Silica sols and use of the sols
AssigneeEka Nobel AB
InventorsKjell Andersson, Bo Larsson, Erik Lindgren
Life of this patent
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Abstract
Silica sols with a high content of microgel and particles with a specific surface area within the range 300 to 700 m.sup.2 /g, preferably 400 to 650 m.sup.2 /g. The sols can be prepared by acidification or a water glass solution and alkalization at a certain dry content, alternatively to a certain pH. The sols are particularly suitable for use as additives in papermaking in combination with cationic polymers and especially in combination with cationic acrylamide based polymers.
Claims17
Silica sols having an S-value within the range from 15 to 40 percent comprising anionic silica particles, said silica particles being non-aluminum modified, and having a specific surface area within the range of from 300 to 700 m.sup.2/ g.
A process for the production of paper, which comprises:
- (a) providing a suspension containing cellulose fibers, and optional fillers;
- (b) adding to said suspension a cationic or amphoteric polymer retention and/or dewatering aid, said polymer being added in an amount of at least 0.01 kg/ton, based on dry fibers and optional fillers;
- (c) adding to said suspension a silica sol comprising anionic silica particles, said silica particles being non-aluminum modified and having a specific surface area within the range of from 300 to 700 m.sup.2 /g, said silica sol having an S-value within the range of from 15 to 40 percent, wherein said silica sol is added to the suspension in an amount of at least 0.01 kg/ton, calculated as SiO.sub.2 on dry fibers and optional fillers;
- and
- (d) thereafter forming and dewatering the obtained suspension on a wire to form paper.
Silica sols having an S-value within the range of from 15 to 40 percent comprising anionic silica particles, said silica particles being aluminum modified and having a specific surface area within the range of from 300 to 700 m.sup.2 /g.
A process for the production of paper which comprises
- (a) providing a suspension containing cellulose fibers, and optional fillers;
- (b) adding to said suspension a cationic or amphoteric polymer retention and/or dewatering aid, said polymer being added in an amount of at least 0.01 kg/ton, based on dry fibers and optional fillers;
- (c) adding to said suspension a silica sol comprising anionic silica particles, said silica particles being aluminum modified and having a specific surface area within the range of from 300 to 700 m.sup.2 /g, wherein said silica sol has an S-value within the range of from 15 to 40 percent and said silica sol is added to the suspension in an amount of at least 0.01 kg/ton, calculated as SiO.sub.2 on dry fibers and optional fillers;
- and
- (d) thereafter forming and dewatering the obtained suspension on a wire to form paper.
Dependencies are inferred from the claim text.