Flame Retardant Polymer Composition for Wire and Cable
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Solution Overview
Problem
Existing flame retardant polymer compositions for wires and cables face challenges in achieving a balance between good flame retardancy and mechanical properties, particularly tensile strength, tear resistance, and high-temperature pressure resistance, while also avoiding the use of costly inorganic fillers and hazardous gases.
Innovation Solution
A flame retardant polymer composition comprising an ethylene copolymer with polar comonomer units, a silicone-group containing compound, and an inorganic filler, with the addition of an ethylene homo- or copolymer to enhance melting enthalpy and mechanical properties, specifically including 20-45 wt% inorganic filler and 15 wt% or more ethylene homo- or copolymer with a density of 940-960 kg/m³, resulting in improved tensile properties and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic fillers such as Al(OH)3 and Mg(OH)2 are included in large amounts (50 to 60 wt.%) to improve flame retardancy, then flame retardant properties are improved, but mechanical properties and processability deteriorate
Solution Approach 1:
The patent changes the parameter of inorganic filler content from the conventional high range (50-60 wt.%) to a reduced range (20-40 wt.%), thereby maintaining flame retardancy while improving mechanical properties and processability. This parameter optimization resolves the contradiction by finding a balanced content level that satisfies both requirements.
Solution Approach 2:
The patent creates a composite polymer composition combining multiple polymer components (polyethylene, polypropylene, elastomer) with inorganic fillers and flame retardant compounds. This composite structure allows the different materials to complement each other, providing both flame retardancy and good mechanical properties without relying on excessive filler content.
2Reliability
If inorganic fillers are included in large amounts to improve flame retardancy, then flame retardant properties are improved, but processability deteriorates
Solution Approach 1:
The patent reduces the inorganic filler content parameter from 50-60 wt.% to 20-40 wt.%, which directly improves processability while maintaining adequate flame retardancy. This parameter change eliminates the processing difficulties associated with high filler loads.
Solution Approach 2:
The patent introduces a specific elastomer component with Shore A 40-80 hardness to improve the local quality of the composition's processability. The elastomer acts as a lubricant and processing aid, enabling good processability even with inorganic fillers present, while the flame retardant compounds provide the necessary fire resistance.
3Reliability
If halide-containing compounds are included to improve flame retardancy, then flame retardant properties are improved, but hazardous and corrosive gases are liberated during burning
Solution Approach 1:
The patent replaces halide-containing flame retardants with inorganic fillers like Al(OH)3 and Mg(OH)2 that decompose endothermically to release water vapor instead of toxic halogen gases. This substitution converts the harmful effect of halogen gas release into a beneficial effect where water vapor acts as an inert diluent, suppressing combustion without creating toxic byproducts.
Solution Approach 2:
The patent uses inorganic fillers that decompose and are consumed during the flame retardant process, releasing harmless water vapor. These fillers act as sacrificial materials that protect the polymer matrix from burning, sacrificing themselves in the process but leaving no toxic residue, unlike persistent halogenated flame retardants.
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 melting enthalpy of at least 78 J/g, improved tensile strength, tear resistance, and passes the single wire burning test according to IEC 332-1, while maintaining good flame retardancy and mechanical properties without halogen- or phosphorous-containing compounds.
Implementation Method 1
flame retardant compositions include relatively large amounts, typically 50 to 60 wt.%, of inorganic fillers such as e.g. hydrated and hydroxy compounds, which during burning decompose endothermically and liberate inert gases at temperatures in the range of 200 to 600 °C
Implementation Method 2
the melting enthalpy of the polymer composition has an amount of at least 78 J/g
Data Source
AI summary
A flame retardant polymer composition comprising (A) an ethylene copolymer comprising polar comonomer units, (B) a silicone-group containing compound, (C) an inorganic filler material, and (D) an ethylene homopolymer or a copolymer of ethylene with one or more other alpha-olefin comonomer units, wherein the polymer composition has a melting enthalpy of at least 78 J/g, an article, in particular a wire or cable, comprising said composition and the use of an ethylene homo- or copolymer in a flame retardant layer of a wire or cable for improving the mechanical properties of the wire or cable.