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CN-121975271-A - Epoxy resin castable for solid-state transformer and preparation method thereof

CN121975271ACN 121975271 ACN121975271 ACN 121975271ACN-121975271-A

Abstract

The application provides a method for preparing an epoxy resin castable for a solid-state transformer, which comprises the steps of providing 100 parts of epoxy resin, 80-120 parts of anhydride curing agent, 150-300 parts of functionalized heat conducting filler, 0.1-0.5 part of click reaction catalyst and 0.5-2 parts of curing accelerator, vacuum defoaming the functionalized heat conducting filler, the click reaction catalyst and the epoxy resin at 50-60 ℃, heating to 70-80 ℃ to enable mercapto and alkenyl to perform click reaction to obtain a premix, adding the anhydride curing agent and the curing accelerator, mixing, defoaming, and casting and curing. According to the method, through the stepwise design of constructing covalent skeletons among fillers and then anchoring the covalent skeletons to resin, an isotropy distributed three-dimensional rigid network is formed, and the method is favorable for restraining the thermal expansion behavior of a resin matrix, so that the thermal expansion coefficient is reduced, the anisotropy is reduced, and the castable has good thermal cycle stability.

Inventors

  • LV HONGLIANG
  • CHEN TIANBIAO

Assignees

  • 湖北江特绝缘材料有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. A method of preparing an epoxy casting material for a solid state transformer, comprising the steps of: Providing 100 parts of epoxy resin, 80-120 parts of anhydride curing agent, 150-300 parts of functionalized heat conducting filler, 0.1-0.5 part of click reaction catalyst and 0.5-2 parts of curing accelerator as raw materials, wherein the functionalized heat conducting filler comprises mercapto-modified one-dimensional heat conducting filler, alkenyl epoxy co-modified two-dimensional heat conducting filler and epoxy-modified zero-dimensional heat conducting filler; M2, stirring and defoaming the functionalized heat conducting filler, the click reaction catalyst and the epoxy resin in vacuum at 50-60 ℃ for 10-30 min, maintaining stirring and heating to 70-80 ℃ and mixing for 10-20 min, so that the mercapto on the surface of the mercapto modified one-dimensional heat conducting filler and the alkenyl on the surface of the alkenyl epoxy co-modified two-dimensional heat conducting filler undergo click chemical reaction to obtain a premix; M3, adding an anhydride curing agent and a curing accelerator into the premix, stirring and mixing under a vacuum condition, and removing bubbles to obtain a mixture; and M4, pouring the mixture into a preheated solid-state transformer winding die, and curing to obtain the epoxy resin castable.
  2. 2. The method of claim 1, wherein the mercapto-modified one-dimensional heat-conducting filler is prepared by dispersing 5-15 parts of gamma-mercaptopropyl trimethoxy silane in 100-150 parts of ethanol aqueous solution, prehydrolyzing for 20-40 min at 40-60 ℃, adding 100 parts of one-dimensional heat-conducting filler, and reacting for 4-8 h at 70-90 ℃ to obtain the mercapto-modified one-dimensional heat-conducting filler.
  3. 3. The method of claim 2, wherein the one-dimensional thermally conductive filler is a needle-like or linear silicon nitride whisker or silicon carbide whisker.
  4. 4. The method of claim 1, wherein the alkenyl epoxy co-modified two-dimensional heat conducting filler is prepared by dispersing 3-8 parts of vinyl triethoxysilane and 3-8 parts of gamma-glycidoxypropyl trimethoxysilane in 100-150 parts of ethanol aqueous solution, adjusting pH to 4-5, prehydrolyzing at 40-60 ℃ for 20-40 min, adding 100 parts of two-dimensional heat conducting filler, and reacting at 70-90 ℃ for 4-8 h to obtain the alkenyl epoxy co-modified two-dimensional heat conducting filler.
  5. 5. The method of claim 4, wherein the two-dimensional thermally conductive filler is a sheet-like boron nitride nanoplatelet.
  6. 6. The method of claim 1, wherein the epoxy-modified zero-dimensional heat-conducting filler is prepared by dispersing 5-15 parts of gamma-glycidoxypropyl trimethoxysilane in 100-150 parts of ethanol water, adjusting pH to 4-5, prehydrolyzing at 40-60 ℃ for 20-40min, adding 100 parts of zero-dimensional heat-conducting filler, and reacting at 70-90 ℃ for 4-8 h to obtain the epoxy-modified zero-dimensional heat-conducting filler.
  7. 7. The method of claim 6, wherein the zero-dimensional thermally conductive filler is spherical alumina.
  8. 8. The method of claim 1, wherein the mass ratio of the mercapto-modified one-dimensional heat conductive filler, the alkenyl epoxy co-modified two-dimensional heat conductive filler and the epoxy modified zero-dimensional heat conductive filler is 1 (0.7-0.9): 0.4-0.6.
  9. 9. The method of claim 1, wherein the anhydride-based curing agent is methyltetrahydrophthalic anhydride, the click reaction catalyst is triphenylphosphine, and the curing accelerator is an imidazole-based accelerator.
  10. 10. An epoxy resin casting material for a solid state transformer, characterized in that the epoxy resin casting material is prepared by the method according to any one of claims 1 to 9.

