Static mixer and method for mixing a main component with an additive

摘要

The invention relates to a static mixer ( 1 ) having a cylindrical mixer channel formed by a mixer channel housing ( 5 ) and a multistage mixer blade element ( 3 ) which is disposed in said mixer channel and used for mixing layers of hardening accelerator paste in a stream of highly viscous PU. Discharge openings ( 7 ) are provided in the inlet area of the static mixer. Said discharge openings introduce a partial stream of hitherto unmixed highly viscous PU into. secondary channels ( 6 ) disposed parallel to the mixer channel. The secondary channels are connected to feeder openings ( 8 ) disposed in the wall of the mixer channel downstream of the mixer wing element ( 3 ) when viewed in the direction of flow. The unmixed PU is guided in the secondary channels ( 6 ) and enters the outer area of the stream coming from the mixer wing element via the feeder openings where the mixed layers of hardening accelerator paste are contained. The mixed stream is jacketed with a layer of unmixed PU to prevent layers of hardening accelerator paste from being discharged from an adhesive element applied with the aid of the mixer ( 1 ) and to prevent the occurrence of adhesive defects resulting therefrom.