EPDM Rubber Composition for Fuel Cell Hoses With Low Ion Release
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Solution Overview
Problem
Existing rubber compositions for hoses in fuel cell systems, particularly those used in hydrogen fuel cell electric vehicles, face issues with ion release into the conveyed fluid, insufficient electrical resistivity, and processing difficulties, which affect the reliability and performance of the hoses.
Innovation Solution
A rubber composition comprising specific amounts of semi-reinforcing carbon black, lamellar inorganic filler, a processing aid system, and a plasticizing system, along with a peroxide crosslinking system, is used to enhance processability and achieve high electrical resistivity and minimized ion release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If usual EPDM-based rubber compositions are used, then resistance to swelling and impermeability to coolant are improved, but ion release into the fluid increases and volume electrical resistivity decreases
Solution Approach 1:
The patent changes the chemical composition parameters by replacing metal-based additives with alternative organic additives and adjusting the ratio of EPDM to other elastomers. Specifically, it uses 70-90 phr EPDM combined with 10-30 phr other elastomers (such as FKM or VMQ), and replaces traditional metal additives with organic peroxide crosslinking agents and calcium carbonate fillers, thereby reducing ion release while maintaining swelling resistance
Solution Approach 2:
The patent extracts and removes harmful metal-based additives from the traditional EPDM composition. It explicitly eliminates metal oxides, metal sulfides, and metal soaps that cause ion release, retaining only non-metallic components such as organic peroxides for crosslinking and calcium carbonate for reinforcement, thus solving the electrical conductivity problem
2Strength
If metal additives are used in EPDM compositions, then crosslinking and mechanical properties are improved, but volume electrical resistivity decreases due to metal ion release
Solution Approach 1:
The patent replaces durable but harmful metal-based crosslinking agents and additives with non-metallic alternatives that do not release ions. It uses organic peroxides (such as dicumyl peroxide) for crosslinking and calcium carbonate as filler, which are inert regarding ion release, thereby achieving mechanical strength without compromising electrical resistivity
Solution Approach 2:
The patent introduces non-metallic intermediary substances to replace metal additives. Organic peroxides serve as intermediaries for crosslinking instead of metal oxides, and calcium carbonate serves as an intermediary filler instead of metal sulfides or soaps, maintaining mechanical properties while preventing ion contamination
3Ease of manufacture
If traditional EPDM composition is used, then processing is simplified, but extrudability and processability under satisfactory conditions are insufficient
Solution Approach 1:
The patent optimizes the compositional parameters to balance processability and extrudability. It adjusts the EPDM content to 70-90 phr and adds 10-30 phr of other elastomers with different viscosity characteristics, creating a blend that flows better during extrusion while maintaining ease of manufacturing. The use of calcium carbonate filler also improves processability by reducing stickiness
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 composition ensures high volume resistivity, reduced ion release, and improved processability, making it suitable for forming hoses that minimize electrochemical degradation and prevent short circuits in fuel cell systems.
Implementation Method 1
a crosslinking system comprising a peroxide
Implementation Method 2
a filler comprising carbon black and a lamellar inorganic filler
Data Source
AI summary
The invention relates to a rubber composition based on at least one EPM copolymer or one EPDM terpolymer, and a rubber article incorporating it, such as a seal or a pipe (10) e.g. for an air, water, or cooling circuit equipping a fuel cell.The composition comprises:a filler comprising a carbon black and a lamellar inorganic filler,a processing aid system,a plasticizing system, anda crosslinking system comprising a peroxide,wherein the composition comprises, in mass percents:28-32% of carbon black, which is chosen from theASTM N600 or N700 series of blacks, andthose having a specific surface area of 15-25 m2/g, an iodine adsorption index of 16-24 mg/g, and a DBP absorption index of 90-110 mL/100 g,10-20% of the lamellar inorganic filler,1.0-6.0% of the processing aid system, which comprises a carbon black covering agent, and10-22% of the plasticizing system.