Two-component silicone heat-conducting flame-retardant pouring sealant and preparation method thereof

Abstract

The application discloses a two-component silicone heat-conducting and flame-retardant pouring sealant and a preparation method thereof. The pouring sealant is composed of A component and B component. The A component comprises, in parts by weight, 60-80 parts of vinyl silicone oil, 150-350 parts of filler, 1-10 parts of dimethyl silicone oil, 0.5-2 parts of catalyst and 0.05-0.1 part of inhibitor. The B component comprises, in parts by weight, 20-40 parts of vinyl silicone oil, 150-350 parts of filler, 20-40 parts of cross-linking agent, 0.5-1 part of coupling agent and 1-5 parts of color paste. Compared with the prior art, the pouring sealant of the application can effectively improve the flow leveling property of the pouring sealant and reduce the viscosity of the sealant by using low-viscosity vinyl silicone oil; the pouring sealant can achieve the effects of high heat conduction and flame retardation by using a plurality of fillers; the cross-linking agent used can make the sealant quickly and completely solidify; the coupling agent added can further reduce the viscosity of the sealant, so that the sealant can maintain excellent flowability even when the content of the filler is high, thereby meeting the requirements of being used for pouring and sealing of high-power transformers.

Description

Technical Field

[0001] This invention relates to the field of silicone potting compound technology, and in particular to a two-component silicone thermally conductive and flame-retardant potting compound and its preparation method. Background Technology

[0002] Silicone potting compounds are widely used in the potting of electronic and electrical appliances due to their excellent resistance to high and low temperatures, weathering, corrosion, and electrical properties. However, pure silicone potting compounds have poor thermal conductivity (only 0.168 W / m·K), making it difficult to meet the requirements of high-temperature environments and high thermal conductivity in transformers; at the same time, their flammability does not meet my country's regulations on the flame retardancy of transformers. Therefore, silicone potting compounds with both thermal conductivity and flame retardancy functions are of great significance to the development of modern industry. Current research reports mainly focus on the single-function modification of silicone potting compounds, either thermal conductivity or flame retardancy. Patent CN116410694A discloses a silicone potting compound, its preparation method, and its application, resulting in a silicone potting compound with a thermal conductivity of 0.5 W / m·K, which is relatively poor. Patent CN104357007A discloses a silicone potting compound, its preparation method, and its application, resulting in a silicone potting compound with good flame retardancy, but its thermal conductivity is less than 1.0 W / m·K, which is difficult to meet the requirements of high-power transformers. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a two-component silicone thermally conductive and flame-retardant potting compound and its preparation method, which has good thermal conductivity and flame-retardant properties, high fluidity, and excellent mechanical properties.

[0004] To achieve this technical objective, this invention provides a two-component silicone thermally conductive and flame-retardant potting compound, comprising component A and component B. Component A, by weight, comprises: 60-80 parts vinyl silicone oil, 150-350 parts filler, 1-10 parts dimethyl silicone oil, 0.5-2 parts catalyst, and 0.05-0.1 parts inhibitor; Component B, by weight, includes: 20-40 parts vinyl silicone oil, 150-350 parts filler, 20-40 parts crosslinking agent, 0.5-1 part coupling agent, and 1-5 parts color paste; The mass ratio of component A to component B is 1:1.

[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention relates to a two-component silicone thermally conductive and flame-retardant potting compound. The use of low-viscosity vinyl silicone oil effectively improves the leveling properties and reduces the viscosity of the compound. The compound employs a composite of multiple fillers, including silicon carbide, silicon micropowder, alumina, and aluminum hydroxide, to achieve high thermal conductivity and flame retardancy. The crosslinking agent allows for rapid and complete curing of the compound. The addition of a coupling agent to component B further reduces the viscosity of the compound, ensuring excellent flowability even with a high filler content. This allows the potting compound to meet the requirements for potting high-power transformers.

[0006] Furthermore, the viscosity of the vinyl silicone oil is 100–300 mPa·s.

