Polyurethane

Approximate price of sheet fluoroplastic

The market price per kilogram of F-4 polytetrafluoroethylene sheet on average ranges from 450 to 577 rubles / kg. The cost of composites is slightly higher, so the cost of the F4K15M5 brand is approximately 697 rubles / kg, and the F4UV15 brand - 1319 rubles / kg.

Material weight depending on the size of the plates

The price of the exposed polymer is significantly higher, a sheet of 1x1500x1500mm, Teadit (Austria) will cost 555 euros per sheet, and the cost of 2x1500x1500mm will be 970 euros per sheet.

Fluorolone sheet has proven to be one of the most effective materials in many industries. And the creation of new composites on its basis makes it possible to carry out more and more complex technological tasks.

Polyurethane sheet: manufacturers, brands and prices

Today, both domestic and imported sheet material is presented on the Russian market (among the supplying countries - China, USA, Germany, Italy).

The most common domestic brands of PU are SKU-7L and SKU-PFL-100, which differ from each other in such characteristics as the Shore hardness of polyurethane, tear resistance, tensile strength and other characteristics.

As for the price, the following figures can be given for a general idea. A 500 × 500 × 5mm plate of the SKU-7L brand costs about 1000 rubles, and the SKU-PFL-100 brand - about 1200 rubles.

This article has listed only a few areas of application of the material. In fact, this list is much longer. Due to the fact that PU surpasses rubber, rubber and other materials in various properties, its use is more cost-effective than the use of other traditional materials.

Foamed PU (foam rubber)

It is a porous synthetic product gas-filled by 85-90% with inert gas. Depending on the production method, composition, it differs in the degree of elasticity. It can be both soft (foam rubber) and hard, which is almost not subject to deformation.

Widely demanded in industry, construction, two-component foamed polyurethane - polyurethane foam, which is formed by mixing two components. The reaction proceeds very quickly - within 5-10 seconds the polyurethane foam foams, then hardens. The result is a light mass with low thermal conductivity, which does not rot, does not support self-combustion, is not exposed to moisture, alkalis, organic solvents, weak acids. Foamed polyurethane foam is in great demand as insulation, sound insulation. Perfectly fills pores, thus preventing cold bridges from forming. It is used in a wide temperature range from -60 ° C to + 140 ° C, practically does not change its properties over time.

Manufacturing of polyurethane

PU is made by casting, pressing, extrusion, pouring on special equipment. The polyol and isocyanate included in the composition are products that are synthesized from petroleum.

The following types of elastomer are used on the industrial market:

• liquid, foamed (polystyrene, foam rubber);
• solid (sheet, rod, plate);
• sprayed (polyurea).

For the manufacture of solid PU, the technology of casting into molds under pressure or pouring a liquid molten mixture into open matrices without pressure is most often used. Rarely, to obtain solid PU, the technological process of extrusion (extrusion) is used.

Polyurethane sheet

Polyurethane sheet is a rectangular plate made of resilient elastic polymer. The quality of polyurethane sheets is regulated by TU 84-404-78.

Manufacturing methods of polyurethane sheets - pressing, extrusion (squeezing), casting.The surface of the polyurethane sheet, depending on the operational requirements, can have both anti-friction and anti-slip properties. Properties are determined by chemical composition, structural features.

Most often, sheets are produced with a width of 0.1 to 0.2 m, a length of 1 to 1.5 m, and a thickness of 20 to 300 mm. This size range can be changed at the request of the customer.

The most common injection molding polyurethane is SKU-PLF, SKU-7L.

Consider the physical and chemical characteristics of SKU-7L cast polyurethane:

• tensile strength - 30 MPa;
• the conditional stress when the specimen is stretched up to 100% is about 2 MPa;
• range of operating temperatures - from -50 ° C to 100 ° C;
• Shore hardness - 75-85 units;
• density of polyurethane - 1180 kg / m³;
• relative elongation - 450%.

The unique properties of PU sheet products (sheets, plates, plates), due to their durability, practicality, make them widely in demand in many industrial areas. So, for example, the following products are produced from PU sheet:

• construction industry - non-slip flooring; parts of facades that are resistant to vibration;
• design of machines, mechanisms - parts in contact with oils, tires, bushings;
• heavy industry - shock absorber parts, lining;
• light industry, for example footwear - shoe soles.

