Amphoteric polymer particles and compositions thereof

A stable aqueous dispersion of multiphase amphoteric polymer particles comprising:

• a) a crosslinked polymer phase comprising, based on the weight of the crosslinked polymer phase:
• i) from 1 to 10 weight percent structural units of a phosphorus acid monomer or a salt thereof;
• ii) from 0.5 to 5 weight percent structural units of a carboxylic acid monomer or a sulfur acid monomer or a salt thereof or a combination thereof;
• iii) from 1 to 10 weight percent amine groups or salts thereof or quaternary ammonium salts;
• iv) 0.1 to 20 weight percent structural units of a multiethylenically unsaturated monomer;
• and
• v) from 80 to 97 weight percent structural units of an ethylenically unsaturated nonionic monomer;
• and
• b) a second polymeric phase comprising:
• i) from 0.1 to 4 weight percent structural units of a carboxylic acid monomer or a sulfur acid monomer or a salt thereof or combination thereof;
• and
• ii) from 80 to 99.9 weight percent structural units of an ethylenically unsaturated nonionic monomer;
• wherein the crosslinked polymer phase protuberates from the second polymer phase;
• wherein the weight:weight ratio of the crosslinked polymer phase to the second polymer phase is in the range of from 1:4 to 1:99;
• with the proviso that the multiphase amphoteric polymer particles comprise from 0.01 to 4 weight percent structural units of the phosphorus acid monomer or a salt thereof and from 0.01 to 4 weight percent of the amine groups or salts thereof or the quaternary ammonium salt groups.