[0007] Furthermore, the filler is composed of silicon carbide, alumina and aluminum hydroxide, or of silica powder, alumina and aluminum hydroxide.

[0008] Furthermore, the weight ratio of silicon carbide, alumina, and aluminum hydroxide is 1:3 to 7:3 to 5; the weight ratio of silicon micropowder, alumina, and aluminum hydroxide is 1:0.5 to 1:0 to 2; and the particle size of alumina is 5 μm, 15 μm, and 40 μm.

[0009] Furthermore, the catalyst is a platinum catalyst.

[0010] Furthermore, the inhibitor is tetramethyltetravinylcyclotetrasiloxane.

[0011] Further, the crosslinking agent is prepared according to the following steps: octamethylcyclotetrasiloxane, hexamethyldisiloxane and methyl hydrogen silicone oil are added to a reaction vessel and stirred and mixed. Then, an acidic catalyst is added under stirring conditions, and the reaction is carried out at 60-80°C for 4-6 hours. After the reaction is completed, the mixture is distilled under reduced pressure at 120-150°C for 4-6 hours, filtered, and the crosslinking agent is obtained.

[0012] Furthermore, the mass ratio of octamethylcyclotetrasiloxane, hexamethyldisiloxane, methyl hydrogen silicone oil and acid catalyst is 20~30:1~5:1~10:1~5; the acid catalyst is acidic clay.

[0013] Furthermore, the coupling agent is one or a mixture of two or more of the following: dodecyltrimethoxysilane, dodecyltriethoxysilane, γ-thiocyanopropyltriethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane.

[0014] On the other hand, the present invention provides a method for preparing a two-component silicone thermally conductive and flame-retardant potting compound, characterized by comprising the following steps: S1. Preparation of crosslinking agent: 20-30 parts of octamethylcyclotetrasiloxane, 1-5 parts of hexamethyldisiloxane and 1-10 parts of methyl hydrogen silicone oil are added to a reaction vessel and stirred. Then, 1-5 parts of acidic catalyst are added under stirring conditions, and the reaction is carried out at 60-80℃ for 4-6 hours. After the reaction is completed, the crosslinking agent is obtained by vacuum distillation at 120-150℃ for 4-6 hours and filtered. Preparation of S2 and A components: Add 60-80 parts of vinyl silicone oil and 1-10 parts of dimethyl silicone oil to reactor A equipped with a constant temperature stirring function, stir for 10 minutes, and after stirring evenly, heat reactor A to 40-50°C, add 75-225 parts of packing material and stir for 10 minutes, then heat reactor A to 80-100°C, add 50-75 parts of packing material and stir for 15 minutes, and finally add 25-50 parts of packing material. Stir under vacuum at 80-100°C for 1.5 hours, cool to room temperature, add catalyst and inhibitor, and then stir for 30 minutes to obtain component A. Preparation of S3 and B components: Add 20-40 parts of vinyl silicone oil, 20-40 parts of crosslinking agent, and 0.5-1 part of coupling agent to reactor B equipped with a constant temperature stirring function, stir for 10 minutes, and after stirring evenly, heat reactor B to 40-50℃, add 75-225 parts of filler and stir for 10 minutes, then heat reactor B to 80-100℃, add 50-75 parts of filler and stir for 15 minutes, and finally add 25-50 parts of filler and 1-5 parts of color paste, and vacuum stir for 2 hours at 80-100℃ to obtain component B; S4. Mix components A and B at a mass ratio of 1:1 under high-speed shear dispersion until homogeneous. Place the mixture in a vacuum drying oven for vacuum degassing for 5 minutes at a vacuum degree of 0.09-0.1 MPa. Then pour the mixture into a mold and cure at room temperature or by heating. Detailed Implementation

[0015] To fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments, but the present invention is not limited thereto. Example 1

[0016] A two-component silicone thermally conductive and flame-retardant potting compound, comprising component A and component B, is prepared by the following method: S1. Preparation of crosslinking agent: 20 parts of octamethylcyclotetrasiloxane, 1 part of hexamethyldisiloxane and 10 parts of methyl hydrogen silicone oil were added to a reaction vessel and stirred. Then, 2 parts of acidic clay were added under stirring conditions, and the mixture was reacted at 80°C for 4 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 120°C for 6 hours and filtered to obtain the crosslinking agent.

