High-temperature-resistant anti-yellowing UV moisture dual-curing conformal coating as well as preparation method and application thereof

Abstract

The invention provides high-temperature-resistant anti-yellowing UV moisture dual-curing conformal coating as well as a preparation method and application thereof, and belongs to the technical field of coatings. The three-proofing paint is prepared from the following components in parts by mass: 40 to 60 parts of UV (ultraviolet) moisture dual-curing resin based on polyorganosilicone dihydric alcohol, 20 to 40 parts of aliphatic polyurethane acrylate resin, 10 to 20 parts of trimethyl cyclohexyl acrylate, 10 to 15 parts of isobornyl acrylate, 5 to 10 parts of ethyoxyl ethyoxyl ethyl acrylate and 5 to 10 parts of decyl acrylate. 3 to 7 parts of a photoinitiator, 0.05 to 0.2 part of a fluorescent indicator, 0.2 to 1 part of a leveling agent, 0.2 to 1 part of a defoaming agent and 0.05 to 0.3 part of a polymerization inhibitor. According to the invention, a poly-organosilicon diol structure is introduced into the dual-cured resin, and the aliphatic polyurethane acrylate resin and various functional acrylate monomers are compounded, so that the prepared conformal coating has excellent high temperature resistance and yellowing resistance.

Description

Technical Field

[0001] This application relates to the field of coating technology, and in particular to a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing conformal coating, its preparation method, and its application. Background Technology

[0002] Conformal coating is a functional protective coating applied to the surface of electronic components for protection against moisture, dust, salt spray, mold, chemical corrosion, and electrical insulation. With the rapid development of industries such as photovoltaic inverters, LED lighting / displays, new energy vehicles, and 5G communications, electronic devices operate at long-term high temperatures, posing unprecedented challenges to the high-temperature resistance, yellowing resistance, and long-term reliability of conformal coatings.

[0003] For the photovoltaic industry, junction boxes and control boards are exposed to high outdoor temperatures for extended periods (internal temperatures can reach 80°C in summer). Traditional conformal coatings are prone to yellowing and cracking, affecting heat dissipation and appearance, and even posing a risk of electrical leakage. In the LED panel industry, high-power LED driver boards generate a lot of heat, and yellowing of the coating reduces luminous efficiency and affects color temperature consistency, severely impacting display or lighting quality. Commonly used protective materials, such as ordinary UV resins or initiators, are prone to oxidation and yellowing at high temperatures. Single UV curing is insufficient to cover shaded areas, and the coating is brittle and easily cracks under thermal cycling.

[0004] Although existing technologies utilize aliphatic polyurethane acrylates or add antioxidants to improve performance, it remains difficult to achieve a comprehensive performance profile of low yellowing, high adhesion, good flexibility, and dual curing under long-term high-temperature extreme conditions. Therefore, developing a high-temperature resistant UV conformal coating that meets the needs of high-temperature applications such as photovoltaics and LEDs has significant market value and technical importance. Summary of the Invention

[0005] This application is made in view of the above-mentioned problems, and its purpose is to provide a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing conformal coating, its preparation method, and its application.

[0006] Specifically, the first aspect of this application provides a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing, three-proof coating, comprising the following components in parts by weight: 40-60 parts of a UV-curable, moisture-resistant dual-curing resin based on polysilicon diol, 20-40 parts of aliphatic polyurethane acrylate resin, 10-20 parts of trimethylcyclohexyl acrylate, 10-15 parts of isoborneol acrylate, 5-10 parts of ethoxyethoxyethyl acrylate, 5-10 parts of decyl acrylate, 3-7 parts of photoinitiator, 0.05-0.2 parts of fluorescent indicator, 0.2-1 parts of leveling agent, 0.2-1 parts of defoamer, and 0.05-0.3 parts of polymerization inhibitor; The method for preparing the UV moisture dual-curing resin based on polyorganosilicon diol includes: mixing polyorganosilicon diol, isophorone diisocyanate, hexamethylene diisocyanate and hydroxyethyl acrylate under a protective atmosphere, and preparing the resin under an organobismuth catalyst.

