Moisture Permeable Filter Medium Laminating PTFE Film With Polyolefin Sheet
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Solution Overview
Problem
The use of a PTFE porous film as a moisture permeable filter medium results in poor handling due to its thin and non-stiff nature, leading to a reduction in moisture permeability when laminated with an air permeable sheet, which impairs the effective transfer of water vapor between surfaces.
Innovation Solution
A moisture permeable filter medium is formed by laminating a hydrophobic PTFE porous film with a hydrophilic air permeable sheet, where the hydrophobic layer is composed of a PTFE porous film and the hydrophilic layer is made of non-woven fabrics, allowing for improved stiffness and moisture permeability while minimizing the reduction in moisture permeability caused by lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PTFE porous film is used as a moisture permeable filter medium, then moisture permeability is improved, but handling becomes poor due to thin and non-stiff nature
Solution Approach 1:
The patent combines a PTFE porous film (providing moisture permeability) with a polyolefin porous sheet (providing stiffness and handleability) to create a composite filter medium. The PTFE layer maintains the moisture permeation function while the polyolefin layer provides mechanical strength and rigidity, resolving the contradiction between moisture permeability and handling ease.
2Ease of operation
If an air permeable sheet is laminated to the PTFE porous film to improve stiffness, then handleability is improved, but moisture permeability decreases due to increased thickness
Solution Approach 1:
The patent optimizes the thickness parameters of both the PTFE porous film and the polyolefin porous sheet to minimize the overall thickness while maintaining sufficient stiffness. By carefully selecting thickness values, the patent reduces the negative impact on moisture permeability while still achieving improved handleability through the laminated structure.
Solution Approach 2:
The patent uses a composite structure where the PTFE porous film (thin layer providing moisture permeability) is laminated with a polyolefin porous sheet (thicker layer providing stiffness). This composite approach allows the system to achieve both improved handleability and minimized moisture permeability reduction by leveraging the complementary properties of the two materials.
3Strength
If the filter medium is made thicker to improve stiffness, then handleability is improved, but water vapor transfer efficiency decreases
Solution Approach 1:
The patent creates a composite filter medium with a PTFE porous film layer (thin, providing moisture permeability) and a polyolefin porous sheet layer (thicker, providing stiffness). The PTFE layer acts as the primary moisture vapor transfer pathway, while the polyolefin layer provides mechanical support, thereby maintaining high water vapor transfer efficiency despite increased overall thickness.
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
This configuration enhances the moisture permeability of the filter medium, allowing water vapor to effectively permeate from one surface to the other, maintaining high moisture transfer rates similar to the PTFE porous film alone, while providing improved handleability.
Implementation Method 1
a PTFE porous film... is known to have good moisture permeability... the movement of the water vapor (by permeating through the moisture permeable filter medium) from the gas having higher humidity to the gas having lower humidity is enabled
Implementation Method 2
a hydrophilic air permeable sheet... allowing for improved stiffness and moisture permeability
Data Source
Figure 1
AI summary
Provided is a moisture permeable filter medium formed by laminating a hydrophobic layer having hydrophobicity and a hydrophilic layer having hydrophilicity together, in which one of the hydrophobic layer and the hydrophilic layer is composed of a PTFE porous film formed using PTFE, and the other of the hydrophobic layer and the hydrophilic layer is composed of an air permeable sheet to which air is permeable.