“Teflon” is the trade name for “polytetrafluoroethylene” (ptfe), the chemical properties of Teflon. Other types of PTFE

Properties

Unit change

FPM/FKM
(Vuitton)

PTFE
(Teflon)

P.O.M.
+15%GF
+5%MoS2

dark grey

cream

rigidity

density

tensile strength

modulus of elasticity - (rupture)

70°C/24h 20% Deformation

permanent deformation pressure

100°C/24h 20% Deformation

recoil elasticity

wide tensile strength

abrasion/wear

Minimum temperature

Maximum temperature

NBR, TPU, MVQ,...

Elastomers- these are materials that, through the application of a small force, can be stretched very strongly. Due to their structure, elastomers have a very high degree of ability to return to their original position. This means that the permanent change in shape of these materials is negligible. In principle, elastomers can be divided into two groups: chemical cross-linking elastomers and thermoplastic elastomers. Chemically cross-linked elastomers or rubber materials are high polymers whose macromolecules are cross-linked in large loops by the addition of a vulcanizing agent. Thanks to such chemical cross-linking, they do not melt and disintegrate at high temperatures. Moreover, such cross-linking ensures that the rubber materials are insoluble and, depending on the environment, swell or contract less or more strongly. Thermoplastic elastomers are materials that have characteristic properties elastomers within a high temperature range. However, their cross-linking occurs physically, not chemically. Thanks to this, they melt at high temperatures and can be processed using conventional thermoplastic methods. Thermoplastic elastomers are soluble and have lower swelling properties compared to their chemically cross-linked equivalents.

POM, PA, PTFE + filler, PEEK, ...

Thermoplastics- these are melting high-polymer materials, which in their temperature range of application are much harder and more rigid compared to elastomers. Depending on its chemical composition, the properties of a material can be either brittle and brittle, or viscous and elastic. The morphological composition causes large stretches without returning to the original shape. The shape of the material changes plastically and thus the material is called plastomer. Plastomers are used in sealing technology for solid sealing elements such as support, guide and drive rings.

TPU (green) is a material from the group of thermoplastic polyurethane elastomers. TPU is characterized by particular wear resistance, excellent mechanical properties, extremely low permanent deformation pressure and high tear resistance. In seal technology, TPU is mainly used in the form of sponge rings, wipers, compact seals and chevron seals. The extrusion strength of TPU is far superior to that of rubber plastomers. TPU is suitable for use in special areas such as mineral oils, water and maximum temperature up to 40°C and in biodegradable hydraulic fluids at 60°C. Without back-up rings, TPU seals apply up to a maximum pressure of 400 bar, depending on the profile geometry.

TPU (red) is a hydrolysis-resistant thermoplastic polyurethane elastomer. It combines approximately the same mechanical properties of TPU and high stability, unusual for polyurethanes, in hydrolysis environments (with water temperatures up to 90 ° C) and mineral oils. These properties allow application in water hydraulics, tunnel construction, mining and press manufacturing. The gas permeability of TPU (red) is much lower compared to TPU (green), so it is especially used in high pressure gases.

CPU (red) is a molded elastomer produced using a special injection molding process from the same raw materials as TPU (red). It has the same chemical and mechanical properties as TPU (green), but is used for semi-finished products in sizes from 550 mm to 2000 mm and special sizes with extremely thick walls.

TPU (blue)- This is a modified TPU for use at low temperatures. TPU (blue), unlike the TPU (green) material, goes into a state of fluidity at a lower temperature (-42°C) and has higher elasticity and residual deformation (45%). Suitable for use in cold climates (-50°C).

TPU (gray)- This is a completely new thermoplastic polyurethane elastomer, with additives of composite materials that provide constant lubrication. This ensures a constant reduction in friction, increased sliding speed and reduced wear. Used for operation in conditions of poor lubrication (dry running), or lack of oil lubrication: water hydraulics and pneumatics (without oil).

NBR (black) is an elastomer based on cross-linked sulfur acrylic-nitrile-butadiene rubber. It has high hardness and, for rubber elastomers, high abrasion resistance. At high temperatures, especially in an oxygen environment (air 80°C), aging accelerates, the material becomes hard and brittle. When air access is blocked, the aging process slows down significantly. Due to its unsaturated structure, NBR has low resistance to ozone, weathering and aging. Swelling in mineral oils is negligible, but is highly dependent on the composition of the oil. Gas permeability is relatively high, as a result of which there is a danger of explosive decompression, in which parts of the material rupture. It is used in areas where, in addition to high resistance to fuel and mineral oils, high elasticity and permanent deformation are also required (cylinder seals at low pressures).

H-NBR (black)- this is hydrogenated acrylic-nitrile-butadiene rubber and has, compared to NBR, better mechanical properties, high resistance in chemical environments such as propane, butane, mineral oils and fats, with a high percentage of additives, in dissolved acids and alkalis at a wider temperature range (-25°C to +150°C). Also more resistant to ozone, weather and aging. At the same time, it remains highly elastic. Used in engine and gearbox seals, crude oil and natural gas production, etc.

