High-Efficiency PTFE Filter Media with Uniform Scrim Support
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Solution Overview
Problem
There is a need for improved high efficiency particulate air (HEPA) filtration media, media packs, and filter elements that can effectively remove small particulates, including particles from engine combustion, dust, microbes, and viruses, while maintaining structural integrity and efficiency.
Innovation Solution
A filtration media pack with multiple layers of single facer media, comprising a fluted sheet and a facing sheet with a polytetrafluoroethylene (PTFE) layer supported by a polymeric scrim layer, where the scrim layer is designed to have uniform fiber distribution and controlled peak heights to provide enhanced support and filtration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin PTFE layer is used for high filtration efficiency, then filtration efficiency improves, but structural integrity and support deteriorate
Solution Approach 1:
The patent combines PTFE (polytetrafluoroethylene) with a polymeric scrim layer to create a composite filter media structure. The PTFE layer provides high filtration efficiency for particles down to 0.3 microns, while the polymeric scrim layer provides structural support and mechanical strength. This composite structure allows the thin PTFE layer (typically 0.1-0.5 mils) to maintain its filtration performance without compromising structural integrity.
Solution Approach 2:
The filter media is designed with different layers having different local properties: the PTFE layer is optimized for filtration performance with specific pore sizes and distributions, while the polymeric scrim layer is optimized for mechanical support with higher tensile strength and structural stability. Each layer performs its specific function locally, allowing the overall structure to achieve both high filtration efficiency and structural integrity.
2Strength
If the polymeric scrim layer has high fiber peak height for support, then structural support improves, but uniformity of PTFE layer support deteriorates
Solution Approach 1:
The patent specifies precise parameter ranges for the polymeric scrim layer, including fiber diameter (typically 10-50 microns), basis weight (0.5-2.0 ounces per square yard), and maximum peak height (controlled to ensure uniformity). By controlling these parameters within specific ranges, the scrim layer provides consistent support across the entire filter media surface while maintaining adequate structural strength.
Solution Approach 2:
The polymeric scrim layer is designed with uniform fiber distribution and consistent structural properties across the filter media surface. This homogeneity ensures that the PTFE layer receives uniform support throughout, preventing localized variations in filtration performance. The scrim layer's uniform structure is achieved through controlled manufacturing processes that maintain consistent fiber spacing, density, and bonding characteristics.
3Reliability
If multiple layers of single facer media are used, then filtration efficiency improves, but device complexity increases
Solution Approach 1:
The filter media is segmented into distinct functional layers: a fluted sheet layer providing structural rigidity and flow distribution, a PTFE layer providing high-efficiency particle filtration, and a polymeric scrim layer providing mechanical support. Each layer is independently optimized for its specific function, allowing the multi-layer structure to achieve superior filtration performance while maintaining manageable complexity through clear functional differentiation.
Solution Approach 2:
The single facer media structure integrates multiple functions within a unified design: the fluted sheet provides both structural support and flow distribution, the PTFE layer provides filtration while maintaining breathability, and the scrim layer provides mechanical strength while allowing fluid passage. This multi-functionality reduces the need for separate components, thereby managing overall device complexity.
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 high filtration efficiency of 99.97% for 3 micron particles across various flow rates and velocities, with improved structural integrity and air permeability, enhancing the performance of HEPA filtration systems.
Implementation Method 1
a polytetrafluoroethylene (PTFE) layer supported by a polymeric scrim layer... fluid passing into one of the first face or the second face of the media pack and out the other of the first face or the second face of the media pack passes through media to provide filtration of the fluid
Data Source
AI summary
Filtration media packs, filter elements, and media are disclosed, including media packs having a plurality of layers of single facer media wherein the layers of single facer media include a fluted sheet, a facing sheet, and a plurality of flutes extending between the fluted sheet and the facing sheet, with the fluted sheet and facing sheet formed of multi-layer media can include a polytetrafluoroethylene (PTFE) layer supported by a polymeric scrim layer.