Methyl phenyl silicone resin and preparation method thereof

Abstract

The invention discloses a methyl phenyl silicone resin and a preparation method thereof, and belongs to the technical field of silicone resin, the preparation method comprises the following steps: carrying out staged heating on methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxy and fluorinated composite powder, carrying out hydrolysis and prepolymerization on the silane to form an oligomer, heating to 120 DEG C or above, carrying out reduced pressure condensation, and carrying out reduced pressure condensation to obtain the methyl phenyl silicone resin. In this way, the cross-linking density of a methyl phenyl silicone resin molecular chain can be more uniform through staged heating, silver nanowires and graphene oxide in the fluorinated composite powder have good heat conduction performance, the silver nanowires are loaded on the graphene oxide, a good heat conduction network is formed, heat can be conducted in the reaction process, and the heat conduction efficiency is improved. When the fluorinated composite powder is used as a coating of an outdoor electronic control element, heat can be conducted between molecular chains of the methyl phenyl silicone resin, heat diffusion is accelerated, too high local temperature is avoided, and meanwhile, a cage-shaped structure of aminated silsesquioxane in the fluorinated composite powder can limit movement of the molecular chains.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone resins, and specifically relates to a methylphenyl silicone resin and a preparation method thereof. Background Art

[0002] Silicone resin is a polyorganosiloxane with a main chain structure of -Si-O-Si-, a polymer with at least one organic group attached to the silicon atom, and exhibits a high degree of branching. The Si-O bond energy in the silicone resin backbone is high, combining the properties of both inorganic and organic materials. Therefore, under high-temperature conditions, the main chain silicon-oxygen bond energy of silicone resin is high, and the activation energy for chemical bond breakage is high, resulting in higher thermal stability and oxidation resistance than other organic polymers. Compared to other hydrocarbon polymers, silicone resin can maintain its initial physical properties over a wide temperature range, maintaining neither decomposition nor discoloration, even when used at higher temperatures (200-250°C). Silicone resin is not only heat-resistant, but also, after high-temperature ablation, a layer of inorganic silicon dioxide forms on its surface. Silicone dioxide is heat-resistant and can hinder the conduction of heat energy, thereby protecting the internal structure.

[0003] Chinese invention patent application publication number CN106750307B discloses a method for preparing methylphenyl silicone resin. The high-boiling-point ethylene glycol monomethyl ether obtained by hydrolysis of the silane monomer is used as the solvent for the polycondensation reaction, ensuring that the polycondensation reaction temperature is above 120°C. This not only avoids the production of acidic wastewater, but also eliminates the need to remove low-boiling-point byproducts and then add a high-boiling-point solvent, making it economical and environmentally friendly.

[0004] A Chinese invention patent application with publication number CN106047159B discloses a high-temperature resistant material based on silicone resin. By mixing silicone resin with other inorganic substances with different functions, these inorganic components and the silicone resin undergo physical adhesion and chemical molecular or atomic bonding at high temperatures. The material has high-temperature resistance that exceeds the temperature tolerance of existing silicone resins, overcoming the defect of silicone resin decomposition and performance failure at high temperatures.

[0005] However, the high-temperature one-step polycondensation in the above process may cause local excessive cross-linking of the molecular chain or residual oligomers, and the direct addition of inorganic components to the silicone resin will result in uneven distribution of inorganic substances in the silicone resin. When used as a coating in outdoor electronic control components, high-power chips will generate a large amount of heat when they continue to work. The heat generated during operation will intensify the movement of the molecular chains. If the cross-linking density of the molecular chains is uneven, the molecular chains will be broken faster, especially at the edges of the electronic component packaging, where cracks are prone to occur. The uneven distribution of inorganic components will result in uneven heat conduction, which will cause the local temperature of the coating to be too high and promote the generation of cracks. Summary of the Invention

[0006] The methyl phenyl silicone resin and the preparation method thereof, by polymerizing methyl trimethoxysilane, dimethyl dimethoxysilane, phenyl trimethoxysilane and fluorinated composite powder through staged temperature rising, crack generation is reduced, and good high-temperature impact resistance and oil-repellent performance are achieved.

[0007] The object of the present application can be achieved by the following technical solutions.

[0008] A preparation method of a methyl phenyl silicone resin comprises the following steps:

[0009] Step one: by nucleophilic substitution reaction, tris(2-aminoethyl)amine is grafted to octachloropropyl silesquioxane to obtain aminosiloxane, silver ions in silver nitrate solution are reduced to nano silver element and clustered into nucleation on graphene oxide to obtain a supported graphene powder, and the supported graphene powder and the aminosiloxane are connected together through amidation reaction to obtain a composite powder.