FPM, FKM (brown)- elastomer based on fluoro-rubber cross-linked with bisphenol (Viton - Du Pont trademark). Designed for groove rings, wipers, sponge rings, chevron seals, etc. Highly resistant to temperatures, chemicals, extreme weather conditions and ozone. Temperature range: from -20°C to + 200°C (short-term up to 230°C). Used in hydraulic systems with highly flammable liquids of the HFD group (phosphorus based). Low resistance to ammonia and ammine environments, polar solvents (acetone, methylethylketone, dioxane), and glycol-based brake fluids.

EPDM (black)- an elastomer based on peroxide-crosslinked ethylene-propylene-diene rubber. It has good mechanical properties and a wide temperature range of application: from - 50°C to + 150°C, hot steam up to 180°C. Due to its non-polarity, it is not stable in hydraulic fluids based on mineral oils and carbohydrates. Used in conditions hot water, steam, alkalis and polar solvents (in washing and cleaning equipment). When used in brake fluids based on glucol, compliance with regional regulations is required. Resistant to weather, ozone and aging.

MVQ (brown) is an elastomer based on methyl vinyl silicone rubber. Free of soot and suitable for electrical insulation. Temperature range from - 60°С to +200°С. Used for O-rings, flat and special seals, in the food and chemical industries. Due to its low mechanical values (compared to other rubber materials) it is used primarily in static seals. Swelling in mineral oils is negligible, but depends on the composition of the oil.

PTFE (white) is a crystalline thermoplastic based on the chemical basis of polytetrafluoroethylene (Teflon). An exceptionally wide temperature range of application (-200°C to +200°C), the lowest coefficient of friction (m=0.1) among all plastic materials and a very high degree of resistance to almost all environments. PTFE has a non-stick surface, does not absorb moisture and has very good electrical properties. It is important to take into account the time-dependent plastic deformation of PTFE even under light load (cold flow). Resistant to almost all chemicals except elemental fluorine, chlorotrifluoride and molten alkali metals. Therefore it has the most wide range applications in technology.

PTFE + filler (gray)- differs from PTFE in its own way chemical composition added fillers (15% glass fiber and 5% molybdenum disulfide), which reduce plastic deformation under load (reduced cold flow, increased extrusion resistance). It is used in sealing elements for low friction with high loads, for sliding and supporting elements, where pure Teflon cannot be used. Due to the presence of fillers, it cannot be used in the food industry.

POM (black)- technical thermoplastic based on polyacetal (polyoxymethylene). It has a high ability to retain shape, high surface resistance, elasticity and low moisture absorption. The tendency to cold flow at temperatures below 80°C is insignificant. POM is an excellent material under sliding and wear conditions and has excellent mechanical properties. POM is used where high hardness and low friction are required, that is, for guides and support elements (at T = 100°C). Not stable enough in acids and alkalis.

PA (black)- thermoplastic based on cast polyamide. Used instead of POM for diameters greater than 250 mm. High ability to retain shape, elasticity and rigidity, but prone to moisture absorption (loss of rigidity and change in volume). Use in watery environments is not recommended. Well suited for sliding operation (support, guide rings).

PEEK (cream)- thermoplastic based on polyaryletherketone from a number of highly temperature-resistant artificial materials. It is used mainly in those areas where, due to high temperatures (up to +260°C), high chemical and mechanical requirements, the use of conventional technical plastic materials is impossible. Universal stability in many chemical environments (with the exception of sulfuric acid, saltpeter) determines the use of PEEK in the oil and gas and chemical industries. Widely used in electrical engineering and electronics due to its good electrical properties in combination with mechanical properties.

other types of POM-S, POM-G

PTFE TFM

PTFE TFM is the so-called second generation Teflon, obtained by modification with a small addition of PPVE, which affects the formation of the crystalline phase of the polymer. Significantly shorter molecular chains compared to standard PTFE and a modified crystal structure made it possible to combine certain thermoplastic properties of this modification with the general good mechanical properties of the basic form of PTFE. Modification of PPVE leads to the formation of smaller crystallites, distributed more uniformly and densely, which affects a more uniform structure of the polymer, manifested, in particular, by higher transparency of PTFE TFM compared to the main form. This makes it possible to improve properties of thermoplastics such as conductivity, fluidity and reduced porosity of the plastic.

PTFE TFM is also different:

better mechanical properties, such as: elongation at tension/break, rigidity - especially at high temperatures
significantly less deformation under load and greater ability to return to its original shape after the load is removed
less creep, especially in the range of higher temperatures and/or loads
higher transparency and very smooth surface
welding capability

Application area of PTFE TFM
PTFE TFM is used in the construction of machine and equipment elements that require high survivability of elements, for example, in elements operating with short breaks or service elements over long time ranges. It is used in devices for which high operational reliability and availability are expected, as well as for elements requiring welded connections.

PTFE+ GF

PTFE + GF- is a modification containing the addition of 15 or 25% glass fiber

PTFE + GF different

higher resistance to compression (less susceptibility to creep)
greater dimensional stability
superior resistance to abrasive wear (the addition of GF, however, causes faster wear of the element interacting in pairs).
better thermal conductivity
conditional chemical resistance in contact with alkanals, acids and organic solvents
good dielectric properties

Application area of PTFE+GF
The modification is used in the production of fittings for making cone-shaped valves, the valve support surface, in electrical engineering electrical insulators are made from it, and in sliding pairs it is used as a bearing element.

