Silicone rubber for composite insulator, preparation method of silicone rubber and insulator

Abstract

The invention belongs to the technical field of rubber products, and provides silicone rubber for a composite insulator, a preparation method of the silicone rubber and the insulator, and the preparation method comprises the following steps: S1, mixing methyl vinyl phenyl silicone rubber and glycidyl methacrylate grafted silicone rubber in parts by weight, adding fumed silica and modified magnesium hydroxide, and uniformly stirring to obtain a silicone rubber mixture; continuously mixing, adding silicone oil, triethanolamine and a vulcanizing agent, stirring and mixing, and standing to obtain a mixed rubber material; s2, the mixed rubber material is put into an open mill to be mixed, a vulcanizing agent is added, thin passing and sheet discharging are conducted, standing is conducted, and rubber sheets are obtained; s3, putting the rubber sheet into a mold for molding, and then carrying out vulcanization reaction to obtain the silicone rubber material. The silicone rubber material provided by the invention has excellent mechanical property, flame retardant property, anti-aging property and electrical insulation property. Meanwhile, the preparation process is simple, raw materials are easy to obtain, cost is low, and wide application prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber products, and in particular relates to silicone rubber for composite insulators, a preparation method thereof and an insulator. Background Art

[0002] Composite insulators, also known as silicone rubber insulators, have the advantages of light weight, good anti-pollution performance, strong anti-vandalism performance, etc., and are increasingly popular among users, becoming the main force in the insulator industry in power grid transformation projects. Compared with traditional porcelain insulators and glass insulators, silicone rubber composite insulators have the advantages of light weight, not easy to break, good hydrophobicity, strong anti-pollution flashover ability, and easy manufacturing and maintenance.

[0003] At present, the widely used silicone rubber shed is generally composed of three main components: methyl vinyl silicone rubber, aluminum hydroxide and fumed silica, and then combined with structure control agents, colorants, etc., and a special mesh structure organic material is obtained after high-temperature vulcanization and cross-linking, which gives the composite insulator excellent electrical insulation, mechanical properties and weather resistance. However, as an external insulation material used outdoors for a long time, the silicone rubber shed sheath will gradually age under the long-term effects of moisture, surface discharge, ultraviolet rays, temperature, salt spray and other factors, and the surface hydrophobicity, physical and mechanical properties and electrical properties of the silicone rubber composite insulator will decay due to aging, which may lead to flashover accidents in severe cases. It can be seen that the lower mechanical properties are very unfavorable for the maintenance of electrical and physical mechanical properties of composite insulators during the aging process. Chinese invention patent CN201510125814.2 discloses a high-voltage electrical corrosion-resistant silicone rubber composition for composite insulators and its preparation method. It improves the electrical corrosion resistance of the silicone rubber composition for composite insulators by adding thermally conductive metal oxide nanoparticles, and retains good mechanical properties. However, its hydrophobicity is poor and its pollution flashover resistance is average, resulting in average anti-aging performance and short service life of the insulator. Chinese invention patent CN201510066190.1 discloses a fluorosilicone rubber for aging-resistant porcelain composite insulators and its application. It is prepared from raw materials such as fluororubber raw rubber, silicone rubber compound, aluminum hydroxide, fumed silica, dipentadienyl sulfide agent and polytetrafluoroethylene powder, and has excellent tear strength and aging resistance. However, the raw materials of the composite insulator contain fluorine, which has a greater impact on the environment, and the electrical properties of the insulator such as high-voltage electrical corrosion resistance and anti-puncture resistance are average.

[0004] Therefore, in order to improve the stability of composite insulators during operation, improving the aging resistance of silicone rubber composite materials while maintaining their excellent electrical properties is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the problem that rubber insulators are prone to aging during actual application, which causes the hydrophobicity, mechanical properties and electrical properties of the rubber insulator surface to decay due to aging, the present invention provides a silicone rubber for a composite insulator, a preparation method thereof and an insulator.

