Layered Air Filter Medium for Fine-Particle Clogging Control

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Solution Overview

Problem

Existing air filter media using porous fluorine resin membranes experience increased pressure drop due to clogging from fine particles of approximately 0.1 μm, despite the use of prefilters, which are not addressed by conventional technologies.

Innovation Solution

Incorporating a glass filter medium layer upstream of a porous fluorine resin membrane, with specific node size and distance adjustments in the resin membrane to manage particle adhesion and aggregation, ensuring 2.0 μm2≤S95≤8.0 μm2 and D50≥3.0 μm for nodes and inscribed circles, respectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a porous fluorine resin membrane is used as a surface filtration media to collect particles, then collection efficiency is improved, but pressure drop increases due to clogging

Engineering Contradiction:

Improvecollection efficiencyVSAvoidpressure drop increase

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention segments the filtration function by introducing a prefilter layer upstream of the porous fluorine resin membrane. The prefilter collects coarse particles (1-50 μm) while the fluorine resin membrane collects fine particles (approximately 0.1 μm), dividing the particle size range into distinct filtration zones to prevent clogging of the high-efficiency membrane

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The prefilter acts as an intermediary element between the incoming air and the porous fluorine resin membrane. It intercepts and collects larger particles before they reach the fine-pore membrane, serving as a protective barrier that maintains membrane performance and extends service life

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of stationary object

If a prefilter is placed upstream to collect coarse particles, then clogging of the porous fluorine resin membrane is suppressed, but fine particles of approximately 0.1 μm still cause pressure drop increase

Engineering Contradiction:

Improveservice lifeVSAvoidpressure drop from fine particles

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The invention optimizes critical parameters of the porous fluorine resin membrane including pore size (0.03-0.1 μm), porosity (30-80%), and thickness (1-100 μm) to balance collection efficiency for fine particles with resistance to clogging. These parameter adjustments enable the membrane to maintain performance even when exposed to fine particle environments

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the pore size of the porous fluorine resin membrane is reduced to collect fine particles, then collection efficiency for fine particles is improved, but clogging occurs more rapidly

Engineering Contradiction:

Improvecollection efficiency for fine particlesVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The filtration system is segmented into two functional layers: a prefilter for coarse particles and a porous fluorine resin membrane for fine particles. This segmentation allows the membrane to operate at optimal pore sizes for fine particle collection without being overwhelmed by larger particles that would cause rapid clogging

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The prefilter performs preliminary action by collecting coarse particles before they reach the porous fluorine resin membrane. This preliminary filtration step prepares the airflow by removing larger contaminants, allowing the membrane to focus on fine particle collection without premature clogging

Inventive Principle:

Principle #10Preliminary action

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 solution effectively suppresses pressure drop increases while maintaining high collection efficiency for fine particles, extending the service life of the air filter medium.

Implementation Method 1

Porous fluorine resin membranes generally function as surface filtration media that collect collection objects that are objects to be collected at their surface portions

Methodology Applied

Scientific EffectSurface filtration: Filter (physical)

Implementation Method 2

fine particles having a particle size of approximately 0.1 μm and contained in the atmosphere adhere not only to fibrils but also to fluorine resin nodes connected to the fibrils

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 3

a glass filter medium layer, wherein the glass filter medium layer and the porous fluorine resin membrane are placed in this order from upstream to downstream

Methodology Applied

Scientific EffectDepth filtration: Filter (physical)

Data Source

PatentUS20260077285A1Air filter medium, filter pleat pack, and air filter unit

Publication Date: 2026.03.19 NITTO DENKO CORP

AI summary

An air filter medium including a porous fluorine resin membrane, the air filter medium further including a glass filter medium layer, wherein the glass filter medium layer and the porous fluorine resin membrane are placed in this order from upstream to downstream of the air filter medium configured to allow airflow to pass through the air filter medium. The porous fluorine resin membrane includes a plurality of nodes and a plurality of fibrils, and in an area distribution of the nodes, when an area of the node corresponding to a cumulative relative frequency of 95% from a smaller area is defined as S95, the porous fluorine resin membrane satisfies 2.0 μm2≤S95≤8.0 μm2.