Heat-conducting insulating silicone rubber as well as preparation method and application thereof

Abstract

The invention relates to the field of silicone rubber, and discloses heat-conducting and insulating silicone rubber as well as a preparation method and application thereof, the heat-conducting and insulating silicone rubber comprises silicone rubber, a modified composite nano filler, modified nano titanium dioxide and an auxiliary agent; the modified composite nanofiller is prepared by grafting an isocyanated composite nanofiller and a modified additive; the composite nanofiller is prepared by grafting aminated hexagonal boron nitride and graphene oxide; the modified additive is prepared by performing amination modification on a modified intermediate prepared by reacting cyanuric chloride with p-phenylenediamine by using ammonia water, and then reacting the modified intermediate with 3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride; the modified nano titanium dioxide is prepared by depositing a nano zinc borate sheet on the surface of nano titanium dioxide by using sodium tetraborate and zinc sulfate, then performing amination modification by using a silane coupling agent, and then grafting hyperbranched aromatic polyamide on the surface of the nano titanium dioxide. The material prepared by the invention has good mechanical properties, thermal conductivity, insulativity, flame retardance and aging resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of silicone rubber, and particularly relates to a heat-conducting insulating silicone rubber as well as a preparation method and application thereof. BACKGROUND

[0002] The heat-conducting insulating rubber is a kind of rubber-based composite material focusing on heat-conducting insulating performance, and is mostly based on silicone rubber, and has the characteristics of good elasticity, good electrical insulation, low pressure deformation, good sealing and the like. However, the existing heat-conducting insulating silicone rubber has low heat conductivity, and cannot meet the demand for high heat conductivity in power facilities. Hexagonal boron nitride has excellent electrical insulation performance, very low thermal expansion coefficient and high heat conductivity, and is widely used in polymer-based heat-conducting composites. However, the high chemical inertness of hexagonal boron nitride itself and the incompatibility with the polymer matrix make it difficult to process the composite material with good heat conductivity.

[0003] In addition, in order to make the silicone rubber achieve the characteristic of flame retardation, a large amount of inorganic flame-retardant filler is added, which will further reduce the heat conductivity of the material, and the excessive filler will seriously damage the continuity of the molecular chain, resulting in a sharp drop in mechanical properties, loss of elasticity, and affecting the application of the product. In addition, when the silicone rubber is used under harsh conditions such as high-intensity ultraviolet radiation and high-temperature environment, the silicone rubber will be affected by heat, ultraviolet radiation and oxygen, and the aging problems such as changes in mechanical properties and surface roughness will occur, thereby causing the deterioration or even loss of the use performance. SUMMARY

[0004] In order to solve the problems mentioned in the background, the purpose of the present application is to provide a heat-conducting insulating silicone rubber, a preparation method and application thereof. By adding modified composite nano-filler and modified nano-titanium dioxide, the material is endowed with good mechanical properties, heat-conducting insulation, flame retardation, high-temperature aging resistance and ultraviolet aging resistance.

[0005] The purpose of the present application can be achieved by the following technical solutions. A heat-conducting insulating silicone rubber comprises the following components by weight: 100 parts of silicone rubber, 10-15 parts of modified composite nano-filler, 2-5 parts of modified nano-titanium dioxide, 1-3 parts of vulcanizing agent and 0.1-1 part of lubricant. The modified composite nano-filler is prepared by subjecting a composite nano-filler to isocyanate ionization with toluene-2,4-diisocyanate and then subjecting the modified composite nano-filler to nucleophilic addition reaction with a modified additive; the composite nano-filler is prepared by using hexagonal boron nitride and urea as raw materials, ball-milling to synthesize aminated hexagonal boron nitride, and then subjecting the aminated hexagonal boron nitride to amidation reaction with graphene oxide; The modified additive is prepared by using cyanuric chloride and p-phenylenediamine to undergo nucleophilic substitution reaction to prepare a modified intermediate, then using ammonia to convert the chlorine atoms in the modified intermediate into amino groups to prepare an aminated modified intermediate, then using thionyl chloride to activate the carboxyl end of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid into an acyl chloride structure and then reacting with the aminated modified intermediate to prepare; The modified nano-titanium dioxide is prepared by using sodium tetraborate and zinc sulfate as raw materials to deposit nano-zinc borate sheets on the surface of nano-titanium dioxide, then using γ-aminopropyl triethoxysilane to amino-modify the deposited nano-titanium dioxide, and then using 3,5-diaminobenzoic acid as a raw material to graft hyperbranched polyarylamide into the amino groups in the amino-modified deposited nano-titanium dioxide under the action of a catalyst.

