The development of modern science does not stand still. Together with it, already known materials are improved, and new ones appear. As a rule, the basis is...

Polyurethane. What kind of material is this, its properties and areas of application?

From Masterweb

20.10.2018 16:00

The development of modern science does not stand still. Together with it, already known materials are improved, and new ones appear. As a rule, synthetic polymers such as polyurethane are used as a basis. What kind of substances these are and what applications they have found in all areas of everyday life and production, we will find out a little later. Physical and technological characteristics allow their use even in the most critical industries: mechanical engineering, production of insulators and fasteners. Without them it is simply impossible to imagine a person’s daily life.

For a step forward

Despite constant developments, the urgent need for new high-quality materials remains very high. Modern life requires a huge variety of different substances: plastic and hard, tensile and durable. They must withstand stress, temperature changes, and aggressive use.

This need is forcing scientists to experiment with the synthesis of polymer compounds and the compatibility of inorganic and organic components in an attempt to obtain more versatile compounds. Polyurethane is such a polymer. It has a whole set of unique properties that have made it one of the most actively used in almost all spheres of life and production.

What kind of material is this: polyurethane?

First, it’s worth understanding in more detail the substance itself and why it is called thermoplastic.

This polymer compound combines the hardness of durable plastic and the plasticity of natural rubber. It appeared only in the middle of the last century, thanks to the efforts of scientists from the USA who were able to synthesize it. The physical characteristics of this material directly depend on the main component.

Basic raw materials

There are several types of raw materials from which polyurethane material is produced for the sole. These are polyesters and polyesters, as well as aliphatic isocyanate.

Now that we know what kind of material this is - polyurethane, we need to understand its possible compositions.

If polyether (propylene and ethylene oxide, isoprene) has a higher percentage of the substance as a base, then the final substance becomes more resistant to the hydrolysis process and also receives increased frost-resistant and wear-resistant characteristics.

Bases made of polyesters (linear products of phthalic acid) give the final substance the following characteristics:

increase in tensile strength;
increased wear resistance;
possibility of restoring the original shape.

For wheels, polyurethane material based on the latter component gains increased ultraviolet resistance and ductility, even at temperatures below zero.

The main method for producing this substance is casting from granulate. The final elastomer can be in two states: viscous liquid and solid. Solids can be either crystalline or amorphous (that is, have only short-range order in the atomic structure).

To lengthen and structure the chains, glycols, water, glycerol ether or castor oil are used. These reagents set the molecular weight for linear polyurethanes.

The catalyst for the formation of polyurethane can be tertiary amines, beryllium, iron, vanadium or copper compounds, as well as lead or tin naphthenates.

The main feature of the substance

Finished products made from polyurethane material (insoles, for example) have different final properties, which may vary for each area of its application. A key feature is the ability to set and adjust the necessary parameters at the initial stage of obtaining the material. This contributes to an ever-increasing expansion of the areas of its use.

If you do not pay attention to the predominant component that underlies thermoplastic polyurethane, the resulting material also has a whole set of general properties.

Key Features

Firstly, this substance has durability and endurance and holds its shape well. Secondly, its high strength under various deformations, such as stretching or bending, allows it to become indispensable in industries where the plasticity of the material comes to the fore. Thirdly, a good level of noise and vibration absorption makes polyurethane popular, for example, in mechanical engineering.

In addition, the substance can be painted, which does not affect the wear resistance parameters, since the paint is applied not only to the top layer, but paints the entire volume.

The temperature range of application of this elastomer ranges from -60 to +80 degrees Celsius.

Polyurethane, as a shoe sole material, is resistant to fats, microbes, bacteria, temperature changes, sea water, aging, and mechanical stress. To increase the overall strength of the material, it can be coated with a layer of reinforced fiberglass. Solutions of polyurethane in organic solvents are converted into various types of high-strength adhesives.

And one very nice bonus: this substance can be recycled.

Applications

The main areas of use of thermoplastic polyurethane are:

Automotive industry;
production of general consumer goods;
shoe industry;
manufacturing of sporting goods;
cable production.

In automobile and mechanical engineering, this substance is used for the production of handles, shock-absorbing chassis supports, mats, springs, visors, various toggle switches and insulators. In some cases, decorative parts of the car interior are made from it.

In consumer sectors, soles, insoles and other similar shoe components, umbrella tips, etc. are made from it.

Polyurethane in the footwear industry

Polyurethane found its main use in everyday life in the shoe industry. Due to its basic qualities (frost resistance, elasticity, strength, durability and resistance to constant mechanical stress), it makes excellent soles, especially for winter types of shoes. The ergonomics of this polymer are high along with antiseptic properties, which allows it to be used for the manufacture of insoles.

The production of goods for recreation and sports is also not complete without polyurethane. It is used to make wheels for roller skates, sports tires, bushings and gaskets, tips for skis, special sports boots for snowboarding and speed skating, wheels for skateboards, connecting elements and various fasteners.

Brief summary

Now that we know what kind of material this is - polyurethane, it’s worth summing up. So, this elastomer is one of the most commonly used compounds. It is distinguished by a number of excellent technological, physical, chemical and design characteristics, which ensure its use in many industries and industries.

All these characteristics make the material economically viable for mass production. At the same time, the costs of this process are quite modest, both financially and in terms of time.