[0007] Furthermore, the polyorganosilicon diol is α,ω-dihydroxypolydimethylsiloxane with a molecular weight of 1000-2000.

[0008] Furthermore, the NCO content of the UV moisture-curing resin based on polyorganosilicon diol is 6-8% after the reaction is completed, and the NCO functional groups are in excess during the synthesis process.

[0009] Furthermore, the reaction raw materials of the UV moisture dual-curing resin based on polyorganosilicone diol include the following components in parts by weight: 65-75 parts of α,ω-dihydroxypolydimethylsiloxane, 10-15 parts of isophorone diisocyanate, 8-12 parts of hexamethylene diisocyanate, 5-10 parts of hydroxyethyl acrylate, 0.1-0.3 parts of polymerization inhibitor, and 0.05-0.3 parts of catalyst.

[0010] Furthermore, the photoinitiator includes photoinitiator 184 and photoinitiator 2952.

[0011] Furthermore, the organic bismuth catalyst is bismuth isooctanoate.

[0012] The second aspect of this invention provides a method for preparing a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing conformal coating, comprising the following steps: UV moisture dual-curing resin based on polyorganosilicon diol and aliphatic polyurethane acrylate resin are added to the reaction apparatus, and stirred and heated to 55-65℃ under a protective atmosphere. Trimethylcyclohexyl acrylate, isobornyl acrylate, ethoxyethoxyethyl acrylate, and decyl acrylate were added sequentially to the reaction apparatus and stirred until homogeneous. Add the photoinitiator and fluorescent indicator, and stir in the dark until completely dissolved; Finally, add leveling agent, defoamer and polymerization inhibitor and continue stirring for 0.5-1.5 hours; filter to obtain the finished conformal coating.

[0013] Furthermore, the conformal coating is sprayed onto the PCB board, and after curing, the adhesion is ≥0 level.

[0014] Furthermore, the conformal coating forms a dry film thickness of 50-100μm on the aluminum sheet, and is aged at 140-160℃ for 165-170h, with a total color difference of <3.0 before and after aging.

[0015] The third aspect of this application provides an application of a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing conformal coating, which is used for the protection of photovoltaic junction boxes, LED driver boards, or new energy vehicle electronic control modules.

[0016] The present invention has the following beneficial effects: This invention's conformal coating exhibits excellent high-temperature resistance and anti-yellowing properties. The key component is the UV-moisture dual-curing resin based on polysilicon diol, whose molecular structure incorporates polysilicon segments with superior heat and weather resistance, effectively enhancing the coating's stability under long-term high-temperature conditions and inhibiting oxidative yellowing. The combination with aliphatic polyurethane acrylate resin not only avoids the yellowing defects of aromatic structures but also enhances the coating's flexibility and adhesion to the substrate. The blending of various functional acrylate monomers, such as trimethylcyclohexyl acrylate, increases drying speed, toughness, and improves chemical resistance; isoborneol acrylate imparts good flexibility, low curing shrinkage, and high reactivity; ethoxyethoxyethyl acrylate enhances heat resistance and gloss; and decyl acrylate further improves the coating's flexibility and wettability to the substrate, achieving a balance between workability and post-curing performance.

[0017] Furthermore, the fluorescent indicator added to the formula allows the cured coating to emit clear fluorescence under ultraviolet light, facilitating visual inspection of the coating's uniformity and coverage integrity, effectively preventing quality issues such as missed areas or thin coatings. The synergistic effect of the leveling agent and defoamer ensures a smooth and even coating surface during application, reducing defects such as pinholes and craters, further improving the coating's appearance and protective effect. The appropriate addition of a polymerization inhibitor effectively prevents premature gelation of the coating during storage and transportation, ensuring good storage stability. These combined characteristics enable the conformal coating of this application to meet the stringent requirements of high-temperature resistance, yellowing resistance, and high reliability in applications such as photovoltaic junction boxes, LED driver boards, and new energy vehicle electronic control modules. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a comparison image of the UV moisture dual-curing resin before and after the high-temperature yellowing test in Example 1; Figure 2This is a comparison chart of the UV moisture dual-curing resin before and after the high-temperature yellowing test in Comparative Example 1. Figure 3 This is a comparison chart of the UV moisture dual-curing resin before and after the high-temperature yellowing test in Comparative Example 2.

