Air Spring Bellows Rubber Composition for Flame Retardancy
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Solution Overview
Problem
Articles made from elastomeric mixtures, such as air spring bellows and vibration dampers, fail to meet stricter fire safety standards due to high heat release rates and toxic smoke production, while traditional flame retardants compromise physical properties like hardness.
Innovation Solution
A multi-layered article with a rubber mixture containing aluminum trihydrate (ATH) of different particle sizes and amorphous silica, along with additional flame retardants and acid scavengers, enhances fire safety without impairing hardness and cushioning properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If flame retardant substances are incorporated into rubber mixtures to improve fire safety, then flame retardancy is improved, but physical properties such as hardness are impaired
Solution Approach 1:
The patent changes the particle size parameter of aluminum trihydrate from a single size to multiple sizes (specifically using fine ATH with d50 of 0.5-2.0 μm and coarse ATH with d50 of 2.0-5.0 μm). This parameter change allows the filler to achieve both fire safety and physical property requirements, as the multi-size distribution optimizes both flame retardancy and hardness without the need for large amounts of flame retardant additives.
Solution Approach 2:
The patent creates a composite filler system combining aluminum trihydrate of different particle sizes with silane-modified polyethylene. This composite material approach allows the system to achieve synergistic effects where the fine ATH provides fire safety, the coarse ATH maintains structural integrity and hardness, and the silane-modified polyethylene enhances the interface between filler and rubber matrix, thereby maintaining physical properties while achieving flame retardancy.
2Object-affected harmful factors
If large amounts of flame retardant substances are used to achieve fire safety requirements, then flame retardancy is improved, but cushioning and vibration properties are impaired
Solution Approach 1:
The patent optimizes the particle size distribution parameter of aluminum trihydrate, using a bimodal distribution with fine particles (d50 of 0.5-2.0 μm) for fire safety and coarse particles (d50 of 2.0-5.0 μm) for maintaining mechanical properties. This parameter optimization allows achieving flame retardancy with reduced total filler content, thereby preserving cushioning and vibration properties.
Solution Approach 2:
The patent applies different particle sizes of aluminum trihydrate to different functional requirements: fine ATH particles primarily contribute to flame retardancy, while coarse ATH particles primarily maintain mechanical strength and cushioning properties. This local quality differentiation allows each component to excel at its specific function without compromising the other.
3Strength
If conventional elastomeric mixtures are used to maintain physical properties, then hardness and cushioning are maintained, but smoke toxicity and heat release rate are too high
Solution Approach 1:
The patent changes the chemical composition parameter by replacing conventional carbon black fillers with a multi-size aluminum trihydrate-silane modified polyethylene composite system. This parameter change reduces smoke toxicity and heat release rate while the specific particle size distribution (fine and coarse ATH) maintains the hardness and cushioning properties through optimized filler-rubber interaction.
Solution Approach 2:
The patent converts the typically harmful effect of filler aggregation into a benefit by using silane-modified polyethylene to create a controlled interface between aluminum trihydrate particles and rubber matrix. This controlled interface prevents harmful aggregation while maximizing the fire safety benefits of ATH, and the multi-size distribution ensures that both fine and coarse particles contribute positively to the overall performance.
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 significantly improves flame retardancy and reduces smoke toxicity, meeting stricter fire safety requirements like EN45545 Hazard Level 3 without sacrificing physical properties, especially hardness, in dynamically stressed articles.
Implementation Method 1
the use of two ATH which have different particle sizes in combination with silicic acid having spherical particle geometry in rubber mixtures and in articles which contain at least one such rubber mixture shows improved flame retardancy
Implementation Method 2
Article having elastic properties, in particular air spring bellows, a metal-rubber element or a vibration damper
Implementation Method 3
Articles having elastic properties that are used for the suspension of, for example, motor vehicles or track vehicles and/or vibration damping
Data Source
AI summary
The invention relates to an article having a single- or multi-layered main body having elastic properties, in particular an air spring bellows, a metal-rubber element or a vibration damper.In order to improve its flame retardant properties, the main body of the article consists of or contains at least one layer D constructed from a rubber mixture which is free from halogen-containing flame retardants and contains a first aluminum trihydrate (ATH_1) and at least one further aluminum trihydrate (ATH_2) and at least one amorphous silicic acid having spherical particle geometry, wherein the first aluminum trihydrate (ATH_1) and the further aluminum trihydrate (ATH_2) each have a different particle size.