Halogen-Free Rubber Layers for Fire-Safe Air Spring Bellows
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Solution Overview
Problem
Articles made from elastomeric mixtures, such as air spring bellows and vibration dampers, primarily based on natural rubber (NR) and polyisoprene rubber (IR), fail to meet stringent fire safety standards due to high heat release rates and toxic smoke production, while flame-retardant additives compromise their physical properties like hardness and dynamic performance.
Innovation Solution
A rubber mixture with finely divided carbon blacks having a BET surface area between 35 and 140 m2/g and an oil absorption number between 70 and 140 ml/100 g, combined with zinc stannate or magnesium hydroxide, reduces the need for additional flame retardants, enhancing fire safety and maintaining dynamic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a soft copper layer is used for engraving, then engraving ease is improved, but wear resistance deteriorates
Solution Approach 1:
The patent divides the printing template into two functionally independent layers: a soft copper layer dedicated to engraving and a hard chromium layer dedicated to wear resistance. This segmentation allows each layer to optimize its specific function without compromise - the copper layer remains soft for easy engraving while the chromium layer provides the necessary durability.
Solution Approach 2:
The patent employs a composite structure combining copper and chromium layers. The copper layer provides excellent engraving properties due to its softness, while the chromium layer contributes superior wear resistance. This composite material approach resolves the contradiction by combining materials with complementary properties rather than relying on a single material to fulfill both requirements.
2Strength
If a hard chromium layer is applied via electroplating, then wear resistance is improved, but environmental harm and process complexity increase
Solution Approach 1:
The patent extracts and eliminates the harmful electroplating process from the production sequence. Instead of using chromium(VI) trioxide electroplating, the invention applies a hard chromium layer through alternative, environmentally friendly methods such as physical vapor deposition or chemical vapor deposition, thereby removing the toxic chromium compounds from the process while maintaining the wear resistance function.
Solution Approach 2:
The patent converts the previously harmful electroplating process into a beneficial or neutral process by replacing it with environmentally safe deposition methods. The chromium layer is still applied to provide wear resistance, but the harmful chromium(VI) trioxide is replaced with safer chromium sources or alternative coating technologies that achieve the same protective function without environmental damage.
3Reliability
If multiple layers are applied to the printing template, then functionality is improved, but manufacturing complexity and energy consumption increase
Solution Approach 1:
The patent merges the engraving function and the wear protection function into a unified two-layer structure where the copper layer and chromium layer are applied in sequence as an integrated manufacturing process. This merging allows both functions to be achieved within a single production workflow rather than requiring separate, complex processes, thereby improving functionality while controlling manufacturing complexity.
Solution Approach 2:
The patent applies the copper layer first as a preliminary step before applying the chromium layer. This preliminary action of depositing the soft copper base layer enables subsequent engraving operations, after which the hard chromium layer is applied to protect the engraved features. This sequential preliminary action organizes the manufacturing process into logical stages, improving overall functionality while maintaining manageable complexity.
4Manufacturing precision
If chromium(VI) trioxide is used for electroplating, then hard chromium layer deposition is achieved, but toxicity and disposal costs increase
Solution Approach 1:
The patent changes the chemical parameters of the chromium deposition process by replacing chromium(VI) trioxide with alternative chromium compounds or entirely different deposition methods. This parameter change maintains the ability to deposit a hard chromium layer with the required properties while eliminating the use of highly toxic chromium(VI) compounds, thereby reducing toxicity and associated disposal costs.
Data Source
AI summary
The invention relates to an article having a single-layered or multilayered main body having elastic properties, in particular an air spring bellows, a metal-rubber element or a vibration damper.To improve the flame-retardant properties the main body of the article consists of or contains at least one layer D which is constructed from a rubber mixture which is free from halogen-containing flame retardants and contains at least one carbon black having a BET surface area according to DIN-ISO 9277 between 35 and 140 m2/g and an oil absorption number (OAN) according to ISO 4656 between 70 and 140 ml/100 g.