Flame-Retardant Cable Jacket Composition With Higher Tear Strength
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Solution Overview
Problem
Current flame retardant polymer compositions for high voltage cables face challenges in meeting both mechanical and flame retardant property requirements, often exhibiting inferior tensile strength, elongation at break, and tear strength, particularly in high voltage applications as specified in IEC 60840:2020.
Innovation Solution
A flame retardant polymer composition comprising specific weight percentages of copolymers of ethylene, polyethylene and polypropylene containing units, silicon fluid, magnesium hydroxide, and carbon black, optimized to provide enhanced mechanical and flame retardant properties, including a range of components such as copolymers of ethylene and alpha olefin units with defined densities and melt flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flame retardant compounds are used to achieve flame retardant properties, then flame retardancy is improved, but mechanical properties such as tensile strength and tear strength deteriorate
Solution Approach 1:
The patent employs a composite polymer system combining polyethylene base resin with multiple copolymer additives (ethylene-methyl acrylate, ethylene-methyl methacrylate, ethylene-alpha olefin) to create a flame retardant composition that achieves both flame retardancy and mechanical strength. The synergistic interaction between different polymer components allows simultaneous improvement of both properties rather than the traditional trade-off.
Solution Approach 2:
The patent specifies precise compositional parameters including weight percentages of each component (polyethylene base resin: 70-85 wt%, copolymers: 5-20 wt% each, magnesium hydroxide: 3-10 wt%), density ranges (860-910 kg/m³), and melt flow rates (0.1-5.0 g/10min) to optimize the balance between flame retardant performance and mechanical properties. By controlling these parameters within specific ranges, the composition achieves both required flame retardancy and mechanical strength.
2Reliability
If flame retardant materials are used to achieve flame retardant properties, then flame retardancy is improved, but elongation at break deteriorates
Solution Approach 1:
The multi-component polymer composite system maintains elongation at break above 300% by incorporating flexible copolymer components (ethylene-methyl acrylate and ethylene-methyl methacrylate) that provide both flame retardancy through char formation and maintain ductility through their elastomeric properties. The composite structure allows simultaneous achievement of flame retardancy and elongation requirements.
Solution Approach 2:
The patent specifies that the composition must achieve elongation at break of 300% or more while maintaining flame retardant properties. This is accomplished by controlling the molecular weight, density (860-910 kg/m³), and melt flow rate (0.1-5.0 g/10min) parameters of the copolymer components to ensure adequate chain flexibility and elongation capability despite the presence of flame retardant additives.
3Reliability
If flame retardant materials are used to achieve flame retardant properties, then flame retardancy is improved, but tear strength deteriorates
Solution Approach 1:
The patent uses a composite system where polyethylene base resin provides structural integrity and tear resistance, while copolymer additives (ethylene-methyl acrylate, ethylene-methyl methacrylate) provide flame retardancy. The synergistic combination ensures tear strength exceeds 8.0 N/mm while maintaining flame retardant performance, resolving the traditional trade-off between these properties.
Solution Approach 2:
By controlling the molecular weight distribution, density (860-910 kg/m³), and melt flow rate (0.1-5.0 g/10min) of the copolymer components, the patent optimizes the balance between tear strength and flame retardancy. The specific parameter ranges ensure adequate molecular entanglement for tear resistance while maintaining flame retardant char formation capability.
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 improved tensile strength, elongation at break, and tear strength, while maintaining effective flame retardancy, meeting the stringent requirements of high voltage cable jackets as described in IEC 60840:2020, with enhanced mechanical properties and reduced risk of cracking.
Implementation Method 1
The composition comprises 40.0 to 55.0 wt% of a magnesium hydroxide
Implementation Method 2
maintaining effective flame retardancy
Implementation Method 3
The cracking properties of a material can be understood by measurements of tear strength at different temperatures
Implementation Method 4
0.1 to 3.0 wt% of a silicon fluid and/or silicone gum
Data Source
AI summary
The present invention relates to a flame retardant polymer composition comprising (A) 2.0 to 15.0 wt% of a copolymer of ethylene comprising units selected from the group consisting of methyl acrylate, methyl methacrylate or mixtures thereof; (B) 0 to 4.0 wt% of a polyethylene and/or polypropylene containing units originating from maleic acid anhydride; (C) 0.1 to 3.0 wt% of a silicon fluid and/or silicone gum; (D) 40.0 to 55.0 wt% of a magnesium hydroxide; (E) 2.0 to 15.0 wt% of a copolymer of ethylene and alpha olefin comonomer units having from 4 to 10 carbon atoms, which has a density of from 860 to 910 kg/m3, determined according to ISO 1183; (F) 18.0 to 35.0 wt% of a copolymer of ethylene and alpha olefin comonomer units having from 4 to 10 carbon atoms, which has a density of from 920 to 960 kg/m3, determined according to ISO 1183, and a melt flow rate MFRs of from 0.05 to 2.50 g/10 min, determined according to ISO 1133 at a temperature of 190°C and a load of 5.0 kg; and (G) 0 to 8.0 wt% of carbon black, wherein all weight percentages are based on the total weight of the flame retardant polymer composition; an article, such as a wire or cable, comprising said flame retardant polymer composition; and the use of said flame retardant polymer composition for the production of an article, such as a wire or cable.