As a lining material, polyurethane is used for winding power cables and decorative elements of car interiors, for roller skates and insoles. The ability to set the necessary characteristics at the manufacturing stage allows you to expand the scope of application of this polymer and makes them almost limitless.

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heterochain polymers containing unsubstituted and/or substituted urethane groups -N(R)-C(O)O- (R = H, alkyl, aryl or acyl). The number of urethane groups depends on the mol. P. mass and ratio of initial components. Depending on the nature of the latter, P. macromolecules may contain other functions. groups: ether and ester (polyester-urethanes), urea (polyurethane ureas), isocyanate-urate (polyurethane isocyanurates), amide (poly-amidourethanes), double bonds (polydienuretane), which, along with the urethane group, determine the complex of properties of polymers . Linear and mesh polymers are known, as well as urethane-containing interpenetrating polymer networks and functional urethane. oligomers.

Receipt. Basic traditional method of synthesis of P., used in the industry, is mutual. compounds containing isocyanate groups with bi- and polyfunctional. hydroxyl-containing derivatives.

With an equimolar ratio of two bifunctional. components of the synthesis, linear polymers are formed. However, obtaining polymers that do not contain cross-links is not possible due to the high reaction. ability of the isocyanate group in relation to any compound. and groups containing an active hydrogen atom (water in the components and the environment, urethane groups in the resulting chain). Therefore, the so-called linear polymers should be considered as weakly branched polymers.

Mesh P. are obtained as follows. cases: 1) at least one of the components of the synthesis has functionality of more than two (urethane cross-links are formed); 2) along with the two main components of the synthesis, extension and structuring agents are used (the structure of chemical cross-links is determined by the nature of the structuring agents: in the case of triodes, urethane groups are formed, in the presence of water, diamines - biuret, carboxyl-containing compounds - amide, sulfur - polysulfide); 3) functions are introduced into P. macromolecules during synthesis. groups containing an active hydrogen atom, e.g. urea, and use the isocyanate component in excess relative to the hydroxyl-containing one (biuret cross-links); 4) carry out cyclotrimerization of isocyanate groups in the presence. specific catalysts, resulting in the formation of a cross-linking unit - the isocyanurate cycle.

This is how polyurethane isocyanurates are obtained.

Less common is the synthesis of polychlorides from biochloroformates of glycols (low molecular weight or oligomeric) and diamines.

R-alkylene, oligomer residue; R"-alkylene, arylene The reaction rate is high; however, due to the release of HC1 and the need to use acceptors for its binding, the wide practical use of this method is limited. This method produces N-substituted polypeptides (for example, from piperazine), which differ higher heat and frost resistance than their unsubstituted analogues.

Substituted P. can also be obtained by acetylation of unsubstituted linear P. with acetic anhydride in solution (cat.-chlorine acid).

The synthesis is based on the so-called. Non-isocyanate P. are based on non-traditional urethane formation solutions. For example, polyoxypropylene hydroxyurethanes are obtained from propylene oxide oligomers containing terminal cyclocarbonate groups (mol. wt 800-2000) and aliphatic. diamines

In this way, P. is obtained with a fundamentally different structure with new properties (in this case, with increased resistance to alkalis and high temperatures) than traditional P. based on polyoxypropylene glycols.

Urethane-containing interpenetrating polymer networks (IPNs) are obtained from branched or reticulated polymers and polymerizing monomers or reactive oligomers. For example, mesh P. is first subjected to swelling in styrene or oligoether acrylate, and then to polymerization and (or) hardening. The properties of IPNs are non-additive to the properties of the individual polymers that make them up (see also Network polymers).

Functional urethane oligomers receive interaction. isocyanate-containing prepolymers (see below) with compounds HO—R"—f, where f is a functional group, e.g. epoxy, methacrylate, peroxide; R" is alkylene. For example, glycidol is used to synthesize oligurethane epoxides.

Such oligomers can be cured with the same hardeners as their analogues that do not contain urethane groups. Products for obtaining P. 1. Isocyanates: tolu-ylene diisocyanates (2,4- and 2,6-isomers or their mixture in a ratio of 65:35), 4,4"-diphenylmethane-, 1,5-naphthylene-, hexa- methylene diisocyanates, polyisocyanates, triphenylmethane triisocyanate, biurethisocyanate, isocyanurate isocyanates, 2,4-toluylene diisocyanate dimer, blocked isocyanates (see also Isocyanates). The listed diisocyanates are used for the synthesis of all types of polyurethane, polyisocyanates - for the production of rigid polyurethane foams and paint coatings, biuret - and isocyanurate isocyanates - the main base for the production of paint and varnish coatings, triphenylmethane triisocyanate - the base for cross-linking relatively low-molecular polymers containing terminal OH groups in two-pack adhesive compositions, blocking diisocyanates - in single-pack ones. The structure of the diisocyanate determines the speed urethane formation, strength indicators, light and radiation resistance, hardness P.

2. Hydroxyl-containing components: 1) oligoglycols - products (mol. wt 1000-5000) of homo- and copolymerization of THF, propylene and ethylene oxides (polyoxyalkylene glycols), divinyl, isoprene (oligodiene diols); 2) polyesters with terminal groups OH-linear polycondensation products of adipic, phthalic and other dicarbonate compounds with ethylene, propylene, butylene or other low molecular weight. glycols; branched polycondensation products listed. mixture and glycols with the addition of triols (glycerol, trimethylol-propane), polymerization products of e-caprolactone. The hydroxyl-containing component determines mainly. physical-mechanical complex St. P.