Basic properties

Physical and mechanical properties of polyurethane

PU elastomers have many valuable physical properties when compared to other materials:

• high values ​​of strength and tear resistance;
• good dielectric properties;
• swelling resistance in various solvents and oils;
• high elasticity at any index of hardness (from 40 to 97 Shore A units);
• radiation and ozone resistance;
• good indicators of reverse deformation;
• the ability to work at elevated pressure (up to 100 MPa);
• at constant dynamic load, the maximum upper operating temperature of this material is 120 ° C. Low temperature does not significantly affect the quality of polyurethane elastomers down to -70 ° C.

Chemical properties of polyurethane

Polyurethane plates are highly resistant to solvents and oils, and are used for handling petroleum and petroleum derivatives as well as lubricating oils. In addition, this material is resistant to salt and water mist, UV radiation.

However, experience shows that the polymer is rapidly destroyed when exposed to nitric acid, substances containing a significant percentage of chlorine, acetones, formic and phosphoric acids, and turpentine.

Among the disadvantages of the material, one can single out low resistance to alkalis at high temperatures, a significant dependence of physical properties on temperature changes.

Structural laminate

Unlike getinax (paper-based laminated plastic), textolite is a multilayer material based on cotton fabrics impregnated with an alcohol solution of phenol-formaldehyde or cresol-formaldehyde resin, made by hot pressing.

For each of the brands of textolite, fabrics of various densities and weaves are used. The nature of the weave affects the degree of tensile strength of the final material, toughness, and crack resistance.

As a rule, chiffon, calico, calico, belting are used for production. The process of obtaining textolite includes the preparation of an alcoholic solution of the resin, which is placed in a special bath, where it is maintained at a constant temperature of 30–40 ° C.

The fabric, previously fixed in the mandrel, is lowered into the bath, after which it is passed through the rollers. The result is a more even distribution of the resin solution, and the fabric is sent to dry. Drying at 120˚C removes excess moisture, alcohol, volatile phenol.

The dried fabric is cut, assembled into bags and loaded into a press, where they are first warmed up to a certain temperature, held and cooled under pressure.

The finished material is cut to create a straight edge line and, after technical control, is sent to the finished product warehouse.

The main advantages of the composite over conventional plastics are its high degree of heat resistance and strength.

Composite material is more elastic and wear-resistant than metal. In addition, it is easy to process, and products from it do not require coloring. Differs in fire safety, resistance to gasoline, technical oil and water. Non-toxic.

Technical characteristics and application of sheet fluoroplastic

The use of the material is based on its unique properties:

• inertness in relation to chemically aggressive media. Only melts or ammonia solutions of alkali metals, chlorine trifluoride and elemental fluorine can act on the polymer when the temperature rises;
• one of the lowest values ​​of the coefficient of friction;
• heat resistance: fluoroplastic can be used in the range of -269 ° to + 260 ° C. The upper temperature limit is associated with the loss of physicochemical, but not with a change in its chemical properties. Decomposition of the polymer occurs at a temperature of + 415 ° C;
• exceptional dielectric properties that are independent of frequency and temperature;
• incombustibility, can ignite only in oxygen;
• small specific gravity of fluoroplastic;
• durability - the service life can be up to 20 years.

Exceptional characteristics open up a wide range of uses. Polymer products are actively used in the chemical, electrochemical and food industries, in instrument making and mechanical engineering, and in medicine.

Due to its high chemical inertness, this material is used for the production of containers in which aggressive compounds are transported and stored, for the lining of chemical equipment.

The high temperature resistance and excellent dielectric properties of this polymer are used in the manufacture of parts for high-frequency technology.

The low value of the coefficient of friction of fluoroplastic contributes to an increase in the service life of bearings, seals in friction units of mechanisms, especially in conditions of deep vacuum, ultra-low temperatures, exposure to aggressive media.

The absence of harmful effects on the human body makes it possible to use the polymer in medicine. It serves as a material for prosthetics of blood vessels, the manufacture of heart valves, containers for the transport and storage of blood and serum. It is used in the manufacture of pharmaceutical packaging.

Fluoroplastic in the food industry is actively used for the production of non-stick coatings.

Not sure how to protect crops from the scorching sun, frost and insects? Spunbond covering material, regardless of weather conditions, will help to get an earlier harvest and reduce fertilization costs.

