Organic silicon pouring sealant as well as preparation method and application thereof

Abstract

The invention discloses an organic silicon pouring sealant as well as a preparation method and application thereof, and belongs to the technical field of organic materials. The organic silicon pouring sealant provided by the invention comprises a component A and a component B, the component A comprises the following raw materials: first vinyl silicone oil, a first silane coupling agent, first powder, first hollow glass beads and a catalyst; the component B comprises the following raw materials: second vinyl silicone oil, end hydrogen-containing silicone oil, side hydrogen-containing silicone oil, a second silane coupling agent, second powder, second hollow glass beads and an inhibitor; the first powder and the second powder respectively and independently comprise aluminum hydroxide and a group consisting of magnesium hydroxide and / or boron nitride. Aluminum hydroxide and compounding of aluminum hydroxide with magnesium hydroxide and / or boron nitride are adopted, the obtained powder is combined with the hollow glass beads, surface modification is conducted through the silane coupling agent, the heat conduction performance of the organic silicon pouring sealant can be effectively improved, and meanwhile the characteristics of low viscosity, low density and high flame retardance are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic materials, and in particular relates to an organic silicon potting compound and a preparation method and application thereof. Background Art

[0002] The rapid development of new energy vehicles and low-altitude aircraft is placing higher demands on potting materials for electronic components. While traditional silicone potting compounds offer excellent insulation, high- and low-temperature resistance, and chemical stability, they suffer from high density and poor thermal conductivity, failing to meet the urgent demand for low-density, high-thermal conductivity potting compounds in new energy vehicles and low-altitude aircraft.

[0003] To improve the thermal conductivity of silicone potting compounds, existing technologies typically add large amounts of inorganic fillers, such as SiO2 and Al2O3, to the potting compound. However, while this approach improves thermal conductivity, it also significantly increases the density of the potting compound, making it unable to meet lightweighting requirements. On the other hand, while lightweight fillers such as hollow glass microspheres have also been used to reduce density, these fillers themselves have poor thermal conductivity and, after addition, increase the viscosity of the potting compound. Consequently, they cannot meet the high thermal conductivity, low density, and low viscosity requirements of potting compounds for new energy vehicles and low-altitude aircraft.

[0004] To address the high density and poor thermal conductivity of existing silicone potting compounds, existing technology discloses a two-component silicone potting compound with high thermal conductivity and low dielectric constant, comprising components A and B. Component A includes filler, powder, vinyl silicone oil, a crosslinker, and an inhibitor; component B includes filler, powder, vinyl silicone oil, and a catalyst. This technology optimizes the ratio of powdered silicon micropowder, hollow glass microspheres, and spherical boron nitride to achieve a potting compound with a thermal conductivity exceeding 1.88 W / m·K. While this technology achieves a high thermal conductivity, its density still falls short of technical requirements. Furthermore, spherical boron nitride is expensive, making it difficult to use in large quantities in potting compounds for new energy vehicles.

[0005] There is also a technology that discloses a low-density, high-thermal-conductivity, flame-retardant silicone potting compound for power vehicle batteries. The compound thermal conductive powder is obtained by using silicon carbide, boron nitride, spherical alumina, and spherical aluminum powder, and then combined with hollow glass microspheres and / or hollow silica microspheres to achieve the effect of low density and high thermal conductivity. However, the cost required for this technology is too high and it is not suitable for large-scale potting of new energy vehicles and low-altitude aircraft. At the same time, the large amount of aluminum powder added in this technology will seriously affect the electrical breakdown strength of the potting compound. Summary of the Invention

[0006] In order to overcome at least one of the problems existing in the above-mentioned prior art, one of the objectives of the present invention is to provide a silicone potting compound having low density, low viscosity, high thermal conductivity and high flame retardancy.

[0007] A second object of the present invention is to provide a method for preparing the above-mentioned organosilicon potting compound.

[0008] A third object of the present invention is to provide an application of the above-mentioned organosilicon potting adhesive.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] The first aspect of the present invention provides an organic silicone potting compound, comprising a component A and a component B; the component A comprises the following raw materials: a first vinyl silicone oil, a first silane coupling agent, a first powder, a first hollow glass microsphere, and a catalyst; the component B comprises the following raw materials: a second vinyl silicone oil, a terminal hydrogen-containing silicone oil, a side hydrogen-containing silicone oil, a second silane coupling agent, a second powder, a second hollow glass microsphere, and an inhibitor; the first powder and the second powder each independently comprise aluminum hydroxide, and a group consisting of magnesium hydroxide and / or boron nitride.

