An organosilicon heat-conducting coating, its preparation method and application

Abstract

The present invention discloses an organosilicon heat-conducting coating, a preparation method thereof and an application thereof. The preparation raw materials include, by weight fraction: 6-10 parts of a first vinyl siloxane resin, 2-6 parts of a second vinyl siloxane resin, 1-3 parts of a hydrogen-containing silicone oil, 6-8 parts of fumed silica, 0.5-0.8 part of a platinum catalyst, 0.8-1.5 parts of a silane coupling agent, 12-25 parts of carbon nanotubes, 20-30 parts of boron nitride, and 30-50 parts of aluminum nitride; wherein the viscosity of the first vinyl siloxane resin is 300-800 cps / 25 °C; the viscosity of the second vinyl siloxane resin is 2000-5000 cps / 25 °C; and the hydrogen content of the hydrogen-containing silicone oil is 8-12 mmol / g. The coating prepared by using the organosilicon heat-conducting coating not only has excellent heat conductivity, adhesion, water-boiling resistance and anti-aging properties, but is also easy to construct and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal conductive coatings, and in particular to an organosilicon thermal conductive coating and a preparation method and application thereof. Background Art

[0002] With the advancement of new energy lithium-ion battery technology, lithium-ion batteries are becoming increasingly widely used. Power battery modules are composed of multiple cylindrical lithium-ion batteries. During the charging and discharging process, a large amount of heat is generated. Good thermal conductive materials are needed between the batteries to fully dissipate the heat and ensure battery performance and safety.

[0003] In related technologies, the main methods to solve the heat dissipation between batteries include the use of alumina gel and thermally conductive silicone gel. Compared with traditional heat dissipation substrates, they can reduce air gaps (the thermal conductivity of air is very low, only 0.023W / (m·K)), which helps to achieve relatively good heat dissipation effects (less than 10W / (m·K)). However, this type of heat dissipation material is usually two-component and is constructed using a double-tube structural adhesive, which can easily cause inaccurate distribution ratios of components A and B, resulting in oil leakage problems. At the same time, this type of heat dissipation material has poor moisture resistance and aging resistance. For example, alumina gel is sensitive to moisture and is prone to performance degradation in humid environments, affecting its stability and long-term use effect. Thermally conductive silicone gel is very prone to aging and brittleness when used at high temperatures for a long time or exposed to air, affecting its thermal conductivity.

[0004] Based on this, there is an urgent need for a silicone coating that has high thermal conductivity, moisture resistance, and aging resistance, and is easy to construct. Summary of the invention

[0005] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention provides an organosilicon thermally conductive coating, its preparation method, and its application. The coating produced using this organosilicon thermally conductive coating exhibits excellent thermal conductivity, with a thermal conductivity coefficient exceeding 12 W / (m·K). The coating also exhibits excellent adhesion, water boiling resistance, and aging resistance, and is easy to apply. Its application in power battery modules enables rapid heat dissipation, thereby ensuring battery performance and safety, and has broad application prospects.

[0006] In a first aspect of the present invention, there is provided an organosilicon thermal conductive coating, wherein the raw materials for its preparation include, in parts by weight:

[0007] 6-10 parts of a first vinyl silicone resin, 2-6 parts of a second vinyl silicone resin, 1-3 parts of hydrogenated silicone oil, 6-8 parts of fumed silica, 0.5-0.8 parts of a platinum catalyst, 0.8-1.5 parts of a silane coupling agent, 12-25 parts of carbon nanotubes, 20-30 parts of boron nitride, and 30-50 parts of aluminum nitride;

[0008] Among them, the viscosity of the first vinyl silicone resin is 300 - 800 cps / 25°C; the viscosity of the second vinyl silicone resin is 2000 - 5000 cps / 25°C; the hydrogen content of the hydrogen-containing silicone oil is 8 - 12 mmol / g.

[0009] It can be understood that cps / 25°C refers to the viscosity measured at 25°C.

[0010] The silicone thermal conductive coating of the embodiment of the present invention has at least the following beneficial effects:

[0011] (1) The present invention discovers that by combining silicone resins with different viscosities, it helps to enhance the adhesion of the coating and the encapsulation of powder materials (such as thermal conductive fillers), enabling the prepared coating to have an excellent and stable network structure, thereby achieving higher thermal conductivity and better adhesion effect.

