CN-122011445-A - Polyimide-epoxy resin composite material for high-frequency insulation and preparation method and application thereof

Abstract

The invention discloses a polyimide-epoxy resin composite material for high-frequency insulation and a preparation method and application thereof, belonging to the technical field of high-frequency power equipment insulation materials. The preparation method comprises the steps of carrying out surface carboxylation treatment on a polyimide film to obtain a surface carboxylation film, immersing the surface carboxylation film into silane coupling agent hydrolysis liquid to carry out surface modification to obtain a surface silanization film, wherein the silane coupling agent hydrolysis liquid comprises an amino-containing silane coupling agent, a solvent, acetic acid and bivalent tin salt, and casting and curing an epoxy resin composition on the surface of the surface silanization film to obtain the polyimide film. According to the invention, a chemical bridging interface is constructed on the polyimide surface by means of a synergistic catalytic system formed by acetic acid and stannous salt through silane coupling agent treatment, so that the insulating property, interface bonding strength and electrothermal aging resistant life of the composite material under high frequency are remarkably improved.

Inventors

• ZHANG LI
• YANG GE
• WANG GUAN
• WANG HUI
• Gao Tianqu
• Rachmanov Ekromrong Usmonovic
• Kurbovov Nurbek Nurulo Ugly

Assignees

• 山东大学
• 塔什干国立技术大学

Dates

Publication Date

20260512

Application Date

20260414

Claims (10)

1. 1. The preparation method of the polyimide-epoxy resin composite material for high-frequency insulation is characterized by comprising the following steps of: s1, carrying out surface carboxylation treatment on a polyimide film to obtain a surface carboxylated film; S2, immersing the surface carboxylated film into silane coupling agent hydrolysate for surface modification to obtain a surface silanized film, wherein the silane coupling agent hydrolysate comprises an amino-containing silane coupling agent, a solvent, acetic acid and stannous salt; and S3, pouring an epoxy resin composition on the surface of the surface silanized film, and curing to obtain the polyimide-epoxy resin composite material for high-frequency insulation.
2. 2. The method according to claim 1, wherein the surface carboxylation treatment comprises treating the polyimide film in an alkaline solution and then in an acid solution.
3. 3. The preparation method according to claim 2, wherein the alkaline solution is a sodium hydroxide solution with a concentration of 1.0-5.0 mol/L, the treatment is carried out in the alkaline solution at 50-70 ℃ for 30-60 min, the acid solution is a hydrochloric acid, sulfuric acid or acetic acid solution with a concentration of 0.5-1.5 mol/L, and the treatment is carried out in the acid solution for 20-40 min.
4. 4. The preparation method of claim 1, wherein in step S2, the immersion time in the hydrolysate of the silane coupling agent is 4-10 min.
5. 5. The preparation method of the silane coupling agent hydrolysate, which is characterized in that the preparation method comprises the steps of uniformly mixing stannous salt and the amino-containing silane coupling agent in a solvent, adding acetic acid to adjust the pH to 3-5, and hydrolyzing for 15-60 min.
6. 6. The method according to claim 1, wherein the amino-containing silane coupling agent is at least one selected from the group consisting of 3-aminopropyl triethoxysilane, γ -aminopropyl trimethoxysilane, and N- (β -aminoethyl) - γ -aminopropyl trimethoxysilane, and the solvent is a mixed solvent of ethanol and water.
7. 7. The method according to claim 1, wherein the concentration of the amino group-containing silane coupling agent in the silane coupling agent hydrolysate is 1 to 5wt%, and the concentration of the stannous salt is 0.05 to 0.5wt%.
8. 8. The preparation method of claim 1, wherein the epoxy resin composition comprises 100 mass percent (80-90) of epoxy resin, 0.8-1.2 of curing agent and accelerator.
9. 9. A polyimide-epoxy resin composite material for high-frequency insulation, characterized by being prepared by the preparation method of any one of claims 1 to 8.
10. 10. The use of a polyimide-epoxy resin composite material for high frequency insulation according to claim 9, for the preparation of an insulating member for high frequency power electronics.

Description

Polyimide-epoxy resin composite material for high-frequency insulation and preparation method and application thereof Technical Field The invention relates to the technical field of high-frequency power equipment insulating materials, in particular to a polyimide-epoxy resin composite material for high-frequency insulation, and a preparation method and application thereof. Background The information disclosed in the background of the invention is only for enhancement of understanding of the general background of the invention and is not necessarily to be taken as an admission or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art. For power electronic devices operating under high frequency conditions (typically 1kHz and above), particularly high frequency transformers with operating frequencies exceeding 10kHz, composite insulation systems consisting of Epoxy (EP) integrally cast and Polyimide (PI) film wrapped are commonly employed for achieving high power density and efficient power conversion. However, polyimide and epoxy have inherent differences in molecular structure, surface energy and thermodynamic properties, which are typical thermodynamically incompatible systems. When the two are directly compounded, the interfaces are combined mainly by virtue of physical actions such as Van der Waals force and the like, so that a weak boundary layer with low cohesive strength and unstable structure is formed. Under the long-term coupling action of multiple stresses such as high frequency, high voltage, high temperature and the like, the physical bonding interface is extremely easy to generate microscopic defects and interface debonding due to mismatch of expansion coefficients of materials, and a micron-sized air gap is formed. These interface defects can cause severe distortion of the electric field, which becomes a starting point for space charge accumulation and partial discharge. The continuous erosion of partial discharge can further accelerate the degradation of interface materials to form vicious circle, and finally, the growth of electricity branches and early insulation breakdown are induced, so that the running reliability and the service life of equipment are severely restricted. In order to improve the interface performance of polyimide-epoxy resins, the prior art has mainly started from two directions, namely, modification of a single matrix material, such as doping nano-filler into polyimide or epoxy resin to improve the dielectric or heat-resistant performance of the matrix, and physical or simple chemical treatment of the interface, such as plasma cleaning to improve the surface energy or coating of transition coating to improve the compatibility. However, the former is often unable to fundamentally solve the problem of interfacial chemical bonding deficiency, while the latter generally has the limitations of unstable treatment effect, complex process or introduction of new interfacial defects. In addition, the existing method is difficult to construct a high-strength chemical bonding connection between polyimide and epoxy resin, which can still keep stable for a long time under high-frequency dynamic electric stress. Therefore, how to establish a stable and durable chemical bonding interface between polyimide and epoxy resin two phases so as to effectively inhibit interface discharge and insulation aging under high-frequency severe working conditions has become a key technical bottleneck for improving the composite insulation reliability of high-frequency power equipment. Disclosure of Invention In view of the above, the invention provides a polyimide-epoxy resin composite material for high-frequency insulation, and a preparation method and application thereof. According to the invention, a chemical bridging interface is constructed on the polyimide surface by means of a synergistic catalytic system formed by acetic acid and stannous salt through silane coupling agent treatment, so that the insulating property, interface bonding strength and electrothermal aging resistant life of the composite material under high frequency are remarkably improved. In a first aspect, the invention provides a preparation method of a polyimide-epoxy resin composite material for high-frequency insulation, which comprises the following steps: s1, carrying out surface carboxylation treatment on a polyimide film to obtain a surface carboxylated film; S2, immersing the surface carboxylated film into silane coupling agent hydrolysate for surface modification to obtain a surface silanized film, wherein the silane coupling agent hydrolysate comprises an amino-containing silane coupling agent, a solvent, acetic acid and stannous salt; and S3, pouring an epoxy resin composition on the surface of the surface silanized film, and curing to obtain the polyimide-epoxy resin composite material for high-frequency insulation. Preferably, the surface carboxylation