SILICA-BASED SOLS Russian patent published in 2004 - IPC

FIELD: paper-and-pulp industry.

SUBSTANCE: invention relates to aqueous sol containing silica-based particles and to papermaking process. Aqueous sol has S value within a range of 10 to 45%, viscosity 5 to 40 cPs, and SiO₂/M₂O molar ratio from 10:1 to 40:1, where M represents alkali metal or ammonium, and silica content is at least 10 wt %. Silica-based particles are prepared as follows: aqueous solution of a silicate is acidified to pH 1-4 resulting if formation of sol containing 4.5-8 wt % silica, which sol is subjected to first-step alkalization to pH at least 7 leading to growth of alkaline sol particles for at least 10 min. Sol is the thermally treated and subjected to second-step alkalization to pH al 10.0. Manufacture of paper from aqueous slurry containing cellulose fibers and optionally filler comprises adding silica-based particles and at least one charged organic polymer.

EFFECT: improved drainage and retention properties and increased stability of sol.

20 cl, 3 tbl, 7 ex