Preparation method of epoxy resin insulating material for transformer iron core

Abstract

The invention belongs to the technical field of iron cores, and particularly relates to a preparation method of an epoxy resin insulating material for a transformer iron core, and the epoxy resin insulating material comprises the following components in parts by mass: 30-40 parts of epoxy resin, 20-30 parts of an epoxy resin curing agent, 20-30 parts of modified expanded vermiculite, 10-20 parts of a film-forming agent and 2-4 parts of active POSS (Polyhedral Oligomeric Silsesquioxane). The modified expanded vermiculite adopts heat-conducting modified expanded vermiculite, and a specific preparation method is provided. The problem of local deterioration of the adhesive of the laminated iron core is solved, the heat conduction efficiency of the epoxy resin is improved by utilizing the heat conduction modified expanded vermiculite, the influence of local high temperature is reduced, and meanwhile, the overall insulating property is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of iron cores, and in particular relates to a method for preparing an epoxy resin insulating material for a transformer iron core. Background Art

[0002] Transformer lamination technology utilizes a multi-layer, thin-plate core to achieve high-density wiring within a compact space, enabling efficient and reliable energy conversion. Traditional transformer cores utilize a single-layer core. Laminated cores consist of multiple thin laminations stacked together. Electrical energy is transferred through coils wound around the core, and energy transfer is achieved through the magnetic core. Therefore, laminated cores offer advantages such as simple structure, material conservation, compact size, and low energy consumption, making them a mainstream technology in modern transformer manufacturing. Current laminated cores are manufactured by etching, polishing, flattening, and coating multiple laminations before being laminated using automated lamination lines. However, laminated cores are secured by adhesives, and adjacent laminations are insulated by the adhesive. Over long-term use, the surface temperature of the laminated core rises, even experiencing localized high temperatures. This can cause the adhesive between adjacent laminations to deteriorate, leading to changes in adhesion and insulation properties. Summary of the Invention

[0003] In response to the problems in the prior art, the present invention provides a method for preparing epoxy resin insulation material for transformer cores, which solves the problem of local deterioration of the adhesive of the laminated core. The thermally conductive modified expanded vermiculite is used to improve the thermal conductivity of the epoxy resin, reduce the impact of local high temperature, and improve the overall insulation performance.

[0004] In order to achieve the above technical objectives, the technical solution of the present invention is: The invention discloses a preparation method of an epoxy resin insulation material for a transformer core. The epoxy resin insulation material comprises the following mass ratios: 30-40 parts of epoxy resin, 20-30 parts of epoxy resin curing agent, 20-30 parts of modified expanded vermiculite, 10-20 parts of film-forming agent and 2-4 parts of active POSS.

[0005] The epoxy resin is a bisphenol A epoxy resin, specifically one of E-51, E-44, and E-20. Bisphenol A epoxy resin has excellent insulation properties, chemical corrosion resistance, hydrolysis resistance, and heat resistance. Furthermore, after curing, the bisphenol A epoxy resin has good hardness, strength, and toughness.

[0006] The epoxy resin curing agent is methyltetrahydrophthalic anhydride.