PTFE+C

PTFE + C - is a modification containing the addition of 25% carbon.

PTFE+C is different

very high hardness and resistance to compressive loads
good sliding properties and resistance to abrasion wear, also in the case of dry friction
good thermal conductivity
low resistance to electrical breakdown and low surface active resistance
lower chemical resistance in contact with working fluids with oxidizing properties

PTFE+CF

PTFE + CF- is a modification containing the addition of 25% carbon.

PTFE+CF is different

very little creep
good resistance to abrasive wear, also in aqueous environments
significantly reduced electrical resistance
very good chemical resistance
higher thermal conductivity and lower thermal elongation (also compared to the modification with fiberglass)

Application area of PTFE + CF
The modification is used in the production of machine elements that require removal of electrostatic charge. In the design of chemical devices, it is used to make sliding bearings, housings and valve seats. Other applications include: tight piston guides running without lubrication, various seals, sliding and O-rings subject to abrasive wear during dry operation. The modification is used primarily for the production of sliding bearings and other elements that work with friction.

PTFE + graphite

PTFE + graphite - is a modification containing the addition of 15% graphite.

PTFE + graphite is different

good sliding properties and low coefficient of friction (less than in the case of PTFE + C)
better thermal and electrical conductivity
less chemical resistance in contact with oxidizing agents
relatively high abrasive wear when working in tandem with elements made of metal

Application area PTFE + graphite
The modification is used primarily for the production of slip films that allow the removal of electrostatic charges.

PTFE + bronze

PTFE + bronze - is a modification containing the addition of 60% bronze.

PTFE + bronze is different

good sliding properties and high resistance to abrasive wear - practically the lowest wear among all PTFE modifications
slight creep
good thermal conductivity, allowing to lower the temperature of interacting elements and thereby increase their survivability
limited chemical resistance in contact with acids and water

Application area PTFE + bronze:
The modification is used in the design of machines for the production of bearings and sliding guides subjected to high mechanical loads and guide rings in hydraulic cylinders.

Detailed information on non-standard modifications is provided by Plastics Group specialists.

STORAGE
It is best in boxes or on pallets, paying attention to the flatness of the warehouse surface - uneven surfaces can cause irreversible deformation (bending) of stored semi-products.
When storing (for example, slabs) in stacks, attention should be paid to the susceptibility of PTFE to fluidity - storage should be avoided large quantity slabs in one stack ( heavy weight) and other possible threats that may cause deformation of intermediate products.

Fluoroplastics are a class of polymers and copolymers based on fluorine. The discovery of the material occurred by accident in 1938, when the American Roy J. Plunkett was studying the properties of a new refrigerant, chlorofluorocarbon. One day he discovered an unknown gas on the walls of canisters with gas pumped under high pressure. White powder. Reasoning that this was a polymerization product, he decided to investigate the properties of the new substance. These properties turned out to be so extraordinary that the DuPont company patented it in 1941 under the name “Teflon” and began to look for practical applications for it.

In 1947, work began on the production of a domestic analogue - fluoroplastic.

Properties

— White material, slippery and smooth to the touch, similar in appearance to paraffin or polyethylene. Refractory, non-flammable, heat- and frost-resistant, retains elasticity in the temperature range from -70 to +270 °C. Transparent fluoroplastic is also available, but it is less heat-resistant, usually withstanding heating up to 120 ° C.
- Has high electrical resistance, an excellent dielectric and insulating material.
— It is characterized by revolutionary low adhesion (adhesion) - so much so that special technologies had to be developed to ensure reliable bonding of the Teflon coating to other surfaces.
— The coefficient of friction and slip is extremely low, which makes it popular lubricant.
— It is not afraid of light and does not transmit UV radiation, does not swell in water, and is not wetted by liquids, including oils.
— Fluoroplastics are well processed; they are cast, rolled, drilled, ground, and pressed.
— Inert towards human tissues, therefore suitable for the manufacture of implants, for example, heart valves, prostheses, artificial vessels.

Fluoroplastics are resistant to the most concentrated acids and alkalis, do not react with acetone, alcohol, ether, and are not susceptible to the destructive effects of enzymes, mold and fungi. In terms of chemical resistance, they surpass all known polymers and even metals such as gold and platinum. They are destroyed only by fluorine, fluorine fluoride and molten alkali metals.

At temperatures above 270 °C they begin to decompose, releasing, among other substances, very poisonous perfluoroisobutylene gas. Teflon and Teflon-coated cookware are safe as long as they are not overheated or burned. Coating particles that get into food are not digested and are excreted unchanged through the intestines.

The disadvantage of fluoroplastic is its fluidity, due to which it cannot be used pure form Use under load and for large structural forms.

Application

Fluoroplastic found wide application in different areas. They are produced in the form of powder, aqueous solution (a mixture of fluoroplastic dust with water), thin film, pressed blanks, which are converted into parts of devices and machines by mechanical processing.

