Production of Isocyanates for Polyurethane Production

Control of polymerization in the production of isocyanates and polyurethanes

Polyurethanes (PUs) are used in the manufacture of many different items, such as paints, liquid coatings, elastomers, insulators, elastics, foams and integral skins.

Polyurethanes are produced by polymerization of a diisocyanate with a polyol.

The most commonly used isocyanates for the production of PU are methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI). If color and transparency are important, an aliphatic diisocyanate such as hexamethylene diisocyanate (HDI) is used. 

Vaisala Polaris™ process refractometer provides accurate and reliable refractive index measurement for different applications in the production of isocyanates and PU.

For example, the in-line refractometer is monitoring continuously the progress of the polymerization reaction. This helps to determine the degree and end-point of the reaction.

Another critical task performed by the refractometer is the measurement of concentration of isocyanate MDI, TDI, HDI after the reaction and the purification steps. This ensures the right concentration is always fed to the polyurethane process. 

The in-line refractometer can also monitor and control the concentration of  feed catalyst or recovered solvent.

Learn about the details of measurement in isocyanates and PU production from the application note.

Download the application note in PDF by filling the form.

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