[0007] The modified expanded vermiculite is heat-conducting modified expanded vermiculite. Expanded vermiculite is vermiculite that has expanded several to dozens of times in volume after high-temperature roasting. The expanded vermiculite expands as the internal moisture evaporates, forming a layered porous structure. However, the material properties and porosity of the expanded vermiculite prevent the thermal insulation effect of the heat-conducting system, making it difficult to achieve rapid local heat transfer. To address this problem, the expanded vermiculite is treated to be heat-conducting. Through modification, a heat-conducting material is adsorbed on the surface of the expanded vermiculite, forming a heat-conducting network system. This achieves heat transfer within the coating and eliminates the problem of localized high temperatures. The heat-conducting modified expanded vermiculite is modified with alumina to form an alumina heat-conducting network.The preparation method of the thermally conductive modified expanded vermiculite comprises the following steps: a1, grinding the expanded vermiculite for 30 minutes, and obtaining expanded vermiculite particles with uniform particle size after sieving, wherein the grinding pressure is 0.5 MPa, the temperature is not higher than 30° C., and the sieve is 50 mesh. In this step, the particle size of the expanded vermiculite particles is refined by grinding, and expanded vermiculite with a relatively close particle size is selected in the subsequent sieving; a2, ultrasonically cleaning the expanded vermiculite in ethanol, filtering, and drying to obtain clean expanded vermiculite particles with distinct particle sizes, wherein the mass ratio of the expanded vermiculite to ethanol is 1:6. , the ultrasonic frequency of ultrasonic cleaning is 80kHz, the temperature is 20°C, and the drying temperature is 100°C. This step completely opens the pore structure in the expanded vermiculite by ultrasonic cleaning to ensure the permeability of the pore structure, and then the small particles peeled off are dispersed during filtration; a3, aluminum isopropylate and ethanol are mixed evenly and introduced into a reactor containing expanded vermiculite, and humid air is purged after constant temperature standing to obtain hydrolysis-modified expanded vermiculite, the volume ratio of aluminum isopropylate to ethanol is 1:3, the introduction temperature is 145°C, the mass ratio of aluminum isopropylate to expanded vermiculite is 4:3, constant temperature standing The temperature of the humid air is 125°C, the humidity of the humid air is 75%, and the purge speed is 10mL / min. This step uses ethanol as a diluent to convert aluminum isopropylate into a solution, and converts it into steam and enters the reactor. At this time, the expanded vermiculite adsorbs aluminum isopropylate and liquid-deposits it on the surface. As the standing temperature changes, the gaseous aluminum isopropylate is converted into a liquid state and forms a surface liquid film. After being purged with humid air, the aluminum isopropylate is in situ hydrolyzed to form aluminum hydroxide; a4, the hydrolysis-modified expanded vermiculite is subjected to a constant temperature sintering treatment for 2h, and the constant temperature is allowed to stand for 1h to obtain alumina-modified expanded vermiculite. The constant temperature sintering The temperature of the sintering treatment is 300° C., and the temperature of the constant temperature static state is 130° C. In this step, aluminum isopropylate is converted into aluminum oxide by constant temperature sintering, and the aluminum isopropylate liquid film is converted into aluminum hydroxide in situ, and finally an aluminum oxide film is formed. The alumina-modified expanded vermiculite prepared by this method utilizes the insulation properties of expanded vermiculite and alumina to ensure the insulation properties of epoxy resin, and forms a heat conduction network with the thermal conductivity of alumina to solve the problem of local temperature. At the same time, the alumina-modified expanded vermiculite is based on expanded vermiculite and has porosity, which, in combination with the permeability of epoxy resin, ensures the curing properties of the alumina-modified expanded vermiculite.

[0008] The film-forming agent is a mixture of propylene glycol butyl ether and propylene glycol propyl ether, and the volume ratio of propylene glycol butyl ether to propylene glycol propyl ether is 2:2-3; propylene glycol butyl ether and propylene glycol propyl ether are both good solubilizers, forming good dispersibility and fluidity for epoxy resin, thereby ensuring the film-forming performance of epoxy resin on the thin plate iron core.

[0009] The active POSS adopts octaammonium cage-type silsesquioxane.

[0010] The preparation method of the epoxy resin insulating material comprises the following steps: Step 1: Evenly stir the epoxy resin, epoxy resin curing agent, and film-forming agent, and obtain a mixed resin after vacuum degassing at a stirring speed of 100-400 r / min; Step 2, blending the modified expanded vermiculite and the active POSS, and adding them to the mixed resin and stirring at room temperature to obtain a prefabricated coating; the stirring speed at room temperature is 1000-2000 r / min; Step 3: vacuum degas the pre-coated coating and pre-cure it for 1 hour, then heat cure it for 1 hour, and naturally cool it to obtain the epoxy resin insulation material. The pre-curing temperature is 70-80°C, and the heat cure temperature is 120-140°C.

[0011] It can be seen from the above description that the present invention has the following advantages: 1. This invention solves the problem of local deterioration of the adhesive in laminated cores by utilizing thermally conductive modified expanded vermiculite to improve the thermal conductivity of epoxy resin, reduce the impact of local high temperatures, and improve overall insulation performance. 2. The present invention utilizes active POSS as a dopant and blends it with thermally conductive modified expanded vermiculite. Combined with its own low particle size and permeability, it can fill the pore structure within the expanded vermiculite and form infiltration with epoxy resin under dilution of a film-forming agent, thereby obtaining an integrated dense structure. 3. The present invention utilizes the gas-liquid changes of aluminum isopropoxide in combination with the adsorption properties of expanded vermiculite to adsorb aluminum isopropoxide in situ on the expanded vermiculite. The exposed hydrophilic groups in the expanded vermiculite are reduced through a hydrolysis and polycondensation reaction, thereby achieving the purpose of improving the hydrophilicity and water absorption of the expanded vermiculite and enhancing the stability and tightness of the adhesive. DETAILED DESCRIPTION

[0012] The present invention is described in detail with reference to the embodiments, but no limitation is imposed on the claims of the present invention. Example 1

[0013] The invention discloses a preparation method of an epoxy resin insulation material for a transformer core. The epoxy resin insulation material comprises the following mass ratios: 30 parts of epoxy resin, 20 parts of epoxy resin curing agent, 30 parts of modified expanded vermiculite, 10 parts of film-forming agent and 4 parts of active POSS.

