Self-repairing silicone rubber composite material and preparation method thereof

Abstract

The invention discloses a self-repairing silicone rubber composite material and a preparation method thereof, and relates to the technical field of silicone rubber materials. The preparation method comprises the following steps: step 1, sequentially carrying out modification treatment on boron nitride by using a silane coupling agent, 4, 4-diaminodiphenyl disulfide and polydimethylsiloxane to obtain modified boron nitride; 2, dispersing the modified boron nitride in a solvent; adding silicone rubber and vulcanized epoxy resin, and uniformly shearing; adding a curing agent while stirring at room temperature; and removing the solvent and curing to obtain the self-repairing silicone rubber composite material. The self-repairing silicone rubber composite material prepared in the invention has excellent mechanical property, self-repairing property and insulating property.

Description

Technical Field

[0001] The present invention relates to the technical field of silicone rubber materials, in particular to a self-repairing silicone rubber composite material and a preparation method thereof. Background Art

[0002] Silicone rubber, a chemically stable insulating material with high and low temperature resistance, is widely used in electrical applications. Due to its inherent mechanical properties, silicone rubber is often reinforced with inorganic materials to effectively improve the mechanical properties of the composite material. However, inorganic reinforcements can cause aggregation and compatibility issues, leading to segregation and poor interfacial interactions in silicone rubber composites.

[0003] On the other hand, during long-term use, silicone rubber composites are prone to local defects such as microcracks due to mechanical damage and localized current flow, which can degrade the mechanical and insulation properties of silicone rubber composites, affecting their reliability and service life in electrical equipment. Therefore, promoting self-healing by introducing dynamic chemical bonds has important application value. However, the self-healing rate of silicone rubber composites is currently limited, and the introduced inorganic reinforcement materials, due to their dispersion and interfacial properties, can hinder the movement of molecular chains, limiting the material's self-healing ability.

[0004] In summary, it is of great significance to solve the above problems and prepare a self-healing silicone rubber composite material. Summary of the Invention

[0005] The object of the present invention is to provide a self-repairing silicone rubber composite material and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing a self-repairing silicone rubber composite material comprises the following steps:

[0008] Step 1: Boron nitride is modified sequentially using a silane coupling agent, 4,4-diaminodiphenyl disulfide, and polydimethylsiloxane to obtain modified boron nitride;

[0009] Step 2: Disperse the modified boron nitride in a solvent; add silicone rubber and vulcanized epoxy resin and shear them evenly; add a curing agent while stirring at room temperature; remove the solvent and cure to obtain a self-healing silicone rubber composite material.

[0010] More optimally, the self-healing silicone rubber composite material includes the following raw materials: by weight, 53 to 62 parts of silicone rubber, 8 to 12 parts of vulcanized epoxy resin, 30 to 35 parts of modified boron nitride, and 2 to 3 parts of curing agent.

[0011] More optimally, the silicone rubber includes RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber in a mass ratio of 8:1:1.

[0012] More optimally, the preparation method of the modified boron nitride is:

[0013] S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in sequence. Under a nitrogen atmosphere, the temperature was set at 75-85°C and stirred for 6-8 hours. The mixture was washed and dried to obtain polydimethylsiloxane.

[0014] S1-2: Add an epoxy siloxy coupling agent to an ethanol-water solution and adjust the pH to 4-6; add hexagonal boron nitride and disperse evenly; ball mill the solution and continue stirring at 60-70° C. for 1-2 hours, centrifuge, and dry to obtain epoxy boron nitride;

[0015] S1-3: Disperse epoxy boron nitride in DMF, add 4,4-diaminodiphenyl disulfide and 2-ethyl-4-methylimidazole; stir at 80-85°C for 4-8 hours under a nitrogen atmosphere, wash, and dry to obtain disulfide boron nitride;

[0016] S1-4: Disperse disulfide boron nitride in tetrahydrofuran, add p-phenylene diisocyanate and polydimethylsiloxane; stir at room temperature under nitrogen atmosphere for 4 to 5 hours, wash, and dry to obtain modified boron nitride.

