Moisture-proof curing agent applied to PCB (printed circuit board) coating and preparation process of moisture-proof curing agent

Abstract

The invention discloses a moisture-proof curing agent applied to a PCB (Printed Circuit Board) coating and a preparation process of the moisture-proof curing agent, and relates to the technical field of PCB protective materials. The invention discloses a moisture-proof curing agent applied to a PCB coating. The invention discloses a nano-silicon dioxide modified epoxy resin, which is prepared from the following raw materials in parts by weight: 30 to 50 parts of epoxy resin, 20 to 35 parts of polyurethane prepolymer, 10 to 15 parts of nano-silicon dioxide, 5 to 10 parts of methyltrimethoxysilane, 3 to 8 parts of gamma-aminopropyltriethoxysilane, 0.5 to 2 parts of dibutyltin dilaurate, 2 to 5 parts of 2-hydroxy-4 '-(2-hydroxyethoxy)-2-methyl propiophenone and 1 to 3 parts of antioxidant 1076. The self-repairing coating is prepared from, by weight, 20-30 parts of epoxy resin, 8-12 parts of tripropylene glycol diacrylate, 5-8 parts of polytetrafluoroethylene micro powder, 4-7 parts of self-repairing microcapsules and 20-30 parts of modified acrylic resin. The moisture-proof curing agent has the advantages of good moisture-proof performance, low water absorption, excellent mechanical properties such as hardness and adhesive force, good temperature resistance and impact resistance, self-repairing function, high repairing efficiency, strong weatherability, no obvious change after ultraviolet aging, and excellent performance in all aspects, and is suitable for PCB coating protection.

Description

Technical Field

[0001] This invention relates to the field of PCB circuit board protective materials technology, specifically to a moisture-proof curing agent for PCB circuit board coatings and its preparation process. Background Technology

[0002] In today's rapidly developing electronic information technology landscape, PCBs, as core components of electronic devices, are crucial for their performance and reliability. With the widespread adoption of technologies such as 5G communication, artificial intelligence, and the Internet of Things, PCBs are evolving towards higher density, miniaturization, and multi-functionality, placing higher demands on their protective materials. However, PCBs often face challenges in humid environments, such as high-humidity workshops in industrial production, rainy weather encountered by outdoor equipment, and condensation caused by temperature differences during electronic product use. Humid environments can not only lead to a decrease in the surface insulation resistance of the PCB, causing electrical faults such as short circuits and leakage, but also accelerate the electrochemical corrosion of component leads and solder joints, resulting in poor contact or abnormal signal transmission, significantly reducing the lifespan and operational stability of the equipment.

[0003] Currently, while moisture-proof materials for PCB circuit board coatings have some applications in the market, they still have many shortcomings. Some traditional moisture-proof curing agents use a single resin as a base, such as pure epoxy resin or acrylic resin. Due to molecular structure limitations, the density of the moisture barrier is insufficient. After prolonged use in humid environments, water molecules can easily penetrate through the coating pores, leading to a significant decrease in protective performance. Some materials sacrifice mechanical properties in pursuit of moisture-proof effects, resulting in insufficient hardness and impact resistance. During the transportation, vibration, and installation / removal of PCB circuit boards, the coating is prone to cracking and peeling. Furthermore, most existing moisture-proof materials lack self-healing capabilities. When the coating develops micro-cracks or pinholes due to mechanical stress or thermal expansion and contraction, it cannot repair the damaged areas itself. Moisture will further penetrate along the defects, creating a vicious cycle and affecting the overall protective effect. Moreover, some materials have poor weather resistance. Under the long-term effects of external factors such as ultraviolet radiation and ozone, the coating is prone to yellowing, chalking, and embrittlement, leading to unstable performance and failing to meet the protection requirements of outdoor electronic equipment or equipment in long-term service. Therefore, developing a PCB circuit board coating moisture-proof curing agent that combines excellent moisture resistance, mechanical properties, self-healing function, and weather resistance is of great practical significance for improving the environmental adaptability and reliability of electronic equipment. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a moisture-proof curing agent for PCB circuit board coatings and its preparation process, solving the problems of insufficient moisture barrier density, poor mechanical properties, lack of self-healing function, and poor weather resistance of traditional moisture-proof curing agents.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A moisture-proof curing agent for PCB circuit board coatings comprises the following raw materials in parts by weight: 30-50 parts epoxy resin, 20-35 parts polyurethane prepolymer, 10-15 parts nano silica, 5-10 parts methyltrimethoxysilane, 3-8 parts γ-aminopropyltriethoxysilane, 0.5-2 parts dibutyltin dilaurate, 2-5 parts 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 1-3 parts antioxidant 1076, 8-12 parts tripropylene glycol diacrylate, 5-8 parts polytetrafluoroethylene micropowder, 4-7 parts self-healing microcapsules, and 20-30 parts modified acrylic resin.

