Aerosol Foam Formulation Homogeneous Graphite Dispersion
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Solution Overview
Problem
Existing one component polyurethane foam formulations struggle to achieve homogeneous distribution of expandable graphite, leading to non-uniform fire retardant properties, especially when using low residual monomeric isocyanate content and without conventional halogen-based plasticizers and fluorine-containing propellants.
Innovation Solution
A process involving the addition of expandable graphite to a preformed polymer after partial prepolymerization, followed by mixing with propellant in a sealed aerosol container, ensuring a stable and homogeneous dispersion of graphite in the foam forming composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid ingredients (expandable graphite) are added to traditional one component aerosol PU foams, then fire retardant properties are improved, but separation and settling of solids occurs in the can
Solution Approach 1:
The patent changes the viscosity parameter of the liquid mixture by selecting specific propellants and adjusting their ratios to achieve a viscosity range of 50-500 cP at 20°C. This optimized viscosity parameter prevents solid graphite particles from settling while maintaining homogeneous distribution throughout the aerosol can during storage and dispensing.
Solution Approach 2:
The patent uses the propellant mixture as an intermediary medium that mediates between the solid graphite particles and the liquid components. By carefully selecting propellants and adjusting their composition, the mixture acts as a stabilizing intermediary that keeps solid particles suspended uniformly without requiring additional dispersing agents or complex mixing mechanisms.
2Reliability
If conventional halogen-based plasticizers and fluorine-containing propellants are used, then fire retardant properties are achieved, but environmental regulations restrict their use
Solution Approach 1:
The patent extracts and removes harmful halogen-based plasticizers and fluorine-containing propellants from the formulation. Instead, it uses expandable graphite particles as the primary fire retardant mechanism, eliminating the need for restricted chemicals while maintaining or improving fire safety performance.
Solution Approach 2:
The patent creates a composite aerosol formulation combining expandable graphite particles with a specially designed propellant-liquid mixture. This composite structure provides fire retardant properties through the graphite's physical expansion mechanism rather than chemical halogen release, achieving both performance and environmental compliance.
3Strength
If low residual monomeric isocyanate content is used in the prepolymer, then foam softness is improved, but fire retardant properties become more difficult to achieve
Solution Approach 1:
The patent converts the potential disadvantage of low isocyanate content (reduced fire retardancy) into a benefit by using expandable graphite as the primary fire retardant mechanism. The graphite particles compensate for the reduced chemical fire resistance, allowing soft foams to achieve required fire safety ratings through physical expansion rather than chemical inhibition.
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 method achieves a homogeneous distribution of expandable graphite in the foam, maintaining fire retardant properties throughout the shelf life of the aerosol can, even at low isocyanate content and without halogen-based additives.
Implementation Method 1
expandable graphite with a mean particle size of from 0,01 to 2 mm... fire retardant properties
Implementation Method 2
The prepolymer hardens upon contact with the air humidity
Implementation Method 3
pressurized container... extrusion of the foam forming composition from a pressurized container
Data Source
AI summary
This invention relates to a method for producing a one component foam forming composition which contains at least one organic prepolymer composition for producing a fire retardant foam upon extrusion of the foam forming composition from a pressurized container, wherein the prepolymer composition and an amount of expandable graphite are supplied to the container, after which the container is sealed and pressurized by injection of at least part of the pressurized propellant into the closed container and the contents of the container are subjected to motion to cause mixing of the prepolymer, the expandable graphite and the propellant.