A heat-conducting insulating paint and a method for preparing the same

Abstract

This invention discloses a method for preparing a thermally conductive and insulating coating, comprising the following steps: taking a base resin, adding an active diluent, reducing the viscosity of the base resin and mixing it evenly under heating and stirring conditions, and then stopping the heating; sequentially adding modified hexagonal boron nitride nanosheets and nano-Al 2 O 3 The thermally conductive and insulating coating is prepared by dispersing coupling agent, leveling agent, initiator, stabilizer, curing agent, and defoamer for several hours. The modified hexagonal boron nitride nanosheets are hexagonal boron nitride nanosheets modified with amino acids. The thermally conductive and insulating coating prepared by the method provided by this invention has good thermal conductivity and good insulation properties on circuit boards, exceeding 25kV / mm. The entire production process is pollution-free, non-toxic, and more environmentally friendly, and the entire process is relatively simple.

Description

A thermally conductive and insulating coating and its preparation method Technical Field

[0001] This invention relates to the field of industrial coatings technology, and in particular to a thermally conductive and insulating coating and its preparation method. Background Technology

[0002] With the continuous development of the electronics industry, electronic devices are becoming increasingly miniaturized and highly integrated, with higher and higher device density per unit volume. While performance is improved, the heat generated inside the devices is also increasing dramatically. If the heat is not dissipated, it will seriously affect the lifespan of the electronic devices.

[0003] Currently used thermally conductive and insulating coatings typically improve thermal conductivity by adding large amounts of metals or metal oxides to thermally conductive polymers. These inorganic fillers have relatively poor dispersion and high density in the coating. Graphene has been extensively studied in thermally conductive and heat-dissipating coatings in recent years; however, its high electrical conductivity limits its application in some fields. Hexagonal boron nitride (BON) has a highly similar structure to graphene, and its properties are essentially the same except for conductivity. BON is plate-like; in a thermally conductive network, heat is transferred via phonons, and the gaps between these plates affect heat transfer. Adding particulate thermally conductive fillers can significantly improve thermal conductivity. Therefore, this study develops a coating using modified hexagonal boron nitride as the thermally conductive filler, aiming to maintain good insulation while ensuring high thermal conductivity. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a thermally conductive and insulating coating and its preparation method, which is to modify hexagonal boron nitride to prepare the thermally conductive and insulating coating.

[0005] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a method for preparing a thermally conductive and insulating coating, comprising the following steps:

[0006] Step 1: Take the base resin, add the reactive diluent, and reduce the viscosity of the base resin under heating and stirring conditions until it is mixed evenly, then stop heating;

[0007] Step 2: Add modified hexagonal boron nitride nanosheets, nano Al2O3, coupling agent, leveling agent, initiator, stabilizer, curing agent, and defoamer in sequence, and disperse for several hours to obtain a thermally conductive and insulating coating;

[0008] The modified hexagonal boron nitride nanosheets are hexagonal boron nitride nanosheets modified with amino acids.

[0009] In a preferred embodiment of the present invention, the method for preparing the modified hexagonal boron nitride nanosheets includes the following steps:

[0010] (1) Take hexagonal boron nitride in concentrated NaOH solution and then grind it by ball mill for 24-32 hours to obtain hydroxylated hexagonal boron nitride nanosheets. Remove the bottom residue, centrifuge the upper liquid, and wash it with anhydrous ethanol until neutral and dry it.

[0011] (2) Take 3-20g of amino acids in 200mL of concentrated sulfuric acid, add 20-60g of hydroxylated hexagonal boron nitride nanosheets obtained in step (1), react under heating conditions for 0.5-1.5h, filter and dry to obtain modified hexagonal boron nitride nanosheets.

[0012] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide a thermally conductive and insulating coating prepared by the preparation method of the thermally conductive and insulating coating as described above.

[0013] In a preferred embodiment of the present invention, the thermally conductive and insulating coating is composed of the following components in parts by weight: 40-60g of matrix resin, 10-25g of reactive diluent, 20-30g of modified hexagonal boron nitride nanosheets, 10-15g of nano Al2O3, 0.5-2g of coupling agent, 1-2g of leveling agent, 0.5-2g of initiator, 0.5-1.5g of stabilizer, 10-20g of curing agent, and 0.5-1.5g of defoamer.

