High-heat-resistance and high-toughness epoxy composite material for direct-current casing pipe and preparation method thereof

Abstract

The invention discloses a high-heat-resistance and high-toughness epoxy composite material for a direct current sleeve and a preparation method of the high-heat-resistance and high-toughness epoxy composite material. The epoxy composite material is prepared from the following raw materials in parts by weight: 100-120 parts of epoxy resin, 500-1000 parts of a solvent, 100-140 parts of a curing agent, 80-120 parts of a toughening agent, 1-10 parts of an accelerant and 1-5 parts of a defoaming agent, wherein the curing agent is an anhydride curing agent which contains at least two anhydride groups and has a rigid molecular structure; the flexibilizer is a long-chain compound containing at least two amino groups and having a flexible molecular structure. The prepared epoxy composite material not only can keep excellent insulating property and mechanical strength in a high-temperature environment, but also shows good toughness when being impacted or stressed, so that the reliability of the direct-current bushing is remarkably improved, and the service life of the direct-current bushing is remarkably prolonged; therefore, a safer, more economical and more reliable DC bushing solution can be brought to the power industry, and the power system is promoted to develop towards a more efficient and more environment-friendly direction.

Description

Technical Field

[0001] The invention relates to a high-heat-resistant and high-toughness epoxy composite material for a DC bushing and a preparation method thereof, belonging to the technical field of composite materials and DC bushings for power transmission. Background Art

[0002] With the development of modern power systems, the performance requirements for power equipment are getting higher and higher, especially for DC bushings working in high temperature and high voltage environments. As a key component connecting high-voltage DC transmission lines and substations, the performance of DC bushings is directly related to the safety and stability of the entire power system. Once a flashover occurs, it will cause the line to stop operating in a single pole, damage the main body and surrounding precision equipment, and the consequences are very serious.

[0003] However, although traditional epoxy resin composite materials have certain insulation performance and mechanical strength, their performance will gradually decline under the conditions of long-term high temperature and mechanical stress, resulting in reduced insulation performance and even failure. At the same time, when these epoxy resin composite materials are applied to DC bushings, they will also cause the DC bushings to have deficiencies in heat resistance and toughness, which not only limits their application in extreme environments, but also increases the cost of maintenance and replacement.

[0004] Therefore, developing an epoxy resin composite material with both high heat resistance and high toughness is of great significance for improving the performance of DC bushings and meeting the needs of modern power systems. Summary of the invention

[0005] The purpose of the present invention is to provide a high heat-resistant and high-toughness epoxy composite material for a DC bushing and a preparation method thereof. The epoxy composite material can not only maintain excellent insulation performance and mechanical strength under high temperature environment, but also exhibit good toughness when subjected to impact or stress, thereby significantly improving the reliability and service life of the DC bushing, and then being able to bring safer, more economical and more reliable DC bushing solutions to the power industry, and promote the development of the power system towards a more efficient and environmentally friendly direction.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A high-heat-resistant and high-toughness epoxy composite material for a DC bushing, wherein the raw materials include the following components in parts by weight: 100 to 120 parts of epoxy resin, 500 to 1000 parts of solvent, 100 to 140 parts of curing agent, 80 to 120 parts of toughening agent, 1 to 10 parts of accelerator, and 1 to 5 parts of defoaming agent;

[0008] Wherein, the curing agent is an anhydride curing agent containing at least two anhydride groups and having a rigid molecular structure;

[0009] The toughening agent is a long-chain compound containing at least two amino groups and having a flexible molecular structure.

[0010] Preferably, the epoxy resin is a combination of one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and alicyclic epoxy resin, specifically, the epoxy resin is a combination of one or more of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hexahydrophthalic acid diglycidyl ester and 3,4-epoxycyclohexanecarboxylic acid methyl ester.

[0011] Preferably, the curing agent is a combination of one or more of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-(acetylene-1,2-diyl) diphthalic anhydride and hexafluoro dianhydride.

[0012] Preferably, the toughening agent is a combination of one or more of 1,3-propylenediamine, 1,5-pentanediamine, 1,7-diaminoheptane, and 1,10-decanediamine.

