Implications of Changing Hazard Classifications for Tin Catalysts
SpecialChem / Aug 29, 2007
As Lewis acids, organotin (IV) compounds have been a popular choice to perform the catalysis common to a number of adhesive polymerisation systems. Silicone and epoxy systems alike rely on the right pH to elicit their respective hydrolytic and ring-opening polymerisations at an appropriate speed. In many cases organotins behave as particularly effective catalysts, giving unparallelled tack-free and cure-through times in well tailored adhesive formulations, as well as being used in foams and coatings. The toxicity of tin compounds has been known for many years, particularly in the marine environment. In Japan, their use has already been severely restricted, and banned in many cases. At the beginning of the year, the European Chemicals Bureau changed the hazard classification of the commonly used catalyst dibutyltin dilaurate (DBTL) from harmful to toxic2. The bureau linked to toxicity of DBTL to that of dibutyltin dichloride (DBTC), which studies have shown to be toxic to reproduction and also when repeatedly ingested.
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