Porous Membrane Laminate Bubble Point and Roughness Control
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Solution Overview
Problem
Current microfiltration filters, particularly those used in the semiconductor and liquid crystal fields, struggle to effectively capture microparticles smaller than 0.5 μm due to lower fiber density and increased clogging, leading to reduced performance and shorter filter life.
Innovation Solution
A porous membrane laminate comprising one or more porous membranes with polytetrafluoroethylene (PTFE) as the main component, designed to satisfy the formula P/γ > -31.6×lnRa+168, where P is the average bubble point, γ is the surface tension of a test liquid, and Ra is the surface roughness of the porous membrane, ensuring high fiber density and improved capturing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional porous membranes with PTFE are used for filtration, then the filter can capture particles, but the fiber density is insufficient leading to poor capturing performance for microparticles less than 0.5 μm
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness (Ra) within 14-96 nm and establishing a specific quantitative relationship between bubble point (P) and surface tension (γ) where P/γ > -31.6×ln(Ra)+168. These parameter optimizations enable the membrane to achieve high fiber density without compromising other performance characteristics, thereby improving microparticle capturing performance while maintaining structural integrity
Solution Approach 2:
The patent employs composite materials by combining polytetrafluoroethylene (PTFE) with other materials to create a laminated structure. This composite approach allows the filtration layer to achieve higher effective fiber density and improved particle capture capability while the PTFE component maintains its inherent chemical stability and heat resistance properties
2Reliability
If the membrane structure is optimized for high fiber density, then capturing performance improves, but the membrane may become more prone to clogging
Solution Approach 1:
The patent applies local quality by creating distinct functional zones within the membrane structure. The surface layer is optimized with specific roughness (Ra: 14-96 nm) for initial particle capture, while the bulk structure maintains appropriate porosity and pore size distribution to prevent clogging. This spatial differentiation of properties allows high capturing performance at the surface without compromising overall filter longevity
Solution Approach 2:
The patent implements preliminary action by pre-optimizing the surface roughness and pore structure before the filtration process begins. The controlled surface morphology prepares the membrane to capture particles efficiently from the outset, while the pre-designed pore distribution prevents rapid clogging, thereby extending filter life before maintenance is required
3Reliability
If the surface roughness is increased to improve particle capture, then capturing performance enhances, but the mechanical strength may be compromised
Solution Approach 1:
The patent applies parameter changes by establishing an optimal surface roughness range (Ra: 14-96 nm) that balances particle capture performance with mechanical strength. Within this controlled range, the surface morphology is sufficient to enhance microparticle interception while the bulk membrane structure maintains adequate tensile and structural properties for practical application
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 porous membrane laminate achieves enhanced capturing performance for microparticles by ensuring high fiber density throughout the membrane, reducing clogging, and extending the filter's lifespan while maintaining high mechanical strength.
Implementation Method 1
a porous membrane laminate having one or more porous membranes comprising polytetrafluoroethylene as a main component, and having a specific relationship between a bubble point, a surface tension of a test liquid, and a surface roughness
Implementation Method 2
higher fiber density of the porous membrane inside gives a higher average bubble point P... increased the opportunity for particles flowing in the thickness direction to collide with fibers
Implementation Method 3
particles are captured in the broad range from the surface to the inside, and the clogging thereby hardly occurs, the effect of elongating the life of the porous membrane can be anticipated
Data Source
AI summary
A porous membrane laminate according to one aspect of the present disclosure has one or more porous membranes containing polytetrafluoroethylene as a main component, wherein the porous membrane laminate satisfies a following formula (1):P/γ>-31.6×lnRa+168(1)wherein P is an average bubble point [kPa]; γ is a surface tension [dyn/cm] of a test liquid used in measurement of the average bubble point; and Ra is a surface roughness [nm] of the porous membrane, and 14 nm≤Ra≤96 nm.