[0010] Step two: the composite powder is fluorinated by perfluorodecyl trimethoxysilane to obtain fluorinated composite powder with fluorine groups.

[0011] Step three: methyl trimethoxysilane, dimethyl dimethoxysilane, phenyl trimethoxysilane and the fluorinated composite powder are hydrolyzed and condensed to obtain a silicone resin prepolymer, and then subjected to vacuum condensation to obtain the methyl phenyl silicone resin.

[0012] Further, the preparation process of the aminosiloxane is as follows:

[0013] Octachloropropyl silesquioxane, tris(2-aminoethyl)amine, triethylamine and N,N'-dimethylformamide are added to a reaction kettle, and refluxed at 80-90 DEG C for 24-26 h, cooled to room temperature, washed, purified, dried to obtain the aminosiloxane.

[0014] Further, the amount ratio of octachloropropyl silesquioxane, tris(2-aminoethyl)amine, triethylamine and N,N'-dimethylformamide is 7.5-10 g:3.5-5 g:50-60 mL:150-200 mL.

[0015] Further, the preparation process of the supported graphene powder is as follows:

[0016] Polyvinyl pyrrolidone, graphene oxide powder with a diameter of 0.5-3 μm and ethylene glycol are added to a reactor, ultrasonically dispersed for 20-30 minutes, and then a 0.01 mol / L ferric chloride ethylene glycol solution is added and mixed evenly. A 0.1 mol / L silver nitrate solution is dropped into the reactor, and the reactor is sealed and reacted at 170-175° C. for 150-160 minutes. The reactor is cooled to room temperature, acetone is added, filtered, and washed to obtain supported graphene powder.

[0017] Furthermore, the usage ratio of polyvinyl pyrrolidone, graphene oxide powder, ethylene glycol, ferric chloride ethylene glycol solution and silver nitrate solution is 16-20 g: 15-21 g: 1-1.5 L: 10-15 mL: 1-1.5 L.

[0018] Furthermore, the preparation process of the composite powder is as follows:

[0019] The supported graphene powder and tetrahydrofuran are added to a reactor and ultrasonically dispersed. The aminosilsesquioxane and tetrahydrofuran are then mixed evenly and added to the reactor. The catalyst N,N-dicyclohexylcarbodiimide is added, and the mixture is refluxed at 70-80° C. and 500-700 r / min for 48-50 hours. The solution is washed and filtered, and the filter residue is collected to obtain a composite powder.

[0020] Furthermore, the mass ratio of the supported graphene powder, the aminosilsesquioxane and the catalyst N,N-dicyclohexylcarbodiimide is 10-12:150-200:10-12.

[0021] Furthermore, the preparation process of the fluorinated composite powder is as follows:

[0022] Anhydrous ethanol and composite powder are added to a reactor and ultrasonically dispersed. Then, sodium hydroxide, dimethyldimethoxysilane and n-octyltriethoxysilane are added to the reactor, and the mixture is reacted at 20-25° C. and 300-500 r / min for 30-40 minutes. Then, deionized water is dripped into the reactor, and the mixture is reacted at 65-75° C. for 24-26 hours. Then, perfluorodecyltrimethoxysilane is dripped into the reactor, filtered, washed, and dried to obtain a fluorinated composite powder.

[0023] Furthermore, the usage ratio of anhydrous ethanol, composite powder, sodium hydroxide, dimethyldimethoxysilane and n-octyltriethoxysilane, deionized water and perfluorodecyltrimethoxysilane is 2-3L: 10-15g: 20-25g: 90-15g: 220-300g: 50-60mL: 6-10g.

[0024] Further, the preparation process of methylphenyl silicone resin is as follows:

[0025] Methyl trimethoxysilane, dimethyl dimethoxysilane, phenyl trimethoxysilane, fluorinated composite powder and ethanol are added into a reaction kettle, stirred at 50-55 DEG C and 500-700 r / min for 30-40 min, pH value is adjusted to 3-4 by hydrochloric acid, heated to 65-70 DEG C, and then reacted for 4-5 h, separated, purified, distilled at 60-80 DEG C under reduced pressure, and then methyl phenyl silicone resin is obtained by adding the silicone resin prepolymer into the reaction kettle and condensing at 120-130 DEG C under reduced pressure for 1-2 h.

[0026] Further, the amount ratio of methyl trimethoxysilane, dimethyl dimethoxysilane, phenyl trimethoxysilane, fluorinated composite powder and ethanol is 43-50 g:77-90 g:31-37 g:10-15 g:23-30 L.

