A hydrophobic and oleophobic circuit board for a smoke-resistant microphone and a preparation method thereof

Abstract

The present application relates to the technical field of electronic component protection, and particularly relates to a hydrophobic and oleophobic circuit board for a smoke-resistant microphone head and a preparation method thereof.The present application adds 2-hydroxy-2-methyl-1-phenylpropanone and silica filler into fluorosilicon resin, and obtains hydrophobic and oleophobic paint after fully stirring for 30-50 min.The present application adds silica filler into anhydrous ethanol, and obtains silica paint after uniformly ultrasonic dispersion.The surface of the circuit board for the microphone head is drilled and cleaned to obtain a circuit board with surface micropores; the hydrophobic and oleophobic paint is sprayed onto the surface of the circuit board, and the silica paint is sprayed after ultraviolet curing, and the hydrophobic and oleophobic circuit board product is obtained after solvent evaporation.The product prepared by the present application has excellent antibacterial property and hydrophobic and oleophobic property, and therefore has wide application prospects in the technical field of electronic component protection.

Description

Technical Field

[0001] This invention relates to the field of electronic component protection technology, specifically to a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid and its preparation method. Background Technology

[0002] In this era of rapid technological advancement, microphone circuit boards, though seemingly ordinary, play an irreplaceable role in numerous fields, demonstrating immense modern value. In the electronics industry, especially in e-cigarettes, as a typical atomizing device, they have garnered widespread attention due to their unique working principle and user experience. Within e-cigarettes and other electronic products, the microphone circuit board is considered one of the core components. Specifically, the microphone circuit board is responsible for receiving and processing signals from the microphone and precisely controlling the battery's power supply to the atomizer, thereby achieving stable atomization of e-liquid.

[0003] As shown above, microphones are widely used in devices that come into close contact with people. However, during use, the circuit board can become contaminated with oils and sweat secreted by human skin, as well as dust and microorganisms from the surrounding environment. If the circuit board lacks good antibacterial properties, bacteria, fungi, and other microorganisms will proliferate on it. These microorganisms not only emit unpleasant odors but may also spread through the air, posing a potential threat to human health, especially for people with weakened immune systems. Therefore, improving antibacterial properties can effectively inhibit the growth of microorganisms, creating a healthier and safer usage environment for users. Furthermore, circuit boards contain numerous delicate electronic components and circuits. Contact with water or oil can trigger a series of problems. Water can cause short circuits, preventing the device from functioning properly and even damaging electronic components, shortening the device's lifespan. Oily substances can attract dust, forming dirt that affects the circuit board's heat dissipation performance, leading to abnormal overheating and consequently affecting the microphone's sensitivity. Therefore, improving the hydrophobic and oleophobic properties of the circuit board can effectively prevent the intrusion of water and oil, ensuring stable operation of the device under various complex environmental conditions and improving its reliability and durability.

[0004] To overcome the shortcomings of the prior art, the present invention provides a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid and a method for preparing the same. Summary of the Invention

[0005] The purpose of this invention is to provide a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid and its preparation method, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid includes the following steps:

[0008] Step 1: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane are added to ethylene glycol dimethyl ether. The mixture is slowly heated to 75-80℃ and hydrochloric acid is added to adjust the pH to 4-5. After stirring for 1.5-2.0 h, deionized water is added dropwise. After the addition is complete, the reaction continues for 7-8 h. The fluorosilicone resin is obtained by rotary evaporation of the solvent and dilution with anhydrous ethanol.

[0009] Step 2: Add 2-hydroxy-2-methyl-1-phenylpropanone and silica filler to fluorosilicone resin, stir thoroughly for 30-50 minutes to obtain a hydrophobic and oleophobic coating; add silica filler to anhydrous ethanol, ultrasonically disperse for 20-30 minutes to obtain a silica coating.

[0010] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0011] In a more optimized manner, in step one, the reaction mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water is 2 mL : (1.4-1.6) mL : (1.8-2.2) mL : (1.0-1.3) g : 1 mL : 1 mL : (1.2-1.3) mL.

[0012] A more optimized preparation process for siloxane polymers is as follows:

[0013] Step S1: Add chitosan to deionized water, stir evenly, then add 2,3-epoxypropyltrimethylammonium chloride, and react at 80-85℃ for 14-15 hours. After the reaction is completed, the mixture is precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan.

[0014] Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 0-2℃ for 1.5-2.0h. After stirring, slowly add acryloyl chloride and continue the reaction for 8-10h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash and dry to obtain chitosan antibacterial monomer.

[0015] Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile and stirred until homogeneous. Then, 3-chloro-2-chloromethylpropene was slowly added. After the addition was completed, the temperature was slowly raised to 60-70℃ and the mixture was stirred for 15-18 hours. After the reaction was completed, the mixture was washed, filtered and dried to obtain the quaternary phosphonium salt antibacterial monomer.