[0006] Furthermore, the epoxy resin is one of bisphenol A type epoxy resin and bisphenol F type epoxy resin; the nano silica particles have a particle size of 10-50 nm and have undergone surface modification treatment with a silane coupling agent.

[0007] Furthermore, the polyurethane prepolymer is prepared from hexamethylene diisocyanate and polytetrahydrofuran diol, wherein the number-average molecular weight of the polytetrahydrofuran diol is 1500.

[0008] Furthermore, the modified acrylic resin is prepared using the following specific steps: A1. Place anatase nano-titanium dioxide into a plasma reaction chamber, introduce a mixture of oxygen and argon gas with a volume ratio of 1:3, and remove it after 10 minutes. Prepare a composite coupling agent by combining silane coupling agent KH-570 with nano-silver particles. Add acrylic resin to the reaction vessel, heat to 85℃ to melt, and add the treated nano-titanium dioxide, composite coupling agent, and glycidyl methacrylate in sequence under stirring at 200 r / min. Disperse ultrasonically for 2.5 h, and irradiate with 365 nm ultraviolet light for 30 minutes before the end of the reaction. After the reaction is completed, cool to room temperature. A2. Carbon nanotubes and sodium dodecylbenzenesulfonate were added to N-methylpyrrolidone and sonicated for 1.5 h to obtain a carbon nanotube dispersion. Graphene oxide, N-isopropylacrylamide, and ammonium persulfate were taken and stirred at 55℃ for 300 r / min for 5 h to generate a thermosensitive graphene composite material. The first modified resin was heated to 65℃, and carbon nanotube dispersion and dibutyltin dilaurate were added dropwise under nitrogen protection. The temperature was raised to 105℃, and the thermosensitive graphene composite material was added. The mixture was stirred at 300 r / min for 3.5 h under 8 MPa pressure. A3. Dithiodipropionic acid and trimethylolpropane were added to a three-necked flask, followed by p-toluenesulfonic acid. The mixture was stirred at 200 rpm for 9 hours at 125°C. Then, 2-aminoethanethiol was added, and the mixture was reacted at 80°C for 4 hours to obtain a hyperbranched polyester containing disulfide bonds. The modified resin was heated to 125°C, and light stabilizer 770 was added. The mixture was stirred at 200 rpm for 15 minutes. The hyperbranched polyester containing disulfide bonds was slowly added, and ozone at a concentration of 15 ppm was introduced. The mixture was stirred at 300 rpm for 4.5 hours. After the reaction was completed, microencapsulated benzoyl peroxide was added, and the mixture was stirred for 30 minutes until it was uniformly dispersed.

[0009] Furthermore, the silane coupling agent KH-570 in A1 is combined with silver nanoparticles to form a composite coupling agent, and the specific method is as follows: The silane coupling agent KH-570 and nano-silver particles were added to anhydrous ethanol, followed by the addition of 3-mercaptopropionic acid. The mixture was then shaken at 300 r / min for 15 min under a constant temperature water bath at 30℃, with a shaking frequency of 50 Hz, while simultaneously introducing a 5% H2 / Ar mixed gas. After mixing, the mixture was dried in a vacuum drying oven at 60℃ for 2 h, and then annealed at 120℃ under a nitrogen atmosphere for 1 h to obtain a uniformly dispersed composite coupling agent.

[0010] Furthermore, the ratio of silane coupling agent KH-570, nano-silver particles, anhydrous ethanol, and 3-mercaptopropionic acid in the composite coupling agent is 7g:0.8g:35g:0.5g; the flow rate of the mixed gas is 20mL / min; the nano-silver particles have a particle size of 5-10nm, and their surface is modified with sodium citrate, with a zeta potential of -30mV to -40mV.

[0011] Furthermore, in A1, the ratio of acrylic resin, nano titanium dioxide, composite coupling agent, and glycidyl methacrylate is 100g:20g:7.8g:4g; the ratio of silane coupling agent KH-570 and nano silver particles is 7g:0.8g.

