Porous Fluorine Membrane Coating Uniformity via Intermediary Surfactant
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Solution Overview
Problem
Porous fluorine-based membranes face challenges in achieving uniform water and oil repellency due to high surface tension differences between water-repellent agents and the low surface tension of the membrane substrate, making smooth wetting and coating difficult, and requiring separate coating processes for both surfaces.
Innovation Solution
A porous fluorine-based resin composite membrane is developed with a coating layer containing a (co)polymer derived from perfluoroalkyl acrylate and perfluoroalkanoic acid, which is applied to both surfaces and the outer surfaces of pores in a single step, enhancing water and oil repellency and air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-repellent agents are applied to porous fluorine-based resin membrane, then water and oil repellency is improved, but coating uniformity deteriorates due to high surface tension difference between the agent and low surface tension substrate
Solution Approach 1:
The patent uses a fluorinated surfactant as an intermediary substance to bridge the surface tension gap between the water-repellent agent and the porous fluorine-based resin membrane. The surfactant modifies the surface properties of the membrane, enabling uniform coating of the water-repellent agent while maintaining its repellency function.
Solution Approach 2:
The patent changes the surface tension parameter of the membrane substrate by applying a fluorinated surfactant coating. This parameter modification allows the water-repellent agent to spread uniformly across the membrane surface, resolving the coating uniformity issue while preserving water and oil repellency.
2Reliability
If separate coating processes are used for both surfaces of the membrane, then water and oil repellency on both surfaces is achieved, but manufacturing complexity and process time increase
Solution Approach 1:
The patent merges the coating processes for both surfaces into a single simultaneous operation. The water-repellent agent is applied to the membrane in such a way that it coats both surfaces and the pore outer surfaces in one step, reducing manufacturing complexity and process time while achieving uniform repellency on all surfaces.
Solution Approach 2:
The coating process is designed to perform multiple functions simultaneously: it treats both the front and back surfaces of the membrane as well as the outer surfaces of the pores. This multi-functional approach eliminates the need for separate coating operations for each surface.
3Productivity
If liquid penetrates into both surfaces of the porous membrane, then liquid permeability is improved, but water and oil repellency properties are compromised
Solution Approach 1:
The patent applies water-repellent properties selectively to specific locations: the outer surfaces of the pores and both surfaces of the membrane. The inner pore surfaces maintain their hydrophilic nature to allow liquid penetration and filtration. This local differentiation of properties preserves both liquid permeability and water-oil repellency.
Solution Approach 2:
The patent segments the membrane surfaces into different functional zones: the outer surfaces of pores are treated with water-repellent properties to prevent liquid penetration, while the inner pore surfaces remain untreated to maintain liquid permeability. This segmentation allows simultaneous achievement of both permeability and repellency.
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 achieves excellent water and oil repellency on both surfaces of the membrane with improved air permeability, maintaining high oil repellency grades and preventing liquid penetration while maintaining mechanical stability and production efficiency.
Implementation Method 1
the water- and oil-repellent agents, which are often used to implement water and oil repellent properties on porous membranes, are mainly in the form of water dispersion and has a high surface tension. On the contrary, the porous membrane as a substrate has a low surface tension
Implementation Method 2
because of the nature of the porous material, liquid can be penetrated into both surfaces of the porous membrane
Data Source
AI summary
The present disclosure relates to a porous fluorine-based resin composite membrane having excellent water repellency and oil repellency, and a method for producing the same.