Corona-Resistant Insulated Wire With Interlayer Adhesion Control
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Solution Overview
Problem
Existing insulated wires face challenges with corona resistance and breakdown voltage due to the decomposition and bubble generation of thermoplastic polyimide (TPI) during the extrusion process, leading to insulation aging and short-circuit phenomena.
Innovation Solution
The insulated wire is designed with a conductor coated sequentially with an intermediate layer of polyamide-imide and polyimide, and an insulating layer of thermoplastic polyimide (TPI) with corona-resistant materials, such as titanium dioxide, silicon dioxide, or aluminum oxide, where the mass percentage of corona-resistant materials is 6%-10% and the thickness ratio of the intermediate layer to the insulating layer is 1:(13-18).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic nanomaterials are added to improve corona resistance, then corona resistance is improved, but adhesion of the insulating layer is significantly reduced
Solution Approach 1:
The patent introduces an intermediate layer comprising polyamide-imide and polyimide between the conductor and the insulating layer containing corona-resistant materials. This intermediate layer acts as a mediator that maintains adhesion while allowing the insulating layer to provide corona resistance. The intermediate layer prevents direct contact between the insulating layer and conductor, thereby preventing adhesion loss while maintaining the corona-resistant properties of the insulating layer.
Solution Approach 2:
The patent creates a composite structure with multiple layers: an intermediate layer made of polyamide-imide and polyimide, and an insulating layer made of thermoplastic polyimide with corona-resistant materials. This composite material approach allows each layer to perform its specific function - the intermediate layer provides adhesion and the insulating layer provides corona resistance - thereby resolving the contradiction between adhesion and corona resistance.
2Reliability
If thermoplastic polyimide (TPI) is used as insulating layer material, then insulating properties are good, but decomposition and bubble generation during extrusion reduce breakdown voltage
Solution Approach 1:
The intermediate layer serves as a protective barrier between the conductor and the TPI insulating layer. It prevents direct thermal contact during the extrusion process, reducing heat transfer to the TPI material and thereby minimizing decomposition and bubble generation. This allows the TPI insulating layer to maintain its excellent insulating properties while improving breakdown voltage by preventing thermal degradation during manufacturing.
Solution Approach 2:
The intermediate layer provides beforehand cushioning against thermal damage during the extrusion process. By placing this protective layer in advance, the patent prevents the TPI material from undergoing excessive thermal stress that would cause decomposition and bubble formation, thereby preserving the breakdown voltage and insulating properties of the final product.
Data Source
AI summary
The present disclosure discloses an insulated wire and a preparation method thereof, a coil, and an electronic/electrical equipment, relating to the technical field of wire and cable production. The insulated wire includes a conductor, with an intermediate layer and an insulating layer sequentially coated on the conductor; the intermediate layer includes polyamide-imide and polyimide; and the insulating layer includes a specific proportion of TPI and corona-resistant material. By optimizing the composition of the intermediate layer and the insulating layer, the insulating layer of the present disclosure not only has good corona resistance performance but also possesses high adhesion strength, thus reducing the likelihood of breakdown in the insulated wire.