Environment-friendly graphene heat dissipation coating and preparation method thereof

Abstract

The invention is suitable for the technical field of coatings, and provides an environment-friendly graphene heat dissipation coating and a preparation method thereof.The preparation method comprises the following steps that a catalyst is added into glycidyl methacrylate and a silane coupling agent for a ring-opening-polymerization reaction, and a modified silane coupling agent is obtained; gallic acid or a derivative thereof is added into the modified silane coupling agent for continuous reaction, and a coating matrix is obtained; adding graphene into the coating matrix, and carrying out ultrasonic homogenization; and uniformly mixing the cured resin with the coating matrix to obtain the graphene heat dissipation coating. By introducing gallic acid and a derivative thereof as a polyphenol cross-linking agent and adopting a modified silane coupling agent and the like, the problems that graphene is easy to agglomerate and difficult to disperse in a system are solved, covalent bonding between graphene and an organic resin matrix is realized, the interface thermal resistance is effectively reduced, the phonon transmission efficiency is improved, and the graphene / organic resin composite material has a good application prospect. And high thermal conductivity and strong thermal radiation capability are achieved.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and in particular relates to an environmentally friendly graphene heat dissipation coating and its preparation method. Background Technology

[0002] With the rapid development of the electronics industry, modern electronic devices are increasingly becoming highly integrated systems assembled at high density. This leads to a significant increase in the heat flux density of these products. If the heat dissipation capacity is insufficient, the temperature of components and circuits will rise, causing thermal deformation and failure, thus affecting the performance and lifespan of electronic products. Furthermore, in industries such as metallurgy, petrochemicals, ceramics, and pharmaceuticals, various industrial boilers, power plant boilers, and furnaces are often involved, and their heat dissipation performance is crucial to personnel safety and the reliable operation of equipment. Therefore, improving the heat dissipation performance of equipment in the electronics industry and other fields has become an important issue for promoting industrial progress.

[0003] Heat dissipation coatings are special coatings that enhance the heat dissipation performance of objects by improving the surface radiation efficiency (especially infrared radiation efficiency). They have advantages such as low cost and simple implementation.

[0004] Graphene has a very high thermal conductivity and extremely high emissivity. The thermal conductivity of a single layer of graphene can reach 5300 W / m·K, and its thermal emissivity in the infrared range is 0.99. Therefore, graphene has great potential as a heat dissipation material.

[0005] However, the application of graphene in coatings currently faces many challenges: graphene is prone to agglomeration and difficult to disperse in solvents; low graphene content in solvents hinders the utilization of its excellent heat dissipation properties. Existing technologies disperse graphene in solvents by adding dispersants, but this often results in very low graphene content, a high proportion of additives, or a low overall graphene content in the coating. Low graphene content makes industrialization difficult or unfavorable, while a high proportion of dispersants makes it difficult to leverage the inherent advantages of graphene. For example, CN108250890A discloses a graphene content of only 5-7 parts; CN108394892A discloses a graphene slurry with a content of only 1-5 mg / L and a high amount of additives; and CN108276867A discloses a graphene heat dissipation coating with a high resin content, and the coating formation process is not conducive to the formation of finer graphene particles, while graphene agglomeration hinders heat dissipation. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing an environmentally friendly graphene heat dissipation coating, thereby addressing the problems mentioned in the background section.

[0007] The present invention is implemented as follows: a method for preparing an environmentally friendly graphene heat dissipation coating includes the following steps:

[0008] 1) A modified silane coupling agent is obtained by adding a catalyst to glycidyl methacrylate and a silane coupling agent to carry out a ring-opening polymerization reaction, wherein the mass ratio of glycidyl methacrylate to silane coupling agent is 1:10~5:1;

[0009] 2) Add gallic acid or its derivative to the modified silane coupling agent and continue the reaction to obtain a coating matrix, wherein the mass ratio of the modified silane coupling agent to gallic acid or its derivative is 1:1 to 10:1;

[0010] 3) Add graphene to the coating matrix and perform ultrasonic homogenization to ensure uniform dispersion of graphene in the coating matrix. The amount of graphene added is 3% to 12% of the mass of the coating matrix.

[0011] 4) After the curing resin and the coating matrix are mixed evenly, a graphene heat dissipation coating is obtained. The amount of curing resin added is 5% to 20% of the total mass of the curing resin and the coating matrix.

[0012] Another objective of this invention is to provide an environmentally friendly graphene heat dissipation coating, which is prepared using the above-described preparation method.

