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. The method comprises the steps of a.) loading the first volume of the vessel with an initial amount of polymer, optionally water and optionally alkaline; b.) heating the vessel externally to a target process temperature in the range of 80-300 DEG 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.) adding water and optional alkaline to the first volume; e.) connecting 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 ratio 3 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.