Process and apparatus for the preparation of homo- and copolymers by polymerisation in emulsion

摘要

In a process for the preparation of homo or copolymers of at least one polymerisable monomer consisting of styrene, butadiene, vinyl chloride, vinyl acetate, vinylidene chloride, alkyl(meth)acrylate, meth(acrylic)acid, (meth)acrylonitrile or (meth)acrylamide by an emulsion polymerisation technique, reaction is carried out at at least 40 degrees C in the presence of a dispersing agent and a radical initiator such that at least 85 wt.% of the polymer is prepared by (a) mixing water, inert solvent and optionally dispersing agent and optionally a portion of the monomer, (b) adding initiator and (c) adding the rest of the monomer, optionally in the form of an emulsion with further water and optionally further dispersing agent or processing aids. Steps (a) and (b) or (b) and (c) may be carried out together at 40-120 degrees C and the resulting dispersion from each step or all the steps is recirculated around a flow loop external to the reaction vessel containing a low shear pump and a heat exchanger exhibiting a laminar flow profile. An apparatus for carrying out the reaction is also claimed and comprises means for storing and feeding reactants and processing aids, a reactor vessel with a heating/cooling mantle and means for draining, an external flow loop with a low shear pump and heat exchanger exhibiting a laminar flow profile and necessary connecting pipes.