[0013] Preferably, the solvent is N,N-dimethylpropionamide;

[0014] The accelerator is one or a combination of N,N-dimethylbenzylamine and 2-ethyl-4-methylimidazole;

[0015] The defoaming agent is polydimethylsiloxane.

[0016] The preparation method of any of the above-mentioned high heat-resistant and high-toughness epoxy composite materials is specifically as follows:

[0017] The toughening agent and the curing agent are dissolved in a solution to obtain a dissolving solution, and then the epoxy resin and the defoaming agent are added to the dissolving solution, and heated and stirred once under vacuum conditions, and a precast material is obtained after drying; and then the accelerator is added to the precast material, and heated and stirred twice under vacuum conditions to obtain the epoxy composite material.

[0018] Preferably, a step of drying the raw materials is performed before preparing the epoxy composite material, and the drying conditions are: 60-80° C., 2-4 hours.

[0019] Preferably, the conditions for the primary heating and stirring are: 80-100° C., 300-350 r / min, 30-50 min;

[0020] Drying conditions are: under vacuum, 120-150°C, 6-8h;

[0021] The conditions for secondary heating and stirring are: 80-100°C, 300-350r / min, 3-5min.

[0022] The beneficial effects of the present invention are:

[0023] The toughening agent adopts a flexible long-chain compound with two or more amino groups, and the curing agent is a rigid anhydride curing agent containing at least two anhydride groups. The amino groups on the toughening agent can react with the anhydride groups in the curing agent to embed the long-chain toughening agent into the curing agent, which can effectively adjust the rigidity and toughness of the curing agent, thereby achieving a reasonable improvement in the heat resistance and mechanical properties of the epoxy composite material, and effectively improving the production feasibility and convenience of the epoxy composite material, providing reliable guarantee for the production and application of DC bushings.

[0024] At the same time, the curing agent has a rigid molecular structure, which can effectively inhibit the displacement of molecular segments of epoxy composite materials under stress and high temperature, thus providing a basis for the heat resistance of epoxy composite materials. The curing agent with a higher melting point is blended with epoxy resin and other reagents by dissolution blending, thus achieving the blending of high melting point curing agent and epoxy resin, solving the problem of difficult preparation process of high heat-resistant epoxy composite materials. DETAILED DESCRIPTION

[0025] The invention provides a high-heat-resistant and high-toughness epoxy composite material for a DC bushing. The raw materials thereof include the following components in parts by weight: 100 to 120 parts of epoxy resin, 500 to 1000 parts of solvent, 100 to 140 parts of curing agent, 80 to 120 parts of toughening agent, 1 to 10 parts of accelerator, and 1 to 5 parts of defoaming agent.

[0026] Among them, the epoxy resin is a combination of one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and alicyclic epoxy resin, including the epoxy resin is bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hexahydrophthalic acid diglycidyl ester, 3,4-epoxycyclohexanecarboxylic acid methyl ester.

[0027] The curing agent is an anhydride curing agent containing at least two anhydride groups, preferably a combination of one or more of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-(acetylene-1,2-diyl) diphthalic anhydride and hexafluorodianhydride.

[0028] The toughening agent is a long-chain compound containing at least two amino groups, preferably a combination of one or more of 1,3-propylenediamine, 1,5-pentanediamine, 1,7-diaminoheptane, and 1,10-decanediamine.

[0029] The solvent is N,N-dimethylpropionamide; the accelerator is one or a combination of N,N-dimethylbenzylamine and 2-ethyl-4-methylimidazole; and the defoaming agent is polydimethylsiloxane.

[0030] The preparation method of the epoxy composite material is specifically as follows:

[0031] 1) Place epoxy resin, curing agent, toughening agent, accelerator and defoaming agent in a drying oven to remove moisture from the reagents. The drying temperature is 60-80°C and the drying time is 2-4 hours;

[0032] 2) Dissolve the toughening agent and curing agent in the solvent and stir thoroughly. Depending on the type of toughening agent and curing agent, the dissolving liquid can also be gradually added to the toughening agent and curing agent until they are completely dissolved. The dissolution is carried out at room temperature. The stirring rate during the dissolution is 300-350r / min. After the dissolution, continue to stir for 25-30 minutes;

