Aqueous dispersion comprising multistage polymeric particles

An aqueous dispersion comprising:

• (i) multistage polymeric particles having a Tg in the range of from 0 to 80° C. and comprising a polymer A in a first stage and a polymer B in a second stage at a weight ratio of the polymer A to polymer B in the range of from 78:22 to 22:78,
• wherein the Tg difference between the polymer A and the polymer B is 40° C. or more and the Tg of polymer A is higher than the Tg of polymer B, and
• wherein the multistage polymeric particles comprise, by weight based on the weight of the multistage polymeric particles,
• (a) from 10% to 40% of structural units of a cycloalkyl(meth)acrylate,
• (b) from 40% to 85% of structural units of a hydrophobic monomer,
• (c) from 0.5% to 10% of structural units of an ethylenically unsaturated monomer carrying at least one functional group selected from a carboxyl, carboxylic anhydride, sulfonic acid, amide, sulfonate, phosphoric acid, phosphonate, phosphate, or hydroxyl group, or a salt thereof,
• (d) structural units of a polymerizable surfactant having the structure of formula (I),
• wherein R1 is a phenyl group or a phenyl substituted alkyl group;
• m1 is 1, 2, 3 or 4, R2 is an alkyl group or a substituted alkyl group;
• m2 is 0 or 1;
• R3 is a hydrogen atom;
• an alkyl group;
• or —C(R4)═CR5R6, wherein R4, R5, and R6 are each independently hydrogen or an alkyl group having 1 to 22 carbon atoms;
• A represents an alkylene group or a substituted alkylene group, having 2 to 4 carbon atoms;
• n is an integer of from 1 to 100;
• and X represents hydrogen or an anionic hydrophilic group selected from —(CH2)a—SO3M, —(CH2)b—COOM, —PO3M2, —P(Z)O2M, or —CO—CH2—CH(SO3M)—COOM, wherein a and b are each independently an integer of from 0 to 4, Z represents a residual obtained by removing X from the general formula (I), and each M represents hydrogen, an alkali metal cation, an alkaline earth metal cation, NH4±, an aminium ion having an ethylenically unsaturated bond, an imidazolium ion having an ethylenically unsaturated bond, a pyridinium ion having an ethylenically unsaturated bond, a pyrrolidinium ion having an ethylenically unsaturated bond, or a piperidinium ion having an ethylenically unsaturated bond;
• provided that only one of R3 and X contains an ethylenically unsaturated bond;
• and optionally
• (e) structural units of an additional ethylenically nonionic monomer;
• wherein the multistage polymeric particles are admixed with (ii) from 0.1 to 5%, by weight based on the weight of the multistage polymeric particles, of a metal salt.