Silica-based sols
US7169261B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 5, 2001 |
| Grant date | Jan 30, 2007 |
| Priority date | — |
| Expiry date | Nov 5, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B33/146
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An aqueous sol containing silica-based particles which has an S-value within the range of from 10 to 45%, a viscosity within the range of from 5 to 40 cP, and a molar ratio of SiO2 to M2O, where M is alkali metal or ammonium, within the range of from 10:1 to 40:1, or a silica content of at least 10% by weight. The invention further relates to a process for the production of silica-based particles comprising the steps of: (a) acidifying an aqueous silicate solution to a pH of from 1 to 4 to form an acid sol; (b) alkalising the acid sol at an SiO2 content within the range of from 4.5 to 8% by weight to; (c) allowing particle growth of the alkalised sol for at least 10 minutes, or heat-treating the alkalised sol at a temperature of a least 30° C.; and then (d) alkalising the obtained sol to a pH of at least 10.0. The invention further relates to silica-based particles obtainable by the process, the use of the silica-based particles as drainage and retention aids in the production of paper as well as a process for the production of paper from an aqueous suspension containing cellulosic fibers, and optional filler, in which silica-based particles and at least one charged organic polymer…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.