[0016] Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile are added to tetrahydrofuran, stirred evenly, and refluxed at 70-75℃ for 12-14 hours. After the reaction is completed, the product is precipitated, washed, and dried to obtain the siloxane polymer.

[0017] In a more optimized manner, when preparing chitosan antibacterial monomers, the reaction mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride is 1:(4.0-4.5); the reaction mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3g:15mL:(9-11)mL.

[0018] In a more optimized manner, in step S3, the molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene is 1:(1.0-1.1).

[0019] In a more optimized manner, in step S4, the molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane is (8-9):(4-5):(2-3):(12-14); and the azobisisobutyronitrile is 0.02-0.03 wt% of the total mass of the reactants.

[0020] A more optimized preparation process for silica filler is as follows: anhydrous ethanol and 20-25 wt% ammonia are mixed and stirred at 30-35℃ for 30-40 min. Then, tetraethyl orthosilicate is added and the mixture is stirred for another 2-3 h. After the reaction is complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate are added dropwise. After the addition is complete, the mixture is stirred for another 2.5-3.5 h. After the reaction is complete, the silica filler is obtained by centrifugation, washing, and drying.

[0021] In a more optimized manner, the reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane is 250:20:20:(0.5-0.7); and the dibutyltin dilaurate is 0.03-0.05 wt% of the total mass of the reactants.

[0022] In a more optimized manner, in step two, the content of each component of the hydrophobic and oleophobic coating is as follows: by mass parts, 3-5 parts of 2-hydroxy-2-methyl-1-phenylpropanone, 15-20 parts of silica filler, and 90-100 parts of fluorosilicone resin; the mass-volume ratio of silica filler to anhydrous ethanol is 1g:(8-10)mL.

[0023] The beneficial effects of this invention are:

[0024] The key feature of this invention is that, in step one, a ring-opening reaction is initiated by adding chitosan and 2,3-epoxypropyltrimethylammonium chloride to introduce an antibacterial quaternary ammonium salt, resulting in modified chitosan. The modified chitosan is then added to methanesulfonic acid to undergo a nucleophilic substitution reaction, introducing a carbon-carbon double bond to obtain a chitosan antibacterial monomer. A nucleophilic substitution reaction is then initiated by adding tris(4-methoxyphenyl)phosphine and 3-chloro-2-chloromethylpropene to obtain a quaternary phosphonium salt antibacterial monomer. The chitosan itself contains amino groups, which have a certain inhibitory effect on some bacteria; and the quaternary ammonium salt has a positively charged center, which can strongly bind to negatively charged substances on the bacterial surface, disrupting the integrity of the bacterial cell membrane and leading to bacterial death. Furthermore, the subsequent introduction of a carbon-carbon double bond through a nucleophilic substitution reaction to form the chitosan antibacterial monomer not only retains the antibacterial function but also possesses an active site for participating in thiol-alkene reactions. Quaternary phosphonium salts in antibacterial monomers are similar to quaternary ammonium salts, having a positive charge. They can adsorb and penetrate bacterial cell membranes, interfering with the normal physiological activities of bacteria and exerting antibacterial effects.

[0025] Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile are then mixed and subjected to a mercapto-olefin click reaction to obtain a siloxane polymer. In the mercapto-olefin click reaction, the carbon-carbon double bonds on the chitosan and quaternary phosphonium salt antibacterial monomers react with the thiol groups of 3-mercaptopropyltriethoxysilane, firmly integrating the antibacterial groups into the molecular chain of the siloxane polymer. This ensures the stability of the antibacterial groups in the polymer, preventing them from being lost and allowing for sustained antibacterial activity. Trifluoroethyl methacrylate also enters the polymer structure through the mercapto-olefin click reaction, causing fluorine atoms to arrange themselves in an orderly manner on the polymer surface, forming a low-surface-energy fluoride layer. According to surface chemistry principles, the low surface energy leads to an increased contact angle between water and oil and the polymer surface, making it difficult for liquids to spread, thus achieving hydrophobicity and oleophobicity.

[0026] Next, perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water are mixed and subjected to a hydrolysis reaction to obtain fluorosilicone resin. Perfluorooctyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane are key raw materials that impart hydrophobic and oleophobic properties to fluorosilicone resin. Fluorine atoms have extremely high electronegativity and small atomic radii, resulting in fluorocarbon chains with extremely low surface energy. When water or oil comes into contact with the surface of fluorosilicone resin, due to the low surface energy, the interaction force between water and oil molecules and the surface is very weak, making it difficult for them to spread on the surface, thus forming a large contact angle and exhibiting significant hydrophobic and oleophobic properties. Moreover, the long-chain fluorocarbon structure increases the flexibility and steric hindrance of the molecules, further enhancing the repulsion of water and oil. The methyl groups attached to the silicon atoms in hydroxypropyl-terminated polydimethylsiloxane have low polarity and surface energy, which helps to reduce the overall surface energy of the resin. This, combined with fluorinated silanes, enhances the hydrophobic and oleophobic properties. Therefore, during the hydrolysis reaction, the above raw materials gradually polymerize to form a three-dimensional network structure of fluorosilicone resin. This allows the fluorinated groups, low-surface-energy methyl groups, and antibacterial materials to be uniformly distributed in the resin and stably present on the surface, collectively endowing the fluorosilicone resin with excellent antibacterial and hydrophobic / oleophobic properties.

