Influence of Blocking Agent Structure on Dissociation Temperature of Ether Alcohol-Blocked Aromatic Diisocyanates in Polyurethane Coatings

The high reactivity and toxicity of isocyanates do not allow their storage and use in one pack systems. Blocked isocyanates are a solution to overcome these drawbacks. In this study diphenyl methane diisocyanate (as aromatic diisocyanate) have been blocked by three types of ether alcohol (diethylene glycol mono ethyl ether, diethylene glycol mono butyl ether and ethylene glycol mono ethyl ether).The synthesis of blocked diisocyanates was confirmed by Fourier transform infrared spectroscopy and titration technique. Thermal dissociation of blocked isocyanates has been studied by DSC and TGA analytical methods. It was found that the degree of deblocking temperature is much affected by the structure of the blocking agents and analytical technique.

Keywords:

Aromatic diisocyanates , Deblocking temperature , Polyurethane coatings , Blocking agent