What is polyurethane and where is it used?

Properties and application

Thermoplastic polymers are called polymers, which, when heated, pass from a solid state to a soft, viscous, and when cooled, they again take a solid form. These elements are obtained by a polymerization reaction. This reaction takes place under high pressure and without the use of impurities. The polymerization reaction became possible only thanks to modern chemistry and specialized equipment. It is impossible to get this process in natural conditions.

The properties of thermoplastic polymers are caused by the way monomers are connected - the connection is carried out in one place, in one direction. In other words, the molecules are interconnected in a line with a linear view, and in the form of several lines woven into a web, with a branched structure.

Thermoplastic polymers melt well and dissolve in reagents and solvents. When the solvent evaporates, the material hardens and regains its former properties. This quality is used in the production of various adhesives, varnishes, paints, sealants, putties and other building solutions containing polymers.

The following are distinguished from thermoplastic polymers:

• polyolefins;
• polyamides;
• polyvinylchloride;
• fluoroplastics;
• polyurethanes;
• polycarbonates;
• polymethyl methacrylates;
• polystyrene.

Based on polymers, starting materials and processing methods, the following final products are distinguished:

1. plastics;
2. fibrils;
3. films;
4. coverings;
5. laminated plastics;
6. adhesives.

Thermoplastic polymers are widely used in construction in the manufacture of materials for insulation, organic glasses, films and coatings of various densities and thicknesses, thin fibers, and also as binding bases for adhesives, plasters and thermal insulation materials.

Bottles and vessels of various shapes, containers, pipes, parts of office equipment, computers and electronic equipment are made from polymers. They are also used in the production of flooring - linoleum, tiles, baseboards, decorative decorative films, wall panels and plastic.

Compare with similar jacket materials

For a long time, leatherette and leather substitutes were made and synthetic materials. They had an unpleasant odor and not a pretty appearance. They were subject to rapid wear and tear.

Polyurethane or artificial leather: which is better

As a result, people began to mistrust things of this type. Modern manufacturing technologies can greatly turn people's attitude to eco-leather for the better.

Varieties of polyurethane

Additional Information! The first samples of eco-leather were made in 1963 in the USA.

Eco-leather contains polyurethane. It is a finely porous polyurethane layer bonded to a cotton or polyester base. When they are combined, a pattern is obtained that strongly resembles leather in texture. Visually, it cannot be distinguished from natural material. It can differ only on the seamy side.

Polyurethane fabric or what it is can be found out by touching it to the touch. This material has good elasticity. Nice to the touch. The thickness of the polyurethane top layer affects the quality of the material. The larger the layer, the stronger the product will be. Stiffness also depends on it.

Polyurethane gloves

Eco-leather has many positive qualities:

Good air permeability. Air circulation passes through micropores

This is especially important in jackets and shoes.
Waterproof.
Heat conductivity.In comparison with natural leather, it maintains the required temperature at any time of the year.
Frost resistance

Able to withstand up to -35C. Does not fade when exposed to sunlight.
Products made from this material do not lose their appearance.
Eco-leather does not have an unpleasant odor.
Does not cause allergic reactions.
Does not contain harmful elements of PVC and plasticizers.
Animals are not harmed during production.
Affordable price in comparison with genuine leather.

Eco-leather is used to make:

• Clothing jackets, skirts.
• Gloves accessories.
• Shoes.
• Furniture upholstery.

PU fabric is easy to handle. Excellent cut and non-slip.

Important! Chlorine-containing substances must not be used for cleaning eco-leather. Eco leather look

Eco leather look

Minuses:

• Water hitting the surface leaves marks and stains.
• If the material is not made correctly, it can absorb paint from the fabric.
• In case of damage, the tissue base comes out.
• Requires water-repellent treatment for long-term durability.

Artificial leather - made from animal skins and undergoes a number of procedures with the addition of chemicals. Types of procedures:

• Soaking.
• Ashening.
• Tanning.
• Painting.

All of these processes are carried out using chemicals. They cause great harm to the environment. Products made from genuine leather are considered a sign of prestige and cost a lot of money.

Leather

The only positive quality of natural leather is its durability and strength. Caring for her takes a lot of time and effort.

By examining the difference between materials, the buyer can decide for himself what is best for him.

Polyester or polyurethane: which is better

Polyester has some advantages:

• Water resistance.
• No pills, puffs or other problems on the surface of the material.
• Resistant to dirt.
• Does not deform.
• Strong and durable.

Polyester clothing is currently considered the most popular. It has many more advantages than disadvantages.

