Organic silicon heat-conducting coating as well as preparation method and application thereof

Abstract

The invention discloses an organic silicon heat-conducting coating as well as a preparation method and application thereof. The high-temperature-resistant ceramic material is prepared from the following raw materials in parts by weight: 6-10 parts of first vinyl siloxane resin, 2-6 parts of second vinyl siloxane resin, 1-3 parts of 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 to 800 cps / 25 DEG C; the viscosity of the second vinyl siloxane resin is 2000 to 5000 cps / 25 DEG C; the hydrogen content of the hydrogen-containing silicone oil is 8-12 mmol / g. A coating layer prepared from the organic silicon heat-conducting coating has excellent heat conductivity, adhesive force, boiling resistance and aging resistance, is 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 organic silicon 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 increasingly used. The power battery module is composed of multiple cylindrical lithium batteries. During the charging and discharging process, a large amount of heat will be generated. Good thermal conductive materials need to be used to fill the gaps between the batteries so that the heat can be fully dissipated to ensure the performance and safety of the battery.

[0003] In the related technology, the main methods to solve the heat dissipation between batteries include the use of alumina gel and thermally conductive silicone gel, which can reduce the air gap compared to the traditional heat dissipation substrate (the thermal conductivity of air is very low, only 0.023W / (m·K)), and help achieve a relatively good heat dissipation effect (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 an inaccurate distribution ratio of components A and B, thereby causing 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 a humid environment, affecting its stability and long-term use effect. Thermally conductive silicone gel is very easy to age and become brittle 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, anti-aging properties, and is easy to construct. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an organic silicon thermal conductive coating and a preparation method and application thereof. The coating prepared by using the organic silicon thermal conductive coating has excellent thermal conductivity, and the thermal conductivity coefficient can reach more than 12W / (m·K). At the same time, the coating also has excellent adhesion, boiling resistance and anti-aging properties, and is easy to construct. It can be used in power battery modules to achieve rapid heat dissipation, thereby ensuring the performance and safety of the battery, and has broad application prospects.

[0006] In a first aspect of the present invention, there is provided an organic silicon thermal conductive coating, wherein the raw materials for its preparation include, by weight: 6-10 parts of the first vinyl siloxane resin, 2-6 parts of the second vinyl siloxane resin, 1-3 parts of hydrogenated 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, and 30-50 parts of aluminum nitride; 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; and the hydrogen content of the hydrogen-containing silicone oil is 8-12 mmol / g.

[0007] It will be appreciated that cps / 25°C refers to the viscosity measured at 25°C.

[0008] The organic silicon thermal conductive coating of the embodiment of the present invention has at least the following beneficial effects: (1) The present invention finds that by combining silicone resins of different viscosities, it helps to enhance the adhesion of the coating and the encapsulation of powder (such as thermal conductive filler), so that the prepared coating has an excellent and stable network structure, thereby achieving higher thermal conductivity and better adhesion effect.

[0009] (2) The present invention screens and optimizes the hydrogen content in the hydrogen-containing silicone oil in the silicone thermal conductive coating and finds that when the hydrogen content is 8-12 mmol / g, a free radical addition reaction occurs 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 boiling water resistance and anti-aging properties are also significantly improved. However, when the hydrogen content in the hydrogen-containing silicone oil is too high or too low, its comprehensive performance decreases to varying degrees, which is presumably related to the low degree of cross-linking or uneven cross-linking structure.

[0010] (3) The present invention innovatively proposes to use carbon nanotubes as thermal conductive materials, and to prepare high thermal conductive coatings by combining them with conventional boron nitride and aluminum nitride thermal conductive fillers. Carbon nanotubes have excellent thermal conductivity, but they are easily oxidized in high-temperature oxygen-containing environments, resulting in poor anti-aging performance. The present invention finds that combining them with boron nitride and aluminum nitride, and wrapping them in a network structure formed by silicone resin, can help improve thermal conductivity while achieving better anti-aging effects.

[0011] In some embodiments of the present invention, the carbon nanotubes have a diameter of 1-20 nm and a length of 10-30 μm.

[0012] In some embodiments of the present invention, the carbon nanotubes have a diameter of 1-2 nm and a length of 10-30 μm.

