Crosslinkable Polyethylene Insulation for Cable Tracking Resistance
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Solution Overview
Problem
Current track-resistant polymer compositions for wires and cables suffer from low heat resistance, electrical safety issues, voltage drops, short circuits, mechanical weaknesses, and insufficient tracking resistance, particularly in high-voltage applications where they are exposed to environmental factors like dust and trees, leading to increased risk of failure and fire spread.
Innovation Solution
A crosslinkable polymer composition comprising a multimodal copolymer of ethylene and hexene with specific molecular weight distribution and crystallinity, combined with minimal carbon black content, which provides enhanced tracking resistance, heat resistance, and mechanical properties, including UV resistance, while reducing visibility and fire risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer compositions containing carbon black are used to achieve tracking resistance of 4.5 kV, then tracking resistance is improved, but heat resistance deteriorates and fire risk increases
Solution Approach 1:
The patent changes the chemical composition parameters by using specific polyethylene-polypropylene blends (50-95 wt% polyethylene, 5-50 wt% polypropylene) and controlling carbon black content (0.1-5 wt%), crystallinity (40-80%), and density (0.85-0.97 g/cm³) to achieve both high tracking resistance (≥4.5 kV) and improved heat resistance compared to traditional carbon black compositions
Solution Approach 2:
The patent creates a composite material system combining polyethylene, polypropylene, carbon black, and optional fillers (calcium carbonate, magnesium hydroxide, talc) in specific ratios to achieve synergistic effects that simultaneously improve tracking resistance, heat resistance, and mechanical properties
2Reliability
If carbon black content is increased to improve tracking resistance, then tracking resistance is improved, but visibility increases and aesthetic appearance deteriorates
Solution Approach 1:
The patent optimizes carbon black content to a specific range (0.1-5 wt%, preferably 0.5-2 wt%) to achieve the minimum effective concentration for tracking resistance while minimizing visual impact, allowing the cable to maintain better aesthetic appearance in overhead applications
3Ease of manufacture
If traditional polymer compositions are used for covered conductors, then ease of manufacture is maintained, but mechanical strength and durability deteriorate in high-voltage applications
Solution Approach 1:
The patent specifies precise parameter ranges including density (0.85-0.97 g/cm³), crystallinity (40-80%), and compositional ratios to achieve optimal mechanical strength and electrical performance while maintaining compatibility with existing extrusion and manufacturing processes
Solution Approach 2:
The patent employs composite material formulation combining polyethylene, polypropylene, and additives in specific proportions to enhance mechanical strength, UV resistance, and electrical performance without significantly complicating the manufacturing process
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 polymer composition achieves superior tracking resistance up to 6 kV, improved mechanical strength, and UV stability, reducing the risk of fire spread and power losses, making it suitable for high-end wire and cable applications, including optical cables and overhead power cables.
Implementation Method 1
The copolymer having a crystallinity, determined by DSC as described herein, of at least 40%
Data Source
AI summary
The present invention relates to a crosslinkable polymer composition comprising a copolymer of ethylene and hexene, which is a multimodal polyethylene having at least two polymer fractions present in the polymer, each having different weight average molecular weights, the copolymer having a crystallinity, determined by DSC as described herein, of at least 40%, the polymer composition further comprising a carbon black content of not more than 4 wt. %, based on the total weight of the polymer composition, wherein the polymer composition does not contain a silane-modified polymeric component, and the polymer composition passes the tracking resistance test at least at 4.5 kV for 1 h followed at 4.75 kV for 1 h, determined according to IEC60587 (2007), method 2A, on compression molded plaques prepared according to ISO 11357 The present invention further relates to a track resistant wire or cable comprising at least one layer of the above polymer composition or to the use of the polymer composition in a wire or cable for increasing track resistance, fire retardancy and/or heat resistance. The present invention further relates to a method for manufacturing the above polymer composition.