Note! Comparing polyester and polyurethane, the difference is not particularly noticeable.

Holofiber or polyurethane foam: which is better

Holofiber is a chemical fiber made from polyesters. Produced only at the Termopol plant in Moscow. Tight-feeling filler made of synthetic fibers. Thermal exposure during manufacturing is the key to excellent performance. Used to make mattresses and pillows. They fill a mattress topper with a low cost. Holofiber mattresses are practical and correctly distribute the load of the body, regardless of weight.

Holofiber mattress

Important! The question is often asked: which is better or better? They are very similar in quality to each other. Polyurethane foam or PU foam is also used for filling mattresses

It was released much earlier than Holofiber. Became a revolutionary find in this industry

Polyurethane foam or PU foam is also used for filling mattresses. It was released much earlier than Holofiber. Became a revolutionary find in this industry.

It has an inexpensive price, different rigidity and is suitable for spring mattresses. In the non-spring version, a more rigid foam rubber is used. Suitable for heavier people.

PU foam filler is considered to be cheap and practical in the market. Thanks to this, it is very popular among the population.

What is plastic?

In accordance with the domestic state standard:

If you remove the first word "plastics" from such a complex definition, you might not even guess what it is all about. Well, let's try to figure it out a little.

"Plastics" or "plastics" were so named because these materials are capable of softening when heated, becoming plastic, and then under pressure they can be given a certain shape, which is retained upon further cooling and hardening.

The basis of any plastic is a polymer (the same "high molecular weight organic compound" from the definition above).

The word polymer comes from the Greek words poly (many) and meros (parts or links). This is a substance whose molecules consist of a large number of identical, interconnected links. These units are called monomers ("mono" - one).

This, for example, looks like a polypropylene monomer, the most commonly used type of plastic in the automotive industry:

The molecular chains of a polymer are made up of an almost infinite number of such pieces, connected into one whole.

Polypropylene molecule chains

By origin, all polymers are divided into synthetic and natural. Natural polymers form the basis of all animal and plant organisms. These include polysaccharides (cellulose, starch), proteins, nucleic acids, natural rubber and other substances.

Although modified natural polymers find industrial applications, most plastics are synthetic.

Synthetic polymers are prepared by chemical synthesis from the corresponding monomers.

The feedstocks are usually oil, natural gas or coal. As a result of a chemical reaction of polymerization (or polycondensation), many of the "small" monomers of the starting material are joined together, like beads on a string, into "huge" polymer molecules, which are then molded, cast, pressed or spun into a finished product.

So, for example, polypropylene plastic is obtained from combustible propylene gas, from which bumpers are made:

Now you have probably guessed where the names of plastics come from. The prefix "poly-" ("many") is added to the name of the monomer: ethylene → polyethylene, propylene → polypropylene, vinyl chloride → polyvinyl chloride, etc.

International plastics abbreviations are abbreviations for their chemical names. For example, polyvinyl chloride is denoted as PVC (Polyvinyl chloride), polyethylene - PE (Polyethylene), polypropylene - PP (Polypropylene).

In addition to a polymer (also called a binder), plastics can contain various fillers, plasticizers, stabilizers, dyes and other substances that provide plastic with certain properties, such as fluidity, plasticity, density, strength, durability, etc.

Production technology

What is polyamide and how is it made? The process of creating a synthetic substance is carried out in 2 ways:

• Polymerization of caprolactam, which involves conversion to a linear polymer.
• Polycondensation reaction of hexamethylenediamine and acid (adipic), after which polyamides are formed.

Polyamide fiber production

Both methods are performed either continuously or at regular intervals. The continuous process is more common and there is a tangible difference between the 2 modes. Continuous production of polyamides involves the following steps:

• Preparation. Salt and hexamethylenediamine are obtained from adipic acid. To obtain this component, the acid is combined with methanol in an apparatus that agitates and warms the mixture.
• Polymerization. The resulting solution goes into the polymerization compartment. There are 3 types of columns: L-shaped, straight and U-shaped. Caprolactam is transferred to the column with the solution. As a result of the reaction, boiling occurs.
• The polymer comes out of the column as a molten substance, then it is cooled. For this, baths are used.
• The polymer separated into belts goes to the grinder.
• The crumb obtained as a result of crushing is washed in hot water and cleaned of impurities.
• The crumb is dried in vacuum-type drying places.

Continuous polycondensation is similar to polymerization. The difference lies in the principle of processing the source material.