Fluoroplastic is used in military, aviation, space technology, electrical engineering and radio electronics, and mechanical engineering. In electrical engineering and radio electronics, they are used to make insulating materials; in machines and machine tools - bearings, gaskets, washers and other friction units, as well as parts of complex structures. Finely dispersed fluoroplastic is added to lubricants. Many parts and surfaces are coated with a thin layer of a substance to protect against corrosion.

In the chemical industry it is used for the production of containers, pipeline coatings, hoses, parts resistant to aggressive environments, low and high temperatures, high blood pressure.

Fluoroplastics are used in textile production to produce fabrics with dirt- and water-repellent properties, heat-resistant, wear-resistant, and non-absorbent odors.

In medicine, prostheses and implants are made from this polymer.

It is used on conveyor belts for the production of foam plastic in the construction industry.

In the food industry, baking trays, molds, ovens, waffle irons, grills, coffee makers, and Teflon-coated utensils are very popular.

Teflon can be found in everyday life on dishes with non-stick and anti-stick coatings, on razor blades (to increase their service life), on plates for irons and on ironing boards, in bread machines, coffee pots, and in heating appliances.

It is used in entomology when keeping flightless insects - they cannot climb the smooth fluoroplastic walls of the house, that is, they cannot escape.

Through the Prime Chemicals Group online store you can order fluoroplastic chemical glassware, funnels and reactor containers made of high-quality fluoroplastic.

Polytetrafluoroethylene, (-CF 2 CF 2 -) n - a polymerization product of tetrafluoroethylene, a polymer with a unique combination of physical, electrical, antifriction, chemical and other properties that cannot be found in any other material, as well as the ability to maintain these properties over a wide temperature range: from - 269 o C to +260 o C.

Polytetrafluoroethylene (PTFE, PTFE) was discovered on April 6, 1938 by Roy Plunkett, an employee of DuPont. While working with freons, Plunkett discovered a white powder on the walls of the cylinder containing tetrafluoroethylene gas. Further research revealed that this substance is a polymer - polytetrafluoroethylene, formed as a result of spontaneous polymerization of tetrafluoroethylene.

First pilot production PTFE was launched in the USA in 1943 by DuPont (the product was produced under the trade name Teflon), just six years after the opening of this fluoropolymer, and in England they began to produce it at ICI under license from DuPont at the end of 1947.

To the Soviet Union Teflon(Teflon) came with samples military equipment transferred under Lend-Lease. Due to the exceptional properties of this polymer, which make it possible to solve many problems in the military industry, in 1947 the USSR Government instructed three scientific organizations: NII-42, USSR Academy of Sciences and NIIPP to develop the synthesis of monomer and polymer, as well as methods for processing into domestic products PTFE.

In March 1949, at the State Institute of Chemical Chemistry ( State Institute applied chemistry) the first pilot plants for the synthesis of monomer and fluoropolymer were created PTFE, on which the technological process was tested. At the same time, NIIPP (later ONPO "Plastpolymer") was working on a new scientific and technical direction: "Recycling polytetrafluoroethylene into various products." In 1956, the first industrial production was put into operation at the Kirovo-Chepetsk Chemical Combine (KCHK) PTFE in Russia under the trademark fluoroplastic-4(F-4). Since 1961, KCCHK mastered the production of other fluorinated polymers and copolymers. Due to the growing need for fluoropolymers in 1963, additional production capacity was introduced at the Ural Chemical Plant fluoroplastics F-4 And F-4D

From 1950 to 1961, based on six monomers developed at GIPH, over 60 different fluorine-containing products were obtained at NIIPP, including homopolymers: fluoroplastic-1, fluoroplastic-2, fluoroplastic-3, fluoroplastic-4 and copolymers - fluoroplastic-23, fluoroplastic -32, fluoroplastic-30, fluoroplastic-40, fluoroplastic-4MB.
In 1961, the first production was launched (fluoroplastic-42, fluoroplastic-40).

In the 60s - 80s, the development and development of new brands continued PTFE and new species thermoplastic fluoropolymers(TPFP) and fluoroelastomers(FE).

Properties and application of fluoroplastic-4

Ftoroplast-4- a high molecular weight crystalline polymer with a melting point of about 327°C, above which the crystalline structure disappears and it turns into an amorphous transparent material that does not transform from a highly elastic to a viscous flow state even at decomposition temperatures (above 415°C). The viscosity of the polytetrafluoroethylene melt at 380°C is 10 10 -10 11 Pa*s, which excludes the processing of this polymer by methods usual for thermoplastics. In this regard, fluoroplastic-4 is processed into products by the method of pre-molding the workpiece in the cold and its subsequent sintering.

Foreign analogues fluoroplastic-4: ALGOFLON ® PTFE F (Solvay Plastics), Teflon ® 7 (DuPont), HOSTAFLON ® TF 1702 (3M/Dyneon), POLYFLON ® M 12, 14 (Daikin Industries Inc.), Fluon ® PTFE G 163, 190 (Asahi Glass Co.,Ltd.)