[0013] In some embodiments of the present invention, the particle size of the boron nitride is 50-100 nm.

[0014] In some embodiments of the present invention, the particle size of the aluminum nitride is 40-60 μm.

[0015] The organic silicon thermal conductive coating of the present invention is matched with thermal conductive fillers of different particle sizes, wherein large-particle aluminum nitride (40-60 μm) is used as a thermal conductive channel, nano-sized boron nitride (50-100 nm) is used to fill the gap, and carbon nanotubes are added to form a three-dimensional network, thereby achieving a significant improvement in thermal conductivity.

[0016] The present invention found that compared with small-particle thermal conductive fillers (such as boron nitride), large-particle filler aluminum nitride has less interface contact in the silicone matrix, lower interface thermal resistance, and better thermal conductivity. However, it is difficult for thermal conductive fillers with too large particle sizes to form a tight stack, and by matching with small-particle thermal conductive fillers (such as carbon nanotubes and boron nitride), heat transfer can be further effectively promoted, thereby obtaining good thermal conductivity.

[0017] 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.

[0018] The present invention has found 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 due to the single-walled carbon nanotube structure, its thermal conductivity is mainly dominated by phonons (lattice vibrations) in the tube, and heat is quickly transferred through the propagation of phonons; while the thermal conductivity of multi-walled carbon nanotubes will be affected by the interlayer effect, and there will be thermal resistance at the interface between each layer of nanotubes, especially at low temperatures, the thermal resistance between layers is more significant. Therefore, the thermal conductivity is slightly worse than that of single-walled carbon nanotubes, but overall, the coating prepared therefrom still has excellent thermal conductivity.

[0019] 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.

[0020] In some embodiments of the present invention, the first vinyl siloxane resin is a methyl vinyl siloxane resin.

[0021] In some embodiments of the present invention, the first vinyl silicone resin has a vinyl content of 0.02-0.4 mmole / gm.

[0022] In some embodiments of the present invention, the second vinyl silicone resin is a modified methyl vinyl silicone resin, wherein the active groups of the modified methyl vinyl silicone resin include one or more of a hydroxyl group and an epoxy group.

[0023] In some embodiments of the present invention, the second vinyl silicone resin has a vinyl content of 0.03-0.5 mmole / gm.

[0024] In some embodiments of the present invention, the hydrogen-containing silicone oil is Andisil XL1342 produced by Ambia Specialty Resins of the United States.

[0025] In some embodiments of the present invention, the silane coupling agent is γ-aminopropyltriethoxysilane, and the brand is Dow Corning KH-550.

[0026] In some embodiments of the present invention, the preparation raw material further comprises 0.1-0.5 parts of a dispersant and 0.2-0.4 parts of an acetylene alcohol inhibitor.

[0027] In some embodiments of the present invention, the alkynol inhibitor includes 3,7,11-trimethyldodecyn-3-ol.

[0028] Compared with ester and amine inhibitors, acetylene alcohol inhibitors have a lower boiling point and a faster volatilization speed, and can volatilize quickly during the baking process, thereby losing the effect of inhibiting the curing of the coating, so that the coating can fully undergo a cross-linking reaction. The 3,7,11-trimethyldodecyne-3-ol used in the present invention has a high stability and can still keep the product stable at a high temperature of 40°C without cross-linking.

[0029] The second aspect of the present invention provides a method for preparing the organic silicon thermal conductive coating according to the first aspect of the present invention, comprising mixing the preparation raw materials to obtain the organic silicon thermal conductive coating.

[0030] In some embodiments of the present invention, the method for preparing the organic silicon thermal conductive coating comprises the following steps: S1. Weigh the first vinyl silicone resin, the second vinyl silicone resin, the hydrogenated silicone oil, the acetylenic alcohol inhibitor, the silane coupling agent and the dispersant in parts by weight, and mix them evenly to obtain a first mixture; S2, weighing the fumed silicon dioxide, the carbon nanotubes, the boron nitride and the aluminum nitride according to weight parts, adding them to the first mixture, and mixing them to obtain a second mixture; S3, adding the platinum catalyst to the second mixture and allowing the mixture to react.