[0027] The present application has the following advantages:

[0028] 1、The methyl phenyl silicone resin in the present application is prepared by gradually heating methyl trimethoxysilane, dimethyl dimethoxysilane, phenyl trimethoxysilane and fluorinated composite powder, hydrolyzing and pre-polymerizing the silane to form oligomers, and then condensing at 120 DEG C or above under reduced pressure, so that the cross-linking density of the molecular chain of the methyl phenyl silicone resin is more uniform, which helps to reduce the generation of cracks and improve the effect of the methyl phenyl silicone resin in electronic packaging.

[0029] The silver nanowires and graphene oxide in the fluorinated composite powder have good thermal conductivity, the silver nanowires are loaded on the graphene oxide to form a good thermal conduction network, which not only conducts heat during the reaction to make the temperature distribution in the reaction kettle uniform, but also conducts heat between the molecular chains of the methyl phenyl silicone resin when used as a coating for outdoor electronic control elements, so as to accelerate the heat diffusion and avoid local overheating, and the cage structure of the aminosilsequioxane in the fluorinated composite powder can also limit the movement of the molecular chain, and the special spatial structure of the fluorinated composite powder can also dissipate thermal stress to reduce the generation of coating cracks during continuous operation, in addition, the introduction of the larger cage structure on the graphene oxide is conducive to avoiding the mutual adsorption and stacking of the graphene oxide nanosheets due to the van der Waals force, so that the graphene oxide nanosheets are more easily dispersed uniformly in the methyl phenyl silicone resin.

[0030] 2. In the present invention, silver nanowires are first generated on graphene oxide and then compounded with aminosilsesquioxane to obtain a composite powder. Silver ions in silver nitrate are reduced to elemental silver nanoparticles by ethylene glycol, and then nucleate and grow into silver nanowire structures on the graphene oxide. The layered structure of graphene oxide increases the specific surface area, which can perform multiple reflections of electromagnetic waves. The silver nanowires can also attenuate energy through surface reflection, extending the propagation path of electromagnetic waves. At the same time, the silver nanowires are loaded on the graphene oxide to form a continuous pathway, enhancing the reflection efficiency. The combination of the two can improve the electromagnetic shielding performance of methylphenyl silicone resin. When used in electronic control components, it can shield the interference of external electromagnetic waves on internal working components.

[0031] 3. In the present invention, the amino groups on the amino silsesquioxane and the carboxyl groups on the edge of the graphene oxide undergo an amidation reaction and are grafted together to form a composite powder, which is then grafted with perfluorodecyltrimethoxysilane to form a fluorinated composite powder. The fluorine atoms in the fluorinated composite powder have ultra-low surface energy, and their long-chain structure can form a dense fluorinated layer. The cage structure of the amino silsesquioxane can form nano-shaped protrusions on the surface of the fluorinated composite powder layer, increasing the contact angle with water and forming a superhydrophobic interface. The long-chain structure of perfluorodecyltrimethoxysilane can enhance the flexibility of the methylphenyl silicone resin. In addition, the cage structure of the amino silsesquioxane can increase the crosslinking density with the silane chain segment. The two can jointly enhance the impact resistance of the methylphenyl silicone resin. DETAILED DESCRIPTION

[0032] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Example 1: This example provides a methylphenyl silicone resin, which is prepared by the following steps:

[0034] S1: 8.7 g of octachloropropyl silsesquioxane, 4.2 g of tris(2-aminoethyl)amine, 55 mL of triethylamine and 175 mL of N,N'-dimethylformamide were added to a reactor and refluxed at 85°C for 25 h. A nucleophilic substitution reaction occurred between octachloropropyl silsesquioxane and tris(2-aminoethyl)amine to connect them. The mixture was cooled to room temperature and filtered. The precipitate was washed with tetrahydrofuran, methanol, chloroform and acetone, respectively, purified with ethanol using a Soxhlet extractor for 25 h, and vacuum dried at 75°C for 49 h to obtain amino silsesquioxane.

[0035] S2: 18 g of polyvinyl pyrrolidone, 18 g of graphene oxide powder with a diameter of 0.5-3 μm and 1.2 L of ethylene glycol were added to a reactor, ultrasonically dispersed for 25 minutes, and then 12 mL of 0.01 mol / L ferric chloride ethylene glycol solution was added and mixed evenly at 600 r / min. 1.2 L of 0.1 mol / L silver nitrate solution was dropped into the reactor, and the reaction was sealed at 172 ° C for 155 minutes. The silver ions were reduced to nanosilver element by ethylene glycol and clustered and nucleated on the graphene oxide to form nanowires. The reaction was cooled to room temperature, 5.5 L of acetone was added, centrifuged and filtered, and washed with acetone 3 times to obtain supported graphene powder.

