Semiconductive Polymer Composition Shear Stability

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Solution Overview

Problem

The production of power cables with semiconductive layers faces instability in conductivity due to shear forces during extrusion, limiting efficiency and requiring high carbon black loads, which compromises processability and surface smoothness.

Innovation Solution

Incorporating 4,4'-bis(1,1'-dimethylbenzyl)diphenylamine into a semiconductive polymer composition with LDPE and carbon black, allowing for reduced carbon black content while maintaining or improving conductivity stability, even under shear forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbon black loading is increased to compensate conductivity loss during extrusion, then conductivity stability is improved, but processability and surface smoothness deteriorate

Engineering Contradiction:

Improveconductivity stabilityVSAvoidprocessability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the chemical composition parameter by introducing a specific diphenyl amine compound (4,4'-bis(1,1'-dimethylbenzyl)diphenylamine) as an antioxidant. This chemical parameter change stabilizes the carbon black network structure during extrusion, maintaining conductivity without requiring increased carbon black loading, thus preserving processability and surface quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The diphenyl amine compound acts as an intermediary substance that protects the carbon black percolating network from shear-induced destruction. It mediates between the mechanical stress of extrusion and the conductive network, preventing conductivity loss without needing to increase carbon black content

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If carbon black loading is increased to compensate conductivity loss during extrusion, then conductivity stability is improved, but surface smoothness deteriorates

Engineering Contradiction:

Improveconductivity stabilityVSAvoidsurface smoothness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

By changing the chemical composition to include the specific diphenyl amine compound, the patent maintains conductivity stability at lower carbon black loadings, which in turn preserves surface smoothness. The chemical additive modifies the rheological and structural parameters of the compound during extrusion

Inventive Principle:

Principle #35Parameter changes

3Reliability

If extrusion speed is restricted to maintain conductivity stability, then conductivity stability is preserved, but productivity decreases

Engineering Contradiction:

Improveconductivity stabilityVSAvoidproduction efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The introduction of the diphenyl amine compound changes the chemical and structural parameters of the semiconductive composition, making it resistant to shear-induced conductivity loss. This allows the extrusion process to operate at higher speeds without compromising conductivity stability, thereby increasing productivity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2628162B9Semiconductive polymer composition

Publication Date: 2020.10.14 BOREALIS AG

AI summary

The invention relates to a crosslinkable semiconductive polymer composition comprising (a) a polyolefin, carbon black and a compound (b), to a cable, preferably to a crosslinkable comprising the polymer composition, to a production thereof, and preferably to a crosslinked cable comprising the polymer composition of the invention.