Akzo Nobel N.v.

Eka Nobel Ab

Eka Chemicals Ab

Marek T Tokarz

Michael Persson

Maj-Lis Dahlgren

Sven G Jaras

Rein Sikkar

Hans Erik Johansson-Vestin

Freddie Hansson

Glenn Mankin

Roman Kozlowski

Borje Persson

Erik Lindgren

Hans E Johansson

Kjell Rune Andersson

Patrik Simonson

Hans-Åke Baltsen

Katarina Gutke

Jerker Nilsson

An aqueous sol containing silica-based particles which sol has a specific surface area of at least 115 m/g aqueous sol and a pH of at least 10.5, and an S-value within the range of from 10 to 45% and/or contains silica-based particles having a specific surface area of at least 550 and less than about 1200 m/g SiO, and wherein the sol is substantially free from aluminium.

Silica-based sols

The present invention relates to a silica-based sol having a concentration of soluble silica of less than about 1000 mg SiO/l, conductivity of at least about 2.0 mS/cm and S-value below about 50%. The invention further relates to a method of producing a silica-based sol comprising subjecting an aqueous alkali metal silicate solution to electrodialysis to form an electrodialyzed sol, and acidifying the electrodialyzed sol to form an acidified sol having a pH in the range of from about 5.0 to about 10. The invention further relates to silica-based sol obtainable by the process and to the use of the silica-based sol as a flocculating agent. The invention further relates to a process for producing paper which comprises providing an aqueous suspension comprising cellulosic fibers, adding to the suspension one or more drainage and retention aids comprising a silica-based sol according to the invention, and dewatering the obtained suspension to provide a sheet or web of paper.

The present invention relates to a process for the production of a cellulosic product which comprises providing an aqueous thick suspension containing cellulosic fibers having a fiber concentration of at least about 2% by weight; adding to the thick suspension an aluminum compound, alkaline earth metal salt and acid; diluting the obtained thick suspension to form a thin suspension; adding to the thin suspension one or more drainage and retention aids; and dewatering the obtained thin suspension. The invention further relates to a process for the production of a cellulosic product which comprises providing an aqueous thick suspension containing cellulosic fibers having a fiber concentration of at least about 2% by weight and an alkaline earth metal ion concentration of at least about 100 mg/l; adding to the thick suspension an aluminum compound and optionally an acid to obtain a pH of from about 4 to about 5.5; diluting the obtained thick suspension to form a thin suspension; adding to the thin suspension one or more drainage and retention aids; and dewatering the obtained thin suspension. The invention also relates to an aqueous composition comprising a mixture of an aluminum compound, alkaline earth metal salt and acid and the use of the composition.

Process for the production of cellulosic product

The invention relates to an aqueous sol containing silica-based particles which sol has a specific surface area of at least 115 m/g aqueous sol and an S-value within the range of from 10 to 45% or contains silica-based particles having a specific surface area of at least 550 m/g and less than 1000 m/g SiO. The invention further relates to processes for the production of said aqueous sol and the use of the aqueous sol containing silica-based particles as a drainage and retention aid in the production of paper as well as a process for the production of paper from an aqueous suspension containing cellulosic fibres, and optional filler, in which silica-based particles and at least one charged organic polymer are added to the cellulosic suspension.

The invention relates to a process for producing aqueous silica-based sols which comprises providing a cationic ion exchange resin having at least part of its ion exchange capacity in hydrogen form; bringing said ion exchange resin in contact with an aqueous alkali metal silicate to form an aqueous slurry; adjusting the pH of the aqueous slurry and separating the ion exchange resin from the aqueous slurry, as well as the silica-based sols obtained by the process; the invention also relates to silica-based sols obtained by the process, as well as a process for producing paper which comprises providing an aqueous suspension comprising cellulosic fibres; adding to the suspension one or more drainage and retention aids comprising a silica-based sol according to the invention; and dewatering the obtained suspension to provide a sheet or web of paper.

Silica-based sols and their production and use

The invention relates to a process for producing aqueous silica-based sols which comprises providing a cationic ion exchange resin having at least part of its ion exchange capacity in hydrogen form; bringing said ion exchange resin in contact with an aqueous alkali metal silicate to form an aqueous slurry; adjusting the pH of the aqueous slurry and separating the ion exchange resin from the aqueous slurry, as well as the silica-based sols obtained by the process. The invention also relates to silica-based sols obtained by the process, as well as a process for producing paper which comprises providing an aqueous suspension comprising cellulosic fibres; adding to the suspension one or more drainage and retention aids comprising a silica-based sol according to the invention; and dewatering the obtained suspension to provide a sheet or web of paper.