[0012] (2) By screening and optimizing the hydrogen content in the hydrogen-containing silicone oil of the silicone thermal conductive coating, the present invention discovers that when its hydrogen content is 8 - 12 mmol / g, it undergoes a free radical addition reaction with the first vinyl silicone resin and the second vinyl silicone resin under the action of a platinum catalyst to form a network cross-linked structure with excellent stability, which helps to improve the adhesion of the formed thermal conductive coating to the substrate, and the water boiling resistance and anti-aging performance are also significantly improved. When the hydrogen content in the hydrogen-containing silicone oil is too high or too low, its comprehensive performance decreases to varying degrees, presumably related to low cross-linking degree or uneven cross-linked structure.

[0013] (3) The present invention innovatively proposes using carbon nanotubes as thermal conductive materials to prepare a high thermal conductive coating by combining them with conventional boron nitride and aluminum nitride thermal conductive fillers. Carbon nanotubes have excellent thermal conductivity, but carbon nanotubes are prone to oxidation in a high-temperature oxygen-containing environment, resulting in poor anti-aging performance. The present invention discovers that combining them with boron nitride and aluminum nitride, and under the encapsulation of the network structure formed by the silicone resin, helps to achieve better anti-aging effect while enhancing thermal conductivity.

[0014] In some embodiments of the present invention, the diameter of the carbon nanotubes is 1 - 20 nm, and the length is 10 - 30 μm.

[0015] In some embodiments of the present invention, the diameter of the carbon nanotubes is 1 - 2 nm, and the length is 10 - 30 μm.

[0016] In some embodiments of the present invention, the particle size of the boron nitride is 50 - 100 nm.

[0017] In some embodiments of the present invention, the particle size of the aluminum nitride is 40 - 60 μm.

[0018] The silicone thermal conductive coating of the present invention is combined with thermal conductive fillers of different particle sizes, wherein large particle size aluminum nitride (40 - 60 μm) is used as the thermal conductive channel, nano-sized boron nitride (50 - 100 nm) is filled in the gaps, and carbon nanotubes are added simultaneously to form a three-dimensional network, achieving a significant improvement in thermal conductivity.

[0019] The present invention discovers that compared with small particle size thermal conductive fillers (such as boron nitride), large particle size filler aluminum nitride has less interfacial contact in the silicone matrix, lower interfacial thermal resistance, and better thermal conductivity. However, it is difficult to form a close packing between thermal conductive fillers with too large particle sizes, and by combining small particle size thermal conductive fillers (such as carbon nanotubes, boron nitride), heat transfer can be further effectively promoted, thereby obtaining good thermal conductivity.

[0020] In some embodiments of the present invention, the carbon nanotubes are selected from one or a combination of single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0021] The present invention discovers through experiments that in the coating system of the present invention, single-walled carbon nanotubes have better thermal conductivity than multi-walled carbon nanotubes. It is speculated that this is because the structure of single-walled carbon nanotubes is single, and its thermal conductivity is mainly dominated by phonons (lattice vibrations) inside the tube, and heat is rapidly transferred through the propagation of phonons; while the thermal conductivity of multi-walled carbon nanotubes is affected by the interlayer effect, and there is thermal resistance at the interface between each layer of nanotubes, especially at low temperatures, the interlayer thermal resistance is more significant. Therefore, the thermal conductivity is slightly worse than that of single-walled carbon nanotubes, but generally speaking, the coatings prepared therefrom still have excellent thermal conductivity.

[0022] In some embodiments of the present invention, the weight ratio of the carbon nanotubes, the boron nitride, and the aluminum nitride is 1:1 - 2:2 - 4.

[0023] In some embodiments of the present invention, the first vinyl siloxane resin is methyl vinyl siloxane resin.

[0024] In some embodiments of the present invention, the vinyl content of the first vinyl siloxane resin is 0.02 - 0.4 mmole / gm.

[0025] In some embodiments of the present invention, the second vinyl siloxane resin is a modified methyl vinyl siloxane resin, and the active groups of the modified methyl vinyl siloxane resin include one or several of hydroxyl groups and epoxy groups.

[0026] In some embodiments of the present invention, the vinyl content of the second vinyl siloxane resin is 0.03 - 0.5 mmole / gm.

[0027] In some embodiments of the present invention, the hydrogen-containing silicone oil is Andisil XL1342 of American Ambia Specialty Resins.

[0028] In some embodiments of the present invention, the silane coupling agent is γ-aminopropyltriethoxysilane, and the trade name is Dow Corning KH-550.

[0029] In some embodiments of the present invention, the preparation raw materials further include 0.1-0.5 parts of a dispersant and 0.2-0.4 parts of an alkynol inhibitor.

[0030] In some embodiments of the present invention, the alkynol inhibitor includes 3,7,11-trimethyldodec-3-yn-3-ol.