[0006] Preferably, the preparation method of the modified composite nano-filler comprises the following steps: A. Hexagonal boron nitride and urea are taken into a ball mill tank, deionized water and steel balls with diameters of 2, 5 and 10 mm are added, and then ball milling is carried out at a speed of 800-820 r / min for 6-8 h. After ball milling, centrifugal separation is carried out, the lower sediment is taken out and dried to prepare aminated hexagonal boron nitride; B. The aminated hexagonal boron nitride is taken and ultrasonically dispersed in deionized water, then continuously stirred with graphene oxide, a 10% mass fraction sodium carbonate solution is used to adjust the pH value of the system to 7-9, carbodiimide and N-hydroxysuccinimide are sequentially added, and continuous stirring is carried out for 4-5 h. After reaction, filtration, drying are carried out to prepare a composite nano-filler; C. The composite nano-filler is taken and ultrasonically dispersed in toluene, heated to 60-70℃ under nitrogen protection, then toluene-2,4-diisocyanate and dibutyltin dilaurate are added, and stirring is carried out for 8-10 h. After reaction, filtration, washing, drying are carried out to prepare an isocyanate-modified composite nano-filler; D. The isocyanate-modified composite nano-filler is taken and ultrasonically dispersed in toluene, then modified additives and triethylamine are added under nitrogen protection, and stirring is carried out at 55-70℃ for 20-24 h. After reaction, filtration, washing, drying are carried out to prepare a modified composite nano-filler.

[0007] Preferably, the preparation method of the modified additive in step D comprises the following steps: D1. Cyanuric chloride and dichloromethane are taken into a reactor, stirred and mixed uniformly, then a dichloromethane solution of p-phenylenediamine is added dropwise under ice bath conditions at 0-5℃, stirring is carried out for 2-4 h, and after reaction, filtration, recrystallization purification are carried out to prepare a modified intermediate; D2, take the modified intermediate and tetrahydrofuran in the reactor, stirring mixed uniform, placed in room temperature conditions dropwise add ammonia water, stirring reaction 8~12h, after reaction by suction filtration, concentration, recrystallization, preparation obtained amino modified intermediate; D3, take 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and trichloromethane in the reactor, heating to 45~60℃, slowly dropwise add distilled dichlorosulfoxide stirring reaction 4~6h, after reaction by rotary evaporation, drying, preparation obtained 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride; D4, take the amino modified intermediate, 4-diaminopyridine, triethylamine and tetrahydrofuran in the reactor, stirring mixed uniform, then slowly add 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride and tetrahydrofuran mixture, room temperature reaction 10~12h, then heating to 70~80℃ continue to react 10~12h, after reaction by filtration, washing, drying, preparation obtained modified additive.

[0008] Preferably, the molar ratio of cyanuric chloride and p-phenylenediamine is 2:1.

[0009] Preferably, the molar ratio of the amino modified intermediate and 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride is 1:3~3.1.

[0010] Preferably, the preparation method of the modified nano titanium dioxide comprises the following steps: (1) take the nano titanium dioxide ultrasonic dispersion in deionized water, then placed in 85~90℃ water bath stirring activation 0.5~1h, after activation add sodium tetraborate solution, stirring uniform continue to add zinc sulfate solution, reaction process by using sodium hydroxide solution to ensure the pH value of the reaction system is 8~10, after reaction by suction filtration, washing, drying, preparation obtained deposition type nano titanium dioxide; (2) take the γ-aminopropyl triethoxysilane, deionized water and anhydrous ethanol stirring mixed uniform, get hydrolysis liquid, take the deposition type nano titanium dioxide and anhydrous ethanol in the reactor stirring mixed, then add the hydrolysis liquid, placed in 60~70℃ and keep nitrogen atmosphere stirring reaction 5~7h, after reaction by centrifugation, washing, drying, preparation obtained amino deposition type nano titanium dioxide; (3) take the amino deposition type nano titanium dioxide, 3,5-diamino benzoic acid, pyridine and triphenyl phosphite dispersion in N-methyl pyrrolidone, heating to 75~80℃ and keep nitrogen atmosphere stirring reaction 5~6h, after reaction by centrifugation, washing, drying, preparation obtained modified nano titanium dioxide.

[0011] Preferably, the concentration of the sodium tetraborate solution is 0.2-0.3 mol / L; the concentration of the zinc sulfate solution is 0.2-0.3 mol / L; the addition ratio of the nano-titanium dioxide, the sodium tetraborate solution and the zinc sulfate solution is 7-8 g: 20 mL: 40 mL.