[0017] More optimally, in the polydimethylsiloxane, the molar ratio of 4-allylcatechol, paraformaldehyde, and aminopropyl diblocked polydimethylsiloxane is 0.1:0.2 to 0.4:0.1; and the average molecular weight of the aminopropyl diblocked polydimethylsiloxane is 1000.

[0018] More optimally, in the raw materials of the epoxy boron nitride, the mass ratio of the epoxy silicone coupling agent and the hexagonal boron nitride is 1:0.1-0.15; in the raw materials of the disulfide-based boron nitride, the mass ratio of the epoxy boron nitride and 4,4-diaminodiphenyl disulfide is 1:0.12-0.15; in the raw materials of the modified boron nitride, the mass ratio of the disulfide-based boron nitride, p-phenylene diisocyanate, and polydimethylsiloxane is 1:0.1-0.12:0.5-0.6.

[0019] More optimally, the curing agent includes a peroxide initiator, organic tin and aminopropyl dicapped polydimethylsiloxane in a mass ratio of 0.8:0.2:1-2.

[0020] More optimally, in step 2, the solvent is tetrahydrofuran; and the curing conditions are: curing at room temperature for 10 to 12 hours, and then curing at 120 to 150° C. for 0.5 to 1 hour.

[0021] More optimally, the preparation method of the vulcanized epoxy resin is: heating and activating bisphenol A diglycidyl ether, adding 4,4-diaminodiphenyl disulfide and dipropylene terephthalate, and stirring at 80-85° C. for 1-2 hours to obtain the vulcanized epoxy resin.

[0022] A self-repairing silicone rubber composite material is prepared by a method for preparing the self-repairing silicone rubber composite material.

[0023] Compared with existing technologies, the present invention achieves the following beneficial effects: based on compounded silicone rubber, the introduction of vulcanized epoxy resin as an organic reinforcement and boron nitride as an inorganic reinforcement improves both mechanical properties and insulation. Furthermore, the use of vulcanized epoxy resin and the modification of boron nitride enhance interfacial interactions and synergistically produce self-healing properties.

[0024] In this solution, silicone rubber is compounded in a specific ratio of 8:1:1: RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber. The RTV silicone rubber, as the primary material, provides room temperature vulcanization performance and basic elasticity. The VMQ silicone rubber and isocyanate-terminated silicone rubber promote crosslinking and enhance interfacial properties with vulcanized epoxy resins and modified boron nitride, effectively ensuring mechanical properties and insulation. Furthermore, the isocyanate-terminated silicone rubber forms reversible aminoester bonds with the epoxy resin, while the VMQ silicone rubber forms a crosslinked network with the sulfide, promoting the construction of a dynamic repair network and enhancing self-healing properties.

[0025] In this scheme, the introduction of epoxy vulcanized resin can effectively improve mechanical properties and self-healing properties. Epoxy resin has rigid molecular chains, and when compounded with flexible silicone rubber, it can form an interpenetrating network structure, effectively improving mechanical properties such as tensile strength. It also has certain insulating properties, effectively improving the reliability of electrical applications. Furthermore, epoxy vulcanized resin, after being modified with 4,4-diaminodiphenyl disulfide, possesses dynamic disulfide bonds, and its break-and-recombination properties give the material self-healing capabilities. At the same time, the cross-linking effect of epoxy vulcanized resin can reduce the migration of polar groups in the silicone rubber molecular chain, preventing the degradation of dielectric properties in humid environments. However, it should be noted that the amount of epoxy vulcanized resin introduced should not be too large, as excessive amounts will cause phase separation, which is detrimental to overall performance.

[0026] The proposed solution incorporates boron nitride as an inorganic filler, enhancing both the insulation and thermal conductivity network. However, boron nitride suffers from dispersibility and compatibility issues, which impact its mechanical and self-healing properties. Therefore, a series of modifications were performed to improve its dispersion and interfacial interactions, while also enhancing the self-healing properties of the silicone rubber composite.

