Monolithic polyurethanes (GOST-14896 (22704)) are particularly heterochain polymers, the macromolecules of which contain unprotected and/or substituted urethane groups (—N(R)—C(O)O—) based on alkyls, aryls or acyls. Depending on the type of synthetic elastomer, they may also contain both simple and ester binders: urea, amide and others. Their presence ultimately shapes certain properties of a particular type of polyurethane, depending on GOST for the material. The main difference between the produced types of this polymer is the different degree of hardness, range of operating temperatures and specific scope of application.
Polyurethane (GOST): basic properties
Polyurethane (GOST-14896) has unique properties, including high strength and elasticity with significant resistance to abrasion and mechanical stress. Unlike rubber, a fire-resistant elastomer is characterized by slow aging, which provides it with several tens of times longer service life. Because of this, it is often called “eternal rubber.”
This polymer retains its original properties over a wide range of negative temperatures. For example, irreversible deterioration in the elasticity of polyurethane GOST-14896 84 occurs below –18+2/20С, and the appearance of brittleness occurs at –60+/-60С depending on humidity. Products made from this elastomer are non-toxic and have a low glass transition threshold. At the same time, the bond between the elastomer and metals is several times stronger compared to a similar rubber-to-metal bond.
Polyurethane (GOST): advantages
- Low degree of abrasive wear with low weight and density.
- Wide range of operating temperatures (from –70 0С to +150 0С) and operating pressure without residual deformation (up to 100 MPa).
- Resistance to tearing and dynamic loads is especially characteristic of polyurethane GOST-22704.
- Significant dielectric properties with high levels of absorption of mechanical influences, vibration and shaking.
- Chemical resistance with high elasticity.
Technical specifications Polyurethane foam
Introduction.
These technical specifications apply to polyurethane foam: hard, soft, foam rubber, high elasticity foam rubber, hard foam rubber, high rigidity foam rubber, special purpose foam rubber.
Polyurethane foam belongs to the group of gas-filled plastics and is a material of synthetic origin, formed as a result of the hardening of a foamed mixture of liquid polymers of polyol and polyisocyanate.
Polyurethane foam is a foamed elastic plastic with a predominantly open-cell structure.
Polyurethane foam is produced in the form of rectangular sheets, rolls, and blocks. There are acoustic, contour and liquid (spray foam) polyurethane foam.
The following main types of polyurethane foam are produced: standard, with increased rigidity, super-hard, increased softness, highly elastic, for fire duplication, for the manufacture of household sponges, highly colored, with antistatic properties.
Technical requirements.
Polyurethane foam must meet the requirements of these technical specifications and be manufactured in accordance with the technological process of the enterprise according to recipes and regulations approved in the prescribed manner.
The values of physical and mechanical properties of standard polyurethane foam must meet the following requirements:
- density from 16 to 55 kg/m3;
- compressive stress at 40% compression from 2 to 5.5 kPa;
- residual deformation at 70°C and 50% compression after 22 hours should not exceed 4.5%;
- rebound elasticity of at least 40%;
- relative elongation at break of at least 150%;
- tensile strength of at least 100 kPa.
When producing polyurethane foam in the form of blocks, their linear dimensions and deviations are pre-agreed with the customer (consumer).
When producing polyurethane foam in the form of sheets, deviations in dimensions in length and width in compressed form are allowed within ±3% and ±1% in uncompressed form. The thickness deviation, taking into account residual deformation, should be in the range from plus 1% to minus 5%.
The following appearance defects are allowed on the surface of polyurethane foam sheets with an area of 1 m2 and a thickness of up to 20 mm:
- up to three pieces of air inclusions with a diameter of up to 6 mm;
- no more than two pieces of through air holes with a diameter of up to 6 mm;
- no more than two through holes with gaps at the edges of up to 20 mm.
