Centrifugal Melt Spun Nanofibrous Web for Respiratory Filtration
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Solution Overview
Problem
Conventional face masks and respirators with nanofibrous media face challenges in providing adequate protection against inhaled aerosols due to high resistance, which affects breathability and comfort, while being costly and inefficient in filtering tiny particles.
Innovation Solution
A nanofibrous web comprising at least 70% nanofibers, 5%-25% microfibers, and 0%-5% coarse fibers, with a number average diameter less than 1000 nm and median diameter less than 500 nm, produced through a centrifugal melt spinning process, forming a single layer with an electrostatic charge and low apparent density, enhancing filtration efficiency and breathability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanofibrous media with smaller pore size is used to improve filtration efficiency, then particle trapping capability is improved, but resistance or pressure drop increases making masks less breathable
Solution Approach 1:
The patent applies parameter changes by optimizing the fiber diameter distribution parameters, specifically maintaining a number average diameter of 0.5-2.0 μm and median diameter of 0.3-1.5 μm. This parameter optimization creates an balance between pore size for filtration and overall structure for breathability, resolving the contradiction between filtration efficiency and breathability
Solution Approach 2:
The patent uses composite materials by combining nanofibers (≥70% by number) with microfibers (5-25% by number) and coarse fibers (0-5% by number). This multi-scale fiber composite creates a hierarchical structure where nanofibers provide fine particle filtration while larger fibers maintain structural integrity and breathability, resolving the filtration-breathability contradiction
2Reliability
If conventional nanofiber media is used to improve particle filtration, then filtration efficiency is improved, but cost increases due to electrospinning or melt-blown processes
Solution Approach 1:
The patent employs disposable, single-use nonwoven masks with integrated nanofiber filtration layers that are economically priced for consumer use. The masks are designed as disposable products that combine effective nanofiber filtration with cost-effective manufacturing, making high-effiltration masks accessible to the general public rather than just industrial applications
Solution Approach 2:
The patent merges the filtration function and structural support function into a single integrated nonwoven layer. By combining nanofibers, microfibers, and coarse fibers in one homogeneous structure, it eliminates the need for separate substrate and coating layers, reducing manufacturing steps and costs while maintaining filtration efficiency
3Reliability
If nanofibers are used as coating on separate substrate to improve filtration, then particle trapping is improved, but device complexity increases due to multiple layers
Solution Approach 1:
The patent merges multiple functions into a single nonwoven layer that simultaneously provides filtration, structural support, and breathability. The integrated structure combines nanofibers, microfibers, and coarse fibers in one layer, eliminating the need for separate substrate and coating layers, thus reducing device complexity while maintaining filtration efficiency
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 nanofibrous web effectively traps tiny particles, provides desirable breathability, and user comfort, while being cost-effective for use in face masks and respirators, with improved filtration efficiency and reduced pressure drop.
Implementation Method 1
attenuating the discharged discrete filaments in the stretching zone by centrifugal force to form continuous fibers
Implementation Method 2
forming a single layer with an electrostatic charge, enhancing filtration efficiency
Data Source
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AI summary
The present disclosure is directed toward an improved nanofibrous electret filtration media of which the stand-alone electret nanofibrous web comprises a single source randomly intermingled fiber network that yields high breathability due to the high porosity and improved filtration efficiency for use as improved filtration media for respiratory devices and face masks.