Water-based organic silicon high-temperature-resistant insulating paint and preparation method thereof

Abstract

The invention discloses a water-based organic silicon high-temperature-resistant insulating coating and a preparation method thereof, and belongs to the technical field of insulating coatings. The water-based high-temperature-resistant organic silicon resin is used as a film forming matter, water is used as a solvent, and the low-melting-point fluxing filler with different molten state temperature intervals, the multi-scale insulating filler and the reinforcing filler are added, so that the high temperature resistance and the insulativity of the water-based high-temperature-resistant insulating coating are improved; meanwhile, nanoscale flaky or spherical aluminum oxide is distributed in micron-sized particles such as silica powder and talcum powder, the functional filler in a system and SiO2 ash formed after organic silicon resin is subjected to high temperature are bonded together by the low-melting-point fluxing filler in a molten state, a continuous, complete and compact protective layer is formed on the surface of a base material, and the coating is prevented from cracking. The thickness of the coating prepared by the method is 120 + / -10 microns, the adhesive force is 1-2 grades, the pencil hardness is 2H-3H, and the impact resistance is 40kg. Cm-50kg. Cm.

Description

Technical Field

[0001] The present invention belongs to the technical field of insulating coatings, and more specifically, relates to a water-based organosilicon high-temperature resistant insulating coating and a preparation method thereof. Background Art

[0002] With increasingly stringent environmental regulations and the development of high-temperature industrial equipment, traditional solvent-based insulating coatings are unable to meet demand due to high VOC emissions and insufficient temperature resistance. Especially in the fields of new energy vehicle components, industrial equipment and power equipment, there is an urgent need for insulation protection solutions that are both environmentally friendly and resistant to high temperatures. Currently, the coatings used for high-temperature resistance are mainly inorganic coatings, organic coatings and organic-inorganic coatings, such as inorganic silicate coatings, epoxy coatings and hybrid coatings. Although they are widely used in the protection of high-temperature components such as engines, they face multiple challenges under extreme working conditions: organic coatings and hybrid coatings have high VOC pollution due to their solvent-based systems and are not resistant to high temperatures, while inorganic coatings have weak adhesion and poor flexibility due to their brittleness. The preparation conditions are harsh, and thick coatings are required to achieve certain effects, making them difficult to adapt to the small spaces of precision equipment. For example, in the existing technology, the insulating varnish prepared with an epoxy resin matrix in patent CN118222159A has problems such as easy decomposition at high temperatures, excessive degradation of insulation performance at high temperatures, and excessively thick coatings; and although patent CN115418121A optimizes temperature resistance through an iron-based formula, its multi-stage high-temperature curing process has strict requirements on equipment, and the maximum curing temperature reaches 540℃-620℃, which limits industrial application scenarios.

[0003] Therefore, there is an urgent need to develop a new environmentally friendly coating system that combines ultra-thin coating and high-temperature insulation stability. Summary of the Invention

[0004] The present invention aims to overcome the problems of prior art insulating coatings, such as poor high-temperature resistance, relatively thick thickness, and the presence of organic solvents. The invention provides a water-based organosilicon high-temperature insulating coating and a preparation method. The coating uses a water-based organosilicon resin as a film-forming material, combined with a low-melting-point fluxing filler and an insulating filler with good insulation properties to improve the coating's high-temperature resistance and electrical insulation performance.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A water-based organosilicon high-temperature resistant insulating coating, comprising the following raw materials, calculated by mass: 80 parts of water-based organosilicon resin, 12 parts of fluxing filler, 8 parts of insulating filler, 1.1-6.2 parts of reinforcing filler, 1.5-3 parts of additive, and 3.9-11.7 parts of water;

[0007] The coating prepared by the coating has a thickness of 120±10 μm, an adhesion of level 1 to 2, a pencil hardness of 2H to 3H, and an impact resistance of 40kg·cm to 50kg·cm.

[0008] The water-based organic silicone resin is a water-based methylphenyl silicone resin.

[0009] The fluxing filler is a low-melting-point glass powder, which includes glass powder A with a molten temperature range of 350°C to 450°C and glass powder B with a molten temperature range of 440°C to 600°C; in terms of mass ratio, the ratio of glass powder A to glass powder B is (1 to 5): (1 to 5).

[0010] The insulating filler comprises synthetic mica powder and silicon micropowder, wherein the synthetic mica powder comprises 6 parts and the silicon micropowder comprises 2 parts by mass.

[0011] The reinforcing filler comprises 1.1 to 3.3 parts of aluminum oxide with a particle size of 100 nm to 300 nm and 0 to 4 parts of talc powder with a particle size of 5 μm to 10 μm.