[0006] The purpose of the present invention can be achieved through the following technical solutions: The first aspect of the present invention provides a silicone rubber for a composite insulator, comprising the following raw materials in parts by weight: 90-100 parts of methyl vinyl phenyl silicone rubber; 16-20 parts of glycidyl methacrylate grafted silicone rubber; 30-40 parts of fumed silica; 20-30 parts of modified magnesium hydroxide; 4.5-8 parts of silicone oil; 0.5-1 part of triethanolamine; 2 to 3 parts of vulcanizing agent.

[0007] As a further embodiment of the present invention, the modified magnesium hydroxide is prepared by the following steps: Add magnesium hydroxide to an ethanol aqueous solution, adjust the pH value to 9.8-10.2, perform ultrasonic treatment for 2-2.5 hours, heat to 55-60° C. under a nitrogen atmosphere, add a modified silane coupling agent, continue the reaction for 4.5-5 hours, cool to room temperature, centrifuge, filter, wash and then vacuum dry to obtain modified magnesium hydroxide.

[0008] As a further embodiment of the present invention, the usage ratio of magnesium hydroxide, ethanol aqueous solution and modified silane coupling agent is 8.5-10 g:100 mL:4.4-4.6 g.

[0009] As a further embodiment of the present invention, the modified silane coupling agent is prepared by the following steps: 2-Mercaptobenzimidazole and silane coupling agent KH-590 were added to acetone, heated to 45-50° C. under nitrogen atmosphere, refluxed with stirring, triethylamine was added, and the reaction was continued with stirring for 4.5-5.0 hours to obtain a modified silane coupling agent.

[0010] As a further embodiment of the present invention, the usage ratio of 2-mercaptobenzimidazole, silane coupling agent KH-590, acetone and triethylamine is 8.6-8.8 g: 6.38-6.43 g: 300 mL: 1.50-1.55 g.

[0011] As a further embodiment of the present invention, the silicone oil is at least one of hydroxy silicone oil, hydrogen silicone oil or dimethyl silicone oil.

[0012] As a further embodiment of the present invention, the vulcanizing agent is at least one of benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, di-tert-butyl peroxide or tert-butyl perbenzoate.

[0013] A second aspect of the present invention provides a method for preparing silicone rubber for a composite insulator, comprising the following steps: S1. Mix methyl vinyl phenyl silicone rubber and glycidyl methacrylate grafted silicone rubber by weight for 20 to 40 minutes, add fumed silica and modified magnesium hydroxide, continue mixing for 30 to 60 minutes, then add silicone oil, triethanolamine and vulcanizing agent, stir and mix, and let stand for 18 to 24 hours to obtain a mixed rubber material; S2, putting the mixed rubber material into an open mill for mixing, adding a vulcanizing agent, thinning 3 to 5 times, discharging the sheet, and letting it stand for 18 to 24 hours to obtain a film; S3, placing the film into a mold for forming and then vulcanizing it to obtain a silicone rubber material.

[0014] As a further solution of the present invention, the vulcanization temperature is 160-185° C., the vulcanization pressure is 10-13 MPa, and the vulcanization time is 12-20 min.

[0015] A third aspect of the present invention provides an insulator, comprising the silicone rubber described above.

[0016] Beneficial effects of the present invention: The silicone rubber material provided in the present invention is prepared by mixing and vulcanizing methyl vinyl phenyl silicone rubber, glycidyl methacrylate grafted silicone rubber, fumed silica, modified magnesium hydroxide, silicone oil, triethanolamine and a vulcanizing agent to obtain a silicone rubber material having excellent mechanical properties, flame retardant properties, anti-aging properties and electrical insulation properties. The preparation method provided is simple, the raw materials are easily available, the cost is economical, and the silicone rubber material has broad application prospects.