Ftoroplast-4 has:

exceptionally high dielectric properties due to the non-polarity of the polymer;
low dielectric loss tangent values and dielectric constant, almost independent of frequency and temperature;
exceptionally high resistance to arc voltage;
electrical strength (when measured on thin films with a thickness of 5-20 microns, the electrical strength reaches 300 MV/m or more);
extremely high chemical resistance, which is explained by the high shielding effect of electronegative fluorine atoms;
resistance to all mineral and organic acids, alkalis, organic solvents, gases and other aggressive environments. Destruction of the polymer is observed only under the action of molten alkali metals, their solutions in ammonia, elemental fluorine and chlorine trifluoride at elevated temperatures;
the ability not to be wetted by water and not exposed to water during long-term tests;
absolute resistance in tropical conditions, fungal resistance;
high anti-friction properties, exceptionally low coefficient of friction (in certain conditions and pairs, the coefficient of friction is up to 0.02). This is explained by the small magnitude of intermolecular forces, which determine the insignificant attraction of other substances). The coefficient of friction decreases with increasing load and increases irreversibly by 2-3 times at 327°C and at 16-18°C after exposure to high speed.

Ftoroplast-4 with him low strength And thermal conductivity rarely used in its pure form in antifriction products operating under load (for example, bearings); For this purpose, filled compositions are created containing graphitized carbon, coke, fiberglass, molybdenum disulfide, or so-called metal fluoroplastic compositions that have increased hardness, wear resistance, and thermal conductivity. An alternative to PTFE, in some cases, can be harder and more durable fluoroplastics F-2, F-2M, F-3 or F-40.

DisadvantagePTFE is creep, increasing with increasing temperature. Already at specific loads of 2.95-4.9 MPa, noticeable residual deformation appears, and at pressures of 19.6-24.5 MPa and a temperature of 20°C, the material begins to flow. Deformation phenomenon polytetrafluoroethylene under load in the cold allows it to be used at a one-sided pressure of no higher than 0.295 MPa.

Optical properties PTFE low. It is transparent to visible light only at a thickness measured in tens of micrometers. For ultraviolet rays transparent within wavelengths of 200-400 microns, for infrared rays -2-75 microns. Many types of thermoplastic fluoropolymers have excellent optical properties.

Ftoroplast-4low resistance to radiation. Its mechanical properties quickly deteriorate under the influence of λ - and β - radiation. Already at a dose of 5*10 4 Gy, the destruction of the polymer is so deep that it becomes brittle and breaks when bent. Due to the insufficient radiation resistance of products made from PTFE cannot be operated for a long time in conditions of high levels of penetrating radiation. A replacement for the use of F-4 under radiation exposure can be hydrogen-containing fluoroplastics F-40 or PVDF.

Products from fluoroplastic-4 can be practically used in a very wide temperature range: from -269 °C to +260 °C. However When the temperature changes, the mechanical properties change sharply properties polymer (see properties table). Since hardening is gradually removed at elevated temperatures, hardened products are rarely used and mainly at low temperatures.

Due to its high heat, frost and chemical resistance, anti-friction, anti-adhesive and exceptional dielectric properties, fluoroplastic-4 is widely used:

How anti-corrosion material in the chemical industry for the manufacture of apparatus, elements of distillation columns, heat exchangers, pumps, pipes, valves, facing tiles, stuffing box packings, etc. The use of PTFE in chemical apparatus as pipes, seals, and gaskets contributes to the production of high-purity products;
How dielectric in electrical engineering, electronics. It is especially successfully used in high- and ultra-high-frequency technology. For example, oriented film is used for the manufacture of high-frequency cables, wires, capacitors, and coil insulation; for groove insulation of electrical machines, frames, insulators;
V mechanical engineering in a clean and filled form for the manufacture of machine and apparatus parts, bearings operating without lubrication in corrosive environments, in the form of compressor seals, etc.;
V production of adhesives and dyes for coatings of irons, skis, etc.;
in the food industry (lining rollers for rolling out dough, coating baking dishes, etc.);
in medicine (prostheses and grafts made of fabric and felt based on fluoroplastic fiber, tissue and blood vessel prostheses made from fluoroplastic-4 threads, implants and suture materials, containers for receiving coronary blood, holders for prosthetic mineral valves, etc.)

Ftoroplast-4A and -4AT- fluoroplastic-4 grades with free-flowing properties. The use of bulk grades in the manufacture of shaped products using the isostatic pressing method can significantly simplify the labor-intensive process of filling the mold and reduce the wall thickness of the finished products by 1.5-2 times.

Ftoroplast-4D- is a finely dispersed modification of polytetrafluoroethylene with a lower molecular weight than fluoroplastic-4, in its physical, mechanical and electrical characteristics it is close to fluoroplastic-4, in chemical resistance fluoroplast-4D surpasses all known materials, including gold and platinum; resistant to all mineral and organic acids, alkalis, organic solvents, oxidizers; is not wetted by water and does not swell, dielectric properties are almost independent of temperature, frequency and humidity. Ftoroplast-4D processed by the extrusion method, called "paste extrusion", into profile products (thin-walled pipes, insulation, thin film coatings) of unlimited length, which are difficult or impossible to obtain from conventional fluoroplastic-4. Based on fluoroplastic-4D, it is possible to prepare suspensions used for the manufacture of non-stick Teflon coatings by spraying or roller rolling, as well as for anti-corrosion, anti-friction and anti-adhesive protection of metals.

