A kind of thermal conductive silicone rubber and preparation method thereof

Abstract

The present invention relates to the technical field of thermally conductive silicone rubber, and in particular to a thermally conductive silicone rubber and a preparation method thereof. The present invention proposes a thermally conductive silicone rubber and a preparation method thereof. A thermally conductive silicone rubber, the raw materials of the silicone rubber include: vinyl-terminated polydimethylsiloxane, vinyl MQ resin, hydrogen-containing silicone oil, ethynyl cyclohexanol, and modified silver powder; the modified silver powder is a mixture containing silicone resin and silver powder. In the thermally conductive silicone rubber provided by the present invention, by using silicone resin-coated silver powder, the thermally conductive silicone rubber of the present invention has suitable fluidity and high thermal conductivity before curing, which can meet the market demand for the use of ultra-high thermal conductivity silicone rubber. The thermally conductive silicone rubber provided by the present invention can be applied to structural heat dissipation components such as ultra-high power light-emitting chips.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal conductive silicone rubber, and in particular to a thermal conductive silicone rubber and a preparation method thereof. Background Art

[0002] In existing technology, thermally conductive silicone rubber is generally based on polysiloxane and filled with mixed metal oxides. The thermal conductivity of thermally conductive silicone rubber is generally between 0.5 and 8 W / (m·K). To meet market demand and obtain silicone rubber with higher thermal conductivity, current research generally requires filling silicone rubber with metal powders such as copper, silver, and nickel. However, due to the inherent properties of metal powders, the fluidity of thermally conductive silicone rubber after adding metal powders does not meet the required application requirements before curing, limiting its application value.

[0003] Therefore, how to prepare a silicone rubber that has fluidity and high thermal conductivity before curing is the key to current research. Summary of the Invention

[0004] In order to solve the above problems in the prior art, the present invention provides a thermally conductive silicone rubber and a preparation method thereof.

[0005] In a first aspect, the present invention provides a thermally conductive silicone rubber, wherein the raw materials of the silicone rubber include: vinyl-terminated polydimethylsiloxane, vinyl MQ resin, hydrogen-containing silicone oil, ethynyl cyclohexanol, and modified silver powder; the modified silver powder is a mixture containing silicone resin and silver powder.

[0006] Specifically, the CAS number of the vinyl MQ resin in the present invention is CAS: 68988-89-6.

[0007] Specifically, the modified silver powder is silver powder coated with silicone resin. The coating in the present invention includes partial adhesion, partial covering, partial wrapping, full wrapping and the like.

[0008] As a specific embodiment of the present invention, when the shear rate is 0.2S -1 When the viscosity of the thermally conductive silicone rubber of the present invention is 60000-100000 mPa·s;

[0009] As a specific embodiment of the present invention, the thermal conductivity of the thermally conductive silicone rubber in the present invention is 10 to 18 W / (m·K);

[0010] As a specific embodiment of the present invention, the hardness of the thermally conductive silicone rubber after curing is 50-95A.

[0011] As a specific embodiment of the present invention, the raw materials of the silicone rubber include, by weight: 60 to 80 parts of vinyl-terminated polydimethylsiloxane, 20 to 40 parts of vinyl MQ resin, 3 to 5 parts of hydrogenated silicone oil, 0.008 to 0.012 parts of ethynyl cyclohexanol, and 350 to 700 parts of modified silver powder.

[0012] As a specific embodiment of the present invention, the mass content of hydrogen in the hydrogen-containing silicone oil is 1.1% to 1.3%.

[0013] As a specific embodiment of the present invention, the raw materials of the modified silver powder include, by weight: 4 to 6 parts of silicone resin, 180 to 220 parts of solvent, and 80 to 120 parts of silver powder;

[0014] Further preferably, the solvent is toluene;

[0015] As a specific embodiment of the present invention, the d50 value of the silver powder is 1 to 5 μm.

[0016] As a specific embodiment of the present invention, the softening point of the silicone resin is 60-70°C.

[0017] As a specific embodiment of the present invention, the raw materials of the silicone resin include: octamethylcyclotetrasiloxane, diphenyldimethoxysilane, phenyltrimethoxysilane, toluene, concentrated sulfuric acid, and water.

[0018] As a specific embodiment of the present invention, the raw materials of the silicone resin include, by mass, 120 to 140 parts of octamethylcyclotetrasiloxane, 420 to 460 parts of diphenyldimethoxysilane, 800 to 1200 parts of phenyltrimethoxysilane, 600 to 1000 parts of toluene, 24 to 34 parts of concentrated sulfuric acid, and 420 to 600 parts of water.

