Semiconductive Layer for Power Cables Using Silane Crosslinking
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Solution Overview
Problem
High- or medium-voltage power cables using the peroxide crosslinking method face issues with decomposition products like methane and water, leading to increased risk of breakdown and explosiveness, and the processing of carbon black fillers is difficult due to premature crosslinking.
Innovation Solution
A semiconductive crosslinked layer is created using a polymer composition with epoxy functional groups, a crosslinking agent, and electrically conductive fillers with a high BET specific surface area, avoiding organic peroxides and allowing for easy processing and high mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If peroxide crosslinking is used to create semiconductive layers in power cables, then crosslinking is achieved, but decomposition products like methane and water are formed causing breakdown risks and processing difficulties
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking system by replacing peroxide-based crosslinking with silane-based crosslinking. This parameter change fundamentally alters the crosslinking chemistry to produce different by-products (acetic acid instead of methane and water), thereby resolving the harmful by-products issue while maintaining crosslinking effectiveness
Solution Approach 2:
The patent converts the potentially harmful crosslinking process into a beneficial one by using silane crosslinking where the by-products (acetic acid and water) can be effectively managed through the high surface area filler and venting design, transforming a harmful process into a controlled and beneficial crosslinking mechanism
2Reliability
If carbon black is added in substantial quantities to make the composition semiconductive, then electrical conductivity is achieved, but processing becomes difficult due to premature crosslinking and rheological issues
Solution Approach 1:
The patent changes the physical parameters of the filler by using high surface area carbon black (≥100 m²/g) instead of conventional carbon black. This parameter change improves dispersion and reduces the tendency for premature crosslinking, making processing easier while maintaining the necessary electrical conductivity for semiconductive properties
Solution Approach 2:
The patent creates a composite material system where high surface area carbon black is combined with silane crosslinking chemistry and appropriate fillers. This composite approach allows the carbon black to provide conductivity without causing processing difficulties, as the overall system composition is optimized to prevent premature crosslinking
3Loss of substance
If heat treatment is applied to accelerate methane diffusion out of the cable, then methane removal is improved, but the process becomes lengthy and expensive
Solution Approach 1:
The patent eliminates the need for lengthy heat treatment by changing the crosslinking chemistry to silane-based systems that produce acetic acid and water as by-products instead of methane. These alternative by-products are much easier to manage and remove, converting a problematic methane removal process into a simpler by-product management scenario
Solution Approach 2:
The patent changes the chemical composition parameters by using silane crosslinking agents that decompose into more manageable by-products. This parameter change in the crosslinking chemistry fundamentally alters the nature of the decomposition products, making them easier to remove without requiring extensive heat treatment
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 effectively reduces the presence of crosslinking by-products, enhances mechanical properties, and simplifies the manufacturing process by eliminating the need for restrictive venting and multistep preparations, while ensuring the electrical device's stability and safety.
Implementation Method 1
a crosslinking agent B comprising at least one reactive functional group capable of reacting with the epoxy functional group of said polymer A in order to allow the crosslinking of said polymer A
Implementation Method 2
an electrically conductive filler having a BET specific surface area of at least 100 m2/g according to ASTM standard D 6556 (2014)
Data Source
AI summary
A semi-conductive crosslinked layer produced from a polymer composition includes at least one polymer A having at least one epoxy function. A cross-linking agent B includes at least one reactive function that can react with the epoxy function of said polymer A in order to allow the cross-linking of said polymer A. The polymer composition also has an electrically conductive filler having a specific surface area BET of at least 100 m2/g according to the ASTM standard D 6556.