[0027] The invention is characterized in that, in step two, silica filler is prepared by adding anhydrous ethanol, ammonia, tetraethyl orthosilicate, heptadecafluorodecyltrimethoxysilane, and dibutyltin dilaurate. 2-hydroxy-2-methyl-1-phenylpropanone and silica filler are added to fluorosilicone resin and stirred to obtain a hydrophobic and oleophobic coating; silica filler is then added to anhydrous ethanol to obtain a silica coating. The hydrophobic and oleophobic coating is sprayed onto the surface of a circuit board with micropores, cured under ultraviolet light, and then the silica coating is sprayed again. After solvent evaporation, the hydrophobic and oleophobic circuit board is obtained.

[0028] In the preparation of silica fillers, heptadecafluorodecyltrimethoxysilane participates in the reaction, and its fluorine-containing groups are distributed on the surface of the silica filler. When the silica filler is applied to a circuit board coating, fluorine atoms accumulate on the coating surface, forming a low-surface-energy fluoride layer. Water and oil molecules have difficulty spreading on the surface, thus giving the circuit board excellent hydrophobic and oleophobic properties. Furthermore, when silica coating is sprayed onto a cured hydrophobic and oleophobic coating, the solvent evaporates, forming a rough hydrophobic surface. This rough surface increases the actual contact area between water and oil and the coating surface. However, the coating itself has a low-surface-energy fluoride layer, and this increased contact area further reduces the wettability of water and oil on the surface, making it even more difficult for water and oil to spread, thereby improving the hydrophobic and oleophobic properties. Simultaneously, this rough surface is unfavorable for bacterial attachment and movement; bacteria find it difficult to find suitable living space in such a complex surface environment, thus enhancing the antibacterial effect.

[0029] In summary, the finished product prepared by this invention has excellent antibacterial and hydrophobic / oleophobic properties, and therefore has broad application prospects in the field of electronic component protection technology. Detailed Implementation

[0030] 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.

[0031] Raw material source:

[0032] Chitosan, provided by Shandong Pingju Biotechnology Co., Ltd., has a degree of deacetylation ≥80%; hydroxypropyl-terminated polydimethylsiloxane, provided by Guangdong Wengjiang Chemical Reagent Co., Ltd., has an active ingredient content of 65%; one part by weight is 1g.

[0033] Example 1: Step 1: Step S1: Chitosan was added to deionized water and stirred evenly. Then 2,3-epoxypropyltrimethylammonium chloride was added and reacted at 85°C for 15 hours. After the reaction was completed, the mixture was precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan. The mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride was 1:4.3.

[0034] Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 2°C for 2.0 h. After stirring, slowly add acryloyl chloride and continue the reaction for 10 h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash, and dry to obtain chitosan antibacterial monomer. The mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3 g: 15 mL: 10 mL.

[0035] Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile, stirred until homogeneous, and then 3-chloro-2-chloromethylpropene was slowly added. After the addition was complete, the temperature was slowly raised to 70°C and the mixture was stirred for 18 hours. After the reaction was completed, the mixture was washed, filtered, and dried to obtain the quaternary phosphonium salt antibacterial monomer. The molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene was 1:1.05.

[0036] Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile were added to tetrahydrofuran, stirred until homogeneous, and refluxed at 75°C for 14 h. After the reaction was completed, the mixture was precipitated, washed, and dried to obtain a siloxane polymer. The molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane was 8.5:4.5:2.5:13; the azobisisobutyronitrile content was 0.025 wt% of the total reactants.

[0037] Step S5: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to ethylene glycol dimethyl ether. The mixture was slowly heated to 80°C, and hydrochloric acid was added to adjust the pH to 5. After stirring for 2.0 h, deionized water was added dropwise. After the addition was complete, the reaction continued for 8 h. The fluorosilicone resin was obtained by rotary evaporation of the solvent and dilution with anhydrous ethanol. The mass-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2 mL: 1.5 mL: 2 mL: 1.2 g: 1 mL: 1 mL: 1.25 mL.

[0038] Step 2: Anhydrous ethanol and 25 wt% ammonia were mixed and stirred at 35°C for 40 min. Tetraethyl orthosilicate was then added, and the reaction was continued for 3 h. After the reaction was complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate were added dropwise. Stirring was continued for 3.5 h after the addition was complete. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain silica filler. The reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane was 250:20:20:0.6; dibutyltin dilaurate accounted for 0.04 wt% of the total reactants.

