Preparation of emulsion homo- and copolymers and device therefore

A process for preparing homo- or copolymers of at least one of the polymerizable monomers of the group consisting of styrene, butadiene, vinyl chloride, vinyl acetate, vinylidene chloride, alkyl (meth)acrylate (meth)acrylic acid, (meth)acrylonitrile and (meth)acrylamide in an emulsion polymerization technique at at least 40° C. in the presence of a dispersing auxiliary and of a free-radical polymerization initiator, which consists essentially of preparing the polymer, at least 85% by weight of which is formed from one or more of these monomers, in the following stages, where

• a) in a first stage water is added as a solvent which is inert in the reaction, and dispersing auxiliaries, seed and a first portion of monomer(s) are added if desired,
• b) in a second stage initiator is added, and
• c) in a third stage the remainder or all of the monomer(s) is added directly or in emulsion form and in the presence of further water and, if desired, further dispersing auxiliary or other auxiliaries,
• it also being possible to operate the stages a) and b) or b) and c) as a single stage, and
• wherein the process further comprises
• in at least one of stages a) to c), moving the reaction mixture in its dispersion form by means of an external circuit which leads from and back to the reaction vessel and comprises at least one low-shear pump selected from the group consisting of nonclogging pumps which operate in accordance with the vortex principle, displacement pumps, monopumps and disc flow pumps and at least one heat exchanger having an essentially laminar flow profile, and
• carrying out polymerization at from 40 to 120° C.