[0012] The aluminum oxide is either flaky nano aluminum oxide or spherical aluminum oxide.

[0013] The auxiliary agent comprises, by weight, 1 to 2 parts of a dispersant and 0.5 to 1 part of a defoaming agent.

[0014] The preparation method of the water-based organic silicon high-temperature resistant insulating coating comprises the following steps: uniformly mixing water-based organic silicon resin, flux filler, insulating filler, reinforcing filler, additive and water according to parts by mass, and then grinding the mixture in a sand mill for 1 to 2 hours until the grinding fineness is less than 30 μm.

[0015] Compared with the prior art, the present invention is beneficial in that:

[0016] The present invention uses water-based high-temperature resistant silicone resin as a film-forming material and water as a solvent, and the water-based high-temperature resistant insulating coating provided is clean, environmentally friendly and pollution-free. The present invention improves the high-temperature resistance and insulation properties of the water-based high-temperature resistant insulating coating by adding low-melting-point fluxing fillers with different melting temperature ranges, multi-scale insulating fillers and reinforcing fillers. Nano-scale flaky or spherical alumina is distributed in micron-sized particles such as silicon micropowder and talcum powder. The low-melting-point fluxing filler, in a molten state, bonds the functional fillers in the system and the SiO2 ash formed by the silicone resin after high temperature, forming a continuous, complete and dense protective layer on the surface of the substrate to prevent the coating from cracking.

[0017] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1Optical photographs of Example 8 before and after ablation at 600°C: (a) before ablation; (b) after ablation;

[0019] Figure 2 Comparison of TEM morphologies of flaky alumina and spherical alumina: (a) flaky alumina; (b) spherical alumina. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0021] The present invention mainly prepares a water-based organic silicon high-temperature resistant insulating coating on the surface of a rigid substrate by thermal curing, and then improves the high-temperature resistant insulating performance of the coating by adjusting the dosage of nano-alumina and talcum powder, and finally prepares a coating with good high-temperature resistant insulating performance.

[0022] The present invention mixes flaky aluminum oxide and synthetic mica powder in proportion to obtain a mixture as an insulating filler. Flaky aluminum oxide has a two-dimensional layered structure (such as Figure 2 (a) shows), with a large specific surface area and low bulk density; while spherical alumina has an isotropic three-dimensional structure (such as Figure 2 (b) shows a smooth surface and dense packing. Compared to spherical alumina, the layered structure of flake alumina effectively blocks heat conduction paths and current migration, resulting in lower thermal conductivity and higher breakdown voltage. Its superior interlayer bonding and oxygen diffusion barrier properties also provide it with improved high-temperature stability.

[0023] In an embodiment of the present invention, water-based methylphenyl silicone resin is used as the water-based silicone resin; glass powder A covering the melting temperature range between 350°C and 450°C and glass powder B covering the melting temperature range between 440°C and 600°C are used as low-melting-point glass powders; a mixture of synthetic mica powder with a particle size of 5μm to 10μm and silicon micropowder with a particle size of 5μm to 10μm is used as an insulating filler; a mixture of spherical alumina or flaky alumina with a particle size of 100nm to 300nm and talc powder with a particle size of 5μm to 10μm is used as a reinforcing filler; and a dispersant and a defoaming agent are used as auxiliary agents.

[0024] Example 1:

[0025] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C, and glass powder B with a melting temperature range of 440°C to 600°C (where the weight ratio of the two low-melting-point glass powders A and B is 1:5), 6 parts of mica powder, 2 parts of silica powder, 1.1 parts of spherical alumina with a particle size of 200 nm, 3.9 parts of water, 1 part of dispersant, and 0.5 parts of defoamer are added to a grinding jar, shaken evenly, and then ground in a sand mill for 1 to 2 hours to a fineness of less than 30 μm. The coating is then filtered through a 200-mesh filter cloth to obtain the coating.

[0026] Example 2:

[0027] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 5:1, 6 parts of mica powder, 2 parts of silicon micropowder, 1.1 parts of spherical alumina with a particle size of 200nm, 3.9 parts of water, 1 part of dispersant, and 0.5 parts of defoaming agent are added to a grinding jar by mass, shaken well, and put into a sand mill for grinding for 1 to 2 hours. The grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0028] Example 3:

[0029] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 1.1 parts of flaky alumina with a particle size of 200nm, 3.9 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar by mass, shaken well, put into a sand mill for grinding for 1 to 2 hours, and the grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0030] Example 4:

[0031] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 1.1 parts of spherical alumina with a particle size of 200nm, 3.9 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar according to mass parts, shaken well, put into a sand mill for grinding for 1 to 2 hours, and the grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0032] Example 5:

