| abstract |
It has been found that quaternary onium (e.g., ammonium, sulfonium, and phosphonium) salt group-containing epoxy resins are particularly useful as grinding media in preparing stable pigment disperions useful in water-dispersible coating systems, for example, electrodepositable compositions. The resins are prepared by reacting a material selected from the group consisting of amine salts, phosphine-acid mixtures, and sulfide-acid mixtures with a 1,2-epoxy group containing material wherein a ratio of at least about 0.4 eqivalents of quaternary onium groups are produced per equivalent of epoxy group initially present. Preferably, the system contains at least a small amount of polyoxyalkylene glycol. |