3. Chain elongation and structuring agents: 1) hydroxyl-containing agents - water, glycols, oxyethylene. diphenylol propane, glycerol monoallyl ether, castor oil; 2) diamines -4,4"-methylene-bis-(o-chloroaniline), phenylene-diamines, etc. The nature of these agents determines the molecular weight of linear polymers, the density of the vulcanization network and the structure of cross-sectional chemical bonds, the possibility of the formation of domain structures (see below) and, as a consequence, the complex of St. P. and their purpose (foams, fibers, elastomers, etc.).

4. Catalysts: 1) urethane formation - tertiary amines, chelate compounds. Fe, Cu, Be, V, Pb and Sn naphthenates, octanoate (octoate) and Sn laurate; 2) cyclotrimerization -inorg. grounds; complexes of tertiary amines with epoxides.

5. Others: ingredients used to increase the stability of ester polymers to alkaline hydrolysis (carbodiimides), emulsifiers, stabilizers of isocyanate groups during storage of polyurethane prepolymers—carboxylic acid halides.

In industry, P. synthesis is carried out in one or two stages, most often in mass, less often in solution.

The first stage of the process is drying the hydroxyl-containing component in a vacuum (80-110 °C, residual pressure 0.7-1.3 kPa) in devices equipped with a jacket and a high-speed mixer, as well as in rotary film devices, special. film dryers with nozzles through which nitrogen heated to 150°C is supplied.

In the one-stage method, in addition to hydroxyl-containing compounds. and diisocyanates, elongation and structuring agents are simultaneously introduced into the apparatus; the process is carried out at 20-100 °C until the isocyanate groups are exhausted, the number of which at the beginning of the process is practically in an equimolar ratio with the sum of hydroxyl and other functions. groups of components containing an active hydrogen atom (water, alcohols, glycols, carboxyl-containing compounds). In this case, a series of series-parallel flows occur. Therefore, this method is mainly obtained. highly cross-linked foam plastics, paint and varnish coatings, as well as relatively low molecular weight ones, especially linear, fiber-forming plastics and plastics.

To more clearly separate the processes of chain elongation and cross-linking, a two-stage method is used, in which at the first stage the so-called. isocyanate pre-pol and mer containing terminal isocyanate groups (mol. wt. 1000-5000; molar excess of isocyanate groups to hydroxyl groups - not less than 2). The process is usually carried out periodically. method in apparatus with a stirrer at 80-110 ° C in the presence. catalyst in an inert gas atmosphere. The control of the region is carried out based on the decrease in isocyanate groups, the number of which should decrease by no more than 2 times compared to the initial one.

At the second stage, interaction is carried out. prepolymer with elongation agents (in the synthesis of linear polymers) or elongation and structuring at 20-100°C. In this case, an equimolar ratio is most often used between the isocyanate groups of the prepolymer and the sum of the active H atoms of the elongation and structuring agents. At this final stage of synthesis, when producing linear polymers, the polymer melt is squeezed out of the apparatus and, after cooling, the blocks are granulated (thermoplastic elastomers and plastics are obtained) or subjected to rolling (rubbers). When carrying out the process in a solution, polymer solutions are poured into containers for the afterbirth. processing (adhesives, solutions for forming fibers).

According to another method, when synthesizing reticulated P. in bulk, using both one- and two-stage technol. scheme, a liquid reaction is obtained. mass by intensive mixing of components in injection molding machines, decomp. type equipped with dosing devices. The mixing chambers of the machines are highly efficient mixing devices with a speed of up to 30 thousand per minute; reaction residence time mass in the chamber does not exceed 5-10 s. The resulting mass is poured into molds of the required configuration, where “reaction molding” is completed, i.e., the production of products (foam plastics, elastomers).

Properties. Linear polymers are solid amorphous or crystallizing polymers; they say m. (10-50) 10 3; almost completely dissolved. in highly polar (DMF, DMSO, propylene carbonate) or proton-acceptor (dioxane, THF) solutions. Reticular P. swell to a limited extent in these media; their properties are determined not only by the structure of the original components, but also by the density of spaces. mesh (degree of stitching). Functional urethane oligomers are viscous liquids (viscosity from hundreds to several thousand poises); they say m. 1000-5000; sol. in many org. r-retailers.

P.'s properties are determined by the presence of specific interactions. character (hydrogen bonds, bonds of the ionic type) and nonspecific (dipole-dipole, van der Waals interactions, as well as crystallization), the total contribution of which to the formation of the St. P. complex is decisive.

When hydrogen bonds are formed, the proton donors are the H atoms of urethane groups; in the case of polyurethane-ureas and polyamidourethanes, the H atoms of the corresponding functional groups. groups; proton acceptors are the following carbonyls. groups, as well as ester groups in the case of polyetherurethanes and ether bonds in the case of polyoxyalkylene glycols. Urethane, urea, and other groups present in the structure of P. also participate in dipole-dipole interactions. As a result of the manifestation of specific forces. intermol. interactions in P.'s structure, associates arise, the so-called. domain formations that are thermodynamically incompatible with the mass of the main polymer chains, but are chemically associated with them. As a result of this incompatibility, microphase separation (microsegregation) occurs at the supramolecular level. In this case, the phase formed by associates is a kind of reinforcing “active filler” in P. In particular, this explains the possibility of obtaining materials with high structural properties based on P. properties (strength, hardness, tear resistance), without the introduction of active fillers.