[0031] In some embodiments of the present invention, in step S1, the mixing is stirred at a speed of 600-800 r / min for 5-10 min.

[0032] In some embodiments of the present invention, in step S2, the mixing process includes stirring and ultrasonic treatment.

[0033] 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.

[0034] The third aspect of the present invention provides an organosilicon thermal conductive coating, which is obtained by curing the organosilicon thermal conductive coating described in the first aspect of the present invention.

[0035] The 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 the preparation of a thermal conductive material.

[0036] Other features and advantages of the present invention will be set forth in the description which follows. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments 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.

[0038] When a numerical range is disclosed herein, the above range is considered to be 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 features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0039] 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.

[0040] In the description of the present invention, the description with reference to the terms "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 schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0041] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0042] Embodiment 1: This embodiment provides a silicone thermal conductive coating and a preparation method thereof. The raw materials for preparing the silicone thermal conductive coating of this embodiment are shown in Table 1 in parts by weight.

[0043] Table 1: Raw materials for preparing silicone thermal conductive coating in Example 1

[0044] Among them, the first vinyl silicone resin is a methyl vinyl silicone resin, which has a viscosity of 400 cps at 25°C and a vinyl content of 0.03 mmole / gm, purchased from Shanghai Jiushi Chemical Co., Ltd., with a product number of 921; the second vinyl silicone resin is a hydroxy-modified methyl vinyl silicone resin, which has a viscosity of 3000 cps at 25°C and a vinyl content of 0.04 mmole / gm, purchased from Shanghai Jiushi Chemical Co., Ltd., with a product number of 671; the hydrogen content of the hydrogen-containing silicone oil is 8.6 mmole / gm, purchased from Anbiya Special Silicone (Nantong) Co., Ltd., with a product number of Andisil XL1342; the dispersant was purchased from Zhongtai Lianhua New Materials' AG-151, the brand of fumed silica was Evonik Degussa R972; the brand of platinum catalyst was Shin-Etsu CAT-PL-56; γ-aminopropyltriethoxysilane was the silane coupling agent, the brand was Dow Corning KH-550, and 3,7,11-trimethyldodecyne-3-ol (TMDO for short) was the inhibitor, purchased from Forssman Company (Beijing), the product number was 9401003.

[0045] The above-mentioned 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 Materials Technology Co., Ltd.; the particle size of aluminum nitride is about 40-60 μm, purchased from Shanghai Yaotian New Materials Technology Co., Ltd.

[0046] The preparation method of the above-mentioned organic silicon thermal conductive coating comprises the following steps: S1. Weigh the first vinyl silicone resin, the second vinyl silicone resin, the hydrogenated silicone oil, 3,7,11-trimethyldodecyl-3-ol, γ-aminopropyltriethoxysilane and the dispersant according to the above weight ratios, mix them, and stir them at a stirring speed of 600-800 r / min for 5-10 min to form a uniform colloid, i.e., the first mixture; S2. According to the above weight proportions, fumed silica, carbon nanotubes, boron nitride and aluminum nitride are weighed, added to the above first mixture, dispersed at a stirring speed of 1500-2000 r / min for 20 min, and then ultrasonically treated at 750 W for 25 min to fully mix, to obtain a second mixture; S3, adding platinum catalyst to the second mixture, mixing evenly, and obtaining the organosilicon coating after reaction.

[0047] Embodiment 2: This embodiment provides an organosilicon thermal conductive coating and a preparation method thereof. The difference between the organosilicon thermal conductive coating and Embodiment 1 is that single-walled carbon nanotubes are replaced with multi-walled carbon nanotubes, and the other preparation raw materials are the same.

[0048] The raw materials for preparing the organic silicon thermal conductive coating of this embodiment are shown in Table 2 in parts by weight.

