Low-hardness high-resilience heat-conducting organic silicon gel and preparation method thereof

Abstract

The invention belongs to the technical field of heat-conducting interface materials, and particularly relates to low-hardness high-resilience heat-conducting organic silicon gel and a preparation method thereof. The organosilicone gel is prepared from the following components: vinyl-terminated polydimethylsiloxane, hydrogen-containing polysiloxane, an iso-bifunctional chain extender, a heat-conducting powder surface treating agent, heat-conducting filler, a curing inhibitor and a platinum catalyst. The organic silica gel prepared by the preparation method disclosed by the invention has the excellent properties of high heat conductivity, low hardness, difficulty in cracking, capability of keeping high resilience and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of heat-conducting interface materials, and particularly relates to a low-hardness high-resilience heat-conducting silicone gel and a preparation method thereof. BACKGROUND

[0002] In order to solve the heat dissipation problem of electronic components, silicone heat-conducting interface materials are widely used to fill the micro gaps between components and heat sinks, and to reduce the heat transfer resistance. In the face of the heat dissipation demand of high-performance, miniaturized and highly integrated electronic components with power greater than 100W in the fields of 5G, AI, etc., the demand for the thermal conductivity coefficient of the thermal interface material is getting higher and higher, and therefore the loading amount of the heat-conducting filler in the thermal interface material is also higher, usually greater than 90wt% or even greater than 95wt%. In the case of high heat-conducting filler loading, the mechanical properties of the silicone thermal interface material deteriorate rapidly, such as hardening and cracking.

[0003] Patent application with publication number CN119350852A discloses a high-elongation-at-break heat-conducting gel and a preparation method thereof, wherein the heat-conducting gel solves the reliability problem of the heat-conducting gel under long-term vibration and dynamic operation; the introduction of special silicone oil improves the powder surface coverage and enhances the displacement ability between silicone macromolecular segments; and the heat-conducting gel has high elongation at break and good deformation ability. The heat-conducting gel can be applied to the heat dissipation scene in the field of new energy vehicles, but does not meet the heat dissipation demand of electronic components with medium and high power and above.

[0004] In order to reduce the viscosity of the material, a large amount of powder treatment agent is usually added to improve the compatibility between the heat-conducting filler and the silicone matrix, and in addition, in order to obtain a soft thermal interface material that closely adheres to the heat dissipation interface, the crosslinking degree of the polymer network needs to be controlled very low, usually less than 15%. The soft heat-conducting gel prepared by low crosslinking density and a large amount of non-reactive powder treatment agent is very easy to deform irreversibly under external force, loses resilience, and inevitably appears virtual connection, defects, etc., affecting the heat dissipation performance.

[0005] In summary, the existing technology has obvious defects, and therefore it is of great significance to develop a silicone gel with high heat conduction, low hardness, not easy to crack, and high resilience. SUMMARY

[0006] The present application provides a low-hardness high-resilience heat-conducting silicone gel and a preparation method thereof, which has high heat conduction, low hardness, is not easy to crack, and can maintain high resilience and other excellent properties.

[0007] The technical scheme for solving the above technical problems is as follows: a low-hardness high-resilience heat-conducting silicone gel, which is composed of the following components: vinyl-terminated polydimethylsiloxane, hydrogen-containing polysiloxane, isobifunctional chain extender, heat-conducting powder surface treatment agent, heat-conducting filler, curing inhibitor and platinum catalyst.

[0008] Further, the content of the vinyl-terminated polydimethylsiloxane is 2-10 wt%, the content of the hydrogen-containing polysiloxane is 0.2-1 wt%, the content of the isobifunctional chain extender is 1-5 wt%, the content of the heat-conducting powder surface treatment agent is 0.5-2.5 wt%, the content of the curing inhibitor is 50-800 ppm, the content of the platinum catalyst is 1-5 ppm, and the heat-conducting filler is the rest; preferably, the content of the curing inhibitor is 100-500 ppm.

[0009] Further, the vinyl-terminated polydimethylsiloxane is at least one of the viscosity range of 50-1000 mpa.s at 25 DEG C.

[0010] Further, the vinyl-terminated polydimethylsiloxane is at least one of the viscosity range of 50-1000 mpa.s at 25 DEG C.

[0011] Further, the hydrogen-containing polysiloxane includes end hydrogen silicone oil and side hydrogen-containing silicone oil, wherein the end hydrogen silicone oil has silicon hydrogen bonds at both ends of the molecule, and the side hydrogen-containing silicone oil has silicon hydrogen bonds in the side chain of the molecule.

[0012] Further, the end hydrogen silicone oil has a viscosity range of 5-50 mpa.s at 25 DEG C, and the hydrogen content in the end hydrogen silicone oil is 0.02-0.2 wt%; the side hydrogen-containing silicone oil has a viscosity range of 50-1500 mpa.s at 25 DEG C, and the hydrogen content in the side hydrogen-containing silicone oil is 0.05-0.12 wt%.

[0013] Further, the ratio of the hydrogen content in the end hydrogen silicone oil and the side hydrogen-containing silicone oil is (2-10):1.

[0014] Further, the isobifunctional chain extender is alpha-hydro-omega-vinyl isobifunctional chain-terminated polydimethylsiloxane, and its structural formula is as follows:

[0015]

[0016] Further, the heat-conducting powder surface treatment agent is at least one of the reactive heat-conducting powder surface treatment agent and the non-reactive heat-conducting powder surface treatment agent, and preferably is a mixture of the reactive heat-conducting powder surface treatment agent and the non-reactive heat-conducting powder surface treatment agent.

[0017] Furthermore, the reactive thermally conductive powder surface treatment agent is α-vinyl-Ω-trimethoxy-terminated polydimethylsiloxane, and its chemical structure is:

[0018]

[0019] Wherein, n is 5-30.

[0020] Furthermore, the non-reactive thermally conductive powder surface treatment agent is α-methyl-Ω-trimethoxy-terminated polydimethylsiloxane.

[0021] Furthermore, the mass ratio of the reactive thermally conductive powder surface treatment agent, the non-reactive thermally conductive powder surface treatment agent and the heterobifunctional chain extender is 1:(2-3):(1-5.5).

[0022] Furthermore, the thermally conductive filler includes aluminum nitride, silicon carbide, diamond, zinc oxide, aluminum oxide and silver powder.

[0023] Furthermore, the thermally conductive filler includes a thermally conductive filler with a large particle size, a thermally conductive filler with a medium particle size, and a thermally conductive filler with a small particle size.

[0024] Furthermore, the large-particle thermal conductive filler has an average particle size D 50大 At least one of aluminum nitride, silicon carbide and diamond with a particle size of 30-50 μm; the medium-sized thermal conductive filler has an average particle size of D 50中 The small-particle thermal conductive filler has an average particle size of D 50小 The invention relates to at least one of zinc oxide, aluminum oxide and spherical silver powder with a particle size of 0.3-1 μm.

[0025] Furthermore, among the large-particle thermal conductive fillers, the maximum particle size D max and average particle size D 50大 The relationship is: D 50大 ≤D max ≤2D 50大 .

[0026] Furthermore, the mass ratio of the thermally conductive powder surface treatment agent to the thermally conductive filler is 1:(50-200).

[0027] Furthermore, the curing inhibitor is an alkynol inhibitor, preferably at least one of ethynylcyclohexanol and tris[(1,1-dimethyl-2-propynyl)oxy]methylsilane.

[0028] Furthermore, the platinum catalyst is a Custer platinum catalyst, preferably a platinum-divinyltetramethyldisiloxane complex diluted with vinyl silicone oil (Custer platinum catalyst).

[0029] Further, the preparation method of the reactive heat-conductive powder surface treatment agent comprises the following steps:

[0030] S1, under the condition of inert gas, 40 DEG C below zero to 78 DEG C below zero, n-butyllithium is slowly added to tetravinyl tin to react, and a vinyl lithium initiator reaction solution is obtained;

[0031] S2, after refluxing and dehydrating hexamethylcyclotrisiloxane under inert gas, a polar promoter is added, and after stirring, a mixed solution is obtained;

[0032] S3, under inert gas, the vinyl lithium initiator reaction solution in step S1 is introduced into the mixed solution in step S2, and trimethoxysilane is added to react;

[0033] S4, impurity salt is removed by adding an adsorbent, and a heat-conductive powder surface treatment agent, i.e., alpha-vinyl-omega-trimethoxyl-terminated polydimethylsiloxane, is obtained.

[0034] Further, in step S1, the molar ratio of the n-butyllithium to the tetravinyl tin is 1:4.

[0035] Further, in step S1, the reaction solvent is preferably ethyl ether or tetrahydrofuran, the reaction time is 0.5-5h, and after reaction, the temperature is returned to-15-0 DEG C.

[0036] Further, in step S2, the polar promoter is at least one of tetrahydrofuran, N, N-dimethylformamide and dimethyl sulfoxide.

[0037] Further, in step S2, the reaction solvent is preferably anhydrous toluene, the reflux temperature is 130-140 DEG C, the reflux dehydration time is 1-5h, and after reflux dehydration, the temperature is returned to-15-0 DEG C.

[0038] Further, in step S2, after adding the polar promoter, stirring is carried out for-60 min.