In the so-called segmented P. (block polyurethanes), synthesized from isocyanate prepolymers, upon production of which the ratio of isocyanate and hydroxyl groups was more than 2, and an equimolar amount of low molecular weight. diol (chain elongation agent), domain structures are formed due to the high concentration of blocks of neighboring urethane groups in ionomers, the so-called. cationic compounds, domain structures, are formed in the form of quaternary ammonium compounds.

All intermol. interaction also play the role of "physical." cross links. Strengthening effects due to the presence of domain structures appear only in combination: 1) with nonspecific interactions. character, eg. with the appearance of crystallinity (the use of crystallizing aliphatic diisocyanates and diols to obtain fiber-forming polymers and certain thermoplastic elastomers); 2) with strong cohesive interaction. aromatic diols (use of aromatic polyesters and diols to produce thermoplastic elastomers); 3) with the presence of chemicals. cross-links (molded polystyrene foams, elastomers, adhesives and paint coatings).

Strong intermol. interaction determine the specificity of spaces. mesh P.: being formed only "physical." cross-linked (thermoplastic elastomers, plastics, fibers), it provides the properties of quasi-mesh materials (high strength at room temperature, hardness, etc.). To obtain high strength indicators for unfilled P., capable of functioning at elevated temperatures. t-rah, mixed spaces are needed. mesh from "physical." and chem. cross-links, and the number of the latter should be small. Otherwise, chem. communications will be impeded. conformation of P. chains and, accordingly, the implementation of intermolecular forces. interactions.

Availability of intermol. interactions also determines the characteristics of relaxation. behavior P. On the one hand, these are creatures. reduction of fur. indicators under repeated exposure to loads due to partial destruction of the “physical.” connections, including under the influence of developing t-r, on the other hand, the equilibrium nature of the labile “physical.” connections, their ability, as a result, to be redistributed and restored after removing the load and a period of “rest”; This explains the regeneration of St. P., which is especially evident in the case of foam plastics.

The advantages of polymers that determined the rapid development of their production (especially in foamed form): 1) polymers of this class have a unique complex of properties: high strength and hardness in an unfilled state, combined with elasticity, oil and gasoline resistance, good adhesion to a wide range of materials, radiation. durability and, finally, exceptionally high abrasion resistance, the size of which surpasses most known polymers.

2) Varying the nature of the initial components and simply changing their ratio makes it relatively easy to obtain a wide range of materials - plastics, elastomers, fibers, foams. In the same ways, you can vary the methods of processing P.: the so-called. reaction molding, or reaction-injection. molding (produce injection molded plastics, foams and elastomers); injection molding (thermoplastic elastomers, fibers); on standard rubber equipment. industry (so-called rollable urethane elastomers).

3) Technically valuable foamed foams are obtained, as a rule, not by introducing blowing agents or using gases, but as a result of interaction. isocyanate components with water, carboxyl-containing polyesters or others; in this case, favorable conditions are created for the formation of the macrostructure of the foam material simultaneously with the chemical. districts of his education.

Disadvantages of P.: low resistance at increased. t-rah and to the action of alkalis, the accumulation of residual deformations under the influence of prolonged loads, sharp dependence physical-mechanical. St. from changes in temperature.

Application. Linear P. is used as plastic. masses, polyurethane fibers, thermoplastic elastomers, for the production of arts. leathers, adhesives (see Synthetic adhesives), rolled plastics. Mesh plastics are used as polyurethane foams, urethane elastomers, varnish coatings (see Polyurethane varnishes), and sealants. Polyurethane ionomers are used to produce latexes used in the paint and varnish industry, for the preparation of adhesives, the production of electrically conductive materials, and in medicine.

Urethane EPS is the basis of reinforced rubbers, impact-resistant plastics, specials. adhesives, varnishes, vibration- and noise-protective materials. Urethane function. oligomers-casting curable compounds; They are also used for preparing adhesives and producing paint and varnish coatings. "Isocyanate-free" P. are used in the manufacture of industrial floors. buildings and structures.

The largest consumers of P.: automotive industry (up to 25% of total production), furniture manufacturing (up to 20%), construction (16%), in the production of refrigerators (9%), the rest. agriculture, electronics, shoe industry, production of cultural and household goods.

World production of P. approx. 3.5 million tons (1986); Of these, foam plastics account for up to 87%.

The largest producers of P.: USA, Canada (up to 37% of total output), Western. Europe (up to 42%), Japan (12%), other countries (10%).

