The use of alternative blowing agents for the production of polyisocyanurate (PIR) rigid foam has created a need to better understand how various catalysts participate in isocyanurate formation. The improvement of isocyanate conversion to isocyanurate is one approach to overcome the greater flammability inherent with the use of hydrocarbons. In situ Fourier Transform Infrared (FTIR) has been used to follow the reaction kinetics of PIR development during foam preparation. The activity of amine catalysts for isocyanate conversion is characterized through the use of in situ FTIR. Identification of the reaction products formed from the blowing, gelling, and trimerization reactions provides the opportunity to profile the catalytic effects as the reaction proceeds. Several traditional amine catalysts used by PIR foam manufacturers have been evaluated. The design of catalyst blends in PIR formulation can now be based upon the results of the catalytic activity characterization. In this article, the focus is on understanding the synergies between catalysts used in PIR formulations. Real-time in situ FTIR is the technique of choice for the evaluation of catalysts blends for optimal performance and processing properties.

The use of in situ Fourier Transform Infrared (FTIR) to follow PU reaction kinetics has been studied using a heated probe matching the PU material temperature. The results obtained show that, although not giving access to concentration of formed chemical bonds, the technique is a unique tool to assess subtle differences in catalysts behavior during actual PU formation, going beyond the currently used but restrictive characterization of catalysts in terms of gelling, blowing or trimerization grades. Examples of the use of the technique for the development of new amine catalysts are given for flexible and rigid foams. For flexible foams, it is shown that FTIR characterizes the gel potency in good agreement with the behavior of known gel catalyst molecules and is therefore a good tool to develop new ones. Results comparing gel strength and foam emission data show that several experimental grades have potential to be brought on the JEFFCAT® Catalyst range. They also confirmed the good performance of commercial low emission grades such as JEFFCAT® ZF-10 as blow catalyst and JEFFCAT® ZR-50, DPA and Z-130 as gel catalysts. For rigid foams, it is shown that FTIR provides good insight into the extent of trimer formation and is therefore the technique of choice to optimize catalyst blends for best fire performance and processing.