[0017] The silicone rubber material of the composite insulator of the present invention adopts methyl vinyl phenyl silicone rubber as a matrix, and the phenyl side group structure in the structure can effectively inhibit the rearrangement of Si-O, prevent the occurrence of ring degradation reaction, thereby reducing the thermal degradation rate of the silicone rubber material and improving the thermal stability of the silicone rubber material. At the same time, the presence of phenyl can inhibit the oxidation of the side group and the formation of steric hindrance on the silicon oxygen chain, making the main chain more difficult to degrade, further improving the thermal stability of the silicone rubber material, improving the aging resistance, and significantly extending the service life of the product.

[0018] In the present invention, fumed silica and modified magnesium hydroxide are used as fillers. Fumed silica has a smaller particle size and can be well dispersed in silicone rubber, further improving the mechanical strength of silicone rubber. The modified magnesium hydroxide used is coated between the layers and on the surface of magnesium hydroxide by 2-mercaptobenzimidazole through a silane coupling agent KH-590, thereby obtaining magnesium hydroxide with anti-aging function. On the one hand, the compatibility and dispersibility of magnesium hydroxide and rubber matrix are improved; on the other hand, 2-mercaptobenzimidazole is grafted on the surface of magnesium hydroxide, which can effectively improve the anti-aging performance of magnesium hydroxide. Compared with the traditional direct addition of antioxidant, the problem that the antioxidant is easy to migrate out of the rubber matrix in a high temperature or liquid environment is solved, and the migration of the antioxidant is avoided to produce a toxic effect on the surrounding environment. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1 This embodiment provides a modified magnesium hydroxide, and the preparation steps are as follows: S1, adding 8.6 g of 2-mercaptobenzimidazole and 6.38 g of silane coupling agent KH-590 to 300 mL of acetone, heating to 45° C. under nitrogen atmosphere for reflux stirring, adding 1.50 g of triethylamine, and continuing to stir and react for 4.5 h to obtain a modified silane coupling agent; S2. Add 8.5 g of magnesium hydroxide to 100 mL of ethanol aqueous solution (the volume ratio of anhydrous ethanol to deionized water is 9:2), adjust the pH value to 9.8 with ammonia water, ultrasonically treat for 2 hours, heat to 55°C under a nitrogen atmosphere, add 4.4 g of modified silane coupling agent, continue to react for 4.5 hours, cool to room temperature, centrifuge and filter, wash, and then place in a vacuum oven at 45°C to dry for 48 hours to obtain modified magnesium hydroxide.

[0021] Example 2 This embodiment provides a modified magnesium hydroxide, which is different from Embodiment 1 only in that step S1 is different: S1. Add 8.8 g of 2-mercaptobenzimidazole and 6.43 g of silane coupling agent KH-590 into 300 mL of acetone, heat to 45° C. under nitrogen atmosphere, reflux with stirring, add 1.53 g of triethylamine, continue stirring and reacting for 4.5 h, and obtain a modified silane coupling agent.

[0022] Example 3 This embodiment provides a modified magnesium hydroxide, which is different from Embodiment 1 only in that step S2 is different: S2. Add 10 g of magnesium hydroxide to 100 mL of ethanol aqueous solution (the volume ratio of anhydrous ethanol to deionized water is 9:2), adjust the pH value to 10.2 with ammonia water, ultrasonically treat for 2 h, heat to 55 ° C under a nitrogen atmosphere, add 4.4 g of modified silane coupling agent, continue to react for 4.5 h, cool to room temperature, centrifuge and filter, wash, and then place in a vacuum oven at 45 ° C for 48 h to obtain modified magnesium hydroxide.

[0023] Example 4 This embodiment provides a silicone rubber for a composite insulator and an insulator: A silicone rubber for composite insulators, comprising the following raw materials in parts by weight: 90 parts of methyl vinyl phenyl silicone rubber, 16 parts of glycidyl methacrylate grafted silicone rubber, 30 parts of fumed silica, 20 parts of modified magnesium hydroxide in Example 1, 4.5 parts of hydroxy silicone oil, 0.5 parts of triethanolamine, and 2 parts of benzoyl peroxide.

