Heat-conducting adhesive as well as preparation method and application thereof

Abstract

The invention provides a heat-conducting adhesive as well as a preparation method and application thereof, and the heat-conducting adhesive comprises the following components in parts by weight: 12-20 parts of organic silicone oil, 2-5 parts of hyperbranched polyborosiloxane, 1-3 parts of a powder treating agent, 0.32-0.4 part of a catalyst and 178-182 parts of heat-conducting powder. The heat-conducting adhesive provided by the invention comprises the organic silicone oil, the hyperbranched polyborosiloxane, the powder treating agent and the heat-conducting powder which are matched with one another, and particularly, the hyperbranched polyborosiloxane and the heat-conducting powder are introduced, so that the heat-conducting adhesive has high bonding strength, high heat conductivity and low viscosity at the same time; therefore, the LED lamp has good heat dissipation capability and operability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of adhesives, and relates to a heat-conducting adhesive as well as a preparation method and application thereof, in particular to a high-adhesion heat-conducting adhesive with low viscosity as well as a preparation method and application thereof. BACKGROUND

[0002] With the development of electronic devices towards high integration and high power density, if the heat generated by the devices during operation cannot be dissipated in time and effectively, the performance of the devices will be reduced or even failure. Therefore, the heat-conducting adhesive with high thermal conductivity and good adhesion performance is widely concerned in optical modules, chip packaging and power device heat dissipation. At present, the commonly used heat-conducting adhesives are mostly based on polydimethylsiloxane, epoxy resin or polyurethane as the matrix, and filled with high-thermal-conductivity fillers such as aluminum oxide, boron nitride and silver powder to improve the thermal conductivity.

[0003] However, the existing technology generally faces the following three problems: first, high thermal conductivity usually depends on a high volume fraction of fillers (> 80wt%), which significantly increases the viscosity of the system, reduces the flowability and processability, and is not conducive to automatic dispensing and thin layer coating. Second, the interface compatibility between the polymer matrix and the inorganic filler is poor, and the interface thermal resistance is large, which limits the effective thermal conduction channel. Third, the traditional heat-conducting adhesives mostly emphasize the improvement of thermal conductivity, but the adhesion strength is limited, which is difficult to meet the requirements of interface reliability and thermal cycle resistance during long-period operation of the devices.

[0004] Therefore, it is desirable in the art to develop a heat-conducting adhesive which has low viscosity, high adhesion and high thermal conductivity. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a heat-conducting adhesive as well as a preparation method and application thereof, in particular to a high-adhesion heat-conducting adhesive with low viscosity as well as a preparation method and application thereof. The present application mixes silicone oil, hyperbranched polyborosiloxane and heat-conducting powder, the hyperbranched polyborosiloxane with multiple reaction functional groups enhances the interface adhesion, and the heat-conducting powder with particle size grading relationship realizes the improvement of thermal conductivity and the reduction of viscosity. The heat-conducting adhesive provided by the present application can effectively solve the contradiction between high thermal conductivity, high adhesion and low viscosity.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a heat-conducting adhesive, which comprises the following components in parts by weight: 12-20 parts of silicone oil, 2-5 parts of hyperbranched polyborosiloxane, 1-3 parts of powder treatment agent, 0.32-0.4 parts of catalyst and 178-182 parts of heat-conducting powder.

[0008] The heat-conducting adhesive provided by the application comprises silicone oil, hyperbranched polysiloxane, powder treatment agent and heat-conducting powder, and each component cooperates with each other, especially the introduction of hyperbranched polysiloxane and heat-conducting powder, so that the heat-conducting adhesive has high bonding strength, high thermal conductivity and low viscosity at the same time, and has good heat dissipation capacity and operability.

[0009] In the application, the amount of silicone oil in the heat-conducting adhesive can be 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc., the amount of hyperbranched polysiloxane can be 2 parts, 2.2 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.5 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.5 parts, 4.6 parts, 4.8 parts, 5 parts, etc., the amount of powder treatment agent can be 1 part, 1.2 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.8 parts, 3 parts, etc., the amount of catalyst can be 0.32 parts, 0.33 parts, 0.34 parts, 0.35 parts, 0.36 parts, 0.37 parts, 0.38 parts, 0.39 parts, 0.4 parts, etc., and the amount of heat-conducting powder can be 178 parts, 179 parts, 180 parts, 181 parts, 182 parts, etc.