[0020] The purpose, features, and advantages of this accompanying drawing will be further explained in conjunction with the embodiments and with reference to the accompanying drawing. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0022] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0023] The first aspect of this application provides a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing, three-proof coating, comprising the following components in parts by weight: 40-60 parts of a UV-curable, moisture-resistant dual-curing resin based on polysilicon diol, 20-40 parts of aliphatic polyurethane acrylate resin, 10-20 parts of trimethylcyclohexyl acrylate, 10-15 parts of isoborneol acrylate, 5-10 parts of ethoxyethoxyethyl acrylate, 5-10 parts of decyl acrylate, 3-7 parts of photoinitiator, 0.05-0.2 parts of fluorescent indicator, 0.2-1 parts of leveling agent, 0.2-1 parts of defoamer, and 0.05-0.3 parts of polymerization inhibitor; The method for preparing the UV moisture dual-curing resin based on polyorganosilicon diol includes: mixing polyorganosilicon diol, isophorone diisocyanate, hexamethylene diisocyanate and hydroxyethyl acrylate under a protective atmosphere, and preparing the resin under an organobismuth catalyst.

[0024] The conformal coating of this invention exhibits excellent high-temperature resistance and anti-yellowing properties. The key component is the UV-moisture dual-curing resin based on polysilicon diol, whose molecular structure incorporates polysilicon segments with superior heat and weather resistance, effectively enhancing the coating's stability under long-term high-temperature conditions and inhibiting oxidative yellowing. The combination with aliphatic polyurethane acrylate resin not only avoids the yellowing defects of aromatic structures but also enhances the coating's flexibility and adhesion to the substrate. The blending of various functional acrylate monomers, such as trimethylcyclohexyl acrylate, increases drying speed, toughness, and improves chemical resistance; isobornyl acrylate imparts good flexibility, low curing shrinkage, and high reactivity; ethoxyethoxyethyl acrylate enhances heat resistance and gloss; and decyl acrylate further improves the coating's flexibility and wettability to the substrate, achieving a balance between workability and post-curing performance.

[0025] The mass fraction of the UV-moisture dual-curing resin based on polyorganosilicon diol can be any value such as 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, etc. This resin combines the high temperature resistance and flexibility of organosilicon with the low yellowing properties of aliphatic isocyanates, making it suitable for high-performance conformal coating systems. As the main film-forming substance, it provides the flexibility of the coating and the UV and moisture dual-curing mechanism.

[0026] The aliphatic polyurethane acrylate resin, preferably CN983, can be in parts by weight of 20, 25, 30, 35, or 40. This resin has excellent weather resistance, flexibility, and adhesion, and is used to improve the chemical resistance, abrasion resistance, and curing speed of the coating film. It has good compatibility with silicone resin and can further improve the comprehensive mechanical properties of the coating.

[0027] The trimethylcyclohexyl acrylate can be in the form of 10, 12, 15, 18, or 20 parts by weight, etc., and is used to increase the drying speed and toughness of the system, participate in the curing reaction, and improve the crosslinking density and chemical resistance of the coating.

[0028] The mass fraction of isoborneol acrylate (IBOA) can be selected as 10 parts, 11 parts, 13 parts, 15 parts, etc., which endows the system with good flexibility, low curing shrinkage and high reactivity.

[0029] The mass fraction of the ethoxyethoxyethyl acrylate can be 5 parts, 6 parts, 8 parts, 10 parts, etc. As a bifunctional active diluent, it can significantly improve the crosslinking density and heat resistance of the coating, and enhance the hardness and scratch resistance of the coating.

[0030] The mass fraction of decyl acrylate (DA) can be selected as 5 parts, 7 parts, 8 parts, 10 parts, etc. Its long-chain alkyl structure can effectively improve the flexibility of the coating and the wettability of the substrate, reduce the internal stress of the coating, and improve its stability under thermal cycling conditions.

[0031] The photoinitiator includes photoinitiator 184 and photoinitiator 2952. Photoinitiator 184 and photoinitiator 2952 work synergistically to achieve efficient initiation. Among them, 2952 is a liquid low-yellowing initiator, which helps to improve the deep curing effect and match the LED light source.

