Composite PTFE Membrane for Ultrafiltration via Sintered Porous Layer
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Solution Overview
Problem
Traditional PTFE membranes have pores larger than 0.1 μm and non-uniform size distribution, limiting their application to microfiltration, and are unable to effectively separate particles smaller than 0.1 μm, such as in ultrafiltration processes.
Innovation Solution
A composite PTFE membrane is created by coating a suspension solution of PTFE fine powders on an expanded PTFE membrane and subjecting it to a sintering process with simultaneous cooling on the opposite side, which fuses the PTFE particles to form interconnected channels with smaller pore diameters, reducing sintering time and preventing membrane shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional stretching method is used to manufacture ePTFE membranes, then the membrane structure is simple and easy to manufacture, but the pores are larger than 0.1 μm and not uniform, limiting application to microfiltration only
Solution Approach 1:
The patent creates a composite structure by coating PTFE fine powder suspension on an ePTFE membrane substrate, then sintering to form a porous layer with smaller, more uniform pores. This composite approach combines the ease of manufacturing ePTFE membranes with the precision of controlled pore formation through sintering, achieving both microfiltration and ultrafiltration capabilities.
Solution Approach 2:
The patent changes the manufacturing parameters by using sintering temperature and quenching rate to control pore size and distribution. By adjusting the sintering temperature and cooling rate, the patent achieves uniform pores smaller than 0.1 μm, extending application to ultrafiltration while maintaining manufacturing feasibility.
2Productivity
If sintering temperature is elevated to reduce sintering time, then productivity increases, but the ePTFE membrane substrate shrinks seriously
Solution Approach 1:
The patent applies preliminary anti-action by performing simultaneous cooling on the back side of the membrane during sintering. This counteracts the thermal expansion and shrinkage forces, allowing high-temperature sintering to reduce processing time while preventing serious membrane substrate shrinkage through the opposing cooling action.
Solution Approach 2:
The patent uses a cooling system as an intermediary to mediate between the high-temperature sintering process and the membrane substrate. The cooling system acts as a counterbalancing mechanism that enables rapid sintering without causing excessive shrinkage, thus improving productivity while maintaining membrane integrity.
3Manufacturing precision
If PTFE fine powders are coated and sintered to form smaller pores, then ultrafiltration capability is achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent segments the membrane structure into two functional layers: the original ePTFE membrane substrate providing mechanical support and basic filtration, and the sintered porous layer providing ultrafiltration capability with uniform small pores. This segmentation allows each layer to be optimized independently, achieving precise pore size control while keeping the overall process manageable.
Solution Approach 2:
The patent applies preliminary action by first coating the PTFE fine powder suspension on the ePTFE membrane before sintering. This preliminary coating step prepares the surface for controlled pore formation, enabling ultrafiltration capability to be achieved through a systematic multi-step process rather than attempting to create the structure in a single complex operation.
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 resulting composite PTFE membranes have smaller pores than traditional membranes, enabling their use in ultrafiltration and extending their application beyond microfiltration, with improved pore uniformity and reduced sintering time.
Implementation Method 1
a sintering process that fuses the polytetrafluoroethylene (PTFE) particles
Implementation Method 2
a simultaneous cooling process on the other side, so as to prevent serious shrinking of the ePTFE membrane
Data Source
AI summary
The present invention discloses discloses a composite PTFE membrane comprising an expanded PTFE membrane as substrate and a sintered porous PTFE membrane on top of it. The porous PTFE membrane on top has porous structure with interconnected channels formed with a sintering process that fuses the PTFE fine powders coated on the ePTFE membrane. Furthermore, the present invention discloses a method for forming the composite PTFE membrane.