[0039] Further, in step S3, the molar ratio of the vinyl lithium initiator, hexamethylcyclotrisiloxane and trimethoxysilane is 1:(2-10):(1.01-1.1).

[0040] Further, in step S4, the adsorbent is at least one of neutral aluminum oxide, activated carbon and diatomite.

[0041] The application also discloses a preparation method of low-hardness high-rebound heat-conductive silicone gel.

[0042] (1) heat-conductive fillers are added into a high-speed dispersion kettle for high-speed pre-shearing;

[0043] (2) adding part of the thermal conductive powder surface treatment agent in the form of spraying to dry pre-modify the thermal conductive filler;

[0044] (3) adding vinyl-terminated polydimethylsiloxane, isobifunctional chain extender, and another part of the thermal conductive powder surface treatment agent, and stirring uniformly;

[0045] (4) sequentially adding the hydrogen-containing polysiloxane, the curing inhibitor and the platinum-gold catalyst, and mixing uniformly;

[0046] (5) vacuum degassing, and storing at -40-0℃ after filling.

[0047] Further, step (4) controls the temperature at 20-30℃.

[0048] The present application has the following beneficial effects:

[0049] (1) The thermal conductive silicone gel prepared by the preparation method has the following advantages: the non-reactive thermal conductive powder surface treatment agent and the reactive thermal conductive powder surface treatment agent are introduced to balance the hardness and elasticity of the material, improve the plasticizing effect, and the isobifunctional chain extender alpha-hydrogen-omega-vinyl isobifunctional vinyl-terminated polydimethylsiloxane is introduced to increase the polymer matrix chain entanglement and increase the material toughness, so that the thermal conductive gel has further improved thermal conductivity, and the problem of low hardness and high resilience of the gel is solved. The thermal conductive silicone gel has low hardness, high resilience and high thermal conductivity, and the thermal interface contact is more closely, so that better heat dissipation effect can be achieved.

[0050] (2) The reactive thermal conductive powder surface treatment agent alpha-vinyl-omega-trimethoxyl-terminated polydimethylsiloxane has the advantages of simple operation and high yield. DETAILED DESCRIPTION

[0051] The specific embodiments of the present application will be described in detail below. The present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited by the specific embodiments disclosed.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used are only for describing specific embodiments, not for limiting the present application.

[0053] A low-hardness high-resilience thermal conductive silicone gel, the silicone gel is composed of the following components: vinyl-terminated polydimethylsiloxane, hydrogen-containing polysiloxane, isobifunctional chain extender, thermal conductive powder surface treatment agent, thermal conductive filler, curing inhibitor, platinum-gold catalyst.

[0054] Specifically, the content of the vinyl-terminated polydimethylsiloxane is 2-10 wt%, the content of the hydrogen-containing polysiloxane is 0.2-1 wt%, the content of the isobifunctional chain extender is 1-5 wt%, the content of the thermal conductive powder surface treatment agent is 0.5-2.5 wt%, the addition amount of the curing inhibitor is 50-800 ppm, the addition amount of the platinum catalyst is 1-5 ppm, and the thermal conductive filler is the remainder; wherein the preferred addition amount of the curing inhibitor is 100-500 ppm.

[0055] Specifically, the vinyl-terminated polydimethylsiloxane is at least one of 25℃ viscosity range 50-1000 mpa.s.

[0056] More specifically, the vinyl-terminated polydimethylsiloxane is at least one of 25℃ viscosity range 50-500 mpa.s and vinyl content 0.4-1.8 wt%.

[0057] Specifically, the hydrogen-containing polysiloxane includes end hydrogen silicone oil and side hydrogen-containing silicone oil, wherein the end hydrogen silicone oil has silicon hydrogen bonds at both ends of the molecule, and the side hydrogen-containing silicone oil has silicon hydrogen bonds in the side chain of the molecule.

[0058] More specifically, the end hydrogen silicone oil has a 25℃ viscosity range of 5-50 mpa.s, and the hydrogen content in the end hydrogen silicone oil is 0.02-0.2 wt%; the side hydrogen-containing silicone oil has a 25℃ viscosity range of 50-1500 mpa.s, and the hydrogen content in the side hydrogen-containing silicone oil is 0.05-0.12 wt%.

[0059] Further, the ratio of the hydrogen content in the end hydrogen silicone oil and the side hydrogen-containing silicone oil is (2-10):1.

[0060] Specifically, the isobifunctional chain extender is α-hydro-Ω-vinyl isobifunctional terminated polydimethylsiloxane, and its structural formula is as follows:

[0061]

[0062] Specifically, the thermal conductive powder surface treatment agent is at least one of a reactive thermal conductive powder surface treatment agent and a non-reactive thermal conductive powder surface treatment agent, and is preferably a mixture of a reactive thermal conductive powder surface treatment agent and a non-reactive thermal conductive powder surface treatment agent.

[0063] Specifically, the reactive thermal conductive powder surface treatment agent is α-vinyl-Ω-trimethoxyl terminated polydimethylsiloxane, and its chemical structural formula is as follows:

[0064]

[0065] Wherein, n is 5-30.

[0066] Specifically, the non-reactive thermally conductive powder surface treatment agent is α-methyl-Ω-trimethoxy-terminated polydimethylsiloxane.

[0067] More specifically, the mass ratio of the reactive thermally conductive powder surface treatment agent, the non-reactive thermally conductive powder surface treatment agent, and the heterobifunctional chain extender is 1:(2-3):(1-5.5).

[0068] Specifically, the thermally conductive filler includes aluminum nitride, silicon carbide, diamond, zinc oxide, aluminum oxide and silver powder.

[0069] Specifically, the thermally conductive filler includes a thermally conductive filler with a large particle size, a thermally conductive filler with a medium particle size, and a thermally conductive filler with a small particle size.

[0070] Specifically, the large-particle thermal conductive filler has an average particle size D 50大 At least one of aluminum nitride, silicon carbide and diamond with a particle size of 30-50 μm; the medium-sized thermal conductive filler has an average particle size of D 50中 The small-particle thermal conductive filler has an average particle size of D 50小 The invention relates to at least one of zinc oxide, aluminum oxide and spherical silver powder with a particle size of 0.3-1 μm.

[0071] Specifically, among the large-particle thermal conductive fillers, the maximum particle size D max and average particle size D 50大 The relationship is: D 50大 ≤D max ≤2D 50大 .

[0072] More specifically, the mass ratio of the thermally conductive powder surface treatment agent to the thermally conductive filler is 1:(50-200).

[0073] Specifically, the curing inhibitor is an acetylenic alcohol inhibitor, preferably at least one of ethynylcyclohexanol and tris[(1,1-dimethyl-2-propynyl)oxy]methylsilane.

[0074] Specifically, the platinum catalyst is a Custer platinum catalyst, preferably a platinum-divinyltetramethyldisiloxane complex diluted with vinyl silicone oil (Custer platinum catalyst).

[0075] Specifically, the preparation method of the reactive thermally conductive powder surface treatment agent comprises the following steps:

[0076] S1. Slowly add n-butyl lithium to tetravinyl tin solution under inert gas at -78°C to react and obtain vinyl lithium initiator reaction solution;

[0077] S2, after removing water under reflux of hexamethylcyclotrisiloxane under inert gas, a polar promoter is added, and after stirring, a mixed solution is obtained;

[0078] S3, the vinyl lithium initiator reaction solution in step S1 is introduced into the mixed solution in step S2 under inert gas, and trimethoxysilane is added for reaction;

[0079] S4, an adsorbent is added to remove impurity salt, and a heat-conducting powder surface treatment agent, i.e., α-vinyl-Ω-trimethoxyl-terminated polydimethylsiloxane, is obtained.

[0080] The synthesis mechanism of the reactive heat-conducting powder surface treatment agent is as follows:

[0081]

[0082] Specifically, in step S1, the molar ratio of the n-butyllithium to the tetra-vinyl tin is 1:4, and the reaction solvent is preferably ethyl ether or tetrahydrofuran.

[0083] Specifically, the n-butyllithium in the embodiment of the present application is a 1.6 mol / L n-hexane solution, and the tetra-vinyl tin is an ethyl ether solution with a concentration of 1.6-2.7 mol / L.

[0084] More specifically, in step S1, the specific operation for preparing the vinyl lithium initiator is as follows:

[0085] Under the condition of nitrogen, the tetra-vinyl tin is dissolved in ethyl ether, cooled to -78°C, and the n-butyllithium solution is slowly added dropwise into the tetra-vinyl tin solution under stirring, and after reaction for 0.5-5 h, the temperature is returned to -15-0°C to obtain the vinyl lithium initiator reaction solution.

[0086] Specifically, in step S2, the polar promoter is at least one of tetrahydrofuran, N, N-dimethylformamide, and dimethyl sulfoxide, and the polar promoter used in the embodiment of the present application is tetrahydrofuran.

[0087] More specifically, the specific operation of step S2 is as follows:

[0088] Under inert gas, the hexamethylcyclotrisiloxane is dissolved in anhydrous toluene, and water is removed under reflux for 1-5 h at 130-140°C, the temperature is lowered to -15-0°C, the polar promoter is added, and stirring is performed for 5-60 min to obtain a mixed solution.