[0039] 5g of 2-hydroxy-2-methyl-1-phenylpropanone and 20g of silica filler were added to 100g of fluorosilicone resin and stirred thoroughly for 50min to obtain a hydrophobic and oleophobic coating; silica filler was added to anhydrous ethanol and ultrasonically dispersed for 30min to obtain a silica coating; the mass-volume ratio of silica filler to anhydrous ethanol was 1g:9mL.

[0040] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0041] Example 2: Step 1: Step S1: Chitosan was added to deionized water and stirred evenly. Then 2,3-epoxypropyltrimethylammonium chloride was added, and the mixture was reacted at 82°C for 14.5 h. After the reaction was completed, the mixture was precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan. The mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride was 1:4.3.

[0042] Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 1°C for 1.7 h. After stirring, slowly add acryloyl chloride and continue the reaction for 9 h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash, and dry to obtain chitosan antibacterial monomer. The mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3 g: 15 mL: 10 mL.

[0043] Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile, stirred until homogeneous, and then 3-chloro-2-chloromethylpropene was slowly added. After the addition was complete, the temperature was slowly raised to 65°C and the mixture was stirred for 17 hours. After the reaction was completed, the mixture was washed, filtered, and dried to obtain the quaternary phosphonium salt antibacterial monomer. The molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene was 1:1.05.

[0044] Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile were added to tetrahydrofuran, stirred until homogeneous, and refluxed at 72°C for 13 h. After the reaction was completed, the mixture was precipitated, washed, and dried to obtain a siloxane polymer. The molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane was 8.5:4.5:2.5:13; the azobisisobutyronitrile content was 0.025 wt% of the total reactants.

[0045] Step S5: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to ethylene glycol dimethyl ether. The mixture was slowly heated to 77°C, and hydrochloric acid was added to adjust the pH to 4.5. After stirring for 1.7 h, deionized water was added dropwise. After the addition was complete, the reaction was continued for 7.5 h. The fluorosilicone resin was obtained by rotary evaporation of the solvent and dilution with anhydrous ethanol. The mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2 mL: 1.5 mL: 2 mL: 1.2 g: 1 mL: 1 mL: 1.25 mL.

[0046] Step 2: Anhydrous ethanol and 25 wt% ammonia were mixed and stirred at 32°C for 35 min. Tetraethyl orthosilicate was then added, and the reaction was continued for 2.5 h. After the reaction was complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate were added dropwise. Stirring was continued for 3 h after the addition was complete. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain silica filler. The reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane was 250:20:20:0.6; dibutyltin dilaurate accounted for 0.04 wt% of the total reactants.

[0047] 5g of 2-hydroxy-2-methyl-1-phenylpropanone and 20g of silica filler were added to 100g of fluorosilicone resin and stirred thoroughly for 40min to obtain a hydrophobic and oleophobic coating; silica filler was added to anhydrous ethanol and ultrasonically dispersed for 25min to obtain a silica coating; the mass-volume ratio of silica filler to anhydrous ethanol was 1g:9mL.

[0048] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0049] Example 3: Step 1: Step S1: Chitosan was added to deionized water and stirred evenly. Then 2,3-epoxypropyltrimethylammonium chloride was added and reacted at 80°C for 14 hours. After the reaction was completed, the mixture was precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan. The mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride was 1:4.3.

[0050] Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 0℃ for 1.5h. After stirring, slowly add acryloyl chloride and continue the reaction for 8h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash, and dry to obtain chitosan antibacterial monomer. The mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3g:15mL:10mL.

[0051] Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile, stirred until homogeneous, and then 3-chloro-2-chloromethylpropene was slowly added. After the addition was complete, the temperature was slowly raised to 60°C and the mixture was stirred for 15 hours. After the reaction was completed, the mixture was washed, filtered, and dried to obtain the quaternary phosphonium salt antibacterial monomer. The molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene was 1:1.05.

[0052] Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile were added to tetrahydrofuran, stirred until homogeneous, and refluxed at 70°C for 12 hours. After the reaction was completed, the mixture was precipitated, washed, and dried to obtain a siloxane polymer. The molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane was 8.5:4.5:2.5:13; the azobisisobutyronitrile content was 0.025 wt% of the total reactants.

[0053] Step S5: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to ethylene glycol dimethyl ether. The mixture was slowly heated to 75°C, and hydrochloric acid was added to adjust the pH to 4. After stirring for 1.5 h, deionized water was added dropwise. After the addition was complete, the reaction was continued for 7 h. The fluorosilicone resin was obtained by rotary evaporation of the solvent and dilution with anhydrous ethanol. The mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2 mL: 1.5 mL: 2 mL: 1.2 g: 1 mL: 1 mL: 1.25 mL.

[0054] Step 2: Anhydrous ethanol and 25 wt% ammonia were mixed and stirred at 30°C for 30 min. Tetraethyl orthosilicate was then added, and the reaction was continued for 2 h. After the reaction was complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate were added dropwise. Stirring was continued for 2.5 h after the addition was complete. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain silica filler. The reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane was 250:20:20:0.6; dibutyltin dilaurate accounted for 0.04 wt% of the total reactants.