[0012] Preferably, the mass ratio of the amino-deposited nano-titanium dioxide and 3,5-diamino benzoic acid is 10-14: 1.

[0013] The preparation method of the heat-conducting insulating silicone rubber as described above comprises the following steps: weighing each component by weight parts, mixing the silicone rubber, the modified composite nano-filler, the modified nano-titanium dioxide and the lubricant for 3-5 min, then adding the vulcanizing agent to mix uniformly and then vulcanizing at 120-160 DEG C for 5-8 min to prepare the heat-conducting insulating silicone rubber. The vulcanizing agent is one or more of bis-dipentasulfur, di-tert-butyl peroxide, benzoyl peroxide, dicumyl peroxide and cyclohexanone peroxide; and the lubricant is one or more of stearic acid, polyethylene wax and oxidized polyethylene wax.

[0014] The heat-conducting insulating silicone rubber as described above is applied to heat-conducting silicone rubber sheets, microelectronic devices or power cable materials.

[0015] The present application has the following advantages: The present application uses hexagonal boron nitride and urea as raw materials, and synthesizes amino-hexagonal boron nitride by using a ball milling method, and in the presence of a carboxyl activating agent, an amide reaction occurs between the carboxyl groups on the graphene oxide and the amino-hexagonal boron nitride, to prepare a composite nano-filler, wherein the graphene oxide has a large number of active groups (carboxyl and hydroxyl groups) and good mechanical properties and insulation, and the hexagonal boron nitride has the advantages of low cost, peelability, high thermal stability, good electrical insulation, etc. The present application covalently combines the hexagonal boron nitride and the graphene oxide to reduce the oxygen content in the graphene oxide and improve its thermal conductivity, and then combines the insulation of the hexagonal boron nitride to prepare a composite nano-filler with both thermal conductivity and insulation properties. Then, the composite nano-filler is treated with toluene-2,4-diisocyanate to make the isocyanate-treated composite nano-filler undergo a nucleophilic addition reaction with a modified additive to prepare a modified composite nano-filler.

[0016] The present application utilizes two molecules of cyanuric chloride to respectively undergo nucleophilic substitution reaction with the amino groups at both ends of the antioxidant p-phenylenediamine, to prepare a modified intermediate containing a triazine ring and an antioxidant functional group -NH, then converts the chlorine atoms in the modified intermediate into amino groups by using ammonia, to prepare an aminated modified intermediate, then activates the carboxyl end of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid into an acyl chloride structure by using dichlorosulfoxide, and then reacts with the aminated modified intermediate, to prepare a modified additive, which introduces multiple antioxidant hindered phenol structures, antioxidant functional groups, and triazine rings with good thermal stability and ultraviolet absorption, and utilizes the remaining amino group in the structure of the modified additive to undergo nucleophilic addition reaction with isocyanate-modified composite nano filler to prepare a modified composite nano filler, so that the modified additive is grafted on the surface of the composite nano filler through a firm chemical bond, to endow the material with long-term high-temperature aging resistance and ultraviolet aging resistance, and the grafting reaction is conducive to promoting the relatively uniform dispersion of the composite nano filler in the matrix material, to endow the material with more excellent mechanical properties, thermal conductivity and insulation properties.

[0017] The present application utilizes sodium tetraborate and zinc sulfate as raw materials to generate nanometer zinc borate sheets on the surface of nanometer titanium dioxide by a heterogeneous deposition method, to prepare a deposition type nanometer titanium dioxide, wherein titanium dioxide is an important inorganic ultraviolet shielding agent with certain ultraviolet shielding and absorption effects, and zinc borate can be thermally decomposed to produce molten boron oxide covering the surface of the polymer material during the combustion process of the matrix material, and the zinc ions in zinc borate can promote the crosslinking of the molecular chains of the polymer material into carbon, to endow the material with good flame retardance, then the silicon hydroxyl groups in gamma-aminopropyl triethoxysilane are hydrolyzed and grafted on the surface of the deposition type nanometer titanium dioxide, to prepare aminated deposition type nanometer titanium dioxide, and 3,5-diaminobenzoic acid is used as a raw material to graft hyperbranched polyarylamide through the amino groups in the aminated deposition type nanometer titanium dioxide under the action of a catalyst pyridine and triphenyl phosphite, to prepare modified nanometer titanium dioxide, wherein the grafting of hyperbranched polyarylamide is conducive to improving the dispersion uniformity of the deposition type nanometer titanium dioxide, to make it better play an effective performance, and the terminal amino groups of the hyperbranched polyarylamide can be combined with the surface of the modified composite nano filler through covalent bonds or strong hydrogen bonds, to significantly reduce the interfacial thermal resistance, and the hyperbranched structure acts as a dispersant and an interface bridge to construct an efficient heat conduction path, in addition, the hyperbranched polyarylamide has high insulation performance, to endow the material with good thermal conductivity and insulation. DETAILED DESCRIPTION

