Self-healing insulating composite material and method for manufacturing same

Abstract

The application discloses a kind of self-repairing insulation composite material and preparation method thereof, it is related to insulating material technical field.A kind of self-repairing insulation composite material, its structure includes by inside and outside sequentially arranged self-repairing core system, insulating core and dielectric shell;Insulating core is hollow silica microsphere, self-repairing core system includes polyethylene glycol modified epoxy resin and dicyandiamide, and dielectric shell is composed of polyaniline nanoparticles.Its preparation method includes steps: polyethylene glycol modified epoxy resin preparation, silica microsphere preparation and polyaniline deposition.It can improve the insulation performance of material while ensuring the lightweight of material, and also can play the role of self-repairing, provides a breakthrough insulating material solution for new energy automobile motor, high-voltage direct-current cable and other application scenarios, promotes electronic and electrical equipment to more efficient, more reliable direction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of insulating materials, in particular to a self-repairing insulating composite material and a preparation method thereof. BACKGROUND

[0002] With the development of electronic and electrical equipment towards miniaturization, high power density and high temperature environment application, the performance requirements of the corresponding insulating materials are becoming more and more stringent. Traditional polymers (such as epoxy resin, polyimide, silicone rubber, etc.) need to be broken through in the core indicators of higher insulating strength and lightweight.

[0003] However, in the existing material system, in order to reduce the density of the material, a porous structure or a low-density filler needs to be introduced, but the increase of porosity easily leads to local electric field distortion, thereby reducing the insulating strength, and there is a problem of inversion of the relationship between material lightweight and insulating performance.

[0004] In addition, the intrinsic breakdown field strength of traditional polymers is limited, and if the performance is to be improved, the coating thickness needs to be increased, which is contrary to the development trend of equipment miniaturization; at the same time, due to the particularity of the application scene (hot and humid scene), the existing materials are prone to corrosion damage and other situations during use, which adversely affects the insulating performance of the materials, and therefore the materials need to be regularly inspected and maintained, and the damaged parts need to be replaced and repaired, which is time-consuming and laborious. SUMMARY

[0005] The purpose of the present application is to provide a self-repairing insulating composite material and a preparation method thereof, which can improve the insulating performance of the material while ensuring the lightweight of the material, and also has the function of self-repairing, providing a breakthrough insulating material solution for application scenarios such as new energy automobile motors and high-voltage DC cables, and promoting the development of electronic and electrical equipment towards higher efficiency and reliability.

[0006] The technical solution of the present application is as follows:

[0007] On the one hand, the present application provides a self-repairing insulating composite material, the structure of which comprises a self-repairing core system, an insulating core and a dielectric shell arranged from inside to outside in sequence.

[0008] The insulating core is a hollow silica microsphere, the self-repairing core system comprises polyethylene glycol modified epoxy resin and dicyandiamide, and the dielectric shell is composed of polyaniline nanoparticles.

[0009] The self-repairing core system is encapsulated in the internal cavity of the hollow silica microsphere, and the polyaniline nanoparticles are deposited on the surface of the hollow silica microsphere to form the dielectric shell.

[0010] Further, in some embodiments of the present application, the insulating core has a particle size of 70-90 nm and a wall thickness of 15-25 nm, and the wall layer is composed of silica particles with a particle size of 5-10 nm.

[0011] Further, in some embodiments of the present application, the dielectric shell is composed of polyaniline nanoparticles with a particle size of 1-3 nm, and the distribution area of the polyaniline nanoparticles accounts for 20-25% of the surface area of the hollow silica microspheres.

[0012] On the other hand, the embodiments of the present application also provide a preparation method of the self-repairing insulating composite material, which comprises the following steps:

[0013] S1 Preparation of polyethylene glycol modified epoxy resin: taking epoxy resin and polyethylene glycol, and reacting under the action of a catalyst to prepare polyethylene glycol modified epoxy resin;

[0014] S2 Preparation of silica microspheres: taking the prepared polyethylene glycol modified epoxy resin and finely divided dicyandiamide, and dissolving them in toluene as an oil phase; taking a solution containing hydrochloric acid and sodium dodecyl sulfate as an aqueous phase; forming an O / W emulsion system by high-speed shearing emulsification, and adding tetraethyl orthosilicate dropwise into the O / W emulsion system to react, so that the tetraethyl orthosilicate is hydrolyzed and condensed to form a silica shell layer at the oil-water interface; centrifuging and washing the obtained product with ethanol, and drying to obtain silica microspheres encapsulating polyethylene glycol modified epoxy resin;