[0027] Compared to the conventional method of modifying fillers solely with silane coupling agents, boron nitride is more difficult to disperse than granular fillers due to its flake-like form. Therefore, this method first uses epoxy-silane coupling for modification, then grafts or intercalates 4,4-diaminodiphenyl disulfide through the reaction between amino groups and epoxy groups. Finally, the modified boron nitride is further compounded with polydimethylsiloxane through the reaction between p-phenylenediisocyanate and amino groups. The inclusion of 4,4-diaminodiphenyl disulfide in this material effectively improves its compatibility with epoxy vulcanized resins, while the inclusion of polydimethylsiloxane improves its compatibility with silicone rubber. Furthermore, the hydroxyl and amino groups on the modified boron nitride can crosslink with silicone rubber and epoxy vulcanized resins, effectively enhancing interfacial interactions and ensuring mechanical properties.

[0028] Among them, the modification of diaminodiphenyl disulfide provides a dynamic disulfide bond; and polydimethylsiloxane is prepared from 4-allylcatechol, polyformaldehyde, and aminopropyl double-terminated polydimethylsiloxane to form a benzoxazine structure; and after it is compounded with disulfide-based boron nitride using p-phenylene diisothiocyanate, it contains a thiourea bond; the steric hindrance of benzoxazine and the activity of thiourea can also break and recombine, so after modifying boron nitride, not only the interface compatibility is improved, but also the self-healing performance is improved. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] It should be noted that the following parts are calculated by weight, and the purchase manufacturers of all raw materials involved in the present invention are not subject to any special restrictions. Examples include: In the following examples, the model of RTV silicone rubber is The vinyl content of E43 and VMQ silicone rubber is 0.1-0.3%, and the model is 3003, the model of isocyanate terminated silicone rubber is IA-45 and aminopropyl di-terminated polydimethylsiloxane are of model XAS-1001 and average molecular weight 1000; the CAS number of p-phenylenediisocyanate is 4044-65-9, and the CAS number of 4-allylcatechol is 1126-61-0; the particle size of hexagonal boron nitride is 12500 mesh, and the brand is BSL-BN-1; all relevant raw materials are commercially available.

[0031] The preparation method of the vulcanized epoxy resin is as follows: 40 parts of bisphenol A diglycidyl ether are heated to 70° C., 2 parts of 4,4-diaminodiphenyl disulfide and 3 parts of dipropylene terephthalate are added, and the mixture is stirred at 80° C. for 1 hour to obtain the vulcanized epoxy resin.

[0032] Example 1: A method for preparing a self-repairing silicone rubber composite material, comprising the following steps:

[0033] Step 1: Preparation of modified boron nitride:

[0034] S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in a molar ratio of 0.1:0.32:0.1 in sequence. Under a nitrogen atmosphere, the mixture was stirred at 80°C for 8 hours, washed, and dried to obtain polydimethylsiloxane.

[0035] S1-2: Add epoxy siloxy coupling agent KH560 to an 80 wt% ethanol-water solution and adjust the pH to 4.6; add hexagonal boron nitride and disperse evenly; ball mill at 1000 rpm for 2 hours, continue stirring at 60°C for 1 hour, centrifuge, and dry to obtain epoxy boron nitride; wherein the mass ratio of epoxy siloxy coupling agent KH560 to hexagonal boron nitride is 1:0.12;

[0036] S1-3: Dispersing epoxy boron nitride in DMF, adding 4,4-diaminodiphenyl disulfide and 2-ethyl-4-methylimidazole; stirring at 80°C under a nitrogen atmosphere for 6 hours, washing, and drying to obtain disulfide boron nitride; wherein the mass ratio of epoxy boron nitride to 4,4-diaminodiphenyl disulfide is 1:0.15, and the amount of 2-ethyl-4-methylimidazole added is 1 wt% of 4,4-diaminodiphenyl disulfide;

[0037] S1-4: Dispersing disulfide-based boron nitride in tetrahydrofuran, adding p-phenylene diisocyanate and polydimethylsiloxane; stirring at room temperature under a nitrogen atmosphere for 5 hours, washing, and drying to obtain modified boron nitride; wherein the mass ratio of disulfide-based boron nitride, p-phenylene diisocyanate, and polydimethylsiloxane is 1:0.1:0.5;