[0010] Preferably, the hyperbranched polysiloxane is prepared by the following method:

[0011] 4-bromophenylboronic acid, 3-aminopropyl triethoxysilane, an organic solvent and water are mixed, stirred, then a catalyst is added, reacted, and post-treated to obtain the hyperbranched polysiloxane.

[0012] Preferably, the molar ratio of 4-bromophenylboronic acid to 3-aminopropyl triethoxysilane is 1:(0.8-1.2), for example 1:0.8, 1:0.9, 1:1, 1:1.1, 1.2, etc.

[0013] Preferably, the organic solvent comprises ethanol.

[0014] Preferably, the volume ratio of the organic solvent to water is (5-8):1, for example 5:1, 6:1, 7:1, 8:1, etc.

[0015] Preferably, the stirring speed is 600-1000 rpm, for example 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, etc., and the stirring time is 10-20 min, for example 10 min, 15 min, 20 min, etc.

[0016] Preferably, the mass ratio of the 3-aminopropyltriethoxysilane to water is (10-12):1, such as 10:1, 10.5:1, 11:1, 11.5:1, 12:1, etc.

[0017] Preferably, the stirring is performed under inert gas protection.

[0018] Preferably, the inert gas comprises nitrogen.

[0019] Preferably, the catalyst comprises triethylamine.

[0020] Preferably, the temperature of the reaction is 50-70°C, such as 50°C, 55°C, 60°C, 65°C, 70°C, etc., and the time of the reaction is 20-30h, such as 20h, 24h, 28h, 30h, etc.

[0021] Preferably, the post-treatment comprises vacuum rotary evaporation.

[0022] Preferably, the silicone oil comprises any one or a combination of at least two of a vinyl silicone oil, an amino silicone oil, an epoxy silicone oil, a methyl phenyl silicone oil, a hydroxyl silicone oil, preferably an amino silicone oil and / or an epoxy silicone oil.

[0023] Preferably, the silicone oil comprises a mixture of the amino silicone oil and the epoxy silicone oil in a mass ratio of 1:(1-2) (such as 1:1, 1:1.5, 1:2, etc.).

[0024] Preferably, the viscosity of the amino silicone oil at 25°C is 50-60mm 2 / s, such as 50mm 2 / s, 55mm 2 / s, 60mm 2 / s, etc.

[0025] Preferably, the viscosity of the epoxy silicone oil at 25°C is 30-40mm 2 / s, such as 30mm 2 / s, 35mm 2 / s, 40mm 2 / s, etc.

[0026] Preferably, the powder treatment agent comprises any one or a combination of at least two of an amino silane coupling agent, a sulfur-containing silane coupling agent, an epoxy silane coupling agent, a vinyl silane coupling agent, an alkane silane coupling agent, preferably an alkane silane coupling agent.

[0027] Preferably, the alkane silane coupling agent comprises a mono-terminal trimethoxysilane-terminated polydimethylsilane.

[0028] Preferably, the catalyst comprises 2-ethyl-4-methylimidazole.

[0029] Preferably, the thermally conductive powder comprises any one or a combination of at least two of aluminum powder, silver powder, aluminum oxide, aluminum nitride, magnesium oxide, zinc oxide, boron nitride, preferably aluminum powder and / or aluminum oxide.

[0030] Preferably, the aluminum oxide comprises spherical aluminum oxide with an average particle size of 0.2-0.8 μm (e.g. 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, etc.), preferably spherical aluminum oxide with an average particle size of 0.5 μm.

[0031] Preferably, the aluminum powder comprises spherical aluminum powder with an average particle size of 1-30 μm (e.g. 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.), preferably spherical aluminum powder with an average particle size of 3-25 μm.

[0032] Preferably, the aluminum powder comprises spherical aluminum powder with an average particle size of 20.5 μm and spherical aluminum powder with an average particle size of 5.4 μm.

[0033] Preferably, the thermally conductive powder comprises one or at least two of the following powders:

[0034] a single-particle-size thermally conductive powder composed of spherical aluminum powder with an average particle size of 20.5 μm;

[0035] a binary-compound thermally conductive powder composed of spherical aluminum powder with an average particle size of 20.5 μm and spherical aluminum powder with an average particle size of 5.4 μm, with a mass ratio of (1-3):1, e.g. 1:1, 1.5:1, 2:1, 2.5:1, 3:1, etc.;

[0036] a ternary-compound thermally conductive powder composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical aluminum oxide with an average particle size of 0.5 μm, with a mass ratio of (5-7):(2-4):1, 5-7 e.g. can be 5, 5.5, 6, 6.5, 7, etc., 2-4 e.g. can be 2, 2.5, 3, 3.5, 4, etc.