[0015] S3 Polyaniline deposition: taking the prepared silica microspheres, adding an aqueous hydrochloric acid solution, and dispersing by ultrasonic; adding aniline and stirring to obtain a mixture; taking ammonium persulfate and dissolving it in an aqueous hydrochloric acid solution by ultrasonic to obtain an ammonium persulfate-aqueous hydrochloric acid solution; adding the ammonium persulfate-aqueous hydrochloric acid solution dropwise into the mixture to react, obtaining a reaction product, and filtering, washing, and drying to obtain a finished product.

[0016] Further, in some embodiments of the present application, in the preparation step of the polyethylene glycol modified epoxy resin, the molar ratio of the used epoxy resin and polyethylene glycol is 1:0.8-1:1.5, and the catalyst used is triphenylphosphine, and the catalyst dosage is 0.1% of the total mass of the epoxy resin and polyethylene glycol.

[0017] Further, in some embodiments of the present application, in the preparation step of the silica microspheres, fumed silica is additionally added during the process of forming the O / W emulsion system by high-speed shearing emulsification to prevent sedimentation.

[0018] Further, in some embodiments of the present application, in the above-mentioned step of preparing silica microspheres, the prepared polyethylene glycol modified epoxy resin and 5-10 wt% micronized dicyandiamide are co-dissolved in toluene as an oil phase; a solution containing 0.1 M hydrochloric acid and 0.5 wt% sodium dodecyl sulfonate is used as an aqueous phase, and 1 wt% fumed silica is further added, and an O / W emulsion system is formed by high-speed shearing emulsification.

[0019] Further, in some embodiments of the present application, in the above-mentioned step of preparing silica microspheres, the diameter of the emulsion droplets in the formed O / W emulsion system is 200-500 nm.

[0020] Further, in some embodiments of the present application, in the above-mentioned step of preparing silica microspheres, tetraethyl orthosilicate is added dropwise into the O / W emulsion system at room temperature for reaction.

[0021] Further, in some embodiments of the present application, in the above-mentioned step of depositing polyaniline, the ammonium persulfate-hydrochloric acid aqueous solution is added dropwise into the mixture under ice bath conditions for reaction.

[0022] Further, in some embodiments of the present application, in the above-mentioned step of depositing polyaniline, the weight ratio of aniline to silica microspheres satisfies 0.15-0.25:1.

[0023] Compared with the prior art, the embodiments of the present application have at least the following advantages or beneficial effects:

[0024] In view of the above, the embodiments of the present application provide a self-repairing insulation composite material and a preparation method thereof, which construct a ternary synergistic structure of "self-repairing core-insulation nucleus-dielectric shell", and realize the synergistic promotion of lightweight, high insulation, toughness and self-repairing property. Specifically, hollow silica microspheres (HSMS) are used as the insulation nucleus, polyaniline nanoparticles (PANI) are deposited on the surface thereof, and a polyethylene glycol (PEG) modified epoxy resin and a dicyandiamide curing agent self-repairing system are encapsulated in the interior thereof.

[0025] The hollow silica microspheres effectively inhibit the generation of leakage current and meet the lightweight demand due to their excellent insulation performance and low density characteristics; the resistivity of the surface polyaniline nanoparticles can be accurately controlled in the range of 10 6 -10¹ 0 Ω·cm, and as efficient charge traps, significantly delay the migration of carriers; the PEG modified epoxy resin acts as a soft template and a self-repairing component, the PEG segment thereof can guide the directional growth of the silica shell layer and also act as a plasticizing medium to trigger the release of the curing agent at low temperature, and can autonomously repair microcracks when mechanical damage occurs, thereby realizing the self-repairing function, the self-repairing mechanism is easy to trigger, and the practicability of the material can be greatly improved.

