EPDM Rubber Composition for Fire-Safe Rail Suspension Parts
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Solution Overview
Problem
Rubber mixtures used in elastomeric articles for vehicle suspension and vibration damping fail to meet stringent fire protection standards due to high heat release rates and toxic smoke production, and existing solutions compromise physical properties or increase production complexity.
Innovation Solution
A rubber mixture composed of ethylene propylene rubber (EPM) or ethylene propylene diene rubber (EPDM) with carbon black, peroxide as a crosslinking agent, and specific co-agents, along with zinc oxide and wax, which improves fire protection without requiring additional fire-retardant additives or coatings, thus meeting the EN45545 standard without compromising physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fire-retardant substances are directly mixed into rubber mixtures to improve fire behavior, then fire protection is improved, but physical properties such as suspension, settling and vibration properties deteriorate significantly
Solution Approach 1:
The patent divides the rubber product into two distinct parts: a base body made of conventional rubber mixture (NR/IR or CR) and an outer layer made of fire-retardant elastomeric mixture. This segmentation allows each part to fulfill its specific function - the base body provides the required physical properties for suspension and vibration damping, while the outer layer provides fire protection and smoke gas suppression.
Solution Approach 2:
The fire-retardant properties are concentrated in the outer layer rather than being distributed throughout the entire rubber mixture. This local quality approach ensures that fire protection is enhanced where it is most needed (at the surface exposed to fire) while the internal structure maintains its original physical properties for mechanical function.
2Object-affected harmful factors
If an additional outer layer with fire-retardant properties is applied to improve fire behavior, then fire protection is improved, but production complexity and manufacturing costs increase
Solution Approach 1:
The patent combines the fire-retardant elastomeric mixture with the base rubber mixture through a co-vulcanization process, merging two functional materials into a single integrated product. The outer layer and base body are bonded together through simultaneous vulcanization, creating a unified structure that eliminates the need for separate assembly steps and reduces production complexity.
Solution Approach 2:
The outer layer serves multiple functions: it provides fire retardancy, suppresses smoke gas formation, and bonds structurally to the base body through co-vulcanization. This multi-functionality reduces the need for additional separate components or treatments, simplifying the overall production process.
3Object-affected harmful factors
If double vulcanization is performed to apply a fire-retardant outer layer, then fire protection is improved, but production time and costs increase
Solution Approach 1:
The outer layer is prepared with all necessary components for co-vulcanization in advance, including the fire-retardant elastomeric mixture and appropriate crosslinking agents. This preliminary preparation allows the outer layer to be applied and vulcanized together with the base body in a single continuous process, avoiding the need for a second vulcanization step.
4Object-affected harmful factors
If elastomers containing double bonds are used in the rubber mixture, then fire protection is improved, but aging susceptibility increases
Solution Approach 1:
The patent uses a composite material system where the outer layer is made of fire-retardant elastomeric mixture (which may contain double bonds) bonded to a base body of conventional rubber. The co-vulcanization process creates a integrated composite structure where the two materials work together, allowing the fire-retardant outer layer to provide its protective function while the overall composite maintains acceptable aging resistance through proper material selection and formulation.
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 rubber mixture significantly enhances fire protection to meet the highest Hazard Level 3 requirement of DIN EN 45545-2:2013-08, reducing production complexity and eliminating the need for hazardous fire-retardant additives, while maintaining essential physical properties such as elasticity and resistance.
Implementation Method 1
at least one peroxide as a crosslinking agent and at least one co-agent for peroxidic crosslinking
Implementation Method 2
at least one carbon black
Data Source
AI summary
The invention relates to a rubber mixture and to an elastic article which comprises the rubber mixture. The article is preferably an air spring bellows, a metal-rubber element, a vibration damper or a bearing, such as a box bearing or cone bearing, especially a shaped article for rubber-sprung rail vehicle wheels. To improve fire protection performance, the rubber mixture consists of constituents as follows: - 100 phr of at least one ethylene-propylene rubber (EPM) and/or of at least one ethylene-propylene-diene rubber (EPDM) and - at least one carbon black and - at least one peroxide crosslinker and - at least one co-agent for the peroxidic crosslinking and - other mixture constituents.