Patent ID: 7723436

Claim:
A process for preparing a polyacrylate having an at least bimodal molecular weight distribution, which comprises polymerizing a monomer mixture of a1) 70% to 100% by weight acrylic acid and/or acrylic esters of the formula CH 2 ═C(R′)(COOR 2 ), where R′═H or CH 3 and R 2 is an alkyl chain having 1 to 20 carbon atoms, and a2) 0 to 30% by weight olefinically unsaturated monomers containing functional groups, in an at least two-phase free-radical solvent polymerization in the presence of an organic solvent or in mixtures of organic solvents to give a polyacrylate having an at least bimodal molecular weight distribution, the polymerization being carried out in a first phase of the at least two-phase polymerization, in the presence of a first initiator concentration, to give a first polymer having a first molecular weight and, before the monomer mixture has been completely consumed by the polymerization, a further phase or phases of polymerization is or are started, by the addition at least once of a regulator, and in this further phase or further phases a second polymer or polymers is or are synthesized, said second polymer having a second molecular weight which second molecular weight is lower than said first molecular weight.