Please have a look at the fantastic line up of speakers and abstracts that will be presented at the 2017 Convention.

Dr Ransi Devendra – Uroxsys

New understanding of the mechanism for the catalysis of urethane formation by organotin(IV) dicarboxylate

Surface coatings is an area of urethane technology and is rapidly gaining popularity due to ongoing performance improvements. Key to this is improved control of the catalysis of the urethane reaction obtained through an increased understanding of the catalysis mechanisms involved.

Organotin dicarboxylates are industrially important catalysts in the formation of urethanes by reacting an isocyanate with an alcohol. This catalyst works for both aliphatic and aromatic isocyanates, however the catalyst is more important for aliphatic isocyanates than aromatic isocyanate in industrial applications.

Investigations of catalysis mechanisms show that organotin dicarboxylate catalysis of aromatic isocyanates is different to the mechanism for aliphatic isocyanates for urethane formation in non-polar media. This is different from what is proposed in literature1. Results in this study reveal that for organotin dicarboxylate catalysis of isocyanates in non-polar media, the carboxylate ligand of the catalyst contributes to catalysis of aliphatic isocyanates whereas the ligand has no effect for catalysis of aromatic isocyanates.

These conclusions were arrived at by comparing results obtained from investigations based on both experimental and computational methods. The new knowledge was used to prevent viscosity increase of low temperature synthesised aliphatic urethane pre-polymers in storage that are used in the manufacture of 1K moisture cure surface coatings.

Ransi is the Science and Technology Manager at Uroxsys Ltd., New Zealand, where he had been involved with development work on catalysts for urethane pre-polymers for the past 10 years.

He was recognised as an inventor for his catalyst work by the Bayer-NZ Business community in 2009. Ransi’s professional career has involved research and development work in polymer-related topics for the past 35 years. He has a B.Sc. (Natural Sciences), M.Sc. (Polymer Science and Technology) and Ph.D. (Chemistry).