PTFE is a kind of * * polymer of ethylene and tetrafluoroethylene. This resin is the most tough fluoropolymer, which can form a highly durable coating with excellent chemical resistance and can work continuously at 15℃. It can be injection molded, extruded or painted.
After Teflon coating, it has the following characteristics:
1. Non-stickiness:
Almost all substances do not adhere to Teflon coating. Very thin films also show good non-adhesion properties.
2. Heat resistance:
Teflon coating has excellent heat resistance and low temperature resistance. It can resist high temperature to 3℃ in a short time, and can be used continuously between 24℃ and 26℃ generally. It has obvious thermal stability, and it can work at freezing temperature without embrittlement and does not melt at high temperature.
3. Slippery:
Teflon coating has a low friction coefficient. The friction coefficient changes when the load slides, but the value is only between .5 and .15.
4. Moisture resistance:
The surface of Teflon coating is free from water and oil, and it is not easy to get solution during production operation. If a small amount of dirt is stuck, it can be removed by simple wiping. Short downtime, saving working hours and improving work efficiency.
5. Wear resistance:
Under high load, it has excellent wear resistance. Under a certain load, it has the dual advantages of wear resistance and non-adhesion
6. Corrosion resistance:
Teflon is hardly corroded by drugs and can protect parts from any kind of chemical corrosion. Polytetrafluoroethylene is a polymer of tetrafluoroethylene. The English abbreviation is PTFE. The trade name is "teflon". Known as the "king of plastics". The basic structure of PTFE is.-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-.PTFE is widely used in all kinds of products that need to resist acid, alkali and organic solvents. It is not toxic to people, but ammonium perfluorooctanoate (PFOA), one of the raw materials used in the production process, is considered to have carcinogenic effects. The relative molecular weight of PTFE is relatively large, ranging from hundreds of thousands to more than 1 million, usually millions (the degree of polymerization is in the order of 14, while polyethylene is only in 13). Generally, the crystallinity is 9 ~ 95% and the melting temperature is 327 ~ 342℃. CF2 units in PTFE molecules are arranged in zigzag shape. Because the radius of fluorine atoms is slightly larger than that of hydrogen, adjacent CF2 units cannot be completely trans-oriented, but form a spiral twisted chain, and fluorine atoms almost cover the surface of the whole polymer chain. This molecular structure explains the various properties of PTFE. When the temperature is lower than 19℃, 13/6 helix is formed; At 19℃, the phase change occurred, and the molecules were slightly untied, forming a 15/7 helix. It does not melt at the temperature of 25℃ and is not brittle at the ultra-low temperature of -26℃. PTFE is so smooth that even ice can't match it. Its insulation performance is particularly good, and a newspaper-thick film is enough to resist the high voltage of 15V V. Polytetrafluoroethylene is produced by free radical polymerization of tetrafluoroethylene. Industrial polymerization is carried out by stirring in the presence of a large amount of water to disperse the heat of reaction and facilitate the control of temperature. Polymerization is generally carried out at 4 ~ 8℃ and 3 ~ 26 kgf/cm2. Inorganic persulfate and organic peroxide can be used as initiators, and redox initiation system can also be used. The heat release per mole of tetrafluoroethylene is 171.38kJ. In dispersion polymerization, perfluoro surfactants, such as perfluorooctanoic acid or its salts, must be added. The application of PTFE can be formed by compression or extrusion; It can also be made into water dispersion for coating, impregnating or making fibers. Polytetrafluoroethylene is widely used as high and low temperature resistant and corrosion resistant material, insulating material and anti-sticking coating in industries such as atomic energy, aerospace, electronics, electricity, chemical industry, machinery, instruments, meters, architecture, textiles and food.
Edit the chemical properties and insulation of this section:
It is not affected by environment and frequency, the volume resistance can reach 118 ohm cm, the dielectric loss is small and the breakdown voltage is high.
High and low temperature resistance:
The influence on temperature has little change, and the temperature range is wide, and the usable temperature is -19~26℃.
Self-lubricating property:
It has the smallest friction coefficient among plastics and is an ideal oil-free lubricating material.
Surface non-stickiness:
None of the known solid materials can adhere to the surface, so it is a solid material with the smallest surface energy. Atmospheric aging resistance, radiation resistance and low permeability: long-term exposure to the atmosphere, the surface and performance remain unchanged
incombustibility:
oxygen limitation index is below 9.
