The invention relates to a copolymer that can be used as wetting agent and dispersant and contains i) 40-73 mole percent of a base structural unit (A) and ii) 27-60 mole percent of a substituted dicarboxylic acid derivative structural unit (B), the structural unit (B) containing species having a bisamide structure and species having quaternized amino groups.

This invention generally relates to a multi-stage polymer as a grinding additive and a method of producing the same.