[0037] In a second aspect, the present application provides a preparation method of the thermally conductive adhesive as described in the first aspect, the preparation method comprising the following steps:

[0038] mixing the silicone oil and the powder treatment agent for the first time, then adding the hyperbranched polysiloxane and the thermally conductive powder for the second time, and then adding the catalyst for the third time, and curing to obtain the thermally conductive adhesive.

[0039] Preferably, the thermally conductive powder is subjected to a drying treatment before use.

[0040] Preferably, the temperature of the drying is 110-130℃, such as 110℃, 115℃, 120℃, 125℃, 130℃, etc., and the time of the drying is 20-30h, such as 20h, 25h, 30h, etc.

[0041] Preferably, the rotating speed of the first mixing is 700-900rpm, such as 700rpm, 750rpm, 800rpm, 850rpm, 900rpm, etc., and the time of the first mixing is 4-6min, such as 4min, 4.5min, 5min, 5.5min, 6min, etc.

[0042] Preferably, the rotating speed of the second mixing is 1400-1600rpm, such as 1400rpm, 1450rpm, 1500rpm, 1550rpm, 1600rpm, etc., and the time of the second mixing is 10-20min, such as 10min, 15min, 20min, etc.

[0043] Preferably, the rotating speed of the third mixing is 800-1200rpm, such as 800rpm, 900rpm, 1000rpm, 1100rpm, 1200rpm, etc., and the time of the third mixing is 3-8min, such as 3min, 5min, 6min, 8min, etc.

[0044] Preferably, the solidifying is solidifying by stepwise temperature rising, including: firstly solidifying at 80-120℃ (such as 80℃, 90℃, 100℃, 110℃, 120℃, etc.) for 20-40min (such as 20min, 25min, 30min, 35min, 40min, etc.), then solidifying at 110-130℃ (such as 110℃, 115℃, 120℃, 125℃, 130℃, etc.) for 50-70min (such as 50min, 55min, 60min, 65min, 70min, etc.), and finally solidifying at 140-160℃ (such as 140℃, 145℃, 150℃, 155℃, 160℃, etc.) for 110-130min (such as 110min, 115min, 120min, 125min, 130min, etc.).

[0045] In a third aspect, the present application provides an application of the heat-conducting adhesive as described in the first aspect in electronic devices.

[0046] Compared with the prior art, the present application has at least the following beneficial effects:

[0047] The heat-conducting adhesive provided by the present application comprises silicone oil, hyperbranched polysiloxane, powder treatment agent and heat-conducting powder, and each component cooperates with each other, especially the introduction of hyperbranched polysiloxane and heat-conducting powder, so that the heat-conducting adhesive has high bonding strength, high thermal conductivity and low viscosity at the same time, and has good heat dissipation capacity and operability. DETAILED DESCRIPTION

[0048] The technical solutions of the present application are further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0049] Preparation Example 1

[0050] In the present preparation example, a hyperbranched polysiloxane is provided, and the preparation method comprises the following steps:

[0051] 4-bromophenylboronic acid and 3-aminopropyl triethoxysilane are added into a mixture of ethanol and water, stirred at 800 rpm for 15 min under nitrogen atmosphere, then a catalyst (triethylamine) is added, and reacted in an oil bath at 60℃ for 24 h, and vacuum rotary evaporation is performed to obtain the hyperbranched polysiloxane;

[0052] The molar ratio of 4-bromophenylboronic acid and 3-aminopropyl triethoxysilane is 1:1, the volume ratio of ethanol and water is 6:1, and the mass ratio of 3-aminopropyl triethoxysilane to water is 11.07:1.

[0053] Unless otherwise specified, the following examples and comparative examples of the present application use the following information of some raw materials:

[0054] Monoterminal trimethoxysilane-terminated polydimethylsilane: FM-0815J;

[0055] Hyperbranched polysiloxane: provided in Preparation Example 1;

[0056] Catalyst: 2-ethyl-4-methylimidazole.

[0057] Example 1

[0058] In the present example, a heat-conducting adhesive is provided, which comprises the following components in terms of weight fraction:

[0059] 16 parts of silicone oil, 2 parts of monoterminal trimethoxysilane-terminated polydimethylsilane, 4 parts of hyperbranched polysiloxane, 0.4 parts of catalyst, and 178 parts of ternary compounded heat-conducting powder.

