Akzo Nobel N.v.

Akzo Nobel Chemicals International B.v.

Eka Chemicals Ab

Nouryon Chemicals International B.v.

Akzo Nobel Pulp and Performance Chemicals Ab

Erik Sanne

Johan Nyander

Rune Kjell Andersson

Freddie Hansson

Kjell Rune Andersson

Peter Marten Van Der Horst

Marie-Louise Wallberg

Sune Wännström

Cherryleen Garcia-Lindgren

Peter Marten Horst Van Der

Kjell Andersson

The present invention relates to a silica sol having a pH above about 10, molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, concentration of soluble silica above about 3000 mg SiO2/l, and S-value of from about 18 to about 40%. The invention further relates to a process for producing a silica sol which comprises acidifying an aqueous alkali metal silicate solution to a pH of from 1 to 4 to form an acid sol, alkalizing the acid sol by addition of aqueous alkali metal silicate solution to obtain an intermediate sol and interrupt the addition of aqueous alkali metal silicate solution when the intermediate sol has reached a pH of from about 5 to about 8, stirring the intermediate sol for a time period of from about 10 to about 6000 seconds without addition of aqueous alkali metal silicate solution, alkalizing the intermediate sol by addition of aqueous alkali metal silicate solution to obtain a silica sol having a pH above about 10 and molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, and optionally adding an aluminum compound to the acid sol, intermediate sol or silica sol. The invention further relates to a silica sol obtainable by the process of the invention. The invention further relates to the use of the silica sol as a flocculating agent, in water purification and in producing paper and board. The invention further relates to a process for producing paper and board which comprises: (i) providing an aqueous suspension comprising cellulosic fibers; (ii) adding to the suspension one or more drainage and retention aids comprising the silica sol; and (iii) dewatering the obtained suspension to provide a sheet or web of paper or board.

Silica sol

The present invention relates to a filler comprising clay and cellulose derivative having a degree of substitution of net ionic groups up to about 0.65.

Filler for paper making process

The present invention relates to a filler comprising calcium salt and cellulose derivative having a degree of substitution of net ionic groups up to about 0.65, wherein the filler is substantially free from fibers or fibrils of cellulose or lignocellulose. The invention also relates to a filler comprising calcium salt and a cellulose derivative having a degree of substitution of net ionic groups up to about 0.65, wherein the cellulose derivative contains cationic groups.

Filler for papermaking process

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Mölndal, Sweden

Erik Sanne