[0024] The preparation steps of the composite insulator silicone rubber are as follows: S1. Mix methyl vinyl phenyl silicone rubber and glycidyl methacrylate grafted silicone rubber by weight for 20 minutes, add fumed silica and modified magnesium hydroxide, continue mixing for 30 minutes, then add silicone oil, triethanolamine and vulcanizing agent, stir and mix, and let stand for 18 hours to obtain a mixed rubber material; S2, putting the mixed rubber material into an open mill for mixing, adding a vulcanizing agent, thinning it 3 times, discharging it into a sheet, and letting it stand for 18 hours to obtain a film; S3. Place the film into a mold for forming and then perform a vulcanization reaction at a vulcanization temperature of 160° C., a vulcanization pressure of 10 MPa, and a vulcanization time of 20 min to obtain a silicone rubber material.

[0025] The insulator comprises the silicone rubber prepared as above.

[0026] Example 5 Compared with Example 4, the only difference is that the types of modified magnesium hydroxide are different: The modified magnesium hydroxide in Example 1 is replaced by the modified magnesium hydroxide in Example 2, and the amount used remains unchanged.

[0027] Example 6 Compared with Example 4, the only difference is that the types of modified magnesium hydroxide are different: The modified magnesium hydroxide in Example 1 is replaced by the modified magnesium hydroxide in Example 3, and the amount used remains unchanged.

[0028] Example 7 Compared with Example 4, the only difference is that the raw material components of the silicone rubber for the composite insulator are different: A silicone rubber for composite insulators, comprising the following raw materials in parts by weight: 100 parts of methyl vinyl phenyl silicone rubber, 18 parts of glycidyl methacrylate grafted silicone rubber, 35 parts of fumed silica, 28 parts of modified magnesium hydroxide in Example 1, 6 parts of hydroxy silicone oil, 0.8 parts of triethanolamine, and 2.8 parts of benzoyl peroxide.

[0029] Example 8 Compared with Example 4, the only difference is that the preparation steps of the silicone rubber for composite insulators are different: S3. Place the film into a mold for forming and then perform a vulcanization reaction at a vulcanization temperature of 180° C., a vulcanization pressure of 12 MPa, and a vulcanization time of 14 min to obtain a silicone rubber material.

[0030] Comparative Example 1 Compared with Example 4, the only difference is that modified magnesium hydroxide is not added: A silicone rubber for composite insulators, comprising the following raw materials in parts by weight: 90 parts of methyl vinyl phenyl silicone rubber, 16 parts of glycidyl methacrylate grafted silicone rubber, 30 parts of fumed silica, 4.5 parts of hydroxy silicone oil, 0.5 parts of triethanolamine, and 2 parts of benzoyl peroxide.

[0031] Comparative Example 2 Compared with Example 4, the only difference is that the types of modified magnesium hydroxide are different: The modified magnesium hydroxide in Example 1 was replaced with magnesium hydroxide (purchased from Jinan Huifengda Chemical Co., Ltd.), and the amount used remained unchanged.

[0032] Comparative Example 3 Compared with Example 4, the only difference is that the amount of modified magnesium hydroxide is different: 20 parts of the modified magnesium hydroxide in Example 1 were replaced by 15 parts of the modified magnesium hydroxide in Example 1.

[0033] Comparative Example 4 Compared with Example 4, the only difference is that the amount of modified magnesium hydroxide is different: 20 parts of the modified magnesium hydroxide in Example 1 were replaced with 38 parts of the modified magnesium hydroxide in Example 1.

[0034] The following performance tests were conducted on the silicone rubber materials prepared in Examples 4 to 8 and Comparative Examples 1 to 4: (1) Tensile strength and elongation at break: tested according to GB / T 528-2009. (2) Tear strength: tested according to GB / T529-2008. (3) Shore hardness: tested according to GB / T 531.1-2008. (4) Flame retardant properties: tested according to GB / T 10707-2008. (5) Heat aging properties: tested according to GB / T 3512-2001, with hot air aging conditions of 200°C × 48h. (6) Surface resistivity: tested according to GB / T 1692-2008. The test results are shown in Table 1: .