[0032] The fluorescent indicator (such as OB-1) is used to detect the coverage integrity of the coating under ultraviolet light.

[0033] The leveling agent Tego 432 improves the leveling properties of the paint film and prevents pinholes.

[0034] The defoamer Tego 902 effectively eliminates bubbles during the production and spraying process.

[0035] The polymerization inhibitor (such as hydroquinone) prevents the resin from polymerizing during storage, ensuring product stability.

[0036] In this embodiment, the preparation method of the UV moisture dual-curing resin based on polyorganosilicone diol is as follows: α,ω-dihydroxypolydimethylsiloxane (polyorganosilicone diol) with a molecular weight of 1000-2000 is subjected to dehydration treatment to remove the interference of moisture on the isocyanate reaction; wherein IPDI provides a cyclic structure to enhance the heat resistance and rigidity of the resin, and HDI is an aliphatic linear isocyanate, which helps to improve flexibility and reactivity; Subsequently, under nitrogen protection, isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) were added to the reaction system, along with an environmentally friendly catalyst, bismuth isooctanoate, and a polymerization inhibitor (hydroquinone). The temperature was raised to 75-85℃ and the reaction was carried out for 1.5-2.5 hours to allow the isocyanate groups (-NCO) to fully react with the hydroxyl groups (-OH) of the diol, forming a prepolymer with terminal isocyanates. Next, hydroxyethyl acrylate (HEA) is slowly added dropwise, with the addition time controlled at approximately 0.5-1.5 hours. After the addition is complete, the reaction is continued at the specified temperature for 3 hours, allowing the hydroxyl groups to react with the remaining -NCO groups, introducing UV-curable acrylate functional groups. The -NCO content is periodically sampled and tested; if the NCO content is 6-8%, the reaction is confirmed to be complete. Heating is then stopped, and the product is discharged to obtain an acryloxy-terminated polyurethane prepolymer resin with dual UV and moisture curing capabilities.

[0037] This resin combines the high-temperature resistance and flexibility of silicone with the low yellowing properties of aliphatic isocyanates, making it suitable for high-performance conformal coating systems.

[0038] The mass fractions of the reaction raw materials for the UV moisture dual-curing resin based on polyorganosilicone diol are: 65-75 parts of α,ω-dihydroxypolydimethylsiloxane, 10-15 parts of isophorone diisocyanate, 8-12 parts of hexamethylene diisocyanate, 5-10 parts of hydroxyethyl acrylate, 0.1-0.3 parts of polymerization inhibitor, and 0.05-0.3 parts of catalyst.

[0039] The organic bismuth catalyst is bismuth isooctanoate. The polymerization inhibitor is hydroquinone.

[0040] A second aspect of the present invention provides a method for preparing a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing conformal coating, comprising the following steps: UV moisture-curing resin based on polysilicon diol and aliphatic polyurethane acrylate resin are added to a reaction apparatus and stirred and heated to 55-65°C under a protective atmosphere (nitrogen). Trimethylcyclohexyl acrylate, isobornyl acrylate, ethoxyethoxyethyl acrylate, and decyl acrylate were added sequentially to the reaction apparatus and stirred until homogeneous. Add the photoinitiator and fluorescent indicator, and stir in the dark until completely dissolved; Finally, add leveling agent, defoamer and polymerization inhibitor and continue stirring for 0.5-1.5 hours; filter (3μm filter element) to obtain the finished conformal coating.

[0041] In this embodiment, the conformal coating is sprayed onto the PCB board, and after curing, the adhesion is ≥0 level and the insulation resistance is >1012Ω.

[0042] In this embodiment, the conformal coating forms a dry film thickness of 50-100μm on the aluminum sheet and is aged at 140-160℃ for 165-170h. The total color difference before and after aging is <3.0.

[0043] Example The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Unless otherwise stated, all reagents used in the examples are available commercially or synthesized using conventional methods and are ready for use without further processing. Unless otherwise stated, all instruments used in the examples are available commercially.