[0089] Specifically, in step S3, the molar ratio of the vinyl lithium initiator, the hexamethylcyclotrisiloxane, and the trimethoxysilane is 1:(2-10):(1.01-1.1).

[0090] More specifically, the specific operation of step S3 is as follows:

[0091] The vinyl lithium initiator reaction solution in step S1 is introduced into the mixed solution in step S2 through double-needle under inert gas, ice water bath reaction, and when the conversion rate of hexamethylcyclotrisiloxane is greater than 90%, trimethoxysilane is added for reaction for 1-6h.

[0092] In step S4, the adsorbent is at least one of neutral aluminum oxide, activated carbon and diatomite.

[0093] More specifically, the specific operation of step S4 is:

[0094] The impurity salt is removed by adding the adsorbent and stirring for 1-12h, the adsorbent is removed by filtration, the filtrate is collected, the solvent and other low-boiling impurities are removed by vacuum distillation, and the heat-conducting powder surface treatment agent, i.e., alpha-vinyl-omega-trimethoxyl-terminated polydimethylsiloxane, is obtained.

[0095] The application also discloses a preparation method of low-hardness high-rebound heat-conducting silicone gel.

[0096] (1) The heat-conducting filler is added into a high-speed dispersion kettle for high-speed pre-shearing;

[0097] (2) A part of the heat-conducting powder surface treatment agent is added in a spraying manner to pre-modify the heat-conducting filler in a dry method;

[0098] (3) Vinyl-terminated polydimethylsiloxane, isobifunctional chain extender and another part of the heat-conducting powder surface treatment agent are added and stirred uniformly;

[0099] (4) The temperature is controlled at 20-30℃, the hydrogen-containing polysiloxane is added and stirred uniformly, the curing inhibitor is added and stirred uniformly, and finally the platinum gold catalyst is added and mixed uniformly;

[0100] (5) Vacuum degassing is performed, and the product is stored at-40-0℃ after filling.

[0101] The components used in the examples and comparative examples of the application are only used to better explain the application technology, and are not limited to the application technology. The components used in the application are all from commercial products, except that D1 is synthesized in the examples of the application. The components used in the examples and comparative examples are as follows:

[0102] A1: Vinyl-terminated polydimethylsiloxane (25℃ viscosity 50mPa.s, vinyl content 1.68wt%, Chuanhe Chemical).

[0103] A2: Mono-vinyl-terminated polydimethylsiloxane (25℃ viscosity 350mPa.s, vinyl content 0.4wt%, Chuanhe Chemical).

[0104] A3: Vinyl-terminated polydimethylsiloxane (viscosity at 25°C 500 mPa.s, vinyl content 0.43 wt%, Kawaken Chemicals).

[0105] B1: Hydrogen-terminated polydimethylsiloxane (viscosity 15 mPa.s, H content 0.13 wt%, Hayashibara Silicone, HHD-14).

[0106] B2: Hydrogen-terminated polydimethylsiloxane (viscosity 500 mPa.s, H content 0.11 wt%, Wacker Chemical, Crosslinker 120).

[0107] C: Alpha-hydro-omega-vinyl isobifunctional terminated polydimethylsiloxane (Vi-PDMS-H, GELEST, DMS-HV22, 25°C 150-250 mPa-s).

[0108] D1: Alpha-vinyl-omega-trimethoxyl terminated polydimethylsiloxane (product synthesized in Example 1 of the present invention, degree of polymerization 25).

[0109] D2: Alpha-methyl-omega-trimethoxyl terminated polydimethylsiloxane (degree of polymerization 25).

[0110] E1: Monocrystal alumina with average particle size D 50小 0.5 μm (Sumitomo Chemical, AA04).

[0111] E2: Rod-shaped zinc oxide with average particle size D 50小 0.6 μm (Jiangsu Zhenzhong Zinc Industry).

[0112] E3: Spherical silver powder with average particle size D 50小 0.8 μm (Yuan Yang Aluminum Industry).

[0113] E4: Spherical aluminum nitride with average particle size D 50中 2 μm (Yuan Yang Aluminum Industry).

[0114] E5: Spherical aluminum nitride with average particle size D 50中 D50 5 μm (Yuan Yang Aluminum Industry).

[0115] E6: Spherical aluminum nitride with average particle size D 50大 25 μm, Dmax 50 μm (Yuan Yang Aluminum Industry).

[0116] E7: Spherical diamond with average particle size D 50大 30 μm, Dmax 50 μm (Yuan Yang Aluminum Industry).

[0117] E8: Spherical aluminum nitride with average particle size D 50大 50 μm, Dmax 100 μm (Yuan Yang Aluminum Industry).

[0118] E9: average particle size D 50大 Silicon carbide micropowder (Yuan Yang Aluminum Industry) with a particle size of 50 μm and a Dmax of 100 μm.

[0119] E10: average particle size D 50大 Spherical diamond (Yuan Yang Aluminum Industry) with a particle size of 50 μm and a Dmax of 100 μm.

[0120] F1 : 1-ethynylcyclohexanol (Cas No. 78-27-3, Aldrich Reagent)

[0121] F2: Tris[(1,1 -dimethyl-2-propynyl)oxy]methylsilane (Cas No. 83817-71 -4, Aldrich Reagent)

[0122] G: Karstedt's platinum catalyst (Heraeus, Karstedt Catalyst, Pt = 5000 ppm, Jiyan Platinum Industry)

[0123] Example 1

[0124] Preparation of an alpha-vinyl-omega-trimethoxyl terminated polydimethylsiloxane, the specific preparation steps are as follows:

[0125] S1, Preparation of vinyl lithium initiator: 2.27 g (10 mmol) of tetra-vinyl tin was dissolved in 10 mL of diethyl ether under nitrogen, cooled to -78°C, and 25 mL of n-butyllithium solution was slowly added dropwise into the tetra-vinyl tin diethyl ether solution under stirring, after 2 h of reaction, the temperature was returned to 0°C, and the vinyl lithium initiator reaction solution was obtained.

[0126] S2, 72 g (320 mmol) of hexamethylcyclotrisiloxane was dissolved in 100 mL of anhydrous toluene under inert gas, and water was removed by refluxing at 130-140°C for 2 h, the temperature was lowered to 0°C, 20 mL of tetrahydrofuran was added, and the mixture was stirred for 10 min.

[0127] S3, the vinyl lithium initiator reaction solution in step S1 was introduced into the mixture solution in step S2 through a double needle under inert gas, and the reaction was carried out in an ice water bath, when the conversion rate of hexamethylcyclotrisiloxane was greater than 90%, 6.9 g (44 mmol) of trimethoxysilane was added, and the reaction was continued for 1 h.

[0128] S4, 2 g of activated carbon and 1 g of diatomite were added and stirred for 2 h to adsorb the generated impurity salt, the adsorbent was removed by filtration, the filtrate was collected, and the solvent and other low boiling point impurities were removed by vacuum distillation, 66 g of heat conductive powder surface treatment agent was obtained, which was alpha-vinyl-omega-trimethoxyl terminated polydimethylsiloxane, the viscosity at 25°C was 25 mpa.s, and the yield was 81.5%.

[0129] The components used for preparing a low hardness high resilience heat conductive silicone gel of Example 1 are as follows:

[0130] Vinyl terminated polydimethylsiloxane is A2 (mono vinyl terminated polydimethylsiloxane, 25°C viscosity 350 mPa.s, vinyl content 0.4 wt%) and A3 (vinyl terminated polydimethylsiloxane, 25°C viscosity 500 mPa.s, vinyl content 0.43 wt%).

[0131] Hydrogen containing polydimethylsiloxane is B1 (end hydrogen containing polydimethylsiloxane, viscosity 15 mPa.s, H content 0.13 wt%) and B2 (side hydrogen containing polydimethylsiloxane, viscosity 500 mPa.s, H content 0.11 wt%).

[0132] Isobifunctional chain extender is C (a-hydro-Ω vinyl isobifunctional terminated polydimethylsiloxane).

[0133] Heat conductive powder surface treatment agent is D1 (a-vinyl-Ω-trimethoxy terminated polydimethylsiloxane) and D2 (a-methyl-Ω-trimethoxy terminated polydimethylsiloxane) synthesized in Example 1.

[0134] Heat conductive filler is E1 (monocrystal alumina, average particle size D 50小 0.5 μm), E2 (rod-like zinc oxide, average particle size D 50小 0.6 μm), E4 (spherical aluminum nitride, average particle size D 50中 2 μm), and E6 (spherical aluminum nitride, average particle size D 50大 25 μm, Dmax 50 μm).

[0135] Curing inhibitor is F1 : 1-ethynylcyclohexanol.

[0136] Platinum gold catalyst is G: Karstedt platinum gold catalyst (Heraeus, Karstedt Catalyst, Pt = 5000 ppm).

