Polyurethane Foam Flame Retardancy Density Control
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Solution Overview
Problem
Conventional polyurethane foams used in vehicle parts face challenges in achieving low combustibility and suppressing discoloration while maintaining low density, as increasing the water content as a blowing agent leads to self-ignition and discoloration due to exothermic temperature increases, and existing flame retardants either lack effectiveness or come with environmental and manufacturing cost issues.
Innovation Solution
A polyurethane foam is developed using a raw material composition that includes expanded graphite for flame retardancy and an inorganic compound hydrate to suppress discoloration, which reacts and foams to produce a foam with low combustibility and reduced exothermic temperature, achieving a balance of low density and safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the content of water as a blowing agent is increased to reduce the apparent density of polyurethane foam to 20 kg/m3 or less, then the density is reduced and weight is saved, but the exothermic temperature increases to 170°C or higher causing self-ignition and discoloration
Solution Approach 1:
The patent introduces an intermediary substance (fire retardant) that mediates between the blowing agent and the polyurethane foam system. This fire retardant acts as a heat sink and chemical inhibitor, absorbing excess heat and preventing the exothermic reaction from reaching self-ignition temperatures, thus enabling the use of higher water content for density reduction without causing discoloration or combustion
Solution Approach 2:
The patent changes the chemical composition parameters of the raw material system by adding specific fire retardants and adjusting their concentrations. This parameter change modifies the thermal and chemical properties of the system, allowing the exothermic temperature to be controlled at lower levels even with increased water content, thereby resolving the contradiction between density reduction and temperature control
2Reliability
If a flame retardant is blended with polyurethane foam to provide low combustibility, then fire safety is improved, but the apparent density increases making the material heavier
Solution Approach 1:
The patent applies local quality by concentrating the fire retardant function in specific additive components rather than uniformly increasing the overall material density. The fire retardant is introduced as a targeted functional ingredient that provides flame resistance locally at the molecular level within the foam structure, maintaining overall low density while achieving fire safety requirements
Solution Approach 2:
The patent creates a composite material system combining polyurethane foam with fire retardant additives. This composite approach integrates multiple materials with complementary properties: the polyurethane provides the foam structure and insulation, while the fire retardant additive provides flame resistance. The composite material achieves both low density and fire safety through synergistic combination of components
3Object-affected harmful factors
If methylene chloride is used as a blowing auxiliary to prevent discoloration, then discoloration is suppressed, but environmental harm increases and usage is regulated
Solution Approach 1:
The patent replaces the harmful methylene chloride with alternative blowing auxiliaries that are environmentally friendly and not subject to usage restrictions. These alternative substances may have shorter operational lifecycles or be more easily degraded, but they eliminate the persistent environmental harm associated with methylene chloride while still achieving the discoloration prevention function
Solution Approach 2:
The patent changes the chemical parameters of the blowing auxiliary system by substituting methylene chloride with different substances having different chemical properties. This parameter change in the auxiliary agent's composition allows for environmentally compliant operation while maintaining the functional benefit of discoloration suppression through alternative chemical mechanisms
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 foam exhibits low combustibility after heat and hygrothermal aging, suppresses discoloration, and meets the required density and safety standards for vehicle parts, such as hood and dash silencers, with improved moldability and physical properties.
Implementation Method 1
an inorganic compound hydrate... which reacts and foams to produce a foam with low combustibility and reduced exothermic temperature
Implementation Method 2
it is necessary to increase the content of water as a blowing agent in a raw material of the polyurethane foam
Implementation Method 3
As a blowing auxiliary, methylene chloride and liquefied carbon dioxide may be used
Data Source
AI summary
A polyurethane foam for vehicles is obtained by reaction, foaming, and curing of a polyurethane-foam raw material comprising polyol, polyisocyanate, a blowing agent, and a catalyst, and is used for vehicle parts. The foam raw material comprises expanded graphite and an inorganic compound hydrate. The polyol preferably comprises polymeric polyol in which a polyether polyol is graft-polymerized with a vinyl monomer, polyether polyol having a mass average molecular weight of from 400 to 1,000, in which a polyhydric alcohol is addition-polymerized with an alkylene oxide, and polyether polyol having a mass average molecular weight of from 2,000 to 4,000 in which a polyhydric alcohol is addition-polymerized with an alkylene oxide.