Hygrothermal aging-resistant high-temperature vulcanized silicone rubber as well as preparation method and application thereof

Abstract

The invention provides damp-heat aging resistant high-temperature vulcanized silicone rubber as well as a preparation method and application thereof, and relates to the technical field of vulcanized silicone rubber. The vulcanized silicone rubber provided by the invention comprises the following components in parts by mass: 100 parts of raw silicone rubber, 100-140 parts of a flame retardant, 30-60 parts of a reinforcing filler, 3-8 parts of hydroxyl silicone oil, 1-2 parts of a vulcanizing agent, 1-2 parts of a silane coupling agent and 2-6 parts of yttrium oxide powder. The vulcanized silicone rubber provided by the invention is relatively low in moisture absorption rate in a high-humidity and high-temperature environment, so that the long-term stability of an insulator prepared from the vulcanized silicone rubber in a power grid operation process is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of vulcanized silicone rubber, and in particular to a high-temperature vulcanized silicone rubber resistant to moisture and heat aging, and a preparation method and application thereof. Background Art

[0002] High temperature vulcanized silicone rubber materials have excellent electrical insulation properties and high weather resistance, ozone resistance, high temperature and low temperature resistance, etc., and are now widely used in electronic and electrical, aerospace and other industries. High temperature vulcanized silicone rubber has been widely used in power transmission systems for more than 20 years due to its excellent performance. In high temperature and high humidity areas (areas where high temperature and high humidity exist at the same time), the dielectric loss of insulators in AC transmission lines may increase, causing abnormal heating of insulators. High humidity will also reduce the breakdown strength of insulators. All of these threaten the safety of the power system. At the same time, in the past 10 years, my country has built a number of new high-voltage direct current transmission lines, such as the Tianshengqiao-Guangzhou 500 kV transmission line, the Guizhou-Guangdong 500 kV transmission line, the Yunnan-Guangdong 800 kV transmission line, etc. Most of these lines pass through high temperature and high humidity areas. Under the action of the DC electric field, moisture intrusion reduces the volume resistivity of high temperature superconducting materials and seriously reduces the insulation performance of the materials. Therefore, high temperature vulcanized silicone rubber materials used in these fields require better electrical properties and thermal stability.

[0003] Although the high-temperature vulcanized silicone rubber materials currently developed have good high-temperature resistance, if used under high-temperature and humid working conditions, they generally show a high moisture absorption rate. Some composite insulators have been in operation for 10 years, and the moisture absorption rate is as high as 2.5% or more. In addition, when used in a high-temperature and humid environment for a long time, the electrical performance is seriously degraded, causing abnormal heating of the insulator and serious aging failure. This shows that the current high-temperature vulcanized silicone rubber materials are only relatively good in terms of resistance to hot air aging, but there is still a lot of room for research in terms of resistance to wet and hot aging. Therefore, it is urgent to provide a solution to improve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a high-temperature vulcanized silicone rubber resistant to moisture and heat aging and a preparation method and application thereof, which can inhibit the moisture absorption rate of silicone rubber in a high-humidity and high-temperature environment, thereby ensuring the long-term stability of insulators prepared from vulcanized silicone rubber during power grid operation.

[0005] In the first aspect, the present invention provides a high-temperature vulcanized silicone rubber resistant to moisture and heat aging, which includes, by mass, 100 parts of silicone rubber raw rubber, 100-140 parts of flame retardant, 30-60 parts of reinforcing filler, 3-8 parts of hydroxy silicone oil, 1-2 parts of vulcanizing agent, 1-2 parts of silane coupling agent and 2-6 parts of yttrium oxide powder.

[0006] The vulcanized silicone rubber provided by the present invention uses silicone rubber raw rubber as a matrix, and the addition of flame retardants and reinforcing fillers can comprehensively improve the flame retardant properties and mechanical strength of the silicone rubber. The addition of yttrium oxide powder can effectively improve the hygroscopicity of the vulcanized silicone rubber in a high temperature and high humidity environment, thereby improving the mechanical properties and electrical conductivity of the silicone rubber material in a high temperature and high humidity environment. In addition, the addition of a silane coupling agent can improve the compatibility of yttrium oxide powder, flame retardants and reinforcing fillers in the silicone rubber raw rubber. The addition of hydroxy silicone oil can effectively reduce the viscosity of the silicone rubber and improve the processing performance and mechanical properties.