[0055] 5g of 2-hydroxy-2-methyl-1-phenylpropanone and 20g of silica filler were added to 100g of fluorosilicone resin and stirred thoroughly for 30min to obtain a hydrophobic and oleophobic coating; silica filler was added to anhydrous ethanol and ultrasonically dispersed for 20min to obtain a silica coating; the mass-volume ratio of silica filler to anhydrous ethanol was 1g:9mL.

[0056] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0057] Comparative Example 1: The reaction mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl dimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane was adjusted to 2 mL: 1 mL: 1 mL: 0.5 g: 1 mL: 1 mL. The rest was the same as in Example 1. The specific steps are as follows: Step 1: Step S1: Chitosan was added to deionized water and stirred evenly. Then 2,3-epoxypropyltrimethylammonium chloride was added, and the mixture was reacted at 85°C for 15 h. After the reaction was completed, the mixture was precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan. The reaction mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride was 1:4.3.

[0058] Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 2°C for 2.0 h. After stirring, slowly add acryloyl chloride and continue the reaction for 10 h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash, and dry to obtain chitosan antibacterial monomer. The mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3 g: 15 mL: 10 mL.

[0059] Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile, stirred until homogeneous, and then 3-chloro-2-chloromethylpropene was slowly added. After the addition was complete, the temperature was slowly raised to 70°C and the mixture was stirred for 18 hours. After the reaction was completed, the mixture was washed, filtered, and dried to obtain the quaternary phosphonium salt antibacterial monomer. The molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene was 1:1.05.

[0060] Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile were added to tetrahydrofuran, stirred until homogeneous, and refluxed at 75°C for 14 h. After the reaction was completed, the mixture was precipitated, washed, and dried to obtain a siloxane polymer. The molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane was 8.5:4.5:2.5:13; the azobisisobutyronitrile content was 0.025 wt% of the total reactants.

[0061] Step S5: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to ethylene glycol dimethyl ether. The mixture was slowly heated to 80°C, and hydrochloric acid was added to adjust the pH to 5. After stirring for 2.0 h, deionized water was added dropwise. After the addition was complete, the reaction was continued for 8 h. The fluorosilicone resin was obtained by rotary evaporation of the solvent and dilution with anhydrous ethanol. The mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2 mL: 1 mL: 1 mL: 0.5 g: 1 mL: 1 mL: 1.25 mL.

[0062] Step 2: Anhydrous ethanol and 25 wt% ammonia were mixed and stirred at 35°C for 40 min. Tetraethyl orthosilicate was then added, and the reaction was continued for 3 h. After the reaction was complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate were added dropwise. Stirring was continued for 3.5 h after the addition was complete. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain silica filler. The reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane was 250:20:20:0.6; dibutyltin dilaurate accounted for 0.04 wt% of the total reactants.

[0063] 5g of 2-hydroxy-2-methyl-1-phenylpropanone and 20g of silica filler were added to 100g of fluorosilicone resin and stirred thoroughly for 50min to obtain a hydrophobic and oleophobic coating; silica filler was added to anhydrous ethanol and ultrasonically dispersed for 30min to obtain a silica coating; the mass-volume ratio of silica filler to anhydrous ethanol was 1g:9mL.

[0064] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0065] Comparative Example 2: The reaction mass-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl dimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane was adjusted to 2 mL:2 mL:3 mL:2 g:1 mL:1 mL, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: Step S1: Chitosan was added to deionized water, stirred evenly, and then 2,3-epoxypropyltrimethylammonium chloride was added. The reaction was carried out at 85°C for 15 h. After the reaction was completed, the mixture was precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan. The reaction mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride was 1:4.3.

[0066] Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 2°C for 2.0 h. After stirring, slowly add acryloyl chloride and continue the reaction for 10 h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash, and dry to obtain chitosan antibacterial monomer. The mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3 g: 15 mL: 10 mL.

[0067] Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile, stirred until homogeneous, and then 3-chloro-2-chloromethylpropene was slowly added. After the addition was complete, the temperature was slowly raised to 70°C and the mixture was stirred for 18 hours. After the reaction was completed, the mixture was washed, filtered, and dried to obtain the quaternary phosphonium salt antibacterial monomer. The molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene was 1:1.05.

[0068] Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile were added to tetrahydrofuran, stirred until homogeneous, and refluxed at 75°C for 14 h. After the reaction was completed, the mixture was precipitated, washed, and dried to obtain a siloxane polymer. The molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane was 8.5:4.5:2.5:13; the azobisisobutyronitrile content was 0.025 wt% of the total reactants.

[0069] Step S5: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to ethylene glycol dimethyl ether. The mixture was slowly heated to 80°C, and hydrochloric acid was added to adjust the pH to 5. After stirring for 2.0 h, deionized water was added dropwise. After the addition was complete, the reaction was continued for 8 h. The fluorosilicone resin was obtained by rotary evaporation of the solvent and dilution with anhydrous ethanol. The mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2 mL: 2 mL: 3 mL: 2 g: 1 mL: 1 mL: 1.25 mL.

