SILICON DIOXIDE-BASE SOLS Russian patent published in 2003 - IPC

FIELD: chemical technology. SUBSTANCE: invention relates to methods for preparing an aqueous sol containing particles based on silicon dioxide. Method involves the following stages: (a) acidification of silicate an aqueous solution to pH from 1 to 4; (b) alkalinization of acidic sol at content of SiO₂ in the range from 4.5 to 8 wt.-%: (c) providing the growth of alkaline sol particles for at least 10 min and heat treatment of alkaline sol at temperature 30 C, not less; (d) alkalinization of prepared sol to pH 10.0, not less; (e) optional concentrating sol prepared in accordance to stages (b), (c) or (d). Specific surface of prepared sol is at least 90 m²/g. Invention relates also to an aqueous sol containing particles based on silicon dioxide and indicated sol has specific surface 115 m²/g, not less, and S-value in the range from 10 to 45% or contains particles based on silicon dioxide with specific surface 550 and less than 1 000 m²/g SiO₂. The above said sol is used as agent for drainage and retention in production of paper. In method for production of paper from an aqueous suspension containing cellulose fibers and filling agents optionally an aqueous sol is used that is added to cellulose suspension being this sol contains particles based on silicon dioxide and at least one charged organic polymer. Sols and particles based on silicon dioxide show the improved capacity for retaining high specific surface in storage and result to the improved drainage. EFFECT: improved and valuable properties of sols. 27 cl, 3 tbl