Method for producing emulsion polymerisates

A method for producing emulsion polymer particles, the method comprising:

• (i) performing a sequential polymerization to obtain a multistaged emulsion polymer in the form of particles;
• ii) neutralizing the particles with at least one base to a pH of not less than 7.5, in the presence of not less than 0.5 wt % of a nonionic ethylenically unsaturated plasticizing monomer, based on the overall weight of the core-shell polymer;
• iii) subsequently polymerizing the nonionic ethylenically unsaturated plasticizing monomer optionally by further admixing one or more nonionic ethylenically unsaturated monomer;
• and
• iv) optionally polymerizing further shells comprising one or more nonionic ethylenically unsaturated monomer
• wherein:
• the multistaged emulsion polymer comprises at least a core stage polymer and a sheath stage polymer;
• the core stage polymer comprises:
• from 5 to 99.5 wt %, based on the weight of the core stage polymer, of a hydrophilic ethylenically unsaturated monomer,
• from 0 to 95 wt %, based on the weight of the core stage polymer, of at least one nonionic ethylenically unsaturated monomer, and
• 0.5 to 20 wt % of at least one nonionic polyalkylene oxide containing additive, based on the weight of the core stage polymer;
• the sheath stage polymer comprises by way of polymerized units not less than 50 wt % of a nonionic ethylenically unsaturated monomer, and
• the emulsion polymer particles produced have a whiteness above 79.

A method for producing emulsion polymer particles, the method comprising:

• (i) performing a sequential polymerization to obtain a multistaged emulsion polymer in the form of particles;
• ii) neutralizing the particles with at least one base up to a pH of not less than 7.5;
• and
• iii) optionally polymerizing further shells comprising one or more nonionic ethylenically unsaturated monomer,
• wherein:
• the multistaged emulsion polymer comprises at least a core stage polymer and a sheath stage polymer;
• the core stage polymer comprises:
• from 5 to 99.5 wt %, based on the weight of the core stage polymer, of at least one hydrophilic ethylenically unsaturated monomer,
• from 0 to 95 wt %, based on the weight of the core stage polymer, of at least one nonionic ethylenically unsaturated monomer, and
• 0.5 to 20 wt % of at least one nonionic polyalkylene oxide containing additive, based on the weight of the core stage polymer;
• and
• the sheath stage polymer comprises not less than 50 wt % of a nonionic ethylenically unsaturated monomer,
• wherein the nonionic polyalkylene oxide containing additive is selected from the group consisting of polysiloxane-polyalkylene oxide graft copolymers of comb structure, polysiloxane-polyalkylene oxide graft copolymers of α,ωstructure or mixtures thereof.