Three different groups of compounds are classified with the generic name of isocyanates:
Pure isocyanates, compounds containing only isocyanate MDI without reacted NCO groups. Highly reactive, these compounds show low stability and poor formability.
Quasi-pre-polymers, compounds partially reacted with polyols, polyol equivalents in the pre-polymer are <1/2 those of pure isocyanate. They are stable compounds over time, and they show a more balanced utilisation ratio with formulated polyols.
Prepolymers, compounds with a base of pure isocyanates, where polyols equivalents are >1/2 equivalents of isocyanate. These compounds are very stable, show high viscosity, and best mechanical characteristics.
Our company supplies quasi- prepolymers MDI based that allow a better formability with respect to pure isocyanate; they are stable over time and provide a higher control of polymerisation, thus maximizing mechanical characteristics.