P. was first obtained in Germany in 1937 by O. Bayer and his colleagues.

Lit.: Lipatov Yu. S., Kercha Yu. Yu., Sergeev L. M., Structure and properties of polyurethanes, K., 1970; Wright P., Cumming L., Polyurethane elastomers, trans. from English, L., 1973; Encyclopedia of Polymers, vol. 3, M., 1977, p. 63-70; Composite materials based on polyurethanes, trans. from English, ed. J.M. Buista, M., 1982; Lyubartovich O. A., Morozov Yu. L., Tretyakov O. B., Reaction formation of polyurethanes, M., 1990; Advances in urethane science and technology, ed. by K.. C. Frisch and S. L. Reegen, v. 1 -4, Stamford, 1971-76; Frisch K.C., "Popular Plastics", 1986, v. 31, no. 3, p. 17-21; UTECH" 86: Polyurethane industry"s international conference. The Hague, March 18-20, 1986, v. 4-7, L., 1986. "

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Application for product/service

(PU for short) is a polymer characterized by elasticity and wear resistance. Polyurethane products are widely used in the industrial market due to their wide range of strength properties. These materials have replaced rubber products, as they can be used in aggressive environments, under high dynamic loads and over a wider temperature range. The operating temperature range for this material is, respectively, -60 °C - +110 °C.

On the industrial market, polyurethane is most often presented in the form of solid blanks (sheets, rods). But softer forms of polyurethane are also used, as well as material in liquid form.

Buy sheet polyurethane possible thickness from 5 to 80 mm, sheet size - 50x50 centimeters mm. Rods - with a diameter of 20 - 200 mm and a length of 400 - 600.

Polyurethane products provide serious competition to metal, plastic and rubber counterparts.

PU is a modern, popular and safe polymer. It is used for the production of a variety of consumer and industrial goods that make our lives more convenient and at the same time are environmentally friendly.

Properties, characteristics of polyurethane

Polyurethane (PU), characterized by high elasticity and viscosity, belongs to the group of elastomers. These materials are capable of elongating under load (tension) and returning to their original state without structural changes after the load is removed.

If we consider the “polyurethane - rubber” pair, then the first material is superior to the second in:

elasticity - the relative elongation at break of polyurethane is twice as large;
strength - strength is twice as high;
abrasion resistance - the wear resistance of polyurethane is three times greater;
resistance to ozone - does not collapse when interacting with ozone.

Polyurethane sheets, rods, and other products are distinguished by physical and chemical properties that determine the possibility of their use in various fields of industry:

polyurethane is neutral to a number of acids and solvents, so it is used: in printing houses (printing device rolls), chemical industry, for storing chemical reagents;
high hardness (about 98 units on the Shore scale) allows it to be used instead of metal where there are high mechanical loads. For example: for the manufacture of leading structural elements of tracked vehicles;
The elastomer has high impact strength and vibration resistance. These qualities make it possible to use it for the production of drive belts, conveyor belts, springs, sieves for screens in the mining industry, dampers, and other products;
resistance to high pressure makes it possible to use for the production of cuffs, rings, bushings, liners, and high-strength oil seals;
PU has low thermal conductivity. It retains elasticity at temperatures as low as -50 °C. Also works at temperatures up to 110°C and can even withstand short-term temperature increases up to 140°C. This makes it possible to use the polymer for insulating refrigerated warehouses, manufacturing polyurethane wheels or wheels rubberized with polyurethane;
Due to their resistance to gasoline and oils, the above-mentioned rubberized wheels are more preferable in terms of service life than rubber and rubber ones. Also, in terms of service life, polyurethane seals used in the oil industry win;
polyurethanes are dielectrics, therefore the polyurethane coating provides not only water, thermal, but also electrical insulation;
chemical inactivity, resistance to mold and microorganisms makes it preferable for use in the food industry and medicine;
polyurethane sheets, bushings, rods, and other products can be subjected to repeated deformation without changing their strength properties. Long service life and reliability make such products more in demand compared to rubber analogues. For various industries it is possible to produce wheels, rollers, rollers, shafts coated with polyurethane, as well as rubberized mill drums or direct grinding surfaces.

Summarize. Polyurethane parts are little susceptible to the aging process and are resistant to environmental influences, moisture, chemical elements, abrasive wear, and corrosion. In terms of their properties, they are not inferior to metal, plastic and superior to rubber products.

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

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

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

Most common injection molding polyurethane SKU-PLF, SKU-7L.

Let's consider the physical and chemical characteristics of cast polyurethane SKU-7L:

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

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

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

Polyurethane rods

This is a cylindrical blank made of wear-resistant elastic polymer. The quality of polyurethane rods is comparable to TU 2226-001-37455706-2011.

The methods for producing PU rods are similar to the methods for producing PU sheets: casting, extrusion, pressing.

There are two main overall dimensions of the rods: diameter from 20 to 300 millimeters, length, which is determined according to TU 84-404-78 by the indirect method. The main condition is that a workpiece of a certain diameter should not weigh more than 150 kilograms.

Unique properties polyurethane rods, due to the ability to synthesize polymers with different properties (for example, with different friction coefficients), make them widely in demand in many industrial fields. For example, the following products are produced from polyurethane rods:

construction industry - facade elements, fasteners resistant to vibration loads;
production of machines, mechanisms - parts in contact with oils, shafts, bushings, bearings;
medicine - implants, prostheses;
light industry, as an example - shoe, textile.

Foamed PU (foam rubber)

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

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

Advantages, disadvantages

It is used in industry along with other materials such as metal, rubber, plastic. One of the main advantages of PU is the ability to obtain a product with the required adjustable friction coefficient. Also worth noting is strength, hardness, comparative lightness, and the ability to elongate up to 650%. In addition, PU is a dielectric that is resistant to weathering and chemicals.

Polyurethane or metal?

