Highly flexible heat-conducting gasket and process for its production

Abstract

The present application relates to the technical field of heat-conducting gasket, especially to the field of IPC C08L83, further to a high-flexibility heat-conducting gasket and a preparation process thereof, which comprises the following raw materials by weight: 20-50 parts of vinyl silicone oil, 10-20 parts of hydrogen-containing silicone oil, 50-200 parts of heat-conducting filler, 0.1-2 parts of catalyst, 1-5 parts of coupling agent and 0.1-2 parts of inhibitor.The present application selects vinyl-terminated polydimethylsiloxane with different viscosities, controls the weight ratio, forms a moderate cross-linking degree between the hydrogen-containing silicone oil, and the heat-conducting filler has good dispersibility, so as to improve the flexibility of the heat-conducting gasket and the heat-conducting performance of the heat-conducting gasket.

Description

Technical Field

[0001] This invention relates to the field of thermal pad technology, particularly to the field of IPC C08L83, and further to a highly flexible thermal pad and its manufacturing process. Background Technology

[0002] As electronic components gradually develop towards higher integration and higher power, the heat flux density of these components increases dramatically, making efficient heat transfer and dissipation a problem that the electronics industry urgently needs to solve.

[0003] Thermal pads are a type of thermally conductive medium material synthesized through various processes using silicone as the base material and adding thermally conductive fillers. They are specifically designed to fill the air gap between heat-generating devices and heat sinks or metal bases. Their good flexibility allows them to be used to cover very uneven surfaces, thereby transferring heat away and protecting the components.

[0004] Chinese patent CN 107880842 A discloses a flexible thermally conductive pad and its preparation method. The flexible thermally conductive pad is composed of component A and component B in a certain proportion. The raw materials for preparing component A are a base adhesive and a catalyst, and the raw materials for preparing component B mainly include a base adhesive, a crosslinking agent, a chain extender, and a hydrogen-containing silane. This technical solution improves the flexibility of the thermally conductive pad to a certain extent, and the adhesion is also well controlled, ensuring good adhesion to the substrate and easy peeling from the release film, making it convenient to use. However, it requires a large amount of thermally conductive filler, and its thermal conductivity needs to be improved. Summary of the Invention

[0005] The first aspect of the present invention provides a highly flexible thermally conductive pad, comprising, by weight, the following raw materials: 20-50 parts vinyl silicone oil, 10-20 parts hydrogen-containing silicone oil, 50-200 parts thermally conductive filler, 0.1-2 parts catalyst, 1-5 parts coupling agent, and 0.1-2 parts inhibitor.

[0006] In some preferred embodiments, the vinyl silicone oil is selected from vinyl-terminated polydimethylsiloxane and / or vinyl-terminated polymethylvinylsiloxane.

[0007] Preferably, the vinyl silicone oil is a vinyl-terminated polydimethylsiloxane.

[0008] Preferably, the viscosity of the vinyl-terminated polydimethylsiloxane is 250-60000 mPa·s.

[0009] Preferably, the vinyl content of the vinyl-terminated polydimethylsiloxane is 0.08-0.7 wt%.

[0010] Preferably, the viscosity of the vinyl-terminated polydimethylsiloxane is 300-20000 mPa·s.

[0011] Preferably, the vinyl content of the vinyl-terminated polydimethylsiloxane is 0.55-0.7 wt%.

[0012] Preferably, the vinyl-terminated polydimethylsiloxane includes vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s.

[0013] Preferably, the weight ratio of the vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, the vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and the vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s is (5-10):(1-3):(3-6).

[0014] The applicant has discovered that by adding three vinyl-terminated polydimethylsiloxanes of different viscosities, the flexibility of thermal pads can be effectively improved. In particular, when the weight ratio of vinyl-terminated polydimethylsiloxanes with a viscosity of 500 mPa·s, 5000 mPa·s, and 10000 mPa·s is (5-10):(1-3):(3-6), the thermal conductivity of the thermal pads can be further improved while increasing their flexibility. The applicant hypothesizes that, on the one hand, the degree of cross-linking between vinyl-terminated polydimethylsiloxanes of different viscosities at this weight ratio and hydrogen-containing silicone oil is moderate, which will not lead to insufficient cross-linking or excessive cross-linking points, thereby improving the flexibility of the thermal pad; on the other hand, the thermally conductive filler can be uniformly dispersed in vinyl-terminated polydimethylsiloxanes of different viscosities at this weight ratio, reducing the agglomeration of the thermally conductive filler, thereby improving the thermal conductivity of the thermal pad.

[0015] In some preferred embodiments, the hydrogen-containing silicone oil is selected from side-chain hydrogen-containing silicone oils and / or end-chain hydrogen-containing silicone oils.

[0016] Preferably, the hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil and a terminal hydrogen-containing silicone oil.

[0017] Preferably, the weight ratio of the side-chain hydrogen-containing silicone oil to the end-chain hydrogen-containing silicone oil is (0.2-0.5):1.