[0014] The following is information on the raw materials used in the implementation plan:

[0015] Boron nitride: H-BN-F produced by Shenzhen Hongyuan Chemical New Material Technology Co., Ltd., with a particle size ≥27μm; Boron nitride TW produced by Shandong Jingyi New Material Co., Ltd., with a particle size of 2~10μm; the two are mixed in a 1:1 ratio;

[0016] Nano Al2O3: The nano aluminum oxide LLAl-06 produced by Foshan Shengchuangda Chemical Co., Ltd. has a particle size of 20nm and a specific surface area ≥160m². 2 / g;

[0017] Matrix resin: Bisphenol A type epoxy resin is used: Phoenix brand 6101 and 618 (formerly E44 and E51), of which 6101 has an epoxy equivalent (g / mol) of 210-230 and 618 has an epoxy equivalent (g / mol) of 184-195, with an addition ratio of 1:1 to 3:1.

[0018] Sodium hydroxide, concentrated sulfuric acid, and amino acids: produced by Merck Chemicals;

[0019] Stabilizer: IRGANOX B 900 manufactured by BASF;

[0020] Curing agents: T-31 curing agent produced by Hubei Xinghengye Technology Co., Ltd., and T-188 cationic latent curing agent for epoxy resin produced by Shanghai Huichuang Trading Co., Ltd., with an addition ratio of 1:1;

[0021] Reactive diluent: AGE BLJ-C20, produced by Bailiju, is an reactive diluent for epoxy resin, which reduces the viscosity of epoxy resin;

[0022] Coupling agent: KH-560 produced by Nanjing Xiangqian Chemical Co., Ltd.

[0023] Initiator: Vicbase TC3637 cationic initiator manufactured by Shenzhen Kaiji Applied Materials Co., Ltd., with an initiation temperature of 80℃;

[0024] Defoamer: One or more of BYK-A550, BYK-A530, and BYK-A500 from BYK Chemicals;

[0025] Leveling agent: one or more of BYK-346, BYK-333, and BYK-306 from BYK Chemicals.

[0026] At low temperatures, heat transfer in solid materials primarily occurs through thermal conduction. Modified hexagonal boron nitride (BON) exhibits a plate-like structure with excellent thermal conductivity, acting as a surface conductor; nano-Al₂O₃, being granular, acts as a point conductor, and both are insulators. When modified BON alone transfers heat, the heat transfer rate within the plate-like structure is rapid, but gaps exist between the layers, significantly reducing heat transfer efficiency. Single nano-Al₂O₃ particles have a small contact area, resulting in low heat transfer efficiency, and require high concentrations to achieve any noticeable effect. Adding nano-Al₂O₃ to modified BON fills these gaps, acting as a connector between the BON plates, allowing for rapid heat transfer between them. Compared to adding Al₂O₃ alone, this significantly improves heat transfer efficiency, i.e., enhances thermal conductivity.

[0027] The beneficial effects of this invention are:

[0028] (1) The thermally conductive insulating coating prepared by the method of the present invention has good thermal conductivity and good insulation properties on the circuit board, which is higher than 25kV / mm.

[0029] (2) The entire production process is pollution-free and non-toxic, making it more environmentally friendly, and the whole process is relatively simple. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0031] Example 1:

[0032] Take 40g of base resin and add 10g of reactive diluent. Under heating and stirring conditions, reduce the resin viscosity (temperature 40-50℃, stirring speed 1000 rpm) and mix evenly. Then stop heating and reduce the stirring speed to 300 rpm. Under stirring conditions, slowly add 20g of modified hexagonal boron nitride nanosheets, 10g of nano Al2O3, 0.5g of coupling agent, 1g of leveling agent, 0.5g of initiator, 0.5g of stabilizer, and 10g of curing agent in sequence. Disperse at high speed (2000 rpm) for 1.5h, keeping the temperature below 30℃. Then add 0.5g of defoamer and disperse at 400 rpm for 0.5h to obtain the thermally conductive and insulating coating.

[0033] The modified hexagonal boron nitride nanosheets are prepared as follows: hexagonal boron nitride is placed in concentrated NaOH solution and then ground using a ball mill for 24-32 hours to obtain hydroxylated hexagonal boron nitride nanosheets. The bottom residue is removed, the upper layer is centrifuged, washed with anhydrous ethanol until neutral, and dried. 10g of amino acids are placed in 200mL of concentrated sulfuric acid, and 40g of hydroxylated hexagonal boron nitride nanosheets are added. The mixture is reacted under heating conditions for 1 hour, filtered, and dried to obtain the modified hexagonal boron nitride nanosheets.

