Heat-conducting silicone grease capable of being ceramized at high temperature and preparation method of heat-conducting silicone grease

Abstract

The invention belongs to the technical field of heat-conducting silicone grease, and particularly discloses heat-conducting silicone grease capable of being vitrified at high temperature and a preparation method of the heat-conducting silicone grease, and the heat-conducting silicone grease is prepared from the following raw material components: 10-30 parts of boron-containing modified methyl silicone oil, 50-150 parts of a heat-conducting filler capable of being vitrified and 0.05-0.20 part of octyl silane. According to the invention, the boron-containing modified methyl silicone oil is used as a basic polymer, and can accelerate the ceramization process of the silicone grease under a high-temperature condition. Octylsilane serves as a filler treating agent, and wettability of filler and silicone oil is improved. The heat-conducting silicone grease capable of being vitrified at high temperature prepared by the invention can perfectly solve the problems of pulverization and cracking; at room temperature, the silicone grease is kept in a paste state, is convenient for construction, and can be effectively coated in gaps among various components; under the condition of high-temperature working, the silicone grease is converted into a thin and compact ceramic layer from a paste state, and is tightly attached between the components.

Description

Technical Field

[0001] The invention relates to the technical field of thermal conductive silicone grease, and in particular to a thermal conductive silicone grease capable of being ceramicized at high temperature and a preparation method thereof. Background Art

[0002] With the rapid development of electronic technology, electronic components are gradually tending towards high power consumption, miniaturization, and integration. How to dissipate the heat inside and on the surface of the device in a timely manner has become the focus of current device design and the key to ensuring reliability. Due to design and layout issues, there will inevitably be gaps between components in various electronic devices. The thermal conductivity of air is only 0.0242W / (m·K), which is a poor conductor of heat. When electronic components work for a long time, the heat generated inside will continue to accumulate. Relying solely on the heat sink to dissipate the heat cannot conduct the heat away in a short time.

[0003] Thermal grease is one of the commonly used thermal interface materials. It is a heat dissipation material that maintains a paste state for a long time at room temperature. It has high thermal conductivity, is easy to construct, and has good wettability to the interface. It is used to fill the gap between the heating element and the radiator. It can effectively reduce the thermal resistance of the interface and improve the heat dissipation efficiency of the components. Traditional thermal grease is usually based on methyl silicone oil as a polymer. Most of the thermal conductive fillers are inorganic particles such as aluminum powder, aluminum oxide, zinc oxide, aluminum nitride, and boron nitride as thermal conductive fillers. It is made through a specific mixing process. The thermal grease prepared by this preparation method is prone to oil-powder separation when working under high temperature conditions for a long time, causing the grease to crack and powderize, affecting the final heat dissipation effect of the components. Summary of the invention

[0004] In view of the above-mentioned shortcomings, the present invention provides a thermally conductive silicone grease that can be ceramicized at high temperature and a preparation method thereof. The present invention uses boron-modified methyl silicone oil as a base polymer and one or more of ceramicized aluminum oxide, zinc oxide, aluminum powder, and copper powder as thermally conductive fillers. The boron-modified methyl silicone oil can accelerate the ceramicization process of the silicone grease under high temperature conditions. Octylsilane is used as a filler treatment agent to increase the wettability of the filler and silicone oil. The thermally conductive silicone grease that can be ceramicized at high temperature prepared by the present invention can perfectly solve the problems of powdering and cracking; under room temperature conditions, the silicone grease remains in a paste state, which is easy to construct and can be effectively coated in the gaps between various components; under high temperature (above 120°C) working conditions, the silicone grease is transformed from a paste state into a thin layer of dense ceramic layer, which fits tightly between components.

[0005] In order to achieve the above object, the present invention provides a high temperature ceramic thermal conductive silicone grease, which is composed of the following raw material components in terms of mass fraction:

[0006] 10-30 parts of boron-modified methyl silicone oil;

[0007] 50-150 parts of ceramic thermal conductive filler;

[0008] Octylsilane 0.05-0.20 parts.

[0009] According to one aspect of the present invention, the preparation method of the boron-modified methyl silicone oil is:

[0010] Boric acid and polyol are subjected to esterification reaction to generate boric ester, the boric ester and hydrogen-containing silicone oil are added to a reaction kettle and mixed evenly, and then a platinum catalyst is added, the temperature is raised to 80-150° C., the reaction is performed for 1.5-3.5 hours, and then the boron-modified methyl silicone oil is obtained through washing and distillation.