[0026] In addition, the hollow silica insulating core and the nanoscale polyaniline dielectric shell jointly build a "charge trap-insulating barrier" synergistic network, which greatly improves the breakdown field strength by absorbing local charges and dispersing electric field intensity, and only a small amount of addition is needed in the composite material to significantly improve the insulation performance, thereby greatly reducing the density of the composite material. The PEG segment acts as a plasticizer to significantly improve the overall elongation at break of the material; the flexible long molecular chain of PEG forms a "molecular pulley" effect with SiO2, PANI and the like, so that the composite material maintains excellent flexibility in a wide temperature range of -40℃ to 120℃; the PEG segment can enhance the interfacial compatibility, so that the performance retention rate of the composite material after damp-heat aging at 85℃ / 85% RH is still greater than 95%.

[0027] In summary, the application creatively builds a self-repairing system composed of PEG modified epoxy resin and dicyandiamide as encapsulating material, constructs hollow silica insulating core on its surface, and then deposits polyaniline on the surface; realizes the synergistic optimization of "self-repairing-electric field regulation-interface stability", and provides a breakthrough solution for insulating materials for new energy automobile motor, high-voltage DC cable and other application scenarios, and promotes the development of electronic and electrical equipment to be more efficient and more reliable. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0029] It should be noted that the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or equipment. Without more limitations, the elements defined by the statement "comprising" do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0030] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0031] The features and properties of the application will be further described below in combination with the embodiments.

[0032] Embodiment 1

[0033] The self-repairing insulation composite provided by the embodiment of the present application comprises, from inside to outside, a self-repairing core system, an insulation core, and a dielectric shell; the insulation core is a hollow silica microsphere; the self-repairing core system comprises polyethylene glycol modified epoxy resin and dicyandiamide; and the dielectric shell is composed of polyaniline nanoparticles.

[0034] The hollow cavity in the hollow silica microsphere is encapsulated with the self-repairing core system; the surface of the hollow silica microsphere is deposited with the polyaniline nanoparticles to form the dielectric shell. The insulation core has a particle size of 70-90 nm and a wall thickness of 15-25 nm, and the wall layer is composed of silica particles with a particle size of 5-10 nm. The dielectric shell is composed of polyaniline nanoparticles with a particle size of 1-3 nm, and the distribution area of the polyaniline nanoparticles accounts for 20-25% of the surface area of the hollow silica microsphere.

[0035] The self-repairing insulation composite is prepared by the following method:

[0036] S1. Preparation of polyethylene glycol modified epoxy resin: epoxy resin (E-51) and polyethylene glycol (PEG) are taken in a molar ratio of 1:1, and under the action of a catalyst (0.1 wt% triphenylphosphine), the mixture is reacted at 80°C for 6 h to prepare polyethylene glycol modified epoxy resin;

[0037] S2. Preparation of silica microspheres: oil phase preparation: 30 g of polyethylene glycol modified epoxy resin and 2.5 g of micronized dicyandiamide are weighed into a beaker, and 100 mL of toluene is added. Stir in a 50-60°C water bath until completely dissolved and clear. Water phase preparation: in another beaker, 0.5 g of sodium dodecyl sulfate (SDS) is dissolved in 90 mL of deionized water, and then 10 mL of 0.1M hydrochloric acid solution is added, and stirred uniformly. Finally, 1 g of fumed silica is added, and a high-speed shearing emulsifier (such as 10000 rpm, 2 minutes) is used for pre-dispersion.

[0038] Continue high-speed shearing emulsification at a speed of 10000 rpm for 10 min to form an O / W emulsion system (droplets 200-500 nm), and add 40 mL of tetraethyl orthosilicate (TEOS) dropwise into the 200 mL O / W emulsion system, and react at room temperature for 12 h to make the tetraethyl orthosilicate hydrolyze and condense to form a silica shell layer at the oil-water interface; the obtained product is centrifuged and washed with ethanol for 3 times, and then dried in a constant temperature oven for 12 h to obtain silica microspheres encapsulating polyethylene glycol modified epoxy resin;

[0039] S3 Polyaniline deposition: take the prepared silica microspheres 2 g, add 100 ml 0.1M hydrochloric acid aqueous solution, ultrasonic 10 min, uniformly dispersed, then add 0.3 g aniline, magnetic stirring uniform, get the mixture; another 0.37 g ammonium persulfate (APs) is added to 100 ml 0.1M hydrochloric acid aqueous solution, ultrasonic dissolution transparent, get ammonium persulfate-hydrochloric acid aqueous solution; by peristaltic pump control, with 30 min ammonium persulfate-hydrochloric acid (APs-HCl) aqueous solution is added to the mixture, under the condition of ice bath reaction 5 h, then stand 2 h, get the reaction product, through the filter, deionized water and ethanol alternative washing, and 80 ℃ vacuum oven drying 24 h, get the powder, that is, the product surface deposition of polyaniline, internal encapsulation of PEG modified epoxy resin and dicyandiamide curing agent self-repairing system of silica microsphere composite material, recorded as PANI-HSMS-E1.

