Cellulose Acetate Hollow Filter Tow for Low EPD and Strength
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Solution Overview
Problem
Existing cellulose acetate filters face challenges in achieving desired draw resistance, strength, and hardness while maintaining low encapsulated pressure drop (EPD) for smaller-diameter smoking articles and increased filter efficacy, particularly when using low or medium total denier tow bands.
Innovation Solution
The use of high total denier cellulose acetate tow, ranging from 3 to 6 denier per filament and 50,000 to 100,000 total denier, in forming non-wrapped or hollow filter rods, which maintains low EPD and enhances filtering efficacy while ensuring strength and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low denier per filament and medium total denier tow bands are used, then filtering efficacy is improved through high surface area, but encapsulated pressure drop increases and draw characteristics deteriorate
Solution Approach 1:
The patent changes the denier parameters by using high total denier (≥40,000) tow bands with moderate denier per filament (3-12 dpf), which fundamentally alters the filter's mass and surface area characteristics to achieve both high filtering efficacy and low encapsulated pressure drop simultaneously
Solution Approach 2:
The patent creates a composite filter structure combining high total denier cellulose acetate tow with specific additives (such as plasticizers, binders, or functional particles) to achieve the desired balance between filtering performance, pressure drop, and mechanical properties
2Stress or pressure
If high denier per filament and low total denier tow bands are used, then encapsulated pressure drop is reduced, but filter strength and hardness are compromised
Solution Approach 1:
The patent reverses the conventional approach by using high total denier (≥40,000) tow bands, which provides sufficient mass for strength while maintaining moderate denier per filament to keep encapsulated pressure drop low, thereby resolving the contradiction between pressure drop and strength
3Reliability
If particles that actively remove smoke components are included, then filtering efficacy is improved, but encapsulated pressure drop increases and fiber strength is compromised
Solution Approach 1:
The patent optimizes the concentration and type of functional particles (such as carbon, metal oxides, or other smoke-removing additives) incorporated into the high total denier tow band, maintaining sufficient filtering efficacy while preserving fiber strength and avoiding excessive encapsulated pressure drop
Solution Approach 2:
The patent creates a optimized composite material system combining high total denier cellulose acetate tow with specific functional particles and binders, where the composite structure allows smoke component removal while maintaining mechanical integrity
Data Source
Figure 1
AI summary
Disclosed are cellulose acetate tows, bales, and filter rods having at least 3 denier per filament and at least 50,000 total denier, or at least 6 denier per filament and at least 40,000 total denier, for use as hollow filters, non-wrapped filters, or combinations thereof, in smoking devices and aerosol-generating devices, such as an electrically heated cigarette. The cellulose acetate tow may comprise at least 3-6 denier per filament and may have a total denier of at least 50,000 to 100,000. The cellulose acetate tow comprises at least 6-12 denier per filament and may have a total denier of at least 40,000 to 90,000. The hollow filter may comprise a non-wrapped cellulose acetate hollow filter.