[0011] In a specific embodiment, the molar ratio of boric acid to hydroxyl groups in the polyol is 1:1.

[0012] It should be noted that the above-mentioned washing is performed with deionized water, the purpose of which is to remove excess salts; the purpose of the above-mentioned distillation is to remove water.

[0013] According to one aspect of the present invention, the structural formula of the boric acid is: B(OH)3R; wherein R is any one selected from methyl, ethyl, and propyl.

[0014] In a specific embodiment, in the boronic acid B(OH)3R, R is a methyl group.

[0015] According to one aspect of the present invention, the hydrogen content of the hydrogen-containing silicone oil is 0.1-0.5 wt % and the viscosity is 50-300 cp.

[0016] It should be noted that the methyl group in the boron-modified methyl silicone oil comes from hydrogen-containing silicone oil, wherein the structural formula of the hydrogen-containing silicone oil is shown in the following formula I:

[0017]

[0018] According to one aspect of the present invention, the mass ratio of the borate ester to the hydrogen-containing silicone oil is 0.5-1.5:5-8.

[0019] According to one aspect of the present invention, the platinum catalyst is chloroplatinic acid; based on 100 parts of the total number of components of the reaction system containing boron-modified methyl silicone oil, the chloroplatinic acid is 0.05-0.15 parts.

[0020] According to one aspect of the present invention, the ceramicized thermally conductive filler is one or more of ceramicized aluminum oxide, ceramicized zinc oxide, ceramicized aluminum powder, and ceramicized copper powder; and the particle size of the ceramicized thermally conductive filler is 5-20 um.

[0021] In a specific embodiment, the ceramicizable alumina includes at least one of α-Al2O3, γ-Al2O3, and nano-alumina.

[0022] In a specific embodiment, the ceramicizable zinc oxide includes at least one of ceramic-grade zinc oxide, calcined zinc oxide, and indirect-process zinc oxide.

[0023] In a specific embodiment, the ceramicizable copper powder includes at least one of nano copper powder, flaky copper powder, and spherical copper powder.

[0024] According to one aspect of the present invention, the octylsilane is n-octyltriethoxysilane.

[0025] In a specific embodiment, the octylsilane is n-octyltriethoxysilane, and the molecular formula is 276.49.

[0026] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned high temperature ceramic thermal conductive silicone grease, comprising the following steps:

[0027] S1. Add boron-modified methyl silicone oil and 1 / 2 of octylsilane into a mixer and stir evenly;

[0028] S2, adding the ceramic thermal conductive filler into the above mixer three times and stirring;

[0029] S3, adding 1 / 2 of octylsilane into the above mixer and stirring, then discharging the material, and after vacuum degassing, obtaining a high temperature ceramic thermal conductive silicone grease.

[0030] Beneficial effects of the present invention:

[0031] (1) The present invention forms a new Si-B bond by reacting the BO bond of the borate ester with the silicon-hydrogen bond in the hydrogen-containing silicone oil under the catalytic action of chloroplatinic acid, so that the boron-modified methyl silicone oil inherits some basic properties of ordinary silicone oil. At the same time, due to the introduction of boron element, it exhibits better temperature resistance and thermal stability than ordinary silicone oil, and has relatively high reaction activity;

[0032] (2) Under the interaction of the boron-modified methyl silicone oil of the present application and the ceramicizable thermal conductive filler, the thermal conductive silicone grease can be quickly ceramicized under high temperature conditions. At the same time, due to its excellent temperature resistance and thermal stability, the silicone grease has a wider operating temperature range;

[0033] (3) The thermal conductive silicone grease of the present invention can be transformed into a dense ceramic layer under high temperature conditions, which fits the components tightly, thus avoiding the problems of oil-powder separation, powderization and cracking of traditional thermal conductive silicone grease under high temperature conditions;

[0034] (4) The preparation method of the present invention has a simple process and is easy to implement large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The state diagram of the silicone grease of the embodiment of the present invention before high temperature; wherein a is embodiment 1; b is embodiment 2; c is embodiment 3; d is embodiment 4;

[0036] Figure 2 The state diagram of the silicone grease of the comparative example of the present invention before high temperature; wherein a is comparative example 1; b is comparative example 2; c is comparative example 3;

[0037] Figure 3 The state diagram of the silicone grease of the embodiment of the present invention after high temperature; wherein a is embodiment 1; b is embodiment 2; c is embodiment 3; d is embodiment 4;

[0038] Figure 4 This is a state diagram of the silicone grease of the comparative example of the present invention after high temperature; wherein a is comparative example 1; b is comparative example 2; and c is comparative example 3. DETAILED DESCRIPTION

[0039] To make the present invention easier to understand, the present invention is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by professional and technical personnel in the field; unless otherwise specified, the raw materials and reagents involved in this article can be purchased from the market or prepared by known methods.