[0040] Example 2

[0041] The present embodiment provides a self-repairing insulation composite material, which is only different from the embodiment 1 in that: in the preparation method thereof, in step S1, the molar ratio of epoxy resin (E-51) and polyethylene glycol (PEG) is 1:1.5; and the prepared composite material is recorded as PANI-HSMS-E2.

[0042] Example 3

[0043] The present embodiment provides a self-repairing insulation composite material, which is only different from the embodiment 1 in that: in the preparation method thereof, in step S3, the weight ratio of aniline and silica microspheres satisfies 0.25:1, that is, taking aniline 0.5 g, silica microspheres 2 g; and the prepared composite material is recorded as PANI-HSMS-E3.

[0044] Comparative Example 1

[0045] The present comparative example provides an insulation material, which is solid silica microspheres, recorded as SS.

[0046] It is prepared by the following method:

[0047] In a beaker, mix 10 milliliters (25-28%) ammonia water and 150 milliliters of anhydrous ethanol and 15 milliliters of deionized water to get solution A;

[0048] Mix 5 milliliters of TEOS and 20 milliliters of anhydrous ethanol in a beaker to get solution B;

[0049] Solution B was quickly added to solution A under high speed magnetic stirring, after 3 min of reaction, the stirring speed was reduced, the flask was sealed, and the reaction was carried out at room temperature for 2 h. The product was centrifuged, washed with ethanol for 3 times, and then placed in a constant temperature oven for drying at 130 °C for 6 h. The product was cooled and sealed for later use.

[0050] Comparative Example 2

[0051] This comparative example provides an insulating material, which is polyaniline deposited solid silica microspheres, denoted as PANI-SS.

[0052] It is prepared by the following method:

[0053] 2 g of SS prepared in Comparative Example 1 was added into 100 ml of 0.1 M hydrochloric acid aqueous solution, and ultrasonically dispersed for 10 min. Then, 0.3 g of aniline was added, and magnetic stirring was started to obtain a mixture. Separately, 0.37 g of APs was added into 100 ml of 0.1 M hydrochloric acid aqueous solution, and ultrasonically dissolved to obtain an APs-HCl aqueous solution. The APs-HCl aqueous solution was added dropwise into the mixture by using a peristaltic pump for 30 min. After the dropwise addition was completed, the reaction was carried out in an ice bath for 5 h, and then the mixture was allowed to stand for 2 h. The greenish solid product was obtained by suction filtration, and washed with deionized water and ethanol alternately until the filtrate was colorless. The greenish solid product was dried in a vacuum oven at 80 °C for 24 h. The obtained powder was polyaniline deposited solid silica (PANI-SS).

[0054] Comparative Example 3

[0055] This comparative example provides an insulating material, which is hollow silica microspheres, denoted as HSMS.

[0056] It is prepared by the following method:

[0057] 20 g of styrene (St) was poured into a high-pressure reaction kettle, 300 g of ethanol / water (2:1) was added, and 0.8 g of azobisdimethylaminoformamide hydrochloride (AIBA) and 10 g of polyvinylpyrrolidone (PVP) were dissolved in the solution and ultrasonically dispersed for 10 min. After heating for 10 h, the centrifuged product was washed with water for 2 times and ethanol for 2 times. The washed product was placed in a constant temperature oven for drying for 12 h to obtain polystyrene (PS) microspheres, which were sealed for later use. The diameter of the obtained PS microspheres was 80 nm. The diameter of the PS microspheres can be adjusted by adjusting the ratio of St, ethanol and water, and the amount of PVP and AIBA.

