Process for the preparation of polyurethane prepolymers containing isocyanate groups

Process for the preparation of a prepolymer containing isocyanate groups from a component containing isocyanate groups and an isocyanate-reactive component groups, characterized in that the components are mixed continuously in a mixing device and the reaction mixture immediately after the it mixed is introduced continuously in a storage container or transport, where the reaction is completed between the components, wherein in a first stage of a batch production driving first-component containing isocyanate groups by the device mixer to the vessel before a second stage the isocyanate-reactive component groups in addition to the component containing isocyanate groups also to the mixing device, where it mixes with the first reaction component, and wherein to finish production is conducted batch dosing component is interrupted rea or isocyanate groups and the mixing device is washed with the component containing isocyanate groups.