Fluorinated Polymer Cooling for Membrane Breakage
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Solution Overview
Problem
The existing processes for forming catalyst layers and polymer electrolyte membranes in polymer electrolyte fuel cells often result in breakage during the drying process, making it difficult to maintain the desired shape and forming a uniform layer.
Innovation Solution
A process involving the cooling of a fluorinated polymer with -SO2F groups to convert them into ion exchange groups, followed by mixing with a liquid medium to create a liquid composition with controlled viscosity, which is then used to form a catalyst layer-forming coating liquid, thereby preventing breakage during drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the concentration of the fluorinated polymer in the catalyst layer-forming coating liquid or the liquid composition is increased to increase viscosity and prevent breakage, then the mechanical strength is improved, but the liquid composition is easily gelled and uniform formation becomes difficult
Solution Approach 1:
The patent applies parameter changes by controlling the cooling rate of the fluorinated polymer during production. Specifically, the cooling rate is maintained at 45°C/min or slower in the temperature range of 110-130°C, which prevents excessive gelation while achieving the desired viscosity and mechanical strength in the final product
2Strength
If the viscosity of the catalyst layer-forming coating liquid or the liquid composition is increased to prevent breakage during drying, then the mechanical strength is improved, but the uniformity of the formed layer deteriorates
Solution Approach 1:
The patent controls the viscosity parameter through specific cooling rate parameters during production (45°C/min or slower in the 110-130°C range), which achieves the optimal balance between mechanical strength and uniformity of the formed layer without excessive gelation
3Productivity
If the cooling rate of the fluorinated polymer is increased to improve production efficiency, then the productivity is improved, but the breakage during drying increases
Solution Approach 1:
The patent identifies and controls the critical cooling rate parameter (45°C/min or slower in the 110-130°C range) that prevents breakage during drying while maintaining production efficiency, resolving the contradiction between speed and quality
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
This method effectively suppresses breakage during the drying of catalyst layers and polymer electrolyte membranes, ensuring a stable and uniform formation, which is crucial for the performance of polymer electrolyte fuel cells.
Implementation Method 1
cooling a fluorinated polymer having -SO2F groups at a temperature of higher than 130°C and at most 320°C, at a cooling rate of at most 45°C/min at least in a temperature region of from 110 to 130°C
Implementation Method 2
applying and drying a liquid composition containing a polymer having ion exchange groups and a liquid medium
Data Source
Figure 1~2
AI summary
To provide a process for producing a liquid composition capable of forming a polymer electrolyte membrane of which breakage at the time of drying is suppressed; a process for producing a catalyst layer-forming coating liquid capable of forming a catalyst layer of which breakage at the time of drying is suppressed; and a method for producing a membrane/electrode assembly by which a catalyst layer or a polymer electrolyte membrane of which breakage at the time of drying is suppressed, can be formed. A process for producing a liquid composition, which comprises holding a fluorinated polymer having -SO2F groups at from 110 to 130°C for at least 45 minutes; cooling the fluorinated polymer having -SO2F groups held at from 110 to 130°C to less than 110°C; converting the -SO2F groups in the fluorinated polymer having -SO2F groups cooled to less than 110°C to ion exchange groups thereby to obtain a fluorinated polymer having ion exchange groups; and mixing the fluorinated polymer having ion exchange groups and a liquid medium.