[0035] It can be seen from Table 1 that the tensile strength, elongation at break, tear strength, hardness and aging resistance of the silicone rubber materials prepared in Examples 4-8 are better than those in Comparative Examples 1-4. It can be seen that the silicone rubber provided in the present invention has good mechanical properties, aging resistance, flame retardant properties and electrical insulation properties, and has good application prospects.

[0036] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0037] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Silicone rubber for composite insulators, characterized in that: It includes the following raw materials in parts by weight: 90-100 parts of methyl vinyl phenyl silicone rubber; 16-20 parts of glycidyl methacrylate grafted silicone rubber; 30-40 parts of fumed silica; 20-30 parts of modified magnesium hydroxide; 4.5-8 parts of silicone oil; 0.5-1 part of triethanolamine; 2-3 parts of vulcanizing agent; Wherein, the modified magnesium hydroxide is prepared by the following steps: Add magnesium hydroxide to an ethanol aqueous solution, adjust the pH value to 9.8-10.2, perform ultrasonic treatment for 2-2.5 hours, heat to 55-60° C. under a nitrogen atmosphere, add a modified silane coupling agent, continue the reaction for 4.5-5 hours, cool to room temperature, centrifuge, filter, wash and then vacuum dry to obtain modified magnesium hydroxide.

2. The silicone rubber for composite insulator according to claim 1, characterized in that: The dosage ratio of magnesium hydroxide, ethanol aqueous solution and modified silane coupling agent is 8.5-10g:100mL:4.4-4.6g.

3. The silicone rubber for composite insulator according to claim 1, characterized in that: The modified silane coupling agent is prepared by the following steps: 2-Mercaptobenzimidazole and silane coupling agent KH-590 were added to acetone, heated to 45-50° C. under nitrogen atmosphere, refluxed with stirring, triethylamine was added, and the reaction was continued with stirring for 4.5-5.0 hours to obtain a modified silane coupling agent.

4. The silicone rubber for composite insulator according to claim 3, characterized in that: The usage ratio of 2-mercaptobenzimidazole, silane coupling agent KH-590, acetone and triethylamine is 8.6-8.8g:6.38-6.43g:300mL:1.50-1.55g.

5. The silicone rubber for composite insulator according to claim 1, characterized in that: The silicone oil is at least one of hydroxy silicone oil, hydrogen silicone oil or dimethyl silicone oil.

6. The silicone rubber for composite insulator according to claim 1, characterized in that: The vulcanizing agent is at least one of benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, di-tert-butyl peroxide or tert-butyl perbenzoate.

7. The method for preparing silicone rubber for composite insulators according to claim 1, characterized in that: The following steps are involved: S1. Mix methyl vinyl phenyl silicone rubber and glycidyl methacrylate grafted silicone rubber by weight for 20 to 40 minutes, add fumed silica and modified magnesium hydroxide, continue mixing for 30 to 60 minutes, then add silicone oil, triethanolamine and vulcanizing agent, stir and mix, and let stand for 18 to 24 hours to obtain a mixed rubber material; S2, putting the mixed rubber material into an open mill for mixing, adding a vulcanizing agent, thinning 3 to 5 times, discharging the sheet, and letting it stand for 18 to 24 hours to obtain a film; S3, placing the film into a mold for forming and then vulcanizing it to obtain a silicone rubber material.

8. The method for preparing silicone rubber for composite insulators according to claim 7, characterized in that: The vulcanization temperature is 160-185°C, the vulcanization pressure is 10-13MPa, and the vulcanization time is 12-20min.

9. The insulator according to claim 1, characterized in that: Comprising the silicone rubber as described in any one of claims 1-6.