[0019] More preferably, the water is deionized water or distilled water.

[0020] As a specific embodiment of the present invention, the concentration of concentrated sulfuric acid is 97 wt % to 99 wt %.

[0021] As a specific embodiment of the present invention, the preparation method of the modified silver powder includes: drying and grinding a mixture containing silicone resin, solvent and silver powder to obtain the modified silver powder.

[0022] Preferably, the grinding time is 8 to 10 hours. Specifically, the grinding is performed using a ball mill.

[0023] As a specific embodiment of the present invention, a method for preparing a silicone resin includes: mixing and stirring octamethylcyclotetrasiloxane, diphenyldimethoxysilane, phenyltrimethoxysilane, toluene, concentrated sulfuric acid, and water to obtain a mixed solution, allowing the mixed solution to stand, separating the mixed solution into an oil layer and a water layer, separating the water layer, adjusting the pH value of the oil layer, filtering, drying, and crushing to obtain the silicone resin;

[0024] Preferably, the stirring is reflux stirring, and the conditions for reflux stirring include: temperature of 70-80° C. and time of 5-7 h.

[0025] As a specific embodiment of the present invention, the pH value of the oil layer is adjusted to 6.5-7.5.

[0026] In a second aspect, the present invention provides a method for preparing thermally conductive silicone rubber, comprising: mixing vinyl-terminated polydimethylsiloxane, vinyl MQ resin, hydrogenated silicone oil, ethynyl cyclohexanol and modified silver powder in the presence of a catalyst to obtain thermally conductive silicone rubber.

[0027] As a specific embodiment of the present invention, the catalyst is a platinum complex, and the amount of the catalyst is such that the mass of platinum is 15 to 40 ppm of the total mass of the raw materials in the thermal conductive silicone rubber excluding the modified silver powder.

[0028] Specifically, the platinum complex is a polyvinylsiloxane platinum complex.

[0029] Specifically, the platinum complex catalyst is a Custer platinum catalyst.

[0030] As a specific embodiment of the present invention, the mixing time for preparing the thermally conductive silicone rubber is 0.2 to 0.5 h.

[0031] Specifically, vinyl-terminated polydimethylsiloxane, vinyl MQ resin, hydrogenated silicone oil, ethynyl cyclohexanol and modified silver powder are mixed using a three-roll mill or a centrifuge to obtain a mixture, and the mixture is mixed in the three-roll mill or the centrifuge for 0.2 to 0.5 hours.

[0032] Compared with the prior art, the present invention has the following beneficial effects.

[0033] The raw materials of the thermal conductive silicone rubber provided by the present invention are provided with appropriate fluidity (when the shear rate is 0.2S -1 The viscosity of the thermally conductive silicone rubber of the present invention is 60,000 to 100,000 mPa·s and the thermal conductivity is relatively high. Based on this, the thermally conductive silicone rubber provided by the present invention can meet the market demand for ultra-high thermal conductivity silicone rubber.

[0034] The thermally conductive silicone rubber provided by the present invention can be applied to structural heat dissipation components such as ultra-high power light-emitting chips. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to specific examples, but they do not constitute any limitation to the present invention.

[0036] The raw materials used in the embodiments of the present invention are all commercially available.

[0037] Among them, octamethylcyclotetrasiloxane was purchased from Hesheng Silicon Industry Co., Ltd.

[0038] Diphenyldimethoxysilane was purchased from Liaoning Xinbang New Materials Co., Ltd.

[0039] Phenyltrimethoxysilane was purchased from Liaoning Xinbang New Materials Co., Ltd.

[0040] Toluene was purchased from Beijing Yili Fine Chemicals Co., Ltd.

[0041] Concentrated sulfuric acid, 98 wt% purchased from Beijing Yili Fine Chemicals Co., Ltd.

[0042] Silver powder, particle size, d50 of 2 μm was purchased from Jiangsu Boqian New Materials Co., Ltd.

[0043] Vinyl-terminated polydimethylsiloxane was purchased from Shanghai Huazhirun Chemical Co., Ltd.

[0044] Vinyl MQ resin was purchased from Chengdu Boda Aifu Technology Co., Ltd. Model 8201-3

[0045] Hydrogenated silicone oil was purchased from Jiangxi Haiduo Silicone Materials Co., Ltd.