Edit the physical properties of this paragraph. The mechanical properties of PTFE are soft. Has a very low surface energy. Polytetrafluoroethylene (F4,PTFE) has a series of excellent performance: high temperature resistance-long-term use temperature of 2~26 degrees, low temperature resistance-still soft at -1 degrees; Corrosion resistance-resistance to aqua regia and all organic solvents; Weather resistance-the best aging life in plastics; High lubrication-with the smallest friction coefficient (.4) in plastics; Non-sticky-has the smallest surface tension in solid materials and does not adhere to anything; Non-toxic-physiologically inert; Excellent electrical properties, it is an ideal C-class insulation material. PTFE materials are widely used in national defense, military industry, atomic energy, petroleum, radio, electric machinery, chemical industry and other important departments. Products: PTFE bars, pipes, plates and turning plates. Polytetrafluoroethylene is a polymer of tetrafluoroethylene. The English abbreviation is PTFE. The structural formula is. It was discovered in the late 193s and put into industrial production in the 194s. Properties PTFE has a relatively large molecular weight, ranging from hundreds of thousands to more than 1 million, usually millions (polymerization degree is in the order of 14, while polyethylene is only in the order of 13). Generally, the crystallinity is 9 ~ 95% and the melting temperature is 327 ~ 342℃. CF2 units in PTFE molecules are arranged in zigzag shape. Because the radius of fluorine atoms is slightly larger than that of hydrogen, adjacent CF2 units cannot be completely trans-oriented, but form a spiral twisted chain, and fluorine atoms almost cover the surface of the whole polymer chain. This molecular structure explains the various properties of PTFE. When the temperature is lower than 19℃, 13/6 helix is formed; At 19℃, the phase change occurred, and the molecules were slightly untied, forming a 15/7 helix. Although the fracture of carbon-carbon bonds and carbon-fluorine bonds in perfluorocarbons need to absorb energy of 346.94 kj/mol and 484.88kJ/mol respectively, the depolymerization of polytetrafluoroethylene to produce 1mol of tetrafluoroethylene only needs energy of 171.38kJ. Therefore, during pyrolysis at high temperature, PTFE is mainly depolymerized into tetrafluoroethylene. The weight loss rates (%) of PTFE at 26, 37 and 42℃ are 1×1-4, 4×1-3 and 9×1-2 per hour, respectively. It can be seen that PTFE can be used for a long time at 26℃. Due to the toxic by-products such as fluorophosgene and perfluoroisobutylene produced during pyrolysis, special attention should be paid to safety protection and prevention of PTFE from contact with open flames. Mechanical properties Its friction coefficient is very small, only 1/5 of that of polyethylene, which is an important feature of perfluorocarbon surface. Because the intermolecular force of fluorine-carbon chain is extremely low, PTFE is non-sticky. ● mechanical properties: tensile strength σ b (MPa): 2.7 ~ 27.5 elongation δ 5 (%): 25 ~ 35 impact toughness value αk (J/cm2): notched: ≥16.1; No gap: > 98.1 tensile elastic modulus (MPa): ≥ 3.92 hardness: 5 ~ 65d ● Thermal properties: thermal deformation temperature: 1.86 MPa: 55℃; .46MPa:12℃ Martin heat resistance temperature: 25℃ Continuous use temperature: 25℃ Combustibility: self-extinguishing PTFE maintains excellent mechanical properties in a wide temperature range of-196 ~ 26℃, and one of the characteristics of perfluorocarbon polymer is that it does not become brittle at low temperature. Chemical corrosion resistance and weatherability PTFE is hardly corroded by any chemical reagent except molten alkali metal. For example, when boiled in concentrated sulfuric acid, nitric acid, hydrochloric acid or even aqua regia, its weight and properties are unchanged, and it is almost insoluble in all solvents, but only slightly soluble in total alkanes (about .1g/1g) above 3℃. PTFE does not absorb moisture, does not burn, and is extremely stable to oxygen and ultraviolet rays, so it has excellent weather resistance. Electrical properties PTFE has low dielectric constant and dielectric loss in a wide frequency range, and high breakdown voltage, volume resistivity and arc resistance. Radiation resistance PTFE has poor radiation resistance (14 rad), which is degraded by high energy radiation, and the electrical and mechanical properties of the polymer are obviously reduced.
The unique performance of PTFE in this paragraph makes it widely used in chemical industry, petroleum, textile, food, paper making, medicine, electronics and machinery, and other industrial and marine operations.
1. application of polytetrafluoroethylene (PTFE) in buildings
PTFE building membrane materials, such as SOLUS series products produced by TACONIC, have been widely used in large-scale public facilities, such as the roof system of stadiums, airport halls, exhibition centers and platforms. Light weight, its weight is only a small part of traditional building materials
High-strength glass fiber is the highest strength among textile fabrics, and it is even stronger than steel wires with the same diameter
Different from most solid building materials, soft Solus products can be stretched into various dynamic arc shapes
The light transmission is uniform through the inner and outer surfaces, forming soft scattered light
Low maintenance is required within the service life of the fabric, and only a little cleaning work is needed. Because the surface of the woven fabric is not sticky and tight, the rain will wash away the dust.
