Abstract: The present invention relates to a method of treating an aqueous suspension of bleached pulp derived from an alkaline pulping process comprising dewatering and drying said suspension, wherein the pH of the suspension to be treated ranges from about 6.5 to about 12.

Abstract: The present invention concerns a process for the production of a cellulosic product comprising providing a fiber-containing suspension, wherein at least about 60% by weight of the fibers are cellulosic fibers, and dewatering the suspension on a wire to form a cellulosic fiber web, the process further comprising adding silica-based particles to the formed web and a wet strength agent to the suspension and/or to the formed web. The invention also concerns a product obtainable by the process. The invention further concerns a dispersion comprising silica-based particles and a substantially aldehyde-free wet strength agent. A further aspect of the invention concerns a dispersion comprising silica-based particles having a specific surface area ranging from about 1000 to about 1700 m2/g and a wet strength agent. Still another aspect of the invention concerns the use of the dispersion as an additive in a papermaking process.

Abstract: A process for the production of an aqueous sol containing silica-based particles which comprises (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 SiO2 content within the range of from 4.5 to 8% by weight; (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° C.; (d) alkalising the obtained sol to a pH of at least 10.0; and (e) optionally concentrating the sol obtained according to (b), (c) or (d) to provide an aqueous sol containing silica-based particles and having a specific surface area of at least 90 m2/g aqueous sol; as well as an aqueous sol containing silica-based particles obtainable by the process.

Abstract: The invention relates to an aqueous sol containing silica-based particles which sol has a specific surface area of at least 115 m2/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 m2/g and less than 1000 m2/g SiO2. 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.

Abstract: The invention relates to an aqueous dispersion of cellulose-reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or quaternary ammonium thereof having a molecular weight less than 180 and/or having one or more hydroxyl groups. The invention further relates to a process for the production of paper which comprises adding the aqueous dispersion of cellulose-reactive sizing agent to an aqueous cellulosic suspension.

Abstract: The present invention concerns a process for the production of a cellulosic product comprising providing a fiber-containing suspension, wherein at least about 60% by weight of the fibers are cellulosic fibers, and dewatering the suspension on a wire to form a cellulosic fiber web, the process further comprising adding silica-based particles to the formed web and a wet strength agent to the suspension and/or to the formed web. The invention also concerns a product obtainable by the process. The invention further concerns a dispersion comprising silica-based particles and a substantially aldehyde-free wet strength agent. A further aspect of the invention concerns a dispersion comprising silica-based particles having a specific surface area ranging from about 1000 to about 1700 m2/g and a wet strength agent. Still another aspect of the invention concerns the use of the dispersion as an additive in a papermaking process.

Abstract: The present invention generally relates to polysilicate microgels. More specifically, the invention relates to a process for preparing aqueous polysilicate microgels which comprises mixing an aqueous solution of alkali metal silicate with an aqueous phase of silica-based material having a pH of 11 or less, to polysilicate microgels per se and to the use thereof as flocculating agents in paper making and water purification. The invention further relates to a process for the production of paper from a suspension of cellulosic fibers, and optional filler, which comprises adding to the suspension at least one cationic or amphoteric organic polymer and a polysilicate microgel, forming and draining the suspension on a wire.

Abstract: The present invention refers to a process for the production of paper from a suspension containing cellulosic fibers, and optionally fillers, comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles in an amount of at least 0.01% by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent. The invention also encompasses an aqueous silica-containing composition and a method for preparation of an aqueous silica-containing compound.

Abstract: The present invention relates to a method of treating an aqueous suspension of bleached pulp derived from an alkaline pulping process comprising dewatering and drying said suspension, wherein the pH of the suspension to be treated ranges from about 6.5 to about 12.

Abstract: The invention relates to an aqueous dispersion of cellulose-reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or quaternary ammonium thereof having a molecular weight less than 180 and/or having one or more hydroxyl groups. The invention further relates to a process for the production of paper which comprises adding the aqueous dispersion of cellulose-reactive sizing agent to an aqueous cellulosic suspension.

Abstract: The present invention refers to a process for the production of paper from a suspension containing cellulosic fibers, and optionally fillers, comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles in an amount of at least 0.01% by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent. The invention also encompasses an aqueous silica-containing composition and a method for preparation of an aqueous silica-containing compound.

