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.

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.

A tunable one-pot method for producing nanoparticles for plant defense and growth enhancement that include components that collectively exhibit multiple release profiles of active ingredients when exposed to release conditions, such as contact with water, or sufficient moisture, or changes in pH, or the presence of plant roots. In a preferred embodiment, the method produces round or substantially round amorphous hydroxylated (and thus water soluble and low toxicity) nanoparticles having i) a silica-based core that exhibits a slow release rate and ii) silica mono- and/or oligomer based nanodomains and/or one or more active ingredients associated with the core, entrapped in nanopores or nanodomains, and/or adsorbed to the surface, etc., that exhibit at least a second, faster release rate under release conditions, wherein the active ingredient includes one or more of a silica monomer and/or oligomer and/or additional active ingredients such as a pesticide, nutrient, prebiotic, or phytostimulant Methods for producing nanoparticles for agricultural use are disclosed, including colloidal synthesis steps that provide precise, tunable control of the architecture of the nanoparticles. Advantageously, the nanoparticles resulting from this process are suitable for use as plant growth and defense enhancers through delivery of the silica mono- and/or oligomers and/or active ingredients, by hormesis/plant nanopriming, or by mixture with conventional agrochemicals.

A tunable one-pot method for producing nanoparticles for plant defense and growth enhancement that include components that collectively exhibit multiple release profiles of active ingredients when exposed to release conditions, such as contact with water, or sufficient moisture, or changes in pH, or the presence of plant roots. In a preferred embodiment, the method produces round or substantially round amorphous hydroxylated (and thus water soluble and low toxicity) nanoparticles having i) a silica-based core that exhibits a slow release rate and ii) silica mono- and/or oligomer based nanodomains and/or one or more active ingredients associated with the core, entrapped in nanopores or nanodomains, and/or adsorbed to the surface, etc., that exhibit at least a second, faster release rate under release conditions, wherein the active ingredient includes one or more of a silica monomer and/or oligomer and/or additional active ingredients such as a pesticide, nutrient, prebiotic, or phytostimulant Methods for producing nanoparticles for agricultural use are disclosed, including colloidal synthesis steps that provide precise, tunable control of the architecture of the nanoparticles. Advantageously, the nanoparticles resulting from this process are suitable for use as plant growth and defense enhancers through delivery of the silica mono- and/or oligomers and/or active ingredients, by hormesis/plant nanopriming, or by mixture with conventional agrochemicals.

The present invention provides colloidal silica that exhibits excellent abrasiveness and contains, with high purity, deformed silica particles with excellent compactness and a large amount of alkoxy groups per unit area; the invention also provides a method for producing the colloidal silica in a simple manner with reduced costs. The invention provides colloidal silica containing silica particles having a bent structure and/or a branched structure, wherein the silica particles have a particle density of 1.95 or more, the silica particles have a ratio (m/n) of the content of alkoxy groups m (ppa) to the average primary particle size n (nm) of 200 or more, and the silica particles having a bent structure and/or a branched structure are present in an amount of 15% or more based on the number of particles in a given field of view as observed with a scanning electron microscope at 200,000-times magnification.

The present invention provides colloidal silica that exhibits excellent abrasiveness and contains, with high purity, deformed silica particles with excellent compactness and a large amount of alkoxy groups per unit area; the invention also provides a method for producing the colloidal silica in a simple manner with reduced costs. The invention provides colloidal silica containing silica particles having a bent structure and/or a branched structure, wherein the silica particles have a particle density of 1.95 or more, the silica particles have a ratio (m/n) of the content of alkoxy groups m (ppa) to the average primary particle size n (nm) of 200 or more, and the silica particles having a bent structure and/or a branched structure are present in an amount of 15% or more based on the number of particles in a given field of view as observed with a scanning electron microscope at 200,000-times magnification.

A lost circulation material (LCM) is provided having an alkaline nanosilica dispersion and an ester activator. The alkaline nanosilica dispersion and the ester activator may form a gelled solid after interaction over a contact period. Methods of lost circulation control using the LCM are also provided.

The present invention provides colloidal silica containing silica particles excellent in compactness and excellent in maintenance of the bumpy surface under basic conditions, and provides a method for producing the colloidal silica. The present invention provides colloidal silica containing silica particles having a bumpy surface, wherein (1) the silica particles have a content of alkoxy groups of 1000 ppm or more, and (2) the silica particles have a reduction in specific surface area of 15.0% or less when the silica particles are heated under basic conditions.

Colloidal silica containing silica particles that have a small particle size (e.g., an average primary particle size of 20 nm or less) and that contain alkoxy groups, and a method for producing the colloidal silica, are disclosed. The colloidal silica containing silica particles can have a small particle size and exhibit a suppressed increase in the average secondary particle size after storage. The colloidal silica containing silica particles wherein the silica particles have an average primary particle size of 20 nm or less, the silica particles have a ratio (m/n) of the content of alkoxy groups m (ppm) to the average primary particle size n (nm) of 300 or more, the silica particles have a particle density of 1.95 or more, and the silica particles have an increase rate of average secondary particle size of 12% or less in a storage stability test.

Colloidal silica containing silica particles that have a small particle size (e.g., an average primary particle size of 20 nm or less) and that contain alkoxy groups, and a method for producing the colloidal silica, are disclosed. The colloidal silica containing silica particles can have a small particle size and exhibit a suppressed increase in the average secondary particle size after storage. The colloidal silica containing silica particles wherein the silica particles have an average primary particle size of 20 nm or less, the silica particles have a ratio (m/n) of the content of alkoxy groups m (ppm) to the average primary particle size n (nm) of 300 or more, the silica particles have a particle density of 1.95 or more, and the silica particles have an increase rate of average secondary particle size of 12% or less in a storage stability test.