Hydrophobic Microporous Membrane Beading Effect
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Solution Overview
Problem
Existing hydrophobic and oleophobic membranes used in ventilation systems lack sufficient resistance to high-energy radiation and temperature stability, and their surface properties do not effectively prevent liquid spreading, which can lead to reduced air permeability and filter clogging.
Innovation Solution
A hydrophobic or oleophobic microporous polymer membrane with a structurally induced beading effect is created by roughening at least one main surface, achieving a contact angle of at least 125° and increased surface roughness, which enhances liquid-repellent properties and prevents liquid spreading, while maintaining radiation resistance and temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the membrane surface is made smooth and hydrophobic, then liquid-repellent properties are achieved, but liquid spreading still occurs reducing air permeability
Solution Approach 1:
The patent applies a porous coating layer on the membrane surface that captures liquid through capillary forces while allowing gas to pass through. The porous structure with specific pore sizes creates capillary pressure that prevents liquid penetration while maintaining high gas permeability, resolving the contradiction between liquid repellency and air permeability.
Solution Approach 2:
The patent uses a composite structure combining a hydrophobic base membrane with a porous coating layer. This composite material approach allows the base layer to provide inherent hydrophobicity while the porous coating enhances liquid capture capability without compromising gas flow, achieving both liquid-repellent properties and maintained air permeability.
2Reliability
If conventional hydrophobic membranes are used, then basic liquid barrier function is achieved, but resistance to high-energy radiation and temperature stability are insufficient
Solution Approach 1:
The patent employs composite materials where the base membrane is made from radiation-resistant and temperature-stable polymers such as PTFE, PVDF, or PES, while adding a porous coating layer. This composite structure combines the thermal and radiation stability of the base material with the enhanced liquid barrier function of the porous coating, achieving both basic liquid barrier function and high resistance to radiation and temperature.
3Reliability
If liquid barrier properties are enhanced, then liquid spreading is prevented, but air permeability may be reduced
Solution Approach 1:
The porous coating layer is designed with specific pore size distributions that create capillary pressure sufficient to block liquid penetration while maintaining open pathways for gas molecules. The porous structure allows the coating to enhance liquid barrier properties without significantly reducing air permeability, as gas molecules can pass through the pores while liquid is blocked by capillary forces.
Solution Approach 2:
The patent applies the porous coating only on the liquid-exposed surface of the membrane, creating local quality enhancement where it is most needed. The coating thickness and pore structure are optimized locally to provide maximum liquid barrier effect while minimizing impact on overall gas permeability, achieving enhanced liquid barrier properties without compromising air permeability.
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 membrane effectively prevents liquid spreading and maintains air permeability, even under condensation, and is radiation-resistant, making it suitable for sterile filtration and as a liquid barrier in ventilated systems.
Implementation Method 1
The hydrophobic character of the sterile filtering separation medium is a prerequisite for installation in a ventilation element... Surfaces with a contact angle of more than 90° with water are called hydrophobic... The roughening of the at least one main surface leads to a contact angle with respect to water of at least 125°
Implementation Method 2
Due to their low surface tension compared to water, these materials have reduced wettability with aqueous and polar media... Their surface tension is below 72 mN/m at 20 °C... Oleophobic substances... have a surface tension of less than 21 mN/m at 20 °C
Implementation Method 3
a hydrophobic or oleophobic microporous polymer membrane... The pore size and the porosity are suitable for the respective application... microporous polymer membrane with a sponge structure
Data Source
Figure 1~2.3
Figure 2.4~2.6
Figure 3
AI summary
The present invention relates to a hydrophobic or oleophobic microporous polymer membrane with structurally induced beading effect, a method for producing the membrane according to the invention, use of the membrane in sterile filtration of gaseous fluids and use of the membrane as a liquid barrier in liquid-containing systems to be ventilated.