[0018] With reference to the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0019] Embodiment 1 A preparation method of a modified additive comprises the following steps: D1, 3.7g of cyanuric chloride and 30mL of dichloromethane were taken into a reactor, stirred and uniformly mixed, and then 1.1g of p-phenylenediamine was added dropwise in 5mL of dichloromethane under the condition of 0℃ ice bath, and stirred and reacted for 3h. After the reaction was completed, the modified intermediate was prepared by filtration, recrystallization and purification. D2, 4g of the modified intermediate and 20mL of tetrahydrofuran were taken into a reactor, stirred and uniformly mixed, and then 10mL of ammonia water was added dropwise under the condition of room temperature, and stirred and reacted for 12h. After the reaction was completed, the amino-modified intermediate was prepared by filtration, concentration and recrystallization. D3, 2.8g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and 30mL of dichloromethane were taken into a reactor, heated to 50℃, and then 2mL of distilled dichloro sulfoxide was slowly added dropwise, and stirred and reacted for 5h. After the reaction was completed, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride was prepared by rotary evaporation and drying. D4, 3.5g of the amino-modified intermediate, 0.2g of 4-diaminopyridine, 2g of triethylamine and 50mL of tetrahydrofuran were taken into a reactor, stirred and uniformly mixed, and then 9.8g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride and 100mL of tetrahydrofuran were slowly added dropwise, and reacted for 12h at room temperature, and then the temperature was increased to 75℃ and the reaction was continued for 12h. After the reaction was completed, the modified additive was prepared by filtration, washing and drying.

[0020] Embodiment 2 A preparation method of a modified composite nano filler comprises the following steps: A, 2g of hexagonal boron nitride and 100g of urea were taken into a ball mill tank, 150mL of deionized water and steel balls with diameters of 2, 5 and 10mm (the number ratio was 4:2:1) were added, and then the ball milling was carried out at a speed of 800r / min for 8h. After the ball milling was completed, the lower sediment was separated by centrifugation and dried to prepare the amino-modified hexagonal boron nitride. B, take 2g graphene oxide ultrasonic dispersion in 250mL deionized water, then add 4g amino hexagonal boron nitride continuous stirring, using mass fraction of 10% sodium carbonate solution to adjust the pH value of the system is 8, in turn add 0.8g carbodiimide and 1g N-hydroxysuccinimide, continuous stirring reaction 4h, after reaction by suction filtration, drying, preparation of composite nanofiller; C, take 5g composite nanofiller ultrasonic dispersion in 200mL toluene, under nitrogen protection to 65℃, then add 25g toluene-2, 4-diisocyanate and 3 drops of dibutyltin dilaurate, stirring reaction 10h, after reaction by suction filtration, washing, drying, preparation of isocyanate composite nanofiller; D, take 5g isocyanate composite nanofiller ultrasonic dispersion in 200mL toluene, under nitrogen protection to add 2.7g prepared in example 1 modifier additive and 0.3g triethylamine, placed in 65℃ stirring reaction 24h, after reaction by suction filtration, washing, drying, preparation of modified composite nanofiller.

[0021] Example 3 A method for preparing modified nanometer titanium dioxide comprises the following steps: (1) take 7.2g nanometer titanium dioxide ultrasonic dispersion in 20mL deionized water, then placed in 90℃ water bath stirring activation 1h, after activation add 20mL concentration of 0.25mol / L sodium tetraborate solution, stirring uniform after continue to add 40mL concentration of 0.25mol / L zinc sulfate solution, reaction process by using sodium hydroxide solution to ensure the pH value of the reaction system is 9, after reaction by suction filtration, washing, drying, preparation of deposition type nanometer titanium dioxide; (2) take volume ratio of 2:1:7 of γ-aminopropyl triethoxysilane, deionized water and anhydrous ethanol stirring mixed uniform, get hydrolysis liquid, take 5g deposition type nanometer titanium dioxide and 20mL anhydrous ethanol in the reactor stirring mixed, then add 100mL hydrolysis liquid, placed in 65℃ and keep nitrogen atmosphere stirring reaction 6h, after reaction by centrifugation, washing, drying, preparation of aminated deposition type nanometer titanium dioxide; (3) take 5g aminated deposition type nanometer titanium dioxide, 0.4g 3, 5-diamino benzoic acid, 4mL pyridine and 4mL triphenyl phosphite dispersion in 120mL N-methyl pyrrolidone, heating to 80℃ and keep nitrogen atmosphere stirring reaction 5h, after reaction by centrifugation, washing, drying, preparation of modified nanometer titanium dioxide.