[0013] The preparation method provided in this invention has the following advantages compared with the prior art:

[0014] 1. The raw materials are both environmentally friendly and high-performing, and the production process is more environmentally friendly, which is in line with the development trend of green products;

[0015] 2. The preparation process is simple, and by introducing gallic acid and its derivatives as polyphenol crosslinking agents and using modified silane coupling agents, the problems of easy aggregation and difficult dispersion of graphene in the system are effectively solved. This stable dispersion system, combined with ultrasonic-assisted homogenization dispersion technology, provides convenience for subsequent industrial and large-scale production.

[0016] 3. By using the bifunctional groups of silane coupling agents to achieve covalent bonding between graphene and organic resin matrix, the interfacial thermal resistance is effectively reduced and the phonon transmission efficiency is improved. The resulting coating has both high thermal conductivity and strong thermal radiation capability, making it highly practical in the field of thermal management such as electronic components, LED modules and new energy battery thermal management.

[0017] 4. While ensuring excellent heat dissipation performance, the efficient utilization of graphene is achieved. Through a strategy that combines chemical bonding and physical dispersion, superior heat dissipation effect can be achieved with a relatively low amount of graphene added (5%-8%), reducing the raw material cost of high-performance heat dissipation coatings. Attached Figure Description

[0018] Figure 1The result is the normalized infrared emissivity data of the graphene heat dissipation coating prepared in Example 1 of this invention.

[0019] Figure 2 The results of the test on LED lamps are as follows: The graphene heat dissipation coating prepared in Example 1 of this invention is shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0022] Example 1: An environmentally friendly graphene heat dissipation coating, the preparation method of which includes the following steps:

[0023] (1) Weigh 20 g glycidyl methacrylate and 10 g 3-aminopropyltriethoxysilane, add 0.15 g p-toluenesulfonic acid as catalyst, and react at 110℃ for 4.5 hours to obtain a modified silane coupling agent.

[0024] (2) Take 21 g of the above modified product, add 7 g of gallic acid, heat to 120°C, react for 180 minutes to form a coating matrix;

[0025] (3) Add 5% graphene by mass to the coating matrix, disperse it under 500 W ultrasonic power for 120 minutes, and then homogenize it under 80 MPa pressure for 40 minutes;

[0026] (4) Add 5 g of water-based acrylic resin, stir evenly, and obtain heat dissipation coating.

[0027] Example 2: An environmentally friendly graphene heat dissipation coating, the preparation method of which includes the following steps:

[0028] (1) Weigh 20 g glycidyl methacrylate and 50 g γ-methacryloxypropyltrimethoxysilane, add 0.6 g methanesulfonic acid as catalyst, and react at 140℃ for 3 hours to obtain a modified silane coupling agent.

[0029] (2) Take 30 g of the above modified product, add 6 g of pyrogallol, heat to 160℃, react for 150 minutes to form a coating matrix;

[0030] (3) Add 5.5% graphene by mass to the coating matrix, disperse it under 2000 W ultrasonic power for 60 minutes, and then homogenize it under 100 MPa pressure for 20 minutes;

[0031] (4) Add 5.1 g of water-based silicone-modified acrylic resin, stir evenly, and obtain a heat dissipation coating.

[0032] Example 3: An environmentally friendly graphene heat dissipation coating, the preparation method of which includes the following steps:

[0033] (1) Weigh 40 g glycidyl methacrylate and 40 g vinyltriethoxysilane, add 2.4 g tungstic acid catalyst, and react at 90°C for 5 hours to obtain modified silane coupling agent;

[0034] (2) Take 48 g of the above modified product, add 8 g of methyl gallate, heat to 80°C, react for 200 minutes to form a coating matrix;

[0035] (3) Add 8% graphene by mass to the coating matrix, disperse it under 80 W ultrasonic power for 180 minutes, and then homogenize it under 85 MPa pressure for 60 minutes;

[0036] (4) Add 6.8 g of melamine resin, stir evenly, and obtain heat dissipation coating.

[0037] Example 4: An environmentally friendly graphene heat dissipation coating, the preparation method of which includes the following steps:

[0038] (1) Weigh 25 g of glycidyl methacrylate and 62.5 g of 3-aminopropyltriethoxysilane, add 0.375 g of p-toluenesulfonic acid as catalyst, and react at 130°C for 3.5 hours to obtain a modified silane coupling agent.