[0038] Step 2: Disperse 32 parts of modified boron nitride in 100 parts of tetrahydrofuran; add 58 parts of silicone rubber (composed of RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber in a ratio of 8:1:1) and 10 parts of vulcanized epoxy resin and shear them evenly; add 3 parts of curing agent (composed of benzoyl peroxide, dibutyltin dilaurate, and aminopropyl di-terminated polydimethylsiloxane in a ratio of 0.8:0.2:2) while stirring at room temperature; remove tetrahydrofuran at 40°C, cure at room temperature for 12 hours, and then cure at 135°C for 1 hour to obtain a self-healing silicone rubber composite material.

[0039] Example 2: A method for preparing a self-repairing silicone rubber composite material, comprising the following steps:

[0040] Step 1: Preparation of modified boron nitride:

[0041] S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in a molar ratio of 0.1:0.32:0.1 in sequence. Under a nitrogen atmosphere, the mixture was stirred at 80°C for 8 hours, washed, and dried to obtain polydimethylsiloxane.

[0042] S1-2: Add epoxy siloxy coupling agent KH560 to an 80 wt% ethanol-water solution and adjust the pH to 4.6; add hexagonal boron nitride and disperse evenly; ball mill at 1000 rpm for 2 hours, continue stirring at 60°C for 1 hour, centrifuge, and dry to obtain epoxy boron nitride; wherein the mass ratio of epoxy siloxy coupling agent KH560 to hexagonal boron nitride is 1:0.12;

[0043] S1-3: Dispersing epoxy boron nitride in DMF, adding 4,4-diaminodiphenyl disulfide and 2-ethyl-4-methylimidazole; stirring at 80°C under a nitrogen atmosphere for 6 hours, washing, and drying to obtain disulfide boron nitride; wherein the mass ratio of epoxy boron nitride to 4,4-diaminodiphenyl disulfide is 1:0.15, and the amount of 2-ethyl-4-methylimidazole added is 1 wt% of 4,4-diaminodiphenyl disulfide;

[0044] S1-4: Dispersing disulfide-based boron nitride in tetrahydrofuran, adding p-phenylene diisocyanate and polydimethylsiloxane; stirring at room temperature under a nitrogen atmosphere for 5 hours, washing, and drying to obtain modified boron nitride; wherein the mass ratio of disulfide-based boron nitride, p-phenylene diisocyanate, and polydimethylsiloxane is 1:0.1:0.5;

[0045] Step 2: Disperse 35 parts of modified boron nitride in 100 parts of tetrahydrofuran; add 53 parts of silicone rubber (composed of RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber in a ratio of 8:1:1) and 12 parts of vulcanized epoxy resin and shear them evenly; add 3 parts of curing agent (composed of benzoyl peroxide, dibutyltin dilaurate, and aminopropyl di-terminated polydimethylsiloxane in a ratio of 0.8:0.2:2) while stirring at room temperature; remove tetrahydrofuran at 40°C, cure at room temperature for 12 hours, and then cure at 135°C for 1 hour to obtain a self-healing silicone rubber composite material.

[0046] Example 3: A method for preparing a self-repairing silicone rubber composite material, comprising the following steps:

[0047] Step 1: Preparation of modified boron nitride:

[0048] S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in a molar ratio of 0.1:0.32:0.1 in sequence. Under a nitrogen atmosphere, the mixture was stirred at 80°C for 8 hours, washed, and dried to obtain polydimethylsiloxane.

