【Deep Coating Society Popular Science Knowledge】Invention and application of polytetrafluoroethylene

Polytetrafluoroethylene [PTFE, F4] is one of the best corrosion resistant materials in the world today, so it is known
as the "plastic king".
It can be used for a long time in any kind of chemical media, PTFE seals, gaskets, gaskets.
PTFE seals, gaskets and sealing gaskets are molded and processed
by suspended polymerized PTFE resin.
Compared with other plastics, PTFE has excellent chemical corrosion resistance and temperature resistance, and it has been widely used as a sealing and filling material
.

The additives of PTFE are mainly glass fiber, carbon, graphite, molybdenum disulfide and bronze
.
In general, the filled PTFE retains its excellent chemical and high-temperature properties, but at the same time the filler greatly improves its mechanical strength, stability and wear characteristics
.
Among them, the commonly used 25% glass fiber PTFE and 25% carbon PTFE are the most commonly used
.
It is widely used in packaging, electronic appliances, chemical energy, corrosion-resistant materials, etc
.

The discovery of PTFE?

In 1938, Prenkitt, a chemist at Jackson Laboratory in the United States, was developing a new type of refrigerant
.
He became interested in chlorofluoroolefins because the tetrafluoroethylene gas was unstable, and he stored tetrafluoroethylene in
cylinders cooled on dry ice.
One day, Prenkit used tetrafluoroethylene to produce CFCs, and small cylinders containing tetrafluoroethylene were placed on a bench 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
at all.
Out of curiosity, Prenkit removed the cylinder valve and sawed the cylinder open, which turned out to be quite a bit of white powder
.
This is PTFE, a polymer of tetrafluoroethylene, later named: Teflon
.

After PTFE was manufactured, it was found to be a super-strong material
.
It is very hardy and also has good mechanical toughness in liquid nitrogen at -196 °C, maintaining an elongation
of 5%.
It can even withstand liquid helium at -268.
785 °C; it is resistant to high temperatures, operating temperature up to 250 °C; it is particularly resistant to corrosion and is inert to most chemicals and solvents
.
Whether it is sulfuric acid, hydrochloric acid, nitric acid, caustic soda, it cannot touch half a hair
.
Chemical stability exceeds glass, ceramics, stainless steel
.
Boiled in boiling aqua regia for dozens of hours, but still the same
.

PTFE is particularly difficult to be wetted, soaked in water for a year, it does not swell and does not increase in weight; It has good lubricity, is the lowest friction coefficient among solid materials, and also has the smallest surface tension, and does not adhere to any substance; It is non-toxic, physiologically inert, and has no adverse reactions
as artificial blood vessels and organs implanted in the body for a long time.

In addition, PTFE has particularly good dielectric properties and can resist 1500 volts of high voltage, making it a good insulation material
in electrical appliances.

PTFE is also a new type of medical polymer material

It is made
of PTFE resin by special processing methods such as stretching.
White, elastic and flexible, with a network structure formed by microfiber connection, these microfibers form countless fine pores, so that expanded PTFE can be bent arbitrarily, good blood compatibility, biological aging resistance, etc
.

Expanded PTFE material is purely inert, has a very strong biological adaptability, does not cause rejection of the body, has no physiological side effects on the human body, can be sterilized by any method, and has a multi-porous structure, allowing it to be used in a variety of rehabilitation solutions, including artificial blood vessels and mesh for soft tissue regeneration and surgical sutures for vascular, cardiac, general surgery and orthopedic surgery
.

PTFE is widely used in the anti-stick aspect of non-stick pans

In 1954, Gregoir, a French engineer who loves fishing, in order to prevent the fishing line from entanglement and knots, coated PTFE on the fishing line.

Inspired by this, he developed a method of coating PTFE on the surface of the pot, and the world's first "non-stick pan" was born
.

PTFE material has the smallest surface tension in solid materials, does not adhere to any substance, and also has excellent high and low temperature resistance, so that it is widely used in anti-stick applications such as the manufacture of non-stick pans
.
Its anti-stick process mainly includes two types: the PTFE part or sheet is mounted on the substrate, and the PTFE coating or the lacquered cloth laminated with glass is heat shrinkable and sheathed on the
substrate.

PTFE is a very stable substance, almost completely chemically inert, very good heat resistance, below 400 degrees will not decompose, as long as the pot is not dried and burned, daily cooking generally does not have thermal decomposition to produce toxic substances
.
However, it is not suitable for microwave heating
.
Looking at the PTFE material itself, it may be the most stable and safe plastic
.

The application of PTFE in 5G is significant

5G is a network that can meet explosive data needs anytime, anywhere, and 5G wireless networks will use higher frequency band transmission technology
in mobile and fixed networks.
To achieve high-frequency transmission, materials with low dielectric constant and low dielectric loss must be used
.
PTFE's low moisture absorption, electrical stability, and excellent chemical inertness are ideal for data transmission cables
that require low attenuation.
As one of the materials with the lowest intermediate electrical constant of organic materials, it will be widely used in the field of 5G communication in the field of base station filters, high-frequency high-speed PCB/FPC, 5G chip processes, high-frequency connectors, cables and other fields
.

The motherboard of the 5G mobile phone uses a printed circuit board (PCB) based on a high-frequency copper clad laminate to reduce signal loss
.
The RF signal transmission between the RF module and the antenna module of the 5G mobile phone is completed by PTFE fine RF coaxial cable, ensuring low loss of high-frequency and high-speed signals of mobile phones
.

With the continuous development of material application technology, the three major shortcomings of PTFE materials: cold flow, difficult welding, and difficult melt processability are gradually being overcome, so that its application prospects in optical, electronic, medical, petrochemical oil transmission and impermeability prevention and other fields are broader
.

Source: Dongsheng Rubber

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