Bimodal acrylate pressure-sensitive adhesive compounds

A pressure-sensitive adhesive comprising a polyacrylate obtained by the process of polymerizing a monomer mixture of

• a1) 70% to 100% by weight acrylic acid and/or acrylic esters of the formula CH2═C(R′)(COOR2), where R′═H or CH3 and R2 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
• comprising the following monomer units:
• a1) acrylic acid and/or acrylic esters of the formula CH2═C(R′)(COOR2), where R′═H or CH3 and R2 is a linear, branched or cyclic alkyl chain having 1 to 20 carbon atoms,
• at 70%-100% by weight, based on the polymer,
• a2) olefinically unsaturated monomers containing functional groups, at 0-30% by weight, based on the polymer,
• and having a broad, at least bimodal molecular weight distribution, the molecular weight maxima in the molecular weight distributions of at least two polymers being at least 50 000 g/mol apart.