Halogen-Free Polyamide-Grated Thermoplastic Flame Retardance
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Solution Overview
Problem
Existing flame-retarded thermoplastic compositions for electrical applications face challenges in achieving high mechanical and thermomechanical properties while maintaining flame propagation resistance and thermal stability, often at the expense of ductility and with issues of exudation and inadequate thermal stability.
Innovation Solution
Development of flexible thermoplastic compositions based on polyamide-grafted functionalized polyolefins, incorporating ammonium polyphosphates and zeolites, with specific ratios and types of polyolefin backbones and polyamide grafts, to achieve high thermomechanical strength and flame retardance without halogen compounds or phosphorus plasticizers, ensuring compatibility with processing methods like extrusion and injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halogenated additives are used to achieve flame retardance, then flame propagation resistance is improved, but ecotoxicology and toxicology performance deteriorates due to toxic and corrosive vapors emitted during fires
Solution Approach 1:
The patent changes the chemical composition parameters by using halogen-free flame retardants (ammonium polyphosphates) instead of halogenated additives, and controls the phosphorus content to be less than 10% by weight to achieve both flame retardance and reduced toxicity
Solution Approach 2:
The patent creates a composite material system combining polyamide-grafted functionalized polyolefins with halogen-free flame retardants (ammonium polyphosphates) and zinc oxide, achieving flame retardance through composite action without the harmful effects of halogenated compounds
2Reliability
If flame retardants are added to achieve V0 classification, then flame propagation resistance is improved, but mechanical properties and ductility deteriorate with considerable loss in elongation at break
Solution Approach 1:
The patent optimizes the phosphorus content parameter to be less than 10% by weight, which is lower than conventional formulations, thereby achieving flame retardance while preserving mechanical properties and ductility
Solution Approach 2:
The patent uses polyamide-grafted functionalized polyolefins where the grafted polyamide units provide localized flame retardance at the molecular level, allowing the bulk material to maintain its mechanical properties
3Reliability
If conventional flame-retarded compositions are used, then flame propagation resistance is achieved, but thermal stability is inadequate with loss of mechanical properties after thermal aging
Solution Approach 1:
The patent creates a stable composite system combining polyamide-grafted functionalized polyolefins with ammonium polyphosphates and zinc oxide, where the components work synergistically to provide both flame retardance and thermal stability, retaining 70% of initial mechanical properties after thermal aging
Solution Approach 2:
The patent uses ammonium polyphosphates which decompose in a controlled manner during combustion to form protective phosphoric acid layers, providing flame retardance through a sacrificial mechanism that does not compromise long-term thermal stability
4Ease of operation
If phosphorus plasticizers are used to maintain flexibility, then ductility is improved, but exudation occurs and phosphorus content increases above acceptable levels
Solution Approach 1:
The patent removes phosphorus plasticizers from the formulation entirely, achieving flexibility through the polyamide-grafted functionalized polyolefin structure itself without relying on plasticizing agents that would exude or increase phosphorus content above acceptable levels
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 compositions exhibit excellent flame propagation resistance, high thermomechanical properties, and thermal stability, retaining 70% of initial mechanical properties after thermal aging, with no exudation, and are suitable for various applications including cabling and electrical components.
Implementation Method 1
containing at least one flame retardant, based more particularly on ammonium polyphosphates
Implementation Method 2
containing at least one flame retardant, based more particularly on ammonium polyphosphates, and a zeolite
Implementation Method 3
based on functionalized polyolefins grafted with polyamide units
Implementation Method 4
retaining 70% of initial mechanical properties after thermal aging
Data Source
AI summary
The invention concerns flexible high thermomechanical stress-resistant and fire retardant halogen-free thermoplastic compositions, comprising a polyamide block-graft copolymer consisting of a trunk and on average at least one polyamide graft, wherein the grafts are bound to the trunk by the residues of an unsaturated monomer (X) having a function capable of reacting with a polyamide at the amine-terminal, the unsaturated monomer residues (X) being bound on the trunk by grafting or copolymerization from the double bond thereof. The invention is characterized in that the compositions comprise a mixture: 50 to 70 wt. % of polyamide block copolymer, 25 to 35 wt. % of a flame-retardant agent selected among ammonium phosphates, phosphinates, pyrophosphates, and polyphosphates, about 2 wt. % of zeolite, or hydrotalcitemolecular sieves. Said compositions are particularly useful for making electric cables, electric components, for molding electrotechnical housings, or for making coating layers or thermal protection sleeves for fluid transfer lines in the automotive industry.