Crosslinked Polyphosphazene Flame Retardant for Heat-Resistant Molding
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Solution Overview
Problem
Existing phosphazene compounds used as flame retardants in thermoplastic polymers, particularly polycarbonates, lead to a noticeable deterioration in heat resistance, such as reduced Vicat temperatures or glass transition temperatures, while also causing esthetic defects and mechanical property deterioration.
Innovation Solution
A polyphosphazene is produced by reacting cyclic phosphazene with phenol and an aromatic diphenol in specific molar ratios, forming a crosslinked structure that is insoluble in many solvents, which is then incorporated into thermoplastic polymers to provide flame retardancy without significantly affecting heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphazene compounds are used as flame retardants in thermoplastic polymers, then flame retardancy is improved, but heat resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molar ratios of reactants (cyclic phosphazene, phenol, and aromatic diphenol) during synthesis to produce a polyphosphazene with optimized molecular structure. This structural optimization allows the flame retardant to maintain effective phosphorus content for flame retardancy while reducing the negative impact on the polymer matrix's heat resistance through controlled crosslinking density and molecular weight distribution.
Solution Approach 2:
The invention creates a composite structure by forming a crosslinked polyphosphazene network that integrates multiple functional components: the cyclic phosphazene provides flame retardant properties, phenol contributes to crosslinking and thermal stability, and aromatic diphenol enhances structural rigidity and heat resistance. This composite approach allows the flame retardant to simultaneously achieve effective flame inhibition and minimal degradation of the polymer's thermal properties.
2Reliability
If liquid oligophosphates are used as flame retardants, then flame retardancy is improved, but mechanical properties and esthetic appearance deteriorate
Solution Approach 1:
The patent transforms the physical state parameter of the flame retardant from liquid (oligophosphates) to solid (crosslinked polyphosphazene) through controlled polymerization and crosslinking reactions. This parameter change eliminates migration to the component surface, preventing esthetic defects, while the crosslinked network structure provides mechanical reinforcement that maintains or improves the composite's mechanical properties.
Solution Approach 2:
The invention applies local quality by creating a crosslinked network structure that is distributed throughout the polymer matrix, providing localized reinforcement and anchoring the flame retardant in specific regions. This prevents migration to the surface while maintaining flame retardancy, and the crosslinked regions provide localized mechanical strength enhancement without compromising overall material properties.
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 polyphosphazene maintains the thermal properties of the polymer matrix, offering good flame retardancy with minimal impact on mechanical properties and esthetic appearance.
Implementation Method 1
A polyphosphazene is produced by reacting cyclic phosphazene with phenol and an aromatic diphenol in specific molar ratios, forming a crosslinked structure
Data Source
AI summary
The invention relates to a polyphosphazene produced by a method comprising the steps a) and b): a) converting an in particular cyclical phosphazene by means of phenol in the presence of a base; b) further converting by means of a special aromatic diphenol in the presence of a base, wherein the molar ratio of phenol used to cyclical phosphazene used is in the range from 3.5:1 to 1:1. The invention also relates to a method for producing the polyphosphazene and to a molding compound containing the polyphosphazene and a thermoplastic polymer.