| abstract |
SUMMARY OF THE INVENTION The present invention relates to polysilicate microgels, their preparation and use in papermaking and water purification, wherein the polysilicate microgel comprises contacting (i) particles of a salt AB with an aqueous silicate or polysilicate solution. (Ii) contacting ion A with ion B in the presence of an aqueous silicate or polysilicate solution (whereby AB is precipitated in the aqueous phase), or (iii) in the presence of an aqueous silicate or polysilicate solution. Contacting ion A with ion B (wherein ions A and B correspond to ions of a precipitable salt AB having a pK s value of at least 4 measured in water at 20 ° C.). Can be The invention further relates to aqueous silicate or polysilicate solutions, their preparation and use as precursors of polysilicate microgels. The aqueous silicate or polysilicate solution contains ions A, which are calcium or magnesium ions, wherein the molar ratio of SiO 2 : A is less than 2000: 1 and more than 1: 1, or ions which are carbonate, sulfate or phosphate ions. B, and the molar ratio of SiO 2 : B is less than 2000: 1 and more than 1: 1. |