Asma Polska specialises in the manufacture of flexible products made from polyurethane - an extremely versatile synthetic material. In the following article, you will learn a lot of basic information about our most important material. You are welcome!

What are polyurethanes - the material in chemical terms

These materials are abbreviated PUR or PU. Like many other complex plastics, it is actually a group of substances. A common feature of their molecules is the presence of urethane-ethane bonds: [-O-CO-NH-]. It is this that binds together the rest of the organic chains, which can far modify the properties of the finished product.

Typically, this polymer is obtained by the addition reaction of two raw materials: an isocyanate and a polyol. The isocyanate groups combine with hydroxyl groups to form urethane bonds. Control of the reaction is achieved, inter alia, by means of catalysts, e.g. special amines or organic tin compounds. In production practice, isocyanates with one or two aromatic rings are most commonly used. Polyols, on the other hand, is the general name for compounds containing more hydroxyl -OH chains. They can also be long-chain ethers or aliphatic esters.

Properties of polyurethane

As already noted, the properties of the resulting polyurethane depend, among other things, on the ingredients used. The use of long-chain polyols increases the softness and flexibility of the material, which is why the term PU rubber is sometimes (inaccurately) used. The degree of cross-linking is also very important, being higher for harder materials. Strongly cross-linked polymers are thermosetting, but there is also thermoplastic PU. In general, however, it is always an elastomer with significant resistance to organic chemical reagents.

During production, the plastic in question is often foamed at the same time. Additional foaming agents - gases or volatile liquids - can be used to create high porosity. A second method is the addition of water. When combined with isocyanates, it forms carbon dioxide in the reaction mixture itself, and this causes foaming. The porosity makes the material lightweight and thermally insulating.

Forms and variations of polyurethane plastics

These materials have a wide range of varieties. Polyurethane foams of various hardnesses are common - from very soft sponges to rigid, highly porous sheets. This polymer is also used to produce flexible spandex and lycra fibres. In addition, polyurethanes are used to make solid machine parts, which should have specific characteristics:

• impact energy absorption,
• vibration damping,
• ability to operate in elevated temperatures and humid environments,
• high-precision manufacturing,
• resistance to the effects of organic solvents,
• resistance to cutting and abrasion.

At Asma Polska, we offer a wide range of polyurethane products to meet individual requirements. It is worth remembering that greater flexibility is typically associated with lower mechanical resistance. Also, not every material is equally resistant to hydrolysis.

Fibres, foams, polyurethane rubbers - industrial applications

Polyurethane foams in their soft form are used to produce sponges and as fillings for furniture, car seats and mattresses. The more rigid form of porous PU is an excellent raw material for the thermal insulation of buildings and pipes. Prefabricated laggings and boards made from this material speed up thermal insulation and construction work. Polyurethane with improved fire resistance is sometimes used. As a joint filler, it prevents the spread of fire.

Variously woven PU fibres are irreplaceable in the production of clothing. Such fabrics are pleasant to the touch, warm and hard wearing. Elastane, for example, is a very popular addition to comfortable, stretchable garments. Polyurethane coatings, on the other hand, increase the waterproofness of, for example, jackets.

The more solid form of polyurethane presents many further useful properties. It is useful for the soles of shoes, such as trekking boots. A particular advantage is that PU can be machined: cutting, turning, milling, grooving and grinding. This makes it possible to obtain very accurate moulds quickly and inexpensively.

Parts made of PU are useful in factory machines. Shafts, rolls bushings and wheels made of this material resist abrasion and wear well and can operate over a wide temperature range and even in the presence of aggressive chemicals. In addition, bushings, rods and rings are highly resistant to dynamic loads and have excellent vibration damping. This is why they are used as automotive parts, especially in mechanically intensive areas. Polyurethane parts are superior to metal parts in many respects: they are lighter, operate more quietly, do not corrode and absorb vibration energy better.

The hardness and flexibility of these polymers make them a great material for anti-vibration components, bumpers i screens industrial. They are indispensable in flip flow mats for screening machines, which must demonstrate excellent flexibility. Seals made from this polymer, similar in consistency to hard rubber, are also common. They are particularly resistant to high compressive forces.

At the manufacturing stage, raw polyurethane can be poured onto numerous materials to which it exhibits adhesion: metal, fibreglass and some plastics. This is known as rubberising, which makes it possible to create PU coatings or covers. In this way, it is possible to combine the advantages of a steel mandrel and a polymer top coat, or to protect delicate electronic components with a layer of strong polymer. Asma Polska offers rubberisation and reconditioning services for wheels, shafts, pumps and other machine components.