[0031] Alkynol inhibitors have a lower boiling point and a faster evaporation rate compared to ester and amine inhibitors. They can evaporate quickly during the baking process, thus losing their function of inhibiting the curing of the coating and enabling the coating to fully crosslink. However, 3,7,11-trimethyldodec-3-yn-3-ol used in the present invention has high stability and can maintain the product stability at a high temperature of 40 °C without crosslinking.

[0032] In a second aspect of the present invention, there is provided a method for preparing the organosilicon thermal conductive coating according to the first aspect of the present invention, which includes mixing the preparation raw materials to obtain the coating.

[0033] In some embodiments of the present invention, the method for preparing the organosilicon thermal conductive coating includes the following steps:

[0034] S1: Weigh the first vinyl silicone resin, the second vinyl silicone resin, the hydrogen-containing silicone oil, the alkynol inhibitor, the silane coupling agent, and the dispersant according to the weight parts, and mix them evenly to obtain a first mixture;

[0035] S2: Weigh the fumed silica, the carbon nanotubes, the boron nitride, and the aluminum nitride according to the weight parts, add them to the first mixture, and after mixing treatment, obtain a second mixture;

[0036] S3: Add the platinum catalyst to the second mixture, and then it can be obtained after reaction.

[0037] In some embodiments of the present invention, in step S1, the stirring speed of the mixing is 600-800 r / min, and the time is 5-10 min.

[0038] In some embodiments of the present invention, in step S2, the mixing treatment includes stirring and ultrasonic treatment.

[0039] In some embodiments of the present invention, in step S2, the stirring speed is 1500-2000 r / min, and the time is 15-25 min.

[0040] The third aspect of the present invention provides an organosilicon thermal conductive coating, which is prepared by curing the organosilicon thermal conductive coating described in the first aspect of the present invention.

[0041] A fourth aspect of the present invention provides use of the organic silicon thermal conductive coating as described in the first aspect of the present invention in preparing a thermal conductive material.

[0042] Other features and advantages of the present invention will be set forth in the description that follows. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0044] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.

[0045] In the description of the present invention, the reference term "and / or" includes all and any combinations of one or more of the associated listed items.

[0046] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0047] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0048] Example 1:

[0049] This example provides a silicone heat-conducting coating and a preparation method thereof. By weight, the raw materials for preparing the silicone heat-conducting coating in this example are shown in Table 1.

[0050] Table 1: Raw Materials for Preparing the Silicone Heat-Conducting Coating in Example 1

[0051]

[0052] Among them, the first vinyl siloxane resin is methyl vinyl siloxane resin, its viscosity at 25 °C is 400 cps, and the vinyl content is 0.03 mmole / gm. It is purchased from Shanghai Jushi Chemical Co., Ltd. with the product number 921; the second vinyl siloxane resin is hydroxy-modified methyl vinyl siloxane resin, its viscosity at 25 °C is 3000 cps, and the vinyl content is 0.04 mmole / gm. It is purchased from Shanghai Jushi Chemical Co., Ltd. with the product number 671; the hydrogen content of the hydrogen-containing silicone oil is 8.6 mmole / gm. It is purchased from Ambia Special Silicone (Nantong) Co., Ltd. with the product number Andisil XL1342; the dispersant is purchased from AG-151 of Zhongtai Lianhua New Materials, and the brand of the fumed silica is Evonik Degussa R972; the brand of the platinum catalyst is Shin-Etsu CAT-PL-56; γ-aminopropyltriethoxysilane is a silane coupling agent with the brand Dow Corning KH-550, and 3,7,11-trimethyldodec-3-yn-3-ol (abbreviation TMDO) is an inhibitor, purchased from Forsman Company (Beijing) with the product number 9401003.

[0053] The above carbon nanotubes are single-walled carbon nanotubes with a diameter of 1 - 2 nm and a length of 10 - 30 μm; the boron nitride is nano-spherical boron nitride with a particle size of 50 - 100 nm, purchased from Shanghai Yaotian New Material Technology Co., Ltd.; the particle size of aluminum nitride is about 40 - 60 μm, purchased from Shanghai Yaotian New Material Technology Co., Ltd.

[0054] The preparation method of the above silicone heat-conducting coating includes the following steps:

[0055] S1. According to the above weight parts, weigh the above first vinyl siloxane resin, second vinyl siloxane resin, hydrogen-containing silicone oil, 3,7,11-trimethyldodec-3-yn-3-ol, γ-aminopropyltriethoxysilane and dispersant, mix them, and stir at a stirring speed of 600 - 800 r / min for 5 - 10 min to form a uniform colloid, that is, the first mixture;

[0056] S2. Weigh fumed silica, carbon nanotubes, boron nitride, and aluminum nitride according to the above weight parts, add them to the above first mixture, disperse them at a stirring speed of 1500 - 2000 r / min for 20 min, and then ultrasonically treat them for 25 min under the condition of 750 W to make them fully mixed, obtaining a second mixture;

[0057] S3. Add a platinum catalyst to the above second mixture, mix it evenly, and obtain the silicone coating after reaction.

