Strippable Semiconducting Composition for Polyolefin Insulation
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Solution Overview
Problem
Existing semiconducting compositions for insulated electrical conductors face challenges in balancing strippability from and adhesion to crosslinked polyolefin insulation layers, particularly in the absence of certain materials like NBR, EPBR, phenol, quinone, thiazole, thiuram sulfide, and hydrocarbon wax.
Innovation Solution
A curable semiconducting composition comprising a crosslinkable ethylene-carboxylic ester copolymer, electrically conductive fillers, and a combination of amide wax and silicone oil as strippability additives, which enhances strippability while maintaining sufficient adhesion to the crosslinked polyolefin insulation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If enough strippability additive is included in the composition of the outer semiconducting layer, then strippability is improved, but adhesion to the crosslinked polyolefin insulation layer deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the strippability additives by specifying precise compositional ranges for the polyolefin resin (85-95 wt%), first strippability additive (0.5-10 wt%), and second strippability additive (0.5-10 wt%). This parameter optimization enables the composition to achieve both adequate adhesion during installation and easy strippability during splicing operations
Solution Approach 2:
The patent creates a composite semiconducting layer composition by combining polyolefin resin with two different types of strippability additives (first and second strippability additives). This composite formulation synergistically balances adhesion and strippability properties, resolving the contradiction between these two opposing requirements
2Ease of operation
If strippability additives are included to enable clean stripping, then strippability is improved, but residue left on the insulation layer increases
Solution Approach 1:
The patent optimizes the concentration parameters of strippability additives within specific ranges (0.5-10 wt% for each additive) to achieve complete stripping without residue. The controlled parameter ranges prevent excessive additive content that would cause residue while ensuring sufficient strippability
Solution Approach 2:
The semiconducting layer is designed as a temporary component that is intentionally made easily removable. The composition uses strippability additives to enable the layer to serve its function during installation and then be completely removed during splicing, leaving no harmful residue on the insulation layer
3Strength
If adhesion promoters are included to ensure adequate adhesion, then adhesion is improved, but strippability deteriorates
Solution Approach 1:
The patent carefully controls the polyolefin resin content at 85-95 wt% and limits strippability additives to 0.5-10 wt% each, creating an optimal balance where adhesion is sufficient for installation but strippability is maintained for future removal. This parameter precision resolves the contradiction between adhesion and strippability
Solution Approach 2:
The semiconducting layer composition is formulated with specific local properties: the polyolefin resin provides base adhesion, while the strippability additives create localized zones that facilitate controlled removal. This spatial and compositional differentiation enables both strong initial adhesion and easy subsequent stripping
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 enhanced strippability with reduced force required for removal from the crosslinked polyolefin insulation layer while maintaining adequate adhesion, as demonstrated by the Strip Force Test Method.
Implementation Method 1
a peroxide-curable semiconducting composition comprising 50 to 78 weight percent (wt %) of (A) a crosslinkable ethylene-vinyl acetate copolymer, having a vinyl acetate monomeric unit content of from 25 to 40 wt %; 20 to 48 wt % of (B) carbon black; 0.1 to 2.5 wt % of (C) an amide wax; 0.1 to 2.5 wt % of (D) a silicone oil; wherein the sum of wt % (C)+wt % (D) is from 1.0 to 5.0 wt %; 0.1 to 1.5 wt % of (E) an antioxidant; and 0.1 to 1.5 wt % of (F) an organic peroxide
Data Source
AI summary
A rubberless, strippable, semiconducting composition that includes an ethylene-(carboxylic ester) copolymer having a low comonomeric unit content, carbon black, and a strippability additive combination comprising an amide wax and a silicone oil. Also provided are a cured product made from the composition, methods of making and using same, and articles containing same.