[0017] Preparation of S2 and A components: 70 parts of vinyl silicone oil and 4 parts of dimethyl silicone oil were added to reactor A, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor A was heated to 40°C, 125 parts of packing were added and stirred for 10 minutes. Reactor A was then heated to 80°C, 75 parts of packing were added and stirred for 15 minutes. Finally, 50 parts of packing were added and stirred under vacuum at 80°C for 1.5 hours. After cooling to room temperature, 1 part of catalyst and 0.07 parts of inhibitor were added and stirred for 30 minutes to obtain component A.

[0018] Preparation of S3 and B components: 30 parts of vinyl silicone oil, 40 parts of crosslinking agent, and 1 part of coupling agent were added to reactor B, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor B was heated to 40°C, 125 parts of filler were added and stirred for 10 minutes, reactor B was then heated to 80°C, 75 parts of filler were added and stirred for 15 minutes, and finally 50 parts of filler and 4 parts of color paste were added. The mixture was then vacuum stirred at 80°C for 2 hours to obtain component B.

[0019] S4. Mix components A and B at a mass ratio of 1:1 under high-speed shear dispersion until homogeneous. Place the mixture in a vacuum drying oven for vacuum degassing for 5 minutes at a vacuum degree of 0.1 MPa. Then pour the mixture into a mold and heat to cure at a curing temperature of 80℃.

[0020] In this embodiment, the vinyl silicone oil has a viscosity of 100 mPa·s, the filler is silicon carbide, 5 μm alumina, 15 μm aluminum hydroxide, 15 μm alumina, and 40 μm alumina in a weight ratio of 6:7:21:14:8, and the coupling agent is γ-thiocyanopropyltriethoxysilane. Example 2

[0021] A two-component silicone thermally conductive and flame-retardant potting compound, comprising component A and component B, is prepared by the following method: S1. Preparation of crosslinking agent: 25 parts of octamethylcyclotetrasiloxane, 3 parts of hexamethyldisiloxane and 8 parts of methyl hydrogen silicone oil were added to the reaction vessel and stirred. Then, 5 parts of acidic clay were added under stirring conditions, and the reaction was carried out at 70°C for 5 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 130°C for 5 hours and filtered to obtain the crosslinking agent.

[0022] Preparation of S2 and A components: 80 parts of vinyl silicone oil and 1 part of dimethyl silicone oil were added to reactor A, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor A was heated to 50°C, 75 parts of packing were added and stirred for 10 minutes. Then reactor A was heated to 100°C, 50 parts of packing were added and stirred for 15 minutes. Finally, 38 parts of packing were added and stirred under vacuum at 80°C for 1.5 hours. After cooling to room temperature, 2 parts of catalyst and 0.05 parts of inhibitor were added and stirred for 30 minutes to obtain component A.

[0023] Preparation of S3 and B components: 20 parts of vinyl silicone oil, 30 parts of crosslinking agent, and 0.5 parts of coupling agent were added to reactor B, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor B was heated to 50°C, 225 parts of filler were added and stirred for 10 minutes, reactor B was then heated to 100°C, 50 parts of filler were added and stirred for 15 minutes, and finally 25 parts of filler and 1 part of color paste were added. The mixture was then stirred under vacuum at 100°C for 2 hours to obtain component B.

[0024] S4. Mix components A and B at a mass ratio of 1:1 under high-speed shear dispersion until homogeneous. Place the mixture in a vacuum drying oven for vacuum degassing for 5 minutes at a vacuum degree of 0.09 MPa. Then pour the mixture into a mold and heat to cure at a curing temperature of 80℃.

