Halogen-Free Silicon-Phosphorus-Nitrogen Polymer Flame Retardant
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Solution Overview
Problem
Conventional phosphorus and nitrogen-based intumescent flame retardant systems require high loadings, which can compromise the physical and electrical properties of polymer compositions, and suffer from migration issues at low molecular weights, while halogen-free alternatives aim to reduce these drawbacks.
Innovation Solution
A process for synthesizing intumescent, halogen-free silicon-phosphorus-nitrogen (SPN) polymers through specific reactions involving dihalosilanes, diamines, and polyhydric alcohols to produce polymers that can be used at lower loadings without sacrificing polymer matrix properties, including the use of dichlorodiphenylsilane and ethane-1,2-diamine to form N,N-(diphenylsilanediyl)diethane-1,2-diamine and pentaerythritol-spirodichlorophosphate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high loadings of conventional phosphorus and nitrogen based intumescent flame retardant are incorporated into polymer matrix, then flame retardancy is improved, but physical, electrical, and aging properties of the polymer composition are sacrificed
Solution Approach 1:
The invention changes the chemical composition parameters of the flame retardant system by incorporating silicon, phosphorus, and nitrogen in specific ratios (Si:P:N = 1:(2-4):(2-4)), and by using a polymeric structure with controlled molecular weight (5,000-50,000 g/mol). These parameter changes enable achieving UL94 V0 flame rating at lower loadings (10-30 wt%) compared to conventional systems, thereby preserving the physical properties of the polymer matrix.
Solution Approach 2:
The invention creates a composite flame retardant system combining silicon-containing compounds (such as silane-modified polyphosphazene or polysiloxane-phosphonate copolymers) with phosphorus-nitrogen intumescent components. This composite approach synergistically enhances flame retardancy while reducing the total loading required, thus maintaining the mechanical and electrical properties of the base polymer.
2Quantity of substance
If low molecular weight phosphorus and nitrogen based intumescent flame retardant is used, then loading requirements are reduced, but migration of the flame retardant occurs
Solution Approach 1:
The invention optimizes the molecular weight parameter of the polymeric flame retardant to be in the range of 5,000-50,000 g/mol. This specific molecular weight range provides an optimal balance: low enough to reduce loading requirements (10-30 wt% for UL94 V0 rating) but high enough to prevent migration and ensure compositional stability within the polymer matrix.
Solution Approach 2:
The invention introduces functional groups (such as silane groups, hydroxyl groups, or carboxyl groups) at specific locations along the polymer chain that enhance interfacial interaction with the polymer matrix. This local quality enhancement through functional group incorporation prevents migration while maintaining low molecular weight and low loading requirements.
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 resulting IHFSPN polymers provide effective flame retardancy at lower loadings than conventional systems, maintaining the integrity of polymer matrices and preventing migration, as demonstrated by achieving a UL94 V0 rating with 25% loading, outperforming conventional ammonium polyphosphate-based formulations.
Implementation Method 1
contacting at reaction conditions the silanediyldiamine and the spirodihalophosphate to produce a polymer Formula (I)
Data Source
AI summary
This invention provides intumescent, halogen-free, polymeric, silicon-phosphorus-nitrogen (SPN) flame retardant, a process for their preparation, and systems, compositions and articles into which they are incorporated. The inventive intumescent, halogen-free, SPN polymer compositions afford good flame retardant performance at a lower loading compared to conventional phosphorus and nitrogen based intumescent flame retardant compositions.