Products made from fluoroplastic-4D: FUM tape - intended for seals threaded connections at temperatures from -60°C to 150°C and a pressure of 65 atm., electrical insulating tubes - for insulating conductive parts of electrical products when working in aggressive environments, pipes, rods, etc. are manufactured using the frame extrusion (plunger extrusion) method.

Properties of fluoroplastic-4

Indicator name	Ftoroplast-4	Ftoroplast-4D
Physical properties
Density, kg/m 3	2120-2200	2190-2200
Melting temperature of crystallites, °C	327	326-328
Glass transition temperature, °C	-120	-119 to -121
Heat resistance according to Vicat, °C	110	-
Specific heat capacity, kJ/(kg*K)	1,04	1,04
Thermal conductivity coefficient, W/(m*K)	0,25	0,29
Temperature coefficient of linear expansion*10 -5 ,°С -1	8 - 25	8 - 25
Operating temperature, °C minimum maximum	-269 260	-269 260
Decomposition temperature, °C	more than 415	more than 415
Thermal stability, %	0.2 (420 °C, 3 h)	-
Flammability by oxygen index, %	95	95
Resistance to irradiation, Gy	(0,5-2)*10 4	(0,5-2)*10 4
Mechanical properties
Breaking tensile stress, MPa	14,7-34,5 15.7-30.9 (hardened samples)	12,7-31,8
Elongation at break, % relative residual	250-500 250-350	100-590 250-350
Modulus of elasticity, MPa when stretched when compressed with static bending at 20°C at -60°С	410 686,5 460,9-833,6 1294,5-2726,5	410 686,5 441-833,6 1370-2726
Breaking stress, MPa when compressed with static bending	11,8 10,7-13,7	11,8 10,7-13,7
Impact strength, kJ/m 2	125	125
Brinell hardness, MPa	29,4-39,2	29,4-39,2
Friction coefficient for steel	0,04	0,04
Machinability	Excellent	Excellent
Electrical properties
Specific volumetric electrical resistance, Ohm*m	10 15 -10 18	10 14 -10 18
Specific surface electrical resistance, Ohm	More than 1*10 17	More than 1*10 17
Dielectric loss tangent at 1 kHz at 1 MHz	(2-2,5)10 -4 (2-2,5)10 -4	(2-3)10 -4 (2-3)10 -4
The dielectric constant at 1 kHz at 1 MHz	1,9-2,1 1,9-2,1	1,9-2,2 1,9-2,2
Electric strength (sample thickness 4 mm), MV/m	25-27	25-27
Arc resistance, s	250-700 (a continuous conductive layer is not formed)

The general name “fluoroplastic” for a line of fluorine-containing polymers appeared in the middle of the last century in the USSR. The term is still used in Russian industry with number indices from “Ftoroplast-2” to “Ftoroplast-4”, but is not a registered or patented trademark.

Basic properties and industrial applications

Not only the technical name of the polymers “Ftoroplast” is similar, but also the properties and main characteristics of all its types:

infusibility;
inertia;
dielectric constant of fluoroplastic.

In different brands of fluoroplastic, these characteristics vary quantitatively, which leads to different possibilities for using the material.

Three main brands of fluoroplastic:

The production of fluoroplastic parts is carried out in one of four ways:

cold pressing with further baking of the fluoroplastic product and finishing mechanical processing;
extrusion;
spraying;
reflow.

The use of “two” in industry stems from several parameters in which this type of fluoroplastic is superior to others:

high hardness, strength and rigidity (at temperatures up to 120 °C);
resistance to water, solvents, radiation of any kind;
biological inertness - does not react with food and living organic material;
practically non-flammable;
chemically pure material (there are no impurities that appear during the production of fluoropolymers).

For fluoroplastic-2, the operating temperature is to = 150 °C; melting temperature of fluoroplastic-2 = 170 oC.

It is considered a universal material, used in all areas of activity, subject to limited heating.

Process of creating PVDF

As a result of laboratory research, several technological processes to obtain fluoroplastic-2. Based on profitability and yield criteria finished product, three chains are used in industry, differing in initiators and cost/quality balance

Properties of PVDF crystalline phases

Fluoroplastic-2 has four types of crystalline phases that can transform from one to another under external influences:

α-phase. Formed from a melt without the use of pressure or from other varieties during annealing.
β-phase. Formed from a melt under a pressure of 350 MPa. It is of particular interest, since in this phase the material exhibits piezo- and pyroelectric effects.
γ phase. Formed from a superheated melt. Unstable. Under mechanical influence (deformation of the sample) it passes into the β-phase.
δ-phase. Formed from the α phase when exposed to an electric field. By annealing a sample in the δ phase, subject to certain conditions, one can obtain any of the other three varieties.