[0040] Example 1

[0041] A high temperature ceramic thermal conductive silicone grease and a preparation method thereof, comprising the following steps:

[0042] (1) First, boric acid and polyol are subjected to an esterification reaction at a molar ratio of 1:1 between boric acid and the hydroxyl group in the polyol to generate boric ester, and the prepared boric ester and hydrogen-containing silicone oil with a hydrogen content of 0.2% by mass and a viscosity of 50cp are added to a reactor at a mass ratio of 1:6 for uniform mixing, and then 0.1 parts of chloroplatinic acid are added as a catalyst, and the temperature is raised to 120°C for reaction for 2 hours, and the reacted material is washed with water to remove excess salts, and then distilled for 2 hours to remove water, and finally a boron-modified methyl silicone oil with a viscosity of 50cp is obtained. Wherein, in the boric acid B(OH)3R, R is a methyl group.

[0043] (2) Add 20 parts of boron-modified methyl silicone oil with a viscosity of 50 cp and 0.05 parts of octylsilane into a blender and stir evenly. The octylsilane is n-octyltriethoxysilane with a molecular formula of 276.49.

[0044] (3) 100 parts of ceramic alumina powder with a particle size of 5 μm was added to the mixer in step (2) three times in sequence, and stirred for 20 minutes each time.

[0045] (4) After the powder in step (3) is stirred, 0.05 parts of octylsilane is added thereto and stirring is continued for 20 minutes before discharging the material. After vacuum degassing is completed, the required thermal conductive silicone grease is obtained.

[0046] Example 2

[0047] A high temperature ceramic thermal conductive silicone grease and a preparation method thereof, comprising the following steps:

[0048] (1) First, boric acid and polyol are subjected to an esterification reaction at a molar ratio of 1:1 between boric acid and the hydroxyl group in the polyol to generate boric ester, and the prepared boric ester and hydrogen-containing silicone oil with a hydrogen content of 0.2% by mass and a viscosity of 100cp are added to a reactor at a mass ratio of 1:6 for uniform mixing, and then 0.1 parts of chloroplatinic acid are added as a catalyst, the temperature is raised to 120°C, and the reaction is performed for 2 hours, and the reacted material is washed with water to remove excess salts, and then distilled for 2 hours to remove water, and finally a boron-modified methyl silicone oil with a viscosity of 100cp is obtained. Wherein, in the boric acid B(OH)3R, R is a methyl group.

[0049] (2) 15 parts of boron-modified methyl silicone oil with a viscosity of 100 cp and 0.10 parts of octylsilane are added into a mixer and stirred evenly. The octylsilane is n-octyltriethoxysilane with a molecular formula of 276.49.

[0050] (3) 120 parts of ceramic zinc oxide powder with a particle size of 10 μm was added to the mixer in step (2) three times in sequence, and stirred for 20 minutes each time.

[0051] (4) After the powder in step (3) is stirred, 0.10 parts of octylsilane is added thereto and stirring is continued for 20 minutes before discharging the material. After vacuum degassing is completed, the required thermal conductive silicone grease is obtained.

[0052] Example 3

[0053] A high temperature ceramic thermal conductive silicone grease and a preparation method thereof, comprising the following steps:

[0054] (1) First, boric acid and polyol are subjected to an esterification reaction at a molar ratio of 1:1 between boric acid and the hydroxyl group in the polyol to generate boric ester, and the prepared boric ester and hydrogen-containing silicone oil with a hydrogen content of 0.2% by mass and a viscosity of 50cp are added to a reactor at a mass ratio of 1:6 for uniform mixing, and then 0.1 parts of chloroplatinic acid are added as a catalyst, and the temperature is raised to 120°C for reaction for 2 hours, and the reacted material is washed with water to remove excess salts, and then distilled for 2 hours to remove water, and finally a boron-modified methyl silicone oil with a viscosity of 50cp is obtained. Wherein, in the boric acid B(OH)3R, R is a methyl group.

