PTFE seals

PTFE is the abbreviation for polytetrafluoroethylene, an unbranched, linear and semi-crystalline polymer made of the elements fluorine and carbon and is usually a white and odourless solid that belongs to the group of thermoplastics. The best-known trade name for this material, developed in 1938, is probably Teflon™. Another well-known trade name for membranes made of this material is Gore-Tex®.

Flat gaskets made of this material are considered to be almost universally chemically resistant and have a high adaptability. The reason for this is that seals made of PTFE require a low surface pressure in order to achieve the required leakage rates. Due to the physiological harmlessness of this material, its use in the food, medical and pharmaceutical industries is widespread.  

PTFE gasket

Available PTFE qualities at Rehm Dichtungen Ehlers GmbH

If you require seals for chemically demanding environments or in the food or pharmaceutical industries, you can rely on our high-quality PTFE flat seals. In our stock program we keep the material available as sheet material.

We distinguish between two different types of this material. On the one hand, we carry pure PTFE (virgin), which is characterized by its approval for food contact. On the other hand, we offer filled PTFE. The addition of fillers has a positive effect on the properties of the material. Compared to virgin PTFE, the improved mechanical properties, such as pressure resistance and the reduction of creep and cold flow, are particularly noteworthy. The most important fillers for polytetrafluoroethylene in the sealing industry are micro hollow glass beads, barium sulfate and silicate.

Qualities

PTFE 25% glass fibre

This sealing material consists of 25% glass fibres and has virginal better wear properties compared to PTFE.

Technical data sheet:

PTFE 25% glass fibre

Properties:

Density [kg/cm³] 2,21 - 2,35
Tensile strength [MPa] 15 +- 3
Elongation at break [%] 250 +- 50
Compressive force [N/mm²] 40
Temperature range -180° - +280° C
PTFE virginal

Approved for contact with food: EG 1935/2004 (& EU10/2011).

Technical data sheet:

PTFE virginal

Properties:

Density [kg/cm³] 2,21 - 2,35
Tensile strength [MPa] ≥ 25
Melting point 327° C
Temperature range -180° - +260° C

The properties of PTFE as a sealing material

Polytetrafluoroethylene is a polymerization of tetrafluoroethylene and has the highest degree of fluorination and is therefore non-flammable. In addition, PTFE or Teflon™ has good non-stick properties due to a very low coefficient of friction. This material is a high-performance polymer with high dielectric properties and is therefore considered insulating. It should also be emphasized that PTFE seals are UV and weather resistant and also ensure simplified disassembly thanks to a low-adhesion surface.

The sealing material polytetrafluoroethylene is considered thermally stable and retains its mechanical properties in the temperature range from -200° C to +260° C. Due to the high possible temperatures, flat gaskets made of PTFE are among the heat-resistant gasket materials. However, use of the flange gaskets at temperatures above 260° C should be avoided, as the material decomposes to form toxic and corrosive gases. In such applications, flat gaskets made of graphite can be used, since graphite gaskets, just like gaskets made of PTFE, are universally chemically resistant.

With regard to the chemical properties of this material, it can be stated that PTFE seals have outstanding chemical resistance to almost all chemicals and are thus considered to be universally chemically resistant. Aggressive chemicals, concentrated acids and alkalis, strongly oxidizing substances and solvents have no effect on the seal.

With the aid of the aforementioned chemical stability, the material is considered biocompatible and physiologically safe. Finally, our virgin PTFE has EC 1935/2004 approval and is FDA-compliant. For this reason, the sealing material is used for applications in the food industry and in medical technology. 

The advantages and material properties of PTFE at a glance

This thermoplastic is a particularly suitable material for use in environments with high thermal requirements. At the same time, the sealing material has diverse chemical properties and is thus considered to be universally resistant.

PTFE is resistant to:

  • Heat
  • Weather and ozone
  • Light
  • Abrasion resistance
  • Petrol/Diesel
  • Water at 100° C
  • Oils, alkalis and acids

Furthermore, the material is antistatic as well as a good insulator. According to food regulations such as EC 1935/2004 (& EU10/2011), the material can be used in contact with food. Thanks to its abrasion resistance, the thermoplastic is also excellently suited for use as a sealing material.

Areas of application for PTFE seals

Since the material has very good chemical resistance, it is used wherever workpieces come into contact with aggressive chemicals. The range of applications is further extended by various compounds or admixtures of other substances. Polytetrafluoroethylene can be used in a wide variety of applications, especially in sealing technology, thanks to its low friction behavior. In industry, PTFE flat gaskets are used as lining materials for pipelines, as non-stick coatings, as excellent insulating materials and more.
Since the material is biocompatible, it can be used in the food sector as well as in food and medical technology.

We will be happy to answer whether the plastic is also suitable for your purposes. Contact our customer service and let us advise you comprehensively.

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FAQ

What are PTFE seals?
PTFE gaskets belong to the group of thermoplastics, are plastic gaskets and are generally available in the form of sheets. The PTFE sheets supplied by the manufacturer are produced into your individual seals using various manufacturing processes.
What are the properties of PTFE seals?
The sealing material is non-flammable due to its high degree of fluorination. Furthermore, the material has a low coefficient of friction and thus has good non-stick properties. In particular, the material's chemical resistances allow it to be used in environments with aggressive chemicals. In addition, PTFE is dielectric and thus insulating. Furthermore, PTFE is characterised by the fact that it is PAH-free.
What resistance do PTFE seals offer?
PTFE seals have good resistance to heat, petrol, oils, alkalis and acids. PTFE is also resistant to weathering and ozone. Another advantage of this material is that PTFE is antistatic and can therefore be considered a good insulator. The sealing material is also approved for use in contact with foodstuffs, as it complies with the relevant food regulations according to EC 1935/2004 (& EU10/2011) and is also FDA-compliant.
Can PTFE gaskets also be equipped with self-adhesive?
Seals made of PTFE can be equipped with basic self-adhesive features. In the first production step, the unprocessed sheet material is bonded with a self-adhesive film in order to subsequently produce your self-adhesive seals.
Are PTFE seals temperature resistant?
In the temperature range between -180 and +260 degrees Celsius, PTFE can be considered temperature-resistant or heat-resistant.
In which forms can PTFE be obtained from Rehm Dichtungen?
Just as with all our sealing materials, we use this material to produce the right seals, gaskets or blanks for you using our waterjet cutting machines. In addition to the manufactured PTFE seals, we can also cut the unprocessed sheet material to the desired length and width. Finally, you can also purchase PTFE sheets from us as unprocessed yard goods for your own production. All products available from us for this material can also be equipped with self-adhesive on one side.
Which PTFE is available from Rehm Dichtungen?
At Rehm Dichtungen Ehlers GmbH, we stock PTFE virgin, which is also approved for food contact in accordance with EC 1935/2004 (& EU10/2011), as well as PTFE 25% glass fibre in various thicknesses as standard.