[0011] In the present invention, the first vinyl silicone oil is the same as or different from the second vinyl silicone oil; the first silane coupling agent is the same as or different from the second silane coupling agent; the first powder is the same as or different from the second powder; and the first hollow glass microspheres are the same as or different from the second hollow glass microspheres.

[0012] Preferably, the first powder and the second powder each independently comprise the following composition in parts by mass: 50-120 parts of aluminum hydroxide, 0-60 parts of magnesium hydroxide, and 0-10 parts of boron nitride; and the parts by mass of magnesium hydroxide and boron nitride are not both zero. Further preferably, the first powder and the second powder each independently comprise the following composition in parts by mass: 60-100 parts of aluminum hydroxide, 0-50 parts of magnesium hydroxide, and 0-8 parts of boron nitride; and the parts by mass of magnesium hydroxide and boron nitride are not both zero.

[0013] In some embodiments of the present invention, the first powder and the second powder each independently comprise the following composition in parts by mass: 50-120 parts of aluminum hydroxide and 5-60 parts of magnesium hydroxide; or, the first powder and the second powder each independently comprise the following composition in parts by mass: 50-120 parts of aluminum hydroxide and 2-10 parts of boron nitride; or, the first powder and the second powder each independently comprise the following composition in parts by mass: 50-120 parts of aluminum hydroxide, 5-60 parts of magnesium hydroxide, and 2-10 parts of boron nitride. In some specific embodiments of the present invention, the first powder and the second powder each independently comprise the following composition in parts by mass: 50-120 parts of aluminum hydroxide and 5-60 parts of magnesium hydroxide. In some more specific embodiments of the present invention, the first powder and the second powder each independently comprise the following composition in parts by mass: 60-100 parts of aluminum hydroxide and 10-50 parts of magnesium hydroxide.

[0014] Compared with boron nitride, the raw material cost of aluminum hydroxide and magnesium hydroxide is lower, which can effectively reduce the preparation cost and facilitate large-scale production. The combination of these two materials can also achieve good modification effects, effectively improving the thermal conductivity of the potting compound while ensuring that the potting compound has low viscosity.

[0015] Preferably, the average particle size of the first powder and the average particle size of the second powder are each independently 1 to 70 μm; more preferably 2 to 50 μm; for example, they can be any value among 2 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm or 50 μm, or a range between any two of them.

[0016] Preferably, the first powder and the second powder each independently include first particles and second particles; the average particle size of the first particles is 1 to 10 μm; the average particle size of the second particles is 15 to 70 μm; further preferably, the average particle size of the first particles is 1 to 5 μm; the average particle size of the second particles is 15 to 30 μm; for example, the average particle size of the first particles can be any value of 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, or a range value between any two of them; the average particle size of the second particles can be any value of 15 μm, 18 μm, 20 μm, 25 μm or 30 μm, or a range value between any two of them.

[0017] The compounding of powder materials with different particle sizes can significantly improve the anti-settling performance of the potting compound, form a better heat conduction channel, and improve the thermal conductivity of the potting compound.

[0018] Preferably, the purity of the magnesium hydroxide is ≥98%; for example, it can be any value among 98%, 98.5%, 99%, 99.5% or 100%, or a range value between any two of them.

[0019] The use of high-purity magnesium hydroxide can avoid the influence of impurities such as calcium carbonate and silicon powder on the performance of the potting compound, ensure the formation of an excellent heat conduction channel, and obtain high thermal conductivity and low viscosity.

[0020] Preferably, the true density of the first hollow glass microsphere and the true density of the second hollow glass microsphere are independently 0.15 to 0.25 g / cm 3 ; More preferably 0.18 to 0.22 g / cm 3 .

[0021] True density refers to the actual mass of solid matter per unit volume when the material is in an absolutely dense state, that is, the density after removing the gaps between particles.

[0022] Preferably, the average particle size of the first hollow glass microspheres and the average particle size of the second hollow glass microspheres are each independently 40 to 100 μm; more preferably 50 to 90 μm.

[0023] Adding hollow glass microspheres can further improve the dielectric properties of the potting compound. However, there is a vacuum and rarefied gas inside the hollow glass microspheres, which will affect the thermal conductivity to a certain extent. By optimizing the density and particle size of the hollow glass microspheres, it is beneficial to reduce the density of the potting compound while maintaining a high thermal conductivity.