[0070] Step 2: Anhydrous ethanol and 25 wt% ammonia were mixed and stirred at 35°C for 40 min. Tetraethyl orthosilicate was then added, and the reaction was continued for 3 h. After the reaction was complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate were added dropwise. Stirring was continued for 3.5 h after the addition was complete. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain silica filler. The reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane was 250:20:20:0.6; dibutyltin dilaurate accounted for 0.04 wt% of the total reactants.

[0071] 5g of 2-hydroxy-2-methyl-1-phenylpropanone and 20g of silica filler were added to 100g of fluorosilicone resin and stirred thoroughly for 50min to obtain a hydrophobic and oleophobic coating; silica filler was added to anhydrous ethanol and ultrasonically dispersed for 30min to obtain a silica coating; the mass-volume ratio of silica filler to anhydrous ethanol was 1g:9mL.

[0072] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0073] Comparative Example 3: The siloxane polymer was removed, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to ethylene glycol dimethyl ether. The temperature was slowly raised to 80°C, and hydrochloric acid was added to adjust the pH to 5. After stirring for 2.0 h, deionized water was added dropwise. After the addition was completed, the reaction continued for 8 h. The fluorosilicone resin was obtained by rotary evaporation of solvent and dilution with anhydrous ethanol. The reaction volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2:1.5:2:1:1:1.25.

[0074] Step 2: Anhydrous ethanol and 25 wt% ammonia were mixed and stirred at 35°C for 40 min. Tetraethyl orthosilicate was then added, and the reaction was continued for 3 h. After the reaction was complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate were added dropwise. Stirring was continued for 3.5 h after the addition was complete. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain silica filler. The reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane was 250:20:20:0.6; dibutyltin dilaurate accounted for 0.04 wt% of the total reactants.

[0075] 5g of 2-hydroxy-2-methyl-1-phenylpropanone and 20g of silica filler were added to 100g of fluorosilicone resin and stirred thoroughly for 50min to obtain a hydrophobic and oleophobic coating; silica filler was added to anhydrous ethanol and ultrasonically dispersed for 30min to obtain a silica coating; the mass-volume ratio of silica filler to anhydrous ethanol was 1g:9mL.

[0076] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0077] Comparative Example 4: The silica coating was removed, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: Step S1: Chitosan was added to deionized water, stirred evenly, and then 2,3-epoxypropyltrimethylammonium chloride was added. The mixture was reacted at 85°C for 15 hours. After the reaction was completed, the mixture was precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan. The mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride was 1:4.3.

[0078] Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 2°C for 2.0 h. After stirring, slowly add acryloyl chloride and continue the reaction for 10 h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash, and dry to obtain chitosan antibacterial monomer. The mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3 g: 15 mL: 10 mL.

[0079] Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile, stirred until homogeneous, and then 3-chloro-2-chloromethylpropene was slowly added. After the addition was complete, the temperature was slowly raised to 70°C and the mixture was stirred for 18 hours. After the reaction was completed, the mixture was washed, filtered, and dried to obtain the quaternary phosphonium salt antibacterial monomer. The molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene was 1:1.05.

[0080] Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile were added to tetrahydrofuran, stirred until homogeneous, and refluxed at 75°C for 14 h. After the reaction was completed, the mixture was precipitated, washed, and dried to obtain a siloxane polymer. The molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane was 8.5:4.5:2.5:13; the azobisisobutyronitrile content was 0.025 wt% of the total reactants.

[0081] Step S5: Perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to ethylene glycol dimethyl ether. The mixture was slowly heated to 80°C, and hydrochloric acid was added to adjust the pH to 5. After stirring for 2.0 h, deionized water was added dropwise. After the addition was complete, the reaction continued for 8 h. The fluorosilicone resin was obtained by rotary evaporation of the solvent and dilution with anhydrous ethanol. The mass-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2 mL: 1.5 mL: 2 mL: 1.2 g: 1 mL: 1 mL: 1.25 mL.

[0082] Step 2: Anhydrous ethanol and 25 wt% ammonia were mixed and stirred at 35°C for 40 min. Tetraethyl orthosilicate was then added, and the reaction was continued for 3 h. After the reaction was complete, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate were added dropwise. Stirring was continued for 3.5 h after the addition was complete. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain silica filler. The reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane was 250:20:20:0.6; dibutyltin dilaurate accounted for 0.04 wt% of the total reactants.

[0083] 5g of 2-hydroxy-2-methyl-1-phenylpropanone and 20g of silica filler were added to 100g of fluorosilicone resin and stirred thoroughly for 50min to obtain a hydrophobic and oleophobic coating.

[0084] Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, and then spray a silica coating. After the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained.

