Pressure sensitive adhesive dispersion of a copolymer of butylacrylate and (meth) acrylic acid

A pressure sensitive adhesive comprising a dispersion containing a copolymer (CP) comprised of units of butyl acrylate and (meth)acrylic acid, said method consisting essentially of:

• under semi-continuous or batch polymerization conditions, polymerizing an aqueous emulsion (EM) containing butyl acrylate, an anionic emulsifier and a non-ionic emulsifier, in the aqueous phase, under heating and in the presence of at least one water-soluble initiator (IN) of formula (I)
• MR1 (I)
• where M represents an alkali metal cation, and
• R1 represents an anion of a peroxyacid or azo-group-containing acid,
• wherein said (IN) is present in an amount of 0.5-1.5 wt. % based on weight of the monomers;
• emulsifying-in (meth)acrylic acid while maintaining an elevated reaction temperature such that the ratio of butyl acrylate to (meth)acrylic acid ranges from 99.5:0.5 to 90:10 parts by wt.;
• and
• adding a second initiator (RI) to complete the polymerization and wherein said process is carried out under conditions of core and shell polymerization.