Semiconductive Cable Insulation Elastomer Composition
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Solution Overview
Problem
The existing semiconductive layers in electrical power cable connectors require high levels of conductive carbon black to achieve desired volume resistivity, which compromises the flexibility of the material, leading to stiffness and reduced tear strength, while alternative materials like silicone rubber are costly and have lower tear strength compared to polyolefin-based compounds.
Innovation Solution
A semiconductive composition comprising 1 to 40 wt% conductive carbon black, 10 to 80 wt% of a non-olefin elastomer such as silicone or urethane rubber, and 10 to 80 wt% of an olefin elastomer, along with optional additives, to achieve a volume resistivity of less than 1000 ohm-cm, maintaining flexibility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of conductive carbon black (>30 wt%) are used to achieve desired volume resistivity, then the electrical conductivity is improved, but the flexibility and tear strength of the material deteriorate
Solution Approach 1:
The patent uses a composite elastomeric system combining polyolefin rubber (providing flexibility and tear strength) with non-polyolefin rubber (providing compatibility and processability) to create a semiconductive compound that maintains mechanical properties while achieving desired conductivity with reduced carbon black content
Solution Approach 2:
The patent changes the chemical composition parameters of the elastomeric base by specifying precise weight percent ranges of different rubber types (5-50% polyolefin, 50-95% non-polyolefin) to optimize the balance between conductivity, flexibility, and tear strength
2Reliability
If high levels of conductive carbon black (>30 wt%) are used to achieve desired volume resistivity, then the electrical conductivity is improved, but the tear strength of the material deteriorates
Solution Approach 1:
The patent creates a composite elastomeric system where polyolefin rubber provides superior tear strength while non-polyolefin rubber ensures compatibility and processability, allowing the material to maintain high tear strength even with reduced carbon black content
Solution Approach 2:
The patent optimizes the elastomeric composition parameters (5-50% polyolefin, 50-95% non-polyolefin) to achieve the desired balance between tear strength and electrical conductivity
3Ease of operation
If non-polyolefin based resins like silicone rubber are used for the semiconductive compound, then the flexibility is improved, but the cost increases significantly and tear strength decreases
Solution Approach 1:
The patent uses cost-effective polyolefin and non-polyolefin rubbers instead of expensive silicone rubber, achieving the desired flexibility and electrical properties through optimized composition rather than relying on costly materials
Solution Approach 2:
The patent creates a composite system combining different rubber types to achieve flexibility comparable to silicone rubber but at lower cost, while maintaining superior tear strength
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 achieves a balance of low volume resistivity and improved flexibility and tear strength, with stable volume resistivity over time, using a combination of non-olefin and olefin elastomers with reduced carbon black content, addressing the stiffness and cost issues of previous materials.
Implementation Method 1
the conductive filler provides a volume resistivity of less than 1000 ohm-cm
Data Source
AI summary
A molded or extruded article, e.g., an electrical part or shielded cable, comprises at least one insulation layer and at least one semiconductive layer, the semiconductive layer thick and comprising in weight percent: A. 1 to 30 wt% of conductive filler; B. 10 to 90 wt% of a non-olefin elastomer; C. 10 to 90 wt% of an olefin elastomer; and D. Optionally, 0.5 to 2.5 wt% of peroxide. Carbon black and/or metal particulates or powder typically comprise the filler, silicone or urethane rubber the non-olefin elastomer, and EPR or EPDM the olefin elastomer.