Manufacturers and applications

Currently, fluoroplastic-2 is not produced in Russia. Leading foreign suppliers: Agru (Austria), FIP Spa (Italy), Georg Fischer (Switzerland), Simona (Germany), Glynwed Pipe SYSTEMS LTD.

Pipes and pipeline assemblies (taps, fittings) for pumping aggressive media or for the production of highly pure materials are made from fluoroplastic-2.

Sheet F-2 is used for lining containers and walls of premises.

Finished products made from fluoroplastic-2, as well as rods or sheets, are imported to Russia.

Current Western sanctions have recently reduced purchasing opportunities.

Ftoroplast-3 (F-3, F-3B, PCTFE)

It has dual characteristics - at temperatures up to 50 °C it is an amorphous mass; when heated, it crystallizes and turns into a polymer crystal with physical and chemical properties different from those of the amorphous phase, depending on the percentage of the crystal and the amorphous substance. With further heating to 200 °C, the crystal melts; at 300 °C, the melt chars and decomposes.

Operating temperature range from -200 to +125 °C. The material is inert to all solvents and chemical media, but is unstable to radiation and has relatively low electrical insulating properties.

The listed features determined the use of fluoroplastic-3 in units operating in an aggressive environment, but with low physical load.

Polytrifluorochlorethylene films are used to protect the surfaces of working mechanisms from contact with processed products in the food industry, pharmaceuticals, and medicine. The sliding properties allow the use of such units without additional lubrication.

PCTFE creation process

Radiation method. Technologically complex, requires compliance with temperature conditions. Advantage: it is carried out at room temperature.

Suspension method. Simple, cost-effective, but the product is of average quality.

Emulsion method. More expensive than suspension, but the quality of the polymer is higher.

The technology for industrial production of PCTFE is poorly described in the popular literature.

Properties of PCTFE

The polymer is mainly used in the crystalline phase, which has undergone a quenching process.

The hardened polymer is transparent and can be used as inspection windows for containers with aggressive media. When heated to 200 °C, hardened fluoroplastic-3 loses its hardening, crystallizes and becomes cloudy. The disadvantage is that the low thermal conductivity of fluoroplastic makes it possible to harden parts no thicker than 3-4 mm.

The advantage is that the absorption of water vapor and the diffusion of any other gases through PCTFE is zero.

Type F-3B differs from F-3 in better transparency in the light and infrared ranges.

PCTFE production

In Russia, fluoroplastic-3 is produced by domestic factories, in accordance with GOST-13744 of 1987. Available on the market in powder form:

grade “A” - for compositions;
brand “B” - universal;
grade “B” - for pressing products from compositions.

Based on brand “B”, suspensions in alcohol are produced (type “C”), which are unstabilized (type “SK”) and stabilized (type “SV”).

Fluoroplastic-4 (PTFE)

Fluoroplast-4, or PTFE material, is the most versatile product presented in the line. The importance of the material for industry and the widespread use of the polymer led to the adoption in 1980 of a separate GOST 10007-80 “Fluoroplastic-4. Specifications (with Amendments No. 1, 2)".

Works in a wide temperature range, maintaining its properties. It is not wetted by water, solvents or fats. Has low coefficients of friction and adhesion. The chemical resistance of polytetrafluoroethylene exceeds the chemical resistance of gold.

This type of fluoroplastic can withstand temperatures from -200 to +270 °C. The melting point of fluoroplastic-4 is 320 oC.

A limitation in use is the relative softness of the polymer, so it is used in units with minimal physical stress.

The high temperature resistance of fluoroplastic-4 is used in high-temperature pipelines; it is used to make insulation for high-voltage wires, technical fabrics and filters for various purposes. F-4 gaskets with fillers are installed in bearings designed to operate in aggressive environments or without the possibility of lubrication.

In everyday life, it is known to plumbers and gas workers as FUM tape, and housewives use frying pans with a non-stick coating made of fluoroplastic-4, called in this case “Teflon”.

Teflon

This is a patented name for fluoroplastic-4, and the properties of Teflon are the same as the properties of the F-4 brand of polymer. The high hardness of the material and its inertness determined the use of raw materials in kitchenware.

Mass distribution in everyday life places high hygienic properties on Teflon. Animal studies to determine why Teflon is harmful revealed an aggressive component and proved that the material is safe during normal use of non-stick products. Conversations that Teflon is harmful to health arose due to violations of the terms of use. Indeed, if the cookware overheats, for example, if you leave a frying pan on the fire unattended, the product heats up to dangerous temperatures and the Teflon coating is destroyed, releasing toxic components. These fumes are especially poisonous for birds, which die almost instantly.

The main competitor for Teflon-coated cookware is ceramic cookware. In most of the parameters compared, ceramics are better than Teflon. Except for one important thing - its price is much higher.

PTFE Creation Process

In Russia, two-stage technology is used in the production of fluoroplastic-4. At the first stage, chlorine atoms in the base substance are replaced with fluorine atoms, at the second stage heat treatment is carried out, and at the final stage the finished product is polymerized.

PTFE Specifications

The viscosity parameters of fluoroplastic-4 exclude hot stamping of products. The future part is formed in a cold way and then baked.