[0046] Ethylene cyclohexanol was purchased from J&K Technology Co., Ltd. CAS: 78-27-3

[0047] The platinum complex catalyst was purchased from Shanghai Vivo Chemical Co., Ltd. CAS No. 68478-92-2. Before use, the platinum complex catalyst was diluted with vinyl-terminated polydimethylsiloxane to a platinum concentration of 1 wt %.

[0048] Synthesis of silicone resin

[0049] 130 g of octamethylcyclotetrasiloxane, 440 g of diphenyldimethoxysilane, 1000 g of phenyltrimethoxysilane, 800 g of toluene, 29 g of concentrated sulfuric acid, and 510 g of deionized water were mixed and stirred at reflux at 70° C. for 6 h to obtain a mixed solution. The mixed solution was allowed to stand and cooled to room temperature. The mixed solution separated into an oil layer and an aqueous layer, and the aqueous layer was separated. Sodium bicarbonate was added to the oil layer to adjust the pH of the oil layer to 7, stirred at room temperature for 1 h, and filtered to obtain a mixture. The mixture was dried and crushed to form a silicone resin.

[0050] The test method for the softening point of silicone resin is:

[0051] Instrument: PerkinElmer Differential Scanning Calorimeter Model: DSC6000

[0052] Test method: Heating from -85℃ to 150℃, heating rate 10℃ / min

[0053] The softening point of silicone resin was measured by DSC and was 65.2℃.

[0054] Synthesis of modified silver powder

[0055] 50 g of the silicone resin prepared above was weighed and mixed with 2000 g of toluene, stirred and dissolved, 1000 g of silver powder with a d50 value of 2 μm was added, and stirred at room temperature for 8 h to obtain a mixture. The mixture was dried and ball milled for 8 h to obtain modified silver powder.

[0056] In a specific embodiment of the present invention, the above steps of synthesizing the silicone resin and the modified silver powder are repeated to obtain sufficient silicone resin and modified silver powder for use in the examples and comparative examples.

[0057] Example 1

[0058] Weigh 70 g of vinyl-terminated polydimethylsiloxane, 30 g of vinyl MQ resin, 4.3 g of hydrogenated silicone oil with a hydrogen content of 1.2 wt%, 0.01 g of ethynyl cyclohexanol, 0.3 g of diluted platinum complex catalyst, and 350 g of modified silver powder, and mix them in a three-roll mill for 0.5 h to obtain a thermally conductive silicone rubber.

[0059] Example 2

[0060] Weigh 60 g of vinyl-terminated polydimethylsiloxane, 40 g of vinyl MQ resin, 4.8 g of hydrogenated silicone oil with a hydrogen content of 1.1 wt%, 0.01 g of ethynyl cyclohexanol, 0.3 g of diluted platinum complex catalyst, and 400 g of modified silver powder, and mix them in a three-roll mill for 0.5 h to obtain a thermally conductive silicone rubber.

[0061] Example 3

[0062] Weigh 80 g of vinyl-terminated polydimethylsiloxane, 20 g of vinyl MQ resin, 3.9 g of hydrogenated silicone oil with a hydrogen content of 1.3 wt%, 0.01 g of ethynyl cyclohexanol, 0.3 g of diluted platinum complex catalyst, and 650 g of modified silver powder, and mix them in a three-roll mill for 0.5 h to obtain a thermally conductive silicone rubber.

[0063] Example 4

[0064] Weigh 60 g of vinyl-terminated polydimethylsiloxane, 40 g of vinyl MQ resin, 4.5 g of hydrogenated silicone oil with a hydrogen content of 1.2 wt%, 0.01 g of ethynyl cyclohexanol, 0.3 g of diluted platinum complex catalyst, and 700 g of modified silver powder, and mix them in a three-roll mill for 0.5 h to obtain a thermally conductive silicone rubber.

[0065] Comparative Example 1

[0066] Comparative Example 1 was prepared based on Example 1. The difference between Comparative Example 1 and Example 1 is that silver powder with a d50 value of 2 μm was directly used in the preparation process of the thermally conductive silicone rubber, that is, the silver powder was not modified.

[0067] Comparative Example 2

[0068] Comparative Example 2 is set on the basis of Example 1. The difference between Comparative Example 2 and Example 1 is that the synthesis process of the modified silver powder is as follows:

[0069] Stir and dissolve 50g of silicone resin and 2000g of toluene. Add 1000g of silver powder with a d50 value of 2μm. Stir at room temperature for 8 hours, dry, and grind to obtain modified silver powder. The silicone resin should have a softening point of 51.6°C.