[0055] (2) Add 25 parts of boron-modified methyl silicone oil with a viscosity of 50 cp and 0.10 parts of octylsilane into a mixer and stir evenly. The octylsilane is n-octyltriethoxysilane with a molecular formula of 276.49.

[0056] (3) 80 parts of a ceramic conductive filler prepared by mixing ceramic alumina powder (particle size of 5 μm) and ceramic zinc oxide powder (particle size of 20 μm) in a mass ratio of 1:1 was added to the mixer in step (2) three times in sequence, and stirred for 20 minutes each time.

[0057] (4) After the powder in step (3) is stirred, 0.10 parts of octylsilane is added thereto and stirring is continued for 20 minutes before discharging the material. After vacuum degassing is completed, the required thermal conductive silicone grease is obtained.

[0058] Example 4

[0059] A high temperature ceramic thermal conductive silicone grease and a preparation method thereof, comprising the following steps:

[0060] (1) First, boric acid and polyol are subjected to an esterification reaction at a molar ratio of 1:1 between boric acid and the hydroxyl group in the polyol to generate boric ester, and the prepared boric ester and hydrogen-containing silicone oil with a hydrogen content of 0.2% by mass and a viscosity of 50cp are added to a reactor at a mass ratio of 1:6 for uniform mixing, and then 0.1 parts of chloroplatinic acid are added as a catalyst, and the temperature is raised to 120°C for reaction for 2 hours, and the reacted material is washed with water to remove excess salts, and then distilled for 2 hours to remove water, and finally a boron-modified methyl silicone oil with a viscosity of 50cp is obtained. Wherein, in the boric acid B(OH)3R, R is a methyl group.

[0061] (2) Add 25 parts of boron-modified methyl silicone oil with a viscosity of 50 cp and 0.10 parts of octylsilane into a mixer and stir evenly. The octylsilane is n-octyltriethoxysilane with a molecular formula of 276.49.

[0062] (3) 100 parts of a ceramic conductive filler prepared by mixing ceramic alumina powder (particle size of 10 μm) and ceramic zinc oxide powder (particle size of 20 μm) in a mass ratio of 1:1 is added to the mixer in step (2) three times in sequence, and stirred for 20 minutes each time.

[0063] (4) After the powder in step (3) is stirred, 0.10 parts of octylsilane is added thereto and stirring is continued for 20 minutes before discharging the material. After vacuum degassing is completed, the required thermal conductive silicone grease is obtained.

[0064] Comparative Example 1

[0065] A thermally conductive silicone grease capable of high temperature ceramicization is prepared by the following method:

[0066] (1) Add 20 parts of the boron-modified methyl silicone oil with a viscosity of 50 cp of Example 1 and 0.05 parts of octylsilane into a blender and stir evenly;

[0067] (2) 100 parts of ordinary spherical alumina powder (non-ceramic alumina) (particle size of 5 μm) were added to the mixer in step (1) in three portions, and stirred for 20 minutes each time.

[0068] (3) After the powder in step (2) is stirred, 0.05 parts of octylsilane is added thereto and stirring is continued for 20 minutes before discharging the material. After vacuum degassing is completed, the required thermal conductive silicone grease is obtained.

[0069] Comparative Example 2

[0070] A thermally conductive silicone grease capable of high temperature ceramicization is prepared by the following method:

[0071] (1) Add 40 parts of phenyl silicone oil with a viscosity of 50 cp and 0.05 parts of octylsilane into a blender and stir evenly;

[0072] (2) 50 portions of ceramic zinc oxide powder (particle size 20 μm) were added to the mixer in step (1) three times in sequence, and stirred for 20 minutes each time.

[0073] (3) After the powder in step (2) is stirred, 0.05 parts of octylsilane is added thereto and stirring is continued for 20 minutes before discharging the material. After vacuum degassing is completed, the required thermal conductive silicone grease is obtained.

