| abstract |
It provides spray-dried powders comprising from 0.1％ to 25% a hydrophobic polymer, from 75％ to 99.9％ inorganic particles, and less than 3％ a dispersant. The Tg of the hydrophobic polymer is less than 105℃, the average particle size of the inorganic particles is from 5nm to 100um, and the average particle size of the spray-dried powders is from 1um to 400um. The hydrophobic polymer comprises, as polymerization units, an ethylenically unsaturated nonionic monomer. It further provides a process for the preparation of the spray-dried powders comprising (a) preparing a solution comprising the hydrophobic polymer, the inorganic particles, and the dispersant; and (b) adding the solution into a spray dryer and preparing the spray-dried powders. |