[0012] Furthermore, in A2, the ratio of carbon nanotubes, sodium dodecylbenzenesulfonate, and N-methylpyrrolidone is 12g:4g:100g; the ratio of graphene oxide, N-isopropylacrylamide, and ammonium persulfate is 5g:10g:0.5g; the ratio of the first modified resin and dibutyltin dilaurate is 130g:2.5g; and the nitrogen flow rate is 50mL / min.

[0013] Furthermore, the ratio of dithiodipropionic acid, trimethylolpropane, p-toluenesulfonic acid, and 2-aminoethanethiol in A3 is 10g:4.2g:0.5g:2.5g; the ratio of the second modified resin, light stabilizer 770, and microencapsulated benzoyl peroxide is 130g:0.2g:1.5g.

[0014] Anatase nano-titanium dioxide, after plasma treatment, exhibits increased surface hydroxyl and unsaturated bonds, enhancing its activity. It forms a composite coupling agent with silane coupling agent KH-570 and nano-silver particles, grafting onto acrylic resin via silicon-oxygen bonds. The nano-silver particles embed into the resin network, strengthening interfacial bonding and antibacterial properties. Glycidyl methacrylate, under ultrasonic dispersion and 365nm UV irradiation, undergoes a cross-linking reaction with the resin, forming a branched structure that improves hardness and solvent resistance. Carbon nanotubes, dispersed with sodium dodecylbenzenesulfonate, are introduced to enhance the resin's tensile strength and impact resistance through a one-dimensional network. Thermosensitive graphene composites, embedded in resin under 8MPa pressure, impart temperature responsiveness and enhance environmental adaptability. Hyperbranched polyester containing disulfide bonds undergoes ozone-induced cross-linking; the dynamic breaking and recombination characteristics of disulfide bonds endow the resin with self-healing potential. Light stabilizer 770 captures UV free radicals, delaying aging.

[0015] Furthermore, the self-healing microcapsules are prepared using the following specific steps: B1. Dicyclopentadiene (core material) and urea-formaldehyde resin (wall material) were added to a three-necked flask, followed by polyethylene glycol octylphenyl ether and deionized water. The mixture was emulsified at 12,000 rpm for 12 minutes in a high-speed shear emulsifier. The pH of the system was adjusted to 4, and the temperature was raised to 45°C. A 37% formaldehyde solution was added dropwise while stirring at 350 rpm. After the addition was complete, the reaction was continued for 2.5 hours. Melamine-formaldehyde resin was then added, and the reaction was continued at 55°C with stirring for 1.5 hours. Finally, nano-silica particles were added, and the mixture was stirred at 200 rpm for 10 minutes. B2. Mix silane coupling agent KH-550 with hydroxyethyl methacrylate and dissolve in an ethanol-water solution with a volume ratio of 9:1. Add dibutyltin dilaurate to prepare a functionalized solution. Add the first modified microcapsules to the functionalized solution, sonicate for 45 min, then add Fe3O4 magnetic nanoparticles, filter and separate, wash with deionized water, and vacuum dry at 65℃ for 9 h to obtain surface-functionalized microcapsules. B3. Nanocellulose and chitosan were mixed and dissolved in 1% acetic acid solution. The mixture was ultrasonically dispersed for 15 min to form a uniform composite solution. The pH of the solution was adjusted to 5.5, calcium chloride was added, and the mixture was stirred at 200 r / min for 35 min. Then, the second modified microcapsules were added and stirred for 1.5 h. Subsequently, the mixture was treated by spray drying, with the inlet temperature controlled at 125℃ and the outlet temperature at 75℃, to form microcapsule-biopolymer composite particles. Finally, the composite particles were immersed in a phosphate buffer solution of 1.5 mg / mL glucose oxidase and reacted at 35℃ for 36 h to immobilize the enzyme on the particle surface.

[0016] Furthermore, the ratio of dicyclopentadiene, urea-formaldehyde resin, polyethylene glycol octylphenyl ether, deionized water, formaldehyde solution, melamine-formaldehyde resin, and nano-silica particles in B1 is 10g:20g:0.75g:80g:12g:1.25g:0.4g.

[0017] Furthermore, the ratio of silane coupling agent KH-550 to hydroxyethyl methacrylate, ethanol-water solution, dibutyltin dilaurate, and Fe3O4 magnetic nanoparticles in B2 is 3g:1.5g:400mL:0.2g:1.5g.

[0018] Furthermore, the ratio of nanocellulose, chitosan, acetic acid solution, calcium chloride, and glucose oxidase phosphate buffer solution in B3 is 6g:1.5g:100mL:0.8g:100mL.