[0070] A silicone resin with a softening point of 51.6°C is synthesized by mixing 130g of octamethylcyclotetrasiloxane, 440g of diphenyldimethoxysilane, 500g of phenyltrimethoxysilane, 800g of toluene, 29g of concentrated sulfuric acid, and 510g of deionized water. The mixture is stirred at reflux at 70°C for 6 hours to obtain a mixed solution. The mixture is allowed to stand and cool to room temperature. The mixture separates into an oil layer and an aqueous layer, which is then separated. Sodium bicarbonate is added to the oil layer to adjust the pH to 7. The mixture is stirred at room temperature for 1 hour, filtered, and dried and crushed to form a silicone resin. The softening point of the silicone resin is tested to be 51.6°C.

[0071] Comparative Example 3

[0072] Comparative Example 3 is set on the basis of Example 1. The difference between Comparative Example 3 and Example 1 is that the synthesis process of the modified silver powder is as follows:

[0073] Stir and dissolve 50g of silicone resin and 2000g of toluene. Add 1000g of silver powder with a d50 value of 2μm. Stir at room temperature for 8 hours, dry, and grind to obtain modified silver powder. The silicone resin should have a softening point of 78.9°C.

[0074] A silicone resin with a softening point of 78.9°C is synthesized by mixing 130g of octamethylcyclotetrasiloxane, 440g of diphenyldimethoxysilane, 1500g of phenyltrimethoxysilane, 800g of toluene, 29g of concentrated sulfuric acid, and 510g of deionized water. The mixture is stirred at reflux at 70°C for 6 hours to obtain a mixed solution. The mixture is allowed to stand and cool to room temperature. The mixture separates into an oil layer and an aqueous layer, which is then separated. Sodium bicarbonate is added to the oil layer to adjust the pH of the oil layer to 7. The mixture is stirred at room temperature for 1 hour, filtered, and dried and crushed to form a silicone resin. The softening point of the silicone resin is tested to be 78.9°C.

[0075] Comparative Example 4

[0076] Comparative Example 4 is set on the basis of Example 1. The difference between Comparative Example 4 and Example 1 is that the preparation process of the modified silver powder is as follows:

[0077] Weigh 50 g of the silicone resin with a softening point of 65.2°C prepared above and 2000 g of toluene, stir and dissolve, add 1000 g of silver powder with a d50 value of 8 μm, stir at room temperature for 8 h, dry, and grind to obtain modified silver powder.

[0078] Comparative Example 5

[0079] Comparative Example 1 is set up on the basis of Example 1. The difference between Comparative Example 5 and Example 1 is that the preparation process of the modified silver powder is:

[0080] 30 g of the silicone resin with a softening point of 65.2°C prepared above and 2000 g of toluene were weighed and dissolved by stirring. 1200 g of silver powder with a d50 value of 2 μm was added and stirred at room temperature for 8 h. The mixture was dried and ground to obtain modified silver powder.

[0081] Comparative Example 6

[0082] Comparative Example 1 is set on the basis of Example 1. The difference between Comparative Example 6 and Example 1 is that the preparation process of the modified silver powder is:

[0083] 70 g of the silicone resin with a softening point of 65.2° C. prepared above and 2000 g of toluene were weighed and dissolved by stirring. 800 g of silver powder with a d50 value of 2 μm was added and stirred at room temperature for 8 h. The mixture was dried and ground to obtain modified silver powder.

[0084] The performance of the thermally conductive silicone rubbers prepared in Examples 1 to 4 and Comparative Examples 1 to 6 was tested.

[0085] Thermal conductive silicone rubber viscosity test

[0086] Instrument: Anton Paar rheometer

[0087] Model: MCR102

[0088] Test conditions: 0.2S -1 , 10 minutes

[0089] Thermal conductivity test of thermal conductive silicone rubber

[0090] Instrument: Hot Disk thermal constant analyzer

[0091] Test principle: transient plane heat source method

[0092] Sample preparation requirements: 30*30*0.2mm test sample, 150℃*2h curing

[0093] Hardness test of thermal conductive silicone rubber after heat curing

[0094] Instrument: Shore A hardness tester

[0095] Sample preparation requirements: 20*10*20mm square block, 150℃*2h curing

[0096] Table 1 Test results of thermal conductive silicone rubber properties prepared in Examples 1 to 4 and Comparative Examples 1 to 6

