Pleated Nanoweb Filter Media with Scrim Support
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Solution Overview
Problem
Existing filter media with pleated melt-blown structures face issues with high flow resistance and decreased filtration efficiency due to thick layers and loss of electrostatic charge over time.
Innovation Solution
A filter medium with a pleated structure comprising a nanoweb layer and a scrim, where the nanoweb layer has fibers less than 1 micron in diameter and 50 microns in thickness, and a scrim made from spunbond, dry-laid, or melt-blown fibers, with a media thickness-to-pleat-spacing ratio of less than 0.15, enhancing airflow and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a melt-blown layer is used to achieve acceptable initial filtration efficiency, then filtration efficiency is improved, but flow resistance increases due to thick layer (0.2-0.4 mm) and tangential flow patterns
Solution Approach 1:
The patent changes the fiber diameter parameter from conventional 1-5 microns to ultrafine 0.1-1 micron, and reduces layer thickness from 0.2-0.4 mm to less than 50 microns. This parameter transformation maintains filtration efficiency while dramatically reducing flow resistance and improving airflow patterns through the media.
Solution Approach 2:
The patent combines a nanoweb layer (0.1-1 micron fibers) with a scrim support layer to create a composite filter medium. This composite structure provides both the fine filtration capability of nanofibers and the mechanical support needed to maintain pleat geometry, achieving acceptable initial filtration efficiency with reduced resistance.
2Reliability
If the total media thickness is increased to improve filtration capacity, then filtration efficiency is improved, but flow resistance increases and pleat spacing becomes more difficult to manage
Solution Approach 1:
The patent transforms the media thickness parameter from greater than 0.6 mm to less than 0.05 mm (50 microns). This thin-media approach maintains filtration efficiency through ultrafine fibers while enabling better pleat spacing control and reducing the complexity of achieving uniform pleats throughout the media.
3Reliability
If electrostatically charged microfiber web is used to achieve initial filtration efficiency, then filtration efficiency is improved, but electrostatic charge is lost over time due to heat, humidity, and dust accumulation
Solution Approach 1:
The patent changes from charged microfiber webs to uncharged nanoweb structures with 0.1-1 micron fibers. This parameter change eliminates the electrostatic charge loss problem while maintaining filtration efficiency through the physical structure and size of the nanofibers rather than electrostatic forces.
Solution Approach 2:
The patent adopts a disposable filter media approach where the entire nanoweb-scrim structure is replaced after a single use. This eliminates the need to maintain electrostatic charge over time, as the media is discarded after achieving its filtration function, avoiding the degradation issues of charged media.
4Area of stationary object
If a thicker melt-blown layer is used to increase surface area for fluid impact, then filtration capacity is improved, but flow pattern becomes less perpendicular and resistance increases
Solution Approach 1:
The patent changes the layer thickness parameter from 0.2-0.4 mm to less than 50 microns, and increases the fiber density through 0.1-1 micron fibers. This creates a thinner but denser media that maintains adequate surface area for fluid impact while preserving perpendicular flow patterns and reducing resistance.
Data Source
AI summary
A filter including a filter medium with a pleated structure. The medium includes a nanoweb layer and a scrim, wherein the nanoweb layer contains fibers with a number average diameter less than 1 micron and layer thickness less than 50 microns. The ratio of total medium thickness-to-pleat spacing is less than 0.15 and the nanoweb layer has a basis weight of more than about 0.6 gsm. The nonwoven scrim can be a spunbond web, a dry-laid web, a wet-laid web, a cellulose fiber web, a melt blown web and a glass fiber web.