METHOD AND DEVICE FOR PRODUCING POLYMER DISPERSIONS

摘要

The invention relates to a method for producing polymer dispersions of at least one of the monomers that can be polymerized from the following groups: alkyl(meth)acrylates, vinyl esters of carboxylic acids comprising 1-20 C atoms, vinyl aromatic compounds, nitriles, vinyl halides, vinyl ethers, hydrocarbons comprising 2-8 C atoms and monomers containing hydroxyl groups, using emulsion polymerization technology at a polymerization temperature of at least 40 DEG C in the presence of a radical polymerization initiator. The polymer which is produced from at least 85 wt. % of one or several of said monomers is produced in the following way: in a first stage, water, which acts as an inert solvent during the reaction, optionally a dispersant, seed particles and optionally a first sub-quantity of the monomer(s) are added. In a second stage, the initiator is added. In a third stage, the remaining quantity or the total quantity of the monomer(s) is added directly or in the form of an emulsion in the presence of additional water. The first and second stages, or the second and third stages respectively can be carried out as a single-stage, whereas the second and third stages can also be carried out in a gradient operation. In individual or all stages of the reaction mixture that is present as a dispersion, said mixture is displaced by an external circuit (10) that leads from and returns to the polymerization container (2). The circuit comprises one or more hose or cylinder diaphragm pumps (7), which transport the product with a low shear rate and at least one heat exchanger (8), whereby the polymerization temperature lies between 40 DEG C and 120 DEG C.