[0060] The silicone oil has a viscosity of 55 mm 2 / s (25℃) and a viscosity of 35 mm 2epoxy silicone oil with viscosity of 55 mm / s (25℃) and epoxy silicone oil with viscosity of 35 mm / s (25℃) in a mass ratio of 1:1.8; the ternary compounded thermal conductive powder is composed of spherical aluminum powder with average particle size of 20.5 μm, spherical aluminum powder with average particle size of 5.4 μm and spherical aluminum oxide with average particle size of 0.5 μm in a mass ratio of 6:3:1.

[0061] The preparation method of the thermal conductive adhesive comprises the following steps:

[0062] (1) 178 parts of the ternary compounded thermal conductive powder are placed in a vacuum drying box at 120℃ for 24h, and then naturally cooled to 25℃ for standby.

[0063] (2) 2 parts of monoterminated trimethoxysilane-terminated polydimethylsilane and 16 parts of silicone oil are added into a planetary mixer for stirring at a speed of 800 rpm for 5 min. Then 4 parts of hyperbranched polyborosiloxane and 178 parts of the ternary compounded thermal conductive powder are added into the planetary mixer for stirring at a speed of 1500 rpm for 15 min. Then, 0.4 parts of catalyst is added and mixed at a speed of 1000 rpm for 5 min. Finally, the material is cured by ladder heating, and the specific curing procedure is: first cured at 100℃ for 30 min, then cured at 120℃ for 60 min, and finally cured at 150℃ for 120 min.

[0064] Example 2

[0065] In this example, a thermal conductive adhesive is provided, which comprises the following components in parts by weight:

[0066] 14 parts of silicone oil, 2 parts of monoterminated trimethoxysilane-terminated polydimethylsilane, 4 parts of hyperbranched polyborosiloxane, 0.36 parts of catalyst, 180 parts of ternary compounded thermal conductive powder.

[0067] The silicone oil has a viscosity of 55 mm / s (25℃) and the amino silicone oil has a viscosity of 35 mm / s (25℃). 2 The silicone oil has a viscosity of 55 mm / s (25℃) and the amino silicone oil has a viscosity of 35 mm / s (25℃). 2 epoxy silicone oil with viscosity of 55 mm / s (25℃) and epoxy silicone oil with viscosity of 35 mm / s (25℃) in a mass ratio of 1:1.8; the ternary compounded thermal conductive powder is composed of spherical aluminum powder with average particle size of 20.5 μm, spherical aluminum powder with average particle size of 5.4 μm and spherical aluminum oxide with average particle size of 0.5 μm in a mass ratio of 6:3:1.

[0068] The preparation method of the thermal conductive adhesive comprises the following steps:

[0069] (1) 180 parts of the ternary compounded thermal conductive powder are placed in a vacuum drying box at 120℃ for 24h, and then naturally cooled to 25℃ for standby.

[0070] (2) Put 2 parts of mono-terminal trimethoxysilane terminated polydimethylsilane and 14 parts of silicone oil into a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 4 parts of hyperbranched polyborosiloxane and 180 parts of ternary compounded thermal conductive powder into the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.36 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, the material is cured by step-up temperature, and the specific curing procedure is: first cured at 100°C for 30 min, then cured at 120°C for 60 min, and finally cured at 150°C for 120 min.

[0071] Example 3

[0072] In this example, a thermal conductive adhesive is provided, which comprises the following components in parts by weight:

[0073] 12 parts of silicone oil, 2 parts of mono-terminal trimethoxysilane terminated polydimethylsilane, 4 parts of hyperbranched polyborosiloxane, 0.32 parts of catalyst, 182 parts of ternary compounded thermal conductive powder.

[0074] The silicone oil has a viscosity of 55 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm

[0075] The preparation method of the thermal conductive adhesive comprises the following steps:

[0076] (1) Put 182 parts of ternary compounded thermal conductive powder into a 120°C vacuum drying oven for 24 h, and then naturally cool to 25°C for standby.

[0077] (2) Put 2 parts of mono-terminal trimethoxysilane terminated polydimethylsilane and 12 parts of silicone oil into a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 4 parts of hyperbranched polyborosiloxane and 182 parts of ternary compounded thermal conductive powder into the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.32 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, the material is cured by step-up temperature, and the specific curing procedure is: first cured at 100°C for 30 min, then cured at 120°C for 60 min, and finally cured at 150°C for 120 min.

[0078] Example 4

[0079] In this embodiment, a heat-conducting adhesive is provided, which comprises the following components in parts by weight:

[0080] 16 parts of silicone oil, 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane, 2 parts of hyperbranched polyborosiloxane, 0.4 parts of catalyst, 178 parts of ternary compounded heat-conducting powder.