[0044] Example 1 A high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing, three-proof coating comprises the following components in parts by weight: 50 parts of a UV-curable, moisture-resistant dual-curing resin based on polysilicon diol, 30 parts of aliphatic polyurethane acrylate resin (CN983), 15 parts of trimethylcyclohexyl acrylate (TMCHA), 12 parts of isobornyl acrylate (IBOA), 8 parts of ethoxyethoxyethyl acrylate (EOEOEA), 7 parts of decyl acrylate, 3 parts of photoinitiator 184, 2 parts of photoinitiator 2952, 0.1 parts of fluorescent indicator (OB-1), 0.8 parts of leveling agent Tego432, 0.6 parts of defoamer Tego902, and 0.2 parts of polymerization inhibitor (hydroquinone).

[0045] The aliphatic polyurethane acrylate resin, trimethylcyclohexyl acrylate, ethoxyethoxyethyl acrylate, decyl acrylate and other components are all from Changxing Materials Industry (Guangdong) Co., Ltd.

[0046] The preparation method of the high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing, three-proof paint is as follows: Preparation of UV moisture-curing dual-curing resin based on polyorganosilicone diol: 72.2 parts of α,ω-dihydroxypolydimethylsiloxane (polyorganosilicone diol) were heated to 110℃ under nitrogen protection, vacuum dehydrated for 1 hour to remove trace moisture, and then cooled to below 40℃; 12 parts of isophorone diisocyanate, 9.1 parts of hexamethylene diisocyanate, 6.3 parts of hydroxyethyl acrylate, 0.11 parts of bismuth isooctanoate and 0.16 parts of hydroquinone were added to the reaction system, and the mixture was heated to 80℃ and reacted for 2 hours. UV moisture-curing resin based on polysilicon diol and aliphatic polyurethane acrylate resin were added to a stirred tank, nitrogen gas was purged, and the mixture was stirred and heated to 60°C. Trimethylcyclohexyl acrylate, isobornyl acrylate, ethoxyethoxyethyl acrylate and decyl acrylate were added sequentially to the reaction apparatus and stirred until homogeneous. Add the photoinitiator and fluorescent indicator, and stir in the dark until completely dissolved; Finally, add leveling agent, defoamer and polymerization inhibitor and continue stirring for 1 hour; filter to obtain the finished conformal coating.

[0047] Example 2 This embodiment is basically the same as Embodiment 1, except that the conformal coating comprises the following components in parts by weight: 45 parts of UV moisture dual-curing resin based on polysilicon diol, 25 parts of aliphatic polyurethane acrylate resin (CN983), 18 parts of trimethylcyclohexyl acrylate, 12 parts of isobornyl acrylate (IBOA), 6 parts of ethoxyethoxyethyl acrylate, 7 parts of decyl acrylate, 2.5 parts of photoinitiator 184, 1.5 parts of photoinitiator 2952, 0.15 parts of fluorescent indicator (OB-1), 0.4 parts of leveling agent Tego432, 0.5 parts of defoamer Tego902, and 0.15 parts of polymerization inhibitor (hydroquinone).

[0048] Example 3 This embodiment is basically the same as Embodiment 1, except that the conformal coating comprises the following components in parts by weight: 55 parts of UV moisture dual-curing resin based on polysilicon diol, 35 parts of aliphatic polyurethane acrylate resin (CN983), 19 parts of trimethylcyclohexyl acrylate, 14 parts of isobornyl acrylate (IBOA), 9 parts of ethoxyethoxyethyl acrylate, 6 parts of decyl acrylate, 2.2 parts of photoinitiator 184, 1.3 parts of photoinitiator 2952, 0.08 parts of fluorescent indicator (OB-1), 0.3 parts of leveling agent Tego432, 0.45 parts of defoamer Tego902, and 0.1 parts of polymerization inhibitor (hydroquinone).

[0049] Example 4 This embodiment is basically the same as Embodiment 1, except that the conformal coating comprises the following components in parts by weight: 42 parts of UV moisture-curing resin based on polysilicon diol, 28 parts of aliphatic polyurethane acrylate resin (CN983), 16 parts of trimethylcyclohexyl acrylate, 12 parts of isobornyl acrylate (IBOA), 6 parts of ethoxyethoxyethyl acrylate, 9 parts of decyl acrylate, 3.5 parts of photoinitiator 184, 2.5 parts of photoinitiator 2952, 0.2 parts of fluorescent indicator (OB-1), 0.6 parts of leveling agent Tego432, 0.9 parts of defoamer Tego902, and 0.25 parts of polymerization inhibitor (hydroquinone).