[0025] In this embodiment, the vinyl silicone oil has a viscosity of 200 mPa·s, the filler is silicon carbide, 5 μm alumina, 15 μm aluminum hydroxide, 15 μm alumina and 40 μm alumina in a weight ratio of 2:4:7:4:5, and the coupling agent is a mixture of dodecyltrimethoxysilane and dodecyltriethoxysilane in a mass ratio of 1:1. Example 3

[0026] A two-component silicone thermally conductive and flame-retardant potting compound, comprising component A and component B, is prepared by the following method: S1. Preparation of crosslinking agent: 30 parts of octamethylcyclotetrasiloxane, 5 parts of hexamethyldisiloxane and 2 parts of methyl hydrogen silicone oil were added to a reaction vessel and stirred. Then, 1 part of acidic clay was added under stirring conditions, and the reaction was carried out at 60°C for 6 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 150°C for 4 hours and filtered to obtain the crosslinking agent.

[0027] Preparation of S2 and A components: 60 parts of vinyl silicone oil and 10 parts of dimethyl silicone oil were added to reactor A, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor A was heated to 45°C, 225 parts of packing were added and stirred for 10 minutes. Then reactor A was heated to 90°C, 60 parts of packing were added and stirred for 15 minutes. Finally, 25 parts of packing were added and stirred under vacuum at 100°C for 1.5 hours. After cooling to room temperature, 0.5 parts of catalyst and 0.1 parts of inhibitor were added and stirred for 30 minutes to obtain component A.

[0028] Preparation of S3 and B components: 40 parts of vinyl silicone oil, 20 parts of crosslinking agent, and 0.7 parts of coupling agent were added to reactor B, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor B was heated to 45°C, 75 parts of filler were added and stirred for 10 minutes, reactor B was then heated to 90°C, 60 parts of filler were added and stirred for 15 minutes, and finally 40 parts of filler and 3 parts of color paste were added. The mixture was then stirred under vacuum at 90°C for 2 hours to obtain component B.

[0029] S4. Mix components A and B at a mass ratio of 1:1 under high-speed shear dispersion until homogeneous. Place the mixture in a vacuum drying oven for vacuum degassing for 5 minutes at a vacuum degree of 0.1 MPa. Then pour the mixture into a mold and heat to cure at a curing temperature of 80℃.

[0030] In this embodiment, the vinyl silicone oil has a viscosity of 300 mPa·s, the filler is silicon carbide, 5 μm alumina, 15 μm aluminum hydroxide, 15 μm alumina, and 40 μm alumina in a weight ratio of 5:7:20:3:5, and the coupling agent is phenyltrimethoxysilane. Example 4

[0031] A two-component silicone thermally conductive and flame-retardant potting compound, comprising component A and component B, is prepared by the following method: S1. Preparation of crosslinking agent: The crosslinking agent prepared in Example 1 is used.

[0032] Preparation of S2 and A components: 76 parts of vinyl silicone oil and 4 parts of dimethyl silicone oil were added to reactor A, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor A was heated to 40°C, 122 parts of packing were added and stirred for 10 minutes. Reactor A was then heated to 80°C, 72 parts of packing were added and stirred for 15 minutes. Finally, 48 parts of packing were added and stirred under vacuum at 80°C for 1.5 hours. After cooling to room temperature, 1 part of catalyst and 0.07 parts of inhibitor were added and stirred for 30 minutes to obtain component A.

[0033] Preparation of S3 and B components: 24 parts of vinyl silicone oil, 37 parts of crosslinking agent, and 1 part of coupling agent were added to reactor B, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor B was heated to 40°C, 128 parts of filler were added and stirred for 10 minutes, reactor B was then heated to 80°C, 75 parts of filler were added and stirred for 15 minutes, and finally 50 parts of filler and 3 parts of color paste were added. The mixture was then stirred under vacuum at 80°C for 2 hours to obtain component B.

[0034] S4. Mix components A and B at a mass ratio of 1:1 under high-speed shear dispersion until homogeneous. Place the mixture in a vacuum drying oven for vacuum degassing for 5 minutes at a vacuum degree of 0.09 MPa. Then pour the mixture into a mold and heat to cure at a curing temperature of 80℃.