[0081] The silicone oil has a viscosity of 55 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm 2 The ternary compounded heat-conducting powder is composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical aluminum oxide with an average particle size of 0.5 μm, and the mass ratio is 6:3:1.

[0082] The preparation method of the heat-conducting adhesive comprises the following steps:

[0083] (1) Place 178 parts of ternary compounded heat-conducting powder in a 120°C vacuum drying oven for 24 h, and then naturally cool to 25°C for standby.

[0084] (2) Add 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane and 16 parts of silicone oil to a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 2 parts of hyperbranched polyborosiloxane and 178 parts of ternary compounded heat-conducting powder to the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.4 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, the material is cured by stepwise heating, and the specific curing program is: first cured at 100°C for 30 min, then cured at 120°C for 60 min, and then cured at 150°C for 120 min.

[0085] Example 5

[0086] In this embodiment, a heat-conducting adhesive is provided, which comprises the following components in parts by weight:

[0087] 16 parts of silicone oil, 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane, 4 parts of hyperbranched polyborosiloxane, 0.4 parts of catalyst, 178 parts of ternary compounded heat-conducting powder.

[0088] The silicone oil has a viscosity of 55 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm 2 The ternary compounded heat-conducting powder is composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical aluminum oxide with an average particle size of 0.5 μm, and the mass ratio is 6:3:1.

[0082] The preparation method of the heat-conducting adhesive comprises the following steps:

[0083] (1) Place 178 parts of ternary compounded heat-conducting powder in a 120°C vacuum drying oven for 24 h, and then naturally cool to 25°C for standby.

[0084] (2) Add 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane and 16 parts of silicone oil to a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 2 parts of hyperbranched polyborosiloxane and 178 parts of ternary compounded heat-conducting powder to the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.4 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, the material is cured by stepwise heating, and the specific curing program is: first cured at 100°C for 30 min, then cured at 120°C for 60 min, and then cured at 150°C for 120 min.

[0085] Example 5

[0086] In this embodiment, a heat-conducting adhesive is provided, which comprises the following components in parts by weight:

[0087] 16 parts of silicone oil, 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane, 4 parts of hyperbranched polyborosiloxane, 0.4 parts of catalyst, 178 parts of ternary compounded heat-conducting powder.

[0088] The silicone oil has a viscosity of 55 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm 2 The ternary compounded heat-conducting powder is composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical aluminum oxide with an average particle size of 0.5 μm, and the mass ratio is 6:3:1.

[0082] The preparation method of the heat-conducting adhesive comprises the following steps:

[0083] (1) Place 178 parts of ternary compounded heat-conducting powder in a 120°C vacuum drying oven for 24 h, and then naturally cool to 25°C for standby.

[0084] (2) Add 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane and 16 parts of silicone oil to a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 2 parts of hyperbranched polyborosiloxane and 178 parts of ternary compounded heat-conducting powder to the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.4 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, the material is cured by stepwise heating, and the specific curing program is: first cured at 100°C for 30 min, then cured at 120°C for 60 min, and then cured at 150°C for 120 min.

[0085] Example 5

[0086] In this embodiment, a heat-conducting adhesive is provided, which comprises the following components in parts by weight:

[0087] 16 parts of silicone oil, 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane, 4 parts of hyperbranched polyborosiloxane, 0.4 parts of catalyst, 178 parts of ternary compounded heat-conducting powder.

[0088] The silicone oil has a viscosity of 55 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm 2 The ternary compounded heat-conducting powder is composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical aluminum oxide with an average particle size of 0.5 μm, and the mass ratio is 6:3:1.

[0082] The preparation method of the heat-conducting adhesive comprises the following steps:

[0083] (1) Place 178 parts of ternary compounded heat-conducting powder in a 120°C vacuum drying oven for 24 h, and then naturally cool to 25°C for standby.

[0084] (2) Add 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane and 16 parts of silicone oil to a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 2 parts of hyperbranched polyborosiloxane and 178 parts of ternary compounded heat-conducting powder to the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.4 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, the material is cured by stepwise heating, and the specific curing program is: first cured at 100°C for 30 min, then cured at 120°C for 60 min, and thenepoxy silicone oil with a viscosity of 55 mm

[0089] The preparation method of the heat-conducting adhesive comprises the following steps:

[0090] (1) 178 parts of the binary compounded heat-conducting powder are placed in a vacuum drying box at 120°C for 24 hours, and then naturally cooled to 25°C for standby.