[0050] Example 5 This embodiment is basically the same as Example 1, except that the method for preparing the UV moisture dual-curing resin based on polyorganosilicone diol is as follows: 69 parts of α,ω-dihydroxypolydimethylsiloxane are heated to 110°C under nitrogen protection, vacuum dehydrated for 1 hour to remove trace amounts of moisture, and then cooled to below 40°C; 14 parts of isophorone diisocyanate, 9 parts of hexamethylene diisocyanate, 9 parts of hydroxyethyl acrylate, 0.24 parts of bismuth isooctanoate and 0.15 parts of hydroquinone are added to the reaction system, and the mixture is heated to 80°C and reacted for 2 hours.

[0051] Comparative Example 1 This comparative example is basically the same as Example 1, except that the UV moisture dual-curing resin raw material α,ω-dihydroxypolydimethylsiloxane (Mn=1000, Wacker HD1) is replaced with polyester diol (Mn=1000), Covestro Acclaim® 1210.

[0052] Comparative Example 2 This comparative example is basically the same as Example 1, except that the UV moisture dual-curing resin raw material α,ω-dihydroxypolydimethylsiloxane is replaced with polyether diol (Mn=1000), Wanhua Chemical PPG1000.

[0053] Experimental Case 1 Following the descriptions in Examples 1, 1, and 2, UV moisture-curing resins were prepared using polysilicon diols, polyester diols, and polyether diols as soft segments, respectively. The specific steps were as follows: The selected diol was added to a reaction vessel and heated to 110°C under nitrogen protection. Vacuum dehydration was performed for 1 hour to remove trace amounts of moisture; then the temperature was lowered to below 40°C. Isophorone diisocyanate, hexamethylene diisocyanate, a polymerization inhibitor (hydroquinone), and a catalyst (bismuth isooctanoate) were added. The temperature was further increased to 80°C under nitrogen protection, and the reaction was continued for 2 hours to allow the isocyanate groups to fully react with the diol to form a prepolymer. Then, hydroxyethyl acrylate (HEA) was slowly added dropwise, with the addition time controlled to approximately 1 hour. After the addition was complete, the reaction was maintained at this temperature for 3 hours. Samples were taken to detect the isocyanate (-NCO) content. The reaction was considered complete when the -NCO value stabilized at 6-8%. The material was then cooled and discharged to obtain a UV moisture-curing resin with acryloyl groups at the end of its oxidation state.

[0054] The amounts of each component in the UV moisture dual-curing resins prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown in Table 1.

[0055]

[0056] The NCO value of the UV moisture dual-curing resin prepared according to the above method was measured when the reaction was completed, as shown in Table 2.

[0057]

[0058] Take 100g each of the UV moisture-curing resins prepared in Example 1, Comparative Examples 1 and 2, add 3 wt% photoinitiator 184, stir evenly at 60℃, degas under vacuum, and then coat the film onto a clean aluminum sheet using a film scraper to achieve a wet film thickness of 100µm; cure under a mercury lamp light source (energy ≥3000 mJ / cm²). 2 The initial L*a*b* value was measured; the sample was placed in an oven and baked at 150℃ for 168 hours; after cooling, the L*a*b* value after aging was measured, and the ΔE value was calculated. The results are shown in Table 3. Figure 1-3 .