[0049] Table 2: Raw materials for preparing silicone thermal conductive coating in Example 2

[0050] Among them, the first vinyl silicone resin is a methyl vinyl silicone resin, which has a viscosity of 400 cps at 25°C and a vinyl content of 0.03 mmole / gm, purchased from Shanghai Jiushi Chemical Co., Ltd., with a product number of 921; the second vinyl silicone resin is a hydroxy-modified methyl vinyl silicone resin, which has a viscosity of 3000 cps at 25°C and a vinyl content of 0.04 mmole / gm, purchased from Shanghai Jiushi Chemical Co., Ltd., with a product number of 671; the hydrogen content of the hydrogen-containing silicone oil is 8.6 mmole / gm, purchased from Anbiya Special Silicone (Nantong) Co., Ltd., with a product number of Andisil XL1342; dispersant AG-151 purchased from Zhongtai Lianhua New Materials; the brand of fumed silica is Evonik Degussa R972; the brand of platinum catalyst is Shin-Etsu CAT-PL-56; γ-aminopropyltriethoxysilane is the silane coupling agent, the brand is Dow Corning KH-550, 3,7,11-trimethyldodecyne-3-ol (TMDO for short) is the inhibitor, purchased from Forssman Company (Beijing), the product number is 9401003.

[0051] The above-mentioned carbon nanotubes are multi-walled carbon nanotubes with a diameter of 3-15nm and a length of 15-30 μm; the boron nitride is nano-spherical boron nitride with a particle size of 50-100nm, 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.

[0052] The preparation method of the above-mentioned organic silicon thermal conductive coating comprises the following steps: S1. Weigh the first vinyl silicone resin, the second vinyl silicone resin, the hydrogenated silicone oil, 3,7,11-trimethyldodecyl-3-ol, γ-aminopropyltriethoxysilane and the dispersant according to the above weight ratios, mix them, and stir them at a stirring speed of 600-800 r / min for 5-10 min to form a uniform colloid, i.e., the first mixture; S2. According to the above weight proportions, fumed silica, carbon nanotubes, boron nitride and aluminum nitride are weighed, added to the above first mixture, dispersed at a stirring speed of 1500-2000 r / min for 20 min, and then ultrasonically treated at 750 W for 25 min to fully mix, to obtain a second mixture; S3, adding platinum catalyst to the second mixture, mixing evenly, and obtaining the organosilicon coating after reaction.

[0053] Embodiment 3: This embodiment provides an organosilicon thermal conductive coating and a preparation method thereof. The difference between the organosilicon thermal conductive coating and embodiment 1 is that the addition ratios of carbon nanotubes, boron nitride and aluminum nitride are different.

[0054] The raw materials for preparing the organic silicon thermal conductive coating of this embodiment are shown in Table 3 in parts by weight.

[0055] Table 3: Raw materials for preparing organic silicon thermal conductive coating in Example 3

[0056] Among them, the first vinyl silicone resin is a methyl vinyl silicone resin, which has a viscosity of 400 cps at 25°C and a vinyl content of 0.03 mmole / gm, purchased from Shanghai Jiushi Chemical Co., Ltd., with a product number of 921; the second vinyl silicone resin is a hydroxy-modified methyl vinyl silicone resin, which has a viscosity of 3000 cps at 25°C and a vinyl content of 0.04 mmole / gm, purchased from Shanghai Jiushi Chemical Co., Ltd., with a product number of 671; the hydrogen content of the hydrogen-containing silicone oil is 8.6 mmole / gm, purchased from Anbiya Special Silicone (Nantong) Co., Ltd., with a product number of Andisil XL1342; dispersant AG-151 purchased from Zhongtai Lianhua New Materials; the brand of fumed silica is Evonik Degussa R972; the brand of platinum catalyst is Shin-Etsu CAT-PL-56; γ-aminopropyltriethoxysilane is the silane coupling agent, the brand is Dow Corning KH-550, 3,7,11-trimethyldodecyne-3-ol (TMDO for short) is the inhibitor, purchased from Forssman Company (Beijing), the product number is 9401003.

[0057] The above-mentioned 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 Materials Technology Co., Ltd.; the particle size of aluminum nitride is about 40-60 μm, purchased from Shanghai Yaotian New Materials Technology Co., Ltd.

