Hydraulic Hose Cover Composition for Fire Resistance and Flexibility
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Solution Overview
Problem
Rubber hoses used in railway applications face stringent fire test requirements due to the EN 45545-2:2013 norm, which demands severe fire resistance, low smoke density, and non-toxic gas emission, while existing materials often fail to meet these conditions effectively, especially in terms of flexibility and halogen-free composition.
Innovation Solution
A rubber composition for the cover layer of hydraulic hoses comprising ethylene vinyl acetate copolymer (EVA) and ethylene-propylene-diene terpolymer (EPDM), combined with halogen-free flame retardants like aluminium hydroxide and magnesium hydroxide, which provides improved flame retardancy, low smoke density, and flexibility, while remaining ozone-, UV-, and weather-resistant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rubber materials are used to meet fire resistance requirements, then flame retardancy is improved, but flexibility and low-temperature performance deteriorate
Solution Approach 1:
The patent uses a composite rubber composition comprising EPDM (50-90 phr), EVA (10-50 phr), and specific additives including aluminium hydroxide (20-80 phr) and magnesium hydroxide (10-50 phr). This composite formulation combines the flame-retardant properties of halogen-free fillers with the flexibility of elastomeric polymers, achieving both fire resistance (LOI ≥ 28%) and flexibility at -40°C without mutual compromise
2Object-generated harmful factors
If halogen-free flame retardants are used, then environmental safety is improved, but smoke density and toxic gas emission control become more difficult
Solution Approach 1:
The patent optimizes the dosage parameters of flame retardants (aluminium hydroxide: 20-80 phr, magnesium hydroxide: 10-50 phr) and their combination ratios to achieve the desired balance. By precisely controlling these parameters, the composition achieves low smoke density (DSmax ≤ 600) and minimal toxic gas emission (CITNLP ≤ 1.2) while maintaining halogen-free status
3Reliability
If severe fire test requirements are met, then safety is improved, but material selection and formulation complexity increase
Solution Approach 1:
The patent assigns specific functional roles to different components: EPDM provides base elastomeric properties and flexibility, EVA enhances low-temperature performance and processability, aluminium hydroxide contributes to flame retardancy and smoke suppression, and magnesium hydroxide provides additional fire resistance. This functional differentiation allows each component to be optimized independently while achieving comprehensive fire resistance (EN 45545-2:2013 compliance)
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 composition meets the EN 45545-2:2013 and SAE J517 100R4 standards by requiring high oxygen for burning, emitting minimal toxic gases, and maintaining flexibility at -40°C, thus ensuring safety and environmental sustainability.
Implementation Method 1
halogen-free flame retardants like aluminium hydroxide and magnesium hydroxide, which provides improved flame retardancy, low smoke density
Implementation Method 2
requiring high oxygen for burning, emitting minimal toxic gases
Data Source
AI summary
A rubber composition for a cover layer of a hydraulic hose includes: ethylene vinyl acetate copolymer (EVA); and ethylene-propylene-diene terpolymer (EPDM). In an embodiment, the composition includes ethylene vinyl acetate copolymer (EVA) and ethylene-propylene-diene terpolymer (EPDM) and additives. The additives may include carbon black with a content of around 15 phr, silica with a content of around 20 phr, di-octyl adipate with a content of around 18 phr, aluminium hydroxide with a content of around 124 phr, magnesium hydroxide with a content of around 30 phr, and other chemicals with a content of around 20 phr. The other chemicals may include zinc oxide, peroxide curative, antioxidant, coagents and processing aids.