Layered Depth Filter Structure for Submicron Filtration Flow
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Solution Overview
Problem
Existing depth filters struggle with high-pressure filtration, low liquid permeability, and poor capture performance for submicron-sized particles and gels, leading to filtration precision issues and complex process management.
Innovation Solution
A depth filter design comprising an outer layer with decreasing fiber diameter, a pre-filtration layer with varying fiber diameters, and a precision filtration layer with ultrafine fibers, all thermally bonded for enhanced filtration absoluteness, gel removal, and liquid permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the fiber diameter of the precision filtration layer is reduced to capture finer particles, then filtration precision is improved, but liquid permeability deteriorates and filtration pressure increases
Solution Approach 1:
The filter medium is divided into multiple layers with different fiber diameters: a pre-filtration layer with larger fibers (1-10 μm) and a precision filtration layer with finer fibers (0.1-1 μm). This segmentation allows each layer to perform its specific function - the pre-filtration layer captures larger particles and the precision layer captures finer particles - while maintaining overall liquid permeability through the optimized structure.
Solution Approach 2:
Different regions of the filter medium have different fiber diameters tailored to their specific filtration functions. The pre-filtration layer uses coarser fibers for capturing larger particles, while the precision filtration layer uses finer fibers for capturing submicron particles. This local differentiation of fiber properties optimizes both filtration precision and liquid permeability throughout the filter structure.
2Manufacturing precision
If the basis weight of the filter medium is increased to improve capture performance, then filtration precision is improved, but liquid permeability deteriorates and pressure loss increases
Solution Approach 1:
The filter is segmented into layers with different basis weights and fiber diameters. The pre-filtration layer has higher basis weight for capturing larger particles, while the precision filtration layer has optimized basis weight for capturing finer particles. This segmentation prevents any single layer from having excessively high basis weight that would cause overall pressure loss.
Solution Approach 2:
Each layer of the filter medium has locally optimized basis weight and fiber diameter properties matched to its specific capture function. The pre-filtration layer uses higher basis weight for structural support and coarse particle capture, while the precision layer uses appropriately optimized basis weight to balance fine particle capture with liquid flow, preventing excessive pressure loss.
3Manufacturing precision
If ultrafine fibers are used to capture submicron particles, then filtration precision is improved, but the filter medium becomes hydrophobic and water passage becomes difficult
Solution Approach 1:
The chemical composition and surface properties of the ultrafine fibers in the precision filtration layer are modified to change the hydrophobicity parameter. By adjusting the resin type, fiber surface treatment, or compositional parameters, the filter medium transitions from highly hydrophobic to more hydrophilic, enabling easier water passage while maintaining the submicron filtration capability of the ultrafine fiber structure.
4Manufacturing precision
If the filter medium is thickened to improve capture performance, then filtration precision is improved, but liquid permeability deteriorates and push-out phenomenon occurs
Solution Approach 1:
The filter medium is segmented into functional layers with different thicknesses and fiber diameters. The pre-filtration layer provides structural support and captures larger particles, while the precision filtration layer with ultrafine fibers provides fine particle capture. This segmentation allows the overall filter to achieve high precision without requiring excessive thickness that would cause push-out phenomena.
Solution Approach 2:
The filter medium combines different materials with complementary properties: the pre-filtration layer uses coarser fibers for structural support and coarse particle capture, while the precision filtration layer uses ultrafine fibers for fine particle capture. This composite structure achieves high filtration precision through material composition rather than merely increasing thickness, preventing push-out phenomena.
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 design achieves high-precision filtration of submicron particles with improved liquid permeability, stability under pressure, and simplified process management, reducing the risk of particle leakage and maintaining filtration efficiency over time.
Implementation Method 1
an outer layer in which an outer layer nonwoven fabric including a high-melting-point resin and a low-melting-point resin is wound in multiple layers, and wound nonwoven fabrics are thermally bonded by the low-melting-point resin
Implementation Method 2
a filter medium of nonwoven fabric composed of melt blow ultrafine fibers does not employ surface filtration with high filtration absoluteness like precision membranes with uniform pore diameter, but employs a depth filtration mechanism that captures fine particles by the thickness of the filter medium
Implementation Method 3
filtration is performed by wetting the filter medium while removing air contained in the filter medium through pressure wetting
Data Source
AI summary
Provided is a depth filter which has the absolute property of filtration and the removing performance of gel even for particles to be removed having a reduced particle diameter, and is excellent in liquid permeability. This depth filter comprises an outer layer, a pre-filtration layer, and a precision filtration layer arranged in this order with respect to the filtration direction. The outer layer is formed by winding an outer layer nonwoven fabric containing a high-melting-point resin and a low-melting-point resin multiply, the nonwoven fabrics to be wound are thermally bonded by the low-melting-point resin, and the average fiber diameter is continuously reduced with respect to the filtration direction. The precision filtration layer is a layer in which a nonwoven fabric for the precision filtration layer having an average fiber diameter of less than 300 nm is wound multiply. The pre-filtration layer is a layer in which a nonwoven fabric for the precision filtration layer having an average fiber diameter of 300 nm or more, a nonwoven fabric for a pre-filtration layer having an average fiber diameter of less than 1000 nm is wound multiply, and an average fiber diameter is constant or gradually decreases with respect to the filtration direction.