High-temperature-resistant erasable outdoor conformal coating as well as preparation method and erasing method thereof

Abstract

The invention provides high-temperature-resistant erasable outdoor three-proofing paint as well as a preparation method and an erasing method thereof. The conformal coating comprises a solvent, methyl silicone oil, hydrogen-containing silicone oil, a catalyst, a styrene-isoprene block copolymer, a styrene-butadiene block copolymer and a styrene-ethylene-butylene-styrene block copolymer; the mass of the styrene-isoprene block copolymer accounts for 1%-15% of the total mass of the conformal coating, the mass of the styrene-butadiene block copolymer accounts for 1%-15% of the total mass of the conformal coating, and the mass of the styrene-ethylene-butylene-styrene block copolymer accounts for 1%-5% of the total mass of the conformal coating. The coating can effectively prevent moisture, salt mist and chemical corrosion, is high in curing speed, can maintain the performance in a high-temperature environment, and is suitable for the surface of a part with relatively high requirements on high temperature resistance, hydrophobicity and three-proofing. The cured film formed by erasing the conformal coating by adopting the matched erasing solvent is good in removal effect and free of residues, and is particularly suitable for precise devices such as electronic circuits and the like.

Description

Technical Field

[0001] The present application relates to the technical field of coatings, and in particular to a high-temperature resistant and erasable outdoor conformal coating and a preparation method and erasing method thereof. Background Art

[0002] Conformal coating is a special coating designed for electronic circuit boards. After curing, it can form a protective film with excellent properties such as moisture-proof, dust-proof and corrosion-resistant. It can be widely used in civil, automotive, aerospace and marine fields to improve the reliability and service life of electronic equipment.

[0003] A significant problem in the existing conformal coating technology is that the resin molecular structure in the conformal coating is easily damaged in a high temperature environment, causing the cured film to lose its original hardness and toughness, thus affecting its protective effect. This limits the application of existing conformal coatings in high temperature environments and cannot meet the needs of some specific fields for high temperature stability.

[0004] The second problem in the prior art is the slow curing speed. The traditional three-conformal coating curing process often takes a long time, which not only affects the production efficiency, but also may cause the coating to be contaminated or damaged during the curing process. Especially in some occasions that require rapid production, the slow curing speed has become a key factor restricting the application of three-conformal coatings.

[0005] At present, conformal coatings are usually used on precision circuit boards such as 5G boards and drone boards. If such circuit boards fail at the customer site, they usually need to be returned to the original manufacturer for repair. However, on the one hand, the cost of returning to the original manufacturer is high, and on the other hand, even if they are returned to the original manufacturer, they may not be successfully repaired. Therefore, equipment operators have proposed to equipment manufacturers that they can achieve on-site repairability while ensuring high reliability, which can increase the reuse rate of boards and reduce operating costs.

[0006] In response to this situation, the third problem in the prior art is that the three-proof cured film layer on the surface of the precision circuit board needs to be removed during maintenance. The customer site does not have sophisticated paint removal equipment, making it difficult to remove the three-proof paint on the precision circuit board. Traditional three-proof paint removal methods, such as knife cutting, scraping, dry ice cleaning, steel brushes, and brushes, are inefficient and cannot be applied to precision circuit boards, causing irreversible damage to electronic components. The use of general chemical solvents to remove the three-proof paint is often not thorough, resulting in the new coating being unable to adhere effectively and easily falling off or peeling off. At the same time, the residue of chemical solvents may also cause harm to the coated products and the environment.

[0007] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or known technology. Summary of the invention

[0008] In view of this, the purpose of the present application is to provide a high-temperature resistant and erasable outdoor conformal paint and its preparation method and erasure method, so as to at least simultaneously solve the problems of slow curing speed, poor high-temperature resistance and difficulty in repair of conformal paint in the prior art. The present application can effectively prevent moisture, salt spray and chemical corrosion, has a fast curing speed, and can maintain its performance in a high-temperature environment. It is suitable for the surface of components with high requirements for high-temperature resistance, hydrophobicity, and three-proof. At the same time, the present application uses a matching erasing solvent to erase the cured film formed by the conformal paint, and the removal effect is good without residue, which is especially suitable for precision devices such as electronic circuits.

[0009] In the first aspect, the present application provides a high-temperature resistant and erasable outdoor conformal paint, which includes a solvent, methyl silicone oil, hydrogenated silicone oil, a catalyst, a styrene-isoprene block copolymer, a styrene-butadiene block copolymer, and a styrene-ethylene-butylene-styrene block copolymer; the mass of the styrene-isoprene block copolymer is 1%-15% of the total mass of the conformal paint, the mass of the styrene-butadiene block copolymer is 1%-15% of the total mass of the conformal paint, and the mass of the styrene-ethylene-butylene-styrene block copolymer is 1%-5% of the total mass of the conformal paint.

[0010] In some embodiments, the mass ratio between the styrene-isoprene block copolymer, the styrene-butadiene block copolymer, and the styrene-ethylene-butylene-styrene block copolymer is 1-10:1-10:1-3.