Let's compare the “metal - polyurethane” pair to determine the positive properties of the latter. PU parts are more elastic, less heavy, and resistant to abrasives. Does not conduct electricity, has soundproofing properties. Polyurethane parts are more durable and cheaper than similar ones made of metal. The use of PU in production requires less investment during operation and repair, which leads to a reduction in the cost of the final product.

Polyurethane or rubber?

The rubber-polyurethane pair reveals the following advantages of PU: resistance to high loads, dirt, and oils; the ability to quickly restore shape after deformation; high elasticity.

PU or plastic?

And when considering the “plastic - polyurethane” pair, we can note the following advantages of PU: resistance to mechanical and impact influences, preservation of elasticity (even at low temperatures); resistance to abrasive compounds. Also, if necessary, a thicker layer can be formed from polyurethane than from plastic.

The main disadvantage of polyurethane sheets, rods, and other products is the difficulty of processing and waste disposal.

The material is unstable to chemical reagents such as nitric, phosphoric, and methanoic acids. In addition, at high temperatures, PU can be destroyed by prolonged interaction with alkalis. Polyurethane parts can change their physical and chemical properties when operating in a temperature range different from the operating one.

A number of products made from PU have significant disadvantages. For example, shoes with soles made of polyurethane material are considered “poorly breathable.” And stucco molding and cornices made of polyurethane foam can be easily damaged during operation due to their porous structure.

Manufacturing of polyurethane

PU is made using 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, foam (foam, foam rubber);
solid (sheet, rod, plate);
sprayable (polyurea).

To produce solid PU, the technology most often used is injection molding or pouring a liquid molten mixture into open dies without pressure. Less commonly, the technological process of extrusion (extrusion) is used to obtain solid PU.

Price, dimensions, weight

The final cost of polyurethane sheets is determined by their thickness, size, brand, manufacturer, total order volume, and other factors (for example, delivery). The wholesale price is always lower than the retail price. Wholesale cost of 10 mm polyurethane sheet (0.5×0.5m) - from 1878 rub. (imported production) to 2160 (domestic). Plates with a thickness of 40 and 50 mm are more expensive - 8600 and 10760 rubles per sheet, respectively, standard dimensions, 0.5 × 0.5 m. For a polyurethane sheet 80 mm thick in standard sizes you will have to pay 14800 rubles, the weight of the plate will be about 24.5 kg ).

Weight of polyurethane sheet size 0.5*0.5 meters (thickness, mm – weight, kg):

5 - 1,65;
10 - 3,12;
15 - 4,74;
20 - 5,9;
25 - 7,95;
30 - 9,2;
40 - 12,5;
50 - 15,5;
60 - 19,6;
80 - 24,5.

The wholesale price of polyurethane rods starts from 94 rubles/piece (length 0.5 m, diameter 20 mm, weight - 240 g, imported). The cost of 1 kg of polyurethane rods (domestic) is from 690 rubles. A polyurethane rod with a diameter of 35 mm will cost 335 rubles. per piece, 50 mm - 665 rubles, 60 - 975, 80 mm - 1400 rubles, 100 - 2700, 150 mm - 6090, 200 mm - from 10810 rubles.

The price of polyurethane foam starts from 400 rubles per kilogram.

Story

Experiments to obtain a universal product capable of competing with plastic, rubber, and metal were conducted independently in the USA and Germany in the period from the 30s to the 40s of the last century. American chemist W. H. Carothers invented artificial rubber and nylon, and the famous German chemist-technologist O. G. Bayer is considered the inventor of polyurethane. O. G. Bayer and his team were the first to synthesize elastic, hard polyurethane elastomers.

Industrial production of the material began in Germany in 1944, in America more than ten years later - 1957.

In the USSR, work on the problem of polyurethane synthesis began only in the 60s.

During our work, both domestic and imported products have undergone many changes aimed at improving quality and developing materials with unique characteristics.

Application

Polyurethane sheets, rods, bushings, and other products, due to their versatility, are used in various industries. Here are some of them:

construction (thermo- and water-insulating panels, sheets, stucco molding, cornices);
chemical industry (adhesives, sealants, varnishes, paints);
paper, printing industry (rollers, rollers, surface coatings);
production of machines and mechanisms (machine components and parts, seals, surface coatings);
oil and gas (seals, oil-resistant valves);
mining industry (screens, coatings and grinding parts of mills);
radio electronics (insulating materials);
light industry (thread spools, twisting rollers, adhesives, substrates);
medicine (catheters, implants, prostheses);
food industry (conveyor belts).

So, polyurethane rods, sheets, and other products are in many ways superior to rubber, ordinary plastics, rubbers, and even metal in their technical characteristics, due to which the consumption of these products increases significantly every year. New application possibilities open up.

Polyurethane is one of the most popular multifunctional polymers and construction materials.

Polyurethane is called the material of the future. Its properties are so diverse that they practically have no boundaries. It works equally well in our usual environment and in borderline and extreme conditions.

Properties of polyurethane

It is based on two types of raw materials - polyol and isocyanate. This synthetic polymer material belongs to the group of polyester polyols and its properties and technical characteristics depend on the molecular structure. Polyurethane is also an elastomer, a material that, when stretched, returns to its original state.

Numerous additives give it special properties, which, when reacting, increase elasticity, impart softness or hardness, and resistance to temperature changes.

So polyurethane has several different states, it is produced in the form of a viscous liquid, soft rubber, hard plastic, and can have a high or low degree of elasticity.

