant properties, and can be used in the production of GIS terminal products for 110-330kV cable accessories. Examples 2 and 3 show that adding curing agent B (a mixture of 2,4,6-tris(dimethylaminomethyl)phenol and methyltetrahydrophthalic anhydride) can yield high-performance epoxy resin materials at a faster curing rate.

[0133] Epoxy resin B in Comparative Example 1 has a low epoxy value and low crosslinking degree. Its electrical properties, mechanical strength, low-temperature resistance, and high- and low-temperature environmental durability are all inferior to those of Examples 1-3. The insufficient low-temperature resistance and high- and low-temperature environmental durability may be related to the excessively low mechanical strength. Epoxy resin C in Comparative Example 2 has a high epoxy value and a lower molecular weight than epoxy resin A in the examples. After curing, the material has a very high degree of internal crosslinking. High crosslinking reduces molecular chain movement, resulting in lower toughness, low-temperature resistance, and high- and low-temperature resistance.

[0134] In summary, the epoxy materials in Comparative Examples 1 and 2 cannot meet the usage requirements of GIS terminal products for 110-330kV cable accessories, and can only be used for cable accessory products with lower voltage levels. However, the insulating epoxy material in this embodiment has superior performance and can better meet the application requirements of high-voltage (110-330kV) GIS terminal products, and can be used in the production of high-voltage GIS terminal products.

[0135] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An insulating epoxy material, characterized in that, The following raw materials are included in the preparation by weight: 100 parts epoxy resin, 30-45 parts acid anhydride curing agent, 200-320 parts silica powder; The epoxy resin is a solid bisphenol A type epoxy resin with an epoxy value of 2.44~2.63 Eq / kg and a viscosity of 370~550 mPa·s at 120℃. The anhydride curing agent includes at least one of methyltetrahydrophthalic anhydride and a composition of methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol, wherein the mass fraction of 2,4,6-tris(dimethylaminomethyl)phenol in the composition is 0.1% to 3%; The average particle size of the silicon micropowder is 25~40μm.

2. The insulating epoxy material according to claim 1, characterized in that, The anhydride curing agent is selected from the first methyltetrahydrophthalic anhydride, or a combination of the second methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol.

3. The insulating epoxy material according to claim 1, characterized in that, The anhydride curing agent is the first methyltetrahydrophthalic anhydride, and a combination of the second methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol.

4. The insulating epoxy material according to claim 3, characterized in that, The first methyltetrahydrophthalic anhydride is 20-30 parts, and the composition of the second methyltetrahydrophthalic anhydride and 2,4,6-tris(dimethylaminomethyl)phenol is 10-20 parts.

5. The insulating epoxy material according to claim 1, characterized in that, In the first methyltetrahydrophthalic anhydride and / or the second methyltetrahydrophthalic anhydride, the mass fraction of the anhydride is ≥40% and the acid value is ≥660mgKOH / g.

6. The insulating epoxy material according to claim 1, characterized in that, The silicon micropowder has a purity of 99.5% or higher; and / or, the raw materials for preparing the insulating epoxy material also include color powder.

7. The method for preparing the insulating epoxy material according to any one of claims 1-6, characterized in that, include: The preparation raw materials, including the epoxy resin and the silicon micro powder, are mixed for the first time at a temperature when the epoxy resin is in a liquid state to obtain a first mixture; The anhydride curing agent is added to the first mixture, and then mixed a second time to obtain the second mixture; The second mixture is cast into a mold to obtain the insulating epoxy material.

8. The method for preparing the insulating epoxy material according to claim 7, characterized in that, The heating temperature is 125~130℃; and / or, the temperature of the first mixing is 125~130℃; and / or, the temperature of the first mixture is 125~130℃ before adding the anhydride curing agent to the first mixture; and / or, the anhydride curing agent is preheated before adding the anhydride curing agent to the first mixture; and / or, a first vacuum degassing treatment is performed after the first mixing; and / or, a second vacuum degassing treatment is performed after the second mixing.

9. The method for preparing the insulating epoxy material according to claim 7, characterized in that, The curing process of the casting is as follows: curing at 110~120℃ for 3~9h, curing at 138~142℃ for 4~6h, and curing at 128~132℃ for 11~12h; and / or, uniform cooling is performed after casting.

10. The application of the insulating epoxy material as described in any one of claims 1-6 in the preparation of GIS terminal products.

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