[0058] Example 2:

[0059] This example provides a silicone thermal conductive coating and its preparation method. The difference between this silicone thermal conductive coating and that of Example 1 is that single-walled carbon nanotubes are replaced by multi-walled carbon nanotubes, and the remaining preparation raw materials are the same.

[0060] According to weight parts, the preparation raw materials of the silicone thermal conductive coating in this example are shown in Table 2.

[0061] Table 2: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Example 2

[0062]

[0063] Among them, the first vinyl silicone resin is methyl vinyl silicone resin, its viscosity at 25°C is 400 cps, and the vinyl content is 0.03 mmole / gm. It is purchased from Shanghai Jiushi Chemical Co., Ltd., and the product number is 921; the second vinyl silicone resin is hydroxy-modified methyl vinyl silicone resin, its viscosity at 25°C is 3000 cps, and the vinyl content is 0.04 mmole / gm. It is purchased from Shanghai Jiushi Chemical Co., Ltd., and the product number is 671; the hydrogen content of the hydrogen-containing silicone oil is 8.6 mmole / gm. It is purchased from Anbia Special Silicone (Nantong) Co., Ltd., and the product number is Andisil XL1342; the dispersant is purchased from AG-151 of Zhongtai Lianhua New Materials; the grade of fumed silica is Evonik Degussa R972; the grade of the platinum catalyst is Shin-Etsu CAT-PL-56; γ-aminopropyltriethoxysilane is a silane coupling agent, and its grade is Dow Corning KH-550. 3,7,11-trimethyldodec-3-yn-3-ol (abbreviation: TMDO) is an inhibitor, purchased from Forsman Company (Beijing), and the product number is 9401003.

[0064] The above carbon nanotubes are multi-walled carbon nanotubes, with a diameter of 3 - 15 nm and a length of 15 - 30 μm; the boron nitride is nano-spherical boron nitride, with a particle size of 50 - 100 nm, purchased from Shanghai Yaotian New Materials Technology Co., Ltd.; the particle size of aluminum nitride is about 40 - 60 μm, purchased from Shanghai Yaotian New Materials Technology Co., Ltd.

[0065] The preparation method of the above-mentioned silicone heat-conducting coating comprises the following steps:

[0066] S1. Weigh the above-mentioned first vinyl silicone resin, second vinyl silicone resin, hydrogen-containing silicone oil, 3,7,11-trimethyl dodec-3-yne-3-ol, γ-aminopropyltriethoxysilane and dispersant according to the above weight parts, mix them, and stir at a stirring speed of 600-800 r / min for 5-10 min to form a uniform colloid, namely the first mixture;

[0067] S2. Weigh fumed silica, carbon nanotubes, boron nitride and aluminum nitride according to the above weight parts, add them to the above first mixture, disperse them at a stirring speed of 1500-2000 r / min for 20 min, and then ultrasonically treat them for 25 min under the condition of 750 W to make them fully mixed to obtain the second mixture;

[0068] S3. Add a platinum catalyst to the above second mixture, mix it evenly, and obtain the silicone coating after reaction.

[0069] Example 3:

[0070] This example provides a silicone heat-conducting coating and its preparation method. The difference between this silicone heat-conducting coating and that of Example 1 lies in the different addition ratios of carbon nanotubes, boron nitride and aluminum nitride.

[0071] Calculated by weight parts, the raw materials for preparing the silicone heat-conducting coating in this example are shown in Table 3.

[0072] Table 3: Raw materials for preparing the silicone heat-conducting coating in Example 3

[0073]

[0074] Among them, the first vinyl siloxane resin is methyl vinyl siloxane resin, with a viscosity of 400 cps at 25°C and a vinyl content of 0.03 mmole / gm. It is purchased from Shanghai Jushi Chemical Co., Ltd. with the product number 921; the second vinyl siloxane resin is hydroxyl-modified methyl vinyl siloxane resin, with a viscosity of 3000 cps at 25°C and a vinyl content of 0.04 mmole / gm. It is purchased from Shanghai Jushi Chemical Co., Ltd. with the product number 671; the hydrogen content of the hydrogen-containing silicone oil is 8.6 mmole / gm. It is purchased from Anbia Special Organosilicon (Nantong) Co., Ltd. with the product number Andisil XL1342; the dispersant is purchased from AG-151 of Zhongtai Lianhua New Materials; the grade of the fumed silica is Evonik Degussa R972; the grade of the platinum catalyst is Shin-Etsu CAT-PL-56; γ-aminopropyltriethoxysilane is a silane coupling agent with the grade of Dow Corning KH-550, and 3,7,11-trimethyldodec-3-yne-3-ol (abbreviation TMDO) is an inhibitor, purchased from Fosman Company (Beijing) with the product number 9401003.

