Method for preparing polyisochanate, polyisochanate prepared by this method

Abstract

This paper proposes a method for preparing polyisocyanates, the polyisocyanates obtained using this method, and the reaction apparatus used in this method. This method includes the following steps: ]) adding polyamine solution and phosgene solution to the cold reaction of the phosgene reaction; and 2) adding the material from step 1) to the hot reaction, where the amount of monofunctional impurities generated in step 1) is controlled so that the content of monofunctional impurities in the finished product is from 0.1 ppm to 20000 ppm, and the amount of polyfunctional impurities generated in step 2) is controlled so that the content of polyfunctional impurities in the finished product is from 0.1 ppm to 1000 ppm. In this invention, by controlling the content of monounsaturated and polyunsaturated impurities in the cold and hot reaction stages, respectively, solvent consumption is controlled, thus significantly reducing energy consumption.