The polymer has “fluoroplastic-4” specifications begin with the epithet “exceptional”:

exceptional dielectric properties;
exceptional resistance to arc voltage;
exceptionally low dielectric loss tangent over a wide frequency range;
high chemical resistance;
absolute resistance in tropical conditions and salt fog;
exceptionally low coefficient of friction.

The density of PTFE fluoroplastic depends on the percentage of crystallization and ranges from 2.12 to 2.28 g/cm 3 .

Another external factor affecting the density of fluoroplastic is temperature. As it increases, the density decreases to a value of 1.53 g/cm 3 .

For comparison, under normal conditions the density of caprolon = 1.14 g/cm 3 .

The disadvantages of PTFE material include low strength, low transparency and deterioration due to radiation.

Application of PTFE

It is used wherever anti-corrosion properties and inertia of components are required, but there is no large mechanical load. In medicine, equipment and prosthetic elements are manufactured, including artificial vessels, implants, and blood collection containers.

Varieties of fluoroplastic-4

F-4A and F-4T in powder form are used for the manufacture of parts by pressing.

F-4D in the form of an especially fine powder with enhanced chemical resistance properties.

In international notation, F-4 is called “Teflon”. The use of Teflon as a material for non-stick coating of kitchen utensils is the most known use fluoroplastic-4 under this name.

Composite fluoroplastics

These are polymers to which filler was added during manufacturing.

Various fillers are used, depending on what properties of the base polymer need to be enhanced. Technical specifications the use of coal (coke), carbon fiber, molybdenum, and cobalt in additives is provided.

Additive picture

Fluoroplastic with coke, or black fluoroplastic, has a unique wear resistance, 600 times higher than that of the base polymer F-4. Graphite-filled fluoroplastic composite material (black) is used in units with critical friction conditions and difficult access for maintenance.

Problems connecting fluoroplastic parts

The excellent properties of fluoroplastic in terms of resistance to aggressive environments, low wettability, and zero diffusion create problems when it is necessary to glue parts together. Methods were proposed with preliminary surface treatment, washing, drying and gluing with epoxy compounds. Tests showed the low strength of such an adhesive seam; the adhesive fell off the surface under load.

The solution for gluing fluoroplastic with fluoroplastic was found and patented in the USSR in 1977.

The method involves treating the prepared surface with liquid gold and heating the part to a temperature where the gold is reduced and diffuses into the polymer to a depth of 1 micron. The gold-plated surface is glued with a compound to another part.

It is possible to use platinum or silver instead of gold, but platinum reduces the strength of the weld, and silver is not resistant enough to aggressive environments.

The problem of how to glue fluoroplastic to metal, or polymer to fluoroplastic, has not yet been satisfactorily solved. Modern technologies They offer special adhesives, for example, FRAM-30, but the surface to be glued must first be etched with liquid sodium, and the quality of the seam is low.

Delivery range

Fluoroplastics intended for further processing are supplied in the form of rods, sheets, films, powders and suspensions. The websites of most dealers have built-in online calculators that calculate the mass of the ordered assortment, taking as a basis specific gravity fluoroplastic. You can approximately determine the weight of a fluoroplastic sheet at the rate of 2200 kg/1 m 3, that is, a sheet 1000 mm x 1000 mm x 10 mm will weigh 22 kg. For comparison, a similar sheet of caprolon will weigh about 15 kg.

The weight of a fluoroplastic rod with a length of 1000 mm and a diameter of 100 mm will be about 18 kg.

Comparison of fluoroplastic and caprolon

Caprolon, or polyamide-6, is similar in characteristics to fluoroplastic. The difference between caprolon and fluoroplastic is in the mechanical properties, but it is impossible to definitively answer which is stronger - fluoroplastic or caprolon. The latter is a little harder, less deformed and damaged under equal loads. But at the same time, its wear resistance during long-term use is lower than that of fluoroplastic.

The production of parts from caprolon requires higher precision, but technologically it is easier and cheaper to make a part from it by casting than by pressing and baking from fluoroplastic.

The melting temperatures of caprolon and fluoroplastic are almost twice as different. The first one melts at 220 °C, and for the second one this is the operating temperature.

If long-term operation with small mechanical loads is required, it is advisable to install a fluoroplastic part; if the mechanical loads are significant, then caprolon is better than fluoroplastic. When comparing which is better - fluoroplastic and caprolon, when manufacturing bushings, the parameters of manufacturability and strength are taken into account.

Fluoroplastic bushings are made with a tolerance slightly larger external size and a little less on the inside, by pressing the shaft there. When a shock load is applied to the shaft, the bushing loses its shape and must be replaced.

Caprolon bushings are rigid, withstand shock loads perfectly, do not lose their shape, but wear out quickly. Precision manufacturing accuracy and additional shock absorption of the assembly are required.

Replacing fluoroplastic

High characteristics make it difficult to replace fluoroplastic with other materials. You can decide what to replace fluoroplastic with due to limitations in the operational parameters of the unit. For example, low operating temperatures make it possible to replace fluoroplastic with caprolon without loss of reliability. Imported material TECAPET (polyethylene terephthalate) has recently appeared on the market, replacing caprolon. It is not yet produced in Russia.