About Teflon fluorine plastic science

At present, in the production of wire and cable, commonly used fluoroplastics include polytetrafluoroethylene PTFE, polyperfluoroethylene propylene (FEP), polyvinylidene fluoride (PVDF), tetrafluoroethylene and ethylene copolymer, etc., of course, generally according to the market price In terms of distinction, PTFE stands at the top of fluoroplastics, followed by PFA, and then FEP, At present, FEP is the most widely used and the largest in the market. Of course, some manufacturers choose PVDF/ETFE with a slightly lower temperature grade for related cables. In the cable industry, these are collectively referred to as Teflon or FEP materials. , these materials are mainly used to manufacture various heat-resistant and high-temperature insulated wires, measuring (oil) well cables, geological exploration cables, heating cables, F-class and H-class motor lead wires, Radiation-resistant wires, electromagnetic wires, radio frequency coaxial cables, etc., let's put it this way, all plastics containing fluorine atoms in their molecular structure are collectively called fluoroplastics, which are composed of fluorine-containing monomers. Monomers such as tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, and vinyl fluoride are obtained through homopolymerization or copolymerization. With the continuous development of polymer technology, the variety of fluoroplastics is gradually increasing. The scope is expanding day by day. Since the molecular structure of fluoroplastics contains fluorine atoms, it has many excellent properties, such as excellent electrical insulation properties, high heat resistance, outstanding oil resistance, solvent resistance and wear resistance, and good moisture resistance. and low temperature resistance. Therefore, fluoroplastics occupy an important position in national defense, electromechanical, metallurgy, petrochemical and other industrial sectors. Today we will talk about why fluoroplastics are becoming popular in the cable industry?

Why do we use fluoroplastics?

Performance characteristics of fluoroplastics: polytetrafluoroethylene and perfluoro (ethylene-propylene) copolymer (FEP) are completely composed of carbon atoms and fluorine atoms, while polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF) molecules It also contains hydrogen atoms, and polychlorotrifluoroethylene also contains chlorine atoms. The excellent performance of fluoroplastics is realized by the high binding energy between carbon atoms and fluorine atoms. The main chain skeleton of polytetrafluoroethylene is carbon atoms, and the surrounding is completely surrounded by fluorine atoms, so its various properties are high, while the softening point of PFA, FEP, ETFE and other varieties is lower than that of PTFE due to the influence of side groups, and other properties Also changed.

1. Thermal properties Fluoroplastics are flame retardant and have excellent heat resistance. The continuous use temperature of PTFE and PFA can reach 260°C, and it can be used at 300°C for a short period of time. The use temperature of FEP is 60°C lower than them. The highest PCTFE can be used at 120°C. If fluoroplastics are used at high temperature for a long time, the crystallinity will change, so special attention must be paid when manufacturing equipment linings.

2. Chemical resistance Fluoroplastics have excellent chemical resistance and solvent resistance, especially PTFE, PFA, FEP, etc., which are not corroded by acids, alkalis, and solvents. However, molten alkali metals, fluorine, and chlorofluorocarbons have varying degrees of influence on them. PCTFE, ETFE, PVDF, etc. are slightly less resistant to chemicals in fluoroplastics, but their corrosion resistance is much better than other plastics.

3. Electrical properties The electrical properties of fluoroplastics, especially high-frequency electrical properties, are unmatched by other materials. The polarity of PTFE, FEP, and PFA molecules is very low, the change is very small in a wide temperature and frequency range, the relative permittivity is stable, the dielectric loss is very low, and the electrical insulation is excellent. Among them, PVDF also has specific piezoelectricity and pyroelectricity, which can be used to make piezoelectric materials.

4. Mechanical properties The increase of hydrogen and chlorine atoms in the fluoroplastic molecule increases its tensile strength. The embrittlement temperature of PTFE and PCTFE is extremely low, showing excellent low temperature performance. PTFE has a low friction coefficient and specific self- Lubricity, but PTFE has its own disadvantages such as high wear and cold flow, and various fillers can be used to improve wear resistance and overcome cold flow.

5. Non-stickiness Fluoroplastics have specific non-stickiness. In particular, molecules such as PTPE, FEP, and PFA have high fluorine content, and the surface contact angle is very large, which makes the liquid on the surface of fluoroplastic products spherical. It is not easy to bond with resin, so it is often used to make a non-stick layer on the surface of cookware.

