| 摘要 |
<p>1331541 Isocyanate recovery E I DU PONT DE NEMOURS & CO 13 May 1971 [22 May 1970 4 Jan 1971] 14759/71 Heading C2C An organic isocyanate is recovered from a crude isocyanate composition containing a substantially non-volatile residue component by mixing the composition with a tar thinning agent, the tar thinning agent being an organic liquid which dissolves the residue component and has a boiling point at least 50‹ C. above that of the organic isocyanate, said tar-thinning agent being at least one liquid selected from aromatic hydrocarbons have less than 35% wt. saturates, esters of aromatic acids having C 1-12 alcohol radicals, aromatic ketones having the carbonyl radical linked to two aryl radicals, aromatic ethers having the ether oxygen linked to two aryl radicals, and fully aromatic sulphides or sulphones, and subjecting the resulting mixture to distillation while maintaining the presence of a stripping agent for the organic isocyanate whereby the distillate contains a major proportion of the organic isocyanate and the still heel contains the residue component and the tar thinning agent; the weight ratio of tar thinning agent employed to the residue component being in the range 0À2 : 1 to 5 : 1. The stripping agent for the isocyanate is preferably o-dichlorobenzene.</p> |