[0137] Preparation of a low hardness high resilience heat conductive silicone gel, the specific preparation steps are as follows:

[0138] (1) The heat conductive filler 20 g E1, 30 g E2, 70 g E4 and 120 g E6 are added to a high speed dispersion kettle for high speed pre-shearing;

[0139] (2) The heat conductive powder surface treatment agent 0.6 g D1 is added by spraying to dry pre-modify the heat conductive filler for 2 h;

[0140] (3) Add vinyl-terminated polydimethylsiloxane 5.0 g A2, 5.0 g A3, isobifunctional chain extender 2.0 g C, and thermal conductive powder surface treatment agent 1.2 g D2, high-speed dispersion 2 h, control temperature less than 60°C;

[0141] (4) Control temperature at 20-30°C, add hydrogen-containing polysiloxane 0.6 g B1 and 0.2 g B2 dispersion 0.5 h, then add curing inhibitor 0.06 g F1 and disperse uniformly, finally add platinum catalyst 0.1 g G and mix uniformly;

[0142] (5) Vacuum degassing 10 min, fill and store at -40-0°C.

[0143] Example 2

[0144] Preparation of an α-vinyl-Ω-trimethoxyl-terminated polydimethylsiloxane, the specific preparation steps are the same as in Example 1.

[0145] The components used in this example 2 to prepare a low hardness high resilience thermal conductive silicone gel are the same as in Example 1, the difference is:

[0146] Vinyl-terminated polydimethylsiloxane is A1 (vinyl-terminated polydimethylsiloxane, 25°C viscosity 50 mPa.s, vinyl content 1.68 wt%) and A3 (vinyl-terminated polydimethylsiloxane, 25°C viscosity 500 mPa.s, vinyl content 0.43 wt%).

[0147] Thermal conductive filler is E1 (single crystal alumina with average particle size D 50小 0.5 μm), E2 (rod-shaped zinc oxide with average particle size D 50小 0.6 μm), E4 (spherical aluminum nitride with average particle size D 50中 2 μm), E6 (spherical aluminum nitride with average particle size D 50大 25 μm, Dmax 50 μm), and E7 (spherical diamond with average particle size D 50大 30 μm, Dmax 50 μm).

[0148] Curing inhibitor is F2: tris[(1,1-dimethyl-2-propynyl)oxy]methylsilane.

[0149] Preparation of a low hardness high resilience thermal conductive silicone gel, the specific preparation steps are as follows:

[0150] (1) Add thermal conductive filler 20 g E1, 30 g E2, 70 g E4, 90 g E6 and 50 g E7 into a high-speed dispersion kettle for high-speed pre-shearing;

[0151] (2) adding 0.6 g of thermal conductive powder surface treatment agent D1 by spraying, and pre-modifying the thermal conductive filler by dry method for 2 h;

[0152] (3) Add 5.0 g of vinyl-terminated polydimethylsiloxane A1, 5.0 g of A3, 2.0 g of heterobifunctional chain extender C, and 1.2 g of thermal conductive powder surface treatment agent D2, and disperse at high speed for 2 h, controlling the temperature to be less than 60°C;

[0153] (4) Control the temperature at 20-30°C, add 1.4g of hydrogenated polysiloxane B1 and 0.5g of B2 and disperse for 0.5h, then add 0.1g of curing inhibitor F2 and disperse evenly, and finally add 0.1g of platinum catalyst G and mix evenly;

[0154] (5) Vacuum degassing for 10 minutes and store at -40-0℃ after filling.

[0155] Example 3

[0156] The preparation of an α-vinyl-Ω-trimethoxy-terminated polydimethylsiloxane is carried out in the same manner as in Example 1.

[0157] The components used in Example 3 to prepare a low-hardness, high-resilience, thermally conductive silicone gel are the same as those in Example 1, except that:

[0158] The vinyl terminated polydimethylsiloxanes are A1 (vinyl terminated polydimethylsiloxane, viscosity 50 mPa.s at 25° C., vinyl content 1.68 wt %) and A2 (monovinyl terminated polydimethylsiloxane, viscosity 350 mPa.s at 25° C., vinyl content 0.4 wt %).

[0159] Thermal conductive filler is E1 (average particle size D 50小 0.5 μm single crystal aluminum oxide), E2 (average particle size D 50小 0.6μm rod-shaped zinc oxide), E3 (average particle size D 50小 0.8μm spherical silver powder), E5 (average particle size D 50中 D50 is 5μm spherical aluminum nitride), E8 (average particle size D 50大 50μm, Dmax 100μm spherical aluminum nitride) and E9 (average particle size D 50大 of 50 μm and silicon carbide powder with Dmax of 100 μm).

[0160] Preparation of a low-hardness, high-rebound, thermally conductive silicone gel, the specific preparation steps are as follows:

[0161] (1) Put the heat conductive filler 15g El, 30g E2, 10g E3, 80g E5, 110g E8 and 50g E9 into a high-speed dispersion kettle for high-speed pre-shearing;

[0162] (2) Add the heat conductive powder surface treatment agent 0.8g Dl by spraying to dry pre-modify the heat conductive filler for 2h;

[0163] (3) Add the vinyl-terminated polydimethylsiloxane 5.0g Al, 5.0g A2, the heterobifunctional chain extender 2.0g C, and the heat conductive powder surface treatment agent 2.4g D2, high-speed dispersion for 2h, control the temperature less than 60℃;

[0164] (4) Control the temperature at 20-30℃, add the hydrogen-containing polysiloxane 1.4g Bl and 0.5g B2 for dispersion for 0.5h, then add the curing inhibitor 0.05g Fl for dispersion evenly, finally add the platinum catalyst 0.15g G, mix evenly;

[0165] (5) Vacuum degassing for 10min, fill after storage at -40-0℃.

[0166] Example 4

[0167] A kind of preparation of α-vinyl-Ω-trimethoxy terminated polydimethylsiloxane, the specific preparation steps are same with example 1.

[0168] The components used in the preparation of a low hardness high resilience heat conductive silicone gel in this example 4 are same with example 3, the difference is that:

[0169] The heat conductive filler is E2 (the average particle size D 50小 is 0.6μm rod-like zinc oxide), E3 (the average particle size D 50小 is 0.8μm spherical silver powder), E5 (the average particle size D 50中 is D50 5μm spherical aluminum nitride), E8 (the average particle size D 50大 is 50μm, Dmax is 100μm spherical aluminum nitride) and E10 (the average particle size D 50大 is 50μm, Dmax is 100μm spherical diamond).

[0170] The preparation of a low hardness high resilience heat conductive silicone gel, the specific preparation steps are as follows:

[0171] (1) Put the heat conductive filler 60g E2, 20g E3, 120g E5, 160g E8 and 80g E10 into a high-speed dispersion kettle for high-speed pre-shearing;

[0172] (2) Dry pre-modification of the thermally conductive filler by adding 2.0 g of the thermally conductive powder surface treatment agent D1 by spraying for 2 h;

[0173] (3) Adding 5.0 g of the vinyl-terminated polydimethylsiloxane A1, 5.0 g of the vinyl-terminated polydimethylsiloxane A2, 2.0 g of the heterobifunctional chain extender C, and 6.0 g of the thermally conductive powder surface treatment agent D2, high-speed dispersion for 2 h, and controlling the temperature to be less than 60°C;

[0174] (4) Controlling the temperature to be 20-30°C, adding 1.4 g of the hydrogen-containing polysiloxane B1 and 0.5 g of the hydrogen-containing polysiloxane B2, and dispersing for 0.5 h, then adding 0.08 g of the cure inhibitor F1 and dispersing uniformly, and finally adding 0.2 g of the platinum catalyst G and mixing uniformly;

[0175] (5) Vacuum degassing for 10 min, and storing after filling at -40-0°C.

[0176] Example 5

[0177] Preparation of an α-vinyl-Ω-trimethoxyl-terminated polydimethylsiloxane, the specific preparation steps being the same as those in Example 1.

[0178] The components used for preparing a low-hardness high-resilience thermally conductive silicone gel in this example 5 are the same as those in Example 1, except that:

[0179] The thermally conductive filler is E2 (average particle size D 50小 of 0.6 μm rod-shaped zinc oxide), E3 (average particle size D 50小 of 0.8 μm spherical silver powder), E4 (average particle size D 50中 of 2 μm spherical aluminum nitride), E5 (average particle size D 50中 of 5 μm spherical aluminum nitride), E8 (average particle size D 50大 of 50 μm and Dmax of 100 μm spherical aluminum nitride), and E9 (average particle size D 50大 of 50 μm and Dmax of 100 μm silicon carbide powder).

[0180] The cure inhibitor is F2: tris[(1,1-dimethyl-2-propynyl)oxy]methylsilane.

[0181] Preparation of a low-hardness high-resilience thermally conductive silicone gel, the specific preparation steps being as follows:

[0182] (1) Adding 60 g of the thermally conductive filler E2, 20 g of the thermally conductive filler E3, 20 g of the thermally conductive filler E4, 100 g of the thermally conductive filler E5, 160 g of the thermally conductive filler E8, and 80 g of the thermally conductive filler E9 into a high-speed dispersion kettle for high-speed pre-shearing;

[0183] (2) Add 2.0 g of the heat-conducting powder surface treatment agent D1 by spraying to dry-premodify the heat-conducting filler for 2 h;

[0184] (3) Add 5.0 g of the vinyl-terminated polydimethylsiloxane A2, 5.0 g of the vinyl-terminated polydimethylsiloxane A3, 4.0 g of the heterobifunctional chain extender C, and 5.0 g of the heat-conducting powder surface treatment agent D2, and disperse at high speed for 2 h while controlling the temperature to be less than 60°C;

[0185] (4) Control the temperature to be 20-30°C, add 0.5 g of the hydrosilicone B1 and 0.18 g of the hydrosilicone B2, and disperse for 0.5 h, then add the curing inhibitor F2 and disperse uniformly, and finally add the platinum catalyst G, and mix uniformly;

[0186] (5) Vacuum degassing for 10 min, and store after filling at -40-0°C.