[0034] Example 2:

[0035] The difference from Example 1 is that the matrix resin is 60g, the reactive diluent is 20g, and the curing agent is 20g.

[0036] Example 3:

[0037] The difference from Example 1 is that the amount of modified boron nitride added is 30g.

[0038] Example 4:

[0039] The difference from Example 1 is that the amount of nano-alumina added is 15g.

[0040] Comparative Example 1:

[0041] The difference from Example 2 is that the hexagonal boron nitride was not modified and is hexagonal boron nitride powder.

[0042] Comparative Example 2:

[0043] The difference from Example 2 is that hexagonal boron nitride was only modified by hydroxylation and not by amino acid modification.

[0044] Comparative Example 3:

[0045] The difference from Example 1 is that no nano-alumina was added.

[0046] The above embodiments and comparative examples were tested as follows:

[0047] 1. Apply thermally conductive and insulating coating to the heatable circuit board. Take another blank circuit board, connect it to the adapter, and record the surface temperature of the circuit board at different temperatures. The test environment temperature is 20℃. The results are shown in Table 1 below:

[0048] Table 1. Temperature of circuit board surface under different heating temperatures.

[0049] Heating Temperature / °C 50 60 70 80 90 Blank Sample 43.5 54.1 63.4 73.2 83.3 Example 1 35.2 45.4 54.6 63.5 74.4 Example 2 36.1 45.7 56.8 65.1 76.1 Example 3 33.5 43.1 52.8 61.4 71.3 Example 4 34.3 44.7 53.1 62.7 73.9 Comparative Example 1 40.5 50.8 61.2 69.9 81.2 Comparative Example 2 39.5 48.9 58.1 68.7 78.1 Comparative Example 3 41.3 49.8 59.1 69.3 79.8 surface

[0050] In this test, the better the thermal conductivity of the circuit board surface, the lower its surface temperature and the stronger its heat exchange capacity. As can be seen from Table 1, the thermal conductivity of the embodiments is better than that of the comparative examples, and the comparative examples are better than the blank examples. Among the embodiments, Embodiment 3 has the best thermal conductivity, followed by Embodiment 4.

[0051] 2. Place the circuit board prepared above in a constant temperature oven for 1 hour, and record the surface temperature of the circuit board after 1 hour using a multi-channel temperature recorder; the results are shown in Table 2 below:

[0052] Table 2 shows the surface temperature of the circuit board after 1 hour of constant temperature holding.

[0053] Insulation temperature / °C 90 100 110 Blank sample 89.7 99.5 109.5 Example 1 87.5 97.4 106.9 Example 2 86.7 97.3 107.1 Example 3 88.2 98.3 107.5 Example 4 87.9 98.1 107.6 Comparative Example 1 84.1 94.1 104.1 Comparative Example 2 85.1 95.3 104.2 Comparative Example 3 86.4 94.6 104.1 surface

[0054] Under constant temperature conditions, the closer the circuit board surface temperature is to the ambient temperature, the better the thermal conductivity of the circuit board surface. Table 2 shows that the thermal conductivity of the embodiments is better than that of the comparative examples. Similarly, among the embodiments, Embodiment 3 has the best thermal conductivity, followed by Embodiment 4.

[0055] 3. Apply the thermally conductive insulating coating evenly to the surface of the copper foil, let it dry to form a thermally conductive insulating coating, and use a withstand voltage tester to test the breakdown voltage of the thermally conductive insulating coating; the results are shown in Table 3 below:

[0056] Table 3 Pressure Resistance Test

[0057] Sample breakdown voltage (kV / mm): Blank sample 0, Example 1 30.1, Example 2 29.8, Example 3 30.1, Example 4 29.8; Comparative Example 1 30.2, Comparative Example 2 30.1, Comparative Example 3 29.9. surface

[0058] In this test, if the breakdown voltage of the examples differs significantly from that of the comparative examples, it indicates that the modification has damaged the electrical insulation properties of boron nitride. However, comparing the examples in Table 3 with the comparative examples, their breakdown voltages are almost identical, indicating that the modification of boron nitride has not damaged its electrical insulation properties.

[0059] Based on Tables 1-3, it can be concluded that the thermally conductive and insulating coatings containing modified hexagonal boron nitride prepared in Examples 1-4 of the present invention, compared with the comparative examples, have improved thermal conductivity by modifying hexagonal boron nitride, but without losing their insulating properties.