[0014] The epoxy resin is bisphenol A type epoxy resin E-51.

[0015] The epoxy resin curing agent is methyltetrahydrophthalic anhydride.

[0016] The modified expanded vermiculite adopts thermally conductive modified expanded vermiculite; the preparation method of the thermally conductive modified expanded vermiculite comprises the following steps: a1, grinding the expanded vermiculite for 30 minutes, and obtaining expanded vermiculite particles with uniform particle size after sieving, wherein the grinding pressure is 0.5 MPa, the temperature is not higher than 30° C., and the sieve is 50 mesh; a2, ultrasonically cleaning the expanded vermiculite in ethanol, filtering, and drying to obtain clean expanded vermiculite particles with distinct particle size, wherein the mass ratio of the expanded vermiculite to ethanol is 1:6, the ultrasonic cleaning frequency is 80 kHz, the temperature is 20° C., and the drying temperature is 100° C.; a3, Aluminum isopropoxide and ethanol are uniformly mixed and introduced into a reactor containing expanded vermiculite. After standing at a constant temperature, moist air is purged to obtain hydrolysis-modified expanded vermiculite. The volume ratio of aluminum isopropoxide to ethanol is 1:3, the introduction temperature is 145°C, the mass ratio of aluminum isopropoxide to expanded vermiculite is 4:3, the constant temperature standing temperature is 125°C, the humidity of the moist air is 75%, and the purge rate is 10 mL / min. a4. The hydrolysis-modified expanded vermiculite is subjected to a constant temperature sintering treatment for 2 h and allowed to stand at a constant temperature for 1 h to obtain alumina-modified expanded vermiculite. The constant temperature sintering treatment temperature is 300°C, and the constant temperature standing temperature is 130°C.

[0017] The film-forming agent is a mixture of propylene glycol butyl ether and propylene glycol propyl ether, and the volume ratio of propylene glycol butyl ether to propylene glycol propyl ether is 2:2.

[0018] The active POSS adopts octaammonium cage-type silsesquioxane.

[0019] The preparation method of the epoxy resin insulating material comprises the following steps: Step 1, mixing epoxy resin, epoxy resin curing agent, and film-forming agent uniformly, and obtaining a mixed resin after vacuum degassing, wherein the stirring speed is 100 r / min; Step 2, blending the modified expanded vermiculite and the active POSS, and adding them to the mixed resin and stirring at room temperature to obtain a prefabricated coating; the stirring speed at room temperature is 1000 r / min; Step 3: vacuum degas the pre-coated coating and then pre-cure it for 1 hour, then heat cure it for 1 hour, and naturally cool it to obtain the epoxy resin insulation material. The pre-curing temperature is 70°C and the heat cure temperature is 120°C. Example 2

[0020] The invention discloses a preparation method of an epoxy resin insulation material for a transformer core. The epoxy resin insulation material comprises the following mass ratios: 40 parts of epoxy resin, 30 parts of epoxy resin curing agent, 20 parts of modified expanded vermiculite, 15 parts of film-forming agent and 4 parts of active POSS.

[0021] The epoxy resin is bisphenol A type epoxy resin E-44.

[0022] The epoxy resin curing agent is methyltetrahydrophthalic anhydride.