[0187] Example 6

[0188] A kind of preparation of α-vinyl-Ω-trimethoxyl terminated polydimethylsiloxane, the specific preparation steps are same with example 1.

[0189] The components used in the preparation of a low hardness and high resilience heat-conducting silicone gel in this example 6 are same with example 5, and the difference is that:

[0190] The curing inhibitor is F1: 1-ethynylcyclohexanol.

[0191] The preparation of a low hardness and high resilience heat-conducting silicone gel, and the specific preparation steps are as follows:

[0192] (1) Add the heat-conducting fillers 60 g of E2, 20 g of E3, 20 g of E4, 100 g of E5, 160 g of E8, and 80 g of E9 into a high-speed dispersion kettle for high-speed pre-shearing;

[0193] (2) Add the heat-conducting powder surface treatment agent D1 by spraying to dry-premodify the heat-conducting filler for 2 h;

[0194] (3) Add 2.0 g of the vinyl-terminated polydimethylsiloxane A2, 5.0 g of the vinyl-terminated polydimethylsiloxane A3, 8.0 g of the heterobifunctional chain extender C, and 4.5 g of the heat-conducting powder surface treatment agent D2, and disperse at high speed for 2 h while controlling the temperature to be less than 60°C;

[0195] (4) Control the temperature to be 20-30°C, add 0.4 g of the hydrosilicone B1 and 0.12 g of the hydrosilicone B2, and disperse for 0.5 h, then add the curing inhibitor F1 and disperse uniformly, and finally add the platinum catalyst G, and mix uniformly;

[0196] (5) Vacuum degassing for 10 min, and store at -40-0℃ after filling.

[0197] Example 7

[0198] A kind of α- vinyl- Ω- trimethoxyl end-capped polydimethylsiloxane, the specific preparation steps are same with example 1.

[0199] The components used in the preparation of a low hardness high resilience heat-conducting silicone gel in this example 7 are same with example 5, the difference is that: this example 7 does not add D2 (α-methyl-Ω-trimethoxyl end-capped polydimethylsiloxane).

[0200] The preparation of a low hardness high resilience heat-conducting silicone gel, the specific preparation steps are as follows:

[0201] (1) Put the heat-conducting filler 60g E2, 20g E3, 20g E4, 100g E5, 160g E8 and 80g E9 into a high-speed dispersion kettle for high-speed pre-shearing;

[0202] (2) Add 2.0g D1 of heat-conducting powder surface treatment agent by spraying method, and dry pre-modify the heat-conducting filler for 2h;

[0203] (3) Add 5.0g A2 of vinyl end-capped polydimethylsiloxane, 5.0g A3, 4.0g C of heterobifunctional chain extender, and 4.0g D1 of heat-conducting powder surface treatment agent, high-speed dispersion for 2h, control the temperature less than 60℃;

[0204] (4) Control the temperature at 20-30℃, add 0.5g B1 and 0.18g B2 of hydrogen-containing polysiloxane, disperse for 0.5h, then add 0.15g F2 of curing inhibitor, disperse uniformly, finally add 0.1g G of platinum catalyst, mix uniformly;

[0205] (5) Vacuum degassing for 10 min, and store at -40-0℃ after filling.

[0206] Comparative Example 1

[0207] A kind of α- vinyl- Ω- trimethoxyl end-capped polydimethylsiloxane, the specific preparation steps are same with example 1.

[0208] The components used in the preparation of a low hardness high resilience heat-conducting silicone gel in this example 7 are same with example 5, the difference is that: this example 7 does not add D2 (α-methyl-Ω-trimethoxyl end-capped polydimethylsiloxane).

[0209] The preparation of a low hardness high resilience heat-conducting silicone gel, the specific preparation steps are as follows:

[0210] (1) Put the heat conductive filler 60g E2, 20g E3, 20g E4, 100g E5, 160g E8 and 80g E9 into a high-speed dispersion kettle for high-speed pre-shearing;

[0211] (2) Add the heat conductive powder surface treatment agent 2.0g D1 by spraying to pre-modify the heat conductive filler by dry method for 2h;

[0212] (3) Add the vinyl-terminated polydimethylsiloxane 7.0g A2, 7.0g A3 and the heat conductive powder surface treatment agent 5g D2, high-speed dispersion for 2h, control the temperature less than 60℃;

[0213] (4) Control the temperature at 20-30℃, add the hydrogen-containing polysiloxane 0.7g B1 and 0.25g B2, disperse for 0.5h, then add the curing inhibitor 0.15g F2, disperse uniformly, finally add the platinum gold catalyst 0.1g G, mix uniformly;

[0214] (5) Vacuum degassing for 10min, fill and store at-40-0℃.

[0215] Comparative Example 2

[0216] A kind of α- vinyl-Ω-trimethoxy terminated polydimethylsiloxane is prepared, the specific preparation steps are same with Example 1.

[0217] The components used for preparing a low hardness high resilience heat conductive silicone gel in the present comparative example 2 are same with Example 5, the difference is that the present comparative example 2 does not add the heterobifunctional chain extender C (α-hydrogen-Ω-vinyl heterobifunctional terminated polydimethylsiloxane) and D1 (α-vinyl-Ω-trimethoxy terminated polydimethylsiloxane).

[0218] A low hardness high resilience heat conductive silicone gel is prepared, the specific preparation steps are as follows:

[0219] (1) Put the heat conductive filler 60g E2, 20g E3, 20g E4, 100g E5, 160g E8 and 80g E9 into a high-speed dispersion kettle for high-speed pre-shearing;

[0220] (2) Add the heat conductive powder surface treatment agent 2.0g D2 by spraying to pre-modify the heat conductive filler by dry method for 2h;

[0221] (3) Add the vinyl-terminated polydimethylsiloxane 10.0g A2, 5.0g A3 and the heat conductive powder surface treatment agent 4g D2, high-speed dispersion for 2h, control the temperature less than 60℃;

[0222] (4) Control the temperature at 20-30℃, add hydrogen-containing polysiloxane 0.7g B1 and 0.25g B2 and disperse for 0.5h, then add curing inhibitor 0.15g F2 and disperse uniformly, finally add platinum catalyst 0.1g G and mix uniformly;

[0223] (5) Vacuum degassing for 10min, and store at-40-0℃ after filling.

[0224] Comparative Example 3

[0225] A kind of α-ethenyl-Ω-trimethoxy capped polydimethylsiloxane is prepared, and the specific preparation steps are the same as those of Example 1.

[0226] The components used for preparing a low-hardness high-rebound heat-conducting silicone gel in Comparative Example 3 are the same as those of Example 5, except that Comparative Example 3 does not add bifunctional chain extender C (α-hydrogen-Ω-vinyl bifunctional capped polydimethylsiloxane) and D2 (α-methyl-Ω-trimethoxy capped polydimethylsiloxane).

[0227] A low-hardness high-rebound heat-conducting silicone gel is prepared, and the specific preparation steps are as follows:

[0228] (1) Add heat-conducting fillers 60g E2, 20g E3, 20g E4, 100g E5, 160g E8 and 80g E9 into a high-speed dispersion kettle for high-speed pre-shearing;

[0229] (2) Add heat-conducting powder surface treatment agent 2.0g D1 by spraying, and dry pre-modify the heat-conducting fillers for 2h;

[0230] (3) Add vinyl capped polydimethylsiloxane 10.0g A2, 5.0g A3 and heat-conducting powder surface treatment agent 4g D1, and disperse at high speed for 2h, with the temperature controlled below 60℃;

[0231] (4) Control the temperature at 20-30℃, add hydrogen-containing polysiloxane 0.7g B1 and 0.25g B2 and disperse for 0.5h, then add curing inhibitor 0.15g F2 and disperse uniformly, finally add platinum catalyst 0.1g G and mix uniformly;

[0232] (5) Vacuum degassing for 10min, and store at-40-0℃ after filling.

[0233] In the preparation of silicone heat-conducting gel in the examples and comparative examples of the present application, the amounts of the components are shown in Tables 1 and 2.

[0234] Comparative Example 4

[0235] A preparation of α-vinyl-Ω-trimethoxyl terminated polydimethylsiloxane, the specific preparation steps are the same as example 1.

[0236] The components for preparing a low hardness high resilience heat conductive silicone gel in the present comparative example 4 are the same as example 1, the difference is that the amount of surface treatment agent of heat conductive powder added in the present comparative example 4 is different from example 1, the amount of heat conductive powder surface treatment agent D1 (α-vinyl-Ω-trimethoxyl terminated polydimethylsiloxane) is 0.6g, the amount of D2 (α-methyl-Ω-trimethoxyl terminated polydimethylsiloxane) is 0.9g; at this time D1:D2=1:1.5, D1:D2=1:2 in example 1.