[0097] Viscosity / mPa.s Thermal conductivity / W / (m·K) Hardness after heat curing / A Example 1 60580 10.03 50 Example 2 72860 13.66 67 Example 3 85700 15.21 80 Example 4 99860 17.88 95 Comparative Example 1 863000 2.33 53 Comparative Example 2 56920 7.67 48 Comparative Example 3 108500 6.33 49 Comparative Example 4 110600 3.56 57 Comparative Example 5 220530 7.22 52 Comparative Example 6 51450 3.13 49

[0098] Comparison of the examples and comparative examples shows that the thermally conductive silicone rubber prepared by the present invention has an appropriate viscosity, ensuring that the fluidity of the thermally conductive silicone rubber before curing meets the use requirements, while also having a relatively high thermal conductivity. The thermally conductive silicone rubber prepared by the present invention has a wide range of applications.

[0099] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A thermally conductive silicone rubber, characterized in that: The raw materials of the silicone rubber include, by weight: 60-80 parts of vinyl-terminated polydimethylsiloxane, 20-40 parts of vinyl MQ resin, 3-5 parts of hydrogenated silicone oil, 0.008-0.012 parts of ethynyl cyclohexanol, and 350-700 parts of modified silver powder; The raw materials of the modified silver powder include, by weight, 4 to 6 parts of silicone resin, 180 to 220 parts of solvent, and 80 to 120 parts of silver powder; the d50 value of the silver powder is 1 to 5 μm, and the softening point of the silicone resin is 60 to 70° C. The raw materials of the silicone resin include, by weight: 120-140 parts of octamethylcyclotetrasiloxane, 420-460 parts of diphenyldimethoxysilane, 800-1200 parts of phenyltrimethoxysilane, 600-1000 parts of toluene, 24-34 parts of concentrated sulfuric acid, and 420-600 parts of water; The preparation method of the silicone resin comprises: mixing and stirring octamethylcyclotetrasiloxane, diphenyldimethoxysilane, phenyltrimethoxysilane, toluene, concentrated sulfuric acid and water to obtain a mixed liquid, allowing the mixed liquid to stand, separating the mixed liquid into an oil layer and a water layer, separating the water layer, adjusting the pH value of the oil layer, filtering, drying and crushing to obtain the silicone resin.

2. The thermally conductive silicone rubber according to claim 1, characterized in that: The thermal conductivity of the thermally conductive silicone rubber is 10~18W / (m·K); the hardness of the thermally conductive silicone rubber after curing is 50~95A; when the shear rate is 0.2S -1 When the thermally conductive silicone rubber has a viscosity of 60,000 to 100,000 mPa·s.

3. The thermally conductive silicone rubber according to claim 1 or 2, characterized in that: The mass content of hydrogen in the hydrogen-containing silicone oil is 1.1% to 1.3%.

4. The thermally conductive silicone rubber according to claim 1 or 2, characterized in that: The solvent is toluene.

5. The thermally conductive silicone rubber according to claim 1 or 2, characterized in that: The water is deionized water or distilled water; And / or, the concentration of the concentrated sulfuric acid is 97wt%~99wt%.

6. The thermally conductive silicone rubber according to claim 1 or 2, characterized in that: The preparation method of the modified silver powder comprises: drying and grinding a mixture containing silicone resin, solvent and silver powder to obtain the modified silver powder.

7. The thermally conductive silicone rubber according to claim 6, characterized in that: The grinding time is 8~10h.

8. The thermally conductive silicone rubber according to claim 1 or 2, characterized in that: The stirring is reflux stirring, and the conditions of the reflux stirring include: temperature of 70-80° C., time of 5-7 h; and / or, adjusting the pH value of the oil layer to 6.5-7.

5.

9. A method for preparing the thermally conductive silicone rubber according to any one of claims 1 to 8, characterized in that: The preparation method comprises: in the presence of a catalyst, mixing vinyl-terminated polydimethylsiloxane, vinyl MQ resin, hydrogenated silicone oil, ethynyl cyclohexanol and modified silver powder to obtain the thermally conductive silicone rubber.

10. The method for preparing thermally conductive silicone rubber according to claim 9, wherein: The catalyst is a platinum complex, and the amount of the catalyst is such that the mass of the platinum is 15 to 40 ppm of the total mass of the raw materials in the thermal conductive silicone rubber excluding the modified silver powder; And / or, the mixing time is 0.2~0.5h.