Production of aqueous polymer dispersions for use in adhesives, involves multi-stage emulsion polymerisation with or without adding more initiator and without cooling between stages

摘要

Aqueous polymer dispersions are produced by multi-stage emulsion polymerisation in which polymerisation in stage 2 and any further stages is carried out in presence of residual initiator from stage 1 or by adding more initiator and the temperature in the reactor is at least 70degreesC from the start of stage 1 to the end of the last stage. A method for the production of aqueous polymer dispersions by at least 2-stage aqueous emulsion polymerisation of unsaturated monomers involving (1) polymerisation of a first monomer mixture (M1) by the monomer-feed method in presence of a radical initiator (I1) to give an aqueous dispersion of polymer (P1), (2) further polymerisation by (2a) addition of a different monomer mixture (M2) in undiluted form to the dispersion and (2b) polymerisation of M2, and optionally (3) repetition of steps (2a) and (2b) in further stages (i), using a total amount of monomers (M2) which is 0.1-20 wt.% of the monomers (M1) polymerised in stage 1 and not adding (M2) before the addition of (M1) is complete. In this method, (a) polymerisation in stage 2 (and any further stages) is carried out in presence of residual initiator (I1) or by adding more (I1) and (b) the temperature in the reactor is at least 70degreesC from the start of stage 1 to the end of step 2b in the last stage. Independent claims are also included for (1) aqueous polymer dispersions obtained by this method (2) polymer powder obtained by evaporating volatile components from these dispersions.