[0024] Preferably, the viscosity of the first vinyl silicone oil at 25° C. and the viscosity of the second vinyl silicone oil at 25° C. are each independently 50 to 500 mPa·s; more preferably, they are each independently 50 to 200 mPa·s.

[0025] Preferably, the vinyl content of the first vinyl silicone oil and the vinyl content of the second vinyl silicone oil are each independently 0.4 to 2 wt %; further preferably, each independently 0.5 to 2 wt %.

[0026] Preferably, the chemical formula of the first vinyl silicone oil and the chemical formula of the second vinyl silicone oil are each independently represented by the following formula (II): In formula (II), D is 20 to 100.

[0027] In the present invention, in formula (II), D is an integer.

[0028] Preferably, the viscosity of the hydrogen-terminated silicone oil at 25° C. is 10 to 1000 mPa·s; more preferably, it is 100 to 600 mPa·s.

[0029] Preferably, the hydrogen content of the hydrogen-terminated silicone oil is 0.01 to 0.18 wt %, and more preferably 0.015 to 0.05 wt %.

[0030] Preferably, the chemical formula of the hydrogen-terminated silicone oil is as shown in the following formula (III): In formula (III), D is 20 to 300.

[0031] In the present invention, in formula (III), D is an integer.

[0032] Preferably, the viscosity of the side hydrogenated silicone oil at 25° C. is 20 to 200 mPa·s; more preferably, it is 20 to 110 mPa·s.

[0033] Preferably, the hydrogen content of the side hydrogenated silicone oil is 0.08-0.6 wt %, more preferably 0.1-0.3 wt %.

[0034] Preferably, the chemical formula of the side hydrogenated silicone oil is as shown in the following formula (IV): In formula (IV), D is 20 to 80, and D' is 5 to 10.

[0035] In the present invention, in formula (IV), D and D' are both integers.

[0036] Preferably, the catalyst is selected from a platinum catalyst; further preferably, the platinum catalyst includes at least one of a divinyltetramethyldisiloxane platinum complex, a divinyloctamethyltetrasiloxane platinum complex or a chloroplatinic acid alcohol solution.

[0037] Preferably, the inhibitor comprises at least one of acetylene cyclohexanol, methylbutynol, tetramethyldivinyldisiloxane or trimethyl-dodecynol; further preferably, the inhibitor comprises at least one of acetylene cyclohexanol, methylbutynol or trimethyl-dodecynol.

[0038] Adding inhibitors to silicone potting compound can control its reaction speed during curing, making it have excellent operability during potting.

[0039] Preferably, the first silane coupling agent and the second silane coupling agent each independently include a methoxy mono-terminated silane coupling agent, an ethoxy mono-terminated silane coupling agent or a combination thereof; further preferably, the first silane coupling agent and the second silane coupling agent each independently selected from a methoxy mono-terminated silane coupling agent.

[0040] Preferably, the chemical formula of the first silane coupling agent and the chemical formula of the second silane coupling agent are independently represented by the following formula (I): In formula (I), R1 is a C1-C5 alkyl group; R2 is a C1-C5 alkyl group; x is 1-12; n is 10-60; and m is 1-3.

[0041] In the present invention, in formula (I), x, n, and m are all integers.

[0042] Preferably, in formula (I), R1 is methyl or ethyl; further preferably, in formula (I), R1 is methyl.

[0043] Preferably, in formula (I), R2 is methyl or ethyl; further preferably, in formula (I), R2 is methyl.

[0044] Preferably, the component A comprises the following raw materials in parts by mass: 20 to 50 parts of a first vinyl silicone oil, 0.5 to 5 parts of a first silane coupling agent, 80 to 150 parts of a first powder, 1 to 10 parts of a first hollow glass microsphere, and 0.1 to 1 part of a catalyst; the component B comprises the following raw materials in parts by mass: 10 to 30 parts of a second vinyl silicone oil, 5 to 25 parts of end-hydrogenated silicone oil, 0.5 to 5 parts of side-hydrogenated silicone oil, 0.5 to 5 parts of a second silane coupling agent, 80 to 150 parts of a second powder, 1 to 10 parts of a second hollow glass microsphere, and 0.01 to 0.5 parts of an inhibitor; the mass ratio of the component A to the component B is 1:(0.5 to 1.5).