For the surface of sheets with a thickness of over 20 mm, the following defects are allowed on an area of 1 m2:
- up to four pieces of air inclusions with a diameter of up to 10 mm;
- no more than two pieces of through air holes with a diameter of up to 6 mm;
- no more than two through holes with gaps at the edges of up to 20 mm.
In sheets of polyurethane foam, breaks and cracks up to 50 mm in size are allowed in an amount of no more than one such defect per sheet. There should be no more than one sheet with a tear or crack in one package.
The side edges of polyurethane foam sheets may have roughness, irregularities no more than 12 mm deep and cracks up to 10 mm formed when removing the paper form.
It is acceptable to have local inhomogeneities in the cellular structure in the sheets - stains, schlierens, surface irregularities - stripes resulting from cutting.
For sheets of highly elastic polyurethane foam of all thicknesses, the following is allowed on a surface area of 1 m2:
- no more than two through holes with a diameter of 4 to 8 mm;
- the number of air inclusions is not limited.
Polyurethane foam can be painted in different colors during production.
As a result of exposure to ultraviolet radiation, during storage and operation of polyurethane foam, its top layer may turn yellow over time, and the original color may be distorted. These phenomena do not affect the physical and mechanical properties of the material.
Raw materials used in the production of polyurethane foam must meet the requirements of the standards that apply to them and have a quality document.
Polyurethane foam can be packaged in packs, rolls, in a polymer film bag using the bulk method, in bales and pressed bales.
Each package of polyurethane foam is marked on opposite sides with two labels, which must contain the following information:
- trademark of the manufacturer and its name;
- material designation;
- brand of polyurene foam;
- sheet size;
- number of sheets in the package;
- Net weight;
- date of manufacture;
- designation of these technical conditions.
Safety requirements.
Polyurethane foam is a low-toxic and low-hazard substance. The material is safe for humans and does not irritate the skin and mucous membranes.
Polyurethane foam is a dielectric and can become electrified during processing, as a result of which production equipment and personnel working with it must be protected from static electricity.
Polyurethane foam belongs to the group of flammable materials of medium flammability; its raw materials are flammable liquids. The ignition temperature of polyurethane foam is plus 225°C, the self-ignition temperature is plus 450°C.
It is prohibited to use polyurethane foam and products made from it near heat sources, open flames and near parts and structures above 150°C.
Environmental requirements.
During the production of polyurethane foam, no liquid or solid waste is generated into the environment. Polyurethane foam processing is a waste-free production.
Acceptance rules.
Acceptance of polyurethane foam is carried out in batches.
A batch is considered to be products of the same name and symbol, made from identical materials using the same technological process during one work shift and accompanied by a single quality document.
The quality document must contain the following information:
- trademark and name of the manufacturer;
- address of the manufacturer;
- name of the product and its symbol;
- batch number;
- sheet size;
- number of sheets in the package;
- Net weight;
- date of manufacture in the format day, month, year;
- designation of these technical conditions;
- mark of the technical control department of the enterprise.
Each batch is subjected to acceptance tests. Tests are carried out no less than 72 hours after production of polyurethane foam.
In case of unsatisfactory results of acceptance tests for any of the quality indicators, repeated tests are carried out on a double sample of samples from the same batch. The results of repeated tests are considered final and apply to the entire batch.
Transportation and storage.
Polyurethane foam should be stored in covered warehouses, protected from precipitation and soil moisture, away from sources of open fire and heating devices. When laying material in stacks, their height should not exceed 3 meters.
Polyurethane foam is transported by closed vehicles of any type, subject to compliance with the transportation rules in force for the selected type of transport.
Each package of packaged polyurethane foam must be marked with a handling sign: “Keep away from moisture.”
Manufacturer's warranty.
The manufacturer guarantees that polyurethane foam meets the requirements of these technical specifications, subject to the rules of storage, transportation and use.
The warranty period is 10 years from the date of manufacture. It is possible to use polyurethane foam after this period, but after checking its quality for compliance with the requirements of these technical conditions.