[0074] Comparative Example 3

[0075] A thermally conductive silicone grease capable of high temperature ceramicization is prepared by the following method:

[0076] (1) Add 20 parts of methyl silicone oil with a viscosity of 50 cp and 0.05 parts of octylsilane into a blender and stir evenly;

[0077] (2) 80 parts of ceramicized aluminum oxide with a particle size of 5 μm and ceramicized zinc oxide powder with a particle size of 20 μm are added to the mixer in step (1) in a ratio of 1:1 of aluminum oxide to zinc oxide three times, and stirred for 20 minutes each time.

[0078] (3) After the powder in step (2) is stirred, 0.05 parts of octylsilane is added thereto and stirring is continued for 20 minutes before discharging the material. After vacuum degassing is completed, the required thermal conductive silicone grease is obtained.

[0079] Performance testing and result analysis:

[0080] The above embodiments and comparative examples were coated on 20 mm × 20 mm aluminum plates, and their thermal conductivity before and after high temperature (150°C, 24 h) was tested according to ISO22007.2-2015 standard, and the state of the silicone grease after high temperature was observed. The state before and after high temperature is shown in the figure. Figure 1-4 The states and thermal conductivity before and after high temperature are shown in Table 1 below:

[0081] Table 1:

[0082]

[0083]

[0084] From the comparison in Table 1, it can be seen that the state of Examples 1-4 is transformed from a paste to a ceramic state after high temperature, and the thermal conductivity of the thermal conductive silicone grease in the ceramic state is also significantly improved. The state of the silicone grease in Comparative Examples 1-3 remains unchanged after high temperature, but the thermal conductivity of the thermal conductive silicone grease decreases to varying degrees after high temperature. Figure 1-4 It can be seen that after the silicone grease of the comparative example is subjected to high temperature, oily substances are precipitated around its surface, while the surfaces of Examples 1-4 remain unchanged. This is because the silicone grease is ceramicized, so that the surface of the silicone grease becomes tightly attached to the surface of the substrate.

[0085] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A high temperature ceramic thermal conductive silicone grease, characterized in that: The thermal conductive silicone grease is composed of the following raw material components in terms of mass fraction: 10-30 parts of boron-modified methyl silicone oil; 50-150 parts of ceramic thermal conductive filler; Octylsilane 0.05-0.20 parts.

2. The high temperature ceramic thermal conductive silicone grease according to claim 1, characterized in that: The preparation method of the boron-modified methyl silicone oil is: Boric acid and polyol are subjected to esterification reaction to generate boric ester, the boric ester and hydrogen-containing silicone oil are added to a reaction kettle and mixed evenly, and then a platinum catalyst is added, the temperature is raised to 80-150° C., the reaction is performed for 1.5-3.5 hours, and then the boron-modified methyl silicone oil is obtained through washing and distillation.

3. The high temperature ceramic thermal conductive silicone grease according to claim 2, characterized in that: The structural formula of the boric acid is: B(OH)3R; wherein R is any one selected from methyl, ethyl, and propyl.

4. The high temperature ceramic thermal conductive silicone grease according to claim 2, characterized in that: The hydrogen content of the hydrogen-containing silicone oil is 0.1-0.5wt% and the viscosity is 50-300cp.

5. The high temperature ceramic thermal conductive silicone grease according to claim 2, characterized in that: The mass ratio of the boric acid ester to the hydrogen-containing silicone oil is 0.5-1.5:5-8.

6. The high temperature ceramic thermal conductive silicone grease according to claim 2, characterized in that: The platinum catalyst is chloroplatinic acid; based on the total number of components of the reaction system containing boron-modified methyl silicone oil being 100 parts, the chloroplatinic acid is 0.05-0.15 parts.

7. The high temperature ceramic thermal conductive silicone grease according to claim 1, characterized in that: The ceramicizable thermally conductive filler is one or more of ceramicizable aluminum oxide, ceramicizable zinc oxide, ceramicizable aluminum powder, and ceramicizable copper powder; and the particle size of the ceramicizable thermally conductive filler is 5-20 um.

8. The high temperature ceramic thermal conductive silicone grease according to claim 1, characterized in that: The octylsilane is n-octyltriethoxysilane.

9. The method for preparing high temperature ceramic thermal conductive silicone grease according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Add boron-modified methyl silicone oil and 1 / 2 of octylsilane into a mixer and stir evenly; S2, adding the ceramicized thermally conductive filler into the above mixer three times and stirring; S3, adding 1 / 2 of octylsilane into the above mixer and stirring, then discharging the material, and after vacuum degassing, obtaining a high temperature ceramic thermal conductive silicone grease.

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