[0039] (2) Take 52.5 g of the above modified product, add 7.5 g of gallic acid, heat to 140℃, react for 120 minutes to form a coating matrix;

[0040] (3) Add 6.5% graphene by mass to the coating matrix, disperse it under 1000 W ultrasonic power for 100 minutes, and then homogenize it under 90 MPa pressure for 50 minutes;

[0041] (4) Add 12 g of vinyl resin, stir evenly, and obtain the heat dissipation coating.

[0042] Example 5: An environmentally friendly graphene heat dissipation coating, the preparation method of which includes the following steps:

[0043] (1) Weigh 20 g glycidyl methacrylate, 10 g 3-aminopropyltriethoxysilane and 10 g γ-(2,3-epoxypropoxy)propyltrimethoxysilane, add 0.8 g phosphotungstic acid catalyst, and react at 100℃ for 4 hours to obtain modified silane coupling agent.

[0044] (2) Take 15 g of the above modified product, add 3.75 g of gallic acid lauryl ester, heat to 95°C, react for 210 minutes to form a coating matrix;

[0045] (3) Add 7% graphene by mass to the coating matrix, disperse it under 800 W ultrasonic power for 70 minutes, and then homogenize it under 70 MPa pressure for 45 minutes;

[0046] (4) Add 2.5 g of water-based acrylic resin and 2.5 g of amino resin, stir evenly, and obtain heat dissipation coating.

[0047] Example 6: An environmentally friendly graphene heat dissipation coating, the preparation method of which includes the following steps:

[0048] (1) Weigh 30 g glycidyl methacrylate and 15 g γ-(2,3-epoxypropoxy)propyltrimethoxysilane, add 0.675 g phosphomolybdic acid as catalyst, and react at 85°C for 5 hours to obtain a modified silane coupling agent.

[0049] (2) Take 36 g of the above modified product, add 9 g of propyl gallate, heat to 110℃, react for 200 minutes to form a coating matrix;

[0050] (3) Add 7% graphene by mass to the coating matrix, disperse it under 1200 W ultrasonic power for 80 minutes, and then homogenize it under 75 MPa pressure for 35 minutes;

[0051] (4) Add 8 g of amino resin, stir evenly, and the heat dissipation coating is obtained.

[0052] Comparative Example 1 differs from Example 1 only in that gallic acid and its derivatives are not added.

[0053] Comparative Example 2 differs from Example 1 only in that the ultrasonic and high-pressure homogenization dispersion of graphene is omitted.

[0054] Comparative Example 3 differs from Example 1 only in that the modification process of the silane coupling agent is omitted.

[0055] Comparative Example 4

[0056] Suzhou **Graphene Technology Co., Ltd., Thermal Coating Model TF-18621

[0057] Comparative Example 5

[0058] Guangdong ** Technology Co., Ltd., thermal coating model MR-TC.

[0059] Performance testing and comparison:

[0060] Examples 1-6 and Comparative Examples 1-5 were all cured at 120°C for 10 min, and the performance data are shown in Table 1:

[0061] Table 1

[0062] Case thermal conductivity Infrared emissivity Adhesion Environmental protection Salt spray resistance Example 1 10.2 0.95 Level I ≤20 g / L 300 h Example 2 8.6 0.92 Level I ≤20 g / L 270 h Example 3 7.8 0.86 Level I ≤20 g / L 240 h Example 4 8.5 0.89 Level I ≤20 g / L 264 h Example 5 8.9 0.85 Level I ≤20 g / L 288 h Example 6 9.0 0.87 Level I ≤20 g / L 280 h Comparative Example 1 5.1 0.8 Easy to fall off ≤20 g / L ≤24 h Comparative Example 2 1.5 0.64 Easy to fall off ≤20 g / L ≤24 h Comparative Example 3 2.1 0.68 Very easy to fall off ≤20 g / L Comparative Example 4 5~10 ≥0.85 Level I ≤200 g / L ≤120 h Comparative Example 5 5~10 ≥0.85 Level I ≤300 g / L ≤96 h

[0063] As can be seen, all embodiments of the present invention exhibit high thermal conductivity (7.8-10.2), high infrared emissivity (0.85-0.95), excellent Class I adhesion, good environmental performance (VOCs ≤20 g / L), and excellent salt spray resistance (240-300 hours). Among them, Embodiment 1 has the best overall performance.

[0064] The thermal conductivity (5.1) and adhesion (easy to fall off) of Comparative Example 1 (gallic acid omitted) decreased significantly, and the salt spray resistance time dropped sharply to less than 24 hours, proving that gallic acid is indispensable as a polyphenol crosslinking agent for constructing a stable coating structure and improving performance.

