摘要 |
<p>Isocyanate condensates containing free NCO groups are separated and purified from crude reaction mixtures thereof which include unreacted excess di- or polyisocyanate monomer and at least one isocyanate antagonist, by extracting such crude reaction mixtures with an inert gas, notably carbon dioxide, in either the liquid or supercritical state; the highly purified isocyanate condensates are well adopted for the production of foams, elastomers, adhesives, paints and varnishes.</p> |