[0091] (2) 2 parts of monoterminated trimethoxysilane-terminated polydimethylsilane and 16 parts of silicone oil are added into a planetary mixer and stirred at a speed of 800 rpm for 5 minutes. Then 4 parts of hyperbranched polyborosiloxane and 178 parts of the binary compounded heat-conducting powder are added into the planetary mixer and stirred at a speed of 1500 rpm for 15 minutes. Then, 0.4 parts of the catalyst is added and mixed at a speed of 1000 rpm for 5 minutes. Finally, the material is cured by stepwise temperature rising, and the specific curing procedure is as follows: first cured at 100°C for 30 minutes, then cured at 120°C for 60 minutes, and finally cured at 150°C for 120 minutes.

[0092] Example 6

[0093] In this example, a heat-conducting adhesive is provided, which comprises the following components in terms of weight fraction:

[0094] 16 parts of silicone oil, 2 parts of monoterminated trimethoxysilane-terminated polydimethylsilane, 4 parts of hyperbranched polyborosiloxane, 0.4 parts of catalyst, and 178 parts of single-particle-size heat-conducting powder.

[0095] The silicone oil has a viscosity of 55 mm 2 The amino silicone oil has a viscosity of 35 mm 2 The epoxy silicone oil has a viscosity of 55 mm

[0096] The preparation method of the heat-conducting adhesive comprises the following steps:

[0097] (1) 178 parts of the binary compounded heat-conducting powder are placed in a vacuum drying box at 120°C for 24 hours, and then naturally cooled to 25°C for standby.

[0098] (2) Put 2 parts of monofunctional trimethoxysilane-terminated polydimethylsilane and 16 parts of silicone oil into a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 4 parts of hyperbranched polysilaborane and 178 parts of single-size heat-conducting powder into the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.4 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, cure the material by stepwise temperature increase, and the specific curing procedure is: first cure at 100°C for 30 min, then cure at 120°C for 60 min, and finally cure at 150°C for 120 min.

[0099] Comparative Example 1

[0100] In this comparative example, a heat-conducting adhesive is provided, which comprises the following components in parts by weight:

[0101] 20 parts of silicone oil, 2 parts of monofunctional trimethoxysilane-terminated polydimethylsilane, 0.4 parts of catalyst, and 178 parts of ternary compounded heat-conducting powder.

[0102] The silicone oil has a viscosity of 55 mm 2 / s (25°C) and a viscosity of 35 mm 2 / s (25°C) and a viscosity of 35 mm

[0103] The preparation method of the heat-conducting adhesive comprises the following steps:

[0104] (1) Place 178 parts of ternary compounded heat-conducting powder in a 120°C vacuum drying oven for 24 h, and then naturally cool to 25°C for standby use.

[0105] (2) Put 2 parts of monofunctional trimethoxysilane-terminated polydimethylsilane and 20 parts of silicone oil into a planetary mixer and stir at a speed of 800 rpm for 5 min. Then add 178 parts of ternary compounded heat-conducting powder into the planetary mixer and stir at a speed of 1500 rpm for 15 min. Then, add 0.4 parts of catalyst and mix at a speed of 1000 rpm for 5 min. Finally, cure the material by stepwise temperature increase, and the specific curing procedure is: first cure at 100°C for 30 min, then cure at 120°C for 60 min, and finally cure at 150°C for 120 min.

[0106] Comparative Example 2

[0107] In this comparative example, a heat-conducting adhesive is provided, which comprises the following components in parts by weight:

[0108] 19 parts of silicone oil, 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane, 1 part of hyperbranched polyborosiloxane, 0.4 parts of catalyst, 178 parts of ternary compounded heat-conducting powder.

[0109] The silicone oil is amino silicone oil with a viscosity of 55 mm 2 / s (25°C) and epoxy silicone oil with a viscosity of 35 mm 2 / s (25°C) at a mass ratio of 1:1.1; the ternary compounded heat-conducting powder is composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical aluminum oxide with an average particle size of 0.5 μm at a mass ratio of 6:3:1.

[0110] The preparation method of the heat-conducting adhesive comprises the following steps:

[0111] (1) 178 parts of ternary compounded heat-conducting powder are placed in a 120°C vacuum drying oven for 24 h, and then naturally cooled to 25°C for standby use.