[0007] Optionally, the flame retardant includes at least one of hydrated aluminum oxide powder and aluminum oxide powder.

[0008] Optionally, the flame retardant has an average particle size of 1 μm.

[0009] Optionally, the average particle size of the yttrium oxide powder is 1 μm.

[0010] Optionally, the reinforcing filler includes fumed silica.

[0011] Optionally, the vulcanizing agent includes 2,5-dimethyl-2,5-(tert-butylperoxy)hexane.

[0012] Optionally, the silane coupling agent includes at least one of KH550, KH560 and KH570.

[0013] Optionally, the silicone rubber comprises methyl vinyl silicone rubber.

[0014] Optionally, the hydroxyl content of the hydroxyl silicone oil is 7-9%.

[0015] Optionally, the viscosity of the hydroxy silicone oil is 300,000-400,000 cp.

[0016] In a second aspect, the present invention also provides a method for preparing any of the above-mentioned optional vulcanized silicone rubbers, comprising: mixing silicone rubber raw rubber, flame retardant, reinforcing filler, hydroxy silicone oil, silane coupling agent and yttrium oxide powder to obtain a mixture; mixing the mixture with a vulcanizing agent and performing two-stage vulcanization to obtain a high-temperature vulcanized silicone rubber that is resistant to moisture and heat aging.

[0017] Optionally, the raw silicone rubber is pretreated at 55-65° C., and then continuously kneaded and a flame retardant, yttrium oxide powder, reinforcing filler, hydroxy silicone oil and silane coupling agent are sequentially added to obtain a mixture.

[0018] Optionally, the mixed material is kneaded with a vulcanizing agent to obtain a material to be vulcanized, the material to be vulcanized is kept at 20-30°C for 22-26 hours, and then transferred to 165-175°C and 195-205°C for vulcanization treatment in sequence to obtain a high-temperature vulcanized silicone rubber resistant to moisture and heat aging.

[0019] In a third aspect, the present invention further provides an application of any of the above-mentioned optional vulcanized silicone rubbers, wherein the application includes preparing an insulator. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are 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. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0021] The invention provides a high-temperature vulcanized silicone rubber resistant to moisture and heat aging, which comprises, by mass, 100 parts of silicone rubber raw rubber, 100-140 parts of flame retardant, 30-60 parts of reinforcing filler, 3-8 parts of hydroxy silicone oil, 1-2 parts of vulcanizing agent, 1-2 parts of silane coupling agent and 2-6 parts of yttrium oxide powder.

[0022] In fact, silicone rubber raw rubber is used as the matrix in vulcanized silicone rubber, and flame retardants, reinforcing fillers, hydroxy silicone oil, yttrium oxide powder, and silane coupling agents are added thereto to improve the mechanical properties, resistance to moisture and heat aging, anti-hygroscopicity and mechanical properties of the silicone rubber, and vulcanizing agents are added to vulcanize the silicone rubber.

[0023] In some embodiments, the flame retardant includes at least one of hydrated alumina powder and alumina powder. In fact, by adding hydrated alumina or alumina to silicone rubber, the silicone rubber can quickly conduct heat when heated, thereby reducing the temperature of the material surface and inhibiting combustion. At the same time, hydrated alumina can be decomposed into water and alumina when heated. In addition, the cost of hydrated alumina and alumina is relatively low, which can greatly reduce the production cost of silicone rubber products.

[0024] In some embodiments, the average particle size of the flame retardant is 1 μm. In fact, by adding small particles of flame retardant into silicone rubber, when the flame retardant is evenly dispersed therein, a dense and continuous heat conductive network can be formed, thereby effectively conducting the heat of the silicone rubber, which is beneficial to improving the flame retardant efficiency and flame retardant properties.

[0025] In some embodiments, the average particle size of the yttrium oxide powder is 1 μm. By adding small particles of yttrium oxide powder into silicone rubber, the uniform distribution of the yttrium oxide powder in the silicone rubber can be effectively promoted, thereby improving the yttrium oxide powder's inhibition of the moisture absorption process of the silicone rubber in a high temperature and high humidity environment, thereby effectively improving the performance of the silicone rubber in a high temperature and high humidity environment.

