disclosed is a method for the production of thermoplastic polymer dispersions , using a reaction vessel with a first volume and a secondary volume , wherein a first stirrer is located and operative in said first volume and a secondary stirrer is located and operative in said secondary volume , wherein the first volume is at least 20 times larger than the secondary volume , wherein the stirrers in both volumes are able to handle viscosities above of or equal to 1000 mpas , including the steps of a .) loading the first volume of the vessel with an initial amount of polymer and optionally water and optionally alkaline ; b .) heating the vessel externally to a target process temperature in the range of 80 - 300 ° c . ; c .) operating the first stirrer in the first volume for at least half an hour at a speed of in the range of 10 - 100 rpm ; d .) addition of water and optionally alkaline to the first volume ; e .) connection of the secondary volume to the first volume and operating the secondary stirrer in the secondary volume at a speed of above 1000 rpm and recycling the reaction product through said secondary stirrer while keeping the operating temperature essentially constant during a timespan in excess of the recycle ratio3 of the primary and the secondary mixer to form the dispersion . furthermore disclosed is a dispersion as obtainable using such a method and a reaction vessel for carrying out such a method .