Akzo Nobel N.v.

Eka Chemicals Ab

Akzo Nobel Pulp and Performance Chemicals Ab

Maj-Lis Dahlgren

Michael Persson

Marek T Tokarz

Hans Erik Johansson-Vestin

Bozena Stanislawa Tokarz

Ylva Cruslock

Lars Lindahl

Hans Johansson

Marek Tokarz

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 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.

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 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.

Polysilicate microgels

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.

An aqueous dispersion comprising particles of a zeolite having a hydrophobicity of below about 9.0 percent by weight residual butanol as determined by the Residual Butanol Test, which dispersion comprises a stabilizing amount of biogum. Production of the dispersion comprising mixing zeolite particles with a biogum into a dry mixture; and mixing the dry mixture with water under agitation into a homogeneous mixture. Use of the dispersion for binding particles of zeolite to fibers. Production of paper or paperboard by forming and dewatering a suspension of cellulosic fibers wherein dewatering is carried out in the presence of particles of a zeolite, the dispersion being added to the suspension prior to dewatering. Production of dry-laid paper, nonwoven or fluff pulp, in which cellulosic fibers are carried by a gas stream, in which the dispersion is sprayed onto the fibers while they are carried by the gas stream.

Growing community of inventors

Nödinge, Sweden

Maj-Lis Dahlgren