[0026] In some embodiments, the reinforcing filler includes fumed silica. In fact, after adding fumed silica, the mechanical properties and heat resistance of silicone rubber can be significantly enhanced, while the anti-aging and weather resistance of silicone rubber can be improved. At the same time, the silicone rubber can be filled and expanded to improve the compatibility of silicone rubber.

[0027] In some embodiments, the silicone rubber includes methyl vinyl silicone rubber.

[0028] In some embodiments, the silane coupling agent includes at least one of KH550, KH560 and KH570. By adding the silane coupling agent to the silicone rubber, the compatibility between the silicone rubber and the flame retardant, reinforcing filler and yttrium oxide powder can be effectively improved, thereby improving the overall performance and structural stability of the silicone rubber.

[0029] In some embodiments, the vulcanizing agent includes 2,5-dimethyl-2,5-(tert-butylperoxy)hexane, which is added into the raw silicone rubber to effectively promote the vulcanization reaction, thereby achieving cross-linking and curing.

[0030] In some embodiments, the hydroxyl content of the hydroxy silicone oil is 7-9, and the viscosity is 300,000-400,000 cp.

[0031] The present invention also provides a method for preparing the vulcanized silicone rubber in any of the above embodiments, comprising:

[0032] S1, mixing silicone rubber, flame retardant, reinforcing filler, hydroxy silicone oil, silane coupling agent and yttrium oxide powder to prepare a mixture;

[0033] S2. The mixture is mixed with a vulcanizing agent and then subjected to two-stage vulcanization to obtain a high-temperature vulcanized silicone rubber resistant to moisture and heat aging.

[0034] In fact, the execution of step S1 includes: pre-treating the silicone rubber at 55-65° C., continuously mixing and sequentially adding flame retardant, yttrium oxide powder, reinforcing filler, hydroxy silicone oil and silane coupling agent to obtain a mixture.

[0035] In fact, when executing step S2, it includes: kneading the mixture with the vulcanizing agent to obtain the material to be vulcanized, keeping the material to be vulcanized at 20-30°C for 22-26h, transferring it to 165-175°C and 195-205°C for vulcanization treatment in turn, and obtaining the high temperature vulcanized silicone rubber resistant to moisture and heat aging.

[0036] The present invention also provides an application of the vulcanized silicone rubber. For example, the vulcanized silicone rubber can be made into an umbrella skirt structure outside an insulator.

[0037] Example 1

[0038] This embodiment 1 provides a method for preparing a high-temperature vulcanized silicone rubber resistant to moisture and heat aging, comprising the following steps:

[0039] S1. Add 200 g of methyl vinyl silicone rubber into an internal mixer, mix for 5 min at a speed of 40 rpm, a filling factor of 0.8, and a cavity temperature of 60° C., then add 240 g of alumina powder (with a particle size of 1 μm) and 8.5 g of yttrium oxide powder (with a particle size of 1 μm) and mix for 20 min, then add 80 g of fumed silica and mix for 30 min, then add 10 g of hydroxy silicone oil (purchased from Guangdong Xinbo Silicon Materials Co., Ltd.) and 3.2 g of KH560 silane coupling agent and mix for 15 min to obtain a mixture;

[0040] S2. Add 3.2 g of 2,5-dimethyl-2,5-(tert-butylperoxy)hexane into an internal mixer and mix with the mixture for 20 minutes to obtain the material to be vulcanized. After the material to be vulcanized is placed at room temperature for 24 hours, it is vulcanized on a flat vulcanizer at a pressure of 13 MPa and a vulcanization temperature of 170°C for 20 minutes, and then vulcanized at 200°C for 4 hours. After cooling to room temperature, a high-temperature vulcanized silicone rubber resistant to moisture and heat aging is obtained.

