| 摘要 |
1,181,545. Purifying polyisocyanates. TAKEDA YAKUHIM KOGYO K.K. 5 May, 1967 [5 May, 1966], No. 20980/67. Heading C2C. Crude polyisocyanates (I) which have been prepared by phosgenating the corresponding polyamines are purified by heating with an inert gas in a fractionation column under such conditions that the pressure at the top of the column is 5-200 mm Hg, and the feed rate of the inert gas is given by (R)(P)(P B -P x /P x )(#) mol./hr., wherein P x E # /P B = 0À05-0À50, E # = 0À3-1À0 and # = 0À2-20, R = (x p -y f )/(x p -x f ) ¸ [1-(x p -y f )/(x p -x f )], and P = (Fx j -Wx w )/ xp mol./hr., where PB is the operating pressure at the bottom of the column, P x is the equilibrium vapour pressure of the residue at the bottom of the column at the operating temperature, x p is the molar concentration of light components (II) in the reflux liquid (mol fraction), x f is the molar concentration of II in I (mol fraction), y f is the molar concentration of II in the equilibrium vapour of I in a feed tray at the operating temperature (mol fraction), F is the feed rate of I (mol./hr.), W is the bottom product rate (mol./hr.), x w is the molar concentration of II in the residue (mol fraction), # is a parameter determined by the properties of I and the construction of the fractionation apparatus and E # is the vaporization efficiency. Specified I are xylene (α,α<SP>1</SP>), hexamethylene, diphenylmethane (4,4<SP>1</SP>) and tolylene diisocyanates and toluene-2,4,6-triisocyanate. |