[0011] In some embodiments, the number average molecular weight of the styrene-isoprene block copolymer is 50,000-150,000, the number average molecular weight of the styrene-butadiene block copolymer is 55,000-150,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer is 70,000-220,000.

[0012] In some embodiments, the solvent is composed of at least one of petroleum ether, isooctane, isoheptane, and isohexane, and the mass of the solvent is 40%-80% of the total mass of the conformal coating.

[0013] In some embodiments, the solvent consists of isooctane and petroleum ether, and the mixing ratio of isooctane to petroleum ether is 5-7:3-5.

[0014] In some embodiments, the mass of the methyl silicone oil is 3%-15% of the total mass of the conformal coating, the viscosity of the methyl silicone oil is in the range of 10,000-30,000 mPas, and the volatile matter is less than 1%.

[0015] In some embodiments, the mass of the hydrogen-containing silicone oil is 0.5%-5% of the total mass of the conformal coating, the viscosity of the hydrogen-containing silicone oil is in the range of 3000-10,000 mPas, and the volatile matter is less than 1%.

[0016] In some embodiments, the conformal coating further comprises calcium carbonate, stearic acid, and UV pigment, wherein the mass of calcium carbonate is 0.5%-3% of the total mass of the conformal coating, the mass of stearic acid is 0.5%-3% of the total mass of the conformal coating, and the mass of UV pigment is 0.1%-0.5% of the total mass of the conformal coating; In some embodiments, the catalyst is a Custer catalyst, and the mass of the Custer catalyst is 0.1%-0.5% of the total mass of the conformal coating; In some embodiments, the conformal coating further includes water, and the mass of the water is 0.5%-2% of the total mass of the conformal coating.

[0017] In a second aspect, the present application also provides a method for preparing a high temperature resistant and erasable outdoor conformal coating, the method for preparing a high temperature resistant and erasable outdoor conformal coating comprises the following steps: S1. Weigh each component according to the proportion; S2. Add methyl silicone oil to the solvent and stir and disperse for 1-2h; S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 85-95°C and stirring and dispersing for 4-6h; S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and a catalyst, stirring was continued at room temperature overnight to obtain the final product.

[0018] In some embodiments, before adding methyl silicone oil to the solvent in S2, the solvent is mixed with calcium carbonate, stearic acid, and UV pigment, heated to 85-95° C., dispersed for 1-2 hours, and cooled to room temperature.

[0019] In some embodiments, in S5, the catalyst is a Custer catalyst; In some embodiments, in S5, water is added dropwise under stirring at room temperature for 1-2 h.

[0020] On the third aspect, the present application also provides a method for erasing a cured film formed by a high-temperature resistant and erasable outdoor conformal coating, wherein the cured film formed by the conformal coating is erased using a matching erasing solvent, wherein the matching erasing solvent includes n-octane and petroleum ether.

[0021] The beneficial effects that this application can achieve are: 1. This product has a low viscosity at room temperature and is suitable for a variety of coating preparation processes including spraying, brushing, pouring, dipping, and dispensing machines. At the same time, low viscosity helps to evenly coat the surface of electronic components, reducing uneven coating and dripping, helping the three-proof paint to better penetrate into the gaps and corners of electronic components, providing more comprehensive protection, and helping to reduce bubbles and pinholes in the coating, thereby improving the uniformity and protective performance of the coating; 2. This product is a one-component reactive conformal coating product. Compared with two-component conformal coating products, it does not require the addition of curing agent in proportion during the coating preparation process, which reduces the complexity of construction and allows immediate use after application. 3. This product can be cured at room temperature or by heating. It has a fast curing speed. At room temperature, it can be cured within 5 minutes, which is suitable for the process requirements of automated production lines. 4. It has good high temperature resistance. On the basis of maintaining good three-proof performance, it can work at 200℃ for a long time and can instantly withstand up to 300℃, which can provide reliable protection for electronic circuit boards under extreme temperature conditions; 5. The conformal coating product prepared by this product does not contain fluorine or other permanent compounds, meets multiple technical indicators including the IPC-CC-830 standard, and has more advantages in environmental protection; 6. This application uses a matching erasing solvent to erase the cured film formed by the three-proof paint, which has a good removal effect and no residue, and is especially suitable for precision devices such as electronic circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A physical picture of the IPC standard sample after being irradiated with 365nm UVA ultraviolet rays and coated with the triple-proof paint of Example 1 of the present application is shown; Figure 2 The actual picture of the IPC standard sample before the salt spray test after the triple-proof coating of Example 1 of the present application is applied is shown; Figure 3 The actual picture of the IPC standard sample after the salt spray test after the triple-proof paint of Example 1 of the present application is applied is shown; Figure 4 A physical picture of the IPC standard sample before the salt spray test without the conformal coating of Example 1 of the present application is shown; Figure 5 A physical picture of the IPC standard sample after the salt spray test without the conformal coating of Example 1 of the present application is shown; Figure 6 A physical picture of the waterproof test of the IPC standard sample after a portion of the present application is coated with the triple-proof paint of Example 1 is shown; Figure 7 The thermal analysis curve of the three-proof paint obtained in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0024] The term "comprising" in the specification and claims of the present application and the drawings is synonymous with "including", "containing" or "characterized by", and is inclusive or open-ended, and does not exclude additional undescribed elements or method steps. "Comprising" is a technical term used in the claim language, meaning that the elements are present, but other elements may also be added and still form a structure or method within the scope of the claim.