[0045] Further preferably, the A component comprises the following raw materials in parts by mass: 30 to 40 parts of a first vinyl silicone oil, 1 to 2 parts of a first silane coupling agent, 100 to 120 parts of a first powder, 3 to 6 parts of a first hollow glass microsphere, and 0.3 to 0.5 parts of a catalyst; the B component comprises the following raw materials in parts by mass: 15 to 25 parts of a second vinyl silicone oil, 8 to 15 parts of end-hydrogenated silicone oil, 1 to 3 parts of side-hydrogenated silicone oil, 1 to 2 parts of a second silane coupling agent, 100 to 120 parts of a second powder, 3 to 6 parts of a second hollow glass microsphere, and 0.05 to 0.2 parts of an inhibitor; the mass ratio of the A component to the B component is 1:(0.8 to 1.2).

[0046] In some embodiments of the present invention, the A component comprises the following raw materials in parts by mass: 20 to 50 parts of a first vinyl silicone oil, 0.5 to 5 parts of a first silane coupling agent, 50 to 120 parts of aluminum hydroxide, 0 to 60 parts of magnesium hydroxide, 0 to 10 parts of boron nitride, 1 to 10 parts of a first hollow glass microsphere, and 0.1 to 1 part of a catalyst; and in the A component, the mass fractions of magnesium hydroxide and boron nitride are not zero at the same time; the B component comprises the following raw materials in parts by mass: 10 to 30 parts of a second vinyl silicone oil, 5 to 25 parts of end-containing hydrogen silicone oil, 0.5 to 5 parts of side-containing hydrogen silicone oil, 0.5 to 5 parts of a second silane coupling agent, 50 to 120 parts of aluminum hydroxide, 0 to 60 parts of magnesium hydroxide, 0 to 10 parts of boron nitride, 1 to 10 parts of a second hollow glass microsphere, and 0.01 to 0.5 parts of an inhibitor; and in the B component, the mass fractions of magnesium hydroxide and boron nitride are not zero at the same time; the mass ratio of the A component to the B component is 1:(0.5 to 1.5).

[0047] In some specific embodiments of the present invention, the component A includes the following raw materials in parts by mass: 30-40 parts of a first vinyl silicone oil, 1-2 parts of a first silane coupling agent, 50-120 parts of aluminum hydroxide, 5-60 parts of magnesium hydroxide, 3-6 parts of a first hollow glass microsphere, and 0.3-0.5 parts of a catalyst; the component B includes the following raw materials in parts by mass: 15-25 parts of a second vinyl silicone oil, 8-15 parts of end-hydrogenated silicone oil, 1-3 parts of side-hydrogenated silicone oil, 1-2 parts of a second silane coupling agent, 50-120 parts of aluminum hydroxide, 5-60 parts of magnesium hydroxide, 3-6 parts of a second hollow glass microsphere, and 0.05-0.2 parts of an inhibitor; the mass ratio of the component A to the component B is 1:(0.8-1.2).

[0048] In some embodiments of the present invention, the raw materials of component A further include a color paste, more specifically a carbon black paste. The mass percentage of the color paste in the raw materials of component A may be 0.01% to 0.5%, more specifically 0.05% to 0.2%.

[0049] The second aspect of the present invention provides a method for preparing the silicone potting compound according to the first aspect of the present invention, comprising the following steps: mixing a first vinyl silicone oil with a first silane coupling agent, then adding a first powder and a first hollow glass microsphere and mixing them, and finally adding a catalyst and mixing them to obtain component A; mixing a second vinyl silicone oil with a second silane coupling agent, then adding a second powder and a second hollow glass microsphere and mixing them, and finally adding end hydrogen-containing silicone oil, side hydrogen-containing silicone oil and an inhibitor and mixing them to obtain component B.

[0050] The third aspect of the present invention provides a use of the organosilicon potting compound described in the first aspect of the present invention in the preparation of electronic components.

[0051] In some embodiments of the present invention, the electronic components include electronic components in automobiles, aviation equipment, or electrical equipment.

[0052] The beneficial effects of the present invention are as follows: the present invention uses aluminum hydroxide and its compound with magnesium hydroxide and / or boron nitride to obtain powder combined with hollow glass microspheres, and performs surface modification with a silane coupling agent, which can effectively improve the thermal conductivity of the silicone potting compound, while achieving low viscosity, low density and high flame retardancy. The silicone potting compound has a wide range of applications in the preparation of electronic components, and can be particularly widely used in the preparation of electronic components in automobiles, aviation equipment or electrical equipment.

