Porous Polymeric Membrane Single-Step Coagulation
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Solution Overview
Problem
Current filter membrane manufacturing methods require multiple steps and materials to achieve a double-tight membrane structure, increasing costs and complexity, while existing techniques often result in non-integral multi-layer membranes with asymmetric pore distributions.
Innovation Solution
A single-step method to form a porous polymeric membrane with two tight regions and an open region by extruding a polymer solution through a die and simultaneously exposing both sides to a coagulation condition, such as temperature or nonsolvent, to create a uniform coagulated film with varying pore sizes across the thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-layer membrane stacking is used to achieve double-tight structure, then retention capability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple membrane layers into a single integral membrane structure formed by simultaneous coagulation of polymer solution at both surfaces. This combining approach achieves the double-tight structure in one manufacturing step rather than stacking separate layers, thereby improving retention capability while reducing manufacturing complexity and cost.
Solution Approach 2:
The membrane is segmented into distinct regions (first tight region, second tight region, and intermediate open region) with different pore sizes within a single integral structure. This segmentation allows different portions of the membrane to perform different filtration functions while being manufactured as one piece, achieving high retention without multi-layer stacking.
2Reliability
If multiple separate membranes are stacked to form multi-layer membrane, then filtration performance is improved, but manufacturing cost and process steps increase
Solution Approach 1:
Multiple membrane functions are merged into a single integral membrane by simultaneously coagulating polymer solution at both surfaces to create tight regions. This eliminates the need to manufacture and assemble separate membrane layers, reducing manufacturing cost and process steps while maintaining enhanced filtration performance.
Solution Approach 2:
The patent changes the coagulation parameters (temperature, nonsolvent exposure) during membrane formation to create regions with different pore sizes within a single membrane. By controlling these parameters during the forming process, the membrane achieves multi-layer-like filtration performance without the associated manufacturing complexity and cost.
3Productivity
If asymmetric membrane structure is used with different pore sizes at each surface, then filtration efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The membrane exhibits local quality variations with different pore sizes in different regions (tight regions at surfaces, open region in intermediate portion). This local differentiation of pore structure allows the membrane to achieve high filtration efficiency by having surface regions optimized for particle rejection while the intermediate region maintains structural integrity and flow.
Solution Approach 2:
The patent employs asymmetric membrane structure where the first and second tight regions have different pore sizes from the intermediate open region. This asymmetry is achieved through controlled coagulation processes that create surface-skinned structures with smaller pores at the boundaries and larger pores in the center, improving filtration efficiency without requiring excessive manufacturing precision.
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 approach enables the production of a single, integral membrane with enhanced retention capabilities and cost-effectiveness, surpassing traditional multi-layer membranes in filtration efficiency and mechanical properties.
Implementation Method 1
exposing both sides of the extruded film to a condition that will cause coagulation of the polymer on both sides of the film
Implementation Method 2
causing the polymer to coagulate within the film by simultaneously exposing both of two opposed surfaces of the film to a condition that will cause coagulation of the polymer
Data Source
AI summary
Described are porous polymeric membranes that include two opposing sides and that have a variable pore structure through a thickness of the membrane; filter components and filters that include this type of porous polymeric membrane; methods of making the membranes, filter components, and filters; and methods of using the polymeric filter membrane, filter component, or filter.