[0085] Testing and experimentation:

[0086] Antimicrobial test: The coatings prepared in the examples / comparative examples were sprayed onto the surface of a glass slide according to the corresponding process to obtain samples. Escherichia coli cultured in the culture medium was diluted to obtain a concentration of 1×10⁻⁶. 6 The sample was immersed in the E. coli bacterial suspension at CFU / mL and incubated at 30°C for 12 hours. After incubation, the culture was transferred to a culture medium and incubated at 30°C for 24 hours. The colony count was calculated after incubation. A control group was set up, consisting of E. coli bacterial suspension without the sample. After the above incubation, the colony count was calculated. The corresponding data were then used to calculate the antibacterial rate.

[0087] Water contact angle: The coatings prepared in the examples / comparative examples were sprayed onto the surface of a glass slide according to the corresponding process to obtain a sample. The water contact angle of the sample surface was measured using a Chengde Dingsheng JY-82C video contact angle meter. 5 mL of deionized water was used as the titration volume each time to test the surface wettability of the sample. The test result was determined by the average of three measurements.

[0088] Oil contact angle: The coatings prepared in the examples / comparative examples were sprayed onto the surface of a glass slide according to the corresponding process to obtain samples. The oil contact angle of the sample surface was measured using a Chengde Dingsheng JY-82C video contact angle meter. 5 mL of n-hexadecane was used as the titration volume for each measurement to test the surface wettability of the sample. The test results were determined by the average of three measurements. The results are shown in the table below:

[0089]

[0090] Conclusion: In Examples 1-3, the dosage remained unchanged, with only some reaction parameters modified. Experimental data showed no significant fluctuations in the performance of the samples.

[0091] Comparative Example 1: The reaction mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane was adjusted to 2 mL:1 mL:1 mL:0.5 g:1 mL:1 mL, with the rest being the same as in Example 1. Experimental data showed that compared to Example 1, the antibacterial rate decreased to 91%, the water contact angle decreased to 145°, and the oil contact angle decreased to 137°. The reason for this is that the present invention incorporates perfluoro... The reaction mass ratio of octyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl dimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane is 2 mL: (1.4-1.6) mL: (1.8-2.2) mL: (1.0-1.3) g: 1 mL: 1 mL. Within this range, the prepared fluorosilicone resin has superior antibacterial and hydrophobic / oleophobic properties. Therefore, adjusting the ratio range to a smaller value results in a decrease in antibacterial rate, water contact angle, and oil contact angle.

[0092] Comparative Example 2: The reaction mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane was adjusted to 2 mL:2 mL:3 mL:2 g:1 mL:1 mL, with the rest remaining the same as in Example 1. Experimental data showed that compared to Example 1, the antibacterial rate decreased to 96%, the water contact angle decreased to 150°, and the oil contact angle decreased to 142°. The reason for this is that the present invention uses perfluorooctyltrimethoxysilane and heptadecafluorodecyl... The reaction mass ratio of trimethoxysilane, hydroxypropyl polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane is 2 mL : (1.4-1.6) mL : (1.8-2.2) mL : (1.0-1.3) g : 1 mL : 1 mL. Within this range, the prepared fluorosilicone resin has better antibacterial and hydrophobic / oleophobic properties. Therefore, when the ratio range is increased, there is a problem of incomplete reaction among the reactants and reduced reaction efficiency, resulting in a decrease in antibacterial rate, water contact angle, and oil contact angle.

[0093] Comparative Example 3: The siloxane polymer was removed, and the rest was the same as in Example 1. The experimental data showed that compared with Example 1, the antibacterial rate decreased to 71%, the water contact angle decreased to 139°, and the oil contact angle decreased to 131°. The reason for this is that the siloxane polymer also contains antibacterial materials such as quaternary ammonium salt and chitosan, so it has better antibacterial properties. In addition, the siloxane polymer also contains fluorine monomers with low surface energy. Therefore, after removing the siloxane polymer, the antibacterial rate, water contact angle and oil contact angle decreased.

[0094] Comparative Example 4: The silica coating was removed, and the rest remained the same as in Example 1. Experimental data showed that compared to Example 1, the antibacterial rate decreased to 87%, the water contact angle decreased to 132°, and the oil contact angle decreased to 124°. The reason for this is that the silica coating prepared in this invention contains fluorine groups. Therefore, when the silica filler is applied to the circuit board coating, fluorine atoms accumulate on the coating surface, forming a low surface energy fluoride layer. Furthermore, spraying the silica coating onto a cured hydrophobic and oleophobic coating allows the solvent to evaporate, forming a rough hydrophobic surface that further reduces surface energy. Therefore, removing the silica coating reduces the antibacterial rate, water contact angle, and oil contact angle.