[0060] 4. Apply thermally conductive and insulating coating to the heatable circuit board, then power on the circuit board and heat it to a set temperature of 80℃. Repeat the test for 10 hours on and 2 hours off, with each power-on and power-off cycle constituting one complete test. Record the temperature change on the circuit board surface. The results are shown in Table 4 below.

[0061] Table 4 Temperature changes during repeated tests

[0062] Test count 11050100 Blank sample 73.273.273.273.4 Example 1 63.563.563.663.7 Example 2 65.165.165.265.3 Example 3 61.461.461.561.6 Example 4 62.762.762.862.9 Comparative sample 1 69.97070.572.3 Comparative sample 2 68.768.869.571.9 Comparative sample 3 69.369.470.271.5 surface

[0063] After repeated testing, the closer the surface temperature of the heatable circuit board is to its initial temperature, the smaller the performance degradation and the longer its service life within the range of test cycles. Comparing the examples in Table 4 with Comparative Examples 1 and 2, the examples show less change after the same number of tests, indicating less performance degradation and indirectly reflecting a longer service life.

[0064] 5. Take 35 mL of each of the thermally conductive and insulating coatings prepared according to Examples 1-4 and Comparative Examples 1-3, and place them in 50 mL transparent graduated centrifuge tubes. Store them at 50°C and record the time to 20% sedimentation. The results are shown in Table 5 below:

[0065] Table 5: Settling Time

[0066]

[0067]

[0068] Heating during storage accelerates the settling of the thermally conductive insulating coating; the longer the settling time, the better the dispersion stability. Table 5 shows that the differences between Example 1 and Comparative Examples 1 and 2 indicate that the dispersion stability of hexagonal boron nitride in the system is improved after modification, and that amino acid modification is more effective than simple hydroxyl modification.

[0069] This embodiment is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may use the above content as inspiration to make changes or modifications to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications listed in the above embodiments that do not depart from the technical essence of the claims of the present invention shall still fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a thermally conductive and insulating coating, characterized in that, The following steps are included: Step 1: Take the base resin, add the active diluent, and reduce the viscosity of the base resin under heating and stirring conditions, and mix evenly, and then stop heating; Step 2: Add the modified hexagonal boron nitride nanosheets, nano Al2O3, coupling agent, leveling agent, initiator, stabilizer, curing agent, and defoamer in sequence, and disperse for several hours to obtain the thermally conductive and insulating coating; The modified hexagonal boron nitride nanosheets are hexagonal boron nitride nanosheets modified with amino acids. The preparation method includes the following steps: (1) Take hexagonal boron nitride in concentrated NaOH solution, and then grind it by ball mill for 24~32h to obtain hydroxyl The modified hexagonal boron nitride nanosheets were prepared by removing the bottom residue, centrifuging the upper liquid, washing with anhydrous ethanol until neutral and drying. The hexagonal boron nitride was obtained by mixing H-BN-F with a particle size ≥27μm produced by Shenzhen Hongyuan Chemical New Material Technology Co., Ltd. and TW with a particle size of 2~10μm produced by Shandong Jingyi New Material Co., Ltd. in a 1:1 ratio. (2) Take 3~20g of amino acids in 200mL of concentrated sulfuric acid, add 20~60g of the hydroxylated hexagonal boron nitride nanosheets obtained in step (1), react under heating conditions for 0.5~1.5h, filter and dry to obtain the modified hexagonal boron nitride nanosheets.

2. A thermally conductive and insulating coating prepared by the method described in claim 1.

3. The thermally conductive and insulating coating according to claim 2, characterized in that, It is composed of the following components in parts by weight: 40-60g matrix resin, 10-25g reactive diluent, 20-30g modified hexagonal boron nitride nanosheets, 10-15g nano Al2O3, 0.5-2g coupling agent, 1-2g leveling agent, 0.5-2g initiator, 0.5-1.5g stabilizer, 10-20g curing agent, and 0.5-1.5g defoamer.

4. The thermally conductive and insulating coating according to claim 2, characterized in that, The matrix resin is bisphenol A type epoxy resin.

5. The thermally conductive and insulating coating according to claim 2, characterized in that, The defoamer is one or more of BYK-A550, BYK-A530, and BYK-A500.

6. The thermally conductive and insulating coating according to claim 2, characterized in that, The leveling agent is one or more of BYK-346, BYK-333, and BYK-306.

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