• The process of obtaining salt is similar, however, after receiving it, it crystallizes and goes further in the form of crumbs, and not a solution.
• The chain reaction is carried out in an autoclave reactor - an apparatus in the form of a cylinder with a stirring mechanism.
• Polycondensation takes place with the participation of pure nitrogen. The duration of the process is from 1 to 2 hours. The pressure is then reduced for an hour, and then the reaction is carried out again. The total amount of time is 8 hours.
• After the resulting polyamide is filtered, cooled and crushed. The material is also dried using hot air streams.

Important! The substance has several forms of release. Poly-e-carbamides - in the form of crumbs, poly-z-benzamides are produced in granules

Having undergone additional processing, polyamides are obtained in the form of rods (from 9 mm to 200 mm), sheets with different thicknesses, and bushings.

Polyurethane properties

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. Also, polyurethane is an elastomer, a material that, after stretching, returns to its original state.

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

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

Grades and technical characteristics of fluoroplastic

Today there are several brands of fluoroplastic, which differ in the size of the molecules and their number. Consider the most popular brands and their technical characteristics:

• Fluoroplast-2 (polyvinylene fluoride) has high strength and elasticity, withstands the action of aggressive chemicals. Most often used in pipelines and for the manufacture of containers for storing chemicals. There are modifications of the material with the addition of other substances, then the letter M is present in the marking.
• Fluoroplast-3 (polytrifluorochlorethylene) is characterized by high strength and hardness, at high temperatures it melts well, softens, changes shape, on the contrary, it is resistant to low temperatures. It is used as part of anti-corrosion coatings. There is a modified fluoroplastic-3 with the F-3M marking.
• Fluorolast-4 (polytetrafluoroethylene) has the highest density among other fluoroplastics, is resistant to high temperatures (can withstand heating up to 260 degrees), is highly hydrophobic and has low porosity. Today there are several varieties of fluoroplastic-4, for example, F-4PN, F-4O, F-4D and others. All of them have distinctive properties that determine their application in a particular area.
• Fluoroplast-40 is similar in properties to F-4, resistant to aggressive chemicals, does not transmit UV rays, and is not flammable. It is produced in two types - F-40P and F-40Sh.

The main technical characteristics of the listed fluoroplastics are presented in the table.

For many years in Russia, fluoroplastics have been produced in large quantities at chemical plants. The scope of application of polymers is extremely wide and is due to their technical characteristics.The material has a number of exceptional properties, thanks to which it is in demand in a wide variety of industries, and the demand for it has only increased in recent years, and, accordingly, the share of its production in the country's chemical industry is also increasing.

Properties, characteristics of polyurethane

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

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

• elasticity - the 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 degrade when interacting with ozone.

Polyurethane sheets, rods, and other products are distinguished by their physicochemical properties, which determine the possibility of their use in various industries:

• polyurethane is neutral to a number of acids, solvents, therefore it is used: in printing houses (rolls of printing devices), in the 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 caterpillar machines;
• the elastomer has high impact strength, vibration resistance. These qualities make it possible to use it for the production of driving belts, conveyor belts, springs, screens for screens in the mining industry, dampers, and other products;
• resistance to high pressure makes it possible to use high strength for the production of cuffs, rings, bushings, liners, oil seals;
• PU has a low thermal conductivity. It retains its elasticity at negative temperatures down to -50 ° C. Also works at temperatures up to 110 ° C and can even withstand brief temperature increases of up to 140 ° C. This makes it possible to use the polymer for the insulation of refrigerated warehouses, the manufacture of polyurethane wheels or wheels rubberized (rubberized) with polyurethane;
• Due to the resistance to the effects of gasoline and oils, the aforementioned rubberized wheels are more preferable in terms of service life than rubber and rubber ones. Polyurethane seals used in the oil industry also benefit in terms of service life;
• polyurethanes are dielectrics, therefore, the polyurethane coating provides not only water, thermal, but also electrical insulation;
• chemical inactivity, resistance to mold, microorganisms makes it preferable to use in the food industry, medicine;
• polyurethane sheets, bushings, rods, and other products are capable of undergoing multiple deformations without changing the strength properties. Long service life, reliability make such products more in demand in comparison with rubber counterparts. For various industries, it is possible to manufacture wheels, rolls, rollers, shafts with a polyurethane coating, as well as rubberized mill drums or directly grinding surfaces.