[0041] Example 2

[0042] This embodiment 2 provides a method for preparing a high-temperature vulcanized silicone rubber resistant to moisture and heat aging, comprising the following steps:

[0043] S1. Add 200 g of methyl vinyl silicone rubber (purchased from Suzhou Junxin Plastic Co., Ltd.) into an internal mixer, mix for 5 min at a speed of 40 rpm, a filling factor of 0.8, and a cavity temperature of 60°C, then add 240 g of alumina powder (particle size of 1 μm) and 6 g of yttrium oxide powder (particle size of 1 μm) and mix for 20 min, then add 80 g of fumed silica (purchased from Qinghe County Kete New Material Technology Co., Ltd.) and mix for 30 min, then add 10 g of hydroxy silicone oil (purchased from Guangdong Xinbo Silicon Material Co., Ltd.) and 3.2 g of KH560 silane coupling agent and mix for 15 min to obtain a mixture;

[0044] S2. Add 3.2 g of 2,5-dimethyl-2,5-(tert-butylperoxy)hexane into an internal mixer and mix with the mixture for 20 minutes to obtain the material to be vulcanized. After the material to be vulcanized is placed at room temperature for 24 hours, it is vulcanized on a flat vulcanizer at a pressure of 13 MPa and a vulcanization temperature of 170°C for 20 minutes, and then vulcanized at 200°C for 4 hours. After cooling to room temperature, a high-temperature vulcanized silicone rubber resistant to moisture and heat aging is obtained.

[0045] Example 3

[0046] This embodiment 3 provides a method for preparing a high-temperature vulcanized silicone rubber resistant to moisture and heat aging, comprising the following steps:

[0047] S1. Add 200 g of methyl vinyl silicone rubber into an internal mixer, mix for 5 min at a speed of 40 rpm, a filling factor of 0.8, and a cavity temperature of 60° C., then add 240 g of alumina powder (particle size of 1 μm) and 12 g of yttrium oxide powder (particle size of 1 μm) and mix for 20 min, then add 80 g of fumed silica and mix for 30 min, then add 10 g of hydroxy silicone oil (purchased from Guangdong Xinbo Silicon Materials Co., Ltd.) and 3.2 g of KH560 silane coupling agent and mix for 15 min to obtain a mixture;

[0048] S2. Add 3.2 g of 2,5-dimethyl-2,5-(tert-butylperoxy)hexane into an internal mixer and mix with the mixture for 20 minutes to obtain the material to be vulcanized. After the material to be vulcanized is placed at room temperature for 24 hours, it is vulcanized on a flat vulcanizer at a pressure of 13 MPa and a vulcanization temperature of 170°C for 20 minutes, and then vulcanized at 200°C for 4 hours. After cooling to room temperature, a high-temperature vulcanized silicone rubber resistant to moisture and heat aging is obtained.

[0049] Comparative Example 1

[0050] This comparative example 1 provides a method for preparing a high-temperature vulcanized silicone rubber resistant to moisture and heat aging, comprising the following steps:

[0051] D1. Add 200 g of methyl vinyl silicone rubber into an internal mixer, mix for 5 min at a speed of 40 rpm, a filling factor of 0.8, and a cavity temperature of 60° C., then add 240 g of alumina powder (particle size of 1 μm) and 8.5 g of californium oxide powder (particle size of 1 μm) and mix for 20 min, then add 80 g of fumed silica and mix for 30 min, then add 10 g of hydroxy silicone oil (purchased from Guangdong Xinbo Silicon Materials Co., Ltd.) and 3.2 g of KH560 silane coupling agent and mix for 15 min to obtain a mixture;

[0052] D2. Add 3.2 g of 2,5-dimethyl-2,5-(tert-butylperoxy)hexane into an internal mixer and mix with the mixture for 20 minutes to obtain the material to be vulcanized. After the material to be vulcanized is placed at room temperature for 24 hours, it is vulcanized on a flat vulcanizer at a pressure of 13 MPa and a vulcanization temperature of 170°C for 20 minutes, and then placed at 200°C for vulcanization for 4 hours. After cooling to room temperature, a high-temperature vulcanized silicone rubber resistant to moisture and heat aging is obtained.

[0053] Performance Testing

[0054] The high-temperature vulcanized silicone rubber resistant to humidity and heat aging prepared in Examples 1 to 3 and Comparative Example 1 was divided into two parts, and one of them was placed in a humidity and heat aging test box, and accelerated humidity and heat aging treatment was performed for 30 days based on the method described in GB / T15905-1995 "Humidity and Heat Aging Test Method for Vulcanized Rubber", while the other part was not treated as an initial control.

[0055] Based on the DLT 376-2019 standard, the performance tests of high temperature vulcanized silicone rubber treated with wet heat aging and untreated were carried out respectively, and the test results are shown in Tables 1 and 2 below.