[0058] The preparation method of the above-mentioned organic silicon thermal conductive coating comprises the following steps: S1. Weigh the first vinyl silicone resin, the second vinyl silicone resin, the hydrogenated silicone oil, 3,7,11-trimethyldodecyl-3-ol, γ-aminopropyltriethoxysilane and the dispersant according to the above weight ratios, mix them, and stir them at a stirring speed of 600-800 r / min for 5-10 min to form a uniform colloid, i.e., the first mixture; S2. According to the above weight proportions, fumed silica, carbon nanotubes, boron nitride and aluminum nitride are weighed, added to the above first mixture, dispersed at a stirring speed of 1500-2000 r / min for 20 min, and then ultrasonically treated at 750 W for 25 min to fully mix, to obtain a second mixture; S3, adding platinum catalyst to the second mixture, mixing evenly, and obtaining the organosilicon coating after reaction.

[0059] Comparative Example 1: This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between the silicone thermal conductive coating and Example 1 is that the addition ratio of the first vinyl silicone resin to the second vinyl silicone resin is adjusted, and the other preparation raw materials are the same.

[0060] The raw materials for preparing the organic silicon thermal conductive coating of this comparative example are shown in Table 4 in parts by weight.

[0061] Table 4: Raw materials for preparation of silicone thermal conductive coating in comparative example 1

[0062] The preparation method of the above-mentioned organic silicon thermal conductive coating is referred to the method in Example 1.

[0063] Comparative Example 2: This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between the silicone thermal conductive coating and Example 1 is that the addition ratio of the silane coupling agent γ-aminopropyltriethoxysilane is reduced, and the other preparation raw materials are the same.

[0064] The raw materials for preparing the organic silicon thermal conductive coating of this comparative example are shown in Table 5 in parts by weight.

[0065] Table 5: Raw materials for preparation of silicone thermal conductive coating in comparative example 2

[0066] The preparation method of the above-mentioned organic silicon thermal conductive coating is referred to Example 1.

[0067] Comparative Example 3: This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between the silicone thermal conductive coating and Example 1 is that the addition ratio of carbon nanotubes, boron nitride and aluminum nitride is adjusted to 1:1:6, and the other preparation raw materials are the same.

[0068] The raw materials for preparing the organic silicon thermal conductive coating of this comparative example are shown in Table 6 in parts by weight.

[0069] Table 6: Raw materials for preparation of silicone thermal conductive coating in comparative example 3

[0070] The preparation method of the above-mentioned organic silicon thermal conductive coating is referred to Example 1.

[0071] Comparative Example 4: This comparative example provides an organosilicon thermal conductive coating and a preparation method thereof. The difference between the organosilicon thermal conductive coating and Example 1 is that the addition ratio of the inhibitor (3,7,11-trimethyldodecyne-3-ol) is reduced, and the other preparation raw materials are the same.

[0072] The raw materials for preparing the organic silicon thermal conductive coating of this comparative example are shown in Table 7 in parts by weight.

[0073] Table 7: Raw materials for preparation of silicone thermal conductive coating in comparative example 4

[0074] The preparation method of the above-mentioned organic silicon thermal conductive coating is referred to Example 1.

[0075] Comparative Example 5: This comparative example provides an organosilicon thermal conductive coating and a preparation method thereof. The organosilicon thermal conductive coating is different from Example 1 in that the hydrogen content in the hydrogen-containing silicone oil is reduced, and the other preparation raw materials are the same.

[0076] The raw materials for preparing the organic silicon thermal conductive coating of this comparative example are shown in Table 8 in parts by weight.

[0077] Table 8: Raw materials for preparation of silicone thermal conductive coating in comparative example 5

[0078] The hydrogen content in the hydrogen-containing silicone oil is about 0.5-0.8%Wt, and the converted molar concentration is about 4.95-7.94mmole / gm.

[0079] The preparation method of the above-mentioned organic silicon thermal conductive coating is prepared with reference to Example 1.

[0080] Comparative Example 6: This comparative example provides an organosilicon thermal conductive coating and a preparation method thereof. The organosilicon thermal conductive coating is different from Example 1 in that the hydrogen content in the hydrogen-containing silicone oil is increased, and the other preparation raw materials are the same.

[0081] The raw materials for preparing the organic silicon thermal conductive coating of this comparative example are shown in Table 9 in parts by weight.

[0082] Table 9: Raw materials for preparation of silicone thermal conductive coating in comparative example 6

[0083] Among them, the hydrogen content in the hydrogen-containing silicone oil is about 1.4-1.6%Wt, and the converted molar concentration is about 13.88-15.85mmole / gm.

