Multi-stage polymer particle having a hydrophobically-modified ionically soluble stage

Claim 1

Polymer particle comprising two or more polymer stages wherein 1) at least one of said polymer stages is an ionically-soluble polymer, said ionically-soluble polymer being polymerized from a monomer mixture comprising: a) 0.1 to 55 parts by weight based on a), b), c) and d) hydrophobic monomer having the formula; R₁ and R₅ independently are (C₁-C₃₀) alkyl, a(mono-, di-, or tri-)(C₁-C₃₀) alkyl-substituted phenyl ring, or a sorbitan fatty ester; R₂, R₃ and R₄ independently are -H or (C₁-C₁₀) alkyl, aryl or alkylaryl; a is 0 or 1; b is 0 or 1 to 50; c is 0 or 1 to 150; d is 0 or 1 to 50; e is equal to or greater than 1 and X is a group containing at least one ethylenic double bond, b) 10 to 60 parts by weight based on a), b), c) and d)(C₃-C₃₀), ethylenically-unsaturated, carboxylic acid monomer, and c) 0.1 to 90% parts by weight based on a), b), c) and d) nonionic (C₂-C₃₀) ethylenically-unsaturated monomer having the chemical formula: where Z₁ is -H, -CH₃ or Cl; Z₂ is -CN, -CI, -COOR₈, -C₆H₄R₉, - CHO, R₈ is C₁-C₁₀ alkyl or C₂-C₈ hydroxyalkyl, R₉ is -H, -Cl, -Br or C₁-C₁₀ alkyl; and R₁₀ is C₁-C₁₀ alkyl., and d) 0 to 10 parts by weight based on a), b), c) and d) multifunctional compounds; 2) said ionically-soluble polymer is grafted to said polymer particle using one or more multi-functional compounds such that, upon neutralizing said ionically-soluble polymer with base or acid, at least a portion of said ionically-soluble polymer remains attached to the remainder of said polymer particle; and 3) said polymer particle comprises from 1% to 99% by weight of said ionically-soluble polymer when in un-neutralized form or at least 0.5% by weight of said ionically soluble polymer when in neutralized form.