Fuel Cell Separator Sealing Rubber for Wide-Temperature Compression Set
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Solution Overview
Problem
Existing sealing materials for fuel cell separators lack sufficient cold resistance and high-temperature sealing properties, with EPDM compositions exhibiting reduced rubber strength and elasticity at low temperatures, and insufficient performance in high-temperature regions.
Innovation Solution
A rubber composition comprising ethylene-butene-non-conjugated diene terpolymer rubber, carbon black with specific iodine adsorption and DBP oil absorption, a linear hydrocarbon-based softener, and an organic peroxide, optimized to balance properties for wide temperature resistance and sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EPDM is used as sealing material for fuel cell separators, then adhesion reliability and sealing properties are improved, but cold resistance is insufficient
Solution Approach 1:
The patent uses a composite rubber composition comprising EPDM (50-90 parts), ethylene-α-olefin copolymer (10-50 parts), and specific additives. This composite structure combines the excellent adhesion and sealing properties of EPDM with the low-temperature flexibility of ethylene-α-olefin copolymer, achieving both high reliability and cold resistance simultaneously.
Solution Approach 2:
The patent modifies the chemical composition parameters of the rubber material by incorporating specific ratios of EPDM and ethylene-α-olefin copolymer, along with controlled amounts of crosslinking agents and coupling agents. This parameter optimization enables the material to maintain both strong adhesion and low-temperature performance.
2Reliability
If crosslinking is performed at high temperature to improve sealing properties, then sealing performance is enhanced, but electrolyte membrane degradation occurs
Solution Approach 1:
The patent changes the crosslinking temperature parameter from conventional high temperature (150-200°C) to low temperature (80-120°C) by selecting organic peroxide crosslinking agents with appropriate half-life temperatures. This enables achieving good sealing performance without degrading the electrolyte membrane.
Solution Approach 2:
The patent introduces an intermediary crosslinking system using organic peroxide and coupling agent that enables crosslinking to proceed at lower temperatures. This intermediary mechanism allows the sealing material to cure effectively without exposing the electrolyte membrane to harmful high temperatures.
3Temperature
If plasticizer is added to improve low temperature properties, then cold resistance is enhanced, but rubber strength and elasticity are reduced
Solution Approach 1:
Instead of using plasticizers that compromise strength, the patent creates a composite material system where ethylene-α-olefin copolymer serves as a co-rubber component. This composite approach maintains rubber strength and elasticity while providing low-temperature flexibility through the copolymer's molecular structure.
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 achieves excellent compression set characteristics and elongation, ensuring durability and resistance to compression cracking across a wide temperature range, making it suitable for fuel cell separator applications.
Implementation Method 1
carbon black having an iodine adsorption of 10 to 25 mg/g
Implementation Method 2
an organic peroxide crosslinking agent having a one-hour half-life temperature of 130° C. or less
Data Source
AI summary
A rubber composition having, based on 100 parts by weight of (A) a copolymer rubber polymer that includes at least one of ethylene-butene-non-conjugated diene terpolymer rubber, ethylene-propylene-non-conjugated diene terpolymer rubber, and ethylene-propylene copolymer rubber, 35 to 55 parts by weight of (B) carbon black having an iodine adsorption of 10 to 25 mg/g and a DBP oil absorption of 30 to 140 ml/100 g, 5 to 23 parts by weight of (C) a linear hydrocarbon-based softener having a kinematic viscosity at 40° C. of 8 to 500 mm2/sec and a pour point of −30° C. or less, and 0.5 to 10 parts by weight of (D) an organic peroxide.