Fire Retardant Coating Composition with Expandable Graphite
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Solution Overview
Problem
Current air barrier coatings are highly flammable and struggle to achieve a balance between water vapor impermeability, mechanical properties like low temperature flexibility, and high elongation, while also meeting fire safety regulations, as they often require high loading levels of flame retardants that compromise mechanical properties or increase water vapor permeability.
Innovation Solution
A coating composition incorporating expandable graphite, film-forming latex polymers, and hydrophobic thickeners in an aqueous latex coating, optionally with metal hydroxides or zinc borate, which forms a vapor-impermeable film with less than one perm permeability and maintains mechanical integrity, allowing for effective fire retardancy and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high loading levels of flame retardants are incorporated into air barrier coatings to meet fire safety regulations, then fire retardancy is improved, but mechanical properties such as flexibility and elongation deteriorate
Solution Approach 1:
The patent extracts the flame retardant function from the polymer matrix by using expandable graphite particles that expand independently when exposed to heat, creating a protective barrier without requiring high concentrations of flame retardant additives that would compromise mechanical properties
Solution Approach 2:
The patent creates a composite coating system combining expandable graphite particles with a polymer matrix, where the graphite provides fire protection through expansion while the polymer maintains mechanical integrity, achieving both fire safety and flexibility
2Reliability
If hydrated mineral fillers such as magnesium hydroxide and aluminum trihydroxide are used as flame retardants, then fire spread is reduced, but water vapor permeability increases
Solution Approach 1:
The patent replaces hydrated mineral fillers with expandable graphite particles that do not contain water molecules, eliminating the source of increased water vapor permeability while maintaining fire protection through thermal expansion and char formation
Solution Approach 2:
The patent changes the chemical composition parameter from hydrated minerals to anhydrous expandable graphite, fundamentally altering how fire protection is achieved from water generation to physical barrier formation through expansion
3Reliability
If clays are incorporated into polar polymers to improve fire retardant properties, then flame spread is reduced, but water vapor permeability increases due to hygroscopic nature
Solution Approach 1:
The patent removes hygroscopic clays from the formulation and replaces them with expandable graphite particles that do not absorb water vapor, eliminating the permeability problem while retaining fire protection through expansion mechanism
4Reliability
If phosphorous-containing polymers are used to improve fire retardancy, then flame spread is reduced, but water vapor permeability increases
Solution Approach 1:
The patent extracts the fire protection function from phosphorous-containing polymers and implements it through expandable graphite particles, separating the fire retardancy mechanism from water vapor permeability issues
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 solution provides a water vapor-impermeable, flexible, and fire-resistant coating that meets stringent building codes by using expandable graphite to minimize flammable vapor release and maintain mechanical properties, effectively addressing the limitations of existing air barrier coatings.
Implementation Method 1
expandable graphite to minimize flammable vapor release and maintain mechanical properties
Implementation Method 2
at least one hydrophobic thickener for suspending the polymer and graphite within an aqueous latex coating
Implementation Method 3
at least one film-forming latex polymer
Data Source
AI summary
A fire retardant, vapor impermeable coating composition is disclosed which is useful for protecting gypsum, wood, polyurethane, polystyrene, and other construction materials and surfaces, such as components for buildings. The composition does not require halogenated compounds and is considered environmentally friendly. The composition is provided in the form of a liquid-applicable aqueous latex comprising at least one latex polymer and an expandable graphite, optionally a hydrophobic thickener, and optionally other fire retardants such as metal hydroxides, wherein the polymer is selected such that the composition, when coated onto a substrate and allowed to dry, has a vapor permeability not exceeding one perm (5.70×10−8 g/Pa·s·m2 when tested according to ASTM E96B-10 at an average dry film thickness of 40 mils). The invention provides fire retardant air barrier layers for construction materials, such as polyurethane or polystyrene insulation beads or panels, as well as vapor impermeable laminates for construction applications.