Polyurethane-urea Coating with Expanded Graphite for Smoke Suppression
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Solution Overview
Problem
Existing flame retardant coating agents, such as halogen-based, phosphorous, and inorganic agents, face limitations in effectively preventing toxic smoke release and maintaining flame retardancy at high temperatures, making them unsuitable for use on building and marine structures.
Innovation Solution
A polyurethane-urea hybrid coating agent composition incorporating expanded graphite, with a binary composition of a hardening agent and a main material, including polyphosphate-based and inorganic flame retardants, ether-type polyols, and a chain extender, which forms a film that self-extinguishes within seconds when exposed to high temperatures without emitting toxic black smoke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If halogen-based flame retardant agents are used, then low cost is achieved, but toxic gases are emitted in large amounts upon combustion
Solution Approach 1:
The patent uses a composite flame retardant system combining expanded graphite (carbonaceous material) with phosphorous compounds and inorganic additives. This multi-component composite approach achieves effective flame retardancy without the toxic emissions associated with halogen-based agents, while maintaining cost-effectiveness through the use of relatively inexpensive materials like expanded graphite and common inorganic flame retardants.
Solution Approach 2:
The patent converts the potential harm of organic flame retardants into benefit by using expanded graphite that forms a protective char layer during combustion. This carbonaceous char acts as a physical barrier that prevents further decomposition and toxic gas release, transforming the combustion process from harmful to protective.
2Reliability
If phosphorous flame retardants are used, then flame retardant effect is improved (2 to 4 times higher than halogen-based), but toxic gas reduction effects are slight under high temperature ignition
Solution Approach 1:
The patent combines phosphorous flame retardants with expanded graphite and inorganic additives to create a composite system where each component compensates for the others' limitations. The expanded graphite provides high-temperature stability and physical barrier properties, while phosphorous compounds contribute to flame inhibition, achieving both effective flame retardancy and reduced toxic emissions even at 1600°C.
Solution Approach 2:
The patent creates different functional zones within the coating system: the expanded graphite forms a carbonaceous char layer at the surface providing physical protection, while phosphorous compounds act in the bulk material for chemical flame inhibition. This spatial differentiation of functions allows the system to maintain effectiveness across a wide temperature range.
3Temperature
If inorganic flame retardant agents are used, then flame retardancy is exhibited at 600°C or less, but flame retardant effect is not almost exhibited at ultrahigh temperature above 600°C unless applied in amount of 70% or more
Solution Approach 1:
The patent creates a hybrid flame retardant system combining inorganic agents (for low-temperature effectiveness), expanded graphite (for high-temperature structural stability and char formation), and phosphorous compounds (for chemical flame inhibition). This composite approach allows the coating to maintain flame retardancy across the entire temperature range from ambient to 1600°C without requiring excessive additive content.
Solution Approach 2:
The patent utilizes phase transitions and chemical transformations of the expanded graphite under heat. The graphite expands and forms a stable carbonaceous char structure that maintains integrity at ultrahigh temperatures, providing continuous physical protection even when inorganic additives become less effective above 600°C.
4Reliability
If expandable graphite is used as flame retardant, then flame retardancy is improved, but other properties need to be enhanced and convenience is still problematic
Solution Approach 1:
The patent formulates a ready-to-use coating composition where expanded graphite is pre-combined with phosphorous compounds, inorganic additives, polyols, and chain extenders in optimized proportions. This pre-formulated composite eliminates the need for users to separately mix multiple components, improving convenience while maintaining the superior flame retardancy provided by the expanded graphite.
Solution Approach 2:
The patent creates a multi-functional coating system where the expanded graphite provides not only flame retardancy but also contributes to the coating's mechanical properties, thermal stability, and char-forming capability. The phosphorous and inorganic additives provide additional flame inhibition mechanisms, creating a universal coating that addresses multiple performance requirements simultaneously.
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 composition effectively prevents the release of toxic black smoke and exhibits superior flame retardancy even at 1600°C, ensuring safety and environmental protection by self-extinguishing within several seconds upon ignition.
Implementation Method 1
a method of imparting inflammability through formation of porous char (carbonized core) in the combustion by coating foamed polystyrene resin particles with expanded graphite particles
Implementation Method 2
expanded graphite particles, which have a layered crystalline structure and are expended 20 to 350 fold in size when heated
Implementation Method 3
the composition effectively prevents the release of toxic black smoke and exhibits superior flame retardancy even at 1600°C, ensuring safety and environmental protection by self-extinguishing within several seconds upon ignition
Data Source
AI summary
Disclosed are a flame retardant polyurethane-urea hybrid coating agent composition containing expanded graphite and a method of preparing the same. More particularly, it relates to a flame retardant polyurethane-urea hybrid coating agent composition which is formed as a film on surfaces of coated structures, when coated on the interiors and exteriors of building structures, vessels, and marine structures, and, after the film formation, does not discharge toxic gases, particularly black smoke, and has a characteristic to self-extinguish within several seconds, in case of fire, and a method of manufacturing the same.