Synthesis of isophorone diisocyanate (IPDI) based waterborne polyurethanes: Comparison between zirconium and tin catalysts in the polymerization process

In this work, a comparative study of the catalytic activity of tin and zirconium compounds in the polymerization of isophorone diisocyanate (IPDI) based waterborne polyurethanes is presented. Zirconium acetyl acetonate is much less toxic than the commonly used dibutyltin diacetate but it is deactivated in the presence of acid groups. Nevertheless, acid groups are commonly used in the synthesis of waterborne polyurethanes and therefore these groups have to be neutralized in advance for carrying out the synthesis using the zirconium catalyst. Moreover, FTIR and 13C NMR results have shown that in the presence of triethyl amine and tin catalyst, the secondary isocyanate group is more reactive than the primary group, while using the zirconium catalyst, the two isocyanate groups show the same reactivity.