Pressure-sensitive adhesive composition comprising a dispersed polymer formed by emulsion polymerization of isobutyl acrylate, 2-ethylhexyl acrylate and/or 1-octyl acrylate, styrene and monomers having at least one acid group

A pressure-sensitive adhesive composition in the form of an aqueous polymer dispersion comprising at least one dispersed pressure-sensitive adhesive polymer formed by emulsion polymerization

• (i) from 10 to 20% by weight, based on the sum of all monomers, of isobutyl acrylate;
• (ii) from 30 to 70% by weight, based on the sum of all monomers, of 2-ethylhexyl acrylate, 1-octyl acrylate or a mixture of 2-ethylhexyl acrylate and 1-octyl acrylate;
• (iii) from 10 to 20% by weight, based on the sum of all monomers, of styrene;
• (iv) from 0.1% to 10% by weight, based on the sum of all monomers, of at least one monomer having at least one acid group;
• (v) optionally at least one (meth)acrylate alkyl ester monomer different from monomers (i) and (ii) and having, when polymerized as a homopolymer, a glass transition temperature of less than −20° C.;
• (vi) optionally at least one functional monomer selected from hydroxyl functional (meth)acrylate monomers and ureido substituted ethylenically unsaturated monomers;
• (vii) optionally at least one (meth)acrylate alkyl ester monomer different from (i), (ii) and (v);
• (viii) optionally further monomers different from (i) to (vii),
• wherein the weight ration of isobutyl acrylate (i) to 2-ethylhexyl acrylate, 1-octyl acrylate or the mixture of 2-ethylhexyl acrylate and 1-octyl acrylate (ii) is from 1:1.5 to 1:5;
• wherein the weight ration of isobutyl acrylate (i) to styrene (iii) is from 1:5 to 5:1;
• wherein the glass transition temperature of the pressure-sensitive adhesive polymer is below −20° C., determined by differential scanning calorimetry as the midpoint temperature when evaluating the second heating curve at a heating rate of 20 K/min.