SILICON DIOXIDE BASED SOLS, THEIR PREPARATION AND USAGE Russian patent published in 2009 - IPC C01B33/143 

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry and paper production. The method for preparation of aqueous silica-based sol includes aqueous suspension formation by the interreaction of the ion-exchange resin in hydrogen form with aqueous alkali metal silicate. The obtained aqueous suspension is mixed until pH of aqueous phase settles in the range 5.0-11.5 and/or microgel forming corresponding S value less than 45% and pH of aqueous phase achieving the value no less than 5.0. After that pH of aqueous phase is brought up to value higher than 9 using at least one aluminium compound. The ion-exchange resin is separated from aqueous phase either after pH achieving the range 5.0-11.5 or after microgel formation corresponding S value less than 45% and pH of aqueous phase achieving the value no less than 5.0, or after pH exceeding the value 9. The obtained sol has S value in the range 15-25%, mole ratio Si : Al in the range from 20 : 1 to 50 : 1, mole ratio Si : X, wherein X = alkali metal, in the range from 5 : 1 to 17 : 1, content of SiO₂ no less than 5 wt %. The silica-based particles have the specific surface area at least 300 m²/g.

EFFECT: proposed method allows to obtain the silicon dioxide based sol with improved characteristics for its using in paper production as dewatering agent and retention aid.

29 cl, 4 tbl, 8 ex