[0023] The modified expanded vermiculite adopts thermally conductive modified expanded vermiculite; the preparation method of the thermally conductive modified expanded vermiculite comprises the following steps: a1, grinding the expanded vermiculite for 30 minutes, and obtaining expanded vermiculite particles with uniform particle size after sieving, wherein the grinding pressure is 0.5 MPa, the temperature is not higher than 30° C., and the sieve is 50 mesh; a2, ultrasonically cleaning the expanded vermiculite in ethanol, filtering, and drying to obtain clean expanded vermiculite particles with distinct particle size, wherein the mass ratio of the expanded vermiculite to ethanol is 1:6, the ultrasonic cleaning frequency is 80 kHz, the temperature is 20° C., and the drying temperature is 100° C.; a3, Aluminum isopropoxide and ethanol are uniformly mixed and introduced into a reactor containing expanded vermiculite. After standing at a constant temperature, moist air is purged to obtain hydrolysis-modified expanded vermiculite. The volume ratio of aluminum isopropoxide to ethanol is 1:3, the introduction temperature is 145°C, the mass ratio of aluminum isopropoxide to expanded vermiculite is 4:3, the constant temperature standing temperature is 125°C, the humidity of the moist air is 75%, and the purge rate is 10 mL / min. a4. The hydrolysis-modified expanded vermiculite is subjected to a constant temperature sintering treatment for 2 h and allowed to stand at a constant temperature for 1 h to obtain alumina-modified expanded vermiculite. The constant temperature sintering treatment temperature is 300°C, and the constant temperature standing temperature is 130°C.

[0024] The film-forming agent is a mixture of propylene glycol butyl ether and propylene glycol propyl ether, and the volume ratio of propylene glycol butyl ether to propylene glycol propyl ether is 2:3.

[0025] The active POSS adopts octaammonium cage-type silsesquioxane.

[0026] The preparation method of the epoxy resin insulating material comprises the following steps: Step 1, mixing epoxy resin, epoxy resin curing agent, and film-forming agent uniformly, and obtaining a mixed resin after vacuum degassing, wherein the stirring speed is 400 r / min; Step 2, blending the modified expanded vermiculite and the active POSS, and adding them to the mixed resin and stirring at room temperature to obtain a prefabricated coating; the stirring speed at room temperature is 2000 r / min; Step 3: vacuum degas the pre-coated coating and pre-cure it for 1 hour, then heat cure it for 1 hour, and naturally cool it to obtain the epoxy resin insulation material. The pre-curing temperature is 80° C. and the heat cure temperature is 140° C. Example 3

[0027] The invention discloses a preparation method of an epoxy resin insulation material for a transformer core. The epoxy resin insulation material comprises the following mass ratios: 35 parts of epoxy resin, 25 parts of epoxy resin curing agent, 25 parts of modified expanded vermiculite, 20 parts of film-forming agent and 3 parts of active POSS.

[0028] The epoxy resin is bisphenol A type epoxy resin E-20.

[0029] The epoxy resin curing agent is methyltetrahydrophthalic anhydride.

[0030] The modified expanded vermiculite adopts thermally conductive modified expanded vermiculite; the preparation method of the thermally conductive modified expanded vermiculite comprises the following steps: a1, grinding the expanded vermiculite for 30 minutes, and obtaining expanded vermiculite particles with uniform particle size after sieving, wherein the grinding pressure is 0.5 MPa, the temperature is not higher than 30° C., and the sieve is 50 mesh; a2, ultrasonically cleaning the expanded vermiculite in ethanol, filtering, and drying to obtain clean expanded vermiculite particles with distinct particle size, wherein the mass ratio of the expanded vermiculite to ethanol is 1:6, the ultrasonic cleaning frequency is 80 kHz, the temperature is 20° C., and the drying temperature is 100° C.; a3, Aluminum isopropoxide and ethanol are uniformly mixed and introduced into a reactor containing expanded vermiculite. After standing at a constant temperature, moist air is purged to obtain hydrolysis-modified expanded vermiculite. The volume ratio of aluminum isopropoxide to ethanol is 1:3, the introduction temperature is 145°C, the mass ratio of aluminum isopropoxide to expanded vermiculite is 4:3, the constant temperature standing temperature is 125°C, the humidity of the moist air is 75%, and the purge rate is 10 mL / min. a4. The hydrolysis-modified expanded vermiculite is subjected to a constant temperature sintering treatment for 2 h and allowed to stand at a constant temperature for 1 h to obtain alumina-modified expanded vermiculite. The constant temperature sintering treatment temperature is 300°C, and the constant temperature standing temperature is 130°C.

[0031] The film-forming agent is a mixture of propylene glycol butyl ether and propylene glycol propyl ether, and the volume ratio of propylene glycol butyl ether to propylene glycol propyl ether is 2:2.

[0032] The active POSS adopts octaammonium cage-type silsesquioxane.