[0237] A preparation of low hardness high resilience heat conductive silicone gel, the specific preparation steps are as follows:

[0238] (1) Put 20g E1, 30g E2, 70g E4 and 120g E6 of heat conductive fillers into a high-speed dispersion kettle for high-speed pre-shearing;

[0239] (2) Add 0.6g D1 of heat conductive powder surface treatment agent by spraying method, dry pre-modification of heat conductive fillers for 2h;

[0240] (3) Add 5.0g A2, 5.0g A3 of vinyl terminated polydimethylsiloxane, 2.0g C of isobifunctional chain extender, and 0.9g D2 of heat conductive powder surface treatment agent, high-speed dispersion for 2h, control the temperature less than 60℃;

[0241] (4) Control the temperature at 20-30℃, add 0.6g B1 and 0.2g B2 of hydrogen-containing polysiloxane, disperse for 0.5h, then add 0.06g F1 of curing inhibitor, disperse uniformly, finally add 0.1g G of platinum catalyst, mix uniformly;

[0242] (5) Vacuum degassing for 10min, fill after storage at-40-0℃.

[0243] Comparative example 5

[0244] A preparation of α-vinyl-Ω-trimethoxyl terminated polydimethylsiloxane, the specific preparation steps are the same as example 1.

[0245] The components used to prepare a low-hardness high-resilience heat-conducting silicone gel in this comparative example 5 are the same as in example 1, except that the amount of heat-conducting powder surface treatment agent added in this comparative example 5 is different from that in example 1. The amount of heat-conducting powder surface treatment agent D1 (a-vinyl-Ω-trimethoxyl terminated polydimethylsiloxane) is 0.6 g, and the amount of D2 (a-methyl-Ω-trimethoxyl terminated polydimethylsiloxane) is 2.1 g. At this time, D1:D2 = 1:3.5, and in example 1, D1:D2 = 1:2.

[0246] A low-hardness high-resilience heat-conducting silicone gel is prepared, and the specific preparation steps are as follows:

[0247] (1) Add 20 g of heat-conducting filler E1, 30 g of heat-conducting filler E2, 70 g of heat-conducting filler E4, and 120 g of heat-conducting filler E6 into a high-speed dispersion kettle for high-speed pre-shearing;

[0248] (2) Add 0.6 g of heat-conducting powder surface treatment agent D1 by spraying to dry-pre-modify the heat-conducting filler for 2 h;

[0249] (3) Add 5.0 g of vinyl-terminated polydimethylsiloxane A2, 5.0 g of vinyl-terminated polydimethylsiloxane A3, 2.0 g of heterobifunctional chain extender C, and 2.1 g of heat-conducting powder surface treatment agent D2, and high-speed disperse for 2 h, with the temperature controlled to be less than 60°C;

[0250] (4) Control the temperature to be 20-30°C, add 0.6 g of hydrogen-containing polysiloxane B1 and 0.2 g of hydrogen-containing polysiloxane B2 to disperse for 0.5 h, then add 0.06 g of curing inhibitor F1 to disperse uniformly, and finally add 0.1 g of platinum catalyst G to mix uniformly;

[0251] (5) Vacuum degassing for 10 min, and store after filling at -40-0°C.

[0252] Comparative example 6

[0253] A low-hardness high-resilience heat-conducting silicone gel is prepared, and the specific preparation steps are as follows:

[0254] The components used to prepare a low-hardness high-resilience heat-conducting silicone gel in this comparative example 6 are the same as in example 1, except that the amount of heterobifunctional chain extender C (a-hydrogen-Ω-vinyl heterobifunctional terminated polydimethylsiloxane) added in this comparative example 6 is 0.48 g. At this time, D1:C = 1:0.8, and in example 1, D1:C = 1:3.33.

[0255] A low-hardness high-resilience heat-conducting silicone gel is prepared, and the specific preparation steps are as follows:

[0256] (1) Put the heat conductive filler 20g E1, 30g E2, 70g E4 and 120g E6 into a high-speed dispersion kettle for high-speed pre-shearing;

[0257] (2) Add the heat conductive powder surface treatment agent 0.6g D1 by spraying to pre-modify the heat conductive filler by dry method for 2h;

[0258] (3) Add the vinyl-terminated polydimethylsiloxane 5.0g A2, 5.0g A3, the heterobifunctional chain extender 0.48g C and the heat conductive powder surface treatment agent 1.2g D2, high-speed dispersion for 2h, control the temperature less than 60℃;

[0259] (4) Control the temperature at 20-30℃, add the hydrogen-containing polysiloxane 0.6g B1 and 0.2g B2 to disperse for 0.5h, then add the curing inhibitor 0.06g F1 to disperse uniformly, finally add the platinum gold catalyst 0.1g G to mix uniformly;

[0260] (5) Vacuum degassing for 10min, fill and store at-40-0℃.

[0261] Comparative Example 7

[0262] The preparation of an α-vinyl-Ω-trimethoxyl-terminated polydimethylsiloxane, the specific preparation steps are the same as those of Example 1.

[0263] The components used for preparing a low-hardness high-rebound heat-conductive silicone gel in Comparative Example 7 are the same as those of Example 1, the difference is that the amount of the heterobifunctional chain extender C (α-hydrogen-Ω-vinyl heterobifunctional terminated polydimethylsiloxane) added in Comparative Example 7 is 3.6g; at this time, D1:C = 1:6, and D1:C = 1:3.33 in Example 1.

[0264] The preparation of a low-hardness high-rebound heat-conductive silicone gel, the specific preparation steps are as follows:

[0265] (1) Put the heat conductive filler 20g E1, 30g E2, 70g E4 and 120g E6 into a high-speed dispersion kettle for high-speed pre-shearing;

[0266] (2) Add the heat conductive powder surface treatment agent 0.6g D1 by spraying to pre-modify the heat conductive filler by dry method for 2h;

[0267] (3) Add the vinyl-terminated polydimethylsiloxane 5.0g A2, 5.0g A3, the heterobifunctional chain extender 3.6g C and the heat conductive powder surface treatment agent 1.2g D2, high-speed dispersion for 2h, control the temperature less than 60℃;

[0268] (4) Control the temperature at 20-30℃, add hydrogen-containing polysiloxane 0.6g B1 and 0.2g B2 and disperse for 0.5h, then add curing inhibitor 0.06g F1 and disperse evenly, finally add platinum catalyst 0.1g G and mix evenly;

[0269] (5) Vacuum degassing for 10min, and store at -40-0℃ after filling.

[0270] Comparative Example 8

[0271] A kind of α- vinyl- Ω- trimethoxy capped polydimethylsiloxane is prepared, the specific preparation steps are same with example 1.

[0272] The components used for preparing a low hardness high resilience heat-conducting silicone gel in the comparative example 8 are same with example 1, the difference is that the amount of each component of the heat-conducting powder surface treatment agent added in the comparative example 8 is different from that in example 1, that is, the amount of heat-conducting powder surface treatment agent D1 (α-vinyl-Ω-trimethoxy capped polydimethylsiloxane) is 2g, and the amount of D2 (α-methyl-Ω-trimethoxy capped polydimethylsiloxane) is 4g; at this time, D1+D2=6g, and the mass ratio of heat-conducting powder surface treatment agent to heat-conducting filler is 1:40.

[0273] A low hardness high resilience heat-conducting silicone gel is prepared, and the specific preparation steps are as follows:

[0274] (1) Add heat-conducting fillers 20g E1, 30g E2, 70g E4 and 120g E6 into a high-speed dispersion kettle for high-speed pre-shearing;

[0275] (2) Add heat-conducting powder surface treatment agent 2g D1 by spraying to dryly modify the heat-conducting fillers for 2h;

[0276] (3) Add vinyl capped polydimethylsiloxane 5.0g A2, 5.0g A3, isobifunctional chain extender 2.0g C, and heat-conducting powder surface treatment agent 4g D2, and disperse at high speed for 2h while controlling the temperature below 60℃;

[0277] (4) Control the temperature at 20-30℃, add hydrogen-containing polysiloxane 0.6g B1 and 0.2g B2 and disperse for 0.5h, then add curing inhibitor 0.06g F1 and disperse evenly, finally add platinum catalyst 0.1g G and mix evenly;

[0278] (5) Vacuum degassing for 10min, and store at -40-0℃ after filling.

[0279] Comparative Example 9

[0280] A preparation of an alpha-vinyl-omega-trimethoxyl terminated polydimethylsiloxane, the specific preparation steps are the same as example 1.

[0281] The components for preparing a low-hardness high-rebound heat-conducting silicone gel in the present comparative example 8 are the same as those in example 1, except that the amounts of the components of the heat-conducting powder surface treatment agent added in the present comparative example 8 are different from those in example 1, i.e., the amount of the heat-conducting powder surface treatment agent D1 (alpha-vinyl-omega-trimethoxyl terminated polydimethylsiloxane) is 0.3 g, and the amount of the heat-conducting powder surface treatment agent D2 (alpha-methyl-omega-trimethoxyl terminated polydimethylsiloxane) is 0.7 g; at this time, D1+D2=1 g, and the mass ratio of the heat-conducting powder surface treatment agent to the heat-conducting filler is 1:240.

