Silica sols, a process for the production of silica sols and use of the sols
AssigneeEka Nobel AB
InventorsHans E. Johansson, Bo V. Larsson
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Abstract
Silica sols which have a large alkali excess, i.e. a low molar ratio SiO.sub.2 to M.sub.2 O, and which contain silica particles with a high specific surface area. The silica sols can be prepared through acidification of a water glass solution and subsequent alkalization of the acid sol to the molar ratio in question. The sols are particularly suitable for use as additives, in combination with cationic polymers, in papermaking.
Claims14
A process for producing paper, comprising the steps of forming a suspension of cellulose-containing fibers, adding to the suspension a cationic polymer and an anionic silica sol, forming a layer of paper from the suspension and dewatering the paper on a wire, wherein the silica sol has a molar ratio SiO to M.sub.2 O of from 6:1 to 12:1, M being an alkali metal ion or an ammonium ion, and wherein the sol contains silica particles having a specific surface area within the range of from 700 to 1200 m.sup.2 /g.
Dependencies are inferred from the claim text.