The present invention provides a process for the preparation of polymer which comprises the steps of i) feeding an aqueous mixture comprising a monoethylenically unsaturated monomer or a mixture of monoethylenically unsaturated monomers and an initiator into the top of a reactor ii) polymerizing the monoethylenically unsaturated monomer to form a gel-like aqueous mixture comprising the polymer, iii) squeezing the gel-like aqueous mixture comprising the polymer out of the bottom of the reactor using inert gas, wherein the reactor is either a vertical fully conical reactor having an angle (alpha) between top diameter (d1) of the reactor and inner wall of the reactor of smaller than 90° but larger than 45° or is made up of 2 to 5 connected vertical fully conical parts, which are on top of one another, each having an angle between top diameter of the part and inner wall of the part of smaller than 90° but larger than 45°.