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

Application of polyurethanes

Large products are produced from injection molded polyurethane thermoplastic elastomers, for example, wear-resistant tires, structural, body and technical products, and numerous substitutes for rubber products.They also produce shock absorbing and damping elements for all industries, such as conveyor belts, drive belts, non-slip surfaces, various elastic rollers and rollers, seals, buffers and bumpers, etc. PU products, due to their properties and especially wear resistance, are successfully used in highly loaded devices and mechanisms. Of the industries, these are railway, automotive, engineering, footwear, medical, sports and others.

Fig. 3. Polyurethane wear-resistant rollers

Liquid polyurethane, which is also produced in the form of a spray, is used to insulate various structures and mechanisms, for example, cars, trucks, hatches, etc. In addition, it is used as a component in a variety of sealants, adhesives, varnishes, paints and other surface insulating and decorating agents.

Despite the widespread use of polyurethane elastomers, most of the PU plastics market is occupied by polyurethane foam. In addition to thermal insulation of pipes, PPU is used for spraying on almost any surface, for the production of sandwich panels and other light and durable building materials. Also PPU is used for thermal insulation of refrigerators, refrigerators, storages; in electrical engineering and production of car interiors, steering wheels; in aircraft building, car building, etc. Soft polyurethane foam is an unrivaled material for furniture and light industry.

What is it used for?

Scientists discovered that polyurethane can be made into thin threads, and this is how nylon first appeared, from which stockings are made. Over the years, it has been developed into spandex fibers. Thanks to today's advances, technologies make it possible to produce a wide range of polyurethane fabrics: from artificial leather (including suede or velor) and eco-leather for outerwear and upholstery to bags, jackets, skirts and outfits, various accessories, products for medicine and sports. In addition, the material is used to create more comfortable, durable and weather-resistant equipment such as workwear, sports jackets and raincoats, shoes and insoles.

Fact! Thermoplastic polyurethane elastomers can be formed into different fibers. When they are spun, they produce a flexible material called spandex. Elastic materials are needed for socks, bras, support sleeves, swimwear, sports equipment and more.

Innovative technologies against cruelty to animals and make PU leather a more sustainable option and with less use of natural resources. Polyurethane fabrics are used in many industries, depending on their chemical composition and properties obtained during the manufacturing process.

They are the main material for the following products.

1. Clothes, shoes and bags (including protective overalls for industrial production).
2. Textiles for furniture and the automotive industry (upholstery, soft fillers, mattress toppers).
3. Medical supplies (gloves, inflatable mattress tops).
4. Products for swimming and tourism (life jackets and boats, membrane jackets and shoes).
5. Baby products (reusable diapers).

L. Gore and Associates patented Gore-Tex in 1976, a water-repellent yet breathable material. Since then, it has been used in medical implants, for wire insulation, and in clothing and footwear. The Gore-Tex membrane has become a fairly well-known brand that offers ski and mountaineering clothing and footwear, jackets and overalls for outdoor enthusiasts. Such equipment effectively retains moisture in all weather conditions.

Polyurethane fabrics are lightweight, breathable and non-breathable. As a rule, they retain their properties for at least 100 cycles in a washing machine without harm to the material.The material is easy to work with and was originally developed for use in hospitals where a durable, waterproof, reusable cloth was required.

Is polyurethane harmful?

Due to its energy-saving characteristics, polyurethane is classified as a safe material.

However, when assessing its environmental friendliness, it is worth taking into account the possibility of harm to this elastomer in the liquid and solid state. As practice has shown, in dry form, this polyol does not emit harmful substances.

Hazardous vapors are only possible if the material is handled incorrectly.

However, violation of production technology may result in the release of the following toxic fumes.

• Isocyanates. These substances are part of paint and varnish, foam products. Their presence can cause asthma in the absence of special protection.
• Amine catalysts, which cause hypersensitivity, irritability, blurred vision. When inhaled continuously, these substances cause ulcers, irritation of the mucous membranes, burns to the mouth, throat and esophagus.
• Polyol. He is able to manifest his toxic effect only in direct contact with a living organism, namely when swallowing. Polyol poisoning manifests itself in the form of vomiting, intoxication and spasms.
• Fire retardant. This substance gradually accumulates in the body, after which it causes poisoning.

As a result of the above, we can conclude that polyurethane can only be harmful to health if it is used improperly. This often happens when using low-quality types of spray, as well as in the absence of special protection during operation.

Many are worried about the dangers of polyurethane, which is mounted in residential premises. The fears of users are in vain, since before going on sale, this category of goods undergoes a lot of safety tests. Problems can only arise if you buy an elastomer from a manufacturer that does not have quality certificates.