[0018] Preferably, the side-chain hydrogen-containing silicone oil has a viscosity of 30-100 mPa·s and a hydrogen content of 0.5-1.5%.

[0019] Preferably, the viscosity of the hydrogen-containing silicone oil is 10-100 mPa·s, and the hydrogen content is 0.05-0.2%.

[0020] In some preferred embodiments, the thermally conductive filler is selected from one or more combinations of alumina, aluminum hydroxide, zinc oxide, boron nitride, aluminum nitride, ceramic powder, aluminum powder, graphite powder, silicon carbide powder, carbon fiber, carbon nanotubes, and graphene.

[0021] Preferably, the thermally conductive filler is a combination of zinc oxide, silicon carbide powder, and graphite powder.

[0022] Preferably, the weight ratio of zinc oxide, silicon carbide powder and graphite powder is (3-6):(1-3):(5-10).

[0023] Preferably, the zinc oxide has a particle size of 10-100 nm.

[0024] Preferably, the zinc oxide comprises zinc oxide with a particle size of 20 nm and zinc oxide with a particle size of 80 nm.

[0025] Preferably, the weight ratio of the 20nm zinc oxide to the 80nm zinc oxide is (0.5-2):1.

[0026] Preferably, the particle size of the silicon carbide powder is 50 nm.

[0027] Preferably, the graphite powder is flake graphite powder with a thickness of less than 40 nm and a flake diameter of 3-6 μm.

[0028] In some preferred embodiments, the catalyst is a platinum catalyst.

[0029] In some preferred embodiments, the coupling agent is selected from silane coupling agents or carbonate coupling agents.

[0030] In some preferred embodiments, the inhibitor is selected from any one of maleate ester, fumarate ester inhibitor, silanol inhibitor, and alkynol inhibitor.

[0031] Another aspect of the present invention provides a process for preparing a highly flexible thermally conductive pad, comprising the following steps:

[0032] By weight, the thermally conductive filler and coupling agent are first mixed evenly, then vinyl silicone oil, hydrogen-containing silicone oil, catalyst and inhibitor are added, and after being mixed evenly, they are calendered to obtain the final product.

[0033] Beneficial effects: This invention selects vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s, and controls their weight ratio to be (5-10):(1-3):(3-6), which can form a moderate degree of crosslinking with hydrogen-containing silicone oil. In addition, the zinc oxide, silicon carbide powder and graphite powder in the system have good dispersibility, thereby improving the flexibility of the thermal pad while also improving the thermal conductivity of the thermal pad. Detailed Implementation

[0034] Example 1

[0035] Example 1 provides a highly flexible thermally conductive pad, which, by weight, comprises the following raw materials: 40 parts vinyl silicone oil, 15 parts hydrogen-containing silicone oil, 100 parts thermally conductive filler, 1 part catalyst, 3 parts coupling agent, and 1 part inhibitor.

[0036] The vinyl silicone oil comprises vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s; the vinyl content of the vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, 5000 mPa·s, and 10000 mPa·s is 0.43 wt%, 0.18 wt%, and 0.12 wt%, respectively; purchased from Jiangsu Kexing New Materials Co., Ltd., with models V-500, V-5000, and V-10000, respectively.

[0037] The weight ratio of the vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, the vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and the vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s is 8:2:5.

[0038] The hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil and a terminal hydrogen-containing silicone oil.

[0039] The weight ratio of the side-chain hydrogen-containing silicone oil to the terminal hydrogen-containing silicone oil is 0.3:1.

[0040] The side-chain hydrogen-containing silicone oil has a viscosity of 30-100 mPa·s and a hydrogen content of 0.75±0.02%; it was purchased from Shanghai Silicon Power Advanced Materials Co., Ltd., model: MH750.

[0041] The viscosity of the hydrogen-containing silicone oil is 40-60 mPa·s, and the hydrogen content is 0.07±0.01%; it was purchased from Shanghai Silicon Power Advanced Materials Co., Ltd., model: MDH70.

[0042] The thermally conductive filler is a combination of zinc oxide, silicon carbide powder, and graphite powder.

[0043] The weight ratio of zinc oxide, silicon carbide powder, and graphite powder is 5:5:8.

[0044] The zinc oxide includes zinc oxide with a particle size of 20 nm and zinc oxide with a particle size of 80 nm; purchased from Bohuas Nanotechnology (Ningbo) Co., Ltd., with models Brofos-ZnO-20 and Brofos-ZnO-80 respectively.

[0045] The weight ratio of zinc oxide with a particle size of 20 nm to zinc oxide with a particle size of 80 nm is 1:1.

[0046] The silicon carbide powder has a particle size of 50 nm and was purchased from Shanghai Chaowei Nanotechnology Co., Ltd., model number: CW-TiC-001.

