SILICA-BASED SOLS AND THEIR PRODUCTION AND USE

摘要

The present invention relates to a silica-based sol having an S value within the range of from 15 to 25 %, mole ratio Si:Al in the range of from 20:1 to 50:1, mole ratio Si:X, where X = alkali metal, in the range of from 5:1 to 17:1, SiO 2 content of at least 5 % by weight and containing silica-based particles having a specific surface area of at least 300 m 2 /g. The invention further relates to a process for producing paper which comprises (i) providing an aqueous suspension comprising cellulosic fibres; (ii) adding to the suspension one or more drainage and retention aids comprising a silica-based sol according to the invention; and (iii) dewatering the obtained suspension to provide a sheet or web of paper.