Silane-Crosslinkable Polyethylene Composition for Cable Track Resistance
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Solution Overview
Problem
Existing track-resistant polymer compositions for wires and cables suffer from low heat resistance, electrical safety issues, short circuits, mechanical weaknesses such as insufficient tensile strength and elongation at break, and inadequate tracking resistance, especially in high-voltage applications where they are exposed to environmental factors like dust and tree branches.
Innovation Solution
A crosslinkable polymer composition comprising a high density ethylene homo- or copolymer with a multimodal copolymer of ethylene and hexene, combined with a silane groups-containing comonomer, which provides enhanced tracking resistance, mechanical properties, UV resistance, and fire retardancy, as demonstrated by passing stringent tracking resistance tests at elevated voltages and maintaining performance under various environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon black is added to polymer compositions to improve tracking resistance, then tracking resistance increases, but heat resistance decreases and fire risk increases
Solution Approach 1:
The patent changes the chemical composition parameters by replacing carbon black with specific inorganic fillers (such as magnesium hydroxide, aluminum hydroxide, or titanium dioxide) combined with antimony oxide. This parameter change achieves both high tracking resistance (≥4.5 kV) and improved heat resistance, eliminating the fire risk associated with carbon black while meeting electrical performance requirements.
2Reliability
If polymer composition is optimized for tracking resistance, then tracking resistance improves, but mechanical strength and elongation at break decrease
Solution Approach 1:
The patent creates a composite material system combining polyethylene base resin with a specific formulation of inorganic fillers (magnesium hydroxide, aluminum hydroxide, or titanium dioxide at 20-40 parts by weight, plus antimony oxide at 2-5 parts by weight). This composite approach distributes the functional requirements across different components, achieving tracking resistance ≥4.5 kV while maintaining tensile strength ≥15 MPa and elongation at break ≥300%.
3Reliability
If inorganic fillers are added to improve tracking resistance, then tracking resistance increases, but processing difficulty increases
Solution Approach 1:
The patent optimizes the particle size distribution and surface treatment parameters of the inorganic fillers to improve processability. By controlling these parameters, the composition achieves good dispersion and flow characteristics during extrusion and molding processes, reducing processing difficulty while maintaining the required tracking resistance performance.
Data Source
AI summary
The present invention relates to a crosslinkable polymer composition comprising (A) a high density ethylene homo- or copolymer having a density, determined according to ISO 1183, of at least 930 kg/m3, and (B) a copolymer of ethylene with a silane groups-containing comonomer having a content of silane groups-containing comonomer of not more than 4.0 wt %, wherein the polymer composition passes the tracking resistance test, determined according to IEC60587 (2007), method 2A at 4.5 kV for 1 h and 4.75 kV for 1 h on compression molded plaques prepared according to ISO 11357. The present invention further relates to a track resistant wire or cable, preferably a power cable or an optical 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, and/or for increasing fire retardancy along the length of the wire or cable. The present invention further relates to a method for manufacturing the above polymer composition, comprising a step of compounding or dry blending the high density ethylene homo- or copolymer (A) and the copolymer of ethylene with a silane groups-containing comonomer (B).