[0019] Using dicyclopentadiene as the core material and urea-formaldehyde resin as the wall material, the microcapsules are encapsulated through high-speed emulsification and cross-linking with formaldehyde. Polyethylene glycol octylphenyl ether improves emulsification stability, while melamine-formaldehyde resin and nano-silica enhance the density of the wall material, ensuring stable storage of the repair agent. Silane coupling agent KH-550 and hydroxyethyl methacrylate are grafted onto the surface of the microcapsules in an ethanol-water system, forming double-bond active sites. Fe3O4 magnetic nanoparticles are adsorbed onto the surface through coordination, imparting magnetic responsiveness and facilitating dispersion and targeted repair. Nanocellulose and chitosan form a composite film in acetic acid solution to encapsulate the microcapsules, and calcium chloride cross-linking enhances mechanical strength. After glucose oxidase is fixed on the surface, when the coating is damaged, the microcapsules rupture, releasing dicyclopentadiene. The enzyme catalyzes its ring-opening polymerization, forming polymer patches at the cracks, thus achieving repair.

[0020] A method for preparing a moisture-proof curing agent for use in PCB circuit board coatings specifically includes the following steps: S1. Add epoxy resin, polyurethane prepolymer and tripropylene glycol diacrylate into the reactor, heat to 60℃, and stir at 300r / min for 20min. S2. While maintaining the stirring state, add nano silica, methyltrimethoxysilane, γ-aminopropyltriethoxysilane, and dibutyltin dilaurate in sequence. Stir for 5 minutes after each addition of raw material, and continue stirring at 300 r / min for 30 minutes after all raw materials have been added. S3. Reduce the temperature of the reactor to 40°C, and add 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, antioxidant 1076, polytetrafluoroethylene micro powder, and modified acrylic resin in sequence. Stir at 400 r / min for 1.5 h. S4. Finally, add the self-healing microcapsules and stir at 250 rpm for 30 minutes to obtain the moisture-proof curing agent.

[0021] This invention provides a moisture-proof curing agent for PCB circuit board coatings and its preparation process, which has the following beneficial effects: 1. Through the synergistic film-forming mechanism of epoxy resin and modified acrylic resin, combined with the layered barrier structure of nano-silica and the interfacial sealing effect of silane coupling agent, the coating forms a dense, non-porous three-dimensional network, effectively blocking the penetration path of water molecules. Even in long-term service in high humidity environments, it can maintain stable insulation performance, building a long-lasting moisture barrier for PCB circuit boards.

[0022] 2. The polyurethane prepolymer and tripropylene glycol diacrylate form an interpenetrating network skeleton through a cross-linking reaction. Polytetrafluoroethylene micropowder is uniformly dispersed in the system, providing toughening properties and giving the coating both a Shore hardness of over 70D and excellent impact toughness. Simultaneously, γ-aminopropyltriethoxysilane enhances the adhesion between the coating and the circuit board surface through chemical bonding, enabling it to withstand repeated bending, vibration, and other mechanical stresses, thus preventing coating peeling during transportation and installation.

[0023] 3. The self-healing microcapsules use dicyclopentadiene as the core material and are encapsulated in the coating through multiple layers of wall material. When the coating develops microcracks due to mechanical damage or thermal stress, the microcapsules rupture and release the repair agent, which polymerizes in situ under the catalysis of glucose oxidase, actively filling the crack defects. This repair process does not require external energy triggering and can restore more than 90% of the coating's mechanical and moisture-proof properties within 24 hours, significantly extending the service life of the PCB circuit board.

[0024] 4. The modified acrylic resin, by introducing disulfide bond hyperbranched polyester and light stabilizer 770, constructs a dual weather resistance mechanism of "free radical capture-dynamic bond repair". The composite addition of nano-silver particles and carbon nanotubes further enhances the resistance to ultraviolet aging and oxidation, making it suitable for long-term protection in harsh environments such as outdoor and industrial settings. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: Preparation of a moisture-proof curing agent for use in PCB circuit board coatings. The specific preparation steps are as follows: S1. Add 30 parts of bisphenol A epoxy resin, 20 parts of polyurethane prepolymer and 8 parts of tripropylene glycol diacrylate into the reactor, heat to 60°C and stir at 300 r / min for 20 min. S2. While maintaining stirring, add 10 parts of nano silica, 5 parts of methyltrimethoxysilane, 3 parts of γ-aminopropyltriethoxysilane, and 0.5 parts of dibutyltin dilaurate in sequence. Stir for 5 minutes after each addition of raw material, and continue stirring at 300 r / min for 30 minutes after all raw materials have been added. S3. Reduce the temperature of the reactor to 40°C, and add 2 parts of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 1 part of antioxidant 1076, 5 parts of polytetrafluoroethylene micro powder, and 20 parts of modified acrylic resin in sequence. Stir at 400 r / min for 1.5 h. S4. Finally, add 4 parts of self-healing microcapsules and stir at 250 r / min for 30 min to obtain a moisture-proof curing agent.