[0112] (2) 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane and 19 parts of silicone oil are added to a planetary mixer and stirred at a speed of 800 rpm for 5 min. Then 1 part of hyperbranched polyborosiloxane and 178 parts of ternary compounded heat-conducting powder are added to the planetary mixer and stirred at a speed of 1500 rpm for 15 min. Then, 0.4 parts of catalyst is added and mixed at a speed of 1000 rpm for 5 min. Finally, the material is cured by stepwise temperature rising, and the specific curing procedure is: first cured at 100°C for 30 min, then cured at 120°C for 60 min, and finally cured at 150°C for 120 min.

[0113] Comparative Example 3

[0114] In this comparative example, a heat-conducting adhesive is provided, which comprises the following components in terms of weight fraction:

[0115] 14 parts of silicone oil, 2 parts of monoterminally trimethoxysilane-terminated polydimethylsilane, 6 parts of hyperbranched polyborosiloxane, 0.4 parts of catalyst, 178 parts of ternary compounded heat-conducting powder.

[0116] The silicone oil is amino silicone oil with a viscosity of 55 mm 2 / s (25°C) and epoxy silicone oil with a viscosity of 35 mm 2 / s (25°C) at a mass ratio of 1:2.5; the ternary compounded heat-conducting powder is composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical aluminum oxide with an average particle size of 0.5 μm at a mass ratio of 6:3:1.

[0117] The preparation method of the heat-conducting adhesive comprises the following steps:

[0118] (1) 178 parts of the ternary compounded heat-conducting powder were placed in a vacuum drying oven at 120°C for 24 hours, and then naturally cooled to 25°C for standby.

[0119] (2) 2 parts of a single-end trimethoxysilane-terminated polydimethylsilane and 14 parts of a silicone oil were added to a planetary mixer and stirred at a speed of 800 rpm for 5 minutes. Then, 6 parts of a hyperbranched polyborosiloxane and 178 parts of the ternary compounded heat-conducting powder were added to the planetary mixer and stirred at a speed of 1500 rpm for 15 minutes. Then, 0.4 parts of a catalyst was added and mixed at a speed of 1000 rpm for 5 minutes. Finally, the material was cured by stepwise temperature rising, and the specific curing procedure was as follows: first cured at 100°C for 30 minutes, then cured at 120°C for 60 minutes, and finally cured at 150°C for 120 minutes.

[0120] The heat-conducting adhesive provided by the embodiment and the comparative example was subjected to performance testing, and the testing method was as follows:

[0121] (1) Adhesion strength test:

[0122] Referring to ASTM D1002, the interfacial thermal resistance of the sample was tested by single lap tensile shear, the testing temperature was 25°C, and the tensile rate was 10 mm / min.

[0123] (2) Thermal conductivity test:

[0124] Referring to ISO 22007-2, the thermal conductivity of the sample was tested by a transient method, and the testing temperature was 25°C.

[0125] (3) Viscosity test:

[0126] The viscosity of the sample was tested by a rheometer. The sample was placed under parallel plates with a diameter of 25 mm, and the test was performed by a rotation mode, and the shear rate was changed from 0 to 10 s -1 .

[0127] The performance test results are shown in Table 1.

[0128] Table 1

[0129]

[0130]

[0131] As can be seen from Table 1, the heat-conducting adhesive provided by the embodiment has high adhesion strength (3.14-5.13 MPa) and high thermal conductivity (4.01-6.58 W·m -1·K -1 ) and low viscosity (154-336 Pa-s).

[0132] Compared with Example 1, the adhesive strength of the thermal conductive adhesive provided by Comparative Example 1 is significantly decreased, the adhesive strength of the thermal conductive adhesive provided by Comparative Example 2 is significantly decreased, and the viscosity of the thermal conductive adhesive provided by Comparative Example 3 is significantly increased.

[0133] The applicant declares that the thermal conductive adhesive, the preparation method and the application thereof of the present application are illustrated by the above examples, but the present application is not limited to the above examples, i.e. it does not mean that the present application must rely on the above examples to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A thermally conductive adhesive, characterized in that, The thermally conductive adhesive comprises, by weight, the following components: 12-20 parts silicone oil, 2-5 parts hyperbranched polyborosiloxane, 1-3 parts powder treatment agent, 0.32-0.4 parts catalyst, and 178-182 parts thermally conductive powder.

2. The thermally conductive adhesive according to claim 1, characterized in that, The hyperbranched polyborosiloxane was prepared by the following method: 4-Bromophenylboronic acid, 3-aminopropyltriethoxysilane, organic solvent and water were mixed and stirred, then a catalyst was added, the reaction was carried out, and post-treatment was performed to obtain the hyperbranched polyborosiloxane.