[0075] The above carbon nanotubes are single-walled carbon nanotubes with a diameter of 1 - 2 nm and a length of 10 - 30 μm; the boron nitride is nano-spherical boron nitride with a particle size of 50 - 100 nm, purchased from Shanghai Yaotian New Material Technology Co., Ltd.; the particle size of aluminum nitride is about 40 - 60 μm, purchased from Shanghai Yaotian New Material Technology Co., Ltd.

[0076] The preparation method of the above-mentioned organosilicon thermal conductive coating includes the following steps:

[0077] S1. Weigh the above-mentioned first vinyl siloxane resin, second vinyl siloxane resin, hydrogen-containing silicone oil, 3,7,11-trimethyldodec-3-yne-3-ol, γ-aminopropyltriethoxysilane and dispersant according to the above weight parts, mix them, and stir at a stirring speed of 600 - 800 r / min for 5 - 10 min to form a uniform colloid, that is, the first mixture;

[0078] S2. Weigh the fumed silica, carbon nanotubes, boron nitride and aluminum nitride according to the above weight parts, add them to the above first mixture, disperse them at a stirring speed of 1500 - 2000 r / min for 20 min, and then ultrasonically treat them for 25 min under the condition of 750 W to make them fully mixed to obtain the second mixture;

[0079] S3. Add the platinum catalyst to the above second mixture, mix it evenly, and obtain the organosilicon coating after reaction.

[0080] Comparative Example 1:

[0081] This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between this silicone thermal conductive coating and that of Example 1 lies in that the addition ratio of the first vinyl silicone resin and the second vinyl silicone resin is adjusted, and the remaining preparation raw materials are the same.

[0082] By weight, the preparation raw materials of the silicone thermal conductive coating in this comparative example are shown in Table 4.

[0083] Table 4: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Comparative Example 1

[0084]

[0085] The preparation method of the above silicone thermal conductive coating refers to the method of Example 1.

[0086] Comparative Example 2:

[0087] This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between this silicone thermal conductive coating and that of Example 1 lies in that the addition ratio of the silane coupling agent γ-aminopropyltriethoxysilane is reduced, and the remaining preparation raw materials are the same.

[0088] By weight, the preparation raw materials of the silicone thermal conductive coating in this comparative example are shown in Table 5.

[0089] Table 5: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Comparative Example 2

[0090]

[0091] The preparation method of the above silicone thermal conductive coating refers to Example 1.

[0092] Comparative Example 3:

[0093] This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between this silicone thermal conductive coating and that of Example 1 lies in that the addition ratios of carbon nanotubes, boron nitride, and aluminum nitride are adjusted, specifically to 1:1:6, and the remaining preparation raw materials are the same.

[0094] By weight, the preparation raw materials of the silicone thermal conductive coating in this comparative example are shown in Table 6.

[0095] Table 6: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Comparative Example 3

[0096]

[0097] The preparation method of the above silicone thermal conductive coating refers to Example 1.

[0098] Comparative Example 4:

[0099] This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between this silicone thermal conductive coating and that of Example 1 lies in that: the addition ratio of the inhibitor (3,7,11-trimethyldodec-3-yne-1-ol) is reduced, and the remaining preparation raw materials are the same.

[0100] By weight, the preparation raw materials of the silicone thermal conductive coating in this comparative example are shown in Table 7.

[0101] Table 7: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Comparative Example 4

[0102]

[0103] The preparation method of the above silicone thermal conductive coating refers to Example 1.

[0104] Comparative Example 5:

[0105] This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between this silicone thermal conductive coating and that of Example 1 lies in that: the hydrogen content in the hydrogen-containing silicone oil is reduced, and the remaining preparation raw materials are the same.

[0106] By weight, the preparation raw materials of the silicone thermal conductive coating in this comparative example are shown in Table 8.

[0107] Table 8: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Comparative Example 5

[0108]

[0109] Among them, the hydrogen content in the hydrogen-containing silicone oil is about 0.5 - 0.8%Wt, and after conversion to molar concentration, it is about 4.95 - 7.94 mmole / gm.

[0110] The preparation method of the above silicone thermal conductive coating refers to the preparation in Example 1.

