ePTFE Filter Media with Carded Scrim for Low Pressure Drop
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Solution Overview
Problem
Existing filter media with expanded polytetrafluoroethylene (ePTFE) face challenges in manufacturing, such as damage during processing and unsatisfactory characteristics like pleatability and stiffness, and often result in high pressure drops, making them unsuitable for non-industrial applications.
Innovation Solution
A filter media is developed with a carded pleatable scrim layer, where fibers are aligned through combing or brushing, and bonded with a porous ePTFE film using a powdered polymeric material, reducing pressure drop and enhancing self-supporting properties, while maintaining efficiency between 70% and 90%, specifically 80%, and achieving a cost advantage over spun-laid fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expanded polytetrafluoroethylene (ePTFE) is incorporated within the filter media to achieve high efficiency rating, then filtration efficiency is improved, but pressure drop increases
Solution Approach 1:
The patent uses a composite structure combining ePTFE particles with a scrim support material. The ePTFE particles provide filtration efficiency while the scrim support structure maintains open porosity and prevents particle compaction, thereby reducing pressure drop compared to traditional dense ePTFE filters.
Solution Approach 2:
The filter media employs a highly porous structure where ePTFE particles are distributed within a three-dimensional scrim network. This porous arrangement allows efficient particle capture while maintaining high airflow capacity, reducing the pressure drop penalty typically associated with high-efficiency filters.
2Strength
If scrim or support materials are used in making ePTFE containing filter media, then structural support is improved, but manufacturing process steps are restricted and pleatability deteriorates
Solution Approach 1:
The patent modifies the physical and chemical parameters of the scrim material, specifically using a carded non-woven structure with controlled fiber orientation and bonding characteristics. This parameter optimization enables the scrim to provide structural support while maintaining pleatability and flexibility during manufacturing.
Solution Approach 2:
The scrim support material is designed with non-uniform fiber distribution and localized bonding characteristics, creating regions of varying density and flexibility. This local quality variation allows the scrim to provide where needed structural support while maintaining overall pleatability for filter formation.
3Device complexity
If traditional filter media are used, then manufacturing simplicity is maintained, but pleatability and stiffness characteristics are unsatisfactory
Solution Approach 1:
The filter media is designed with dynamic pleating capability, where the carded scrim structure allows the filter to be formed into pleats during manufacturing and then maintains its shape through controlled bonding. This dynamic design enables simple manufacturing processes while achieving excellent pleatability and stiffness characteristics.
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 results in a filter media with up to 50% less pressure drop compared to traditional filters of similar efficiency, providing a cost-effective and efficient filtration solution for non-industrial applications with improved pleatability and stiffness.
Implementation Method 1
a filter media is provided having a carded pleatable scrim layer bonded to a porous expanded polytetrafluoroethylene (ePTFE) film
Implementation Method 2
bonded with a porous ePTFE film using a powdered polymeric material
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A filter media product and method of making the same wherein the filter media is pleatable and has at least one support scrim comprised of a melt bonded non-woven material or a fuse bonded non-woven material bonded to a layer of expanded polytetrafluoroethylene. The filter media may have a single support scrim with one or more layers and optionally may have a support scrim on both an upstream and downstream surface where both or neither support scrim is multilayered. The filter media may have an efficiency greater than, equal to, or less than HEPA.