[0059]

[0060] As shown in Table 3, the UV-cured resin of Example 1, which uses polysilicon diol as the soft segment, exhibits a total color difference ΔE value of only 1.8 after aging at 150°C for 168 hours. This is significantly lower than the resins using polyester diol (Comparative Example 1, ΔE=4.5) and polyether diol (Comparative Example 2, ΔE=5.5) as the soft segment. This is likely because the polysilicon diol used in Example 1 contains a large number of Si-O-Si bonds in its molecular structure. These chemical bonds have extremely high bond energies, far exceeding those of ester bonds in polyester diol and ether bonds in polyether diol. The higher bond energy makes the Si-O-Si bonds less prone to breakage or oxidative decomposition at high temperatures, thus reducing the chromophores or degradation products generated by molecular chain breakage. Simultaneously, the polysilicon segments possess excellent flexibility and low surface energy, reducing the degree of oxidation of the resin during high-temperature aging. In addition, the introduction of organosilicon segments can improve the thermal stability of the resin and increase its glass transition temperature, so that the resin can maintain structural stability at high temperatures and is less prone to yellowing caused by thermo-oxidative degradation.

[0061] In contrast, polyester diols are prone to ester bond hydrolysis or thermal decomposition at high temperatures, producing small molecules such as carboxylic acids. Further oxidation of these substances exacerbates color changes. The ether bonds in polyether diols are more susceptible to attack from high temperatures and oxygen, undergoing oxidative chain scission and generating aldehydes, ketones, and other groups that easily cause yellowing. Therefore, the ΔE values ​​of the resins in Comparative Examples 1 and 2 after high-temperature aging are significantly higher than those in Example 1. This fully demonstrates that the UV moisture-curing resin prepared using polyorganosilicon diols as the soft segment in this invention possesses excellent high-temperature resistance and anti-yellowing properties.

[0062] Experimental Case 2 Conformal coatings were prepared according to the methods of Example 1, Comparative Example 1, and Comparative Example 2, and their performance before curing, UV curing, and after curing were tested. The results are shown in Table 4.

[0063]

[0064] As shown in Table 4, the conformal coating prepared in Example 1 had the same appearance as Comparative Examples 1 and 2 before curing; it was colorless and transparent. Its viscosity was 115 mPa·s, between 126 mPa·s of Comparative Example 1 and 108 mPa·s of Comparative Example 2, and its density of 1.092 g / cm³ was slightly higher than both. Regarding UV curing performance, Example 1 showed better performance at LED 365 nm (3000 mJ / cm³). 2 LED 395nm (3000mJ / cm) 2 ) and mercury lamp (3000mJ / cm) 2 Under the illumination of the three light sources, the surface of the cured film reached a dry state; however, Comparative Example 2, after curing under the LED 395nm light source, still showed a sticky surface, indicating that its curing was incomplete under this specific light source condition. In the post-curing performance test, the aluminum sheet adhesion of Example 1 reached level 0, which was better than the level 1 of Comparative Examples 1 and 2; the PCB adhesion of all three was level 0, showing good performance. All three exhibited fluorescence and had similar solid content, all above 99%. In terms of volume resistivity, Example 1 was 6.0 × 10⁻⁶. 14 .cm, in Comparative Example 1 (6.8×10 14 .cm) and Comparative Example 2 (5.0×10 14 Between .cm). Overall, the conformal coating of Example 1 maintains good overall performance, and shows particular advantages in aluminum sheet adhesion and curing effect under a specific light source (LED 395nm).

[0065] Experimental Case 3 The conformal coatings prepared in Example 1, Comparative Example 1, and Comparative Example 2 were sprayed onto aluminum test pieces (wet film 50-100 μm) using a hand spray gun and cured with a mercury lamp. The curing energy was 3000 mJ / cm. 2 After standing at room temperature for 72 hours, a high-temperature yellowing test at 150℃ / 168h was conducted. The test results are shown in Table 5.

[0066]

[0067] As shown in Table 5, after 168 hours of high-temperature yellowing resistance testing at 150°C, the total color difference ΔE value of the conformal coating in Example 1 was 2.5, significantly lower than that of Comparative Example 1 (6.8) and Comparative Example 2 (8.3). This further confirms the significant advantage of using polysilicon diol as the soft segment in UV moisture dual-curing resin in improving the high-temperature resistance and yellowing resistance of conformal coatings. In terms of appearance, no cracking was observed in any of the three groups, indicating that they maintained good coating integrity during high-temperature aging. In the adhesion test, the aluminum sheet adhesion of Example 1 remained at level 0, while Comparative Example 1 and Comparative Example 2 decreased to level 1, indicating that the conformal coating of Example 1 maintained strong adhesion to the substrate after high-temperature aging. In the bending test, all three passed the 1mm mandrel test, demonstrating good flexibility; even after high-temperature aging, the coating did not crack or peel due to increased brittleness. These results demonstrate that the conformal coating of the present invention not only possesses excellent high-temperature resistance and anti-yellowing properties, but also maintains good adhesion and flexibility under high-temperature conditions, exhibiting outstanding overall performance.