[0025] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance. The term "about" in this application means to include a small change (up to + / -10%) from the stated value.

[0026] In the first aspect, the present application provides a high-temperature resistant and erasable outdoor conformal paint, which includes a solvent, methyl silicone oil, hydrogenated silicone oil, a catalyst, a styrene-isoprene block copolymer, a styrene-butadiene block copolymer, and a styrene-ethylene-butylene-styrene block copolymer; the mass of the styrene-isoprene block copolymer is 1%-15% of the total mass of the conformal paint, the mass of the styrene-butadiene block copolymer is 1%-15% of the total mass of the conformal paint, and the mass of the styrene-ethylene-butylene-styrene block copolymer is 1%-5% of the total mass of the conformal paint.

[0027] Styrene-isoprene block copolymer (SIS) is a synthetic polymer material composed of styrene and isoprene monomers arranged alternately in a block structure. It has good elasticity and resilience and can return to its original shape after strain. SIS exhibits high viscosity and can provide good adhesion properties. At low temperatures, SIS can still maintain good elasticity and viscosity. It has good tolerance to some common solvents and chemicals.

[0028] Styrene-butadiene block copolymer (SBS) is a triblock copolymer with styrene and butadiene as monomers, known as the "third generation of synthetic rubber". SBS has the properties of plastic and rubber, with excellent tensile strength, large surface friction coefficient, good low temperature performance, excellent electrical properties, and good processing performance.

[0029] Styrene-ethylene-butylene-styrene block copolymer (SEBS) is a block copolymer of styrene (S)-ethylene (E) / butylene (B)-(S), which combines the thermoplastic characteristics of polystyrene and the elastomeric characteristics of ethylene-butylene copolymer in the same polymer. SEBS does not contain unsaturated double bonds, so it has good stability and aging resistance. SEBS has good UV stability, oxidation resistance and thermal stability.

[0030] It should be noted that the mass of the styrene-isoprene block copolymer is 1%-15% of the total mass of the conformal coating, and can be 1%, 3%, 5%, 8%, 10%, 12%, 15% and any value therebetween. Preferably, the mass of the styrene-isoprene block copolymer is 4% of the total mass of the conformal coating.

[0031] The mass of the styrene-butadiene block copolymer is 1%-15% of the total mass of the conformal coating, and can be 1%, 3%, 5%, 8%, 10%, 12%, 15% and any value therebetween. Preferably, the mass of the styrene-butadiene block copolymer is 4% of the total mass of the conformal coating.

[0032] The mass of the styrene-ethylene-butylene-styrene block copolymer is 1%-5% of the total mass of the conformal coating, and can be 1%, 2%, 3%, 4%, 5% and any value therebetween. Preferably, the mass of the styrene-ethylene-butylene-styrene block copolymer is 3% of the total mass of the conformal coating.

[0033] Adding a combination of three specific block copolymers in a preferred ratio is more conducive to improving the rapid curing performance and thermal stability of the final three-proof coating product.

[0034] The applicant of the present application creatively discovered a conformal coating system of methyl silicone oil + hydrogenated silicone oil + a combination of three specific block copolymers + solvent + catalyst. By adding a specific ratio of styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene-styrene block copolymer, the combination of the three block copolymers and the other ingredients work together to finally obtain a conformal coating product that can be cured within 5 minutes at room temperature and has excellent high temperature resistance. At the same time, it can also effectively prevent moisture, salt spray and chemical corrosion, and has excellent conformal coating performance.

[0035] Although the mechanism is not clear, experiments have shown that the core components of the three-conformal coating, which is a combination of silicone oil + hydrogenated silicone oil + three block copolymers + solvent + catalyst, are conducive to significantly improving the curing performance and high temperature resistance of the three-conformal coating. The possible reasons are as follows: The specifically designed structures of styrene-isoprene block copolymers, styrene-butadiene block copolymers, and styrene-ethylene-butylene-styrene block copolymers can adjust the molecular weight distribution and intermolecular forces of the polymers, thereby affecting their viscosity and curing behavior.

[0036] The introduction of styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene-styrene block copolymer can change the fluidity and molecular weight of the three-proof coating, thereby reducing the viscosity of the system. Specifically, different monomer units in the copolymer can provide different functional groups and chain segments. The introduction of these chain segments helps to interrupt the mutual entanglement between polymer chains and reduce the interaction between molecules, thereby reducing the viscosity of the overall system.

