Separation Membrane Edge Thickness Layout to Prevent Curling
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Solution Overview
Problem
Separation membranes experience curling issues during production due to differential thermal shrinkage between the base and the separation layer, affecting their operability and stability.
Innovation Solution
A separation membrane design featuring a predetermined thickness portion with thinner portions on the ends and separation-layer-lacking areas, where the base is exposed, is applied to prevent curling by controlling the polymer solution application and solidification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separation layer is formed uniformly over the entire surface of the base including both widthwise ends, then the separation function is improved, but curling occurs at both widthwise end portions due to differential shrinkage
Solution Approach 1:
The separation layer is designed with different thickness characteristics at different locations: a predetermined thickness portion at the central part and thinner portions at both widthwise end portions. This local variation in thickness prevents differential shrinkage at the ends while maintaining adequate separation function in the central region.
Solution Approach 2:
The separation layer is segmented into distinct thickness zones: a central predetermined thickness portion and end thinner portions. This segmentation allows different regions to have different shrinkage characteristics, preventing overall curling while maintaining separation functionality.
2Shape
If the separation layer is made thinner at the widthwise ends to prevent curling, then the curling phenomenon is suppressed, but the separation function at the ends is reduced
Solution Approach 1:
The separation layer is made thinner than the full predetermined thickness only at the widthwise end portions, while maintaining the full thickness at the central part. This partial reduction in thickness is sufficient to prevent curling while preserving adequate separation function where it is most needed.
3Area of stationary object
If the polymer solution is applied to the entire base surface, then complete separation layer coverage is achieved, but differential shrinkage between base and separation layer causes curling
Solution Approach 1:
The polymer solution application is localized to create different thickness zones: full coverage at the central part and reduced coverage at the widthwise ends. This local variation in application density creates the desired thickness profile that prevents curling.
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 design effectively suppresses curling, stabilizing the production process and ensuring a curl-free separation membrane, facilitating the production of separation elements.
Implementation Method 1
the base, which has been through the polymer solution application step, in a solidifying step
Implementation Method 2
In the solidifying step and the water-washing step, shrinkage occurs in both the base 121 and the polymer solution coating film 122
Data Source
AI summary
Disclosed is a separation membrane comprising—an elongated substrate having fluid permeability and a separation layer formed at the surface of said substrate—wherein the aforementioned separation layer comprises a predetermined thickness section having a predetermined thickness and thin sections each positioned on the outside of both edges in the widthwise direction of said predetermined thickness portion and having a thinner thickness than the aforementioned predetermined thickness, and there is a separation-layer-lacking section, at which only the aforementioned substrate is present and the aforementioned separation layer is absent, between the outside edges in the widthwise direction of each of said thin sections and the outer edges in the widthwise direction of the aforementioned substrate. The separation membrane can be produced by using coating bar having a protrusion on both the left and right ends of the surface that contacts a macromolecule solution for forming the separation layer.