[0022] Example 4 A kind of heat-conducting insulating silicone rubber, including the following weight parts components: silicone rubber 100 parts, modified composite nano filler 10.2 parts prepared in example 2, modified nanometer titanium dioxide 2.3 parts prepared in example 3, double two five vulcanizing agent 1.2 parts, lubricant stearic acid 0.2 parts.

[0023] The preparation method of the above-mentioned heat-conducting insulating silicone rubber includes the following steps: weighing each component by weight parts, mixing silicone rubber, modified composite nano filler, modified nanometer titanium dioxide and lubricant for 4 min, then adding vulcanizing agent and mixing uniformly, and then placing it at 140 DEG C for 6 min to vulcanize, to prepare the heat-conducting insulating silicone rubber.

[0024] Example 5 A kind of heat-conducting insulating silicone rubber, including the following weight parts components: silicone rubber 100 parts, modified composite nano filler 12.5 parts prepared in example 2, modified nanometer titanium dioxide 3.4 parts prepared in example 3, double two five vulcanizing agent 2.1 parts, lubricant polyethylene wax 0.6 parts.

[0025] The preparation method of the above-mentioned heat-conducting insulating silicone rubber is the same as example 4.

[0026] Example 6 A kind of heat-conducting insulating silicone rubber, including the following weight parts components: silicone rubber 100 parts, modified composite nano filler 14.7 parts prepared in example 2, modified nanometer titanium dioxide 4.8 parts prepared in example 3, double two five vulcanizing agent 2.7 parts, lubricant oxidized polyethylene wax 0.8 parts.

[0027] The preparation method of the above-mentioned heat-conducting insulating silicone rubber is the same as example 4.

[0028] Comparative example 1 A preparation method of modified composite nano filler includes the following steps: A, take 2g hexagonal boron nitride and 100g urea into a ball mill tank, add 150mL deionized water and steel balls with diameters of 2, 5 and 10mm (the number ratio is 4:2:1), then ball mill at a speed of 800r / min for 8h, after ball milling, centrifugal separation, take the lower sediment and dry, to prepare amino hexagonal boron nitride; B, take 2g graphene oxide and ultrasonically disperse it in 250mL deionized water, then continuously stir 4g amino hexagonal boron nitride, use 10% mass fraction sodium carbonate solution to adjust the pH value of the system to 8, add 0.8g carbodiimide and 1g N-hydroxysuccinimide in turn, continuously stir for 4h, after reaction, filter and dry, to prepare composite nano filler; C. 5 g of the composite nanofiller was ultrasonically dispersed in 200 mL of toluene, and then 25 g of toluene-2, 4-diisocyanate and 3 drops of dibutyltin dilaurate were added under nitrogen protection, and the mixture was stirred for 10 h. After the reaction was completed, the product was prepared by filtration, washing and drying. D. 5 g of the isocyanate-modified composite nanofiller was ultrasonically dispersed in 200 mL of toluene, and then 2.7 g of the amino-modified intermediate prepared in Example 1 and 0.3 g of triethylamine were added under nitrogen protection, and the mixture was stirred for 24 h at 65°C. After the reaction was completed, the product was prepared by filtration, washing and drying.

[0029] Comparative Example 2 A method for preparing a modified nanometer titanium dioxide includes the following steps: (1) γ-aminopropyltriethoxysilane, deionized water and anhydrous ethanol were mixed in a volume ratio of 2:1:7 to obtain a hydrolysis solution. 5 g of nanometer titanium dioxide and 20 mL of anhydrous ethanol were stirred and mixed in a reactor, and then 100 mL of the hydrolysis solution was added. The mixture was stirred at 65°C under nitrogen atmosphere for 6 h. After the reaction was completed, the product was prepared by centrifugation, washing and drying to obtain amino-modified nanometer titanium dioxide. (2) 5 g of the amino-modified nanometer titanium dioxide, 0.4 g of 3, 5-diaminobenzoic acid, 4 mL of pyridine and 4 mL of triphenyl phosphite were dispersed in 120 mL of N-methyl pyrrolidone, and the mixture was heated to 80°C and stirred for 5 h under nitrogen atmosphere. After the reaction was completed, the product was prepared by centrifugation, washing and drying to obtain modified nanometer titanium dioxide.