[0037] The addition of styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene-styrene block copolymer can provide additional reactive sites to promote the curing reaction. The chain segments of the copolymer of the present application can react with silicone to increase the curing speed. This synergistic effect helps the three-proof paint to achieve complete curing at room temperature without the need for additional heating or the addition of a drying agent.

[0038] The introduction of styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene-styrene block copolymer can improve the compatibility between the components in the silicone system, which is beneficial for reducing viscosity and increasing curing speed. Good compatibility can ensure the uniformity and stability of the cured film, thereby improving curing efficiency.

[0039] During the curing process of conformal coating, the steric hindrance effect caused by the increase in molecular weight will increase, which will slow down the reaction rate. By adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, the molecular structure and intermolecular forces of the polymer can be effectively adjusted, the flexibility of the chain segments can be improved and the distance between molecules can be increased, thereby reducing the steric hindrance effect, making it easier for the reactive groups to contact and react, thereby accelerating the curing speed.

[0040] The present application can introduce more specific segments through the molecular structures of specifically designed styrene-isoprene block copolymers, styrene-butadiene block copolymers, and styrene-ethylene-butylene-styrene block copolymers, which have high thermal stability, thereby improving the temperature resistance of the three-proof paint. At the same time, by increasing the cross-linking density of the copolymer in the three-proof paint, its thermal stability and mechanical strength can be improved, thereby improving the temperature resistance.

[0041] The specific ratios of styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene-styrene block copolymer in this application improve the physical and chemical properties of the three-proof paint, making the three-proof paint easier to erase after curing, which is very important for the maintenance and rework process of electronic equipment. More specifically, the addition of three specific ratios of copolymers improves the compatibility of the components of the three-proof paint, reduces the porosity of the cured film, reduces the volume shrinkage of the cured film, and increases the flexibility of the cured film. The combined effect of these characteristics makes the cured film easier to be removed as a whole. Furthermore, the addition of three specific ratios of copolymers also improves the cross-linking properties of the three-proof paint, so that it can be erased by the matching erasing solvent of this application, with good removal effect and no residue, and is particularly suitable for precision electronic circuit devices.

[0042] In some embodiments, the mass ratio of styrene-isoprene block copolymer, styrene-butadiene block copolymer and styrene-ethylene-butylene-styrene block copolymer is 1-10:1-10:1-3. Among them, the preferred mass ratio of the three is 4:4:3, but it is not limited to this. Reasonable setting of the mass ratio between styrene-isoprene block copolymer, styrene-butadiene block copolymer and styrene-ethylene-butylene-styrene block copolymer is conducive to improving the rapid curing performance and thermal stability of the final three-proof paint product. At the same time, the reasonable allocation of the three can affect the density of the cured film, thereby affecting the corrosion resistance.

[0043] In some embodiments, the number average molecular weight of the styrene-isoprene block copolymer is 50,000-150,000, which can be 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, and any value therebetween; the number average molecular weight of the styrene-butadiene block copolymer is 55,000-150,000, which can be 55,000, 60,000, 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, and any value therebetween; the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer is 70,000-220,000, which can be 70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, and any value therebetween.

[0044] Preferably, the number average molecular weight of the styrene-isoprene block copolymer is 70,000, the number average molecular weight of the styrene-butadiene block copolymer is 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer is 120,000. Reasonable setting of the number average molecular weights of the styrene-isoprene block copolymer, the styrene-butadiene block copolymer and the styrene-ethylene-butylene-styrene block copolymer can adjust the film-forming speed and coating density of the cured film, and can also improve the corrosion resistance and weather resistance of the cured film.

[0045] In some embodiments, the solvent is composed of at least one of petroleum ether, isooctane, isoheptane, and isohexane. The present application has no special requirements for the properties of the specific components as long as they can be used to dissolve polymers.

[0046] In some embodiments, the mass of the solvent is 40%-80% of the total mass of the conformal coating, and can be 40%, 50%, 60%, 70%, 80% and any value therebetween; reasonably setting the mass of the solvent can accelerate the dissolution rate of the polymer and increase production efficiency.

[0047] It should be noted that the solvent is preferably composed of isooctane and petroleum ether. The advantage of using isooctane and petroleum ether is that the storage stability of the conformal coating product can be improved.

[0048] In some embodiments, the mixing ratio of isooctane and petroleum ether is 5-7:3-5, and the mixing ratio of isooctane and petroleum ether is preferably 7:3, but is not limited thereto, and can be 5:5, 5.5:4.5, 6:4, 6.5:3.5, and any value therebetween. The advantage of setting a reasonable mixing ratio of isooctane and petroleum ether is that the storage stability of the conformal coating product can be improved.

[0049] In some embodiments, the mass of the methyl silicone oil is 3%-15% of the total mass of the conformal coating, and can be 3%, 5%, 8%, 10%, 12%, 15% and any value therebetween; the viscosity of the methyl silicone oil is in the range of 10,000-30,000 mPas, and the volatile matter is less than 1%. Reasonable selection of the mass and properties of the methyl silicone oil can further improve the heat resistance of the coating.