You will learn about the basic properties and variety of plexiglass or acrylic sheet from this article.

Rubber seals GOST 14896-84 (polyurethane) for hydraulic devices

IMPORTANT!!! Currently, cuffs of type 2 according to GOST 14896-84 are not produced and they are replaced with cuffs of the same size type 3 or cuffs made according to TU 38-1051725-86

Designation of cuffs according to GOST 14896-84

An example of a symbol for a hydraulic cuff type 1 for sealing the gap between a cylinder with a diameter of 32 mm and a rod with a diameter of 22 mm, according to GOST 14896-84: Cuff 1-32x22 GOST 14896-84.

Groups of rubber cuffs for hydraulic GOST 14896-84

!!!

ATTENTION. the catalog contains a short list of hydraulic cuffs in accordance with GOST 14896-84, for clarification, please contact the managers of our company by e-mail

Application

Polyurethane is widely used for the manufacture of sheet sealing materials, lip seals and O-rings, various bushings, rods, equipment parts and other structural materials, in the production of stuffing box packing, in the shoe industry and the production of workwear, for the manufacture of rollers and solid tires (for special equipment) as a material for lining and lining equipment and pipelines. Also, polyurethane is widely used in construction, both in the form of adhesives and a component of building mixtures, and in foamed form. The wider use of this material is hindered by the small temperature range of operation.

Peculiarities

Polymer material is produced in sheets and rods, but most often polyurethane sheet is in demand, which has certain properties:

• the material is resistant to the effects of certain acidic components and organic solvents, which is why it is used in printing houses for the manufacture of print rollers, as well as in the chemical industry, when storing certain types of aggressive chemicals;
• high hardness of the material allows it to be used as a replacement for sheet metal in areas where there are prolonged increased mechanical loads;
• the polymer is highly resistant to vibration;
• polyurethane products withstand high levels of pressure;
• the material has a low capacity for thermal conductivity, retaining its elasticity even at minus temperatures, in addition, it can withstand indicators up to + 110 ° C;
• the elastomer is resistant to oils and gasoline, as well as petroleum products;
• polyurethane sheet provides reliable electrical insulation and also protects against moisture;
• the polymer surface is resistant to fungi and mold, therefore the material is used in food and medical fields;
• any products made of this polymer can be subjected to multiple cycles of deformation, after which they again take their original shape without losing their properties;
• polyurethane has a high degree of wear resistance and is resistant to abrasion.

Polyurethane products have high chemical and technical characteristics and in their properties are significantly superior to metal, plastic and rubber.

It is especially necessary to highlight the thermal conductivity of a polyurethane material if we consider it as a heat-insulating product. The ability to conduct thermal energy in this elastomer depends on its porosity values, expressed in the density of the material. The range of possible density for various grades of polyurethane ranges from 30 kg / m3 to 290 kg / m3.

The degree of thermal conductivity of a material depends on its cellularity.

The level of thermal conductivity starts at 0.020 W / mxK and ends at 0.035 W / mxK.

As for the flammability of the elastomer, it belongs to the G2 class - this means an average degree of flammability. The most budgetary brands of polyurethane are classified as G4, which is already considered a combustible material. The ability to burn is explained by the presence of air molecules in low-density elastomer samples. If the manufacturers of polyurethane designate the flammability class G2, it means that the material contains flame retardant components, since there are no other methods to reduce the flammability of this polymer.

According to the degree of flammability, polyurethane is classified as B2 class, that is, to hardly flammable products.

In addition to its positive characteristics, polyurethane material also has a number of disadvantages:

• the material is subject to destruction under the influence of phosphoric and nitric acid, and is also unstable to the action of formic acid;
• polyurethane is unstable in an environment where there is a high concentration of chlorine or acetone compounds;
• the material is capable of collapsing under the influence of turpentine;
• under the influence of high temperature conditions in an alkaline medium, the elastomer begins to break down after a certain period of time;
• if polyurethane is used outside its operating temperature ranges, then the chemical and physical properties of the material change for the worse.

Elastomers of both domestic and foreign production are presented on the Russian market of polymer construction materials. Polyurethane is supplied to Russia by foreign manufacturers from Germany, Italy, America and China. As for domestic products, most often on sale there are polyurethane sheets of the SKU-PFL-100, TSKU-FE-4, SKU-7L, PTGF-1000, LUR-ST brands and so on.