[0035] In this embodiment, the vinyl silicone oil has a viscosity of 200 mPa·s, the filler is silica powder, 5 μm alumina, 15 μm aluminum hydroxide, 15 μm alumina, and 40 μm alumina in a weight ratio of 7:2:14:1:4, and the coupling agent is diphenyldimethoxysilane. Example 5

[0036] A two-component silicone thermally conductive and flame-retardant potting compound, comprising component A and component B, is prepared by the following method: S1. Preparation of crosslinking agent: The crosslinking agent prepared in Example 1 is used.

[0037] Preparation of S2 and A components: 67 parts of vinyl silicone oil and 4 parts of dimethyl silicone oil were added to reactor A, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor A was heated to 40°C, 210 parts of packing were added and stirred for 10 minutes. Then reactor A was heated to 80°C, 75 parts of packing were added and stirred for 15 minutes. Finally, 50 parts of packing were added and stirred under vacuum at 80°C for 1.5 hours. After cooling to room temperature, 1 part of catalyst and 0.07 parts of inhibitor were added and stirred for 30 minutes to obtain component A.

[0038] Preparation of S3 and B components: 33 parts of vinyl silicone oil, 37 parts of crosslinking agent, and 1 part of coupling agent were added to reactor B, which is equipped with a constant temperature stirring function. After stirring for 10 minutes and until uniform, reactor B was heated to 40°C, 207 parts of filler were added and stirred for 10 minutes, reactor B was then heated to 80°C, 75 parts of filler were added and stirred for 15 minutes, and finally 50 parts of filler and 3 parts of color paste were added. The mixture was then stirred under vacuum at 80°C for 2 hours to obtain component B.

[0039] S4. Mix components A and B at a mass ratio of 1:1 under high-speed shear dispersion until homogeneous. Place the mixture in a vacuum drying oven for vacuum degassing for 5 minutes at a vacuum degree of 0.09 MPa. Then pour the mixture into a mold and heat to cure at a curing temperature of 80℃.

[0040] In this embodiment, the vinyl silicone oil has a viscosity of 200 mPa·s, the fillers are silica powder, 5 μm alumina, 15 μm alumina, and 40 μm alumina in a weight ratio of 8:2:1:3, and the coupling agent is γ-thiocyanopropyltriethoxysilane. Comparative Example 1

[0041] In this comparative example, the viscosity of the vinyl silicone oil is 500 mPa·s, and the rest of the preparation methods and steps are the same as in Example 4. Comparative Example 2

[0042] In this comparative example, the coupling agent was 3-glycidyl etheroxypropyltrimethoxysilane, and the rest of the preparation methods and steps were the same as in Example 2. Comparative Example 3

[0043] In this comparative example, the filler is boron nitride, and the rest of the preparation methods and steps are the same as in Example 3. Comparative Example 4

[0044] In this comparative example, the filler was silicon carbide, 5μm alumina, 15μm aluminum hydroxide, 15μm alumina, and 40μm alumina in a weight ratio of 4:2:28:3:5. The remaining preparation methods and steps were the same as in Example 3.

[0045] The potting compounds prepared in the examples and comparative examples were tested for thermal conductivity, flame retardancy rating and viscosity. The test results are shown in Table 1.

[0046] Table 1. Test results of potting compounds prepared in the examples and comparative examples.

[0047] As can be seen from Table 1, the two-component silicone thermally conductive and flame-retardant potting compounds prepared in Examples 1 to 5 have high thermal conductivity and good leveling properties. The improved filler ratio enhances the thermal conductivity and flame retardant rating of the potting compounds, enabling them to meet the potting requirements of high-power transformers.

[0048] Finally, it should be noted that the above-listed embodiments are merely preferred embodiments of the present invention. Of course, those skilled in the art can make modifications and variations to the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered as being within the protection scope of the present invention.