[0036] S3: 11 g of supported graphene powder and 2.1 L of tetrahydrofuran were added to a reactor, ultrasonically dispersed for 35 minutes, 175 g of aminosilsesquioxane and 5.5 L of tetrahydrofuran were mixed evenly and added to the reactor, and then 11 g of N,N-dicyclohexylcarbodiimide as a catalyst was added. The mixture was refluxed at 75°C and 600 r / min for 49 hours. Under the action of the catalyst, the carboxyl group on the supported graphene powder and the amino group on the aminosilsesquioxane underwent amidation reaction to form an amide bond. The solution was washed with 21 L of anhydrous methanol and 5.5 L of tetrahydrofuran, and the solution was filtered with a 0.22 μm polyvinylidene fluoride membrane. The filter residue was collected to obtain a composite powder.

[0037] S4: Add 2.5L of anhydrous ethanol and 12.5g of composite powder into the reactor, ultrasonically disperse for 35 minutes, then add 22.5g of sodium hydroxide, 12g of dimethyldimethoxysilane and 260g of n-octyltriethoxysilane into the reactor, react at 22°C and 400r / min for 35 minutes, then drop 55mL of deionized water, react at 70°C for 25h, then drop 8g of perfluorodecyltrimethoxysilane, filter with a 0.22μm polytetrafluoroethylene membrane, wash the precipitate with distilled water until it is neutral, and dry to obtain a fluorinated composite powder.

[0038] S5: Add 46.5g of methyltrimethoxysilane, 83.5g of dimethyldimethoxysilane, 34g of phenyltrimethoxy, 12.5g of fluorinated composite powder and 26.5L of ethanol into a reactor, stir at 52°C and 600r / min for 35min, dropwise add 5mol / L hydrochloric acid aqueous solution into the reactor, adjust the pH value to 3, raise the temperature to 67°C, continue the reaction for 4.5h, let stand, separate, neutralize the organic phase repeatedly with 60°C distilled water 4 times, distill under reduced pressure at 70°C to remove ethanol and water to obtain a silicone resin prepolymer, add the silicone resin prepolymer into a reactor, and combine under reduced pressure at 125°C for 1.5h to obtain methylphenyl silicone resin.

[0039] Example 2: This example provides a methylphenyl silicone resin, which is prepared by the following steps:

[0040] S1: 7.5 g of octachloropropyl silsesquioxane, 3.5 g of tris(2-aminoethyl)amine, 50 mL of triethylamine and 150 mL of N,N'-dimethylformamide were added to a reactor and refluxed at 80°C for 24 h. A nucleophilic substitution reaction occurred between octachloropropyl silsesquioxane and tris(2-aminoethyl)amine to connect them. The mixture was cooled to room temperature and filtered. The precipitate was washed with tetrahydrofuran, methanol, chloroform and acetone, respectively, purified with ethanol using a Soxhlet extractor for 24 h, and vacuum dried at 70°C for 48 h to obtain amino silsesquioxane.

[0041] S2: 16 g of polyvinyl pyrrolidone, 15 g of graphene oxide powder with a diameter of 0.5-3 μm and 1 L of ethylene glycol were added to a reactor, ultrasonically dispersed for 20 minutes, and then 10 mL of 0.01 mol / L ferric chloride ethylene glycol solution was added and mixed evenly at 500 r / min. 1 L of 0.1 mol / L silver nitrate solution was dropped into the reactor, and the reaction was sealed at 170°C for 150 minutes. The silver ions were reduced to nanosilver by ethylene glycol and clustered to form nanowires on the graphene oxide. The reaction was cooled to room temperature, 5 L of acetone was added, centrifuged and filtered, and washed twice with acetone to obtain supported graphene powder.

[0042] S3: 10 g of supported graphene powder and 2 L of tetrahydrofuran were added to a reactor, ultrasonically dispersed for 30 minutes, 150 g of aminosilsesquioxane and 5 L of tetrahydrofuran were mixed evenly and added to the reactor, and then 10 g of N,N-dicyclohexylcarbodiimide as a catalyst was added. The mixture was refluxed at 70°C and 500 r / min for 48 hours. Under the action of the catalyst, the carboxyl group on the supported graphene powder and the amino group on the aminosilsesquioxane underwent amidation reaction to form an amide bond. The solution was washed with 20 L of anhydrous methanol and 5 L of tetrahydrofuran, and the solution was filtered with a 0.22 μm polyvinylidene fluoride membrane. The filter residue was collected to obtain a composite powder.