[0030] Comparative Example 3 A heat-conducting and insulating silicone rubber includes the following components by weight: 100 parts of silicone rubber, 14.7 parts of the modified composite nanofiller prepared in Comparative Example 1, 4.8 parts of the modified nanometer titanium dioxide prepared in Example 3, 2.7 parts of bis-dipentasulfurized disulfide, and 0.8 parts of lubricant oxidized polyethylene wax.

[0031] The preparation method of the heat-conducting and insulating silicone rubber is the same as that of Example 4.

[0032] Comparative Example 4 A heat-conducting and insulating silicone rubber includes the following components by weight: 100 parts of silicone rubber, 14.7 parts of the composite nanofiller prepared in Example 2, 4.8 parts of the modified nanometer titanium dioxide prepared in Example 3, 2.7 parts of bis-dipentasulfurized disulfide, and 0.8 parts of lubricant oxidized polyethylene wax.

[0033] The preparation method of the heat-conducting and insulating silicone rubber is the same as that of Example 4.

[0034] Comparative Example 5 A heat conductive and insulating silicone rubber comprises the following components by weight: 100 parts of silicone rubber, 14.7 parts of modified composite nano-filler prepared in Example 2, 4.8 parts of modified nano-titanium dioxide prepared in Comparative Example 2, 2.7 parts of bis-diphenyl disulfide vulcanizing agent, and 0.8 parts of lubricant oxidized polyethylene wax.

[0035] The heat conductive and insulating silicone rubber is prepared according to the method of Example 4.

[0036] Comparative Example 6 A heat conductive and insulating silicone rubber comprises the following components by weight: 100 parts of silicone rubber, 14.7 parts of modified composite nano-filler prepared in Example 2, 4.8 parts of nano-titanium dioxide, 2.7 parts of bis-diphenyl disulfide vulcanizing agent, and 0.8 parts of lubricant oxidized polyethylene wax.

[0037] The heat conductive and insulating silicone rubber is prepared according to the method of Example 4.

[0038] Performance testing The silicone rubber materials prepared in Examples 4-6 and Comparative Examples 3-6 are subjected to performance testing: (1) Mechanical properties and aging resistance testing: the tensile strength and elongation at break are tested according to GB / T 528-2009, the speed of the clamps during the tensile test is 500 mm / min; the change rate of the tensile strength and elongation at break after aging in a 110℃ heat aging oven for 168 h is tested, which is used to evaluate the high-temperature aging resistance of the sample; the change rate of the tensile strength and elongation at break after cumulative irradiation for 72 h under a 40W ultraviolet lamp at 60℃ is tested, the sample is 254 mm away from the lamp, which is used to evaluate the ultraviolet aging resistance of the sample, and the data results are shown in Table 1.

[0039] Table 1 Results of mechanical properties and aging resistance testing of samples

[0040] From the data results in Table 1, it can be seen that the silicone rubber materials prepared in Examples 4-6 and Comparative Example 5 of the present application have good mechanical properties, and still maintain high tensile strength and elongation at break after high temperature aging and ultraviolet aging, and have excellent aging resistance. Among them, the modified composite nano filler added in Comparative Example 3 uses an amino-modified intermediate to replace the modification additive, and the change rates of tensile strength and elongation at break after high temperature aging are obviously different from those of Examples 4-6, which is because the hindered phenol antioxidant structure is not introduced, resulting in a decrease in high temperature aging resistance of the material. In Comparative Example 4, the composite nano filler is directly added without using a modified additive to graft the composite nano filler, and the mechanical properties are lower than those of Examples 4-6, and the change rates of tensile strength and elongation at break after high temperature aging and ultraviolet aging are obviously different from those of Examples 4-6, which is because the poor compatibility between the composite nano filler and the matrix leads to a decrease in mechanical properties, and because the anti-aging functional groups, hindered phenol antioxidant structure and triazine ring structure are not introduced, resulting in a decrease in aging resistance. In Comparative Example 6, the nano titanium dioxide is not modified, and the mechanical properties are lower than those of Examples 4-6, and the change rates of tensile strength and elongation at break after ultraviolet aging are obviously different from those of Examples 4-6, which is because the agglomeration of nano titanium dioxide leads to a decrease in mechanical properties and ultraviolet aging resistance.