According to the technical specifications, you will be able to produce products, test and certify them, and submit them for approval to various structures, such as the Ministry of Industry and Trade, Metrology Centers, Laboratories, etc.
The technical conditions are transferred to you in full. They can be registered for you in Rosstandart. Amendments are allowed. All specifications are agreed upon with you before signing.
Polyurethanes (GOST): use of main grades
- Polyurethane SKU PFL-100M is used for the manufacture of parts intended for use under intense abrasive wear, including wet environments. A highly elastic polymer, characterized by a low degree of residual deformation during compression, is indispensable for the production of seals.
- Polyurethane GOST SKU-7L is used for the production of wear-resistant products that operate under conditions of exposure to oils, fuel oil and other petroleum products. It is often used as a raw material for stamped parts.
- Polyurethanes designated according to GOST SKU-6 and “Vibratan-6060” with high hardness and elasticity are used for the manufacture of elastic parts of mining equipment. Also, these elastomers are widely in demand in the machinery industry and shipbuilding.
- Sheet polyurethane “Vibratan-8000” with an operating temperature range from –60 0С to +120 0С is one of the most high-tech elastomers. It is used for the manufacture of impact-resistant components of lifting equipment.
- Sheet polyurethane GOST-14896 84 is used for the production of cuffs and seals, as well as various general-purpose parts.
In addition to the above synthetic elastomers, there are many other types of material that are widely in demand in various industries, at work and at home.
You can purchase polyurethane products of various standards at. If necessary, our specialists will ensure the production of a batch of unique products with specific parameters.
Polyurethane SKU-7L
What is polyurethane SKU-7L and where is it used? Polyurethane is an elastomer that is characterized by wear resistance, high strength, and in addition it is resistant to impact loads. The advantages of polyurethane include the ability to maintain highly elastic properties over a wide temperature range.Polyurethane SKU-7L TU 84 404 2008 is intended for the manufacture of parts exposed to abrasive substances (wear work) in grain and food storage facilities. Due to its resistance to lubricants, oil and their derivatives, it is widely used as seals for oil and oil media in moving and fixed joints, as well as in stamping production. It has excellent wear resistance, very good tensile strength and tear resistance and is used for the manufacture of elastic equipment elements in shipbuilding and mechanical engineering. For operation at positive temperatures. Operating temperature range from +10°C to +80°C. Products made of polyurethane perfectly withstand sudden atmospheric changes, are impact-resistant, durable in industrial use and have properties that are unattainable for conventional rubber: - elasticity (relative elongation at break is 2 times greater than that of rubber); — low abrasion (conditional wear resistance is 3 times higher than that of rubber); — high strength (exceeds the strength of rubber by 2.5 times); — high resistance to tearing and repeated deformation; — ability to work at high pressure (up to 105 MPa); — acid resistance and resistance to many solvents; — increased hardness (from 40 to 98 Shore units); — temperature range from -30°С to +80°С; — resistance to microorganisms and mold; — vibration resistance and oil and petrol resistance; — elasticity at low temperatures; — high dielectric properties; — ozone resistance; - water resistance. Main technical characteristics of SKU-7L:
| 30 | ||
| Relative elongation, not less | % | 370 |
| Residual elongation after rupture | % | 4 |
| Shore hardness, A | units | 76–86 |
| Tear resistance, no less | N/mm | 30 |
| Wear resistance | mm | 40 |
| Oil and petrol resistance | — | high |
| Operating temperature | hail WITH | -30 +80 |
| Water resistance | — | satisfaction |
Polyurethane brand SKU-7L in rods is supplied with diameters from 20mm to 450mm of various lengths. Polyurethane grades SKU-7L in sheets (plates) are supplied in thicknesses from 3mm to 115mm in various sizes. On request, it is possible to supply bushings, finished products from polyurethane grades SKU-7L or cladding (coating) of metal products, shafts, vessels. Potassium sulfate fertilizer.
