Durable Hydrophobic Membranes with Superior Chemical Resistance
Sintered PTFE Hydrophobic Membrane Technology
Made from 100% pure PTFE that is free of PFOA, supporting layers, additives, and processing aids, Porex Virtek® PTFE membranes (Polytetrafluoroethylene) use patented and proprietary processes to sinter, skive, then roll the membrane material so that it can be converted into numerous other forms. Using a controlled manufacturing process, Porex is able to ensure a consistent and repeatable pore structure that provides outstanding strength, durability, chemical and thermal resistance, and design flexibility. Naturally hydrophobic, these sintered PTFE membranes allow for air and gasses to freely pass through while preventing the ingress of liquid water, dust, and other contaminant debris.
To address some of the most demanding medical and industrial applications, our PTFE membranes are capable of filtering particles as small as 0.1 micron in environments up to 500°F. This waterproof membrane is extremely durable and provides superior chemical resistance to aggressive media and corrosive solvents that can impact device functioning and overall performance.
Master rolls are 330 mm wide on 3” cores and can be converted into many forms including sheets, slit rolls, die-cut parts, plugs and discs, adhesive-backed, rolled or thermoformed parts, and many others. They are available in unlaminated and laminated options.
Like our porous plastics, PTFE membranes are sintered using a combination of heat and pressure to bond the materials together. The objective is not to melt or change the main properties of the material – but to create a customized porous material specific to the customer’s needs and applications. PTFE membranes are unique, though, as they undergo an additional skiving process that involves cutting the sintered form into a thinner membrane that can be converted into many other forms.
When incorporating a sintered PTFE membrane into your product, it’s critical to understand the physical properties impacting the materials and functionality of the part including:
Understanding typical material properties will guide you in selecting the right polymer for your device’s function and operating conditions. The above characteristics can be highlighted or downplayed based on your specific product needs. Below is a chart that shows the common materials with their physical properties; however, this is not an exhaustive list.
Air flow rate: the volume of air being delivered at a given pressure drop through a specific area. This is a critical measure for designing a venting membrane. One important thing to note – air flow rate will increase through the same vent as the pressure drop increases.
Water entry pressure (WEP): the amount of water pressure required to have water break through the membrane. This is a critical measure when designing a water-resistant venting or filtering membrane.
Operating temperature: the temperature range at which the part will be required to operate. For Porex Virtek PTFE membrane, this value is 260°C / 500°F continuous.
Other key characteristics: Porex Virtek PTFE membrane is an extremely versatile material that is used in numerous markets and applications. Other application-specific characteristics that may be required for your application can include filtration efficiency, moisture vapor transmission rate, Gurley number, % reflectivity, and dielectric properties.
Chemical properties
Porex Virtek PTFE waterproof membrane is one of the most chemically resistant materials available in the market. There are only a handful of fluorinated acids that are not chemically compatible with sintered PTFE membranes, so it is always your safest choice if unknown chemicals may be in contact with the component.
Chemicals
PTFE
Acids (non oxidizing)
Good
Bases
Good
Oil
Good
Aromatic Solvents
Good
Non-Polar Alphatic
Solvent
Good
Polar-Aprotic Solvents
Good
Polar-Protic Solvents
Good
Halogenated Solvent
Good
Oxidizing Agents
Good
Material options
Polytetrafluoroethylene (PTFE)
For applications in need of ultra-hydrophobicity, high-temperature tolerances, high chemical resistance, and excellent robustness, sintered and skived PTFE membrane technology is a perfect choice.
Using our wide range of customizable solutions, we work closely with your engineering team to define your specifications and select the best PTFE membrane for your application.
Additive options
Below are some common additives and treatments that expand the potential functionality of your PTFE membrane:
Oleophobic treatment
Polypropylene scrim support layer
Adhesive backing
Screen Printing
Geometric options
Porex Virtek PTFE membrane material begins as a 330 mm wide format (between 0.1 and 3.0 mm thick) and can be cut into porous PTFE sheets and other format options such as:
Slit rolls (8 – 330 mm)
Die-cut discs and various shapes
Rotary-cut plugs and discs
Cut discs “in web”
Water jet cut shapes
Zoned adhesive disc and other shapes
Rods & molded or spiral tubes
Thermoformed shapes
Porous PTFE sheets
Our engineers can work with you to better understand your manufacturing process and determine which size, shape, and dimensions are the best fit for your application.
