PTFE seal material has excellent properties and is widely used in industry and people’s lives. This article will take you to explore why it is so popular. You will understand its comprehensive knowledge and apply it correctly to your seals.
Definition
PTFE seal material is mainly a high-efficiency sealing material made of polytetrafluoroethylene resin, abbreviated as PTFE , and its trade name is “Teflon”. It is one of the best corrosion-resistant materials in the world today, so it is known as the “King of Plastics”. It is a polymer compound formed by the polymerization of tetrafluoroethylene, with excellent chemical stability, low friction, corrosion resistance, sealing, high lubricity and non-stickiness, electrical insulation and good anti-ageing resistance. It can work for a long time at temperatures from -180℃ to +250℃. It can withstand all other chemicals except molten metal sodium and liquid fluorine and will not change when boiled in water.
History
PTFE seal material was first discovered by Dr. Royplukett of DuPont in 1938 by a chance. He accidentally discovered a tetrafluoroethylene polymer while studying fluorine-containing refrigerants at the Jackson Laboratory in the United States. One day, Royplukett used tetrafluoroethylene to produce chlorofluorocarbons. A small steel cylinder containing tetrafluoroethylene was placed on a scale and entered the reactor through a flow meter. During the reaction, he found that the tetrafluoroethylene gas stopped flowing out, but the weight of the cylinder did not change. Finally, he opened the cylinder and found a lot of white powder. It is finnaly named Teflon and is registered as a trademark by DuPont. Because of its many performance advantages, it began to be used in PTFE seals materials in the 1940s.
Performance
After the PTFE seal material was manufactured, people found that it was a super strong material. It has the following advantages:
1. Wide temperature range
High-temperature resistance up to +260℃, good thermal stability, and long-term use under high temperature (260℃) conditions will not produce fission or softening phenomenon, boiled in boiling water for dozens of hours，the performance remains unchanged;
It is highly resistant to low temperatures and has good mechanical toughness in liquid nitrogen at -196℃, maintaining 5% elongation.
2. Super corrosion resistance
Compatible with almost all chemicals, including sulfuric acid, hydrochloric acid, nitric acid, caustic soda, etc. Chemical stability exceeds glass, ceramics, and stainless steel.
3. Good non-adhesion
PTFE has perfect low surface free energy and anti-adhesion properties, making its surface smooth, dustproof, and hard to adhere to pollutants.
4. Excellent friction and ageing resistance
PTFE seal material is the lowest friction solid today, is wear-resistant, will not age during long-term use, and has a long service life.
5. Non-toxic, hygienic, and environmentally friendly
PTFE has excellent physical properties such as non-toxicity, sanitation, and environmental protection and can be widely used in high-demand industries such as pharmaceuticals and food.
Limitations
Polytetrafluoroethylene (PTFE) is a common sealing material, but it also has some limitations and has the following disadvantages:
1. Poor creep resistance
Generally, the hardness of pure PTFE products is about 55 Shore A, which makes it unable to withstand excessive pressure in terms of pressure deformation resistance. For example, if the pressure is too high, it is easy to cause plastic deformation or cold flow of the made gasket. It can be modified by adding other fillers to enhance the performance;
2. Low elasticity
PTFE has relatively low elasticity, which may make it unsuitable for applications requiring good elastic sealing performance.
3. High price
Polytetrafluoroethylene’s raw material price is higher compared with other materials. The processing is complex, and high-precision CNC equipment is required. It cannot be processed by moulding methods like other thermoplastics. Almost every moulded part of a specification requires a set of moulds, which makes the processing cost relatively high.
PTFE additives
PTFE additives mainly include bronze, glass fibre, carbon, graphite, and molybdenum disulfide. Generally speaking, filled PTFE can maintain its excellent chemical and high-temperature properties while greatly improving its mechanical strength, stability, and wear resistance. The most commonly used filled are 40% bronze, 25% glass fibre PTFE, and 25% carbon PTFE.
Application
PTFE seal materials are widely used in various mechanical equipment, the automotive industry, the chemical industry, the petrochemical industry, the food and pharmaceutical industry, aerospace, and other fields.
1. Mechanical equipment seals
Because of its low friction, wear resistance, and chemical resistance, it effectively prevents equipment medium leakage and has a long service life.
2. Aerospace seals
PTFE sealing materials can adapt to extreme temperatures and provide stable and reliable seals in aerospace equipment,such as airplanes and rockets..
3. Food and medicine equipment seals
Because PTFE has hygiene and non-toxicity characteristics, it is widely used in equipment sealing in food processing, manufacturing, and other fields.
4. Chemical industry seals
PTFE seal materials have good corrosion resistance, can adapt to various chemical substances, and can be safely applied to the chemical industry.
TYS PTFE SEALS
TYS continues to invest more money and time in the research and development of polytetrafluoroethylene sealing materials. The proprietary modified PTFE material seals developed independently can meet the specific needs of various industries. TYS continues to provide more efficient, safe, environmentally friendly, and corrosion-resistant sealing materials with broad application prospects. In the future, with the continuous development of technology and the continuous improvement of application needs, the application field of polytetrafluoroethylene sealing materials will become increasingly extensive and will also be more comprehensively developed and applied.
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