[0058] Weigh 6 g of PS microspheres (80 nm in diameter) and add them to 1000 ml of ethanol / water (28 ml) solution. Disperse the mixture by sonication for 10 min. Under magnetic stirring, add 45 ml of tetraethyl orthosilicate (TEOS) and 20 ml of ammonia water respectively. After reacting at a constant temperature for 5 h, centrifuge the product, wash it three times with ethanol, and dry it in a constant temperature oven for 12 h to obtain styrene-silica microspheres.

[0059] Styrene-silica microspheres were calcined in a muffle furnace, heated to 550°C at a rate of 5°C / min, held at that temperature for 5 h, cooled and discharged to obtain hollow silica microspheres (HSMS) with a wall thickness of 15 nm, which were then sealed for later use.

[0060] Comparative Example 4

[0061] This comparative example provides an insulating material, which is polyaniline deposited hollow silica microspheres, denoted as PANI-HSMS.

[0062] It is prepared by the following method:

[0063] Take 2 g of HSMS prepared in Comparative Example 3, add it to 100 ml of 0.1 M hydrochloric acid aqueous solution, sonicate for 10 min to disperse evenly, then add 0.3 g of aniline, and then turn on magnetic stirring to stir evenly to obtain a mixture. Separately weigh 0.37 g of APs and add it to 100 ml of 0.1 M hydrochloric acid aqueous solution, sonicate to dissolve until transparent, to obtain APs-HCl aqueous solution. Using a peristaltic pump, add the APs-HCl aqueous solution dropwise to the mixture over 30 min. After the addition is complete, react under ice bath conditions for 5 h, and then let stand for 2 h. Then filter and wash with deionized water and ethanol alternately until the filtrate is colorless. Dry the resulting dark green solid in a vacuum oven at 80 °C for 24 h. The resulting powder is polyaniline deposited hollow silica microspheres (PANI-HSMS).

[0064] Comparative Example 5

[0065] This comparative example provides a self-healing insulating composite material, which differs from Example 1 only in that: in its preparation method, in step S3, the weight ratio of aniline and silica microspheres satisfies 0.6:1, that is, 1.2g of aniline and 2g of silica microspheres are taken; the prepared composite material is denoted as PANI-HSMS-E4.

[0066] Comparative Example 6

[0067] This comparative example serves as a blank example and provides an insulating material, which is an alicyclic epoxy material.

[0068] It is prepared by the following method:

[0069] A mixture of 100 g of 3,4-epoxycyclohexyl carboxylic acid-3,4-epoxycyclohexyl methyl ester cycloaliphatic epoxy resin, 90 g of methyl tetrahydrophthalic anhydride curing agent, 1 g of 2,4,6-tris(dimethylaminomethyl) phenol accelerator, and 220 g of aluminum hydroxide filler was mixed together, and was thoroughly stirred by a stirring disperser. The stirred mixture was introduced into a mold, and was then placed in a vacuum oven at 50-60 °C. The mold was vacuumed at an atmospheric pressure of -0.1 MPa for 30 min to ensure that residual air in the mixture was completely removed.

[0070] After vacuuming, the mold was placed in a constant temperature oven at 120 °C for 10 h to completely cure, and was finally cooled and demolded to obtain the cycloaliphatic epoxy material.

[0071] Comparative Example 7

[0072] This comparative example provides a self-repairing material, which is prepared by the following method:

[0073] First, an oil phase containing 30 g of polyethylene glycol modified epoxy resin and 2.5 g of micronized dicyandiamide dissolved in 100 mL of toluene was stirred to be clear in a 50-60 °C water bath. Then, 0.5 g of sodium dodecyl sulfate (SDS) was dissolved in 90 mL of deionized water, and 10 mL of 0.1M hydrochloric acid solution was added as an aqueous phase. The oil phase was slowly added to the aqueous phase under high-speed shearing (10000-15000 rpm) conditions to form an oil / water emulsion (droplet size 1-10 μm) for 5-10 min. After the emulsion was transferred to a three-necked flask, 1.8 g of water-soluble chain extender ethylenediamine (dissolved in 10-20 mL of water) was added to the system. After being warmed to 50-60 °C, 5.0 g of diisocyanate (TDI, dissolved in 10-20 mL of toluene) was slowly added (30-60 min for dropwise addition) to the emulsion through a constant pressure dropping funnel under mechanical stirring at 300-500 rpm. After the addition was completed, the reaction was continued at 50-60 °C for 4-6 h to allow the isocyanate and amine chain extender to fully polymerize at the oil-water interface to form a dense polyurethane wall layer. After the reaction was completed, centrifugal separation (4000 rpm, 10 min) was performed, and the product was washed with anhydrous ethanol and deionized water alternately for 3 times, and finally vacuum dried at 40-50 °C for 12-24 h to obtain a polyurethane-coated microcapsule product, which is denoted as PU-E.