[0049] S1-2: Add epoxy siloxy coupling agent KH560 to an 80 wt% ethanol-water solution and adjust the pH to 4.6; add hexagonal boron nitride and disperse evenly; ball mill at 1000 rpm for 2 hours, continue stirring at 60°C for 1 hour, centrifuge, and dry to obtain epoxy boron nitride; wherein the mass ratio of epoxy siloxy coupling agent KH560 to hexagonal boron nitride is 1:0.12;

[0050] S1-3: Dispersing epoxy boron nitride in DMF, adding 4,4-diaminodiphenyl disulfide and 2-ethyl-4-methylimidazole; stirring at 80°C under a nitrogen atmosphere for 6 hours, washing, and drying to obtain disulfide boron nitride; wherein the mass ratio of epoxy boron nitride to 4,4-diaminodiphenyl disulfide is 1:0.15, and the amount of 2-ethyl-4-methylimidazole added is 1 wt% of 4,4-diaminodiphenyl disulfide;

[0051] S1-4: Dispersing disulfide-based boron nitride in tetrahydrofuran, adding p-phenylene diisocyanate and polydimethylsiloxane; stirring at room temperature under a nitrogen atmosphere for 5 hours, washing, and drying to obtain modified boron nitride; wherein the mass ratio of disulfide-based boron nitride, p-phenylene diisocyanate, and polydimethylsiloxane is 1:0.1:0.5;

[0052] Step 2: Disperse 30 parts of modified boron nitride in 100 parts of tetrahydrofuran; add 62 parts of silicone rubber (composed of RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber in a ratio of 8:1:1) and 8 parts of vulcanized epoxy resin and shear them evenly; add 2 parts of curing agent (composed of benzoyl peroxide, dibutyltin dilaurate, and aminopropyl di-terminated polydimethylsiloxane in a ratio of 0.8:0.2:1) while stirring at room temperature; remove tetrahydrofuran at 40°C, cure at room temperature for 12 hours, and then cure at 135°C for 1 hour to obtain a self-healing silicone rubber composite material.

[0053] Comparative Example 1: Only RTV silicone rubber was used; the rest was the same as in Example 1; the details are as follows:

[0054] Step 1: Preparation of modified boron nitride:

[0055] S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in a molar ratio of 0.1:0.32:0.1 in sequence. Under a nitrogen atmosphere, the mixture was stirred at 80°C for 8 hours, washed, and dried to obtain polydimethylsiloxane.

[0056] S1-2: Add epoxy siloxy coupling agent KH560 to an 80 wt% ethanol-water solution and adjust the pH to 4.6; add hexagonal boron nitride and disperse evenly; ball mill at 1000 rpm for 2 hours, continue stirring at 60°C for 1 hour, centrifuge, and dry to obtain epoxy boron nitride; wherein the mass ratio of epoxy siloxy coupling agent KH560 to hexagonal boron nitride is 1:0.12;

[0057] S1-3: Dispersing epoxy boron nitride in DMF, adding 4,4-diaminodiphenyl disulfide and 2-ethyl-4-methylimidazole; stirring at 80°C under a nitrogen atmosphere for 6 hours, washing, and drying to obtain disulfide boron nitride; wherein the mass ratio of epoxy boron nitride to 4,4-diaminodiphenyl disulfide is 1:0.15, and the amount of 2-ethyl-4-methylimidazole added is 1 wt% of 4,4-diaminodiphenyl disulfide;

[0058] S1-4: Dispersing disulfide-based boron nitride in tetrahydrofuran, adding p-phenylene diisocyanate and polydimethylsiloxane; stirring at room temperature under a nitrogen atmosphere for 5 hours, washing, and drying to obtain modified boron nitride; wherein the mass ratio of disulfide-based boron nitride, p-phenylene diisocyanate, and polydimethylsiloxane is 1:0.1:0.5;

[0059] Step 2: Disperse 32 parts of modified boron nitride in 100 parts of tetrahydrofuran; add 58 parts of RTV silicone rubber and 10 parts of vulcanized epoxy resin and shear them evenly; add 3 parts of curing agent (composed of benzoyl peroxide, dibutyltin dilaurate and aminopropyl dicapped polydimethylsiloxane in a ratio of 0.8:0.2:2) under stirring at room temperature; remove tetrahydrofuran at 40°C, cure at room temperature for 12 hours, and then cure at 135°C for 1 hour to obtain a self-healing silicone rubber composite material.

