Polytetrafluoroethylene (PTFE) is currently the most widely used fluoropolymer. It is the most chemically resistant plastic, has the best dielectric properties and a wide operating temperature range. It is called the "Plastic King".
PTFE has high temperature resistance (it can be used in the temperature range of 200~260℃ for a long time), low temperature resistance (it can be used for a long time below -100℃), corrosion resistance (high chemical inertness), weather resistance (high resistance Atmospheric aging performance), high lubrication (with a very small coefficient of friction), non-adhesion (very low surface tension, not easy to adhere), good human compatibility (with good physiological inertia, non-toxic), electrical insulation Good (high insulation and not affected by temperature and humidity) and a series of advantages, these characteristics of PTFE are closely related to its molecular configuration.
The molecular structure of PTFE is similar to polyethylene. It is a symmetrical and non-branched linear polymer, so the molecule is not polar, as shown in the following figure:
Because the unbonded fluorine atoms in the molecules repel each other strongly, the carbon chain of PTFE is twisted into a spiral structure, and the fluorine atoms just completely cover the main chain of carbon atoms, which prevents the carbon atoms from interacting with other substances. react. In addition, the fluorocarbon bond has a very high bond energy of 466KJ/mol, which is the highest bond energy among all chemical single bonds, so the stability of PTFE is very high.
However, PTFE also has its own shortcomings, which are mainly manifested as cold flow, large linear expansion coefficient, thermal conductivity, wear resistance, creep resistance, and outstanding surface non-stickiness. These shortcomings of PTFE make it used in Restricted to a certain extent.
my country is one of the earliest countries in the research and production of PTFE, but in the past it was mainly based on the application of foreign technology for some simple processing, with less in-depth research, and the overall production level and process technology were not high. With years of accumulation and development, especially in the last ten years, the technical level of my country's fluorine chemical industry has developed rapidly. At present, 14 domestic enterprises, including Dongyue, Chenguang, Sanaifu, Juhua, and Meilan, produce PTFE, and 5 have a production capacity of more than 10,000 tons. Since the properties of PTFE are so special, in which areas is it usually used?
PTFE neither dissolves nor swells in any known liquid, so the size of PTFE parts remains unchanged in any corrosive medium, no matter how long they are used. Large thin-walled containers made of PTFE are widely used in the actual operation of laboratories and factories that use corrosive liquids. In addition, they are also widely used in seals, pipeline linings, pumps, valves, etc.
No matter what kind of mechanical equipment, the mutual sliding surfaces need to be lubricated during operation to reduce the friction factor, reduce the wear and heat of the parts, and ensure the normal operation ability, accuracy and power consumption of the mechanical equipment. PTFE's low friction coefficient and self-lubricating properties make it widely used in the manufacture of bearings, piston rings, machine tool guides and sealing materials. However, due to its relatively high cost, it is usually used in precision instruments or environments that require acid and alkali resistance.
PTFE has excellent dielectric properties that do not actually depend on the influence of temperature and frequency, and at the same time has extremely high thermal stability, so it has become an irreplaceable electrical insulating material, especially in high-frequency, high-temperature and humid environments. in.
Nowadays, various forms of PTFE materials play an important role in the field of electrical and electronic insulation. PTFE varnished glass 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 films are used to make capacitors, as insulating layers, gaskets, cables, etc. between instruments; PTFE thin films of different calibers The wall pipes are respectively used to lead out the line bushings, heat shrinkable pipes and spiral pipes, and insulated water pipes of generators.
PTFE membrane structure is a brand-new form of building structure, which integrates architecture, structural mechanics, fine chemical engineering, material science and computer technology, etc., with high technical content.
By coating PTFE resin on the ultra-fine glass fiber fabric, the PTFE membrane material is light in weight, high in strength, fire and flame retardant, self-cleaning, not affected by ultraviolet rays, fatigue resistance, distortion resistance, aging resistance, long service life, and high Features of light transmittance and low heat absorption. It is precisely because of the invention of this cross-epoch membrane material that the membrane structure building has become a modern permanent building.
At present, the development and application of this kind of membrane materials abroad are relatively mature, and there are many manufacturers, such as Mehler and Verseidag in Germany, Taiyoko-gyo in Japan, Zhongxing Chemical Industry Co., Ltd., Chemfab in the United States, and ObeiKan in Saudi Arabia.
PTFE is water-resistant, physiologically inert and non-sticky, so it is used in many tissue repair materials and artificial organ materials, such as artificial blood vessels and heart repair membranes. Moreover, the biggest advantage of PTFE is that it can be sterilized by any method. It will not be denatured by autoclaving or treatment with various disinfectants. Therefore, it is widely used in medical equipment such as sutures, sterilization pads, and injection needles.