[0084] The preparation method of the above-mentioned organic silicon thermal conductive coating is prepared with reference to Example 1.

[0085] Comparative Example 7: This comparative example provides an organosilicon thermal conductive coating and a preparation method thereof. The organosilicon thermal conductive coating is different from Example 1 in that the fumed silica is replaced with conventional silica powder, and the other preparation raw materials are the same.

[0086] The raw materials for preparing the silicone thermal conductive coating of this comparative example are shown in Table 10 in parts by weight.

[0087] Table 10: Raw materials for preparation of silicone thermal conductive coating in comparative example 7

[0088] The average particle size of silicon dioxide is 3.4-4.0 μm and it was purchased from Grace Company with the product number C803.

[0089] The preparation method of the above-mentioned organic silicon thermal conductive coating is referred to Example 1.

[0090] Comparative Example 8: This comparative example provides a silicone thermal conductive coating and a preparation method thereof. The difference between the silicone thermal conductive coating and Example 1 is that the second vinyl siloxane resin is replaced with a siloxane resin with a viscosity of 65000cps / 25°C, and the other preparation raw materials are the same.

[0091] The raw materials for preparing the silicone thermal conductive coating of this comparative example are shown in Table 11 in parts by weight.

[0092] Table 11: Raw materials for preparation of silicone thermal conductive coating in comparative example 8

[0093] The second vinyl siloxane resin has a viscosity of 65,000 cps at 25° C. and a vinyl content of 0.03 mmole / gm. It was purchased from Anbiya Special Silicone (Nantong) Co., Ltd. with the brand name Andisil® VS 65000.

[0094] The preparation method of the above-mentioned organic silicon thermal conductive coating is referred to Example 1.

[0095] Comparative Example 9: This comparative example provides an organosilicon thermal conductive coating and a preparation method thereof. The organosilicon thermal conductive coating is different from Example 1 in that the carbon nanotubes are replaced with an equal amount of boron nitride (ie, no carbon nanotubes are added), and the other preparation raw materials are the same.

[0096] The raw materials for preparing the silicone thermal conductive coating of this comparative example are shown in Table 12 in parts by weight.

[0097] Table 12: Raw materials for preparation of silicone thermal conductive coating in comparative example 9

[0098] The preparation method of the above-mentioned organic silicon thermal conductive coating is referred to Example 1.

[0099] Test example 1: In this test example, the thermal conductivity of the organic silicon thermal conductive coatings prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-9 is tested, and the test method specifically refers to the ASTM D 5470 test standard.

[0100] The test results are shown in Table 13.

[0101] Table 13: Thermal conductivity test results

[0102] The above results show that the thermal conductive coating prepared by the organic silicon thermal conductive coating of the present invention exhibits excellent thermal conductivity, and its thermal conductivity coefficient is greater than 12W / (m·K). Using it in a power battery module can quickly disperse heat, thereby ensuring the performance and safety of the battery.

[0103] Furthermore, when the raw material components were adjusted (such as Comparative Examples 1-9), the thermal conductivity coefficient decreased to varying degrees. Among them, when the addition ratio of carbon nanotubes, boron nitride and aluminum nitride in the coating system was adjusted to 1:1:6 (such as Comparative Example 3), the thermal conductivity coefficient decreased significantly to only 10.5 W / (m·K). It is speculated that this is because as the addition ratio of aluminum nitride (particle size 40-60 μm) increases, the large-particle-size thermal conductive filler dominates the entire filler system, and it is difficult for the thermal conductive fillers to form a dense stack, which is not conducive to the formation of a thermal conductive path.

[0104] In addition, it is worth noting that when the viscosity of the siloxane resin in the system is too high (such as in Comparative Example 1) and the hydrogen content in the hydrogen-containing silicone oil is too high (such as in Comparative Example 6), it is also not conducive to the improvement of the thermal conductivity. It is speculated that the thermal conductivity of the coating mainly depends on the arrangement and filling density of the components (such as siloxane resin, thermal conductive filler and other additives) in the thermal conductive coating. If the viscosity of the siloxane resin is too high, it may cause the filler in the coating to be unevenly dispersed or produce larger particle gaps. These microstructural inhomogeneities will hinder the heat conduction path and thus reduce the thermal conductivity. When the hydrogen content in the hydrogen-containing silicone oil is too high, since hydrogen atoms are low-quality thermal conductors, the thermal expansion coefficient of the material may increase, especially in a high-temperature environment. The increase in the thermal expansion coefficient will increase the instability of the coating, thereby destroying the continuity of heat conduction.