[0053] Specifically, compared with the prior art, the present invention has the following advantages:

[0054] 1. The thermal conductivity of magnesium hydroxide is higher than that of aluminum hydroxide, but magnesium hydroxide is easily hydrolyzed and has a large number of hydroxyl groups on the surface. Direct addition will cause the viscosity of the potting compound to be too high. The present invention compounds aluminum hydroxide and magnesium hydroxide and then uses a silane coupling agent to perform good surface modification on the powder, which can effectively increase the hydrophobicity of the powder and its compatibility with silicone oil.

[0055] 2. The present invention can minimize the impact on thermal conductivity while maximizing the reduction in density by compounding aluminum hydroxide, magnesium hydroxide, boron nitride, hollow glass microspheres, etc., and ultimately achieve viscosity ≤ 4000 mPa·s, thermal conductivity ≥ 0.8 W / m·K, and density ≤ 1.4 g / cm 3 The low-density and high-thermal-conductivity silicone potting compound can meet the performance requirements of automobiles, aviation equipment or electrical equipment for potting compounds, especially the low-density and high-thermal-conductivity requirements of new energy vehicles and low-altitude aircraft for potting compounds. DETAILED DESCRIPTION

[0056] The content of the present invention is further described in detail below through specific examples. It should be understood that the following examples are only used to further illustrate the present invention and cannot be interpreted as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0057] It should be noted that in the following examples and comparative examples, some of the raw materials used are as follows:

[0058] (1) Silane coupling agent: In formula (I), R1 is a methyl group or an ethyl group; R2 is a methyl group; x is 1 to 12; n is 10 to 60; and m is 1 to 3, wherein x, n, and m are all integers.

[0059] (2) Vinyl silicone oil: viscosity at 25°C is 50-200 mPa·s; vinyl content is 0.5 wt%-2 wt%; the specific chemical formula is In formula (II), D is 20 to 100, and D is an integer.

[0060] (3) Hydrogenated silicone oil: viscosity at 25°C is 100-600 mPa·s; hydrogen content is 0.015-0.05 wt%; the specific chemical formula is In formula (III), D is 20 to 300, and D is an integer.

[0061] (4) Side hydrogenated silicone oil: viscosity at 25°C is 20-110 mPa·s; hydrogen content is 0.1-0.3 wt%; the specific chemical formula is

[0062] In formula (IV), D is 20 to 80, and D' is 5 to 10, and both D and D' are integers.

[0063] (5) Aluminum hydroxide: It has two particle sizes, with average particle sizes of 18 μm and 2 μm respectively, and is commonly available in the market.

[0064] (6) Magnesium hydroxide: high-purity magnesium hydroxide, purity ≥98%, two particle sizes, average particle sizes of 18 μm and 2 μm respectively; ore-process magnesium hydroxide, purity <98%, two particle sizes, average particle sizes of 18 μm and 2 μm respectively; both are commercially available.

[0065] (7) Hollow glass microspheres: true density is 0..18~0.22g / cm 3 ; Particle size D 50 55μm, D 90 90 μm; purchased from Zhengzhou Shenglait Hollow Microsphere New Materials Co., Ltd.

[0066] (8) Boron nitride PBN40: particle size D50 is 45 μm; purchased from Ya'an Baitu High-tech Materials Co., Ltd.

[0067] (9) Methyl silicone oil, silicon micropowder, aluminum oxide Al2O3, carbon black slurry, Pt catalyst (Heraeus 3000 ppm Karestedt dilution), and inhibitor acetylene cyclohexanol are all commercially available.

[0068] In the following examples and comparative examples, room temperature refers to 25±5°C.

[0069] Example 1

[0070] A silicone potting compound is composed of component A and component B, wherein the mass ratio of component A to component B is 1:1. The specific preparation steps are as follows:

[0071] Preparation of component A:

[0072] Accurately weigh 3.40 kg of vinyl silicone oil with a viscosity of 50 mPa·s and place it in a double planetary stirred tank equipped with a heating and vacuum system. Add 0.15 kg of silane coupling agent and heat to 100°C. Add 7.20 kg of 18 μm aluminum hydroxide, 1.50 kg of 2 μm aluminum hydroxide, 1.50 kg of 2 μm magnesium hydroxide, and 0.425 kg of hollow glass microspheres in batches. Set the stirring speed to 60 rpm and 1500 rpm for 60 minutes. Turn off the heating and cool to below 45°C with circulating water. Add 0.04 kg of Pt catalyst and 0.01 kg of carbon black slurry, stir at 60 rpm and 1500 rpm, and stir under vacuum at room temperature for 30 minutes to obtain component A.