[0074] Test Example

[0075] The cycloaliphatic epoxy material provided in Comparative Example 6 was used as a matrix, and the insulating materials provided in Examples 1-3 and Comparative Examples 1-5 and the self-repairing material provided in Comparative Example 7 were added respectively to prepare composite insulating materials, and the obtained composite insulating materials were tested for performance.

[0076] The raw material ratio of each group of composite insulating materials is shown in Table 1:

[0077] Table 1 Raw material ratio of each experimental example

[0078]

[0079] Test items and test methods are as follows:

[0080] Impact resistance: test the impact strength according to ISO 179-1 / 1eU, place the sample horizontally on two support seats, make sure the long axis direction of the sample is perpendicular to the support line. The impact surface of the sample should face the pendulum. Adjust the support span according to the thickness of the sample. For example: thickness 4 mm sample: span is 62 mm (ISO 179 specifies span as 16 times thickness, i.e. 4x16=64 mm, which is actually simplified to 62 mm). Lift the pendulum to the standard starting height (energy scale zero). Release the pendulum to fall freely, impact the center position of the sample. Record the remaining energy of the pendulum after breaking the sample (or energy loss value).

[0081] Volume resistivity: measure the volume resistivity of the sample by high resistance meter (6517A) produced by American Keithley Company, test by three electrode method, sample box is Model 8009, test voltage is 500 V, test temperature is 20℃, sample thickness is 1 mm. For high insulation materials, at the initial stage of applying voltage, the current is mainly polarization current, and with the extension of time, the polarization is completed, at this time the current is mainly caused by impurity ions. In order to reduce the polarization current and the interference of environmental factors, when testing the resistivity, the time required for the current to stabilize needs to be determined first. Apply 500 V voltage to the sample for a period of time, and the current stabilizes after 50 s. In the following experiment, 150 s is taken as the stabilization time. Each sample is tested for 5 cycles, and the average value is taken as the volume resistivity of the sample.

[0082] Dielectric strength: measure the dielectric constant and dielectric loss of the composite material by precision impedance analyzer (4294A) produced by American Agilent, test temperature is 20℃, test voltage is 0.5 V, test frequency is 40-106 Hz, sample thickness is 1 mm.

[0083] Self-repairing performance test: prepare epoxy resin standard sample containing composite filler (size 100x10x2 mm), use diamond blade to prepare standard crack (width 100±5 μm, depth 1 mm), place the damaged sample in 80℃ oven for 2h, naturally cool to room temperature and stand for 24h. Measure the dielectric constant and dielectric loss of the composite material before and after damage by precision impedance analyzer (4294A) produced by American Agilent.

[0084] The test results are shown in Tables 2 and 3.

[0085] Table 2: Mechanical and electrical properties of each experimental example

[0086]

[0087] Table 3: Self-repairing properties of each experimental example

[0088]

[0089] It can be seen from the results that the PANI-HSMS-E material prepared by the embodiment of the application can effectively improve the mechanical and insulating properties of the insulating material when applied to the composite insulating material, and at the same time, the material is endowed with self-repairing ability, and has excellent performance.

[0090] In summary, the embodiment of the application provides a self-repairing insulating composite material and a preparation method thereof, which not only solves the contradiction between light weight and high reliability of traditional insulating materials, but also realizes the synergistic optimization of "self-repairing-electric field regulation-interface stability" through multi-functional integration, provides a breakthrough insulating material solution for new energy automobile motor, high-voltage direct current cable and other application scenarios, and promotes the development of electronic and electrical equipment to be more efficient and more reliable.