Regardless of the form in which the material is presented, it does not subsequently change due to the influence of thermal or mechanical influences; if necessary, the product can, for example, stretch, but then always returns to its original shape. Polyurethane is also resistant to contact with chemical liquids, oils, ultraviolet rays, bacteria and fungi. It is successfully used in the Far North and hot countries, in the creation of hydraulic devices and in the space industry, in construction and engineering.

Specifications

The technical characteristics of polyurethane make it an indispensable structural material in many industries, where products must have high resistance, wear resistance, and resistance to aggressive environmental influences.

The density of the polymer depends on its type; indicators can be in the range of 30-300 kg/m3.
Hardness on the Shore scale (A, D) is in the range of 50-98 units, which allows it to be used under high mechanical loads.
It has a wide operating temperature range, from -60 to +80 °C, short-term use at +120-140 °C is possible without loss of technical characteristics.
The polymer has high elasticity with high material hardness, its strength indicators reach up to 50 MPa. It can stretch up to 650% without damage.
Does not conduct electricity.
It has a low weight, which provides an alternative to using products with less weight.
Ozone resistance is also a definite plus; it is not destroyed by ozone, like rubber, for example.
High resistance to acids, oils, solvents.
When producing a polymer, you can program the required friction coefficient and obtain a material with a very low or high coefficient.

The main competitors of polyurethane are rubber, plastic and metal. But they are all inferior to him in many technical characteristics.

Compared to rubber, it has higher wear resistance and elasticity, is not susceptible to oils, gets dirty less, ages slower, takes shape faster after deformation and withstands mechanical stress better.

If we compare polyurethane with metal, it is obviously more elastic, lighter in weight, does not conduct electricity and is less susceptible to abrasives. Polyurethane is also much cheaper to produce and maintain; mechanisms equipped with parts made of this material create less noise. All this affects the quality and cost of the final product.

Compared to plastic, polyurethane shows better results at high and low temperatures; it is more elastic and does not crack under impact or other mechanical stress.

The disadvantages include:

Air tightness, which is important when creating shoes and clothing;
Shrinkage of foamed decorative parts and difficulty in applying a clear pattern;
Excessive hardness and brittleness during prolonged cold exposure;
Low resistance to torsion.

Therefore, it is extremely important to choose the right type of polymer for use in certain conditions. The absolute disadvantage of the material is the difficulty of recycling products made from it.

Areas of use

Polymer material has a very wide and varied scope of application. It is used in various forms, as a rule, it is: sheet material, liquid or in the form of polyurethane foam.

Sheet metal is used to produce lining elements, press parts, coatings for rollers, wheels, shafts, seal rings, cuffs, plugs, etc. Porous seals, fillers, and foam rubber are made from polyurethane foam. Liquid or in spray form is used to coat concrete structures, cars, car bodies and cabins, hatches, and roofs. It is also included in sealants, adhesives, varnishes, paints, heat and waterproofing products, and is also used in the production of moldings - molds for casting products.

Today, the functioning of many industries is no longer possible without the participation of polyurethane; its use has contributed to the development of new technologies and the reduction of production costs.

In heavy industry, this material is needed for the production of shock-absorbing elements.

In construction, polyurethane is indispensable in creating anti-slip coatings, vibration-resistant surfaces, and durable facade structures. In mining and quarrying it replaces rubber and even steel.

The polymer is widely used in the automotive industry. It is used to produce tires, unstable mechanical elements, silent blocks, shafts, bearings and much more.

In the furniture industry, it is needed in the production of mattresses, fasteners, gaskets and seals, cast chairs and armchairs, garden furniture, and decorative elements.

Polyurethane is in demand in the textile and footwear industries; it is used to make soles, waterproof and protective covers, zippers and rivets, carpets and insoles. They even make clothes from it, for example, polyurethane 100 is an excellent imitation of natural leather, just as soft, environmentally friendly, lightweight, only more durable.

In medicine, condoms, prostheses, implants, elements and coverings for crutches, beds, and strollers are made from it. Rare medical equipment can do without parts made from this material.

Polyurethane is also widely used in the production of sports equipment, running track coverings and stadium coverings.

Production

Polyurethane is a derivative of polyol and isocyanate, products of the petrochemical industry. To achieve certain technical properties, various additives are added to them, that is, when producing polyurethane as a raw material, it is necessary to take into account its further scope. Today it is the most sought after polymer in the world across all major industry segments. Both foreign and domestic materials are represented on the synthetic polymer market.

In the production of products, technological methods such as casting, extrusion, pressing, and pouring are used.

Casting products

The most common method of producing polyurethane products is casting. It is used to manufacture products such as bushings, cuffs, rings, bearings, self-lubricating parts, suspension parts, sealing elements for hydraulic and pneumatic mechanisms. A big advantage of producing polymer products by pouring is the low cost of molds, which makes the finished product attractive in price.

Three technologies are used to create products from this polymer by casting: rotational casting, free-form casting and injection molding.

Rotational casting is used to cover large areas and cylindrical parts with polyurethane. The polymer is applied with special equipment onto a rotating shaft, and the entire procedure is controlled by a computer. Rotational casting is carried out without heating, is a low-waste production and allows you to completely adapt to the client’s tasks.

