Electret Microfiber Web Composition for Long-Lasting Filtration Charge
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Solution Overview
Problem
Existing electret webs for aerosol filtration lack improved properties for efficient charge retention and ease of charging using various mechanisms.
Innovation Solution
Incorporating ester-substituted and/or amide-substituted trianilino triazine materials as charge additives in thermoplastic resin blends for non-woven microfiber webs, allowing for enhanced charge retention and ease of charging through methods like DC corona discharge or hydrocharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional charging methods (DC corona discharge, hydrocharging) are used on standard thermoplastic microfiber webs, then the webs can be charged, but the charge retention capability is relatively short and filtration performance degrades over time
Solution Approach 1:
The patent modifies the chemical composition parameters of the thermoplastic resin by incorporating specific additives (ester-substituted and amide-substituted trianilino triazine materials) that alter the material's electrical properties. This enables the resin to retain electret charge much longer than conventional thermoplastics, maintaining filtration performance over extended periods.
Solution Approach 2:
The invention creates a composite material system by blending charge-enhancing additives into the thermoplastic resin matrix. This composite approach combines the processability of thermoplastics with the long-term charge retention properties of electret materials, achieving both ease of manufacture and sustained performance.
2Duration of action of stationary object
If charge-enhancing additives are incorporated into thermoplastic resin, then charge retention is improved, but the complexity of material formulation increases
Solution Approach 1:
The patent specifies particular chemical structure parameters for the charge-enhancing additives (ester-substituted and amide-substituted trianilino triazine materials), which standardize the formulation process. By defining specific chemical families rather than allowing arbitrary additives, the invention manages complexity while achieving improved charge retention.
3Ease of manufacture
If existing thermoplastic materials are used without charge additives, then the material is easy to process and manufacture, but the electret charge retention is insufficient for long-term filtration efficiency
Solution Approach 1:
The invention maintains the base thermoplastic resin as the continuous phase, preserving its excellent processability and ease of manufacture. The charge-enhancing additives are dispersed within this matrix in controlled amounts, providing long-term charge retention without significantly complicating the manufacturing process. The composite structure allows standard melt-blowing and processing techniques to be used.
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 electret webs exhibit improved filtration performance with long charge retention capability and ease of charging, maintaining high filtration efficiency even after accelerated aging tests.
Implementation Method 1
An electret is a dielectric material exhibiting a quasi-permanent electrical charge. Electrets are useful in a variety of devices including, e.g. cling films, air filters, filtering facepieces, and respirators
Implementation Method 2
Other methods include, for example, charging the fibers after the web is formed, by means of a DC corona discharge
Implementation Method 3
Recently, a method in which jets of water or a stream of water droplets impinge on a non-woven web at a pressure sufficient to provide filtration enhancing electret charge has been described (hydrocharging)
Implementation Method 4
These charge enhancing additives provide electret webs that are easy to charge by a variety of different charging mechanisms such as DC corona discharge, hydrocharging or a combination thereof. In addition, the electret webs containing charge-enhancing additives have relatively long charge retention capability
Data Source
AI summary
Electret webs are presented which include a blend of a thermoplastic resin and a charge additive. The charge additives include ester-substituted and amide-substituted trianilino triazine materials. The webs prepared from the blends may be in the form of films or non-woven fibrous webs. Non-woven microfiber webs are useful as filtration media.