Foamed Electrical Wire Insulation with Fine Bubbles
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Solution Overview
Problem
Conventional foamed electrical wires experience a decrease in dielectric breakdown voltage with increased foaming magnification, and they struggle to maintain partial discharge resistance while minimizing the size of electrical equipment due to the limitations of insulating layer thickness and dielectric constant.
Innovation Solution
A foamed electrical wire with a thermoplastic resin-based insulating layer having a melting point or glass transition temperature of 150°C or more, featuring an average bubble diameter of 5 µm or less, and an effective dielectric constant of 2.5 or less, combined with non-foamed skin layers for enhanced mechanical properties and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the insulating layer is increased to prevent partial discharge deterioration, then partial discharge resistance is improved, but the size of electrical equipment increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the insulating material by using resins with specifically low dielectric constants (3.0 or less, preferably 2.5 or less) and controlling foaming characteristics to achieve fine bubble structures. This allows the insulating layer to maintain high partial discharge resistance with reduced thickness, thereby preventing equipment size enlargement while improving reliability.
2Reliability
If a resin with low dielectric constant is used to reduce partial discharge deterioration, then partial discharge resistance is improved, but selection is limited when other properties (heat resistance, solvent resistance, flexibility) are considered
Solution Approach 1:
The patent employs composite material strategies by combining resins with low dielectric constants with additives and foaming agents to create insulating layers that simultaneously achieve low dielectric constant, high heat resistance, good solvent resistance, and appropriate flexibility. This composite approach allows satisfaction of multiple property requirements while maintaining partial discharge resistance.
3Volume of moving object
If foaming magnification is increased to reduce insulating layer thickness, then equipment size is reduced, but dielectric breakdown voltage decreases
Solution Approach 1:
The patent optimizes foaming parameters to achieve fine bubble diameters (0.01-5 μm, preferably 0.03-1 μm) and controls foaming magnification to maintain dielectric breakdown voltage at 80% or more of the non-foamed resin level. By precisely controlling these parameters, the insulating layer achieves reduced thickness with maintained electrical performance.
Solution Approach 2:
The patent utilizes controlled porous foam structures with specific pore size distributions to reduce the effective dielectric constant of the insulating layer while maintaining mechanical integrity and electrical breakdown strength. The fine bubble structure creates a porous material that lowers dielectric constant without compromising dielectric breakdown voltage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution maintains high dielectric breakdown voltage and improves partial discharge resistance while reducing the size of electrical equipment, achieving effective solvent and chemical resistance, and retaining mechanical strengths like tensile strength and wearing resistance.
Implementation Method 1
As a means for decreasing the substantial dielectric constant of the insulating layer, such a measure is studied as foaming the insulating layer
Implementation Method 2
foamed insulating layer having an average bubble diameter of 5 µm or less and an effective dielectric constant of 2.5 or less
Implementation Method 3
a thermoplastic resin that is a crystalline thermoplastic resin having a melting point of 150°C or more
Implementation Method 4
a non-crystalline thermoplastic resin having a glass transition temperature of 150°C or more
Data Source
Figure 1(a)~2(c)
Figure 3
AI summary
{Problems} To provide a foamed electrical wire having a fine dielectric breakdown voltage and a method of producing the foamed electrical wire. {Means to solve} The foamed insulating layer 2 contains a thermoplastic resin having heat resistant and has an average bubble diameter of 5 µm or less. It is preferable that the effective dielectric constant of the foamed insulating layer 2 is 2.5 or less, and the foamed insulating layer 2 contains preferably any of polyphenylene sulfide, polyethylene naphthalate, polyethylene telephthalate, polyether ether ketone and a thermoplastic polyimide, more preferably includes a crystalline thermoplastic resin. Furthermore, it is preferable to contain a non-foamed outer skin layer outside of the foamed insulating layer 2, or contain a non-foamed inner skin layer inside of the foamed insulating layer 2, or contain the both skin layers.