Semiconductive Polypropylene Composition With Lower Carbon Black Loading
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Solution Overview
Problem
Existing semiconductive compositions for cables face challenges in achieving a balance between good conductivity, mechanical properties, and processability due to high amounts of conductive fillers like carbon black, which impair miscibility with polymeric components, affecting mechanical properties.
Innovation Solution
A semiconductive composition comprising a heterophasic propylene copolymer with a matrix phase and elastomeric phase, combined with a reduced amount of carbon black, ranging from 5.0 to 40.0 wt%, to enhance processability, conductivity, and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high amounts of carbon black (40-50 wt%) are used to achieve semiconductive properties, then conductivity is improved, but mechanical properties deteriorate due to poor miscibility with polymeric components
Solution Approach 1:
The patent changes the concentration parameter of carbon black from the conventional 40-50 wt% down to 5-40 wt%, achieving sufficient conductivity at lower concentrations when combined with the heterophasic propylene copolymer matrix. This parameter change resolves the contradiction by reducing the harmful amount of filler while maintaining the desired electrical properties.
Solution Approach 2:
The patent uses a composite material system consisting of heterophasic propylene copolymer matrix combined with carbon black filler. The specific composite structure with dispersed elastomeric phase within the matrix phase creates a synergistic effect that improves both conductivity and mechanical properties simultaneously, resolving the contradiction between these two properties.
2Reliability
If high amounts of carbon black are used to ensure sufficient conductivity, then electrical properties are improved, but processability deteriorates
Solution Approach 1:
The patent reduces the carbon black content parameter from 40-50 wt% to 5-40 wt%, which significantly improves processability while maintaining sufficient conductivity. The lower filler loading reduces viscosity and improves flow characteristics during processing operations.
Solution Approach 2:
The heterophasic propylene copolymer acts as an intermediary matrix that facilitates better dispersion and compatibility of carbon black particles. The elastomeric phase within the matrix serves as a mediator that enhances the interface between the polymer and filler, improving processability while maintaining conductivity.
3Reliability
If high amounts of carbon black are used to achieve semiconductive properties, then conductivity is improved, but miscibility with polymeric components deteriorates
Solution Approach 1:
The patent employs a composite material system where the heterophasic propylene copolymer matrix with its two-phase structure (crystalline matrix phase and elastomeric dispersed phase) creates a more compatible environment for carbon black dispersion. This composite structure improves miscibility and reduces aggregation of filler particles.
Solution Approach 2:
The patent creates local quality variations within the matrix through the heterophasic structure, where the elastomeric phase provides localized regions with different properties that enhance filler dispersion. This local differentiation improves overall miscibility and distribution of carbon black throughout the composition.
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 good balance of properties, including improved conductivity and mechanical strength, while reducing the amount of carbon black, thus enhancing the overall performance of semiconductive layers in medium and high voltage cables.
Implementation Method 1
a heterophasic propylene copolymer having a matrix phase and an elastomeric phase dispersed in said matrix phase
Implementation Method 2
compositions used for semiconductive layers of cables usually include a solid conductive filler such as carbon black in amounts of about 40 to 50 wt % in order to render these compositions semiconductive
Data Source
AI summary
The present invention relates to a semiconductive composition comprising (A) at least 52.0 wt %, preferably from 55.0 to 90.0 wt %, more preferably from 60.0 to 85.0 wt %, most preferably from 65.0 to 80.0 wt % of a heterophasic propylene copolymer having a matrix phase and an elastomeric phase dispersed in said matrix phase, based on the total weight amount of the semiconductive composition; and (B) from 5.0 to 40.0 wt %, preferably from 10.0 to 38.0 wt %, more preferably from 15.0 to 35.0 wt %, most preferably from 20.0 to 33.0 wt % of carbon black based on the total weight amount of the semiconductive composition, an article comprising said semiconductive composition, preferably a cable comprising an semiconductive layer comprising said semiconductive composition and the use of said semiconductive composition as inner and/or outer semiconductive layer for medium and high voltage cables.