[0105] Test example 2: In this test example, the silicone thermal conductive coatings prepared in the above-mentioned embodiments 1-3 and comparative examples 1-9 were subjected to adhesion test, water boiling test and aging test, and their ease of construction was evaluated, wherein: (1) Adhesion test: According to GB9286-2021 standard. Level 0 means that the cutting edge is completely smooth and there is no shedding in the grid; Level 1 means that there is a little coating shedding at the intersection of the cuts, but the affected cross-cut area is no more than 5%; Level 2 means that there is coating shedding at the intersection of the cuts and / or along the edges of the cuts, and the affected cross-cut area is greater than 5% but not more than 15%.

[0106] (2) Boiling test: Apply the coating on a metal sheet, dry it at 60°C for 60 min, then soak the prepared coating in boiling water (about 100°C) for 120 min and observe the surface condition of the coating.

[0107] (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.

[0108] (4) Construction performance evaluation: Evaluation is conducted based on the difficulty of coating.

[0109] The test results are shown in Table 14.

[0110] Table 14: Related performance test results

[0111] The above results show that the organic silicon thermal conductive coating prepared by the formula of the present invention has excellent adhesion, water boiling resistance and anti-aging properties, and has moderate viscosity and is easy to construct. 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 anti-aging properties are slightly reduced, which is presumably related to the oxidation of carbon nanotubes. Under the illumination of xenon lamps, the surface temperature of the coating increases, which promotes the reaction of oxygen with the surface of carbon nanotubes, affecting the anti-aging performance.

[0112] Compared with Example 1, Comparative Example 1 increases the relative content of the second vinyl siloxane resin, and Comparative Example 8 further increases the viscosity of the second vinyl siloxane resin to 65,000 cps / 25°C. The results show that the fluidity of the coating during the coating process deteriorates, resulting in construction difficulties. At the same time, it is worth noting that the coating prepared using the coating of Comparative Example 8 partially fell off or peeled off during the water boiling test. It is speculated that this is because the siloxane resin itself has a certain hydrophilicity, and when the viscosity of the siloxane resin increases, it is easy to cause the coating to absorb moisture, thereby affecting its adhesion stability.

[0113] Compared with Example 1, Comparative Example 2 reduces the addition ratio of γ-aminopropyltriethoxysilane to thermally conductive fillers (carbon nanotubes, boron nitride and aluminum nitride) from the original 1:80 to 1:160. The test results show that the adhesion, boiling resistance and anti-aging properties of the thermal conductive coating are significantly reduced. It is speculated that the reduction of γ-aminopropyltriethoxysilane leads to uneven dispersion of the thermally conductive filler in the silicone material, which ultimately causes its various properties to decline to varying degrees.

[0114] Compared with Example 1, Comparative Example 3 adjusts the addition ratio of carbon nanotubes, boron nitride and aluminum nitride to 1:1:6, and Comparative Example 9 replaces carbon nanotubes with an equal amount of boron nitride. The results show that the adhesion, boiling resistance and anti-aging performance of Comparative Example 3 do not change significantly, but the anti-aging performance of Comparative Example 9 decreases. It is speculated that the network structure of the coating is unstable due to the lack of carbon nanotubes, which in turn affects the anti-aging performance. It can be seen that adding a certain proportion of carbon nanotubes to the thermal conductive coating system of the present invention can also help improve the structural stability and thus improve the anti-aging performance.