[0111] Comparative Example 6:

[0112] This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between this silicone thermal conductive coating and that of Example 1 lies in that: the hydrogen content in the hydrogen-containing silicone oil is increased, and the remaining preparation raw materials are the same.

[0113] By weight, the preparation raw materials of the silicone thermal conductive coating in this comparative example are shown in Table 9.

[0114] Table 9: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Comparative Example 6

[0115]

[0116] Among them, the hydrogen content in the hydrogen-containing silicone oil is about 1.4 - 1.6%Wt, and after conversion to molar concentration, it is about 13.88 - 15.85 mmole / gm.

[0117] The preparation method of the above silicone heat-conducting coating is prepared with reference to Example 1.

[0118] Comparative Example 7:

[0119] This comparative example provides a silicone heat-conducting coating and its preparation method. The difference between this silicone heat-conducting coating and that of Example 1 is that: the fumed silica is replaced by conventional silica powder, and the rest of the preparation raw materials are the same.

[0120] By weight, the preparation raw materials of the silicone heat-conducting coating in this comparative example are shown in Table 10.

[0121] Table 10: Preparation raw materials of the silicone heat-conducting coating in Comparative Example 7

[0122]

[0123] Among them, the average particle size of the silica is 3.4 - 4.0 μm, purchased from Grace Company, and the product number is C803.

[0124] The preparation method of the above silicone heat-conducting coating is prepared with reference to Example 1.

[0125] Comparative Example 8:

[0126] This comparative example provides a silicone heat-conducting coating and its preparation method. The difference between this silicone heat-conducting coating and that of Example 1 is that: the second vinyl siloxane resin is replaced by a siloxane resin with a viscosity of 65000 cps / 25°C, and the rest of the preparation raw materials are the same.

[0127] By weight, the preparation raw materials of the silicone heat-conducting coating in this comparative example are shown in Table 11.

[0128] Table 11: Preparation raw materials of the silicone heat-conducting coating in Comparative Example 8

[0129]

[0130] Among them, the viscosity of the second vinyl siloxane resin at 25°C is 65000 cps, the vinyl content is 0.03 mmole / gm, purchased from Ambia Specialty Silicones (Nantong) Co., Ltd., and the brand is Andisil® VS 65000.

[0131] The preparation method of the above silicone heat-conducting coating is prepared with reference to Example 1.

[0132] Comparative Example 9:

[0133] This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between this silicone thermal conductive coating and that of Example 1 lies in that the carbon nanotubes are replaced with an equal amount of boron nitride (i.e., no carbon nanotubes are added), and the remaining preparation raw materials are the same.

[0134] By weight, the preparation raw materials of the silicone thermal conductive coating in this comparative example are shown in Table 12.

[0135] Table 12: Preparation Raw Materials of the Silicone Thermal Conductive Coating in Comparative Example 9

[0136]

[0137] The preparation method of the above silicone thermal conductive coating refers to Example 1.

[0138] Test Example 1:

[0139] This test example conducts a thermal conductivity test on the silicone thermal conductive coatings prepared in the above Examples 1-3 and Comparative Examples 1-9. The test method specifically refers to the ASTM D 5470 test standard.

[0140] The test results are shown in Table 13.

[0141] Table 13: Thermal Conductivity Test Results

[0142]

[0143] The above results show that the thermal conductive coating prepared with the silicone thermal conductive coating of the present invention exhibits excellent thermal conductivity, with a thermal conductivity greater than 12 W / (m·K). Using it in the power battery module can quickly disperse heat, thereby ensuring the performance and safety of the battery.

[0144] Furthermore, when adjusting the raw material components (such as Comparative Examples 1-9), the thermal conductivity has decreased to varying degrees. Among them, when the addition ratios of carbon nanotubes, boron nitride, and aluminum nitride in the coating system are adjusted to 1:1:6 (such as Comparative Example 3), its thermal conductivity has decreased significantly, only being 10.5 W / (m·K). It is speculated that as the addition ratio of aluminum nitride (particle size 40-60 μm) increases, the large-particle-size thermal conductive fillers dominate the entire filler system, and it is difficult for the thermal conductive fillers to form a close packing, which is not conducive to the formation of a thermal conduction path.

[0145] Furthermore, it's worth noting that excessively high siloxane resin viscosity (as in Comparative Example 1) and excessively high hydrogen content in the hydrogenated silicone oil (as in Comparative Example 6) also hinder improvements in thermal conductivity. This is presumably because the thermal conductivity of the coating primarily depends on the arrangement and packing density of the various components within the thermally conductive coating (e.g., siloxane resin, thermally conductive fillers, and other additives). Excessively high siloxane resin viscosity can lead to uneven filler dispersion or large interparticle gaps within the coating. These microstructural inhomogeneities can hinder heat conduction and reduce thermal conductivity. Furthermore, excessively high hydrogen content in the hydrogenated silicone oil can increase the thermal expansion coefficient of the material, as hydrogen atoms are low-quality thermal conductors. This increase in thermal expansion can increase coating instability, disrupting the continuity of thermal conduction, particularly at high temperatures.