The main brands of fluoroplastic and their application

In order to increase the degree of wear resistance, mechanical strength, thermal conductivity, radiation resistance, fillers are added to the polymer: coke, molybdenum disulfide, carbon fiber.

The addition of these chemical elements leads to the emergence of new composites and further expands the scope of the material.

Grades of some composites based on polytetrafluoroethylene and their properties

FAF - foil-clad fluoroplastic dielectrics serve as the basis for printed circuit boards in HF devices, as well as for electrical insulation of printed parts in receiving and transmitting devices. Characterized by:

• mechanical strength;
• radiation resistance;
• independence of parameters from environmental changes;
• temperature range of application: from -60 ° to + 250 ° С.

Sheets are produced with a thickness of 0.5 - 5 mm, a layer of copper foil - 0.005 mm.

The manufacturer produces sheet extruded fluoroplastic in the following sizes: plates with a thickness of 2.0 - 50mm, formats from 200 × 200mm to 1000 × 1000mm. Composite sheets are produced with a thickness of 5.0 - 50 mm. Possible deviations in dimensions are 10mm.

A large number of Russian manufacturers operate on the market: CJSC Ftoroplastnye Tekhnologii (Novosibirsk), LLC Formoplast (St. Petersburg), Perm company Polymer, LLC PromPolymer (Ufa). In addition, many companies sell fluorone made in China.

Advantages and disadvantages

Polyurethane foam is a modern building material that has a strong structure and thermal insulation properties. The area of ​​application of polyurethane foam is quite diverse and includes many industries such as building construction, aviation, automotive, toys and upholstered furniture.

The main positive aspects of the material can be indicated as follows:

• the material does not cause allergic reactions;
• fungus and mold do not form in it;
• resistant to temperature changes;
• easy to use;
• a wide range of activities;
• high rates of sound insulation.

PUF for furniture production does not represent a favorable habitat for insects

And also its main advantage is the ability to take various necessary forms, which is important in the manufacture of upholstery for furniture, seats and mattresses.

Despite the significant advantages, polyurethane foam also has negative aspects.

• The negative influence of ultraviolet radiation contributes to rapid wear. Plaster or paint can be used as protection.
• Polyurethane foam is a flame retardant material. A high temperature will not lead to a fire, however, the insulation may start to smolder. This process can be stopped when the material is cooled. Therefore, where the surface can begin to warm up, it is better to refuse to use polyurethane foam.

Manufacturers and prices

Russian companies - manufacturers of PCB: LLC Brafi, Kirelis, Montazhstroyelectro, PKF Sistema-Plast, Formoplast, Prompolymer and many others.

Estimated cost of grades A, B, PTK:

• 0.5 mm - 290-300 rubles / kg
• 1-1.5 mm - 290 rubles / kg
• 2.0-100 mm - 270 rubles / kg

The cost of the PT brand is 145–195 rubles / kg, depending on the thickness. For PCB sheet PTK, the price for a sheet of 0.5x830x1400 mm format, weighing 0.9 kg will be approximately 270 rubles.

All products made of the material, in addition to their excellent strength and dielectric characteristics, are distinguished by ease of use, durability and quiet operation. They can be given any desired shape using a drilling and grinding machine, the final products do not need to be painted.

All this makes it possible to successfully use this laminated structural material in a wide variety of industrial sectors.

Receiving and chemical structure

The developer of polyurethane is Otto Georg Wilhelm Bayer, a German chemist, one of the authors of the stepwise polymerization method.Industrial production of polyurethanes was imposed in Germany in the late 30s and early 40s of the last century. Since then, the technology for the production of these materials has taken a great leap forward in quality.

In terms of polymer chemistry, polyurethanes are synthetic heterochain polymers. Since its inception, many options for the composition of the polymer have been developed, but the common point is the presence in the composition of the so-called urethane groups

—N (H) —C (O) O—

Moreover, in place of hydrogen, the chain may include alkyls (CH3) or other groups.

In addition, other functional groups can be included in the composition of the material; it is also possible to create branched or even cross-linked polymers, which makes it possible to synthesize polyurethanes with a wide range of physical and mechanical properties.