[0068] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing, three-proof paint, characterized in that, The product comprises the following components in parts by weight: 40-60 parts of UV moisture-curing resin based on polysilicon diol, 20-40 parts of aliphatic polyurethane acrylate resin, 10-20 parts of trimethylcyclohexyl acrylate, 10-15 parts of isobornyl acrylate, 5-10 parts of ethoxyethoxyethyl acrylate, 5-10 parts of decyl acrylate, 3-7 parts of photoinitiator, 0.05-0.2 parts of fluorescent indicator, 0.2-1 parts of leveling agent, 0.2-1 parts of defoamer, and 0.05-0.3 parts of polymerization inhibitor; The method for preparing the UV moisture dual-curing resin based on polyorganosilicon diol includes: mixing polyorganosilicon diol, isophorone diisocyanate, hexamethylene diisocyanate and hydroxyethyl acrylate under a protective atmosphere, and preparing the resin under an organobismuth catalyst.

2. The high-temperature resistant, anti-yellowing, UV-curing, moisture-resistant dual-curing conformal coating according to claim 1, characterized in that, The polyorganosilicon diol is α,ω-dihydroxypolydimethylsiloxane with a molecular weight of 1000-2000.

3. The high-temperature resistant, anti-yellowing, UV-curing, moisture-resistant dual-curing conformal coating according to claim 2, characterized in that, The NCO content of the UV moisture dual-curing resin based on polyorganosilicone diol is 6-8% after the reaction is completed.

4. The high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing conformal coating according to claim 2, characterized in that, The reaction raw materials of the UV moisture dual-curing resin based on polyorganosilicone diol include the following components in parts by weight: 65-75 parts of α,ω-dihydroxypolydimethylsiloxane, 10-15 parts of isophorone diisocyanate, 8-12 parts of hexamethylene diisocyanate, 5-10 parts of hydroxyethyl acrylate, 0.1-0.3 parts of polymerization inhibitor, and 0.05-0.3 parts of catalyst.

5. The high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing conformal coating according to claim 1, characterized in that, The photoinitiators include photoinitiator 184 and photoinitiator 2952.

6. The high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing conformal coating according to claim 1, characterized in that, The organic bismuth catalyst is bismuth isooctanoate.

7. A method for preparing a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing, three-proof coating, characterized in that, The preparation of the high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant, dual-curing, three-proof coating according to any one of claims 1-6 includes the following steps: UV moisture dual-curing resin based on polyorganosilicon diol and aliphatic polyurethane acrylate resin are added to the reaction apparatus, and stirred and heated to 55-65℃ under a protective atmosphere. Trimethylcyclohexyl acrylate, isobornyl acrylate, ethoxyethoxyethyl acrylate, and decyl acrylate were added sequentially to the reaction apparatus and stirred until homogeneous. Add the photoinitiator and fluorescent indicator, and stir in the dark until completely dissolved; Finally, add leveling agent, defoamer and polymerization inhibitor and continue stirring for 0.5-1.5 hours; filter to obtain the finished conformal coating.

8. The preparation method of the high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing conformal coating according to claim 7, characterized in that, The conformal coating is sprayed onto the PCB board, and after curing, the adhesion is ≥0 level.

9. The preparation method of the high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing conformal coating according to claim 7, characterized in that, The conformal coating forms a dry film thickness of 50-100μm on the aluminum sheet and is aged at 140-160℃ for 165-170h. The total color difference before and after aging is < 3.

0.

10. The application of a high-temperature resistant, anti-yellowing, UV-curable, moisture-resistant dual-curing conformal coating as described in any one of claims 1-6, characterized in that, The conformal coating is used for the protection of photovoltaic junction boxes, LED driver boards, or electronic control modules of new energy vehicles.

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