[0056] Table 1 Performance test results of high temperature vulcanized silicone rubber without wet heat aging treatment

[0057] Test items Example 1 Example 2 Example 3 Comparative Example 1 Mooney viscosity 20 18 19 18 Tensile strength, MPa 4.9 4.8 4.9 4.5 Elongation at break, % 368 370 365 350 Tear strength, kN / m 11.5 11.5 11.5 10 Shore hardness, ShoreA 62 62 62 60 Moisture absorption rate, % 0 0 0 0 <![CDATA[Volume resistivity, 10^ 13 Q·m]]> 3.1 3.05 3.0 2.2 Thermal decomposition temperature (thermogravimetric), ℃ 543 539 538 534 Resistance to tracking and electrical erosion, Grade TMA4.5 TMA4.5 TMA4.5 TMA4.5 Flame retardant performance, grade FV-0 FV-0 FV-0 FV-0

[0058] Table 2 Performance test results of high temperature vulcanized silicone rubber after wet heat aging treatment

[0059]

[0060]

[0061] It can be seen from Table 1 and Table 2 that the high-temperature vulcanized silicone rubber resistant to moisture and heat aging provided by the present invention can significantly improve the mechanical properties and electrical properties of the silicone rubber by adding yttrium oxide powder, so as to adapt to the working environment of the insulator. In addition, the vulcanized silicone rubber prepared in Examples 1 to 3 has an extremely low moisture absorption rate. Before moisture and heat aging, the water absorption rate is 0%, and after 30 days of moisture and heat aging treatment, the moisture absorption rate is only 0.65-0.8%, which is significantly lower than 1% in Comparative Example 1. This shows that the present invention can increase the service life of the vulcanized silicone rubber in a high temperature and high humidity environment by adding yttrium oxide powder.

[0062] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A high temperature vulcanized silicone rubber resistant to moisture and heat aging, It is characterized in that The composition comprises, by weight, 100 parts of silicone rubber raw rubber, 100-140 parts of flame retardant, 30-60 parts of reinforcing filler, 3-8 parts of hydroxy silicone oil, 1-2 parts of vulcanizing agent, 1-2 parts of silane coupling agent and 2-6 parts of yttrium oxide powder.

2. The vulcanized silicone rubber according to claim 1, It is characterized in that The flame retardant includes at least one of hydrated aluminum oxide powder and aluminum oxide powder; and / or, the flame retardant has an average particle size of 1 μm; and / or, the yttrium oxide powder has an average particle size of 1 μm.

3. The vulcanized silicone rubber according to claim 1, It is characterized in that The reinforcing filler includes fumed silica; and / or the vulcanizing agent includes 2,5-dimethyl-2,5-(tert-butylperoxy)hexane; and / or the silane coupling agent includes at least one of KH550, KH560 and KH570; and / or the silicone rubber includes methyl vinyl silicone rubber.

4. The vulcanized silicone rubber according to claim 1, It is characterized in that The hydroxyl content of the hydroxy silicone oil is 7-9%; and / or the viscosity of the hydroxy silicone oil is 300,000-400,000 cp.

5. A method for preparing the vulcanized silicone rubber according to any one of claims 1 to 4, It is characterized in that include: Silicone rubber raw rubber, flame retardant, reinforcing filler, hydroxy silicone oil, silane coupling agent and yttrium oxide powder are kneaded to obtain a mixture; the mixture is mixed with a vulcanizing agent and then subjected to two-stage vulcanization to obtain a high-temperature vulcanized silicone rubber resistant to moisture and heat aging.

6. The preparation method according to claim 5, It is characterized in that The raw silicone rubber is pretreated at 55-65° C., and then continuously kneaded and a flame retardant, yttrium oxide powder, reinforcing filler, hydroxy silicone oil and silane coupling agent are sequentially added to obtain a mixture.

7. The preparation method according to claim 5, It is characterized in that The mixed material is kneaded with a vulcanizing agent to obtain a material to be vulcanized, and the material to be vulcanized is kept at 20-30°C for 22-26 hours, and then transferred to 165-175°C and 195-205°C for vulcanization treatment in sequence to obtain a high-temperature vulcanized silicone rubber resistant to moisture and heat aging.

8. A use of the vulcanized silicone rubber according to any one of claims 1 to 4, It is characterized in that The application includes the preparation of insulators.

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