Claims

1. A two-component silicone thermally conductive and flame-retardant potting compound, comprising component A and component B, characterized in that: Component A, by weight, comprises: 60-80 parts vinyl silicone oil, 150-350 parts filler, 1-10 parts dimethyl silicone oil, 0.5-2 parts catalyst, and 0.05-0.1 parts inhibitor; Component B, by weight, comprises: 20-40 parts vinyl silicone oil, 150-350 parts filler, 20-40 parts crosslinking agent, 0.5-1 part coupling agent, and 1-5 parts color paste; wherein the mass ratio of component A to component B is 1:

1. The filler is composed of silicon carbide, 5μm aluminum oxide, 15μm aluminum hydroxide, 15μm aluminum oxide, and 40μm aluminum oxide in a weight ratio of 2:4:7:4:

5. The crosslinking agent is prepared according to the following steps: Octamethylcyclotetrasiloxane, hexamethyldisiloxane and methyl hydrogen silicone oil are added to a reaction vessel and stirred and mixed. Then, an acidic catalyst is added under stirring conditions, and the reaction is carried out at 60-80°C for 4-6 hours. After the reaction is completed, the crosslinking agent is obtained by vacuum distillation at 120-150°C for 4-6 hours and then filtered. The mass ratio of octamethylcyclotetrasiloxane, hexamethyldisiloxane, methyl hydrogen silicone oil and acid catalyst is 20~30:1~5:1~10:1~5; the acid catalyst is acidic clay. The coupling agent is one or a mixture of two or more of the following: dodecyltrimethoxysilane, dodecyltriethoxysilane, γ-thiocyanopropyltriethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane. The preparation method of the two-component silicone thermally conductive and flame-retardant potting compound includes the following steps: S1. Preparation of crosslinking agent: 20-30 parts of octamethylcyclotetrasiloxane, 1-5 parts of hexamethyldisiloxane and 1-10 parts of methyl hydrogen silicone oil are added to a reaction vessel and stirred. Then, 1-5 parts of acidic catalyst are added under stirring conditions, and the reaction is carried out at 60-80℃ for 4-6 hours. After the reaction is completed, the crosslinking agent is obtained by vacuum distillation at 120-150℃ for 4-6 hours and filtered. Preparation of S2 and A components: Add 60-80 parts of vinyl silicone oil and 1-10 parts of dimethyl silicone oil to reactor A equipped with a constant temperature stirring function, stir for 10 minutes, and after stirring evenly, heat reactor A to 40-50°C, add 75-225 parts of packing material and stir for 10 minutes, then heat reactor A to 80-100°C, add 50-75 parts of packing material and stir for 15 minutes, and finally add 25-50 parts of packing material. Stir under vacuum at 80-100°C for 1.5 hours, cool to room temperature, add catalyst and inhibitor, and then stir for 30 minutes to obtain component A. Preparation of S3 and B components: Add 20-40 parts of vinyl silicone oil, 20-40 parts of crosslinking agent, and 0.5-1 part of coupling agent to reactor B equipped with a constant temperature stirring function, stir for 10 minutes, and after stirring evenly, heat reactor B to 40-50℃, add 75-225 parts of filler and stir for 10 minutes, then heat reactor B to 80-100℃, add 50-75 parts of filler and stir for 15 minutes, and finally add 25-50 parts of filler and 1-5 parts of color paste, and vacuum stir for 2 hours at 80-100℃ to obtain component B; S4. Mix components A and B at a mass ratio of 1:1 under high-speed shear dispersion until homogeneous. Place the mixture in a vacuum drying oven for vacuum degassing for 5 minutes at a vacuum degree of 0.09-0.1 MPa. Then pour the mixture into a mold and cure at room temperature or by heating.

2. The two-component silicone thermally conductive and flame-retardant potting compound according to claim 1, characterized in that: The viscosity of vinyl silicone oil is 100–300 mPa·s.

3. The two-component silicone thermally conductive and flame-retardant potting compound according to claim 1, characterized in that: The catalyst is a platinum catalyst.

4. The two-component silicone thermally conductive and flame-retardant potting compound according to claim 1, characterized in that: The inhibitor is tetramethyltetravinylcyclotetrasiloxane.

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