[0033] The preparation method of the epoxy resin insulating material comprises the following steps: Step 1, mixing epoxy resin, epoxy resin curing agent, and film-forming agent uniformly, and obtaining a mixed resin after vacuum degassing, wherein the stirring speed is 300 r / min; Step 2, blending the modified expanded vermiculite and the active POSS, and adding them to the mixed resin and stirring at room temperature to obtain a prefabricated coating; the stirring speed at room temperature is 1500 r / min; Step 3: vacuum degas the pre-coated coating and then pre-cure it for 1 hour, then heat cure it for 1 hour, and naturally cool it to obtain the epoxy resin insulation material. The pre-curing temperature is 75° C. and the heat cure temperature is 130° C.

[0034] Comparative Example 1 The invention discloses a preparation method of an epoxy resin insulation material for a transformer core. The epoxy resin insulation material comprises the following mass ratios: 35 parts of epoxy resin, 25 parts of epoxy resin curing agent, 25 parts of expanded vermiculite, 20 parts of film-forming agent and 3 parts of active POSS.

[0035] The epoxy resin is bisphenol A type epoxy resin E-20.

[0036] The epoxy resin curing agent is methyltetrahydrophthalic anhydride.

[0037] The film-forming agent is a mixture of propylene glycol butyl ether and propylene glycol propyl ether, and the volume ratio of propylene glycol butyl ether to propylene glycol propyl ether is 2:2.

[0038] The active POSS adopts octaammonium cage-type silsesquioxane.

[0039] The preparation method of the epoxy resin insulating material comprises the following steps: Step 1, mixing epoxy resin, epoxy resin curing agent, and film-forming agent uniformly, and obtaining a mixed resin after vacuum degassing, wherein the stirring speed is 300 r / min; Step 2, blending the modified expanded vermiculite and the active POSS, and adding them to the mixed resin and stirring at room temperature to obtain a prefabricated coating; the stirring speed at room temperature is 1500 r / min; Step 3: vacuum degas the pre-coated coating and then pre-cure it for 1 hour, then heat cure it for 1 hour, and naturally cool it to obtain the epoxy resin insulation material. The pre-curing temperature is 75° C. and the heat cure temperature is 130° C.

[0040] Comparative Example 2 A method for preparing an epoxy resin insulation material for a transformer core. The epoxy resin insulation material comprises the following mass ratios: 35 parts of epoxy resin, 25 parts of epoxy resin curing agent, 25 parts of modified expanded vermiculite, and 20 parts of film-forming agent.

[0041] The epoxy resin is bisphenol A type epoxy resin E-20.

[0042] The epoxy resin curing agent is methyltetrahydrophthalic anhydride.

[0043] The modified expanded vermiculite adopts thermally conductive modified expanded vermiculite; the preparation method of the thermally conductive modified expanded vermiculite comprises the following steps: a1, grinding the expanded vermiculite for 30 minutes, and obtaining expanded vermiculite particles with uniform particle size after sieving, wherein the grinding pressure is 0.5 MPa, the temperature is not higher than 30° C., and the sieve is 50 mesh; a2, ultrasonically cleaning the expanded vermiculite in ethanol, filtering, and drying to obtain clean expanded vermiculite particles with distinct particle size, wherein the mass ratio of the expanded vermiculite to ethanol is 1:6, the ultrasonic cleaning frequency is 80 kHz, the temperature is 20° C., and the drying temperature is 100° C.; a3, Aluminum isopropoxide and ethanol are uniformly mixed and introduced into a reactor containing expanded vermiculite. After standing at a constant temperature, moist air is purged to obtain hydrolysis-modified expanded vermiculite. The volume ratio of aluminum isopropoxide to ethanol is 1:3, the introduction temperature is 145°C, the mass ratio of aluminum isopropoxide to expanded vermiculite is 4:3, the constant temperature standing temperature is 125°C, the humidity of the moist air is 75%, and the purge rate is 10 mL / min. a4. The hydrolysis-modified expanded vermiculite is subjected to a constant temperature sintering treatment for 2 h and allowed to stand at a constant temperature for 1 h to obtain alumina-modified expanded vermiculite. The constant temperature sintering treatment temperature is 300°C, and the constant temperature standing temperature is 130°C.

[0044] The film-forming agent is a mixture of propylene glycol butyl ether and propylene glycol propyl ether, and the volume ratio of propylene glycol butyl ether to propylene glycol propyl ether is 2:2.