[0282] A preparation of a low-hardness high-rebound heat-conducting silicone gel, the specific preparation steps are as follows:

[0283] (1) The heat-conducting fillers 20 g E1, 30 g E2, 70 g E4 and 120 g E6 are added into a high-speed dispersion kettle for high-speed pre-shearing;

[0284] (2) The heat-conducting powder surface treatment agent 0.3 g D1 is added by spraying to pre-modify the heat-conducting fillers by dry method for 2 h;

[0285] (3) The vinyl terminated polydimethylsiloxane 5.0 g A2, 5.0 g A3, the heterobifunctional chain extender 2.0 g C, and the heat-conducting powder surface treatment agent 0.7 g D2 are added, and high-speed dispersion is performed for 2 h with the temperature controlled to be less than 60℃;

[0286] (4) The temperature is controlled to be 20-30℃, the hydrosilicone 0.6 g B1 and 0.2 g B2 are added and dispersed for 0.5 h, then the curing inhibitor 0.06 g F1 is added and dispersed uniformly, and finally the platinum gold catalyst 0.1 g G is added and mixed uniformly;

[0287] (5) Vacuum degassing is performed for 10 min, and the product is stored at -40-0℃ after filling.

[0288] The amounts of the components in the preparation of the silicone heat-conducting gel in the examples and comparative examples of the present application are shown in Tables 1 and 2.

[0289] Table 1 Amounts of components in the silicone heat-conducting gel in the examples

[0290]

[0291]

[0292] Table 2 Amounts of components in the silicone heat-conducting gel in the examples

[0293]

[0294]

[0295] The tests related to the heat-conducting silicone gels prepared in the examples and comparative examples of the present application are as follows:

[0296] Viscosity test: The viscosity at 5 r was measured using an Anton Paar rheometer (Anton Paar MCR302e) with a pp25 rotor.

[0297] Thermal conductivity: The thermal conductivity was measured using a HOTDISK thermal conductivity meter according to the ISO 22007-2 standard test. The thickness of the thermal conductivity sheet was 6 mm, the test was performed at 120 mW for 4 s.

[0298] Thermal resistance test: The thermal resistance was measured using a Taiwan Rui Ling thermal resistance meter LW 9389 according to the ASTM D5470 standard test. The test conditions were a temperature of 80°C and a pressure of 40 psi.

[0299] Elongation at break test: The heat-conducting silicone gel prepared was extruded on a surface-fluorinated release film, a 2 mm gap sheet was applied in the middle of the release film, and a flat plate vulcanizer was used to cure at 125°C for 60 min. Then, the elongation at break was tested according to the GB / T528 standard.

[0300] Hardness test: A 6 mm thermal conductivity sheet was prepared by using a flat plate vulcanizer to cure at 125°C for 60 min. The average hardness was obtained by measuring three times using an automatic Shore 00 hardness tester.

[0301] Storage modulus G' and G": The TA rheometer was used for testing, the test gap was 1 mm, the frequency was 1 Hz, the heat-conducting gel was applied to a 25 mm flat aluminum plate, the test temperature was 35-125°C, the temperature was raised at 5°C / min, and the temperature was kept constant for 60 min.

[0302] The ratio of G' / G" (tan δ) was calculated, which measures the resilience of the gel. When tan δ is greater than 1, the elasticity is good, and when tan δ is less than 1, the gel tends to be a viscous liquid.

[0303] The performance test data of the heat-conducting silicone gels prepared in the examples and comparative examples of the present application are shown in Table 3.

[0304] Table 3 Performance test data of heat-conducting silicone gels prepared in examples and comparative examples

[0305]

[0306]

[0307] As can be seen from Table 1 and Table 3, the heat-conducting silicone gel prepared in Examples 1-7 by the preparation method of the present application, by introducing the non-reactive heat-conductive powder surface treatment agent and the reactive heat-conductive powder surface treatment agent, balances the hardness and elasticity of the material, and improves the plasticization; at the same time, the introduction of the heterobifunctional chain extender α-hydro-Ω-vinyl heterobifunctional end-capped polydimethylsiloxane increases the polymer matrix chain entanglement, increases the material toughness, ensures that it is not easy to crack and deform, the three work together and cooperate with other components, so that the obtained heat-conducting gel further improves the heat-conducting performance, solves the problem of low hardness and high resilience of the gel. The final heat-conducting silicone gel has low hardness, high resilience and high thermal conductivity, and the thermal interface contact is more closely, which can have better heat dissipation effect.

[0308] As can be seen from the comparison of the experimental results of Example 7 and Example 5 according to the data of Table 1, Table 2 and Table 3: in Example 7, D2 (α-methyl-Ω-trimethoxyl end-capped polydimethylsiloxane) is not added, only through the joint action of the reactive heat-conductive powder surface treatment agent α-vinyl-Ω-trimethoxyl end-capped polydimethylsiloxane and the heterobifunctional chain extender α-hydro-Ω-vinyl heterobifunctional end-capped polydimethylsiloxane with each component, the final prepared heat-conducting silicone gel has high elasticity, but the hardness is high and the elongation at break decreases. Nevertheless, the material performance obtained in Example 7 is excellent, and the comprehensive performance of the heat-conducting gel obtained in Examples 1-6 is more excellent.

[0309] As can be seen from the comparison of the experimental results of Comparative Example 1 and Example 5 according to the data of Table 1, Table 2 and Table 3: in Comparative Example 1, the heterobifunctional chain extender α-hydro-Ω-vinyl heterobifunctional end-capped polydimethylsiloxane is not added, the hardness of the final obtained heat-conducting silicone gel increases, the elongation at break decreases, and the ratio of G′ / G″, tanδ, decreases, but still has a certain high elasticity. This is because, in the process of preparing the heat-conducting silicone gel, the introduction of the reactive heat-conductive powder surface treatment agent α-vinyl-Ω-trimethoxyl end-capped polydimethylsiloxane, while working together with the non-reactive heat-conductive powder surface treatment agent α-methyl-Ω-trimethoxyl end-capped polydimethylsiloxane, can alleviate the plasticization of the heat-conducting silicone gel, and give the material a certain high elasticity, while also improving the hardness of the material; but without the heterobifunctional chain extender α-hydro-Ω-vinyl heterobifunctional end-capped polydimethylsiloxane, the entanglement degree between the polymer matrixes is low, which makes the elasticity decrease, the elongation at break decrease, the gel crack and deform when stretched, and further lead to the decrease of the toughness of the material.

[0310] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 2 and Example 5 that: Comparative Example 2 does not introduce the heterobifunctional chain extender a-hydro-Ω-vinyl heterobifunctional end-capped polydimethylsiloxane and the reactive thermal conductive powder surface treatment agent a-vinyl-Ω-trimethoxyl end-capped polydimethylsiloxane, but only introduces the non-reactive thermal conductive powder surface treatment agent, and the breaking elongation and the ratio of G' to G", tan delta, of the final thermal conductive silicone gel are significantly reduced, and the material is not elastic but tends to be a viscous liquid. This is because the non-reactive thermal conductive powder surface treatment agent physically modifies the thermal conductive filler, which can to some extent alleviate the plasticization of the material, but cannot endow the material with high elasticity and cannot enhance the chain entanglement ability between the material matrix.

[0311] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 3 and Example 5 that: Comparative Example 3 does not introduce the heterobifunctional chain extender a-hydro-Ω-vinyl heterobifunctional end-capped polydimethylsiloxane and the non-reactive thermal conductive powder surface treatment agent a-methyl-Ω-trimethoxyl end-capped polydimethylsiloxane, but only introduces the reactive thermal conductive powder surface treatment agent a-vinyl-Ω-trimethoxyl end-capped polydimethylsiloxane, and the hardness of the final thermal conductive silicone gel increases, the breaking elongation decreases, and the ratio of G' to G", tan delta, decreases, and the material has a certain elasticity but insufficient toughness, and is too hard to crack and deform. This is because the addition of the reactive thermal conductive powder surface treatment agent can endow the material with a certain elasticity, but cannot well improve the problem of too hard and insufficient toughness of the material.

[0312] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 4 and Example 1 that: in Comparative Example 4, the amount of the thermal conductive powder surface treatment agent D1:D2=1:1.5, and the obtained thermal conductive gel is hard and the breaking elongation decreases. This is because the amount of the reactive thermal conductive powder surface treatment agent in Comparative Example 4 is too much, and the reactive thermal conductive powder treatment agent participates in the crosslinking network, and the chain entanglement ratio is high, so that the final obtained thermal conductive gel is hard and the breaking elongation decreases.

[0313] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 5 and Example 1 that: in Comparative Example 5, the amount of the thermal conductive powder surface treatment agent D1:D2=1:3, and the obtained thermal conductive gel has decreased elasticity, low hardness and decreased breaking elongation. This is because the amount of the non-reactive thermal conductive powder surface treatment agent in Comparative Example 5 is too much, and after interacting with the reactive thermal conductive powder surface treatment agent and other components, the material is too soft to maintain better elasticity.