[0043] S4: Add 2L of anhydrous ethanol and 10g of composite powder into the reactor, ultrasonically disperse for 30 minutes, then add 20g of sodium hydroxide, 9g of dimethyldimethoxysilane and 220g of n-octyltriethoxysilane into the reactor, react at 20°C and 300r / min for 30 minutes, then drop 50mL of deionized water, react at 65°C for 24h, then drop 6g of perfluorodecyltrimethoxysilane, filter with a 0.22μm polytetrafluoroethylene membrane, wash the precipitate with distilled water until it is neutral, and dry to obtain a fluorinated composite powder.

[0044] S5: Add 43g of methyltrimethoxysilane, 77g of dimethyldimethoxysilane, 31g of phenyltrimethoxy, 10g of fluorinated composite powder and 23L of ethanol into a reactor, stir at 50°C and 500r / min for 30min, drop a 5mol / L hydrochloric acid aqueous solution into the reactor, adjust the pH value to 3, raise the temperature to 65°C, continue the reaction for 4h, let it stand, separate, neutralize the organic phase repeatedly with 60°C distilled water 3 times, distill under reduced pressure at 60°C to remove ethanol and water to obtain a silicone resin prepolymer, add the silicone resin prepolymer into a reactor, and combine under reduced pressure at 120°C for 1h to obtain methylphenyl silicone resin.

[0045] Example 3: This example provides a methylphenyl silicone resin, which is prepared by the following steps:

[0046] S1: 10 g of octachloropropyl silsesquioxane, 5 g of tris(2-aminoethyl)amine, 60 mL of triethylamine and 200 mL of N,N'-dimethylformamide were added to a reactor and refluxed at 90°C for 26 h. A nucleophilic substitution reaction occurred between octachloropropyl silsesquioxane and tris(2-aminoethyl)amine to connect them. The mixture was cooled to room temperature and filtered. The precipitate was washed with tetrahydrofuran, methanol, chloroform and acetone, respectively, purified with ethanol using a Soxhlet extractor for 26 h, and vacuum dried at 80°C for 50 h to obtain amino silsesquioxane.

[0047] S2: 20 g of polyvinyl pyrrolidone, 21 g of graphene oxide powder with a diameter of 0.5-3 μm and 1.5 L of ethylene glycol were added to a reactor, ultrasonically dispersed for 30 min, and then 15 mL of 0.01 mol / L ferric chloride ethylene glycol solution was added and mixed evenly at 700 r / min. 1.5 L of 0.1 mol / L silver nitrate solution was dropped into the reactor, and the reaction was sealed at 175 ° C for 160 min. The silver ions were reduced to nanosilver by ethylene glycol and clustered and nucleated on the graphene oxide to form nanowires. The reaction was cooled to room temperature, 6 L of acetone was added, centrifuged and filtered, and washed with acetone 4 times to obtain supported graphene powder.

[0048] S3: 12 g of supported graphene powder and 2.2 L of tetrahydrofuran were added to a reactor, ultrasonically dispersed for 40 min, 200 g of aminosilsesquioxane and 6 L of tetrahydrofuran were mixed evenly and added to the reactor, and then 12 g of N, N-dicyclohexylcarbodiimide as a catalyst was added. The mixture was refluxed at 80 ° C and 700 r / min for 50 h. Under the action of the catalyst, the carboxyl group on the supported graphene powder and the amino group on the aminosilsesquioxane underwent amidation reaction to form an amide bond. The solution was washed with 22 L of anhydrous methanol and 6 L of tetrahydrofuran, and the solution was filtered with a 0.22 μm polyvinylidene fluoride membrane. The filter residue was collected to obtain a composite powder.

[0049] S4: Add 3L of anhydrous ethanol and 15g of composite powder into the reactor, ultrasonically disperse for 40 minutes, then add 25g of sodium hydroxide, 15g of dimethyldimethoxysilane and 300g of n-octyltriethoxysilane into the reactor, react at 25°C and 500r / min for 40 minutes, then drop 60mL of deionized water, react at 75°C for 26h, then drop 10g of perfluorodecyltrimethoxysilane, filter with a 0.22μm polytetrafluoroethylene membrane, wash the precipitate with distilled water until it is neutral, and dry to obtain a fluorinated composite powder.

