Process for the production of polyisocyanate-polyaddition products using a multi-phase reaction flow tube

Claim 1

A continuous process for the production of polyisocyanate-polyaddition products by reacting starting reaction components (A) polyisocyanates with (B) compounds containing at least two isocyanate-reactive groups in the presence of a material selected from the group consisting of organic solvents or dispersants, inert carrier gases, and mixtures thereof, comprising (1) introducing the liquid mixture of the starting reaction components, in the form of a solution or dispersion or with an inert carrier gas, into a coil flow tube having an internal diameter of from 3 to 100 mm, a ratio of tube diameter to tube length of from 1:100 to 1:3,000 and a ratio of tube diameter to coil diameter of from 1:5 to 1:100, the fall in pressure over the length of the reaction tube amounting to from 10 mbars to 100 bars, the quantitative ratios of starting reaction components, solvents or dispersants, and inert carrier gas being selected in such a way that the proportion of the total gas phase in the reaction tube amounting to from 10 to 90%, by weight, the rate of gas flow in the tube amounting to from 20 to 300 meters/second and the average residence time of the reacting starting components in the tube amounting to less than 5 minutes; directly dissipating the generated heat of reaction through the tube jacket which is coolable or heatable in sections, so that the reaction temperature is from 20° to 250° C.; (2) removing the solid and/or liquid reaction product, and the inert carrier gas and/or vapor-formed solvent or dispersant at the end of the reaction tube.