An Improved Method for making an aqueous dispersion

摘要

The invention relates to a method for preparing aqueous dispersions, especially electrodepositable aqueous dispersions. The invention requires the use of a polymer (a) comprising one or more water dispersible groups per molecule and one or more functional groups (f), and at least one crosslinking agent (b) comprising one or more blocked functional groups (fb) reactive with polymer (a) after unblocking. Crosslinking agent (b) has a Tg of from 40 to 70° C./105 to 158° F. and is a solid at 23.9° C./75° F. when at 100% by weight solids. Crosslinking agent (b) is mixed into polymer (a) at a temperature at or above the melting temperatures of both polymer (a) and compound (b) but below the temperature at which blocked functional groups (fb) unblock. Sufficient water is added to the resulting melt-mixture (ii) to provide an aqueous dispersion.