Novolac Polyether Foam Fire Resistance
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Solution Overview
Problem
Rigid polyurethane or urethane-modified polyisocyanurate foams require improved fire properties and faster curing times while minimizing the use of flame retardants, particularly brominated ones, which often compromise physical properties and increase costs.
Innovation Solution
The combination of ethoxylated polyether polyols with a propylene oxide tip and unmodified or modified novolac polyols provides a unique combination of fire properties and fast curing, reducing the need for high amounts of flame retardants and enhancing processing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flame retardants are added to improve fire performance, then fire resistance is improved, but physical properties such as compressive strength deteriorate and system cost increases
Solution Approach 1:
The patent removes brominated flame retardants from the foam formulation entirely, replacing them with a polyol composition containing hydroxylated liquid crystal compounds and specific polyether polyols that inherently provide fire resistance without compromising mechanical properties
Solution Approach 2:
The patent changes the chemical composition parameters of the polyol blend, specifically using hydroxylated liquid crystal compounds (10-40 wt%) and propylene oxide tipped ethoxylated polyether polyols (60-85 wt%) with controlled hydroxyl numbers and molecular weights to achieve both fire resistance and mechanical strength
2Reliability
If brominated flame retardants are used to achieve fire performance standards, then fire resistance is improved, but smoke generation increases leading to lower smoke category
Solution Approach 1:
The patent converts the harmful smoke-generating property of traditional flame retardants into a benefit by using hydroxylated liquid crystal compounds that promote char formation and reduce smoke generation, transforming the fire safety approach from additive-based to composition-based fire resistance
Solution Approach 2:
The patent extracts and eliminates brominated flame retardants from the formulation, replacing them with halogen-free compounds that do not generate toxic smoke, thereby improving the smoke category rating
3Reliability
If high amounts of flame retardants are used in hydrocarbon blown foams, then fire performance is improved, but the amount of flame retardants needed increases up to 60 wt%
Solution Approach 1:
The patent fundamentally changes the formulation approach by using a polyol composition with inherent fire-resistant properties, reducing flame retardant content from up to 60 wt% to less than 10 wt% while maintaining fire performance through the synergistic effect of hydroxylated liquid crystal compounds and specific polyether polyols
Solution Approach 2:
The patent creates a composite polyol system combining hydroxylated liquid crystal compounds, propylene oxide tipped ethoxylated polyether polyols, and other polyfunctional compounds, where the composite provides both fire resistance and foam performance without requiring high amounts of separate flame retardant additives
4Ease of manufacture
If traditional polyols are used, then processing is simplified, but fire properties and curing speed are insufficient
Solution Approach 1:
The patent modifies the polyol composition by incorporating hydroxylated liquid crystal compounds and propylene oxide tipped ethoxylated polyether polyols with specific molecular weight and hydroxyl number ranges, achieving both improved fire properties and fast curing while maintaining processability
Solution Approach 2:
The patent develops a composite polyol formulation that combines multiple compounds with complementary properties, where hydroxylated liquid crystal compounds provide fire resistance and the propylene oxide tipped polyols provide reactivity and foam structure, creating a synergistic system that meets all performance 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
This approach results in foams with improved fire resistance, lower friability, and faster curing, meeting B2 fire behavior standards while reducing the amount of flame retardants required, thus addressing the limitations of traditional polyols in terms of fire performance and processing.
Implementation Method 1
reacting a polyisocyanate with isocyanate-reactive compounds (usually a polyol)
Implementation Method 2
in the presence of a blowing agent
Data Source
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AI summary
Process for preparing rigid polyurethane or urethane-modified polyisocyanurate foams from polyisocyanates and polyfunctional isocyanate-reactive compounds in the presence of blowing agents wherein the polyfunctional isocyanate-reactive compounds comprise an unmodified or modified novolac polyol and a polyether polyol having a hydroxyl number of between 50 and 650 mg KOH/g obtained by reacting a polyfunctional initiator first with ethylene oxide and subsequently with propylene oxide wherein the propoxylation degree is between 0.33 and 2 mole propylene oxide per active hydrogen atom in the initiator and wherein the molar ratio of ethylene oxide to propylene oxide in said polyether polyol is at least 2.