A process for the production of paper which includes the steps of providing an aqueous suspension containing cellulosic fibers, and optional fillers; adding to the suspension: (a) at least one charged organic polymer; and (b) an aqueous sol containing silica-based particles; wherein the sol has: (i) an S-value within the range of from 10 to 45%; (ii) a viscosity within the range of from 5 to 40 cP; and (iii) a molar ratio of SiOto MO, where M is alkali metal or ammonium, within the range of from 10:1 to 40:1; and (III) forming and draining the suspension on a wire. The invention is further directed to processes for making paper wherein the added sol has: (i) an S-value within the range of from 10 to 45%; (ii) a viscosity within the range of from 5 to 40 cP; and (iii) a silica content of at least 10% by weight, or wherein the added sol has: (i) an S-value within the range of from 10 to 45%; (ii) a viscosity within the range of from 7 to 25 cP; (iii) a silica content of at least 10% by weight; (iv) a molar ratio of SiOto MO, where M is alkali metal or ammonium, within the range of from 10:1 to 40:1; and (v) a pH of at least 10.6. The invention is further directed to a process for making paper wherein the added sol is modified by an aluminum-containing compound, a boron-containing compound or a mixture thereof and has: (i) an S-value within the range of from 10 to 45%; (ii) a viscosity within the range of from 5 to 40 cP; (iii) a silica content of at least 10% by weight; and (iv) a molar ratio of SiOto MO, where M being alkali metal or ammonium, within the range of from 10:1 to 40:1.

Production of paper using slica-based-sols

The present invention relates to a process for the production of a cellulosic product which comprises (i) providing an aqueous cellulosic suspension; (ii) adding to the suspension a clay having 3Rstacking; and (iii) dewatering the obtained suspension. The invention also relates to a process for the production of a cellulosic product which comprises (i) providing an aqueous cellulosic suspension; (ii) adding to the suspension a cationic clay; (iii) adding to the suspension one or more drainage and retention aids comprising at least one cationic polymer; and (iv) dewatering the obtained suspension. The invention further relates to a cellulosic product comprising clay having 3Rstacking.

Cellulosic product and process for its production

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 SiOto MO, 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 SiOcontent 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&#xb0; 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 are added to the cellulosic suspension.

The present invention relates to polysilicate microgels, their preparation and use in paper making and water purification, the polysilicate microgels being obtainable by a process which comprises bringing into contact (i) particles of a salt AB with an aqueous silicate or polysilicate solution, (ii) an ion A with an ion B in the presence of an aqueous silicate or polysilicate solution, whereby the salt AB is precipitating in the aqueous phase, or (iii) an ion A with an ion B in the presence of an aqueous silicate or polysilicate solution, whereby the ions A and B represent ions of a precipitable salt AB having a pK value of at least 4, measured at 20&deg; C. in water. The invention further relates to aqueous silicate or polysilicate solutions, their preparation and use as precursors for polysilicate microgels. The aqueous silicate or polysilicate solutions contain an ion A which is calcium or magnesium, wherein the molar ratio of SiO :A is less than 2000:1 and higher than 1:1, or an ion B which is carbonate, sulfate or phosphate, wherein the molar ratio of SiO :B is less than 2000:1 and higher than 1:1.

Polysilicate microgels and silica-based materials

The invention concerns a method of protecting a surface of a carbonatic material from corrosion, the method comprising treatment of the material surface with an acidic cationic silica sol, the pH of the sol preferably being from about 4 to about 7. The invention also concerns a new silica sol useful for performing the method and a method of preparing the new silica sol. Further, the invention concerns carbonatic material comprising a surface layer of silica, the surface of the silica particles comprising a polyvalent metal oxide/hydroxide.

Method of protecting a surface

A method of protecting a porous material sensitive to corrosion caused by pollutants in the atmosphere. The method comprises treating the surface of the material with an agent containing more than 90% by weight of silica sol. The agent contains substantially no solid particles with a diameter exceeding about 1 micron. Porous building materials comprising a layer of gelled silica sol present in the pores below the material surface are prepared by the method.

Aqueous suspensions of colloidal particles, preparation and use of the

The present invention concerns a particulate agent for chemical and/or physical treatment of a fluid, such as a gas containing NO.sub.x and SO.sub.x, contains at least two particle types of different activity, the particle weight and/or particle size of each type lying within separate ranges. The agent may also contain catalyst particles for reducing NO.sub.x, and particles for absorbing SO.sub.x. The invention also concerns a method and a plant for treating a fluid with the inventive particulate agent.

Process for the removal of NO.sub.x SO.sub.x utilizing a particulate

The invention relates to a catalyst for the reduction of nitrogen oxides and comprises oxides of transition metals on a particulate carrier material, the catalyst comprising:

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Kungalv, Sweden

Marek T Tokarz