[0060] Comparative Example 2: Only silane coupling agent was used to modify boron nitride; the rest was the same as Example 1; the details are as follows:

[0061] Step 1: adding epoxy siloxane coupling agent KH560 to an 80 wt% ethanol-water solution and adjusting the pH to 4.6; adding hexagonal boron nitride and dispersing the mixture uniformly; ball milling the mixture at 1000 rpm for 2 hours, stirring the mixture at 60° C. for 1 hour, centrifuging the mixture, and drying the mixture to obtain epoxy boron nitride; wherein the mass ratio of epoxy siloxane coupling agent KH560 to hexagonal boron nitride is 1:0.12;

[0062] Step 2: Disperse 32 parts of epoxy boron nitride in 100 parts of tetrahydrofuran; add 58 parts of silicone rubber (composed of RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber in a ratio of 8:1:1) and 10 parts of vulcanized epoxy resin and shear them evenly; add 3 parts of curing agent (composed of benzoyl peroxide, dibutyltin dilaurate, and aminopropyl di-terminated polydimethylsiloxane in a ratio of 0.8:0.2:2) under stirring at room temperature; remove tetrahydrofuran at 40°C, cure at room temperature for 12 hours, and then cure at 135°C for 1 hour to obtain a self-healing silicone rubber composite material.

[0063] Comparative Example 3: Boron nitride was not modified with 4,4-diaminodiphenyl disulfide; the rest was the same as Example 1; the details are as follows:

[0064] Step 1: Preparation of modified boron nitride:

[0065] S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in a molar ratio of 0.1:0.32:0.1 in sequence. Under a nitrogen atmosphere, the mixture was stirred at 80°C for 8 hours, washed, and dried to obtain polydimethylsiloxane.

[0066] S1-2: Add epoxy siloxy coupling agent KH560 to an 80 wt% ethanol-water solution and adjust the pH to 4.6; add hexagonal boron nitride and disperse evenly; ball mill at 1000 rpm for 2 hours, continue stirring at 60°C for 1 hour, centrifuge, and dry to obtain epoxy boron nitride; wherein the mass ratio of epoxy siloxy coupling agent KH560 to hexagonal boron nitride is 1:0.12;

[0067] S1-3: Dispersing epoxy boron nitride in DMF, adding polydimethylsiloxane and 2-ethyl-4-methylimidazole; stirring at 80°C under a nitrogen atmosphere for 6 hours, washing, and drying to obtain disulfide boron nitride; wherein the mass ratio of epoxy boron nitride to polydimethylsiloxane is 1:0.5, and the amount of 2-ethyl-4-methylimidazole added is 1 wt% of the polydimethylsiloxane;

[0068] Step 2: Disperse 32 parts of modified boron nitride in 100 parts of tetrahydrofuran; add 58 parts of silicone rubber (composed of RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber in a ratio of 8:1:1) and 10 parts of vulcanized epoxy resin and shear them evenly; add 3 parts of curing agent (composed of benzoyl peroxide, dibutyltin dilaurate, and aminopropyl di-terminated polydimethylsiloxane in a ratio of 0.8:0.2:2) while stirring at room temperature; remove tetrahydrofuran at 40°C, cure at room temperature for 12 hours, and then cure at 135°C for 1 hour to obtain a self-healing silicone rubber composite material.

[0069] Comparative Example 4: The amount of vulcanized epoxy resin introduced was increased; the rest was the same as Example 1; the details are as follows:

[0070] Step 1: Preparation of modified boron nitride:

[0071] S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in a molar ratio of 0.1:0.32:0.1 in sequence. Under a nitrogen atmosphere, the mixture was stirred at 80°C for 8 hours, washed, and dried to obtain polydimethylsiloxane.