The surface is completely inert, and the harsh environment, such as mold and acid rain, will not work on the surface of the woven fabric.
Weldability Each woven fabric frame will be welded together to form a large ceiling. The strength of the weld will be greater than that of the woven fabric itself < P > The service life is long, and the PTFE coated glass woven fabric has almost no degradation during its service life. At present, it is estimated that Solus woven fabric can be used for at least 25 years < P > to obtain Class A fire protection evaluation, while it still maintains strong light transmittance
2. Application of polytetrafluoroethylene (PTFE) in corrosion resistance < P > Due to the defects in corrosion resistance of rubber, glass, metal alloy and other materials, it is difficult to meet the harsh conditions of temperature, pressure and chemical media. With its excellent corrosion resistance, PTFE has become the main corrosion-resistant material in petroleum, chemical industry, textile and other industries. Its specific applications include: pipelines for transporting corrosive gases, exhaust pipes, steam pipes, high-pressure oil pipes for rolling mills, high, medium and low-pressure pipelines for aircraft hydraulic systems and cold-pressing systems, rectification columns, heat exchangers, liners for kettles, towers and tanks, valves and other chemical equipment. The performance of seals has a great influence on the efficiency and performance of the whole machinery and equipment. PTFE material has the characteristics of corrosion resistance, aging resistance, low friction coefficient, non-stickiness, wide temperature range and good elasticity, which makes it very suitable for manufacturing seals with high corrosion resistance and service temperature higher than 1℃. For example, seals of groove flanges of machines, heat exchangers, high-pressure vessels, large-diameter vessels, valves and pumps, seals of glass reaction pots, flat flanges and large-diameter flanges, seals of shafts, piston rods, valve rods, worm pumps and pull rods, etc. 2. Application of low friction performance of polytetrafluoroethylene (PTFE) in load. Because the friction part of some equipment is not suitable for lubrication, for example, when lubricating grease will be dissolved by solvent and fail, or products in paper, pharmaceutical, food, textile and other industrial fields need to avoid lubricating oil contamination, filled PTFE material becomes the most ideal material for oil-free lubrication (direct load bearing) of mechanical equipment parts. This is because the friction coefficient of this material is the lowest among known solid materials. Its specific uses include bearings for chemical equipment, paper-making machinery and agricultural machinery, as piston rings, machine tool guide rails and guide rings; In civil engineering, it is widely used as a supporting slider for bridges, tunnels, steel roof trusses, large chemical pipelines and storage tanks, as well as as as a bridge support and a bridge swivel.
3. Application of polytetrafluoroethylene (PTFE) in electronic and electrical fields
Due to its inherent low loss and low dielectric constant, PTFE can be made into enameled wires for micro-motors, thermocouples, control devices, etc. PTFE film is an ideal insulating material for manufacturing capacitors, radio insulating pads, insulated cables, motors and transformers, and it is also one of the indispensable materials for industrial electronic components such as aerospace. An oxygen sensor can be manufactured by using the selective permeability of fluoroplastic film, which has high permeability to oxygen and low permeability to water vapor. Microphones, speakers, robot parts, etc. can be manufactured by using the characteristics of polar charge deviation of fluoroplastics at high temperature and high pressure. Using its low refractive index, optical fiber can be manufactured.
4. Application of polytetrafluoroethylene (PTFE) in medical treatment
Expanded PTFE material is pure inert, has strong biological adaptability, does not cause rejection of the body, has no physiological side effects on the human body, can be disinfected by any method, and has a microporous structure, so it can be used in various rehabilitation solutions, including artificial blood vessels and patches for soft tissue regeneration and surgical suture for blood vessels, hearts, general surgery and plastic surgery.
5. Application of anti-sticking performance of polytetrafluoroethylene (PTFE)
PTFE material has the smallest surface tension among solid materials, does not adhere to any substance, and also has excellent characteristics of high and low temperature resistance, which makes it widely used in anti-sticking aspects such as manufacturing non-stick pans. Its anti-sticking process mainly includes two kinds: installing PTFE parts or sheets on the substrate, and putting PTFE coating or paint cloth compounded with glass on the substrate through thermal shrinkage. With the continuous development of material application technology, the three shortcomings of PTFE materials, such as cold fluidity, difficult welding and difficult melt processing, are gradually being overcome, thus making its application prospects in optics, electronics, medicine, petrochemical oil transportation and seepage prevention more broad.