[0065] Comparative Example 2 (omitted ultrasonic homogenization) has extremely low thermal conductivity (1.5) and infrared emissivity (0.64), and its performance is severely degraded, highlighting the decisive role of ultrasonic-assisted homogenization dispersion technology in achieving uniform dispersion of graphene and maximizing its heat dissipation potential.

[0066] Comparative Example 3 (with the coupling agent modification process omitted) has low thermal conductivity (2.1) and infrared emissivity (0.68), resulting in deteriorated performance and lack of adhesion conditions. Silane coupling agent modification has a significant impact on the adhesion ability of graphene heat dissipation coatings.

[0067] Compared with the commercially available samples of Comparative Examples 4 and 5, the embodiments of the present invention, while ensuring high thermal conductivity and high emissivity, clearly achieve better environmental protection standards (VOCs≤20 g / L) and significantly longer salt spray resistance time (far exceeding 120 / 96 hours), demonstrating its comprehensive advantages in environmental protection and durability.

[0068] The graphene heat dissipation coating prepared in Example 1 was cured and then subjected to infrared emissivity testing. The normalized data is shown in the figure below. Figure 1As shown, the graphene heat dissipation coating has the most concentrated infrared emissivity in the wavelength range of 8~14 μm, which is consistent with the main wavelength of electronic device radiation and has a high degree of matching with the thermal balance of the environment, thus achieving "precise radiation heat dissipation".

[0069] The graphene heat dissipation coating prepared in Example 1 was applied to an LED lamp, and its actual heat dissipation effect was tested. The results are as follows: Figure 2 As shown, at the same time, the temperature of the lamp surface of the equipment coated with graphene heat dissipation coating can be reduced by up to 38%, the temperature of the vent can be increased by up to 47%, and the temperature of the controller can be reduced by up to 35%. The equipment without graphene heat dissipation coating will automatically stop working after 130 minutes due to excessive operating temperature. The equipment coated with graphene heat dissipation coating will not stop working after 300 minutes of operation.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an environmentally friendly graphene heat dissipation coating, characterized in that, Includes the following steps: 1) A modified silane coupling agent is obtained by adding a catalyst to glycidyl methacrylate and a silane coupling agent to carry out a ring-opening polymerization reaction, wherein the mass ratio of glycidyl methacrylate to silane coupling agent is 1:3~2:1; 2) Add gallic acid or its derivative to the modified silane coupling agent and continue the reaction to obtain a coating matrix, wherein the mass ratio of the modified silane coupling agent to gallic acid or its derivative is 3:1 to 7:1; 3) Add graphene to the coating matrix and perform ultrasonic homogenization to ensure uniform dispersion of graphene in the coating matrix. The amount of graphene added is 5% to 8% of the mass of the coating matrix. 4) After the curing resin and the coating matrix are mixed evenly, a graphene heat dissipation coating is obtained. The amount of curing resin added is 5% to 20% of the total mass of the curing resin and the coating matrix.

2. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 1), the silane coupling agent is one or more of 3-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and vinyltriethoxysilane.

3. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 1), the catalyst is one or more of p-toluenesulfonic acid, methanesulfonic acid, tungstic acid, phosphomolybdic acid, and phosphotungstic acid, and the amount of catalyst added is 5‰ to 3% of the total mass of glycidyl methacrylate and silane coupling agent.

4. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 1), the reaction temperature of the ring-opening polymerization reaction is 50~180℃, and the reaction time is 2~10 h.

5. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 2), the gallic acid or its derivative is one or more of gallic acid, pyrogallic acid, lauryl gallate, methyl gallate, and propyl gallate.

6. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 2), the reaction temperature is 50~180℃ and the reaction time is 30~300 min.

7. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 3), the number of graphene layers is 1 to 10, and the specific surface area is 100 to 800 m². 2 / g, with a radial dimension of 0.5–5 μm.

8. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 3), the ultrasonic power of the ultrasonic homogenization is 30~3000 W, the ultrasonic time is 30~300 min, the homogenization pressure is 40~120 MPa, and the homogenization time is 10~60 min.

9. The preparation method of the environmentally friendly graphene heat dissipation coating according to claim 1, characterized in that, In step 4), the cured resin is one or more of the following: waterborne acrylic resin, waterborne silicone-modified acrylic resin, amino resin, vinyl resin, and melamine resin.

10. An environmentally friendly graphene heat dissipation coating, characterized in that, It is prepared using the preparation method described in any one of claims 1-9.

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