[0041] (2) Thermal conductivity test: The thermal conductivity test was carried out according to GB / T 22588-2008, and the data results are shown in Table 2.

[0042] (3) Volume resistivity test: The test was carried out according to IEC62631-3-1, and the sample was a disc with a diameter of 100 mm and a thickness of 2 mm, and the data results are shown in Table 2.

[0043] (4) Flame retardant performance test: The limiting oxygen index test was used, and the sample size was 130x6.5x3.2mm 3 , and the data results are shown in Table 2.

[0044] Table 2 Test results of thermal insulation and flame retardant properties of samples

[0045] From the data results in Table 2, it can be seen that the silicone rubber materials prepared in Examples 4-6 and Comparative Example 3 have good thermal insulation and flame retardant properties. The thermal conductivity, volume resistivity and limiting oxygen index of Comparative Example 4 are lower than those of Examples 4-6, because the composite nano filler agglomerates, the insulation performance is poor, and the filler particles cannot form a smooth heat conduction path, resulting in a decrease in thermal conductivity. In addition, the flame-retardant nitrogen elements in the triazine ring can improve the flame-retardant performance of the material to a certain extent. The modified nano titanium dioxide added in Comparative Example 5 is not deposited with zinc borate nanosheets, and the limiting oxygen index is significantly lower than that of Examples 4-6, indicating that the deposition of zinc borate is beneficial to improving the flame-retardant performance of the material. The thermal conductivity and volume resistivity of Comparative Example 6 are significantly lower than those of Examples 4-6, indicating that the grafting of hyperbranched polyarylamide is beneficial to further improving the thermal insulation of the material.

[0046] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0047] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A heat conductive insulating silicone rubber, characterized by, The components include the following weight parts: 100 parts of silicone rubber, 10-15 parts of modified composite nano filler, 2-5 parts of modified nano titanium dioxide, 1-3 parts of vulcanizing agent, 0.1-1 part of lubricant; The modified composite nano filler is prepared by isocyanating the composite nano filler with toluene-2,4-diisocyanate and then performing nucleophilic addition reaction with a modified additive; the composite nano filler is prepared by using hexagonal boron nitride and urea as raw materials, preparing aminoized hexagonal boron nitride by ball milling, and then performing amidation reaction with graphene oxide and the aminoized hexagonal boron nitride; The modified additive is prepared by performing nucleophilic substitution reaction with cyanuric chloride and p-phenylenediamine to prepare a modified intermediate, then converting chlorine atoms in the modified intermediate into amino groups by using ammonia water to prepare an aminoized modified intermediate, and then activating carboxyl at one end of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid into an acyl chloride structure by using dichlorosulfoxide and then reacting with the aminoized modified intermediate; The modified nano titanium dioxide is prepared by using sodium tetraborate and zinc sulfate as raw materials to deposit nano zinc borate sheets on the surface of nano titanium dioxide, then aminoizing the deposited nano titanium dioxide by using gamma-aminopropyltriethoxysilane, and then grafting hyperbranched polyarylamide through the amino groups in the aminoized deposited nano titanium dioxide under the action of a catalyst by using 3,5-diaminobenzoic acid as raw material.

2. The heat conductive insulating silicone rubber according to claim 1, characterized in that, The preparation method of the modified composite nano filler comprises the following steps: A. Put hexagonal boron nitride and urea into a ball mill tank, add deionized water and steel balls with diameters of 2, 5 and 10 mm, then ball mill at a speed of 800-820 r / min for 6-8 h, centrifuge after ball milling, take the lower sediment, and dry to prepare aminoized hexagonal boron nitride; B. Ultrasonically disperse graphene oxide in deionized water, then continuously stir in the aminoized hexagonal boron nitride, adjust the pH value of the system to 7-9 by using 10% sodium carbonate solution, add carbodiimide and N-hydroxysuccinimide in sequence, continuously stir for 4-5 h, then after reaction, perform suction filtration and drying to prepare the composite nano filler; C. Ultrasonically disperse the composite nano filler in toluene, heat to 60-70℃ under nitrogen protection, then add toluene-2,4-diisocyanate and dibutyltin dilaurate, stir for 8-10 h, then after reaction, perform suction filtration, washing and drying to prepare the isocyanated composite nano filler; D. Ultrasonically disperse the isocyanated composite nano filler in toluene, add the modified additive and triethylamine under nitrogen protection, stir at 55-70℃ for 20-24 h, then after reaction, perform suction filtration, washing and drying to prepare the modified composite nano filler.