3. The thermally conductive adhesive according to claim 2, characterized in that, The molar ratio of 4-bromophenylboronic acid and 3-aminopropyltriethoxysilane is 1:(0.8-1.2); Preferably, the organic solvent includes ethanol; Preferably, the volume ratio of the organic solvent to water is (5-8):1; Preferably, the mass ratio of 3-aminopropyltriethoxysilane to water is (10-12):1; Preferably, the stirring speed is 600-1000 rpm and the stirring time is 10-20 min; Preferably, the stirring is carried out under inert gas protection; Preferably, the inert gas includes nitrogen; Preferably, the catalyst comprises triethylamine; Preferably, the reaction temperature is 50–70°C and the reaction time is 20–30 h; Preferably, the post-processing includes vacuum rotary evaporation.

4. The thermally conductive adhesive according to any one of claims 1-3, characterized in that, The silicone oil includes any one or a combination of at least two of vinyl silicone oil, amino silicone oil, epoxy silicone oil, methylphenyl silicone oil, and hydroxyl silicone oil, preferably amino silicone oil and / or epoxy silicone oil; Preferably, the silicone oil comprises a mixture of amino silicone oil and epoxy silicone oil in a mass ratio of 1:(1-2); Preferably, the viscosity of the amino silicone oil at 25°C is 50–60 mm. 2 / s; Preferably, the epoxy silicone oil has a viscosity of 30-40 mm at 25°C. 2 / s.

5. The thermally conductive adhesive according to any one of claims 1-4, characterized in that, The powder treatment agent includes any one or a combination of at least two of amino silane coupling agents, sulfur-containing silane coupling agents, epoxy silane coupling agents, vinyl silane coupling agents, and alkane silane coupling agents, preferably alkane silane coupling agents. Preferably, the alkane-based silane coupling agent comprises a polydimethylsilane with a single-terminal trimethoxysilane end cap.

6. The thermally conductive adhesive according to any one of claims 1-5, characterized in that, The catalyst comprises 2-ethyl-4-methylimidazole.

7. The thermally conductive adhesive according to any one of claims 1-6, characterized in that, The thermally conductive powder includes any one or a combination of at least two of aluminum powder, silver powder, aluminum oxide, aluminum nitride, magnesium oxide, zinc oxide, and boron nitride, preferably aluminum powder and / or aluminum oxide; Preferably, the alumina comprises spherical alumina with an average particle size of 0.2 to 0.8 μm; Preferably, the aluminum powder comprises spherical aluminum powder with an average particle size of 1 to 30 μm, and more preferably spherical aluminum powder with an average particle size of 3 to 25 μm; Preferably, the thermally conductive powder comprises one or at least two of the following powders: A single-particle-size thermally conductive powder composed of spherical aluminum powder with an average particle size of 20.5 μm; A binary composite thermally conductive powder composed of spherical aluminum powder with an average particle size of 20.5 μm and spherical aluminum powder with an average particle size of 5.4 μm, with a mass ratio of (1~3):1; The ternary composite thermally conductive powder is composed of spherical aluminum powder with an average particle size of 20.5 μm, spherical aluminum powder with an average particle size of 5.4 μm, and spherical alumina with an average particle size of 0.5 μm, with a mass ratio of (5~7):(2~4):

1.

8. A method for preparing a thermally conductive adhesive as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: The silicone oil and powder treatment agent are mixed for the first time, then hyperbranched polyborosiloxane and thermally conductive powder are added for the second mixing, followed by the addition of a catalyst for the third mixing, and then cured to obtain the thermally conductive adhesive.

9. The preparation method according to claim 8, characterized in that, The thermally conductive powder is dried before use; Preferably, the drying temperature is 110–130°C, and the drying time is 20–30 hours. Preferably, the rotation speed of the first mixing is 700-900 rpm, and the mixing time is 4-6 min; Preferably, the rotation speed of the second mixing is 1400-1600 rpm, and the mixing time is 10-20 min; Preferably, the rotation speed of the third mixing is 800-1200 rpm, and the mixing time is 3-8 min; Preferably, the curing is performed by stepwise temperature increase, including: first curing at 80-120℃ for 20-40 min, then curing at 110-130℃ for 50-70 min, and then curing at 140-160℃ for 110-130 min.

10. The application of a thermally conductive adhesive as described in any one of claims 1-7 in electronic devices.

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