[0050] In some embodiments, the mass of hydrogen-containing silicone oil is 0.5%-5% of the total mass of the conformal coating, and can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% and any value therebetween; the viscosity of hydrogen-containing silicone oil ranges from 3000 to 10,000 mPas, and the volatile matter is less than 1%. Reasonable selection of the mass and properties of hydrogen-containing silicone oil can further improve the curing speed of the coating.

[0051] In some embodiments, the conformal coating further comprises calcium carbonate, stearic acid, and UV pigment, wherein the mass of calcium carbonate is 0.5%-3% of the total mass of the conformal coating, and may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3% and any value therebetween; the mass of stearic acid is 0.5%-3% of the total mass of the conformal coating, and may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3% and any value therebetween; the mass of UV pigment is 0.1%-0.5% of the total mass of the conformal coating, and may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and any value therebetween; the purpose of adding calcium carbonate and stearic acid is to increase the wear resistance of the coating, and the purpose of adding UV pigment is to facilitate the quality inspection of the coating under ultraviolet conditions.

[0052] In some embodiments, the catalyst is a Custer catalyst, and the mass of the Custer catalyst is 0.1%-0.5% of the total mass of the conformal coating, and can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and any value therebetween; It should be noted that the Custer catalyst is a preferred choice, but is not limited thereto. The present application does not particularly limit the catalyst used, and it can be a catalyst conventionally used in a three-proof paint known to those skilled in the art. Preferably, the catalyst can also be a platinum catalyst or an organic catalyst. Adding a catalyst to the three-proof paint can further accelerate the curing speed of the coating.

[0053] In some embodiments, the conformal coating further comprises water, and the mass of the water is 0.5%-2% of the total mass of the conformal coating, and can be 0.5%, 1%, 1.5%, 2% and any value therebetween. Adding water to the conformal coating can further increase the storage period of the conformal coating product.

[0054] It is understandable that calcium carbonate, stearic acid, UV pigment and water are used to optimize the storage performance, detection method or performance of the conformal coating. Even if these components are not added, it does not affect the preparation of the high temperature resistant and erasable outdoor conformal coating of the technical solution of this application by other components.

[0055] In a second aspect, the present application also provides a method for preparing a high temperature resistant and erasable outdoor conformal coating, the method for preparing a high temperature resistant and erasable outdoor conformal coating comprises the following steps: S1. Weigh each component according to the proportion; S2. Add methyl silicone oil to the solvent and stir and disperse for 1-2h; S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 85-95°C and stirring and dispersing for 4-6h; S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and a catalyst, stirring was continued at room temperature overnight to obtain the final product.

[0056] The present application has no particular restrictions on the methods of stirring and dispersing and stirring at room temperature, and a suitable stirring speed can be selected according to the specific situation.

[0057] In some embodiments, before adding methyl silicone oil to the solvent in S2, the solvent is mixed with calcium carbonate, stearic acid, and UV pigment, heated to 85-95° C. for dispersion for 1-2 hours, and cooled to room temperature. The purpose of this step is to allow calcium carbonate, stearic acid, and UV pigment functional additives to be fully mixed and dispersed with the coating matrix.

[0058] In some embodiments, in S5, the catalyst is a Custer catalyst; In some embodiments, in S5, water is added dropwise within 1-2 hours of stirring at room temperature. The purpose of this step is to further increase the storage period of the product.

[0059] The order of adding materials designed by the present application can improve production efficiency and reduce production costs.

[0060] On the third aspect, the present application also provides a method for erasing a cured film formed by a high-temperature resistant and erasable outdoor conformal paint, wherein a matching erasing solvent is used to erase the cured film formed by the conformal paint, wherein the matching erasing solvent includes n-octane and petroleum ether. The matching erasing solvent of the present application can remove the conformal paint more quickly, leaving no residue after erasure, and can effectively improve the cleaning efficiency, especially when large-scale cleaning or rework is required, this method can save time and cost; the removal effect is good and there is no residue, which is especially suitable for precision devices such as electronic circuits.

[0061] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0062] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0063] The conformal coatings in Examples 1-12 and Comparative Examples 1-5 were prepared according to the formula listed in Table 1.

[0064] Table 1

[0065] The manufacturers and purity of the component reagents used in the examples and comparative examples of the present application are as follows. It should be noted that the following content does not limit the protection scope of the present application, but is only an exemplary description: The solvent consisted of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether was 7:3, wherein isooctane and petroleum ether were (Sinopharm Reagent Chemical Co., Ltd., analytical grade); Calcium carbonate (Sinopharm Reagent Chemical Co., Ltd., chemically pure); Stearic acid (Sinopharm Reagent Chemical Co., Ltd., chemically pure); UV pigment (Shanghai Jingyan Chemical Co., Ltd., industrial grade); Methyl silicone oil (Zhonghao Chenguang Chemical Research Institute Co., Ltd., chemically pure); Styrene-isoprene block copolymer (Zhonghao Chenguang Chemical Research Institute Co., Ltd., industrial grade); Styrene-butadiene block copolymer (Zhonghao Chenguang Chemical Research Institute Co., Ltd., industrial grade); Styrene-ethylene-butylene-styrene block copolymer (Zhonghao Chenguang Chemical Research Institute Co., Ltd., industrial grade); Hydrogenated silicone oil (Zhonghao Chenguang Chemical Research Institute Co., Ltd., industrial grade); The catalyst is a Custer catalyst, wherein the Custer catalyst (Guangzhou Xiupu Chemical Co., Ltd., industrial grade); Water (Sinopharm Reagent Chemical Co., Ltd., purified water).