[0091] The above-described embodiments are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

Claims

1. A self-healing insulating composite material, characterized in that, Its structure includes a self-healing core system, an insulating core, and a dielectric shell arranged sequentially from the inside out; The insulating core is a hollow silica microsphere, the self-healing core system includes polyethylene glycol modified epoxy resin and dicyandiamide, and the dielectric shell is composed of polyaniline nanoparticles. The hollow silica microspheres contain the self-healing core system encapsulated within their internal cavities. The hollow silica microspheres are deposited with polyaniline nanoparticles to form the dielectric shell. The specific steps for depositing polyaniline nanoparticles on the surface of hollow silica microspheres include: taking the prepared silica microspheres, adding them to a hydrochloric acid aqueous solution, dispersing them by ultrasound, then adding aniline and stirring to obtain a mixture; separately taking ammonium persulfate and adding it to a hydrochloric acid aqueous solution, dissolving it by ultrasound to obtain an ammonium persulfate-hydrochloric acid aqueous solution; adding the ammonium persulfate-hydrochloric acid aqueous solution dropwise to the mixture to react and obtain a reaction product, which is then filtered, washed, and dried to obtain the finished product; wherein, the weight ratio of aniline to silica microspheres satisfies 0.15~0.25:

1.

2. The self-healing insulating composite material according to claim 1, characterized in that, The insulating core has a particle size of 70–90 nm and a wall thickness of 15–25 nm, and its wall layer is composed of silica particles with a particle size of 5–10 nm.

3. The self-healing insulating composite material according to claim 1, characterized in that, The dielectric shell is composed of polyaniline nanoparticles with a particle size of 1-3 nm, and the distribution area of ​​the polyaniline nanoparticles accounts for 20-25% of the surface area of ​​the hollow silica microspheres.

4. A method for preparing a self-healing insulating composite material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1 Preparation of polyethylene glycol modified epoxy resin: Epoxy resin and polyethylene glycol are reacted under the action of a catalyst to prepare polyethylene glycol modified epoxy resin. Preparation of S2 silica microspheres: The prepared polyethylene glycol modified epoxy resin and micronized dicyandiamide were dissolved together in toluene as the oil phase; a solution containing hydrochloric acid and sodium dodecyl sulfonate was used as the aqueous phase; An O / W emulsion system was formed by high-speed shear emulsification, and tetraethyl orthosilicate was added dropwise to the O / W emulsion system to react, causing the tetraethyl orthosilicate to hydrolyze and condense at the oil-water interface to form a silica shell; the obtained product was centrifuged, washed with ethanol, and dried to obtain silica microspheres encapsulated with polyethylene glycol modified epoxy resin. S3 Polyaniline Deposition: Take the prepared silica microspheres, add them to hydrochloric acid aqueous solution, disperse them by ultrasound, then add aniline and stir to obtain a mixture; separately take ammonium persulfate and add it to hydrochloric acid aqueous solution, dissolve it by ultrasound to obtain ammonium persulfate-hydrochloric acid aqueous solution; add the ammonium persulfate-hydrochloric acid aqueous solution dropwise to the mixture to react and obtain the reaction product, which is then filtered, washed and dried to obtain the finished product.

5. The method for preparing the self-healing insulating composite material according to claim 4, characterized in that, In step S1, the molar ratio of epoxy resin to polyethylene glycol is 1:0.8 to 1:1.

5.

6. The method for preparing the self-healing insulating composite material according to claim 4, characterized in that, In step S2, during the process of forming an O / W emulsion system through high-speed shear emulsification, fumed silica is added to prevent sedimentation.

7. The method for preparing the self-healing insulating composite material according to claim 6, characterized in that, In step S2, the prepared polyethylene glycol modified epoxy resin and 5-10 wt% micronized dicyandiamide are co-dissolved in toluene as the oil phase; An O / W emulsion system was formed by emulsifying a solution containing 0.1 M hydrochloric acid and 0.5 wt% sodium dodecyl sulfonate as the aqueous phase, with an additional 1 wt% fumed silica added, through high-speed shear emulsification.

8. The method for preparing the self-healing insulating composite material according to claim 4, characterized in that, In step S2, the diameter of the emulsion droplets in the formed O / W emulsion system is 200–500 nm.

9. The method for preparing the self-healing insulating composite material according to claim 4, characterized in that, In step S2, tetraethyl orthosilicate is added dropwise to the O / W emulsion system at room temperature to carry out the reaction.

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