PU - Polyurethane

Polyurethane is a urethane resin increasingly used to manufacture seals. It is obtained through reaction between polyol, diisocyanate and a chain extender. In seals, two main polyurethanes are used depending on the base polyol: polyether or polyester.

The diisocyanate type is also crucial. The most commonly used types are MDI, PPDI and TODI. The combination between polyol and diisocyanate typology results in very different products, whose physical and mechanical features – and resulting applications – vary significantly.

The thermoplastic polyurethanes (TPUs) currently on the market are elastomers with high performing mechanical characteristics, featuring excellent tensile strength, as well as very good tearing, abrasion and cutting resistance. They are usually compatible with mineral oils, greases, hydrocarbons and petroleum derivatives.

Standard TPUs normally have poor compatibility with hot water, acids, alkaline solutions and steam. For such applications, specific TPUs have been developed.