6. Weather resistance: All kinds of fluoroplastics have excellent weather resistance, even if they are exposed to harsh temperatures for a long time, their various properties will not change.

7. Hydrophobic Fluoroplastics have low water absorption, especially PTFE. Its hydrophobicity can be used to make breathable and impermeable composite fabrics and other equipment.

Fluoroplastic family science

In 1972, DuPont of the United States developed a copolymer of tetrafluoroethylene (TFE) and perfluoropropyl vinyl ether (PPVE), the trade name was Teflon PFA, which was a perfluoroalkoxy copolymer. Since then, Daikin Corporation ( Neoflon PFA), Asahi Glass Company (Flon PFA), and European Tailiang Company (Dyneon PFA) have all developed their own PFA products one after another, and have a certain share in the market. The leading manufacturers occupy a certain market share of cable fluoroplastics. Now most of my friends know PTFE. Teflon is the trade name of DuPont (now Chemours). The Chinese names are "Teflon", "Teflon", "Teflon" and "Teflon", in fact, Teflon is not only the trade name of DuPont PTFE, but also the trade name of DuPont's other fluoropolymers, such as FEP resin and PFA, and the common plastics containing fluorine are: PFA, FEP, ETFE, ECTFE, PVDF, PCTFE, etc. Please refer to the following table for details:

Application scenarios of fluoroplastics in the cable industry

Due to the many advantages of fluoroplastics, there are currently many application scenarios in the cable industry

The use temperature should be high: it is not limited to dozens of degrees like PE, PVC, ordinary rubber, and insulating paper, but requires a temperature resistance level of 100°C, 150°C, 200°C, 250°C, or even higher.

The frequency of use should be high: not only be satisfied with power frequency and carrier frequency, but require high frequency and high frequency, up to decimeter wave, millimeter wave, and even 40G, 60G and other high-speed cable applications

Environmental resistance: It can withstand various harsh environments, such as high and low temperature, various climatic conditions, radiation resistance, etc.

High flame retardant: the lowest flame retardant standard is VW-1

Aging resistance: Compared with PVC and PE materials used in conventional cables, it has a long service life and high reliability

Miniaturization: Miniaturization, light weight, no space, and weight reduction are particularly important in aerospace. The reason why fluorine-containing plastic insulated wires and cables are called one of the most important and wide-ranging application fields of fluorine plastics is precisely because fluorine-containing Plastics meet the above requirements in different aspects and to varying degrees.

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High frequency data transmission wire and cable:

Fluoroplastics not only have outstanding electrical insulation, but also have a low dielectric constant and a particularly low loss factor in a wide operating temperature range and frequency range. Dielectric strength, dielectric constant (2.3~2.1), volume resistivity and surface resistivity remain good, and are not affected by temperature up to their glass transition temperature; they have low hygroscopicity, so that the dielectric properties are rarely affected by humidity; the electrical properties of fluoroplastics (F4) do not change over time; They are inert to almost all chemicals and solvents, and can maintain their excellent performance even under high temperature and pressure. They are especially suitable for data transmission cables that require low attenuation. Therefore, they are used in some occasions that require high temperature resistance and fire protection As the insulation medium of radio frequency cables, it is beneficial to improve the quality of the transmission signal. Fluorine plastic is used as the insulation layer and the outer sheath.

Connection wires for key parts in the automotive industry:

Another important use of fluoroplastics is: used as connecting wires in harsh environments, the maximum operating temperature is 250°C, fluoroplastic insulated cables can pass the UL standard 80°C oil resistance test, and fluoroplastic insulated wires are used in many places in cars, such as Cables for automatic transmissions for corrosive oil; gasoline oil level sensors; brake friction sensors, etc.

Network cabling in the construction industry:

With the acceleration of urbanization all over the world, the increase of high-rise buildings, and the strengthening of people's understanding of wire and cable fire accidents, the requirements for cable fire prevention in various fields are also getting higher and higher. The high thermal stability, high flame retardancy, and low loss of fluoroplastics have become the focus of attention. The use of fluorocarbon plastic insulation for connecting wires for special occasions can meet the above requirements. Currently, in some European The country mandates that wiring must use fluoroplastic network cables.