Abstract: The invention related to process for the production of paper from an aqueous suspension containing cellulosic fibers, and optional fillers, which comprises adding to the suspension (i) a cationic vinyl addition polymer prepared by polymerizing one or more ethylenically unsaturated monomers comprising a cationic monomer; (ii) an anionic polymer having one or more aromatic groups selected from the group consisting of polymers obtained by condensation of formaldehyde with benzene-based and naphthalene-based compounds, polyurethanes, polysaccharides, and lignin-based polymers; wherein (i) and (ii) are separately added to the suspension; and (iii) a low molecular weight cationic organic polymer having a molecular weight in the range of from 2,000 to about 700,000; or an anionic microparticulate material; and forming and draining the obtained suspension on a wire.

Abstract: The present invention refers to a process for the production of paper from a suspension containing cellulosic fibres, and optionally fillers, comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles in an amount of at least 0.01% by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent. The invention also encompasses an aqueous silica-containing composition and a method for preparation of an aqueous silica-containing compound.

Abstract: A process for the production of an aqueous sol containing silica-based particles which comprises (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 SiO2 content within the range of from 4.5 to 8% by weight; (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° C.; (d) alkalising the obtained sol to a pH of at least 10.0; and (e) optionally concentrating the sol obtained according to (b), (c) or (d) to provide an aqueous sol containing silica-based particles and having a specific surface area of at least 90 m2/g aqueous sol; as well as an aqueous sol containing silica-based particles obtainable by the process.

Abstract: The present invention relates to an aqueous silica-containing composition comprising an anionic organic polymer having at least one aromatic group and anionic silica-based particles. The aqueous silica-containing composition contains the anionic organic polymer having at least one aromatic group and the anionic silica-based particles in an amount of at least 0.01% by weight of the total weight of the aqueous silica-containing composition. The aqueous silica-containing composition contains substantially no cellulose-reactive sizing agent and the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulphonate formaldehyde condensate. The invention further relates to methods for the preparation of the aqueous silica-containing composition and the use of the aqueous silica-composition as a drainage and retention aid in a process for the production of paper.

Abstract: The present invention refers to a process for the production of paper from a suspension containing cellulosic fibers, and optionally fillers, comprising adding to the suspension at least one cationic organic polymer and an aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and anionic silica-based particles, the composition having a weight ratio of naphthalene sulphonate formaldehyde condensate to silica-based particles within the range of from 0.2:1 to 99:1, and containing naphthalene sulphonate formaldehyde condensate and silica-based particles in an amount of at least 0.01% by weight, based on the total weight of the aqueous silica-containing composition, and with the proviso that the composition contains substantially no cellulose-reactive sizing agent. The invention also encompasses an aqueous silica-containing composition and a method for preparation of an aqueous silica-containing compound.

Abstract: The present invention relates to an aqueous silica-containing composition comprising an anionic organic polymer having at least one aromatic group and anionic aggregated or microgel formed silica-based particles. The aqueous silica-containing composition contains the anionic organic polymer having at least one aromatic group and the anionic silica-based particles in an amount of at least 0.01% by weight of the total weight of the aqueous silica-containing composition. The aqueous silica-containing composition contains substantially no cellulose-reactive sizing agent and the anionic organic polymer having at least one aromatic group is not an anionic naphthalene sulphonate formaldehyde condensate.

Abstract: The present invention generally relates to polysilicate microgels. More specifically, the invention relates to a process for preparing aqueous polysilicate microgels which comprises mixing an aqueous solution of alkali metal silicate with an aqueous phase of silica-based material having a pH of 11 or less, to polysilicate microgels per se and to the use thereof as flocculating agents in paper making and water purification. The invention further relates to a process for the production of paper from a suspension of cellulosic fibers, and optional filler, which comprises adding to the suspension at least one cationic or amphoteric organic polymer and a polysilicate microgel, forming and draining the suspension on a wire.

Abstract: The invention relates to a process for manufacturing paper and board comprising providing a suspension comprising cellulosic fibres and at least a sizing agent, dewatering said suspension thereby forming a paper-web, whereby an aromatic-containing cationic vinyl addition polymer, and an anionic polymer having a weight average molecular weight of up to about 500,000 selected from the group consisting of vinyl addition polymers and condensation polymers is added separately to the suspension.

Abstract: A process for the production of an aqueous sol containing silica-based particles which comprises (a) acidifying an aqueous silicate solution to a pH of from 1 to 4 to form an acid sol; (b) alkalizing the acid sol at an SiO2 content within the range of from 4.5 to 8% by weight; (c) allowing particle growth of the alkalized sol for at least 10 minutes; or heat-treating the alkalized sol at a temperature of a least 30° C.; (d) alkalizing the obtained sol to a pH of at least 10.0; and (e) optionally concentrating the sol obtained according to (b), (c) or (d) to provide an aqueous sol containing silica-based particles and having a specific surface area of at least 90 m2/g aqueous sol; as well as an aqueous sol containing silica-based particles obtainable by the process.