[0072] S1-2: Add epoxy siloxy coupling agent KH560 to an 80 wt% ethanol-water solution and adjust the pH to 4.6; add hexagonal boron nitride and disperse evenly; ball mill at 1000 rpm for 2 hours, continue stirring at 60°C for 1 hour, centrifuge, and dry to obtain epoxy boron nitride; wherein the mass ratio of epoxy siloxy coupling agent KH560 to hexagonal boron nitride is 1:0.12;

[0073] S1-3: Dispersing epoxy boron nitride in DMF, adding 4,4-diaminodiphenyl disulfide and 2-ethyl-4-methylimidazole; stirring at 80°C under a nitrogen atmosphere for 6 hours, washing, and drying to obtain disulfide boron nitride; wherein the mass ratio of epoxy boron nitride to 4,4-diaminodiphenyl disulfide is 1:0.15, and the amount of 2-ethyl-4-methylimidazole added is 1 wt% of 4,4-diaminodiphenyl disulfide;

[0074] S1-4: Dispersing disulfide-based boron nitride in tetrahydrofuran, adding p-phenylene diisocyanate and polydimethylsiloxane; stirring at room temperature under a nitrogen atmosphere for 5 hours, washing, and drying to obtain modified boron nitride; wherein the mass ratio of disulfide-based boron nitride, p-phenylene diisocyanate, and polydimethylsiloxane is 1:0.1:0.5;

[0075] Step 2: Disperse 32 parts of modified boron nitride in 100 parts of tetrahydrofuran; add 50 parts of silicone rubber (composed of RTV silicone rubber, VMQ silicone rubber, and isocyanate-terminated silicone rubber in a ratio of 8:1:1) and 18 parts of vulcanized epoxy resin and shear them evenly; add 3 parts of curing agent (composed of benzoyl peroxide, dibutyltin dilaurate, and aminopropyl di-terminated polydimethylsiloxane in a ratio of 0.8:0.2:2) while stirring at room temperature; remove tetrahydrofuran at 40°C, cure at room temperature for 12 hours, and then cure at 135°C for 1 hour to obtain a self-healing silicone rubber composite material.

[0076] Performance test: The self-healing silicone rubber composite materials prepared in Example 1 and Comparative Examples 1 to 4 were subjected to relevant performance tests; (1) the tensile strength was tested at a tensile rate of 500 mm / min using a universal material tester, wherein the spline was prepared into a dumbbell shape with reference to the standard of GB / T528-2009; (2) a scratch recovery test was performed, with the sample having a thickness of 1 mm, a scratch length of 5 mm, and a depth of 50 μm, and self-healing was performed at 90°C for 24 hours; and a high-voltage DC breakdown test was performed on the front and back samples using a 5 mm ball-ball electrode, and the electrical damage self-healing rate was calculated by comparing the breakdown strength before and after; the obtained data are shown in the following table:

[0077] sample Tensile strength MPa Self-healing rate of electrical damage % Example 1 4.32 74.3 Example 2 4.16 73.1 Example 3 4.21 73.6 Comparative Example 1 3.93 66.3 Comparative Example 2 3.63 48.7 Comparative Example 3 3.82 62.3 Comparative Example 4 3.98 69.2

[0078] Conclusion: The data in the table above indicate that the present application has produced a self-healing silicone rubber composite material with excellent mechanical properties and self-healing rate. Furthermore, a comparison of the data from Comparative Examples 1 to 4 indicates that in Comparative Example 1, the use of only RTV silicone rubber resulted in reduced crosslinking and the failure to form aminoester bonds in the isocyanate-terminated silicone rubber, leading to decreased mechanical properties and self-healing properties. In Comparative Example 2, the use of only a silane coupling agent to modify boron nitride resulted in decreased dispersibility, reduced interfacial crosslinking, and decreased self-healing properties. In Comparative Example 3, the absence of 4,4′-diaminodiphenyl disulfide in the modified boron nitride resulted in a slight decrease in performance. In Comparative Example 4, the addition of vulcanized epoxy resin resulted in interfacial phase delamination, which reduced related performance.

[0079] 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 aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a self-repairing silicone rubber composite material, characterized in that: The following steps are involved: Step 1: Boron nitride is modified sequentially using a silane coupling agent, 4,4-diaminodiphenyl disulfide, and polydimethylsiloxane to obtain modified boron nitride; Step 2: Disperse the modified boron nitride in a solvent; add silicone rubber and vulcanized epoxy resin and shear them evenly; add a curing agent while stirring at room temperature; remove the solvent and cure to obtain a self-healing silicone rubber composite material.