[0073] Preparation of component B:

[0074] Accurately weigh 1.90 kg of vinyl silicone oil with a viscosity of 100 mPa·s and place it in a dual planetary stirred tank equipped with a heating and vacuum system. Add 0.15 kg of silane coupling agent and heat to 100°C. Add 7.20 kg of 18 μm aluminum hydroxide, 3.00 kg of 2 μm high-purity magnesium hydroxide, and 0.425 kg of hollow glass microspheres in batches. Set the stirring speed to 60 rpm and 1500 rpm for 60 minutes. Turn off the heat and cool to below 45°C with circulating water. Add 1.10 kg of chain extender-terminated hydrogenated silicone oil, 0.20 kg of crosslinker-terminated hydrogenated silicone oil, and 0.01 kg of acetylene cyclohexanol as an inhibitor. Stir at 60 rpm and 1500 rpm. Stir under vacuum at room temperature for 30 minutes to obtain component B.

[0075] When in use, mix component A and component B in a mass ratio of 1:1 at 25-30°C, stir evenly, degas under a negative pressure of 0.1 MPa, and then solidify to obtain the product.

[0076] Examples 2 to 3 and Comparative Examples 1 to 8

[0077] A silicone potting compound differs from Example 1 in the raw materials and amounts used. The raw materials and amounts used in Examples 2-3 and Comparative Examples 1-8 are listed in Table 1. The preparation method is the same as that in Example 1. The order of mixing boron nitride, silicon micropowder, and aluminum oxide is the same as the order of mixing aluminum hydroxide, and the order of mixing methyl silicone oil is the same as the order of mixing silane coupling agent.

[0078] Performance Testing

[0079] 1) Density test (g / cm 3 ):GB / T 533-2008 “Vulcanized rubber - Determination of density” is used to test the density of the cured product.

[0080] 2) Hardness Test (Shore A): Weigh components A and B in a 1:1 weight ratio (±5% tolerance allowed). Manually stir for 2 minutes and evacuate for 5 minutes. Curing at the specified temperature is then performed using a Shore A hardness tester. For details, refer to GB / T 2411-2008.

[0081] 3) Thermal Conductivity Test (W / m·K): Hotdisk, reference standard ISO 22007-2024, 50g each of components A and B, tested after vacuum curing, test parameters: 10s and 80mW; sample size: 3 pieces.

[0082] 4) Viscosity Test (mPa·s): Components A and B were weighed in a weight ratio of 1:1 (±5% deviation allowed), manually stirred for 1–3 minutes, and vacuumed for 1–3 minutes. Viscosity was then measured using a Brookfield viscometer with a No. 4 rotor at 20 rpm according to the method specified in GB / T 2794-2022. The viscosities of components A and B were recorded as Viscosity A and Viscosity B, respectively.

[0083] 5) Breakdown Voltage Test (kV / mm): Mix components A and B in a weight ratio of 1:1 within 3 minutes. Squeeze into a dedicated mold and lay flat to form a test piece with a thickness of (2.0±0.2) mm. Cure under the specified curing conditions (85°C / 30 minutes). After curing, cut the test piece into 40×40 mm pieces using a cutter and test using a voltage breakdown tester. Reference standard: GB / T1695-2005.

[0084] 6) Flame Retardancy Test: Mix components A and B in a 1:1 weight ratio within 3 minutes. Squeeze into a dedicated mold and lay flat to form a test piece with a thickness of (3.0±0.2) mm. Cure under the specified curing conditions (85°C / 30 minutes). After curing, cut the test piece into 127 mm long x 12.7 mm wide test pieces for flame retardancy testing. Reference standard: UL 94-2023.

[0085] The test results are recorded in Table 1.

