Patent ID: 8865115

Claim:
A process for the preparation of surface-modified nanoparticulate zinc oxide particles comprising the steps a) preparation of a solution comprising water and at least one zinc salt (solution 1 ) and a solution comprising water and at least one strong base (solution 2 ), where at least one of the two solutions 1 and 2 comprises at least one polyacrylate, wherein the polycrylate is a salt of a homopolymer of acrylic acid and has a M w in the range of from 1000 to 20000 g/mol; b) mixing the solutions 1 and 2 prepared in step a), during which the surface-modified nanoparticulate particles are formed and precipitate out of the solution to form an aqueous suspension, c) concentration of the aqueous suspension of the surface-modified nanoparticulate particles obtained in step b) by membrane filtration, where the pH of the suspension obtained in step b) and to be conveyed to step c) is in a range from 9.8 to 13, and wherein the zinc oxide concentration of the suspension obtained in step b) of zinc oxide particles in step c) is increased through membrane filtration to a value in the range from 5 to 40% by weight of zinc oxide; d) optional purification of the concentrated aqueous suspension of the surface-modified nanoparticulate particles obtained in step c), e) optionally drying of the surface-modified nanoparticulate particles obtained in step d) and f) optional thermal after treatment of the dried, surface-modified nanoparticulate particles obtained in step e).