3. The heat conductive insulating silicone rubber according to claim 2, characterized in that, The preparation method of the modified additive in step D comprises the following steps: D1. Put cyanuric chloride and dichloromethane in a reactor, stir to mix uniformly, add a dichloromethane solution of p-phenylenediamine dropwise under ice bath conditions at 0-5℃, stir for 2-4 h, then after reaction, perform suction filtration and recrystallization purification to prepare the modified intermediate; D2, take the modified intermediate and tetrahydrofuran in the reactor, stirring mixed uniform, placed in room temperature condition dropwise add ammonia water, stirring reaction 8~12h, after reaction by suction filtration, concentration, recrystallization, preparation obtained amino modified intermediate; D3, take 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and trichloromethane in the reactor, heating to 45~60℃, slowly dropwise add distilled dichlorosulfoxide stirring reaction 4~6h, after reaction by rotary evaporation, drying, preparation obtained 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride; D4, take the amino modified intermediate, 4-diaminopyridine, triethylamine and tetrahydrofuran in the reactor, stirring mixed uniform, then slowly add 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride and tetrahydrofuran mixture, room temperature reaction 10~12h, then heating to 70~80℃ continue to react 10~12h, after reaction by filtration, washing, drying, preparation obtained modified additive.

4. The heat conductive insulating silicone rubber according to claim 3, characterized in that, The molar ratio of cyanuric chloride and p-phenylenediamine is 2:

1.

5. The heat conductive insulating silicone rubber according to claim 3, characterized in that, The molar ratio of the amino modified intermediate and 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride is 1:3~3.

1.

6. The thermally conductive insulating silicone rubber of claim 1, wherein, The preparation method of the modified nano titanium dioxide comprises the following steps: (1) take the nano titanium dioxide ultrasonic dispersion in deionized water, then placed in 85~90℃ water bath stirring activation 0.5~1h, after activation add sodium tetraborate solution, stirring uniform continue to add zinc sulfate solution, reaction process by using sodium hydroxide solution to ensure the pH value of the reaction system is 8~10, after reaction by suction filtration, washing, drying, preparation obtained deposition type nano titanium dioxide; (2) take the γ-aminopropyl triethoxysilane, deionized water and anhydrous ethanol stirring mixed uniform, get hydrolysis liquid, take the deposition type nano titanium dioxide and anhydrous ethanol in the reactor stirring mixed, then add hydrolysis liquid, placed in 60~70℃ and keep nitrogen atmosphere stirring reaction 5~7h, after reaction by centrifugation, washing, drying, preparation obtained amino deposition type nano titanium dioxide; (3) take the amino deposition type nano titanium dioxide, 3,5-diaminobenzoic acid, pyridine and triphenyl phosphite dispersion in N-methyl pyrrolidone, heating to 75~80℃ and keep nitrogen atmosphere stirring reaction 5~6h, after reaction by centrifugation, washing, drying, preparation obtained modified nano titanium dioxide.

7. The heat conductive insulating silicone rubber according to claim 6, characterized in that, The concentration of the sodium tetraborate solution is 0.2~0.3mol / L; the concentration of the zinc sulfate solution is 0.2~0.3mol / L; the addition ratio of the nano titanium dioxide, sodium tetraborate solution and zinc sulfate solution is 7~8g:20mL:40mL.

8. The heat conductive insulating silicone rubber according to claim 6, characterized in that, The mass ratio of the amino deposition type nano titanium dioxide and 3,5-diaminobenzoic acid is 10~14:

1.

9. A process for the production of the heat-conducting, electrically insulating silicone rubber according to any one of claims 1 to 8, characterized in that Comprise the following steps: According to the weight part, the components are weighed, the silicone rubber, the modified composite nano filler, the modified nano titanium dioxide and the lubricant are mixed for 3~5min, then the vulcanizing agent is added and mixed uniformly, and then vulcanized at 120~160℃ for 5~8min to prepare the heat-conducting insulating silicone rubber. The vulcanizing agent is one or more of dipentamethylene sulfide, di-t-butyl peroxide, benzoyl peroxide, dicumyl peroxide, and cyclohexanone peroxide; and the lubricant is one or more of stearic acid, polyethylene wax, and oxidized polyethylene wax.

10. Use of the thermally conductive, electrically insulating silicone rubber according to claim 1, characterized in that The heat-conducting insulating silicone rubber is applied to a heat-conducting silicone rubber sheet, a microelectronic device, or a power cable material.

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