Electret and filter using the same
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Solution Overview
Problem
Existing electret filters containing polyolefin resin and magnesium element exhibit suboptimal filtering performance, particularly for particles with aerodynamic equivalent diameters of 0.1 to 1.0 μm.
Innovation Solution
An electret comprising polyolefin resin and a nitrogen-containing compound, with controlled magnesium content (5 to 100 ppm) and a QF value ≥1.00 mmAq−1, is produced using a meltblown method, incorporating a fatty acid magnesium salt and a hindered-amine-based compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin resin and magnesium element are used in electret filter, then cost and basic filtration are maintained, but filtering performance for particles of 0.1 to 1.0 μm deteriorates
Solution Approach 1:
The patent optimizes the magnesium element content parameter to a specific range (5-100 ppm) to resolve the contradiction. By precisely controlling the magnesium content within this narrow range, the electret filter achieves high particle collection efficiency for 0.1 to 1.0 μm particles while maintaining cost-effectiveness and basic filtration performance. This parameter optimization eliminates the suboptimal filtering performance associated with conventional electret filters containing polyolefin resin and magnesium element.
2Reliability
If electret filter is designed for high particle collection efficiency, then ventilation resistance increases, but airflow performance deteriorates
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: magnesium element content (5-100 ppm), nitrogen-containing compound content (0.1-5 parts by mass per 100 parts polyolefin resin), and QF value (≥1.00 mmAq−1). This multi-parameter optimization achieves high particle collection efficiency while maintaining low ventilation resistance, resolving the contradiction between filtration performance and airflow performance.
Solution Approach 2:
The electret filter uses a composite material system combining polyolefin resin, nitrogen-containing compound, and controlled magnesium element content. This composite structure enables simultaneous achievement of high particle collection efficiency and low ventilation resistance, as the synergistic interaction between components optimizes both filtration and airflow 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 electret achieves enhanced filtering performance with high QF values, low particle penetration, and suitable ventilation resistance, making it suitable for air purifiers and air conditioning filters.
Implementation Method 1
a method in which electric charge is applied to the filter... Particularly in the latter method, energy from an external power supply or the like is unnecessary, and a filter containing such an insulating material is thus widely used as an electret filter
Implementation Method 2
A method using electric attraction in combination in order to enhance particle collecting efficiency of a filter for particles having the aerodynamic equivalent diameters of about 0.1 to 1.0 μm
Implementation Method 3
an electret is preferably formed by applying an electrostatic charge to a fibrous product in a method (liquid contact charging method) in which liquid is brought into contact or collision with the fibrous product
Implementation Method 4
particles are collected on fibers by mechanical collecting mechanisms such as contact-adhesion, diffusion, and inertial impaction
Implementation Method 5
particles are collected on fibers by mechanical collecting mechanisms such as contact-adhesion, diffusion, and inertial impaction
Implementation Method 6
particles are collected on fibers by mechanical collecting mechanisms such as contact-adhesion, diffusion, and inertial impaction
Data Source
AI summary
It is provided that an electret having excellent filtering performance and a filter using the electret even in a case where polyolefin resin and magnesium element are contained. An electret comprising a polyolefin resin and a nitrogen-containing compound, wherein 0.1 to 5 parts by mass of the nitrogen-containing compound is contained to 100 parts by mass of the polyolefin resin, a proportion of a magnesium element contained in the electret is 5 to 100 ppm, and a QF value represented by the following formula is not less than 1.00 mmAq−1 when particles having particle diameters of 0.3 to 0.5 μm are to be collected.QF [mmAq−1]=−[ln(particle penetration(%)/100)]/[ventilation resistance (mmAq)]