Fine Fiber Filter Media Extrusion Dwell Time Control
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Solution Overview
Problem
Current polymer fiber extrusion processes often result in fiber webs with high levels of polymer degradation, leading to reduced performance and increased basis weight due to prolonged exposure to high temperatures and pressures, which affects filtration efficiency and structural characteristics.
Innovation Solution
The process involves controlling the dwell time and throughput of polymeric material in the extrusion system by reducing the processing space volume and adjusting parameters such as temperature and air flow to minimize polymer degradation, forming fine fibers with diameters between 0.1 and 1.5 microns and achieving low surface densities of particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the polymeric material is exposed to high temperatures and pressures for prolonged periods during extrusion, then the polymer is thoroughly processed and extruded, but polymer degradation occurs leading to increased basis weight and reduced filtration efficiency
Solution Approach 1:
The patent applies the 'Skipping (Rushing through)' principle by significantly reducing the dwell time of polymeric material in the extrusion system. The processing space is designed to allow the polymer to pass through quickly at high temperatures and pressures without prolonged exposure, thereby preventing degradation while still achieving thorough processing and extrusion of fine fibers.
2Manufacturing precision
If fine fibers with smaller diameters are produced, then filtration efficiency and surface area are improved, but the basis weight increases due to polymer degradation
Solution Approach 1:
By rushing the polymeric material through the extrusion system with reduced dwell time, the patent prevents polymer degradation that would otherwise increase basis weight. This allows production of fine fibers with precise diameter control (0.1-1.5 microns) while maintaining lower basis weight through efficient, rapid processing.
Solution Approach 2:
The patent changes critical processing parameters including temperature, pressure, and especially dwell time. By optimizing these parameters and reducing the time the polymer spends in the high-temperature extrusion zone, the process produces fine fibers with controlled diameters while minimizing degradation-related weight increase.
3Loss of substance
If the processing space volume is reduced to decrease dwell time, then polymer degradation is minimized, but the extrusion system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the extrusion system into distinct functional zones: a mixing zone for blending polymeric material with additives, and a separate extrusion zone for fiber formation. This segmentation allows the processing space to be compact while maintaining functional efficiency, reducing dwell time without overly complicating the overall system design.
Solution Approach 2:
By changing the parameters of the extrusion system—specifically reducing processing space volume and optimizing the ratio of mixing to extrusion zones—the patent achieves reduced dwell time and minimal polymer degradation while keeping the system design manageable through parameter optimization rather than radical structural changes.
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
This approach results in fiber webs with improved structural and performance characteristics, including reduced air permeability, increased surface area, and lower basis weight, enhancing filtration efficiency while minimizing polymer degradation.
Implementation Method 1
In a meltblowing process, a fiber web may be formed by extruding a polymeric material through a die and then attenuating the resulting filaments with a heated, high-velocity air stream
Implementation Method 2
a heated, high-velocity air stream
Data Source
AI summary
Fine fiber products including fiber webs, as well as related assemblies, systems and methods, are described. In some embodiments, fiber webs described herein may include fine fibers and relatively low amounts of degraded polymer formed during a fiber extrusion process. The fiber webs may be used for filter media applications.