Assembly & converting options
Customizable assembly and converting options for sintered PTFE are endless. Some of the more common methodologies include:
Thermal & ultrasonic welding
Overmolding
Die-cutting
Press fit
Pressure-sensitive adhesive (PSA)
To potentially decrease your assembly time and complexity, our engineers can work with you to better understand how your final product or device will be made. In many cases, we can combine multiple parts into one that is custom engineered.
If you require secondary processing of sheet and film products to meet your product design challenges, Porex also offers a Preferred Converter Program that can serve smaller order quantities.
Porex Virtek® PTFE– General Purpose Venting product range (hydrophobic)
Item Number
IP Rating †
WEP*mbar
(Typical)
Typical Airflow
l/hr/cm² @70mbar
Filtration Efficiency**
>99.99%
Thickness
mm
Max Operating
Temp °C
Salt Fog$
PMV10
64,67
270
107
0.5µ
0.13
260
No Pen.
PMV10L***
64,67
270
85
0.5µ
0.3
100
No Pen.
PMV15
64,67
370
75
0.4µ
0.18
260
No Pen.
PMV15T‡
64,67
370
75
0.4µ
0.18
260
No Pen.
PMV20
64,65,68
520
25
0.1µ
0.25
260
No Pen.
PMV25
65,67,68
765
17
0.2µ
0.1
No Pen.
PMV27
65,66,67,68
1050
7
0.1µ
0.19
260
No Pen.
† IEC std. 60529; IP 68 is a user defined and results must be verified by the user *WEP = Water Entry Pressure ** According to IEST RP-CC007.2 2009 $ASTM B117-11 test method ***Laminated polyolefin mesh backing ‡ Oleophobic, AATCC TM 118 – Grade 8
Moisture Vapor Transmission Rate approx. 900g/m2/day. ASTM E96-16 water escaped from sealed cup @ 23±2°C, 50±10%rH chamber.
Properties are typical and not meant for specifications. Selected options and adhesives may affect properties
RoHS, WEEE, REACH Compliant (PFOA Free)
† IEC std. 60529; IP 68 is a user defined and results must be verified by the user *WEP = Water Entry Pressure ** According to IEST RP-CC007.2 2009 $ASTM B117-11 test method ***Laminated polyolefin mesh backing ‡ Oleophobic, AATCC TM 118 – Grade 8
Moisture Vapor Transmission Rate approx. 900g/m2/day. ASTM E96-16 water escaped from sealed cup @ 23±2°C, 50±10%rH chamber.
Properties are typical and not meant for specifications. Selected options and adhesives may affect properties
RoHS, WEEE, REACH Compliant (PFOA Free)
*Bacterial Filtration Efficiency (BFE) data is based on a modified version of ASTM F2101
** VFE (Viral Filtration Efficiency), † Not tested but similar results to MD20 expected.
*** WEP (Water Entry Pressure)
Properties are typical and not meant for specifications. Selected options and adhesives may affect properties
Complete testing data and information is available upon request – all exceeded the standard BFE value of 98%
RoHS, WEEE, REACH Compliant (PFOA Free)
Common applications for sintered PTFE hydrophobic membrane
This list of application examples is just a small selection of what is possible. Check out our Areas of Expertise to explore a specific application.
Vent
This is the most common functionality of Porex Virtek PTFE membranes. From electrical enclosures, container venting, and diagnostics to medical devices and EV battery vents, many applications rely on venting for their product to work properly. Our durable and reliable PTFE vents are a perfect option to support your needs.
For UVC disinfection devices where a highly reflective and evenly distributed UVC energy is critical to ensuring proper deactivation of pathogens, our sintered PTFE membrane is an excellent choice.
When addressing challenges involving cross-contamination, many devices must function as a filter and vent. Our sterilization container filters, which are reusable, are a prime example, as a vent allows pressure equalization during sterilization, and a filter provides a barrier to bacteria during subsequent storage.
Learn more about the distinctions between sintered Porex Virtek PTFE and ePTFE, enabling you to make informed decisions for your specific applications.
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