METHOD FOR PRODUCING MIXTURES CONSISTING OF DIPHENYLMETHANE DIISOCYANATES AND POLYPHENYLENE-POLYMETHYLENE-POLYISOCYANATES CONTAINING A REDUCED AMOUNT OF CHLORINATED SECONDARY PRODUCTS AND WITH A REDUCED IODINE COLOR INDEX
First Claim
1. A process for preparing mixtures comprising diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a reduced content of chlorinated by-products and a reduced iodine color number, said process comprising reacting diphenylmethanediamines and polyphenylpolymethylenepolyamines (PMDA) with phosgene in the presence of at least one inert organic solvent in a two-stage reaction comprising first and second phosgenation stages, wherein the mass ratios of said phosgene to hydrogen chloride in a residence time apparatus of the second phosgenation stage are at the same time 10-30:
- 1 in the liquid phase and 1-10;
1 in the gas phase.
1 Assignment
0 Petitions
Accused Products
Abstract
In a process for preparing mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a reduced content of chlorinated by-products and a reduced iodine color number by two-stage reaction of the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, separation of the excess phosgene and solvent after the phosgenation is complete and thermal treatment of the reaction product, the mass ratios of phosgene to hydrogen chloride in the residence time apparatus of the second stage of the phosgenation are at the same time 10-30:1 in the liquid phase and 1-10:1 in the gas phase.
71 Citations
14 Claims
-
1. A process for preparing mixtures comprising diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a reduced content of chlorinated by-products and a reduced iodine color number, said process comprising reacting diphenylmethanediamines and polyphenylpolymethylenepolyamines (PMDA) with phosgene in the presence of at least one inert organic solvent in a two-stage reaction comprising first and second phosgenation stages, wherein the mass ratios of said phosgene to hydrogen chloride in a residence time apparatus of the second phosgenation stage are at the same time 10-30:
- 1 in the liquid phase and 1-10;
1 in the gas phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- 1 in the liquid phase and 1-10;
Specification