Patent ID: 8748655
Filing Date: 2014-06-10
Classification: C07C

Abstract:
1. A process for preparing a polyphenylene-polymethylene polyisocyanate, the process comprising: (a) reacting carbon monoxide with chlorine to form phosgene; (b) reacting phosgene from (a), in an excess, with at least one primary amine excluding mono- and polyphenylene-polymethylenepolyamines, to form at least one first reaction solution comprising an isocyanate, and hydrogen chloride; (c) separating excess phosgene from the first reaction solution; and (d) reacting at least a portion of the phosgene separated in (c) with at least one polyphenylene-polymethylenepolyamine to form a second reaction solution comprising a polyphenylene-polymethylene polyisocyanate.