[0050] S5: Add 50g of methyltrimethoxysilane, 90g of dimethyldimethoxysilane, 37g of phenyltrimethoxy, 15g of fluorinated composite powder and 30L of ethanol into a reactor, stir at 55°C and 700r / min for 40min, drop a 5mol / L hydrochloric acid aqueous solution into the reactor, adjust the pH value to 4, raise the temperature to 70°C, continue the reaction for 5h, let it stand, separate, and repeatedly neutralize the organic phase with 60°C distilled water 5 times, distill under reduced pressure at 80°C to remove ethanol and water to obtain a silicone resin prepolymer, add the silicone resin prepolymer into a reactor, and combine under reduced pressure at 130°C for 2h to obtain methylphenyl silicone resin.

[0051] Comparative Example 1: Based on Example 1, the fluorinated composite powder was removed in step S5, and the remaining steps remained unchanged to prepare a methylphenyl silicone resin.

[0052] Comparative Example 2: Based on Example 1, commercially available graphene oxide powder (purchased from Zhongke Leiming Technology Co., Ltd.) was used instead of the supported graphene powder in step S3, and the remaining steps remained unchanged to prepare methylphenyl silicone resin.

[0053] Comparative Example 3: Based on Example 1, aminosilsesquioxane was removed from step S3, and the remaining steps remained unchanged to prepare methylphenyl silicone resin.

[0054] Comparative Example 4: Based on Example 1, the fluorinated composite powder was replaced by the composite powder prepared in step S3 in step S5, and the remaining steps remained unchanged to prepare a methylphenyl silicone resin.

[0055] The methylphenyl silicone resins prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to performance tests:

[0056] A certain amount of curing agent was weighed and added to the methylphenyl silicone resin solution, stirred evenly, and ultrasonicated for 1 hour. The components were weighed according to the laboratory's existing formula and mixed with the methylphenyl silicone resin. The resulting mixture was stirred for 1 hour and ultrasonicated for 1 hour to obtain a high-temperature resistant coating. The coating was poured into a polytetrafluoroethylene mold, and the room-temperature cured sample was tested. A tinplate sheet was selected as the substrate, and the oxide layer on the substrate surface was polished with 1000-grit sandpaper. The substrate was then cleaned with ethanol and dried for use. The coating was filtered through a fine gauze mesh and applied to the polished tinplate sheet substrate. After curing at room temperature, a high-temperature resistant coating was obtained.

[0057] Hydrophobicity: Observed using an SDC-100 contact angle meter manufactured by Dongguan Shengding Precision Instrument Co., Ltd. A trace amount of distilled water is dropped onto the coating surface and the contact angle is measured at multiple points, averaging the measured value. This testing method utilizes a combination of computer multimedia, an optical system, and a camera.

[0058] High temperature resistance: In order to explore the phase transition of methylphenyl silicone resin in a high temperature environment, the samples were placed in a BTF-1500C tubular furnace. The initial temperature was raised from room temperature to 400°C and 600°C at a heating rate of 10°C / min. Each sample was kept warm for 30 minutes. After being taken out, the surface morphology and volume shrinkage were observed to assess the high temperature resistance of the material. T5% represents the temperature at which the mass loss is 5%.

[0059] Linear Thermal Expansion Test (TMA): The cured resin sample was formed into a smooth cylinder with parallel upper and lower surfaces. The linear thermal expansion coefficient of the resin material was measured at 30-300°C using a thermal expansion analyzer (TMA 450) in a nitrogen atmosphere.

[0060] Impact resistance test: The impact resistance of the coating is measured in accordance with GB1732-79 "Determination of impact resistance of paint films". The test is conducted after cycling for 7 days at 100°C ± 5°C and 50% ± 5% relative humidity. The impact resistance of the coating refers to the degree of deformation of the coating under high-speed impact, which shows the elasticity of the tested coating.

[0061] Electromagnetic shielding performance test: The electromagnetic shielding performance of the coating samples was tested using the waveguide method using an Agilent Technologies E8362B vector network analyzer (VNA). The corresponding sample dimensions were 22.86 mm long, 10.16 mm wide, and 0.5 mm, 1.8 mm, and 2.3 mm thick. The electromagnetic parameters (reflection coefficient S 11 and absorption coefficient S 21) and use the formula to calculate the shielding parameters. R=|S 11 | 2 , T=|S 21 | 2 , A=1-RT,SE A =-101g[T / (1-R)], SE R =-101g(1-R), SE=SE A +SE R +SE M , where R, T and A represent the reflected power coefficient, transmitted power coefficient and absorbed power coefficient respectively. SE (shielding effectiveness) includes shielding effectiveness due to absorption (SEA), shielding effectiveness due to reflection (SER) and shielding effectiveness due to multiple reflection (SEM). When SE ≥ 10dB, SE M can be ignored. In addition, S 11 is the reflection coefficient of VNA port 1, S 21 is the forward transmission coefficient of the electromagnetic wave from port 1 to port 2 of the VNA. When the electromagnetic shielding material being tested is a homogeneous structure, S 11 =S 22 , S 21 =S 12 .