Description

Epoxy resin castable for solid-state transformer and preparation method thereof Technical Field The application relates to the technical field of polymer composite materials, in particular to an epoxy resin castable for a solid-state transformer and a preparation method thereof. Background The epoxy resin castable is a key material for insulating and packaging the solid-state transformer due to excellent insulativity, adhesiveness and manufacturability. With the continuous increase of the power density of devices, heat dissipation becomes a bottleneck restricting the reliability thereof. The conventional means for improving the heat conducting property is to fill the heat conducting filler in a high proportion, but the method generally causes the problems of broken continuity of the resin matrix, sharp increase of viscosity, difficult molding, large internal stress, remarkable reduction of mechanical strength and the like. However, for devices such as solid state transformers that experience temperature cycling over a long period (-40 ℃ to 150 ℃) the matching and stability of the coefficients of thermal expansion is a more critical reliability indicator than the mere pursuit of high thermal conductivity. The Coefficient of Thermal Expansion (CTE) of epoxy after curing is typically as high as 50-80 ppm/°c, whereas the CTE of copper conductors is only about 17 ppm/°c, with a large difference between the two. Under frequent temperature fluctuations, such CTE mismatch can create significant shear stress at the interface, leading to debonding, microcrack initiation, and even failure. Therefore, how to improve the heat conduction performance, simultaneously, effectively reduce the thermal expansion coefficient of the epoxy castable and optimize the isotropy of the epoxy castable becomes a technical problem to be solved in the field. Disclosure of Invention The application provides an epoxy resin casting material for a solid-state transformer and a preparation method thereof, wherein the epoxy resin casting material uses epoxy resin as a main material, uses a functional heat-conducting filler for optimization, and is beneficial to restraining the thermal expansion behavior of a resin matrix, so that the thermal expansion coefficient is reduced, the anisotropy is reduced, and the casting material has good thermal cycle stability. The application provides a method for preparing an epoxy resin castable for a solid-state transformer, which comprises the following steps of providing 100 parts of epoxy resin, 80-120 parts of anhydride curing agent, 150-300 parts of functionalized heat conducting filler, 0.1-0.5 part of click reaction catalyst and 0.5-2 parts of curing accelerator as raw materials, wherein the functionalized heat conducting filler comprises mercapto modified one-dimensional heat conducting filler, alkenyl epoxy co-modified two-dimensional heat conducting filler and epoxy modified zero-dimensional heat conducting filler, M2 comprises the steps of stirring and defoaming the functionalized heat conducting filler, the click reaction catalyst and the epoxy resin in vacuum at 50-60 ℃ for 10-30 min, maintaining stirring and heating to 70-80 ℃ and mixing for 10-20 min, enabling mercapto groups of the mercapto modified one-dimensional heat conducting filler and alkenyl groups on the surface of the alkenyl epoxy co-modified two-dimensional heat conducting filler to undergo click chemical reaction to obtain a premix, M3 comprises the steps of adding the anhydride curing agent and the curing accelerator into the premix, stirring and mixing under vacuum condition, pouring and removing the mixture, and obtaining the solid-state transformer winding after pouring into a solid-state transformer winding. According to the application, the casting material takes epoxy resin as a continuous phase, and a three-dimensional network is built in the composite material by introducing multi-scale heat conducting filler with specific reactive functional groups on the surfaces. The method is favorable for forming a rigid filler framework connected by covalent bonds through a stepwise construction mechanism of connecting the filler first and then fusing the matrix, and the framework can restrict the free expansion of the resin matrix under the temperature change to a certain extent, so that the thermal expansion coefficient of the composite material is reduced. Meanwhile, due to the uniform distribution characteristic of the filler framework, the thermal expansion behaviors of the composite material in three directions of X, Y, Z tend to be consistent, and the internal stress concentration caused by anisotropic expansion is reduced, so that the thermal cycle stability of the castable is improved. Specifically, in the initial stage of solidification, through the action of a click reaction catalyst, the mercapto group on the surface of the one-dimensional filler and the alkenyl group on the surface of the two-dimensional filler are subj