Fuel Cell Seal Composition for Thin Films and Low-Temperature Sealing
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Solution Overview
Problem
Existing radical-curable seal members for fuel cells face challenges in productivity, miniaturization, and maintaining sealability across a wide temperature range, particularly due to high viscosity properties of ethylene-propylene-diene rubber (EPDM) and lengthy manufacturing processes.
Innovation Solution
A radical-curable seal member composed of a crosslinked product blending a (meth)acrylic polymer with (meth)acryloyl groups, monofunctional and polyfunctional (meth)acrylic monomers, and a radical polymerization initiator, which can be formulated into a thin film with excellent compression permanent strain resistance and cracking properties within a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EPDM is used as the main component of the seal member, then good sealability is achieved, but the viscosity remains high which limits miniaturization and thin film formation
Solution Approach 1:
The patent changes the chemical composition parameters by replacing EPDM with (meth)acrylic polymers having terminal (meth)acryloyl groups, which have inherently lower viscosity. This parameter change enables the seal member to be formed into thin films while maintaining sealability, directly resolving the contradiction between high viscosity and miniaturization capability
Solution Approach 2:
The patent creates a composite material system combining (meth)acrylic polymer with terminal (meth)acryloyl groups, monofunctional (meth)acrylic monomer, polyfunctional (meth)acrylic monomer, and radical polymerization initiator. This composite approach achieves both low viscosity for thin film formation and excellent sealability through crosslinked structure formation
2Ease of manufacture
If injection molding with EPDM is used, then seal members can be manufactured, but the process takes considerable time and requires large initial investment and maintenance costs
Solution Approach 1:
The patent replaces the mechanical injection molding process with a chemical curing process. The seal member composition is applied and then cured in place through radical polymerization, eliminating the need for complex injection molding equipment and lengthy molding cycles, thereby reducing both manufacturing time and equipment investment
Solution Approach 2:
The seal member composition performs its own forming and curing process without requiring external molding equipment. The composition is applied to the sealing location and cures in situ through radical polymerization, making the manufacturing process simpler and more efficient
3Reliability
If conventional seal members are used, then sealability is maintained, but compression permanent strain resistance and compression cracking property deteriorate at low temperatures
Solution Approach 1:
The patent changes the glass transition temperature parameter by selecting (meth)acrylic polymers and monomers with appropriate Tg values. The composition is designed to have a glass transition temperature of -40°C or lower, which maintains flexibility and compression permanent strain resistance at low temperatures while preserving sealability through the crosslinked 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 solution enhances productivity, allows for miniaturization of fuel cells, and ensures excellent sealability across a wide temperature range, including low temperatures, while reducing manufacturing time and costs.
Implementation Method 1
a composition obtained by blending, at a predetermined ratio, a (meth)acrylic polymer having a (meth)acryloyl group at a molecular chain end, a monofunctional (meth)acrylic monomer, a polyfunctional (meth)acrylic monomer, and a radical polymerization initiator
Data Source
AI summary
A radical-curable seal member for fuel cell 4 having a glass transition temperature of −40° C. or lower made from a crosslinked product of a radical-curable composition containing (A) (Meth)acrylic polymer having a (meth)acryloyl group at a molecular chain end, (B) Monofunctional (meth)acrylic monomer, (C) Polyfunctional (meth)acrylic monomer and (D) Radical polymerization initiator, wherein the radical-curable composition contains 20 to 90 weight parts of component (B), 1 to 10 weight parts of component (C), 0.01 to 10 weight parts of component (D) with respect to 100 weight parts of component (A), a weight ratio [(B)/(C)] of the component (B) with respect to the component (C) being 4 to 24, and a content [(C)/{(A)+(B)+(C)}] of the component (C) with respect to a total of 100 wt % of the component (A), the component (B), and the component (C) being 1 to 7 wt %.