[0066] Example 1 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 68.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0067] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0068] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0069] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0070] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0071] Example 2 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 71.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 1% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0072] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0073] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0074] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0075] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0076] Example 3 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 64.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 8% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0077] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0078] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0079] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0080] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0081] Example 4 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 57.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 15% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0082] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0083] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0084] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0085] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0086] Example 5 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 71.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 1% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0087] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0088] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0089] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0090] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0091] Example 6 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 64.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 8% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0092] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0093] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0094] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0095] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0096] Example 7 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 57.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 15% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0097] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0098] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0099] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0100] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0101] Example 8 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 70.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 1% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0102] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0103] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0104] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0105] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0106] Example 9 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 66.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 5% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0107] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0108] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0109] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0110] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0111] Example 10 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 68.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0112] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0113] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer is 120,000, the number average molecular weight of the styrene-butadiene block copolymer is 120,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer is 200,000; S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0114] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0115] Embodiment 11 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 69.9% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 0.5% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0116] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0117] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0118] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0119] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0120] Example 12 A high-temperature resistant and erasable outdoor conformal paint, which comprises, based on the total mass of the conformal paint being 100%, 65.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 5% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0121] The preparation method of the above-mentioned conformal coating comprises the following specific steps: S1. Weigh each component according to the proportion; S2. Mix the solvent with calcium carbonate, stearic acid and UV pigment, heat to 95°C and disperse for 1 hour, cool to room temperature, then add methyl silicone oil and stir and disperse for 1 hour; The solvent is composed of isooctane and petroleum ether, and the mixing ratio of isooctane and petroleum ether is 7:3; The viscosity range of methyl silicone oil is 10,000 mPas and the volatile matter is less than 0.6%.

[0122] S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 95°C and stirring and dispersing for 6h; Among them, the number average molecular weight of the styrene-isoprene block copolymer was 70,000, the number average molecular weight of the styrene-butadiene block copolymer was 80,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer was 120,000.

[0123] S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and Custer catalyst, stir at room temperature overnight, and add water dropwise within 2 hours of stirring at room temperature to obtain the final product.

[0124] Among them, the viscosity range of hydrogen-containing silicone oil is 10,000 millipascals, and the volatile matter is less than 0.6%.

[0125] Comparative Example 1 A conformal coating, based on 100% of the total mass of the conformal coating, comprises 72.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-butadiene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst and 2% of water.

[0126] The preparation method is the same as that in Example 1, except that: in Comparative Example 1, no styrene-isoprene block copolymer is added, and the missing mass is made up by the solvent.

[0127] Comparative Example 2 A conformal coating, based on 100% of the total mass of the conformal coating, comprises 72.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 3% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst and 2% of water.

[0128] The preparation method is the same as that in Example 1, except that: in Comparative Example 2, no styrene-butadiene block copolymer is added, and the missing mass is made up by the solvent.

[0129] Comparative Example 3 A conformal coating, based on 100% of the total mass of the conformal coating, comprises 71.4% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 4% of a styrene-isoprene block copolymer, 4% of a styrene-butadiene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst and 2% of water.

[0130] The preparation method is the same as that in Example 1, except that: in Comparative Example 3, no styrene-ethylene-butylene-styrene block copolymer is added, and the missing mass is made up by the solvent.

[0131] Comparative Example 4 A conformal coating, based on the total mass of the conformal coating being 100%, comprises 19.4% solvent, 0.5% calcium carbonate, 0.5% stearic acid, 0.1% UV pigment, 15% methyl silicone oil, 20% styrene-isoprene block copolymer, 20% styrene-butadiene block copolymer, 20% styrene-ethylene-butylene-styrene block copolymer, 2% hydrogenated silicone oil, 0.5% catalyst and 2% water.

[0132] The preparation method is similar to that in Example 1.

[0133] Comparative Example 5 A conformal coating, based on 100% of the total mass of the conformal coating, comprises 77.9% of a solvent, 0.5% of calcium carbonate, 0.5% of stearic acid, 0.1% of a UV pigment, 15% of methyl silicone oil, 0.5% of a styrene-isoprene block copolymer, 0.5% of a styrene-butadiene block copolymer, 0.5% of a styrene-ethylene-butylene-styrene block copolymer, 2% of a hydrogenated silicone oil, 0.5% of a catalyst, and 2% of water.