[0146] Test Example 2:

[0147] This test example conducted adhesion test, water boiling test and aging test on the organic silicone thermal conductive coatings prepared in Examples 1-3 and Comparative Examples 1-9, and evaluated their ease of construction, wherein:

[0148] (1) Adhesion test: Conducted in accordance with GB9286-2021 standard. Grade 0 means the cutting edge is completely smooth and there is no shedding within the grid; Grade 1 means there is a little coating shedding at the intersection of the cuts, but the affected cross-cut area is no more than 5%; Grade 2 means there is coating shedding at the intersection of the cuts and / or along the cut edges, and the affected cross-cut area is greater than 5% but not more than 15%.

[0149] (2) Boiling test: Apply the coating on a metal sheet, dry it at 60°C for 60 minutes, then soak the prepared coating in boiling water (about 100°C) for 120 minutes and observe the surface condition of the coating.

[0150] (3) Aging test: The prepared coating was placed under ultraviolet light with a wavelength of 420 nm and a light intensity of 0.80 W / m 2 After being stored for a certain period of time under the conditions, there is no abnormality on the coating surface and the adhesion is OK.

[0151] (4) Construction performance evaluation: Evaluation is based on the difficulty of coating.

[0152] The test results are shown in Table 14.

[0153] Table 14: Related performance test results

[0154]

[0155] The above results show that the organosilicon thermal conductive coating prepared using the formulation of the present invention has excellent adhesion, water boiling resistance and aging resistance, and has moderate viscosity and is easy to apply. Compared with Example 1, Example 3 increases the amount of carbon nanotubes while reducing the amount of boron nitride while keeping the total filler unchanged. The results show that its aging resistance is slightly reduced, which is presumably related to the oxidation of the carbon nanotubes. Under the illumination of a xenon lamp, the surface temperature of the coating increases, prompting oxygen to react with the surface of the carbon nanotubes, affecting the aging resistance.

[0156] Compared to Example 1, Comparative Example 1 increased the relative content of the second vinyl silicone resin, while Comparative Example 8 further increased the viscosity of the second vinyl silicone resin to 65,000 cps / 25°C. The results showed that the coating's fluidity during application deteriorated, leading to difficulties in application. Notably, the coating produced using the coating from Comparative Example 8 partially detached or peeled during the water boiling test. This is presumably due to the inherent hydrophilicity of the silicone resin. When the viscosity of the silicone resin increases, it tends to absorb moisture, thus affecting its adhesion stability.

[0157] Compared with Example 1, Comparative Example 2 reduced the addition ratio of γ-aminopropyltriethoxysilane to thermally conductive fillers (carbon nanotubes, boron nitride, and aluminum nitride) from 1:80 to 1:160. The test results showed that the adhesion, boiling resistance, and aging resistance of the thermally conductive coating were significantly reduced. It is speculated that the reduction of γ-aminopropyltriethoxysilane resulted in uneven dispersion of the thermally conductive filler in the silicone material, ultimately causing various performance properties to decline to varying degrees.

[0158] Compared to Example 1, Comparative Example 3 adjusted the ratio of carbon nanotubes, boron nitride, and aluminum nitride to 1:1:6, and Comparative Example 9 replaced the carbon nanotubes with an equal amount of boron nitride. The results showed that the adhesion, boiling resistance, and aging resistance of Comparative Example 3 remained unchanged, but the aging resistance of Comparative Example 9 declined. This is presumably due to the instability of the coating network structure caused by the lack of carbon nanotubes, which in turn affected the aging resistance. This shows that adding a certain proportion of carbon nanotubes to the thermally conductive coating system of the present invention also helps improve structural stability, thereby enhancing aging resistance.