[0115] Compared with Example 1, Comparative Example 4 reduces the amount of inhibitor added, and the results show that the construction life is shortened. Comparative Example 5 reduces the hydrogen content in the hydrogen-containing silicone oil, while Comparative Example 6 increases the hydrogen content in the hydrogen-containing silicone oil. The results show that the adhesion, water boiling resistance and anti-aging properties of the thermal conductive coating prepared therefrom are significantly deteriorated. It is speculated that the lower hydrogen content leads to a lower efficiency of the silicon-hydrogen addition reaction, which affects the degree of crosslinking between the siloxane 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 leading to poor performance; when the hydrogen content is high, due to excessive crosslinking or uneven crosslinking structure, a relatively dense crosslinking structure may be formed on the surface of the thermal conductive coating, causing the coating to become brittle and hard, lacking sufficient flexibility and ductility, and ultimately reducing the interaction force between the coating and the substrate, resulting in reduced adhesion.

[0116] Compared with Example 1, in Comparative Example 7, the fumed silica was replaced with conventional silica powder. The results showed that the construction difficulty of the coating increased and the aging resistance also decreased. It is speculated that this is because the conventional silica powder particles are larger and the dispersibility is relatively poor, which leads to increased viscosity of the coating, poor fluidity, and more difficult uniform coating during construction; and the decrease in aging resistance is speculated to be related to its uneven distribution.

[0117] The above results show that the silicone thermal conductive coating prepared by the formula of the present invention has excellent adhesion, water boiling resistance and anti-aging properties, and is easy to construct. However, after replacing, adjusting and omitting the proportion of its components, its corresponding performance has declined to varying degrees, which is not conducive to the improvement of its comprehensive performance.

[0118] In summary, the present invention provides a silicone thermal conductive coating and a preparation method and application thereof. The present invention solves the problems of difficult construction of thermal conductive coatings and too low thermal conductivity by matching thermal conductive fillers with components such as siloxane resin in the silicone thermal conductive coating. The coating prepared by the silicone thermal conductive coating of the present invention not only has excellent thermal conductivity, with a thermal conductivity of more than 12W / (m·K), but also has excellent adhesion, boiling resistance and anti-aging properties, and is easy to construct. Using it in a power battery module can achieve rapid heat dissipation, thereby ensuring the performance and safety of the battery, and has broad application prospects.

[0119] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. 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: According to weight parts, the preparation raw materials include: 6-10 parts of the first vinyl siloxane resin, 2-6 parts of the second vinyl siloxane resin, 1-3 parts of hydrogenated 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, and 30-50 parts of aluminum nitride; 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; and the hydrogen content of the hydrogen-containing silicone oil is 8-12 mmol / g.

2. The organic silicon thermal conductive coating according to claim 1, characterized in that: The carbon nanotubes have a diameter of 1-20 nm and a length of 10-30 μm; And / or, the particle size of the boron nitride is 50-100 nm; And / or, the particle size of the aluminum nitride is 40-60 μm.

3. The organic silicon thermal conductive coating according to claim 1, characterized in that: The carbon nanotubes are selected from single-walled carbon nanotubes and multi-walled carbon nanotubes or a combination thereof.

4. The organic silicon thermal conductive coating according to claim 3, characterized in that: The weight ratio of the carbon nanotubes, the boron nitride and the aluminum nitride is 1:1-2:2-4.

5. The organic silicon thermal conductive coating according to claim 1, characterized in that: The first vinyl siloxane resin is a methyl vinyl siloxane resin; And / or, the second vinyl silicone resin is a modified methyl vinyl silicone resin, wherein the active groups of the modified methyl vinyl silicone resin include one or more of hydroxyl groups and epoxy groups.

6. The organic silicon thermal conductive coating according to any one of claims 1 to 5, characterized in that: The preparation raw materials also contain 0.1-0.5 parts of a dispersant and 0.2-0.4 parts of an acetylene alcohol inhibitor.

7. The organic silicon thermal conductive coating according to claim 6, characterized in that: The acetylene alcohol inhibitor includes 3,7,11-trimethyldodecyn-3-ol.

8. A method for preparing the organic silicon thermal conductive coating according to any one of claims 1 to 7, characterized in that: The method comprises mixing the preparation raw materials to obtain the product.

9. A silicone thermal conductive coating, characterized in that: The thermally conductive silicone coating is prepared by curing the thermally conductive silicone coating according to any one of claims 1 to 7.

10. Use of the organic silicon thermal conductive coating according to any one of claims 1 to 7 in the preparation of thermal conductive materials.

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