[0086] Table 1 Raw materials, dosages and performance test results of Examples 1 to 3 and Comparative Examples 1 to 8 (dosage unit: 100 g)

[0087]

[0088]

[0089]

[0090] The following conclusions can be drawn from the analysis of Table 1:

[0091] It can be seen from the test results of Examples 1 to 2 and Comparative Example 1 that after using high-purity magnesium hydroxide to replace part of the aluminum hydroxide in Examples 1 to 2, the thermal conductivity of the glue is increased from 0.73 W / m·K to above 0.8 W / m·K through sufficient powder surface modification; combined with Example 3, it can be found that by combining aluminum hydroxide with boron nitride, the thermal conductivity can also be increased to above 0.8 W / m·K, and the viscosity of the potting glue is lower than that of Examples 1 to 2. However, the current average price of boron nitride on the market is above 500 yuan / kg. After using boron nitride, the overall cost increases by 15 yuan / kg, and this solution has low market competitiveness.

[0092] By comparing Example 1 with Comparative Examples 1 to 2, it can be seen that with the addition of high-purity magnesium hydroxide, the thermal conductivity of the potting compound increases, but with the increase in the amount of high-purity magnesium hydroxide, the overall viscosity of the potting compound also increases sharply, resulting in poor fluidity of the potting compound and failure to meet the requirements of small gap potting. Therefore, controlling the amount of magnesium hydroxide within a certain range can achieve better modification effects.

[0093] By comparing Comparative Examples 3 to 5, it can be seen that if ore-based magnesium hydroxide is used instead of high-purity synthetic magnesium hydroxide, the viscosity of the glue increases faster, while the thermal conductivity coefficient fails to be improved. The main reason is that the purity of ore-based magnesium hydroxide is not high, and it contains a large amount of impurities such as calcium carbonate and silicon powder, which affect the establishment of the heat conduction channel.

[0094] By comparing Example 1 with Comparative Example 6, it can be seen that after the silane coupling agent in Comparative Example 6 is replaced with methyl silicone oil of the same viscosity, the thermal conductive powder fails to obtain effective surface modification, has poor compatibility with the base silicone oil, and the viscosity of the prepared potting compound is too high, which cannot meet the potting requirements at all.

[0095] By comparing Comparative Examples 1 and 7-8, it can be seen that Comparative Examples 7-8 use silicon powder and alumina instead of aluminum hydroxide, the density and thermal conductivity are poor, and the flame retardant grade is only UL94 V2, and the comprehensive performance is not as good as that of aluminum hydroxide.

[0096] In the embodiment of the present invention, aluminum hydroxide, magnesium hydroxide, boron nitride, hollow glass microspheres, etc. are compounded to minimize the effect on thermal conductivity while maximizing density reduction, and ultimately obtain viscosity ≤ 4000 mPa·s, thermal conductivity ≥ 0.8 W / m·K, and density ≤ 1.4 g / cm 3The low-density and high-thermal-conductivity silicone potting compound can meet the performance requirements of automobiles, aviation equipment or electrical equipment for potting compounds, especially the low-density and high-thermal-conductivity requirements of new energy vehicles and low-altitude aircraft for potting compounds.

[0097] The thermal conductivity of magnesium hydroxide is higher than that of aluminum hydroxide, but magnesium hydroxide is easily hydrolyzed and has a large number of hydroxyl groups on its surface. Direct addition will cause the viscosity of the potting compound to be too high. In the embodiment of the present invention, by compounding aluminum hydroxide and magnesium hydroxide and then using a silane coupling agent to perform good surface modification on the powder, the hydrophobic properties of the powder and its compatibility with silicone oil can be effectively increased.

[0098] In summary, the present invention uses aluminum hydroxide and its compound with magnesium hydroxide and / or boron nitride to obtain a powder combined with hollow glass microspheres, and then performs surface modification with a silane coupling agent, which can effectively improve the thermal conductivity of the silicone potting compound while achieving low viscosity, low density and high flame retardancy. The silicone potting compound has a wide range of applications in the preparation of electronic components, and can be particularly widely used in the preparation of electronic components in automobiles, aviation equipment or electrical equipment.

Claims

1. A silicone potting compound, characterized in that: The invention comprises component A and component B; component A comprises the following raw materials: a first vinyl silicone oil, a first silane coupling agent, a first powder, a first hollow glass microsphere, and a catalyst; component B comprises the following raw materials: a second vinyl silicone oil, a terminal hydrogen-containing silicone oil, a side hydrogen-containing silicone oil, a second silane coupling agent, a second powder, a second hollow glass microsphere, and an inhibitor; the first powder and the second powder each independently comprise aluminum hydroxide, and a group consisting of magnesium hydroxide and / or boron nitride.

