Determination of the Residual-Free Diisocyanate in Waterborne Polyurethane Films

ANBINDER, PABLO; PERUZZO, PABLO; AMALVY, JAVIER

Bahia Blanca

Simposio; SAP 2011 - IX Simposio Argentino de Polímeros; 2011

CCT-CONICET Bahía Blanca - Universidad Nacional del Sur

The residual diisocyanate content in polyurethanes has great toxicological concern for the well known carcinogenic effect of this family of compounds. In particular, the Argentine Food Code (Código Alimentario Argentino, CAA) has established a limit of composition (LC) of 1 mg/kg as free isocyanate in the case of polyurethanes or materials prepared using isocyanates in its synthesis. Thus, the presence of this component in concentrations greater than 1 ppm in the final film determines the impossibility of using them in contact with food. Despite this restriction, the corresponding test is not done by local laboratories. Due to the high reactivity of isocyanate group a derivatization method to produce a stable product is necessary for its detection and quantification. N,N-dibutylamine was used as derivatizing agent. The technique developed in this work was appropriate to quantify the residual content of free diisocyanate in polyurethane films for concentrations in the order of parts per billion (ppb). A simple  and low cost technique for the extraction and derivation of free diisocyanate remaining in polyurethane films has been developed.