[0027] Example 2: Preparation of a moisture-proof curing agent for use in PCB circuit board coatings. The specific preparation steps are as follows: S1. Add 50 parts of bisphenol F type epoxy resin, 35 parts of polyurethane prepolymer and 12 parts of tripropylene glycol diacrylate into the reactor, heat to 60°C and stir at 300 r / min for 20 min. S2. While maintaining the stirring state, add 15 parts of nano silica, 10 parts of methyltrimethoxysilane, 8 parts of γ-aminopropyltriethoxysilane, and 2 parts of dibutyltin dilaurate in sequence. Stir for 5 minutes after each addition of raw material, and continue stirring at 300 r / min for 30 minutes after all raw materials have been added. S3. Reduce the temperature of the reactor to 40°C, and add 5 parts of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 3 parts of antioxidant 1076, 8 parts of polytetrafluoroethylene micro powder, and 30 parts of modified acrylic resin in sequence. Stir at 400 r / min for 1.5 h. S4. Finally, add 7 parts of self-healing microcapsules and stir at 250 r / min for 30 min to obtain a moisture-proof curing agent.

[0028] Example 3: Preparation of a moisture-proof curing agent for use in PCB circuit board coatings. The specific preparation steps are as follows: S1. Add 40 parts of bisphenol A epoxy resin, 25 parts of polyurethane prepolymer and 10 parts of tripropylene glycol diacrylate into the reactor, heat to 60°C and stir at 300 r / min for 20 min. S2. While maintaining stirring, add 12 parts of nano silica, 7 parts of methyltrimethoxysilane, 5 parts of γ-aminopropyltriethoxysilane, and 1 part of dibutyltin dilaurate in sequence. Stir for 5 minutes after each addition of raw material, and continue stirring at 300 r / min for 30 minutes after all raw materials have been added. S3. Reduce the temperature of the reactor to 40°C, and add 3 parts of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2 parts of antioxidant 1076, 6 parts of polytetrafluoroethylene micro powder, and 25 parts of modified acrylic resin in sequence. Stir at 400 r / min for 1.5 h. S4. Finally, add 5 parts of self-healing microcapsules and stir at 250 r / min for 30 min to obtain a moisture-proof curing agent.

[0029] Example 4: Preparation of modified acrylic resin. The specific preparation steps are as follows: A1. Place 20g of anatase nano-titanium dioxide into a plasma reaction chamber, introduce a mixture of oxygen and argon gas with a volume ratio of 1:3, and remove after 10 min. Take 7g of silane coupling agent KH-570 and 0.8g of nano-silver particles to prepare a composite coupling agent. Add 100g of acrylic resin to the reaction vessel, heat to 85℃ to melt, stir at 200r / min, and add the treated 20g of nano-titanium dioxide, 7.8g of composite coupling agent and 4g of glycidyl methacrylate in sequence. Disperse ultrasonically for 2.5h, irradiate with 365nm ultraviolet light for 30min before the end of the reaction, and cool to room temperature after the reaction is completed. A2. 12g of carbon nanotubes and 4g of sodium dodecylbenzenesulfonate were added to 100g of N-methylpyrrolidone and sonicated for 1.5h to obtain a carbon nanotube dispersion. 5g of graphene oxide, 10g of N-isopropylacrylamide and 0.5g of ammonium persulfate were taken and stirred at 300r / min at 55℃ for 5h to generate a thermosensitive graphene composite material. 130g of the first modified resin was heated to 65℃, and nitrogen gas was introduced at a flow rate of 50mL / min. Under nitrogen protection, the carbon nanotube dispersion and 2.5g of dibutyltin dilaurate were added dropwise. The temperature was raised to 105℃, and the thermosensitive graphene composite material was added. The mixture was stirred at 8MPa for 3.5h. A3. Add 10g of dithiodipropionic acid and 4.2g of trimethylolpropane to a three-necked flask, then add 0.5g of p-toluenesulfonic acid. Stir at 200r / min at 125℃ for 9h, then add 2.5g of 2-aminoethanethiol and stir at 80℃ for 4h to obtain a hyperbranched polyester containing disulfide bonds. Heat 130g of the second modified resin to 125℃, add 0.2g of light stabilizer 770, stir for 15min, slowly add the hyperbranched polyester containing disulfide bonds, introduce ozone at a concentration of 15ppm, and react for 4.5h. After the reaction is complete, add 1.5g of microencapsulated benzoyl peroxide and stir for 30min until uniformly dispersed.