[0159] Compared with Example 1, in Comparative Example 4, the addition amount of the inhibitor was reduced, and the result showed that the construction life became shorter. In Comparative Example 5, the hydrogen content in the hydrogen-containing silicone oil was reduced, while in Comparative Example 6, the hydrogen content in the hydrogen-containing silicone oil was increased. The results showed that the adhesion, water boiling resistance and anti-aging performance of the prepared thermal conductive coating were significantly deteriorated. It was speculated that the lower hydrogen content led to a decrease in the efficiency of the hydrosilylation reaction, affecting the crosslinking degree between the silicone resin and the hydrogenated silicone oil, making it difficult for the coating to form a relatively dense three-dimensional network structure, reducing the encapsulation of the thermal conductive filler, and ultimately resulting in poor performance. When the hydrogen content was high, due to over-crosslinking or uneven crosslinking structure, a relatively dense crosslinking structure might be formed on the surface of the thermal conductive coating, resulting in the coating becoming brittle and hard, lacking sufficient flexibility and ductility, and ultimately reducing the interaction force between the coating and the substrate, leading to a decrease in adhesion.

[0160] Compared with Example 1, in Comparative Example 7, the fumed silica was replaced with conventional silica powder. The result showed that the construction difficulty of the coating increased and the anti-aging property also decreased. It was speculated that due to the relatively large particle size and poor dispersibility of the conventional silica powder, the viscosity of the coating increased, the fluidity became poor, and it was difficult to coat evenly during construction. The decrease in the anti-aging property was speculated to be related to its uneven distribution.

[0161] The above results showed that the silicone thermal conductive coating prepared with the formula of the present invention had excellent adhesion, water boiling resistance and anti-aging properties, and was easy to construct. After replacing, adjusting and omitting the component ratios thereof, the corresponding properties decreased to varying degrees, which was not conducive to the improvement of its comprehensive performance.

[0162] In summary, the present invention provides a silicone thermal conductive coating, its preparation method and application. By matching the thermal conductive filler and silicone resin and other components in the silicone thermal conductive coating, the present invention solves the problems of difficult construction and too low thermal conductivity of the current thermal conductive coating. The coating prepared with the silicone thermal conductive coating of the present invention not only has excellent thermal conductivity, and the thermal conductivity can reach more than 12 W / (m·K), but also has excellent adhesion, water boiling resistance and anti-aging properties, and is easy to construct. Using it in the power battery module can achieve rapid heat dissipation, thus ensuring the performance and safety of the battery, and has a wide application prospect.

[0163] The above has described the embodiments of the present invention in detail, but the present invention is not limited to the above embodiments. Various changes can be made without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art to which the present invention pertains. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A silicone thermal conductive coating, characterized in that, By weight parts, the preparation raw materials include: 6 - 10 parts of first vinyl silicone resin, 2 - 6 parts of second vinyl silicone resin, 1 - 3 parts of hydrogen-containing silicone oil, 6 - 8 parts of fumed silica, 0.5 - 0.8 parts of platinum catalyst, 0.8 - 1.5 parts of silane coupling agent, 12 - 25 parts of carbon nanotubes, 20 - 30 parts of boron nitride, 30 - 50 parts of aluminum nitride; Among them, the viscosity of the first vinyl silicone resin is 300 - 800 cps / 25°C; the viscosity of the second vinyl silicone resin is 2000 - 5000 cps / 25°C; the hydrogen content of the hydrogen-containing silicone oil is 8 - 12 mmol / g; The diameter of the carbon nanotubes is 1 - 20 nm, the length is 10 - 30 μm, the particle size of the boron nitride is 50 - 100 nm, and the particle size of the aluminum nitride is 40 - 60 μm; The weight parts ratio of the carbon nanotubes, the boron nitride and the aluminum nitride is 1:1 - 2:2 - 4.

2. The silicone thermal conductive coating according to claim 1, wherein The carbon nanotubes are selected from one or a combination of single-walled carbon nanotubes and multi-walled carbon nanotubes.

3. The silicone thermal conductive coating according to claim 1, characterized in that The first vinyl silicone resin is methyl vinyl silicone resin.

4. The silicone thermal conductive coating according to claim 1, wherein The second vinyl silicone resin is a modified methyl vinyl silicone resin, and the active groups of the modified methyl vinyl silicone resin include one or several of hydroxyl groups and epoxy groups.

5. The silicone thermal conductive coating according to any one of claims 1 to 4, characterized in that, The preparation raw materials further include 0.1 - 0.5 parts of dispersant and 0.2 - 0.4 parts of alkyne alcohol inhibitor.

6. The silicone thermal conductive coating according to claim 5, wherein The alkyne alcohol inhibitor includes 3,7,11-trimethyldodec-3-yn-1-ol.

7. A method for preparing the silicone heat-conducting coating according to any one of claims 1 to 6, characterized in that, It includes that after mixing the preparation raw materials, it is obtained.

8. A silicone thermal conductive coating, characterized in that, It is obtained by curing the silicone thermal conductive coating according to any one of claims 1 to 6.

9. Use of the silicone thermal conductive coating according to any one of claims 1 to 6 in the preparation of thermal conductive materials.

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