Free casting is used to create complex shapes, in some cases the finished product can weigh half a ton. Thanks to computer control, casting into a mold takes place under precise control of the dosage of the polymer, its temperature and the pressure under which it enters. This allows us to produce high quality products.

Silicone molds are used for free casting, and this method is used to create products in limited editions. The advantage of casting is the short time required and the low cost of the finished product.

Injection molding allows for faster production and is necessary for large batches. This method is suitable not only for polyurethane, but also for other polymers.

Features and interesting facts

Polyurethane was first produced in the 40s in Europe. In the course of long laboratory research, the famous chemist, scientist and technologist Bayer Otto Georg Wilhelm obtained a previously unknown material with stunning technical properties.

In the same year, the first plant was created and the new polymer was released onto the market. But it found widespread use only 20 years later, when it began to be widely used in various industries. The American companies Union Carbide and Mobay Chemical Corporation were the first to produce polyurethane and products made from it.

People who are interested in modern construction or manufacturing often come across a material such as polyurethane. What it is and how it is used, you can find out in detail in this article. This substance is a very elastic polymer that is widely used in various areas of our lives: construction, medicine, heavy, shoe or clothing industries. Naturally, this substance is synthetic. It has a lot of advantages, which you will now learn about.

Advantages of the material

The presented material has quite a lot of advantages:

· Resistance to wear, aging and external influences.

· High strength.

· It is possible to change the level of elasticity of the material.

· Possibility of using the substance under high load.

· Wide temperature range in which polyurethane (you already know what it is) can be used.

· Used in many areas of human life.

· It is used to produce sealants, clothing, insulation, shoes, pipes and other products that are used in everyday life.

· Durability.

· Affordable price. This material, no matter what characteristics it has, is inexpensive, so it can be purchased by anyone with average or even

· Practicality and versatility.

· No deformation.

· Does not leave marks on the surface with which it is interacted.

Properties and technical characteristics of the material

The most common material today is polyurethane. What it is, what advantages it has, you already know. Now let's look at the technical characteristics of this substance.

So, the presented material can safely work in an aggressive environment, while its quality properties practically do not change. In addition, the substance works well in a fairly wide temperature range: from -60 to +80 degrees. Sometimes it can be heated to 120 o, but this process should not last long, otherwise the material will simply collapse.

The polymer is able to withstand heavy loads and is less susceptible to aging than other substances. It is resistant to wear, moisture, temperature changes, sunlight, salt, and organic solvents. Polyurethane (you already know what it is) is considered a very durable material. Moreover, its elasticity can be programmed during the production process. This material may have different characteristics, which determine the scope of its application. It should be noted that polyurethane can consist of one or more components.

Features of the production of the presented material

It should be noted that the production of polyurethane cannot be called simple. It takes a lot of effort, labor and energy. The process itself occurs by mixing several elements: polyol and isocyanate. In addition, polyetheramines are also added to this mixture. The entire process is carried out on fairly expensive equipment.

It should be noted that the raw materials are produced in a few countries: Russia, Germany, the USA and Italy. The presented material is manufactured and processed in several ways: casting, pressing, extrusion.

What products are made from the presented material?

Polyurethane is a very common material. A lot of products are made from it. For example, in medicine it is used to produce condoms, which are durable, smooth, low cost and environmentally safe. Tires for car wheels are also made from this substance. They not only last much longer than rubber ones, but also do not leave marks.

It is also worth mentioning such polyurethane products as o-rings, bushings, and cuffs. This substance is used as insulation. The presented material is also used in the furniture industry for the manufacture of mattresses. If you buy polyurethane rollers, you can be sure that they will last for a long time.

A variety of suction cups, guide elements, bandages, linings, pulleys, pipe slats and other items are also produced from this material.

Where is polyurethane used in liquid form?

It must be said that this material can be used in different forms: liquid, foam and solid. The first type of substance is most often used for waterproofing flat roofs. The advantage of this material is its resistance to wear, moisture and other external influences. In addition, liquid polyurethane can be used on difficult areas of the roof where another insulator would be difficult to use.

It should be noted that the presented material can be used to seal holes and cracks in an old roof. The advantages of such waterproofing are:

Good adhesion;

Quick drying;

Strength;

Availability;

Ease of use;

Resistance to the negative influence of the external environment;

Ecological cleanliness.

Decorative products made from the presented material: advantages and features of use

It must be said that the presented material is used for the production of interior decoration elements. For example, decorative polyurethane is used for the production of cornices, ceiling plinths or other products. Stucco molding made from the presented substance is very popular. It is distinguished by its strength, resistance to mechanical loads, and the ability to create non-standard shapes. It should be noted that you can make decorative elements to order.

The advantages of such products are:

Strength;

Decorative appeal;

Easy installation;

Easy to maintain and use;

Low cost;

Different shades.

It must be said that, unlike gypsum decorative elements, polyurethane products do not turn yellow over time. In addition to cornices, you can order the production of columns, pilasters, and beams for stairs.

Features and use of polyurethane foam

The most popular material in construction and renovation is polyurethane foam. It has light weight, good heat and sound insulation qualities, and low cost. It is resistant to steam, moisture, sunlight and temperature changes.

Using this substance is quite simple. You just need to apply it to the desired area. However, it must also be taken into account that the material can increase in size. The advantage of the substance is good adhesion and the possibility of coloring.

In principle, these are all the features of using the presented material. Good luck!