[0045] The preparation method of the epoxy resin insulating material comprises the following steps: Step 1, mixing epoxy resin, epoxy resin curing agent, and film-forming agent uniformly, and obtaining a mixed resin after vacuum degassing, wherein the stirring speed is 300 r / min; Step 2, blending the modified expanded vermiculite and the active POSS, and adding them to the mixed resin and stirring at room temperature to obtain a prefabricated coating; the stirring speed at room temperature is 1500 r / min; Step 3: vacuum degas the pre-coated coating and then pre-cure it for 1 hour, then heat cure it for 1 hour, and naturally cool it to obtain the epoxy resin insulation material. The pre-curing temperature is 75° C. and the heat cure temperature is 130° C.

[0046] Performance testing The products of Examples 1-3 and Comparative Examples 1-2 were used as test samples for performance testing, and the results are as follows: Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Adhesion Level 0 Level 0 Level 0 Level 0 Level 0 Thermal conductivity 0.59W / (m·K) 0.63W / (m·K) 0.61W / (m·K) 0.12W / (m·K) 0.13W / (m·K) wear resistance 0.04mg 0.03mg 0.03mg 0.07mg 0.06mg The comparison of the above data shows that this embodiment uses aluminum oxide as a conductive agent, which is evenly distributed on the surface of vermiculite to form a surface thermal conductivity network, thereby improving the thermal conductivity of expanded vermiculite, reducing the high-temperature aging problem caused by local high temperature, and extending the service life of epoxy resin insulation materials. The improvement of thermal conductivity can accelerate heat flow and reduce the risk of iron core breakdown. At the same time, the porous structure and surface wear resistance of expanded vermiculite are improved, and the surface activity of aluminum oxide is used to improve the overall adhesion and internal stability, improving the problem of reduced mechanical properties caused by expanded vermiculite, and using the wear resistance of aluminum oxide and expanded vermiculite to improve the insulation wear resistance of the entire epoxy resin, thereby improving the stability and service life of the insulation material. Expanded vermiculite, aluminum oxide and epoxy resin are all insulating materials, which can effectively ensure the insulation properties of the overall material and form an excellent insulation barrier effect between the core laminations.

[0047] It is understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced with equivalents to achieve the same technical effects; as long as the use requirements are met, they are all within the scope of protection of the present invention.

Claims

1. A method for preparing an epoxy resin insulation material for a transformer core, characterized in that: The mass ratio of the epoxy resin insulation material is: 30-40 parts of epoxy resin, 20-30 parts of epoxy resin curing agent, 20-30 parts of modified expanded vermiculite, 10-20 parts of film-forming agent, and 2-4 parts of active POSS; the modified expanded vermiculite is thermally conductive modified expanded vermiculite.

2. The method for preparing the epoxy resin insulation material for transformer core according to claim 1, wherein: The epoxy resin is bisphenol A type epoxy resin, specifically one of E-51, E-44 and E-20.

3. The method for preparing the epoxy resin insulation material for transformer core according to claim 1, wherein: The epoxy resin curing agent is methyltetrahydrophthalic anhydride.

4. The method for preparing the epoxy resin insulation material for transformer core according to claim 1, wherein: The thermally conductive modified expanded vermiculite is aluminum oxide modified expanded vermiculite.

5. The method for preparing the epoxy resin insulation material for transformer core according to claim 1, wherein: The film-forming agent is a mixture of propylene glycol butyl ether and propylene glycol propyl ether, and the volume ratio of propylene glycol butyl ether to propylene glycol propyl ether is 2:2-3.

6. The method for preparing the epoxy resin insulation material for transformer core according to claim 1, wherein: The active POSS adopts octaammonium cage-type silsesquioxane.

7. The method for preparing the epoxy resin insulation material for transformer core according to claim 1, characterized in that: The preparation method of the epoxy resin insulating material comprises the following steps: Step 1: Evenly stir the epoxy resin, epoxy resin curing agent, and film-forming agent, and obtain a mixed resin after vacuum degassing at a stirring speed of 100-400 r / min; Step 2, blending the modified expanded vermiculite and the active POSS, and adding them to the mixed resin and stirring at room temperature to obtain a prefabricated coating; the stirring speed at room temperature is 1000-2000 r / min; Step 3: vacuum degas the pre-coated coating and then pre-cure it for 1 hour, then heat and cure it for 1 hour, and then naturally cool it to obtain the epoxy resin insulation material.

8. The method for preparing the epoxy resin insulation material for transformer core according to claim 7, characterized in that: The pre-curing temperature in step 3 is 70-80°C, and the curing temperature is 120-140°C.