[0030] Example 5: Preparation of self-healing microcapsules. The specific preparation steps are as follows: B1. Add 10g of core material dicyclopentadiene and 20g of wall material urea-formaldehyde resin to a three-necked flask, then add 0.75g of polyethylene glycol octylphenyl ether and 80g of deionized water. Emulsify in a high-speed shear emulsifier at 12000r / min for 12min, adjust the pH of the system to 4, raise the temperature to 45℃, add 12g of 37% formaldehyde solution dropwise while stirring at 350r / min, and continue the reaction for 2.5h after the addition is complete; then add 1.25g of melamine-formaldehyde resin and stir at 55℃ for 1.5h; finally add 0.4g of nano silica particles and stir at 200r / min for 10min. B2. Mix 3g of silane coupling agent KH-550 with 1.5g of hydroxyethyl methacrylate, dissolve in 400mL of ethanol-water solution with a volume ratio of 9:1, add 0.2g of dibutyltin dilaurate to prepare a functionalized solution; add the first modified microcapsules to the functionalized solution, ultrasonically disperse for 45min, then add 1.5g of Fe3O4 magnetic nanoparticles, filter and separate, wash with deionized water, and vacuum dry at 65℃ for 9h to obtain surface-functionalized microcapsules; B3. Mix 6g of nanocellulose and 1.5g of chitosan, dissolve in 100mL of 1% acetic acid solution, and ultrasonically disperse for 15min to form a uniform composite solution. Adjust the pH of the solution to 5.5, add 0.8g of calcium chloride, stir for 35min, then add the second modified microcapsules and stir for 1.5h. Subsequently, treat by spray drying, controlling the inlet temperature to 125℃ and the outlet temperature to 75℃ to form microcapsule-biopolymer composite particles. Finally, immerse the composite particles in 100mL of phosphate buffer solution of glucose oxidase with a concentration of 1.5mg / mL and react at 35℃ for 36h to immobilize the enzyme on the particle surface.

[0031] Comparative Example 1: A moisture-proof curing agent for use in PCB circuit board coatings was prepared. The specific preparation steps are as follows: The remaining steps remain the same, except that the modified acrylic resin in Example 3 is replaced with untreated acrylic resin to prepare a moisture-proof curing agent for use in PCB circuit board coatings.

[0032] Comparative Example 2: A moisture-proof curing agent for use in PCB circuit board coatings was prepared. The specific preparation steps are as follows: The remaining steps remain the same, except that the self-healing microcapsules of Example 3 are replaced with empty microcapsules without the repair agent to prepare a moisture-proof curing agent for use in PCB circuit board coatings. Based on the performance test standards and results, the moisture-proof curing agents in Examples 1-3 exhibited excellent performance in multiple performance indicators. Regarding moisture resistance, they demonstrated low water absorption, with Example 3 achieving an absorption rate of 0.28%; high hardness, with a Shore D hardness between 72 and 75; excellent adhesion (all at grade 0); good temperature resistance, with a heat distortion temperature between 145℃ and 152℃; and strong impact resistance, with values ​​between 32 and 35 kJ / m². 2 It exhibits high self-healing efficiency, reaching 85%-90% within 24 hours; and excellent weather resistance, showing no significant change after 1000 hours of UV aging. In contrast, Comparative Example 1, which uses untreated acrylic resin instead of modified acrylic resin, has a water absorption rate of 0.65%, a hardness of 68, a heat distortion temperature of 135℃, and an impact resistance of 28kJ / m². 2 After UV aging, it showed slight discoloration and relatively poor performance in various aspects. Comparative Example 2, which used empty microcapsules without repair agents instead of self-healing microcapsules, had a self-healing efficiency of 0, and its water absorption and impact resistance were also inferior to those of the Example.

[0033] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A moisture-proof curing agent for use in PCB circuit board coatings, characterized in that: It contains the following raw materials in parts by weight: 30-50 parts epoxy resin, 20-35 parts polyurethane prepolymer, 10-15 parts nano silica, 5-10 parts methyltrimethoxysilane, 3-8 parts γ-aminopropyltriethoxysilane, 0.5-2 parts dibutyltin dilaurate, 2-5 parts 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 1-3 parts antioxidant 1076, 8-12 parts tripropylene glycol diacrylate, 5-8 parts polytetrafluoroethylene micropowder, 4-7 parts self-healing microcapsules, and 20-30 parts modified acrylic resin.