[0062] The test results are shown in the following table:

[0063] Table 1 Performance test list

[0064]

[0065] As can be seen from Table 1, the contact angles of Examples 1 to 3 are all greater than those of Comparative Example 1, Comparative Example 3, and Comparative Example 4. In step S5 of Comparative Example 1, the fluorinated composite powder is removed, and in step S3 of Comparative Example 3, the aminosilsesquioxane is removed. In step S5 of Comparative Example 4, the composite powder prepared in step S3 is used instead of the fluorinated composite powder, which shows that the aminosilsesquioxane and the fluorine chain segment can jointly improve the oil resistance of the methylphenyl silicone resin. This may be because the fluorine atoms contained in perfluorodecyltrimethoxysilane have ultra-low surface energy, and the cage structure of the aminosilsesquioxane forms nano-shaped protrusions, which increases the contact angle with water and forms a superhydrophobic interface.

[0066] The T5% in Examples 1 to 3 are all greater than those in Comparative Examples 1, 2, and 3. In step S5 of Comparative Example 1, the fluorinated composite powder is removed, in step S3 of Comparative Example 2, the supported graphene powder is replaced by commercially available graphene oxide powder, and in step S3 of Comparative Example 3, aminosilsesquioxane is removed, indicating that graphene oxide, silver nanowires, and aminosilsesquioxane can jointly improve the high temperature resistance of the methylphenyl silicone resin coating.

[0067] The linear thermal expansion coefficients in Examples 1 to 3 are all smaller than those in Comparative Examples 1 to 3. In step S5 of Comparative Example 1, the fluorinated composite powder is removed, in step S3 of Comparative Example 2, the supported graphene powder is replaced with commercially available graphene oxide powder, and in step S3 of Comparative Example 3, aminosilsesquioxane is removed. This shows that graphene oxide, silver nanowires, and aminosilsesquioxane can synergistically improve the high-temperature expansion resistance of methylphenyl silicone resin. This may be because graphene oxide and silver nanowires form a continuous thermal conductive network, which accelerates heat diffusion. In addition, the cage structure of aminosilsesquioxane reduces the mobility of the polymer chain segments, thereby inhibiting the expansion of the methylphenyl silicone resin coating at high temperatures.

[0068] The impact resistance of Examples 1 to 3 is greater than that of Comparative Example 1, Comparative Example 3 and Comparative Example 4. In step S5 of Comparative Example 1, the fluorinated composite powder is removed, and in step S3 of Comparative Example 3, the aminosilsesquioxane is removed. In step S5 of Comparative Example 4, the fluorinated composite powder is replaced by the composite powder prepared in step S3. This may be because the long-chain structure of perfluorodecyltrimethoxysilane can enhance the flexibility of the methylphenyl silicone resin, and the cage structure of the aminosilsesquioxane increases the crosslinking density between the fluorinated composite powder and the resin matrix, thereby making the high-temperature impact resistance of the methylphenyl silicone resin coating better.

[0069] The average shielding effectiveness in Examples 1 to 3 is greater than that in Comparative Examples 1 and 2. In step S5 of Comparative Example 1, the fluorinated composite powder is removed, and in step S3 of Comparative Example 2, commercially available graphene oxide powder is used instead of the supported graphene powder. This may be because the layered structure of graphene oxide increases the specific surface area, which can perform multiple reflections of electromagnetic waves. The silver nanowires can also attenuate energy through surface reflection. The two synergistically increase the electromagnetic shielding performance of the methylphenyl silicone resin coating.

[0070] It should be noted that, in this document, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0071] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a methylphenyl silicone resin, characterized in that: The steps include: Step 1: Grafting tris(2-aminoethyl)amine onto octachloropropylsilsesquioxane through a nucleophilic substitution reaction to obtain aminosilsesquioxane, reducing silver ions in a silver nitrate solution to elemental silver nanoparticles using ethylene glycol and clustering them on graphene oxide to obtain supported graphene powder, and linking the supported graphene powder and the aminosilsesquioxane through an amidation reaction to obtain a composite powder; Step 2: Fluorinating the composite powder with perfluorodecyltrimethoxysilane to obtain a fluorinated composite powder with fluorine groups; Step 3: hydrolyzing and condensing methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxy and fluorinated composite powder to obtain a silicone resin prepolymer, and then performing reduced pressure synthesis to obtain a methylphenyl silicone resin.

