Polyimide Coating Composition for Low-Dielectric Wire Insulation
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Solution Overview
Problem
Polyimide coatings for conductors face challenges in balancing low dielectric constant, high heat resistance, adhesion, and flexibility, particularly in preventing corona discharge and dielectric breakdown in high-voltage electrical devices.
Innovation Solution
A polyimide coating material with a specific composition including a dianhydride monomer and diamine monomer components, optimized to achieve a dielectric constant below 3.6 and a breakdown voltage of 230 kV/mm or more, while maintaining flexibility and adhesion through the use of specific diamine and dianhydride structures and silane compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyimide resin with rigid structure is used to achieve low dielectric constant and heat resistance, then dielectric properties and heat resistance are improved, but flexibility and tensile elongation deteriorate
Solution Approach 1:
The patent uses a composite diamine structure combining rigid aromatic rings (for low dielectric constant) and flexible aliphatic chains (for flexibility). Specifically, it employs a diamine containing both aromatic rings and flexible groups such as -CH2- or -O- bonds, creating a composite molecular structure that integrates both rigid and flexible characteristics to resolve the contradiction between dielectric properties and flexibility.
Solution Approach 2:
The patent modifies the molecular structure parameters of the diamine component by introducing flexible groups (such as -CH2- chains or -O- bonds) into the aromatic ring structure. This parameter change allows the polymer chain to have greater freedom of movement while maintaining the aromatic rings necessary for low dielectric constant, thus improving flexibility without sacrificing dielectric properties.
2Ease of operation
If flexible diamines are used to improve flexibility, then flexibility and adhesion are improved, but heat resistance deteriorates
Solution Approach 1:
The patent employs a composite diamine structure that integrates rigid aromatic rings (providing heat resistance) with flexible aliphatic chains or ether groups (providing flexibility). This composite structure allows the material to simultaneously achieve high flexibility for adhesion and processing, while maintaining the thermal stability provided by the aromatic ring systems.
Solution Approach 2:
The patent applies local quality by positioning rigid aromatic rings at specific locations in the polymer chain to maintain heat resistance, while introducing flexible groups at other locations to provide flexibility. The diamine structure contains aromatic rings connected via flexible linkages, creating localized rigid and flexible regions that collectively provide both heat resistance and flexibility.
3Reliability
If low dielectric constant is achieved through rigid polyimide structure, then corona discharge resistance is improved, but coating damage during processing increases
Solution Approach 1:
The patent uses a composite diamine structure combining rigid aromatic rings (for corona discharge resistance through low dielectric constant) with flexible aliphatic chains or ether groups (for coating integrity during processing). This composite molecular architecture allows the coating to resist corona discharge while maintaining sufficient flexibility to withstand mechanical deformation during coil winding and insertion processes without cracking or damage.
Data Source
AI summary
The present invention provides: a polyimide coating material, which has low dielectric properties and improved adhesion between a conductor and the coating material and flexibility of the coating material while simultaneously preventing dielectric breakdown and partial discharge; and a coated electric wire.