[0134] The preparation method is similar to that in Example 1.

[0135] Test Case In order to verify the performance of the product of the present application, the three-proof coatings prepared in Examples 1-12 and Comparative Examples 1-5 were respectively subjected to relevant performance tests. The specific test results are shown in Tables 2 and 3. The specific test methods in Tables 2 and 3 are as follows: Viscosity: coating-4 cup method, test temperature 25℃, relative humidity 55%; Complete curing time: The test temperature is 25℃ and the relative humidity is 55%. Spray the conformal coating on the glass test piece and start timing immediately. The timing ends when the conformal coating changes from transparent to white translucent. At the same time, the glass test piece is completely immersed below the water surface. If the surface of the cured film is cured without flow, the recorded time is the complete curing time. Working temperature: hot table 200℃ test; Initial decomposition temperature: For detection method, refer to GB / T27761-2011; Salt spray resistance: refer to GB / T1771-2007 for the test method; Water contact angle: See GB / T30693-2014 for the test method; 10h@200℃ apparent state after treatment: visual inspection, visual inspection after 365nmUVA ultraviolet irradiation; Use n-octane and petroleum ether to erase: After 10h@200℃ treatment, erase the cured film to check whether there is any n-octane and petroleum ether residue, and check whether the circuit board is damaged.

[0136] Table 2 Uncured properties of products of Examples 1-12 and Comparative Examples 1-5

[0137] Table 3 Performance of products of Examples 1-12 and Comparative Examples 1-5 after curing

[0138] It can be seen from the results of Table 2 and Table 3 that, relative to the comparative example, by adopting the embodiment of the present invention, by adding a specific ratio of styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene-styrene block copolymer, the combination of the three block copolymers and the other ingredients work together to obtain a conformal coating product that has significantly shorter complete curing time, higher working temperature, initial decomposition temperature, better salt spray resistance and hydrophobicity.

[0139] At the same time, it can be seen that the conformal coating in the comparative example has poor heat resistance. After 10h@200℃ treatment, the surface state of the cured film turned yellow. It is speculated that some kind of pyrolysis or oxidation reaction may have occurred, which will seriously affect the subsequent performance. Further, based on the erasing performance using n-octane and petroleum ether, it is speculated that the degree of cross-linking of the cured film has changed during the heat treatment process, resulting in the inability to completely erase the cured film formed by the conformal coating using n-octane and petroleum ether. At the same time, it was found that the circuit board had some damage after removing the cured film, proving that the conformal coating in the comparative example cannot protect the circuit board at high temperatures.

[0140] Furthermore, the conformal coating using the technical solution of the present application can still be wiped off by the erasing solvent provided with the present application even after high-temperature treatment, which proves that the present application has excellent high-temperature resistance. It also proves that the erasing method of the present application can still be used to wipe it off even in harsh operating environments.

[0141] Furthermore, according to Examples 1-12, it can be seen that by adopting the preferred scheme of the present invention, a one-component conformal coating product with higher operating temperature, faster curing speed, stronger protective ability and the like can be obtained.

[0142] The following is a product diagram to illustrate the technical effect of the technical solution of the present application. The conformal coating obtained in Example 1 was coated on an IPC standard sample to form a cured film, and then tested.

[0143] like Figure 1 As shown, Figure 1 This is a physical picture of the IPC standard sample after being coated with the triple-proof paint of Example 1 under 365nm UVA ultraviolet radiation.

[0144] like Figure 2 As shown, Figure 2 This is a photo of the IPC standard sample before the salt spray test after coating the three-proof paint of Example 1. Figure 3 As shown, Figure 3 This is a real picture of the IPC standard sample after the salt spray test after the three-proof paint of Example 1 is applied. It can be seen that the cured film formed by the three-proof paint of Example 1 of the present application has strong salt spray resistance, and the appearance before and after the salt spray test is basically unchanged.

[0145] like Figure 4 As shown, Figure 4 This is a photo of the IPC standard sample before the salt spray test without the three-proof coating of Example 1. Figure 5 As shown, Figure 5 This is a photo of the IPC standard sample after the salt spray test without the conformal coating of Example 1. It can be seen that if the conformal coating is not applied, the bare copper wire on the IPC standard sample is severely corroded.

[0146] like Figure 6 As shown, Figure 6 The upper part of the device is coated with the conformal coating of Example 1. Figure 6 The lower part of the glass is not coated with the conformal coating of Example 1. It can be seen that Figure 6 A clear hydrophobic coating boundary line is shown in the figure, proving that the conformal coating of Example 1 of the present application has good hydrophobic properties.

[0147] like Figure 7 As shown, Figure 7 This is a thermal analysis curve of the conformal coating obtained in Example 1 of the present application. It can be seen that the epitaxial starting temperature Te of the conformal coating of the present application is 360.7°C. The conformal coating of the present application can work at 200°C for a long time and can instantly reach 300°C. It can provide reliable protection for electronic circuit boards under extreme temperature conditions and has good high temperature resistance.