[0033] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 1.1 parts of flaky alumina with a particle size of 100 nm, 3.9 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar by mass, shaken well, and put into a sand mill for grinding for 1 to 2 hours, with a grinding fineness of less than 30 μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0034] Example 6:

[0035] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 1.1 parts of spherical alumina with a particle size of 100 nm, 3.9 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar according to mass, shaken well, put into a sand mill for grinding for 1 to 2 hours, and the grinding fineness is less than 30 μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0036] Example 7:

[0037] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 1.1 parts of flaky alumina with a particle size of 300nm, 3.9 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar by mass, shaken well, put into a sand mill for grinding for 1 to 2 hours, and the grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0038] Example 8:

[0039] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 1.1 parts of spherical alumina with a particle size of 300nm, 3.9 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar according to mass parts, shaken well, put into a sand mill for grinding for 1 to 2 hours, and the grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0040] Example 9:

[0041] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 2.2 parts of flaky alumina with a particle size of 100 nm, 7.8 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar according to mass, shaken well, put into a sand mill for grinding for 1 to 2 hours, and the grinding fineness is less than 30 μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0042] Example 10:

[0043] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 2.2 parts of spherical alumina with a particle size of 100 nm, 7.8 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar by mass, shaken well, and put into a sand mill for grinding for 1 to 2 hours, with a grinding fineness of less than 30 μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0044] Example 11:

[0045] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 3.3 parts of flaky alumina with a particle size of 100 nm, 11.7 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar by mass, shaken well, put into a sand mill and ground for 1 to 2 hours, with a grinding fineness of less than 30 μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0046] Example 12:

[0047] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 3.3 parts of flaky alumina with a particle size of 100 nm, 11.7 parts of water, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar by mass, shaken well, put into a sand mill and ground for 1 to 2 hours, with a grinding fineness of less than 30 μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0048] Example 13:

[0049] 80 parts of silicone resin, 12 parts of fluxing filler, glass powder A with a melting temperature range of 350°C to 450°C and glass powder B with a melting temperature range of 440°C to 600°C, wherein the mass ratio of the two low-melting-point glass powders A and B is 1:1, 6 parts of mica powder, 2 parts of silicon micropowder, 2.2 parts of flaky alumina with a particle size of 100 nm, 7.8 parts of water, 4 parts of talc, 2 parts of dispersant, and 1 part of defoaming agent are added to a grinding jar according to mass, shaken well, put into a sand mill for grinding for 1 to 2 hours, and the grinding fineness is less than 30 μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0050] Comparative Example 1:

[0051] 80 parts of silicone resin, 4 parts of flux filler A glass powder, the melting temperature range of glass powder A covers 350℃~450℃, 6 parts of mica powder, 10 parts of titanium dioxide, 2 parts of dispersant, and 1 part of defoamer are added into a grinding jar according to mass, shaken evenly, and put into a sand mill for grinding for 1~2 hours. The grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0052] Comparative Example 2:

[0053] 80 parts of silicone resin, 4 parts of flux filler A glass powder, the molten temperature range of glass powder A covers 350℃~450℃, 6 parts of mica powder, 10 parts of silicon micropowder, 2 parts of dispersant, and 1 part of defoamer are added into a grinding jar according to mass, shaken evenly, and put into a sand mill for grinding for 1~2 hours. The grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0054] Comparative Example 3:

[0055] 80 parts of silicone resin, 4 parts of flux filler B glass powder, the molten temperature range of glass powder B covers 440℃~600℃, 6 parts of mica powder, 10 parts of silicon micropowder, 2 parts of dispersant, and 1 part of defoamer are added into a grinding jar according to mass, shaken evenly, and put into a sand mill for grinding for 1~2h. The grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0056] Comparative Example 4:

[0057] 80 parts of silicone resin, 12 parts of flux filler A glass powder, the molten temperature range of glass powder A covers 350℃~450℃, 6 parts of mica powder, 2 parts of silicon micropowder, 2 parts of dispersant, and 1 part of defoamer are added into a grinding jar according to mass, shaken evenly, and put into a sand mill for grinding for 1~2 hours. The grinding fineness is less than 30μm, and then filtered through a 200-mesh filter cloth to obtain a coating.

