The present invention is directed to a water-based acrylic emulsion
dispersant to be used as a grind resin to incorporate inorganic pigment
into a pigment dispersion for a coating composition. The acrylic emulsion
dispersant is the reaction product of butyl methacrylate, butyl acrylate,
styrene, methyl ether polyethylene glycol methacrylate, polyethylene
glycol methacrylate, and polyphosphoric acid. The present invention is
also directed to a method of preparing the acrylic emulsion dispersant. In
this method, the butyl methacrylate, butyl acrylate, and styrene are
combined with water to establish a first reaction blend. Similarly, the
methyl ether polyethylene glycol methacrylate and the polyethylene glycol
methacrylate are combined with water to establish a second reaction blend.
Next, the first and second reaction blends are polymerized to form an
intermediate emulsion polymer containing a hydroxyl group from the
functionality of the polyethylene glycol methacrylate. Finally, the
hydroxyl group from the polyethylene glycol methacrylate is reacted with
polyphosphoric acid to form the acrylic emulsion dispersant which is
utilized for efficient wetting and grinding of the pigment.