2. The organic silicone potting compound according to claim 1, characterized in that: The first powder and the second powder each independently comprise the following components in parts by mass: 50 to 120 parts of aluminum hydroxide, 0 to 60 parts of magnesium hydroxide, and 0 to 10 parts of boron nitride; and the parts by mass of magnesium hydroxide and boron nitride are not both zero.

3. The organic silicone potting compound according to claim 1, characterized in that: The average particle size of the first powder and the average particle size of the second powder are each independently 1 to 70 μm.

4. The organic silicone potting compound according to claim 1, characterized in that: The first powder and the second powder each independently include first particles and second particles; the average particle size of the first particles is 1 to 10 μm; and the average particle size of the second particles is 15 to 70 μm.

5. The organic silicone potting compound according to claim 1, characterized in that: The purity of the magnesium hydroxide is ≥98%; And / or, the true density of the first hollow glass microsphere and the true density of the second hollow glass microsphere are each independently 0.15 to 0.25 g / cm 3 ; And / or, the average particle size of the first hollow glass microspheres and the average particle size of the second hollow glass microspheres are each independently 40 to 100 μm.

6. The organic silicone potting compound according to claim 1, characterized in that: The viscosity of the first vinyl silicone oil at 25° C. and the viscosity of the second vinyl silicone oil at 25° C. are each independently 50 to 500 mPa·s; and / or, the vinyl content of the first vinyl silicone oil and the vinyl content of the second vinyl silicone oil are each independently 0.4 to 2 wt%; and / or, the viscosity of the hydrogen-terminated silicone oil at 25° C. is 10 to 1000 mPa·s; and / or, the hydrogen content of the hydrogen-terminated silicone oil is 0.01 to 0.18 wt%; and / or, the viscosity of the side hydrogenated silicone oil at 25° C. is 20 to 200 mPa·s; And / or, the hydrogen content of the side hydrogenated silicone oil is 0.08-0.6 wt%; And / or, the catalyst is selected from a platinum catalyst; the platinum catalyst includes at least one of a divinyltetramethyldisiloxane platinum complex, a divinyloctamethyltetrasiloxane platinum complex or a chloroplatinic acid alcohol solution; And / or, the inhibitor includes at least one of acetylene cyclohexanol, methyl butynol, tetramethyldivinyldisiloxane or trimethyl-dodecynol.

7. The organic silicone potting compound according to claim 1, characterized in that: The first silane coupling agent and the second silane coupling agent each independently include a methoxy mono-terminated silane coupling agent, an ethoxy mono-terminated silane coupling agent or a combination thereof; And / or, the chemical formula of the first silane coupling agent and the chemical formula of the second silane coupling agent are each independently represented by the following formula (I): In formula (I), R1 is a C1-C5 alkyl group; R2 is a C1-C5 alkyl group; x is 1-12; n is 10-60; and m is 1-3.

8. The organic silicone potting compound according to claim 1, characterized in that: The component A includes the following raw materials in parts by mass: 20 to 50 parts of a first vinyl silicone oil, 0.5 to 5 parts of a first silane coupling agent, 80 to 150 parts of a first powder, 1 to 10 parts of a first hollow glass microsphere, and 0.1 to 1 part of a catalyst; the component B includes the following raw materials in parts by mass: 10 to 30 parts of a second vinyl silicone oil, 5 to 25 parts of end-hydrogenated silicone oil, 0.5 to 5 parts of side-hydrogenated silicone oil, 0.5 to 5 parts of a second silane coupling agent, 80 to 150 parts of a second powder, 1 to 10 parts of a second hollow glass microsphere, and 0.01 to 0.5 parts of an inhibitor; the mass ratio of the component A to the component B is 1:(0.5 to 1.5).

9. A method for preparing the silicone potting compound according to any one of claims 1 to 8, characterized in that: The following steps are involved: The first vinyl silicone oil and the first silane coupling agent are mixed, and then the first powder and the first hollow glass microspheres are added and mixed, and finally the catalyst is added and mixed to obtain component A; the second vinyl silicone oil and the second silane coupling agent are mixed, and then the second powder and the second hollow glass microspheres are added and mixed, and finally the end hydrogen-containing silicone oil, the side hydrogen-containing silicone oil and the inhibitor are added and mixed to obtain component B.

10. Use of the organosilicon potting compound according to any one of claims 1 to 8 in the preparation of electronic components.

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