[0058] The coatings prepared in each example and comparative example were prepared into corresponding water-based organosilicon high-temperature-resistant insulating coatings using the same process. After curing at room temperature for 7 days, the high-temperature insulation performance test was conducted. The process flow for preparing the water-based organosilicon high-temperature-resistant insulating coating is as follows: using a 250μm scraper for coating, controlling the wet film thickness to 250μm, allowing the coating to dry at room temperature for 30 minutes, then placing it in an oven, holding it at 80°C for 15 minutes, then heating it to 220°C for 30 minutes, and then naturally cooling it to room temperature before removing it, resulting in a water-based organosilicon high-temperature-resistant insulating coating with a thickness of 120±10μm.

[0059] The high-temperature insulation performance test process is as follows: the temperature is raised to 600°C in a muffle furnace and kept at this temperature for 30 minutes. The insulation performance test method is a voltage withstand test, with a leakage current of less than 3mA and a test time of 60 seconds.

[0060] The coating obtained in Example 8 was photographed before and after ablation. The results are as follows: Figure 1 As shown in the figure, it can be seen that the coating has slight yellowing in its initial state, which is mainly caused by the yellowing of the silicone resin during the curing process. The yellowing disappears after firing, indicating that the resin component in the coating has basically disappeared. At this time, the coating mainly relies on the "secondary film formation" of the low-melting-point glass powder to reconnect the various components. Therefore, the coating at this time mainly presents the color of the mineral filler used.

[0061] In addition, the present invention also tested the adhesion, pencil hardness, and impact resistance of the coatings prepared in different embodiments and comparative examples. Adhesion was tested using a crosshatch method, with a crosshatch interval of 3 mm selected based on the coating thickness. Pencil hardness was tested using a pencil hardness tester, using pencils of varying sizes, ranging from 6B to 9H, with the final pencil hardness of the coating determined by the presence of scratches. Impact resistance was also tested using a paint film impactor, where a 1 kg metal ball was raised to different heights and allowed to fall freely onto the coating. The coating's impact resistance was assessed by determining whether it cracked or fell, observing any damage such as cracking or shedding.

[0062] Table 1. Summary of coating properties of products from different examples and comparative examples

[0063]

[0064] * The coating prepared in Comparative Example 3 was completely powdered when ablated at 600°C, making it impossible to test its insulation performance. This shows that the use of a single glass powder has its limitations. This is because glass powder has a temperature range of use and loses its function when heated to a higher temperature because it exceeds the operating temperature range.

Claims

1. A water-based organosilicon high-temperature resistant insulating coating, characterized in that: Calculated by mass, it includes the following raw materials: 80 parts of water-based silicone resin, 12 parts of flux filler, 8 parts of insulating filler, 1.1-6.2 parts of reinforcing filler, 1.5-3 parts of additive, and 3.9-11.7 parts of water; The coating prepared by the coating has a thickness of 120±10 μm, an adhesion of level 1 to 2, a pencil hardness of 2H to 3H, and an impact resistance of 40kg·cm to 50kg·cm.

2. The water-based organosilicon high-temperature resistant insulating coating according to claim 1, characterized in that: The water-based organic silicone resin is a water-based methylphenyl silicone resin.

3. The water-based organosilicon high-temperature resistant insulating coating according to claim 1, characterized in that: The fluxing filler is low-melting-point glass powder, including glass powder A whose melting temperature range is between 350°C and 450°C and glass powder B whose melting temperature range is between 440°C and 600°C.

4. The water-based organosilicon high-temperature resistant insulating coating according to claim 3, characterized in that: In terms of mass ratio, the ratio of glass powder A to glass powder B is (1-5): (1-5).

5. The water-based organosilicon high-temperature resistant insulating coating according to claim 1, characterized in that: The insulating filler comprises synthetic mica powder and silicon micropowder, wherein the synthetic mica powder comprises 6 parts and the silicon micropowder comprises 2 parts by mass.

6. The water-based organosilicon high-temperature resistant insulating coating according to claim 1, characterized in that: The reinforcing filler comprises 1.1 to 3.3 parts of aluminum oxide with a particle size of 100 nm to 300 nm and 0 to 4 parts of talc powder with a particle size of 5 μm to 10 μm.

7. The water-based organosilicon high-temperature resistant insulating coating according to claim 6, characterized in that: The aluminum oxide is either flaky nano aluminum oxide or spherical aluminum oxide.

8. The water-based organosilicon high-temperature resistant insulating coating according to claim 1, characterized in that: The auxiliary agent comprises, by weight, 1 to 2 parts of a dispersant and 0.5 to 1 part of a defoaming agent.

9. A method for preparing the water-based organosilicon high-temperature resistant insulating coating according to any one of claims 1 to 8, characterized in that: The water-based silicone resin, flux filler, insulating filler, reinforcing filler, additives and water are uniformly mixed according to mass, and then put into a sand mill for grinding for 1 hour to 2 hours until the grinding fineness is less than 30 μm.

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