Dispersion Of Nano-CaCO₃ In Water And Preperation Of A Hyperdispersant

As an important functional material, nano-CaCO3 have been more widely used in paper, plastic, printing ink, rubber, paint and other industries. However, its aggregation problem has severely restricted the development of the industry, because of its larger surface area and high surface energy. So that, a suitable dispersing agent is needed to disperse nano-CaCO3 satisfactorily, and stabilize particle size in the nanometer level, which is the key of the widespread application of nano-CaCO3 in many aspects.Determination of gravity sedimentation, fineness and viscosity were employed to characterize 52%(wt) nano-CaCO3 slurry, which were respectively dispersed by four kinds of dispersant SDBS, PAANa, TH-904 and B-02. Then the influences of those parameters such as dispersant dosage, dispersion method and the pH value'of suspension were discussed, with the purpose of getting better dispersion conditions. By comparison, TH-904 is the optimal dispersing agent to disperse nano-CaCO3, and the viscosity of nano-CaCO3 slurry is as low as 28 mPa-s.According to the surface properties of nano-CaCO3, and the mechanism of hyperdispersant, a kind of hyper-dispersant was polymerized in aqueous solution, by using acrylic acid (AA), methyl propylene sulfonate (SMAS) and maleic anhydride (MAn) as the monomers. The orthogonal and single factor experiments for optimizing raw material proportion show when the monomer mass ratio is AA:MAn:SMAS= 10:3:3, the total water is 120% of total monomers mass, the initiator is 8%, the hyper-dispersant is better to disperse 52%(wt) nano-CaCO3 slurry. The dispersion is well-distributed and no significant changes in standing for one months, moreover, the dispersion viscosity is as low as 13.1mPa-s.The molecular weight of self-made dispersant is 3091. After being dispersed by this dispersant, the nano-CaCO3 were characterized by SEM and IR, the result show that the dispersant has a good adsorption ability for nano-CaCO3, moreover, nano-CaCO3 particles have clear outline, little reunion. So the hyper-dispersant has a greatly effect on the dispersion of nano-CaCO3, and it is good for preparing nano-CaCO3 solution of high solid content.