Polytetrafluoroethylene

Commonly known as the “King of Plastics”

Polytetrafluoroethylene (PTFE), also known as Teflon, commonly known as the “King of Plastics”, is a high molecular polymer made by polymerizing tetrafluoroethylene as a monomer. Its chemical formula is (C2F4)n. It has excellent heat and cold resistance and can be used for a long time at -180 to 260ºC.

This material is resistant to acids and alkalis, and various organic solvents, and is almost insoluble in all solvents. At the same time, polytetrafluoroethylene has the characteristics of high temperature resistance and its friction coefficient is extremely low, so it can be used as a lubricant and has become an ideal coating for the inner layer of easy-to-clean water pipes.

Physical and chemical properties

A. Stability:

1. Stable at room temperature and pressure, avoid moisture, heat, and high temperature. No real melting point, slowly decomposes above 450℃ and directly turns into gas. At 327℃, the mechanical strength suddenly disappears. Insoluble in any solvent. In addition to reacting with molten alkali metals, it is not corroded by any substance, and even if boiled in hydrofluoric acid, aqua regia or fuming sulfuric acid, sodium hydroxide, it will not change.
2. White, odorless, tasteless, non-toxic powder, commonly known as “plastic king”. It has excellent chemical stability, corrosion resistance, sealing, high lubricity and non-stickiness, electrical insulation and good anti-aging resistance. High temperature resistant, the working temperature is up to 250℃. Low temperature resistant, with good mechanical toughness at low temperature, even if the temperature drops to -196℃, it can maintain an elongation of 5%. Corrosion resistant, inert to most chemicals and solvents, resistant to strong acids and alkalis, water and various organic solvents. Good weather resistance, with the best aging life among plastics. Highly lubricating, with the lowest friction coefficient among solid materials. Non-adhesive, with the lowest surface tension among solid materials, it does not adhere to any substance. Non-toxic, physiologically inert, and has no adverse reactions when implanted in the body as artificial blood vessels and organs for a long time.

B. Solubility:
Insoluble in any solvent

Application fields

A. Anti-corrosion: PTFE materials have been widely used in many industries such as petroleum and textiles due to their outstanding corrosion resistance. Representative ones include exhaust pipes, steam pipes, high, medium and low pressure pipelines, valves, etc. Especially in harsh environmental conditions such as low temperature and anti-sticking where conventional materials cannot be used, the advantages of PTFE are more reflected.

B. Electronic and electrical: The dielectric constant of polytetrafluoroethylene is relatively small, so it can be used to prepare enameled wires and thus used in micro motors. In addition, fluoroplastic film has a certain selective permeability to various gases, so this feature can be used to prepare oxygen sensors. Nowadays, various forms of PTFE materials play an important role in the field of electronic and electrical insulation. PTFE glass varnish cloth and glass cloth are used to make high-temperature and high-frequency insulating materials, which can be used in satellite communications and computers; PTFE film is used to make capacitors, as insulating layers, gaskets, cables, etc. between instruments; PTFE thin-walled tubes of different diameters are used for lead-out wire sleeves, heat shrink tubes and spiral tubes, and insulating water pipes for generators.

C. In medical and medical applications: Due to the excellent biocompatibility of polytetrafluoroethylene, many people have conducted in-depth research on it as a biomaterial in recent years. In recent years, domestic and foreign countries have developed PTFE membranes as artificial organs, such as artificial blood vessels, heart valves, etc. For example, it has been used as artificial blood vessels and prosthetic stent materials in nose plastic surgery in clinical practice, and good results have been achieved.

D. In construction: By coating PTFE resin on ultra-fine glass fiber fabric, PTFE membranes are light in weight, high in strength, fireproof, self-cleaning, unaffected by ultraviolet rays, fatigue-resistant, twist-resistant, aging-resistant, and have a long service life. It has high light transmittance and very little heat absorption. It is precisely because of the invention of this cross-era membrane material that membrane structure buildings have become modern permanent buildings.

E. Low friction performance in load: Because its friction coefficient is relatively low compared to most solid materials, filled PTFE has gradually evolved into an excellent material for oil-free lubrication of various parts. It has a wide range of uses, including bearings, piston rings, supporting sliders of steel structure roof trusses, and bridge swivels in chemical equipment.

What are the recycling methods of PTFE?

A. Recycling of waste PTFE products Waste plastic bottles, barrels, pipes, etc. can be used as fuel after being crushed.

B. Incineration of waste plastic bottles, barrels, etc. The waste can be directly put into the incinerator for burning, or a layer of asbestos or iron sheet can be laid on the waste and then put into the incinerator for burning; the garbage can also be poured into the incinerator for high-temperature incineration.

C. Treatment of waste plastic packaging bags Using its high tensile strength and strong toughness, it can be cut into small pieces for the construction industry and the production of mechanical parts.

D. Treatment of waste electrical and electronic products The metal parts in waste electronic products can be melted and reflowed; the printed circuits on the circuit board can be removed by etching; the insulating layer can be removed by organic solvents; the glass shell can be softened by heating to facilitate processing.

E. Treatment methods for packaging containing PVC resins For waste containing PVC resins, physical methods (including mechanical and chemical methods) should be considered for separation and recycling, and then different disposal methods should be adopted according to different situations.

F. Other applications In chemical production, it is widely used as a catalyst carrier, filter medium, and purification equipment lining material. In addition, it is also widely used as an anti-sticking coating material and anti-corrosion coating.