[0314] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 6 and Example 1 that: in Comparative Example 6, the amount of heterobifunctional chain extender C (α-hydro-Ω-vinyl heterobifunctional terminated polydimethylsiloxane) is reduced, so that D1:C = 1:0.8, and the final obtained thermal conductive gel hardness is low and the elongation at break decreases. This is because, in Comparative Example 6, the amount of heterobifunctional chain extender is insufficient, and after the components are combined, the chain entanglement ability between the material matrix is weakened, thereby resulting in low material hardness and decreased elongation at break.

[0315] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 7 and Example 1 that: in Comparative Example 6, the amount of heterobifunctional chain extender C (α-hydro-Ω-vinyl heterobifunctional terminated polydimethylsiloxane) is increased, so that D1:C = 1:6, and the final obtained thermal conductive gel hardness is low, the elongation at break increases, and the resilience is poor. This is because, in Comparative Example 6, the amount of heterobifunctional chain extender is excessive, and the crosslinked polymer proportion is low. Although C can increase the chain entanglement proportion and improve the resilience, the excessive C cannot offset the amount of AB component vinyl terminated polydimethylsiloxane and hydrogen-containing polysiloxane crosslinking to cause hardness to decrease, thereby resulting in poor resilience.

[0316] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 8 and Example 1 that: in Comparative Example 8, when the mass ratio of thermal conductive powder surface treatment agent to thermal conductive filler is 1:40, the final obtained thermal conductive silicone gel has decreased elasticity, decreased thermal conductivity, and poor resilience. This is because, when the mass ratio of thermal conductive powder surface treatment agent to thermal conductive filler is 1:40, the amount of thermal conductive powder surface treatment agent is excessive and the amount of thermal conductive filler is low, the thermal conductivity is low, the amount of thermal conductive powder treatment agent is excessive, which acts as a diluent, the crosslinking system proportion decreases, the plasticizing effect increases, the thermal conductive gel hardness is low, and the resilience is poor.

[0317] According to the data in Table 1, Table 2 and Table 3, it can be seen from the comparison of the experimental results of Comparative Example 9 and Example 1 that: in Comparative Example 9, when the mass ratio of thermal conductive powder surface treatment agent to thermal conductive filler is 1:240, the final obtained thermal conductive silicone gel has no elasticity, high hardness, and decreased elongation at break. This is because, when the mass ratio of thermal conductive powder surface treatment agent to thermal conductive filler is 1:240, the amount of thermal conductive powder surface treatment agent is insufficient, and the modification of the thermal conductive powder surface treatment agent is insufficient, thereby affecting the performance of the final obtained thermal conductive silicone gel.

[0318] The technical features of the above-described embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments are enumerated, and it should be understood that any combination of the technical features is within the scope of the present disclosure as long as the combination does not result in a contradiction.

[0319] As is apparent from the foregoing, a number of changes and modifications can be made to the present application without departing from the underlying inventive concepts disclosed above. Such changes and modifications are to be understood as coming within the scope of the present application as defined by the appended claims.

Claims

1. A low-hardness, high-resilience, thermally conductive silicone gel, characterized in that: The organic silicone gel is composed of the following components: vinyl-terminated polydimethylsiloxane, hydrogen-containing polysiloxane, heterobifunctional chain extender, thermal conductive powder surface treatment agent, thermal conductive filler, curing inhibitor, and platinum catalyst; Among them, the components are calculated by mass fraction: the content of vinyl-terminated polydimethylsiloxane is 2-10wt%, the content of hydrogen-containing polysiloxane is 0.2-1wt%, the content of heterobifunctional chain extender is 1-5wt%, the content of thermal conductive powder surface treatment agent is 0.5-2.5wt%, the addition amount of curing inhibitor is 50-800ppm, the addition amount of platinum catalyst is 1-5ppm, and the thermal conductive filler is the balance.

2. The low-hardness, high-resilience, thermally conductive silicone gel according to claim 1, characterized in that: The vinyl terminated polydimethylsiloxane is at least one having a viscosity in the range of 50-1000 mPa.s at 25°C; The hydrogen-containing polysiloxane includes terminal hydrogen silicone oil and side hydrogen silicone oil, wherein the terminal hydrogen silicone oil contains silicon-hydrogen bonds at both ends of the molecule, and the side hydrogen silicone oil contains silicon-hydrogen bonds in the side chain of the molecule; The thermally conductive filler includes aluminum nitride, silicon carbide, diamond, zinc oxide, aluminum oxide and silver powder; The curing inhibitor is an acetylenic alcohol inhibitor; The platinum catalyst is a Custer platinum catalyst.

3. The low-hardness, high-resilience, thermally conductive silicone gel according to claim 2, characterized in that: The vinyl terminated polydimethylsiloxane is at least one of a viscosity range of 50-500 mPa.s at 25° C. and a vinyl content of 0.4-1.8 wt %; The hydrogen-terminated silicone oil has a viscosity of 5-50 mPa.s, and a hydrogen content of 0.02-0.2 wt%; the side hydrogen-containing silicone oil has a viscosity of 50-1500 mPa.s, and a hydrogen content of 0.05-0.12 wt%; The ratio of hydrogen content in the hydrogen-terminated silicone oil to that in the side hydrogen-containing silicone oil is (2-10):

1.

4. The low-hardness, high-resilience, thermally conductive silicone gel according to claim 2, characterized in that: Thermal conductive fillers include large particle size thermal conductive fillers, medium particle size thermal conductive fillers and small particle size thermal conductive fillers; The large-particle thermal conductive filler has an average particle size D 50大 At least one of aluminum nitride, silicon carbide and diamond with a diameter of 30-50 μm; The medium-sized thermal conductive filler has an average particle size D 50中 At least one of spherical alumina, quasi-spherical alumina and single-crystal alumina with a diameter of 2-5 μm; The small-particle thermal conductive filler has an average particle size D 50小 At least one of zinc oxide, aluminum oxide and spherical silver powder with a diameter of 0.3-1 μm; Among them, the largest particle size D max and average particle size D 50大 The relationship is: D 50大 ≤D max ≤2D 50大 .

5. The low-hardness, high-resilience, thermally conductive organic silicone gel according to claim 1, characterized in that: The heterobifunctional chain extender is α-hydrogen-Ω vinyl heterobifunctional terminated polydimethylsiloxane; The thermally conductive powder surface treatment agent is at least one of a reactive thermally conductive powder surface treatment agent and a non-reactive thermally conductive powder surface treatment agent; The reactive thermally conductive powder surface treatment agent is α-vinyl-Ω-trimethoxy-terminated polydimethylsiloxane, and its chemical structure is: Wherein, n is 5-30; The non-reactive thermally conductive powder surface treatment agent is α-methyl-Ω-trimethoxy-terminated polydimethylsiloxane.

6. The low-hardness, high-resilience, thermally conductive silicone gel according to claim 5, characterized in that: The thermally conductive powder surface treatment agent is a mixture of a reactive thermally conductive powder surface treatment agent and a non-reactive thermally conductive powder surface treatment agent, wherein the mass ratio of the reactive thermally conductive powder surface treatment agent, the non-reactive thermally conductive powder surface treatment agent and the heterobifunctional chain extender is 1:(2-3):(1-5.5).

7. The low-hardness, high-resilience, thermally conductive silicone gel according to claim 1, characterized in that: The mass ratio of the thermally conductive powder surface treatment agent to the thermally conductive filler is 1:(50-200).

8. The low-hardness, high-resilience, thermally conductive organic silicone gel according to any one of claims 1 to 7, characterized in that: The preparation method of the reactive thermally conductive powder surface treatment agent comprises the following steps: S1. Slowly add n-butyl lithium to tetravinyl tin under an inert gas at -40°C to -78°C to react and obtain a vinyl lithium initiator reaction solution; S2. Under inert gas, hexamethylcyclotrisiloxane is refluxed to remove water, and then a polar accelerator is added and stirred to obtain a mixed solution; S3, under inert gas, introducing the vinyl lithium initiator reaction solution in step S1 into the mixed solution in step S2, and adding trimethoxysilyl chloride to react; S4. Add an adsorbent to remove impurity salts to obtain a thermally conductive powder surface treatment agent, namely, α-vinyl-Ω-trimethoxy-terminated polydimethylsiloxane.

9. The low-hardness, high-resilience, thermally conductive silicone gel according to claim 8, characterized in that: In step S1, the molar ratio of the n-butyl lithium to the tetravinyl tin is 1:4; In step S2, the polar promoter is at least one of tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide; In step S3, the molar ratio of vinyl lithium initiator, hexamethylcyclotrisiloxane and trimethoxychlorosilane is 1:(2-10):(1.01-1.1).

10. A method for preparing a low-hardness, high-resilience, thermally conductive silicone gel according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) Adding thermal conductive filler into a high-speed dispersion kettle for high-speed pre-shearing; (2) adding a portion of the thermal conductive powder surface treatment agent by spraying to perform dry pre-modification on the thermal conductive filler; (3) Add vinyl-terminated polydimethylsiloxane, heterobifunctional chain extender, and another portion of thermal conductive powder surface treatment agent and stir evenly; (4) adding hydrogenated polysiloxane, curing inhibitor and platinum catalyst in sequence and mixing them evenly; (5) Vacuum degassing and store at -40-0℃ after filling.

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