2. The method for preparing a self-repairing silicone rubber composite material according to claim 1, wherein: The self-repairing silicone rubber composite material comprises the following raw materials: by weight, 53 to 62 parts of silicone rubber, 8 to 12 parts of vulcanized epoxy resin, 30 to 35 parts of modified boron nitride, and 2 to 3 parts of curing agent.

3. The method for preparing a self-repairing silicone rubber composite material according to claim 1, wherein: The silicone rubber includes RTV silicone rubber, VMQ silicone rubber and isocyanate-terminated silicone rubber in a mass ratio of 8:1:

1.

4. The method for preparing a self-repairing silicone rubber composite material according to claim 1, wherein: The preparation method of the modified boron nitride is: S1-1: 4-allylcatechol, paraformaldehyde, and aminopropyl dicapped polydimethylsiloxane were added to chloroform in sequence. Under a nitrogen atmosphere, the temperature was set at 75-85°C and stirred for 6-8 hours. The mixture was washed and dried to obtain polydimethylsiloxane. S1-2: Add an epoxy siloxy coupling agent to an ethanol-water solution and adjust the pH to 4-6; add hexagonal boron nitride and disperse evenly; ball mill the solution and continue stirring at 60-70° C. for 1-2 hours, centrifuge, and dry to obtain epoxy boron nitride; S1-3: Disperse epoxy boron nitride in DMF, add 4,4-diaminodiphenyl disulfide and 2-ethyl-4-methylimidazole; Under a nitrogen atmosphere, stirring at 80-85° C. for 4-8 hours, washing, and drying to obtain disulfide boron nitride; S1-4: Disperse disulfide boron nitride in tetrahydrofuran, add p-phenylene diisocyanate and polydimethylsiloxane; stir at room temperature under nitrogen atmosphere for 4 to 5 hours, wash, and dry to obtain modified boron nitride.

5. The method for preparing a self-repairing silicone rubber composite material according to claim 1, wherein: In the polydimethylsiloxane, the molar ratio of 4-allylcatechol, paraformaldehyde and aminopropyl diblocked polydimethylsiloxane is 0.1:0.2 to 0.4:0.1; and the average molecular weight of the aminopropyl diblocked polydimethylsiloxane is 1000.

6. The method for preparing a self-repairing silicone rubber composite material according to claim 1, characterized in that: Among the raw materials of the epoxy boron nitride, the mass ratio of the epoxy silicone coupling agent to the hexagonal boron nitride is 1:0.1-0.15; among the raw materials of the disulfide-based boron nitride, the mass ratio of the epoxy boron nitride to 4,4-diaminodiphenyl disulfide is 1:0.12-0.15; and among the raw materials of the modified boron nitride, the mass ratio of the disulfide-based boron nitride, p-phenylene diisocyanate, and polydimethylsiloxane is 1:0.1-0.12:0.5-0.

6.

7. The method for preparing a self-repairing silicone rubber composite material according to claim 1, wherein: The curing agent comprises a peroxide initiator, organic tin and aminopropyl double-terminated polydimethylsiloxane in a mass ratio of 0.8:0.2:1-2.

8. The method for preparing a self-repairing silicone rubber composite material according to claim 1, characterized in that: In step 2, the solvent is tetrahydrofuran; and the curing conditions are: curing at room temperature for 10 to 12 hours, and then curing at 120 to 150° C. for 0.5 to 1 hour.

9. The method for preparing a self-repairing silicone rubber composite material according to claim 1, wherein: The preparation method of the vulcanized epoxy resin comprises the following steps: heating and activating bisphenol A diglycidyl ether, adding 4,4-diaminodiphenyl disulfide and dipropylene terephthalate, and stirring at 80-85° C. for 1-2 hours to obtain the vulcanized epoxy resin. 10 . The self-repairing silicone rubber composite material prepared according to the method for preparing a self-repairing silicone rubber composite material according to any one of claims 1 to 9.