[0095] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0096] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a hydrophobic and oleophobic circuit board for an e-liquid resistant microphone, characterized in that: Includes the following steps: Step 1: Add perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl-terminated polydimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane to ethylene glycol dimethyl ether. Slowly heat to 75-80℃ and add hydrochloric acid to adjust the pH to 4-5. Continue stirring for 1.5-2.0 hours, then add deionized water dropwise. After the addition is complete, continue the reaction for 7-8 hours. The solution is then removed by rotary evaporation of the solvent and anhydrous ethylene glycol dimethyl ether. The fluorosilicone resin was obtained by diluting with alcohol. The reaction mass-to-volume ratio of perfluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, hydroxypropyl dimethylsiloxane, siloxane polymer, tetraethyl orthosilicate, γ-methacryloyloxypropyltrimethoxysilane, and deionized water was 2 mL : (1.4-1.6) mL : (1.8-2.2) mL : (1.0-1.3) g : 1 mL : 1 mL : (1.2-1.3) mL. Step 2: Add 2-hydroxy-2-methyl-1-phenylpropanone and silica filler to fluorosilicone resin, and stir thoroughly for 30-50 minutes to obtain a hydrophobic and oleophobic coating; add silica filler to anhydrous ethanol, and ultrasonically disperse for 20-30 minutes to obtain a silica coating; the content of each component in the hydrophobic and oleophobic coating is as follows: by mass parts, 3-5 parts of 2-hydroxy-2-methyl-1-phenylpropanone, 15-20 parts of silica filler, and 90-100 parts of fluorosilicone resin; when preparing the silica coating, the mass-to-volume ratio of silica filler to anhydrous ethanol is 1 g: (8-10) mL; Step 3: Drill holes and clean the surface of the circuit board to obtain a circuit board with micropores on the surface; spray a hydrophobic and oleophobic coating onto the surface of the circuit board, cure it with ultraviolet light, then spray a silica coating, and after the solvent evaporates, the hydrophobic and oleophobic circuit board is obtained. The preparation process of siloxane polymers is as follows: Step S1: Add chitosan to deionized water, stir evenly, then add 2,3-epoxypropyltrimethylammonium chloride, and react at 80-85℃ for 14-15 hours. After the reaction is completed, the mixture is precipitated, aged, filtered, washed, purified, and dried to obtain modified chitosan. Step S2: Add modified chitosan to methanesulfonic acid, stir to dissolve, and then stir at 0-2℃ for 1.5-2.0h. After stirring, slowly add acryloyl chloride and continue the reaction for 8-10h. After the reaction is completed, precipitate, centrifuge, reprecipitate, wash and dry to obtain chitosan antibacterial monomer. Step S3: Under nitrogen atmosphere, tris(4-methoxyphenyl)phosphine was added to acetonitrile and stirred until homogeneous. Then, 3-chloro-2-chloromethylpropene was slowly added. After the addition was completed, the temperature was slowly raised to 60-70℃ and the mixture was stirred for 15-18 hours. After the reaction was completed, the mixture was washed, filtered and dried to obtain the quaternary phosphonium salt antibacterial monomer. Step S4: Trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, 3-mercaptopropyltriethoxysilane, and azobisisobutyronitrile are added to tetrahydrofuran, stirred evenly, and refluxed at 70-75℃ for 12-14h. After the reaction is completed, the product is precipitated, washed, and dried to obtain the siloxane polymer. The preparation process of silica filler is as follows: Anhydrous ethanol and 20-25 wt% ammonia water are mixed and stirred at 30-35℃ for 30-40 min. Then, tetraethyl orthosilicate is added and the reaction is continued for 2-3 h. After the reaction is completed, heptadecafluorodecyltrimethoxysilane and dibutyltin dilaurate are added dropwise. After the addition is completed, the mixture is stirred for 2.5-3.5 h. After the reaction is completed, the silica filler is obtained by centrifugation, washing and drying.

2. The method for preparing a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid according to claim 1, characterized in that: When preparing chitosan antibacterial monomers, the reaction mass ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride is 1:(4.0-4.5); the reaction mass-volume ratio of modified chitosan, methanesulfonic acid, and acryloyl chloride is 3g:15mL:(9-11)mL.

3. The method for preparing a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid according to claim 1, characterized in that: In step S3, the molar ratio of tris(4-methoxyphenyl)phosphine to 3-chloro-2-chloromethylpropene is 1:(1.0-1.1).

4. The method for preparing a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid according to claim 1, characterized in that: In step S4, the molar ratio of trifluoroethyl methacrylate, chitosan antibacterial monomer, quaternary phosphonium salt antibacterial monomer, and 3-mercaptopropyltriethoxysilane is (8-9):(4-5):(2-3):(12-14); the azobisisobutyronitrile is 0.02-0.03 wt% of the total mass of the reactants.

5. The method for preparing a hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid according to claim 1, characterized in that: When preparing silica filler, the reaction volume ratio of anhydrous ethanol, ammonia, tetraethyl orthosilicate, and heptadecafluorodecyltrimethoxysilane is 250:20:25:(0.5-0.7); the dibutyltin dilaurate is 0.03-0.05 wt% of the total mass of the reactants.

6. A hydrophobic and oleophobic circuit board for a microphone resistant to e-liquid, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

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