[0047] The graphite powder is flake-shaped graphite powder with a thickness of less than 40 nm and a flake diameter of 3-6 μm, and was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0048] The catalyst is a platinum catalyst, purchased from Guangzhou Silicon Friends New Materials Technology Co., Ltd., model: PT-5000 series.

[0049] The coupling agent is a silane coupling agent, purchased from Anhui Sibao Organosilicon New Materials Co., Ltd., model: GX-171.

[0050] The inhibitor is an alkynol inhibitor, purchased from Shanghai Silicon Power Advanced Materials Co., Ltd., model: MA8900.

[0051] A process for manufacturing a highly flexible thermally conductive pad includes the following steps:

[0052] By weight, zinc oxide, silicon carbide powder, graphite powder and silane coupling agent are first mixed evenly. Then, vinyl-terminated polydimethylsiloxane of different viscosities, side-chain hydrogen-containing silicone oil, end-hydrogen-containing silicone oil, platinum catalyst and alkynol inhibitor are added. After being mixed evenly, the mixture is calendered to obtain the final product.

[0053] Example 2

[0054] Example 2 provides a highly flexible thermally conductive pad, the specific implementation of which is the same as that of Example 1, except that the vinyl silicone oil includes vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s and vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, in a weight ratio of 8:2.

[0055] Example 3

[0056] Example 3 provides a highly flexible thermally conductive pad, the specific implementation of which is the same as that of Example 1, except that the vinyl silicone oil includes vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s and vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s, in a weight ratio of 2:5.

[0057] Example 4

[0058] Example 4 provides a highly flexible thermally conductive pad, the specific implementation of which is the same as that of Example 1, except that the zinc oxide has a particle size of 150 nm and is purchased from Bohuas Nanotechnology (Ningbo) Co., Ltd., model number Brofos-ZnO-100.

[0059] Example 5

[0060] Example 5 provides a highly flexible thermally conductive pad, the specific implementation of which is the same as that of Example 1, except that the thermally conductive filler is a combination of zinc oxide and silicon carbide powder in a weight ratio of 1:1.

[0061] Example 6

[0062] Example 6 provides a highly flexible thermally conductive pad, the specific implementation of which is the same as that of Example 1, except that the weight ratio of the vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, the vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and the vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s is 15:2:2.

[0063] Performance testing: The highly flexible thermally conductive pads prepared in Examples 1-6 were subjected to the following tests:

[0064] 1. Thermal conductivity: The results are recorded in Table 1, referring to ASTM D5470 standard.

[0065] 2. Tensile strength and elongation at break: The results are recorded in Table 1, referring to GB / T 528-2009 standard.

[0066] 3. Hardness: The Shore hardness tester was used to test the hardness according to the AM type, and the results are recorded in Table 1.

[0067] Test Results

[0068] Table 1:

[0069]

Claims

1. A highly flexible thermally conductive pad, characterized in that, By weight, it includes the following raw materials: 20-50 parts vinyl silicone oil, 10-20 parts hydrogen-containing silicone oil, 50-200 parts thermally conductive filler, 0.1-2 parts catalyst, 1-5 parts coupling agent, and 0.1-2 parts inhibitor. The vinyl silicone oil is a vinyl-terminated polydimethylsiloxane, wherein the vinyl content of the vinyl-terminated polydimethylsiloxane is 0.08-0.7 wt%, and the vinyl-terminated polydimethylsiloxane includes vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s, wherein the weight ratio of the vinyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, the vinyl-terminated polydimethylsiloxane with a viscosity of 5000 mPa·s, and the vinyl-terminated polydimethylsiloxane with a viscosity of 10000 mPa·s is (5-10):(1-3):(3-6). The hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil and a terminal hydrogen-containing silicone oil; the weight ratio of the side-chain hydrogen-containing silicone oil to the terminal hydrogen-containing silicone oil is (0.2-0.5):1; the viscosity of the side-chain hydrogen-containing silicone oil is 30-100 mPa·s, and the hydrogen content is 0.5-1.5%; the viscosity of the terminal hydrogen-containing silicone oil is 10-100 mPa·s, and the hydrogen content is 0.05-0.2%. The thermally conductive filler is a combination of zinc oxide, silicon carbide powder, and graphite powder; the weight ratio of zinc oxide, silicon carbide powder, and graphite powder is (3-6):(1-3):(5-10); the zinc oxide includes zinc oxide with a particle size of 20 nm and zinc oxide with a particle size of 80 nm; the weight ratio of the 20 nm zinc oxide to the 80 nm zinc oxide is (0.5-2):1; the silicon carbide powder has a particle size of 50 nm; the graphite powder is flake graphite powder with a thickness of less than 40 nm and a flake diameter of 3-6 µm.

2. A manufacturing process for the high-flexibility thermally conductive pad according to claim 1, characterized in that, Includes the following steps: By weight, the thermally conductive filler and coupling agent are first mixed evenly, then vinyl silicone oil, hydrogen-containing silicone oil, catalyst and inhibitor are added, and after being mixed evenly, they are calendered to obtain the final product.

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