[0033] 3) Add epoxy resin and defoamer to the solution in step 2) and heat and stir under vacuum. Use a vacuum machine to ensure the vacuum environment inside the container; the stirring temperature is 80-100°C, the stirring speed is 300-350r / min, and the stirring time is 30-50min;

[0034] 4) Place the dissolved solution after stirring into a vacuum drying oven for drying to obtain epoxy resin precast material. Use a vacuum machine to ensure the vacuum environment inside the drying oven, the drying temperature is 120-150°C, and the drying time is 6-8h;

[0035] 5) Add the accelerator to the precast material and continue vacuum heating and stirring. Use a vacuum machine to ensure the vacuum environment inside the container, the stirring temperature is 80-100°C, the stirring speed is 300-350r / min, and the stirring time is 3-5min.

[0036] The preparation method of the epoxy composite sample is as follows:

[0037] The epoxy composite material after the step 5) in the preparation method of the epoxy composite material is poured into a mold for curing. The curing is divided into pre-curing and post-curing, the pre-curing time is 4 to 6 hours, the curing temperature is 100 to 120°C; the post-curing time is 12 to 16 hours, and the post-curing temperature is 150 to 170°C; after the curing is completed, the mold is demoulded to obtain an epoxy composite sample.

[0038] The present invention will be specifically described below in conjunction with the embodiments.

[0039] The purchasing sources of some reagents in the examples and comparative examples of the present invention are shown in Table 1.

[0040] Table 1 Sources of procurement of some reagents

[0041]

[0042]

[0043] Table 2 shows the specific components for preparing epoxy composite materials in specific examples and comparative examples, and specifies the amount (parts) of each component.

[0044] Table 2 Types and dosages of some reagents in the examples and comparative examples (parts)

[0045]

[0046] The preparation method of the epoxy composite material and the epoxy composite sample in the above-mentioned embodiment and comparative example comprises the following steps:

[0047] 1) Place epoxy resin, curing agent, toughening agent, accelerator and defoaming agent in a drying oven to remove moisture from the reagents. The drying temperature is 80°C and the drying time is 4 hours;

[0048] 2) Dissolve the toughening agent and curing agent in the solvent at room temperature. Stir at a rate of 350 r / min during dissolution, and continue stirring for 30 minutes after dissolution;

[0049] 3) Add epoxy resin and defoamer to the solution and heat and stir under vacuum. Use a vacuum machine to ensure the vacuum environment inside the container, with a stirring temperature of 100°C, a stirring rate of 350r / min, and a stirring time of 50min;

[0050] 4) Place the dissolved solution after stirring into a vacuum drying oven for drying to obtain epoxy resin precast material. Use a vacuum machine to ensure the vacuum environment inside the drying oven, the drying temperature is 130°C, and the drying time is 8 hours;

[0051] 5) Add the accelerator to the precast material and continue vacuum heating and stirring. Use a vacuum machine to ensure the vacuum environment inside the container, the stirring temperature is 80-100°C, the stirring speed is 350r / min, and the stirring time is 4min;

[0052] 6) After stirring, pour the precast material into the mold for curing. The curing process is divided into pre-curing and post-curing. The pre-curing time is 6 hours and the curing temperature is 120°C; the post-curing time is 16 hours and the post-curing temperature is 170°C.

[0053] 7) After curing is completed, demoulding is performed to obtain an epoxy composite sample.

[0054] Test Case

[0055] The mechanical properties and thermal properties of the epoxy composite samples prepared in the above Examples 1-3 and Comparative Examples 1-3 were tested, and the standards for each test are as follows:

[0056] Bending strength: GB / T 2570-1995 Test method for bending properties of resin castings;

[0057] Impact strength: GB / T 2571-1995 Impact test method for resin castings;

[0058] Tensile shear strength: GB / T 7124-2008 Determination of tensile shear strength of adhesives;

[0059] Glass transition temperature: GB / T 19466.2-2004 Plastics Differential Scanning Calorimetry (DSC) Part 2, Determination of glass transition temperature.

[0060] The test results of the bending strength, impact strength, tensile shear strength and glass transition temperature of the epoxy composite samples obtained in Examples 1-3 and Comparative Examples 1-3 are shown in Table 3.