2. The moisture-proof curing agent for PCB circuit board coatings according to claim 1, characterized in that: The epoxy resin is one of bisphenol A type epoxy resin and bisphenol F type epoxy resin; the nano silica particles have a particle size of 10-50nm and have undergone surface modification treatment with silane coupling agent.

3. The moisture-proof curing agent for PCB circuit board coatings according to claim 1, characterized in that: The polyurethane prepolymer is prepared from hexamethylene diisocyanate and polytetrahydrofuran diol, wherein the number-average molecular weight of polytetrahydrofuran diol is 1500.

4. The moisture-proof curing agent for PCB circuit board coatings according to claim 1, characterized in that: The modified acrylic resin is prepared using the following specific steps: A1. Place anatase nano-titanium dioxide into a plasma reaction chamber, introduce a mixture of oxygen and argon gas with a volume ratio of 1:3, and remove it after 10 minutes. Prepare a composite coupling agent by combining silane coupling agent KH-570 with nano-silver particles. Add acrylic resin to the reactor, heat to 85℃ to melt, and add the treated nano-titanium dioxide, composite coupling agent, and glycidyl methacrylate in sequence under stirring at 200 r / min. Disperse ultrasonically for 2.5 h, and irradiate with 365 nm ultraviolet light for 30 minutes before the end of the reaction. After the reaction is completed, cool to room temperature. A2. Carbon nanotubes and sodium dodecylbenzenesulfonate were added to N-methylpyrrolidone and sonicated for 1.5 h to obtain a carbon nanotube dispersion. Graphene oxide, N-isopropylacrylamide, and ammonium persulfate were taken and stirred at 55℃ for 300 r / min for 5 h to generate a thermosensitive graphene composite material. The first modified resin was heated to 65℃, and carbon nanotube dispersion and dibutyltin dilaurate were added dropwise under nitrogen protection. The temperature was raised to 105℃, and the thermosensitive graphene composite material was added. The mixture was stirred at 300 r / min for 3.5 h under 8 MPa pressure. A3. Dithiodipropionic acid and trimethylolpropane were added to a three-necked flask, followed by p-toluenesulfonic acid. The mixture was stirred at 200 rpm for 9 hours at 125°C. Then, 2-aminoethanethiol was added, and the mixture was reacted at 80°C for 4 hours to obtain a hyperbranched polyester containing disulfide bonds. The modified resin was heated to 125°C, and light stabilizer 770 was added. The mixture was stirred at 200 rpm for 15 minutes. The hyperbranched polyester containing disulfide bonds was slowly added, and ozone at a concentration of 15 ppm was introduced. The mixture was stirred at 300 rpm for 4.5 hours. After the reaction was completed, microencapsulated benzoyl peroxide was added, and the mixture was stirred for 30 minutes until it was uniformly dispersed.

5. The moisture-proof curing agent for PCB circuit board coatings according to claim 4, characterized in that: The silane coupling agent KH-570 in A1 is combined with silver nanoparticles to form a composite coupling agent, and the specific method is as follows: The silane coupling agent KH-570 and nano-silver particles were added to anhydrous ethanol, followed by the addition of 3-mercaptopropionic acid. The mixture was then shaken at 300 r / min for 15 min under a constant temperature water bath at 30℃, with a shaking frequency of 50 Hz, while simultaneously introducing a 5% H2 / Ar mixed gas. After mixing, the mixture was dried in a vacuum drying oven at 60℃ for 2 h, and then annealed at 120℃ under a nitrogen atmosphere for 1 h to obtain a uniformly dispersed composite coupling agent.

6. The moisture-proof curing agent for PCB circuit board coatings according to claim 5, characterized in that: The composite coupling agent contains silane coupling agent KH-570, nano-silver particles, anhydrous ethanol, and 3-mercaptopropionic acid in a ratio of 7g:0.8g:35g:0.5g. The flow rate of the mixed gas is 20mL / min. The nano-silver particles have a particle size of 5-10nm, and their surface is modified with sodium citrate, resulting in a zeta potential of -30mV to -40mV.

