| 摘要 |
1,193,401. Liquid diphenylmethane diisocyanate. IMPERIAL CHEMICAL INDUSTRIES Ltd. 28 April, 1969 [14 May, 1968], No. 22884/68. Heading C2C. A process for the manufacture of a liquid diphenylmethane diisocyanate composition comprises heating at an elevated temperature a diphenylmethane diisocyanate which is solid or partially solid at 15‹ C., e.g. the 4,4<SP>1</SP>-isomer optionally containing up to 10% of the 2,4<SP>1</SP>- isomer, and a N,N<SP>1</SP>-disubstituted thiourea or N<SP>1</SP>,N<SP>4</SP>-disubstituted bis-thiourea in an amount of from 0À25 to 20% by weight of the diisocyanate and distilling out an isothiocyanate from the heated mixture. A solvent of boiling point lower than that of the diisocyanate may also be present. |
