The ultra-fine CaCO_3 coated with acrylic acid monomer and the polyacrylic aid with varied molecular weight was prepared. The influences of the chemical properties of the treating agent, the treatment method and conditions on the coating efficiency were investigated. The tropism and arrangement of the treating molecules on the surface greatly affected the dissolving curves observed, which was proved by IGC and XPS analysis. Maximum efficacy was expected at the monolayer coverage and it's coating amount was about 0.6 wt% according to the calculations based on the alignment mode which was in agreement with the results deduced from the molar ratio of O/Ca and C~(290)/Ca and inferred from the dissolving curves. The interaction mechanism between carboxyl group and calcite surface was also preliminary elucidated from the point of view of O/Ca and C~(290)/Ca molar ratio.

Key words: calcium carbonate, polyacrylic acid, surface treatment, XRD, CLADDING, INTERACTIONS