Layered PTFE Filter Medium to Limit Filtration Loss During Cleaning

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

PTFE porous membranes used in filter mediums are prone to damage from external forces during dust removal, leading to a decrease in filtration performance, and existing designs do not adequately address the issue of brush use.

Innovation Solution

A laminate structure composed of a first PTFE porous membrane as the exposed surface and a second PTFE porous membrane sandwiched by air-permeable supporting members, with a transmittance ratio of 100 or more, ensuring the exposed surface can be easily cleaned while maintaining filtration performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a PTFE porous membrane is used as the exposed surface for easy dust removal, then dust can be easily removed by blowing or washing, but the thin membrane is easily damaged by external force such as brushing

Engineering Contradiction:

Improveease of dust removalVSAvoidfiltration performance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The filter medium is divided into multiple functional layers: a first PTFE porous membrane as the exposed surface for dust removal, and a second PTFE porous membrane protected by air-permeable supporting members for filtration. This segmentation allows each layer to specialize in its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the filter medium are assigned different properties: the first PTFE porous membrane on the exposed surface has properties optimized for dust removal ease, while the second PTFE porous membrane has properties optimized for filtration performance and is protected from external forces by supporting members.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the PTFE porous membrane is made thinner to improve dust removal ease, then dust can be more easily blown or washed off, but the membrane becomes more susceptible to damage from external force

Engineering Contradiction:

Improveease of dust removalVSAvoidmembrane durability

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The filter medium separates the dust removal function (first PTFE porous membrane) from the filtration function (second PTFE porous membrane), allowing the first membrane to be optimized for ease of dust removal while the second membrane maintains sufficient strength for filtration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Air-permeable supporting members are placed beforehand to protect the second PTFE porous membrane from external forces, preventing damage before it occurs while allowing the first membrane to be easily cleaned.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If a single PTFE porous membrane is used for both dust removal and filtration, then the structure is simple, but the filtration performance decreases when dust is removed from the surface

Engineering Contradiction:

Improvefilter medium structureVSAvoidfiltration performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The filter medium is segmented into multiple layers with distinct functions: the first PTFE porous membrane handles dust removal while the second PTFE porous membrane maintains filtration performance, eliminating the performance degradation issue of single-membrane designs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The filter medium uses a composite structure combining multiple PTFE porous membranes and air-permeable supporting members, where each material contributes its optimal properties to the overall system performance.

Inventive Principle:

Principle #40Composite materials

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 laminate structure allows for easy dust removal on the exposed surface without significantly impacting filtration performance, as the second PTFE porous membrane, protected by the supporting members, maintains filtration efficiency even when subjected to external forces.

Implementation Method 1

a first PTFE porous membrane... Dust deposited on this surface can be removed more easily than dust deposited on the air-permeable supporting member

Methodology Applied

Scientific EffectLow surface energy of PTFE: Surface Tension

Implementation Method 2

the second PTFE porous membrane sandwiched by the air-permeable supporting members to be less affected by external force secures the filtration performance of the filter medium

Methodology Applied

Scientific EffectPhysical barrier protection: Physical Containment

Data Source

PatentUS12403429B2Filter medium and filter unit

Publication Date: 2025.09.02 NITTO DENKO CORP

AI summary

A filter medium of the present disclosure has a laminate structure composed of a first polytetrafluoroethylene (PTFE) porous membrane, a first air-permeable supporting member, a second PTFE porous membrane, and a second air-permeable supporting member laminated in this order. The first PTFE porous membrane constitutes an exposed surface of the filter medium. A ratio of a transmittance of the first PTFE porous membrane to a transmittance of the second PTFE porous membrane is 100 or more. The filter medium of the present disclosure is a filter medium which includes the PTFE porous membranes, from which dust deposited on a surface over a period of use can be easily removed, and which has excellent reusability demonstrated by reduction of a filtration performance decrease caused by removal of dust.