2. The method for preparing a methylphenyl silicone resin according to claim 1, wherein The preparation process of the aminosilsesquioxane in step 1 is as follows: Octachloropropylsilsesquioxane, tri(2-aminoethyl)amine, triethylamine and N,N'-dimethylformamide are added into a reaction kettle, refluxed at 80-90°C for 24-26h, cooled to room temperature, washed, purified and dried to obtain aminosilsesquioxane.

3. The method for preparing a methylphenyl silicone resin according to claim 2, wherein: The usage ratio of the octachloropropylsilsesquioxane, tris(2-aminoethyl)amine, triethylamine and N,N'-dimethylformamide is 7.5-10 g: 3.5-5 g: 50-60 mL: 150-200 mL.

4. The method for preparing a methylphenyl silicone resin according to claim 1, wherein The preparation process of the supported graphene powder in step 1 is as follows: Polyvinyl pyrrolidone, graphene oxide powder with a diameter of 0.5-3 μm, and ethylene glycol are added to a reactor, ultrasonically dispersed for 20-30 minutes, and then a 0.01 mol / L ferric chloride ethylene glycol solution is added and mixed evenly. A 0.1 mol / L silver nitrate solution is dripped into the reactor, and the reactor is sealed and reacted at 170-175° C. for 150-160 minutes. The reactor is cooled to room temperature, acetone is added, filtered, and washed to obtain supported graphene powder.

5. The method for preparing a methylphenyl silicone resin according to claim 4, wherein: The usage ratio of the polyvinyl pyrrolidone, graphene oxide powder, ethylene glycol, ferric chloride ethylene glycol solution and silver nitrate solution is 16-20 g: 15-21 g: 1-1.5 L: 10-15 mL: 1-1.5 L.

6. The method for preparing a methylphenyl silicone resin according to claim 1, wherein: The preparation process of the composite powder in step 1 is as follows: The supported graphene powder and tetrahydrofuran are added to a reactor and ultrasonically dispersed. The aminosilsesquioxane and tetrahydrofuran are then mixed evenly and added to the reactor. The catalyst N,N-dicyclohexylcarbodiimide is added, and the mixture is refluxed at 70-80° C. and 500-700 r / min for 48-50 hours. The solution is washed and filtered, and the filter residue is collected to obtain a composite powder.

7. The method for preparing a methylphenyl silicone resin according to claim 6, wherein: The mass ratio of the supported graphene powder, aminosilsesquioxane and catalyst N,N-dicyclohexylcarbodiimide is 10-12:150-200:10-12.

8. The method for preparing a methylphenyl silicone resin according to claim 1, wherein: The preparation process of the fluorinated composite powder in step 2 is as follows: Anhydrous ethanol and the composite powder are added to a reaction kettle, and ultrasonic dispersion is performed. Then, sodium hydroxide, dimethyldimethoxysilane and n-octyltriethoxysilane are added to the reaction kettle, and the mixture is reacted at 20-25° C. and 300-500 r / min for 30-40 minutes. Then, deionized water is added dropwise, and the mixture is reacted at 65-75° C. for 24-26 hours. Then, perfluorodecyltrimethoxysilane is added dropwise, and the mixture is filtered, washed, and dried to obtain a fluorinated composite powder. The usage ratio of the anhydrous ethanol, composite powder, sodium hydroxide, dimethyldimethoxysilane, n-octyltriethoxysilane, deionized water and perfluorodecyltrimethoxysilane is 2-3L: 10-15g: 20-25g: 90-15g: 220-300g: 50-60mL: 6-10g.

9. The method for preparing a methylphenyl silicone resin according to claim 1, wherein: The preparation process of the methylphenyl silicone resin described in step 3 is as follows: Methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxy, fluorinated composite powder and ethanol were added to a reaction kettle, stirred at 50-55°C and 500-700 r / min for 30-40 minutes, adjusted to a pH of 3-4 with hydrochloric acid, heated to 65-70°C, and reacted for 4-5 hours, allowed to stand, separated, purified, and distilled under reduced pressure at 60-80°C to obtain a silicone resin prepolymer. The silicone resin prepolymer was added to a reaction kettle, and compressed and combined at 120-130°C for 1-2 hours to obtain a methylphenyl silicone resin. The usage ratio of methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxy, fluorinated composite powder and ethanol is 43-50g: 77-90g: 31-37g: 10-15g: 23-30L.

10. A methylphenyl silicone resin, characterized in that The methylphenyl silicone resin is prepared by the preparation method of any one of claims 1 to 9.

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