Use of poly(2-Vinylpyridine)-b-poly(epsilon-caprolactone) copolymers as pigment stabilizers in powder coatings

Four poly(2-vinylpyridine)-b-poly(e-caprolactone) copolymers, differing in buoy block length and anchor/buoy block length ratio, have been used as TiO2 pigment dispersants in a polyester powder coating resin. When the TiO2 surface was fully covered with the block copolymers, the colloidal stability of the TiO2 dispersions at typical curing temperatures was significantly improved because of the formation of a steric layer around the pigment particles. As a result, powder coatings with excellent flow, high gloss, and low haze values were obtained. Because of the high affinity of the dispersants for the TiO2 surface, pretreatment of the pigments with the block copolymers was not necessary. At full pigment surface coverage, the chain length of the stabilizing polymer had little effect on the performance of the dispersants used.