Drilling cables for the oil industry

Since the temperature of the steam to be injected is as high as 300°C and the pressure can reach 20MPa, the inside of the oil well is in a high-temperature and high-pressure environment all the year round. Therefore, for the cables working in this high-temperature and high-pressure environment, how to overcome the harsh environment and make the downhole The transmission of well logging data to the well has become an important issue. Fluoroplastic cables have the characteristics of high temperature resistance, can keep working at a high temperature of 300 ℃, and have excellent pressure resistance performance, so they are also more and more widely used in the petroleum industry. Fluoroplastic with BASF's TPU sheath is currently standard for this type of cable.

Special cables for the power industry:

The application environment of wire and cable in the power industry is very complex, high temperature (stator, rotor, air cooler inlet), soaked in liquid (oil tank, oil pipeline, water pipeline and transformer), easy to be mechanically damaged (machine pit, wind tunnel), and the cable The requirements are very harsh, fluoroplastic cables can effectively overcome these harsh environments, and are suitable for use in cables, high temperature resistant cables in the power industry.

Aerospace cables

Wires and cables are materials that connect the power supply, electrical equipment, and electrical equipment to each other to form an aircraft electrical network. With the increasing development of the aviation industry, the improvement of aircraft performance and the update of airborne equipment, the amount of information transmitted by aircraft Gradually increasing, the transmission lines that play the role of "nerves" and "blood vessels" in the entire aircraft system have higher and higher requirements for their performance, especially the complex internal environment of the aircraft. In addition to performance and chemical properties, factors such as electrical network matching relationship, anti-interference ability, ampacity, operating environment, mechanical strength, and cable protection should also be considered comprehensively. Fluoroplastic cables have lightweight, anti-interference, and excellent physical and chemical properties. , is playing an increasingly important role in aerospace.

other industries

In other aspects, fluorine plastic insulated wires and cables are mainly used for: test instrument wiring, heating wires for household appliances; automatic control cables for electrical detection of chemical equipment; lead wires for halogen bulb fixing frames; thermocouple wires; data records for special oil well drilling equipment Cables, engineering machinery cables and other places, the application field is also expanding.

Development of fluorine-containing plastic cables:

One type of composite film wrapping wire: PFA/PTFE, FEP/PTFE, FEP/P1 composite film wrapping wire, widely used in the aviation industry.

Irradiation-related ETFE is cross-linked by irradiation, which increases the strength and radiation resistance, and makes the use temperature reach 200°C. Due to its light weight, high strength and radiation resistance, it is widely used in nuclear industry, aerospace industry and radiation exposure environment. has been widely applied.

Microporous PTFE film wrapped wire, coaxial cable Microporous PTFE push coaxial cable foam FEP, PFA coaxial cable are widely used in various low-loss cables, phase-stable cables in phase-controlled radars, wires for early warning machines, etc. .

At present, the most widely used fluoroplastic cables are: RG178; RG179; RG316, etc.

At present, all countries in the world have set the development of 5G technology as a strategic development goal. With the blessing of 5G, "artificial intelligence" and "virtual reality" will greatly increase the computing and data transmission rates. With the development of communication technology, it is the semiconductor industry. In addition to being used as raw materials, the role of fluoroplastic products in the semiconductor industry is also irreplaceable. For example, some time ago, scientific The PFA announced by Mu announced a substantial expansion of production is worthy of attention. According to the plan, China will officially launch the commercial use of 5G mobile phones in 2020. In 2019, China will issue 5G temporary licenses in several cities to enable large-scale networking in some cities. Cities and hotspot areas are the first to realize it, and at the same time accelerate the industrialization process of terminals and network construction. The connecting cable used for 5G mobile phone radio frequency coaxial cable is called 5G mobile phone radio frequency connecting line, referred to as RF connecting line, as a signal The transmission line connection acts as a bridge for transmission. With the development of 5G, product updates are gradually speeding up. 5G mobile phones are products for terminal use, and radio frequency connection lines are products used in the early communication infrastructure construction. The special features of 5G mobile phones and radio frequency connection lines The relationship is like the relationship between a car and a road. Only by paving the road of communication infrastructure can we enter the application of 5G mobile phones and the Internet of Things. 5G radio frequency cables will drive the spring of fluoroplastics, wait and see.

For reference in Chinese :

https://mp.weixin.qq.com/s/qyYhH5_4_MZcD5xsfWKIwQ