Separation Membrane Edge Coating Layout to Prevent Curling
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Solution Overview
Problem
Separation membranes often curl during production due to differences in chemical composition and thermal shrinkage between the base and the separation layer, leading to operational instability and reduced efficiency.
Innovation Solution
A separation membrane design featuring a first separation layer with a predetermined thickness portion and a thinner portion at the ends, along with a separation-layer-lacking portion, where the base is exposed, to minimize curling by reducing thermal shrinkage forces, and a method involving a bar coater with protruded portions to apply the polymer solution, ensuring a curl-free membrane production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separation layer is formed directly over the entire surface of the base including widthwise ends, then the separation function is improved, but curling occurs due to shrinkage difference
Solution Approach 1:
The separation layer is designed with different thickness characteristics at different locations: a predetermined thickness in the central region and a thinner portion at the widthwise end portions. This local variation in thickness reduces the shrinkage difference between the base and separation layer at the ends, preventing curling while maintaining separation function in the central region.
Solution Approach 2:
The separation layer is effectively segmented into different thickness zones: a central region with predetermined thickness for separation function and end regions with reduced thickness to minimize shrinkage-induced curling. This segmentation allows each region to serve its specific purpose without causing overall deformation.
2Ease of manufacture
If the separation layer has uniform thickness across the width, then manufacturing is simplified, but curling reduces operability
Solution Approach 1:
Instead of uniform thickness, the separation layer implements local quality variation with a thinner portion at the widthwise ends. This design maintains relatively simple manufacturing processes while significantly improving operability by preventing curling that would otherwise occur during production and handling.
3Area of stationary object
If the polymer solution coating film is applied over the entire base surface, then coverage is maximized, but shrinkage difference causes curling
Solution Approach 1:
The polymer solution coating is applied with local quality variation: full coverage in the central region for maximum separation function, and reduced coverage or thinner coating at the widthwise end portions to minimize shrinkage difference and prevent curling, thus resolving the contradiction between coverage area and shape stability.
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 effectively prevents curling, stabilizes the production process, and facilitates the creation of curl-free separation membranes, enhancing operational stability and membrane performance.
Implementation Method 1
In the solidifying step and the water-washing step, shrinkage occurs in both the base 121 and the polymer solution coating film 122. In respect of the occurrence of shrinkage, the shrinkage of the polymer solution coating film 122 is greater than that of the base 121
Data Source
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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.