[0148] The present application also provides a method for erasing a cured film formed by a high-temperature resistant and erasable outdoor conformal coating, wherein a matching erasing solvent is used to erase the cured film formed by the conformal coating, and the conformal coating prepared in Example 1 of the present application is coated on two IPC standard circuit boards respectively, and waited for curing to form a cured film. The erasing method of the present application and the prior art are used to erase and compare the cured films on the two standard circuit boards, and the results are shown in Table 4.

[0149] Table 4

[0150] From the above results, it can be seen that the use of the erasing solvent of the present application to erase the cured film formed by the three-proof paint has a good removal effect without residue, and it is proved that the erasing solvent will not cause damage to the circuit board itself, and is particularly suitable for precision devices such as electronic circuits.

[0151] The embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A high temperature resistant and erasable outdoor conformal paint, characterized in that: The high-temperature resistant and erasable outdoor conformal paint includes solvent, methyl silicone oil, hydrogenated silicone oil, catalyst, styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene-styrene block copolymer; wherein the mass of styrene-isoprene block copolymer is 1%-15% of the total mass of the conformal paint, the mass of styrene-butadiene block copolymer is 1%-15% of the total mass of the conformal paint, and the mass of styrene-ethylene-butylene-styrene block copolymer is 1%-5% of the total mass of the conformal paint.

2. The high temperature resistant and erasable outdoor conformal coating according to claim 1, characterized in that: The mass ratio of the styrene-isoprene block copolymer, the styrene-butadiene block copolymer and the styrene-ethylene-butylene-styrene block copolymer is 1-10:1-10:1-3.

3. The high temperature resistant and erasable outdoor conformal coating according to claim 1, characterized in that: The number average molecular weight of the styrene-isoprene block copolymer is 50,000-150,000, the number average molecular weight of the styrene-butadiene block copolymer is 55,000-150,000, and the number average molecular weight of the styrene-ethylene-butylene-styrene block copolymer is 70,000-220,000.

4. The high temperature resistant and erasable outdoor conformal coating according to claim 1, characterized in that: The solvent is selected from one or more of petroleum ether, isooctane, isoheptane, and isohexane, and the mass of the solvent is 40%-80% of the total mass of the conformal coating.

5. The high temperature resistant and erasable outdoor conformal coating according to claim 4, characterized in that: The solvent consists of isooctane and petroleum ether, and the mixing ratio of the isooctane to the petroleum ether is 5-7:3-5.

6. The high temperature resistant and erasable outdoor conformal coating according to claim 1, characterized in that: The mass of the methyl silicone oil is 3%-15% of the total mass of the three-proof paint, the viscosity range of the methyl silicone oil is 10,000-30,000 mPas, and the volatile matter is less than 1%.

7. The high temperature resistant and erasable outdoor conformal coating according to claim 1, characterized in that: The mass of the hydrogen-containing silicone oil is 0.5%-5% of the total mass of the three-proof paint, the viscosity of the hydrogen-containing silicone oil is in the range of 3000-10,000 milliPascals, and the volatile matter is less than 1%.

8. The high temperature resistant and erasable outdoor conformal coating according to claim 1, characterized in that: The conformal coating further comprises calcium carbonate, stearic acid, and UV pigment, wherein the mass of the calcium carbonate is 0.5%-3% of the total mass of the conformal coating, the mass of the stearic acid is 0.5%-3% of the total mass of the conformal coating, and the mass of the UV pigment is 0.1%-0.5% of the total mass of the conformal coating; and / or, The catalyst is a Custer catalyst, and the mass of the Custer catalyst is 0.1%-0.5% of the total mass of the conformal coating; and / or, The conformal coating also includes water, and the mass of the water is 0.5%-2% of the total mass of the conformal coating.

9. A method for preparing a high temperature resistant and erasable outdoor conformal coating, the method being used to prepare the high temperature resistant and erasable outdoor conformal coating as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Weigh each component according to the proportion; S2. Add methyl silicone oil to the solvent and stir and disperse for 1-2h; S3, after adding styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, heating to 85-95°C and stirring and dispersing for 4-6h; S4, cooling to room temperature; S5. After adding hydrogen-containing silicone oil and a catalyst, stirring was continued at room temperature overnight to obtain the final product.

10. The preparation method according to claim 9, characterized in that: In S2, before adding methyl silicone oil to the solvent, the solvent is mixed with calcium carbonate, stearic acid and UV pigment, heated to 85-95°C for dispersion for 1-2 hours and cooled to room temperature.

11. The preparation method according to claim 9, characterized in that: In S5, the catalyst is a Custer catalyst; and / or, In S5, water was added dropwise with stirring at room temperature for 1-2 h.

12. A method for erasing a cured film formed by the high temperature resistant erasable outdoor conformal paint according to any one of claims 1 to 8, characterized in that: A matching wiping solvent is used to wipe off the cured film formed by the three-proof paint, wherein the matching wiping solvent contains n-octane and petroleum ether.

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