7. The moisture-proof curing agent for PCB circuit board coatings according to claim 4, characterized in that: The ratio of acrylic resin, nano titanium dioxide, composite coupling agent, and glycidyl methacrylate in A1 is 100g:20g:7.8g:4g; the ratio of silane coupling agent KH-570 and nano silver particles is 7g:0.8g. The ratio of carbon nanotubes, sodium dodecylbenzenesulfonate, and N-methylpyrrolidone in A2 is 12g:4g:100g; the ratio of graphene oxide, N-isopropylacrylamide, and ammonium persulfate is 5g:10g:0.5g; the ratio of the first modified resin and dibutyltin dilaurate is 130g:2.5g; and the nitrogen flow rate is 50mL / min. The ratio of dithiodipropionic acid, trimethylolpropane, p-toluenesulfonic acid, and 2-aminoethanethiol in A3 is 10g:4.2g:0.5g:2.5g; the ratio of the second modified resin, light stabilizer 770, and microencapsulated benzoyl peroxide is 130g:0.2g:1.5g.

8. The moisture-proof curing agent for PCB circuit board coatings according to claim 1, characterized in that: The self-healing microcapsules are prepared using the following specific steps: B1. Dicyclopentadiene (core material) and urea-formaldehyde resin (wall material) were added to a three-necked flask, followed by polyethylene glycol octylphenyl ether and deionized water. The mixture was emulsified at 12,000 rpm for 12 minutes in a high-speed shear emulsifier. The pH of the system was adjusted to 4, and the temperature was raised to 45°C. A 37% formaldehyde solution was added dropwise while stirring at 350 rpm. After the addition was complete, the reaction was continued for 2.5 hours. Melamine-formaldehyde resin was then added, and the reaction was continued at 55°C with stirring for 1.5 hours. Finally, nano-silica particles were added, and the mixture was stirred at 200 rpm for 10 minutes. B2. Mix silane coupling agent KH-550 with hydroxyethyl methacrylate and dissolve in an ethanol-water solution with a volume ratio of 9:

1. Add dibutyltin dilaurate to prepare a functionalized solution. Add the first modified microcapsules to the functionalized solution, sonicate for 45 min, then add Fe3O4 magnetic nanoparticles, filter and separate, wash with deionized water, and vacuum dry at 65℃ for 9 h to obtain surface-functionalized microcapsules. B3. Nanocellulose and chitosan were mixed and dissolved in 1% acetic acid solution. The mixture was ultrasonically dispersed for 15 min to form a uniform composite solution. The pH of the solution was adjusted to 5.5, calcium chloride was added, and the mixture was stirred at 200 r / min for 35 min. Then, the second modified microcapsules were added and stirred for 1.5 h. Subsequently, the mixture was treated by spray drying, with the inlet temperature controlled at 125℃ and the outlet temperature at 75℃, to form microcapsule-biopolymer composite particles. Finally, the composite particles were immersed in a phosphate buffer solution of 1.5 mg / mL glucose oxidase and reacted at 35℃ for 36 h to immobilize the enzyme on the particle surface.

9. A moisture-proof curing agent for PCB circuit board coatings according to claim 8, characterized in that: The ratio of dicyclopentadiene, urea-formaldehyde resin, polyethylene glycol octylphenyl ether, deionized water, formaldehyde solution, melamine-formaldehyde resin, and nano-silica particles in B1 is 10g:20g:0.75g:80g:12g:1.25g:0.4g. The ratio of silane coupling agent KH-550 to hydroxyethyl methacrylate, ethanol-water solution, dibutyltin dilaurate, and Fe3O4 magnetic nanoparticles in B2 is 3g:1.5g:400mL:0.2g:1.5g; In B3, the ratio of nanocellulose, chitosan, acetic acid solution, calcium chloride, and glucose oxidase phosphate buffer solution is 6g:1.5g:100mL:0.8g:100mL.

10. A method for preparing a moisture-proof curing agent for use in PCB circuit board coatings, characterized in that: Specifically, it includes the following steps: S1. Add epoxy resin, polyurethane prepolymer and tripropylene glycol diacrylate into the reactor, heat to 60℃, and stir at 300r / min for 20min. S2. While maintaining the stirring state, add nano silica, methyltrimethoxysilane, γ-aminopropyltriethoxysilane, and dibutyltin dilaurate in sequence. Stir for 5 minutes after each addition of raw material, and continue stirring at 300 r / min for 30 minutes after all raw materials have been added. S3. Reduce the temperature of the reactor to 40°C, and add 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, antioxidant 1076, polytetrafluoroethylene micro powder, and modified acrylic resin in sequence. Stir at 400 r / min for 1.5 h. S4. Finally, add the self-healing microcapsules and stir at 250 rpm for 30 minutes to obtain the moisture-proof curing agent.