Strippable Cable Shield Composition Using Chlorinated Polyethylene
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Solution Overview
Problem
The strong bond between insulation and semiconductive shielding in electrical conductors makes it difficult to separate the layers, leading to time-consuming splicing and terminal connections, and can result in carbon residues on the insulation, while existing strippable materials like nitrile rubber face issues with agglomeration and property deterioration.
Innovation Solution
A strippable semiconductive shield composition using chlorinated polyethylene (CPE) with ethylene-vinyl acetate copolymer and carbon black, crosslinked through organic peroxides or silane functionality, which reduces adhesion between the insulation and shielding layers, allowing for easy stripping with a controlled strip force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a strong bond is formed between insulation and semiconductive shielding, then adhesion strength is improved, but separation difficulty increases and carbon residue is generated
Solution Approach 1:
The patent changes the chemical composition parameters of the semiconductive shield by incorporating NBR (nitrile rubber) at specific concentrations (5-50 parts by weight per 100 parts polyolefin). This compositional parameter change modifies the adhesion characteristics to achieve controlled stripability while maintaining adequate bonding during operation.
Solution Approach 2:
The patent creates a composite material system by combining polyolefin (base material) with NBR (strip control agent) and carbon black (conductive filler). This composite approach allows the semiconductive shield to exhibit both adequate adhesion for operational stability and controlled stripability for installation/maintenance, resolving the contradiction between strong bonding and easy separation.
2Ease of operation
If NBR is used as strip control agent, then stripability is improved, but agglomeration and property deterioration occur
Solution Approach 1:
The patent optimizes the concentration parameter of NBR within a specific range (5-50 parts per 100 parts polyolefin) and controls the mixing process parameters to prevent agglomeration. This parameter optimization ensures uniform dispersion of NBR, maintaining material stability while achieving the desired stripability.
Solution Approach 2:
The patent uses carbon black as an intermediary material that disperses uniformly throughout the polyolefin-NBR matrix. This intermediary filler helps distribute stress and prevents NBR agglomeration, thereby improving material stability while maintaining the strip control functionality.
3Strength
If crosslinking bonds are formed between insulation and shielding, then bond strength is improved, but splicing time increases
Solution Approach 1:
The patent creates a homogeneous composite structure where NBR is uniformly distributed throughout the polyolefin matrix. This homogeneity ensures consistent adhesion properties across the interface, providing adequate bond strength for operational reliability while allowing uniform and predictable separation during splicing operations.
Solution Approach 2:
The patent modifies the chemical composition parameters by incorporating NBR, which changes the nature of the bond from strong crosslinked bonds to controlled adhesion bonds. This parameter change reduces the energy required for separation, thereby reducing splicing time while maintaining adequate operational bond 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 composition achieves a strip force of 1.4 to 10.9 kg per 1.3 cm, facilitating efficient separation of layers without carbon residue, and is stable under heat aging, improving manufacturing efficiency and product quality.
Implementation Method 1
CPE with 20 to 100 mole percent of chlorine content provides a similar solubility parameter range as that of acrylonitrile copolymer containing 10 to 40 mole percent of acrylonitrile. As such, the polarity of acrylonitrile copolymer is matched by the polarity of CPE.
Implementation Method 2
Polymer immiscibility and decreased interfacial crosslinking between the insulation shield and polyolefin insulation substrate are key factors for decreasing adhesion between two layers in electric cable system.
Implementation Method 3
crosslinked through organic peroxides or silane functionality
Data Source
AI summary
Strippable semiconductive shields comprise a composition comprising in weight percent (wt%) based on the weight of the composition: (A) 20 to 80 % of an interpolymer of an olefin and an a,ß-unsaturated carbonyl comonomer, (B) 1 to 90 % chlorinated polyolefin, (C) 20 to 45 % carbon black, (D) 0.1 to 5 % antioxidant, (E) 0.01 to 5% acid scavenger stabilizer; (F) Optionally free radical initiator, (G) Optionally silane functionality, (H) Optionally a sulfur-containing curative, and (I) Optionally a radiation-cure catalyst.