[0061] Table 3 Test results of flexural strength, impact strength, tensile shear strength and glass transition temperature of epoxy composite samples

[0062]

[0063] It can be seen from the test results in Table 3 that the mechanical properties and heat resistance of Examples 1-3 are better than those of Comparative Examples 1-3. In Comparative Example 1, no flexible toughening agent was used for modification, so the toughness of the epoxy composite was insufficient, and the accumulation of internal stress caused its bending strength, impact strength and tensile shear strength to decrease. In Comparative Example 2, rigid 1,2-phenylenediamine was used as a toughening agent for modification. Although the rigidity of the epoxy composite was enhanced, the increase in internal stress caused its mechanical properties to be even lower than those of Comparative Example 1. In Comparative Example 3, flexible polysebacic anhydride was used as a curing agent, which resulted in the lack of rigidity of the epoxy composite and insufficient degree of curing, which was reflected in the performance of the epoxy composite sample as a decrease in its mechanical strength and heat resistance.

[0064] The reason why the mechanical properties and heat resistance of Examples 1-3 are relatively excellent is that the curing agent used has a rigid molecular structure, which can effectively inhibit the displacement of molecular chain segments of the epoxy composite material under stress and high temperature, and provide a basis for the heat resistance of the epoxy composite material; at the same time, the curing agent also contains at least two anhydride groups, and the toughening agent contains two or more amino groups and has a flexible molecular structure. The amino groups on the toughening agent can react with the anhydride groups in the curing agent to embed the long-chain toughening agent into the curing agent, and the rigidity and toughness of the curing agent are reasonably adjusted, so that the heat resistance and mechanical properties of the epoxy composite sample are reasonably improved.

[0065] The above is only a preferred implementation of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the patent of the present invention. These improvements and modifications should also be regarded as the protection scope of the patent of the present invention.

Claims

1. A high heat-resistant and high-toughness epoxy composite material for DC bushing, characterized in that: The raw materials include the following components in parts by weight: 100-120 parts of epoxy resin, 500-1000 parts of solvent, 100-140 parts of curing agent, 80-120 parts of toughening agent, 1-10 parts of accelerator, and 1-5 parts of defoaming agent; Wherein, the curing agent is an anhydride curing agent containing at least two anhydride groups and having a rigid molecular structure; The toughening agent is a long-chain compound containing at least two amino groups and having a flexible molecular structure.

2. The high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 1, characterized in that: The epoxy resin is a combination of one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and alicyclic epoxy resin.

3. The high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 2, characterized in that: The epoxy resin is a combination of one or more of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hexahydrophthalic acid diglycidyl ester, and 3,4-epoxycyclohexanecarboxylic acid methyl ester.

4. The high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 1, characterized in that: The curing agent is a combination of one or more of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-(acetylene-1,2-diyl) diphthalic anhydride and hexafluoro dianhydride.

5. The high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 1, characterized in that: The toughening agent is a combination of one or more of 1,3-propylenediamine, 1,5-pentanediamine, 1,7-diaminoheptane, and 1,10-decanediamine.

6. The high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 1, characterized in that: The solvent is N,N-dimethylpropionamide.

7. The high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 1, characterized in that: The accelerator is one or a combination of N,N-dimethylbenzylamine and 2-ethyl-4-methylimidazole; The defoaming agent is polydimethylsiloxane.

8. The method for preparing the high heat-resistant and high-toughness epoxy composite material for DC bushing according to any one of claims 1 to 7, characterized in that: Specifically: The toughening agent and the curing agent are dissolved in a solvent to obtain a dissolving solution, and then the epoxy resin and the defoaming agent are added to the dissolving solution, and heated and stirred once under vacuum conditions, and a precast material is obtained after drying; then the accelerator is added to the precast material, and heated and stirred twice under vacuum conditions to obtain the epoxy composite material.

9. The method for preparing the high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 8, characterized in that: Before preparing the epoxy composite material, a step of drying the raw materials is also carried out, and the drying conditions are: 60-80° C., 2-4 hours.

10. The method for preparing the high heat-resistant and high-toughness epoxy composite material for DC bushing according to claim 8, characterized in that The conditions for primary heating and stirring are: 80-100°C, 300-350r / min, 30-50min; Drying conditions are: under vacuum, 120-150°C, 6-8h; The conditions for secondary heating and stirring are: 80-100°C, 300-350r / min, 3-5min.

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