The invention relates to a novel process for preparing a precipitated silica, in which: a silicate is reacted with an acidifying agent, so as to obtain a suspension of precipitated silica, said suspension of precipitated silica is filtered, so as to obtain a filter cake, said filter cake is subjected to a liquefaction operation, after the liquefaction operation, a drying step is performed,
characterized in that at least one polycarboxylic acid is added to the filter cake, during or after the liquefaction operation.

The invention also relates to novel precipitated silicas and to uses thereof.

The invention relates to a process for the preparation of a modified silica comprising the step of adsorbing at least one polycarboxylic acid on precipitated silica.

This invention provides methods and technology related to increased hiding power of a coating through mediating the interaction of the pigment with other system components including but not limited to other pigment particles, latex paint particles, latex binding particles, and organic or inorganic hollow particles. Organization and spacing are tailored via pH sensitive functionalities hosted on ligands or polymeric spacers that are located at/within the surface of one of the components.

An object is to provide a novel method for producing spherical silica particles having fine voids. That is, spherical silica particles according to the present disclosure contain silica as a main component, have an average particle diameter of 0.1 to 10.0 m, a true specific gravity of 0.9 to 1.9 g/cm.sup.3, the true specific gravity being measured with nitrogen gas, a pore volume of 0.1 mL/g or lower, an Na content of 10 ppm or lower, and a true specific gravity retention rate of 80% or higher, the true specific gravity retention rate being measured with nitrogen gas and being a rate between before and after pressurization is performed at 300 MPa for 1 minute, and include, in an existence proportion of 60% or lower, particles in each of which a maximum value among major axes of internal voids is not smaller than half a major axis of the particle.

The present invention provides a light stabilizer composition having an improved blocking resistance, a method of producing a resin composition containing the same, a method of improving the blocking resistance of a light stabilizer composition, and a hindered amine compound for use in any of these. The light stabilizer composition according to the present invention contains a hindered amine compound and silica, wherein the hindered amine compound includes a compound represented by the following general formula (1), and the value of agglomerate hardness, as measured by a predetermined measurement method, is 55 N or less. (In the general formula (1), R.sup.1 represents a hydrogen atom or the like; and R.sup.2 represents an alkyl group or the like.)

Methods and compositions utilize a sand obtained by combining a dirty sand with a chemical additive, where the combination decreases the water drain time through the sand compared to the sand without the chemical additive. The decrease of water drain time reduces the amount of time to dry the sand after a wash, and when using the sand for proppant, promotes conductivity of fluid through the sand when the sand is in a fracture of a subterranean formation.

A method for coating a surface of fused silica material is provided. A surface of a piece of material is pre-conditioned with a hydrolyzing reagent creating an SiOH or ROH bond on the surface. The surface is covered with thionyl chloride for a predetermined amount of time converting the SiOH bond on the surface to an SiCl. The thionyl chloride is removed and the surface is covered with a compound or mixture having an amine group converting the SiCl bond to an SiNR bond. The compound or mixture is removed.

A fire retardant material includes a deconstructed nanoporous material including a plurality of elements, and solids of a fire-retarding solution within the elements of the nanoporous material. A method of forming the fire retardant material includes combining a nanoporous material and a fire-retarding solution such that elements of the nanoporous material absorb the fire retarding solution, and evaporating liquid from the elements of the nanoporous material having the fire-retarding solution absorbed therein such that a concentrate or solids thereof remain within the elements of the nanoporous material.

An object is to provide a novel method for producing spherical silica particles having fine voids. That is, spherical silica particles according to the present disclosure contain silica as a main component, have an average particle diameter of 0.1 to 10.0 m, a true specific gravity of 0.9 to 1.9 g/cm.sup.3, the true specific gravity being measured with nitrogen gas, a pore volume of 0.1 mL/g or lower, an Na content of 10 ppm or lower, and a true specific gravity retention rate of 80% or higher, the true specific gravity retention rate being measured with nitrogen gas and being a rate between before and after pressurization is performed at 300 MPa for 1 minute, and include, in an existence proportion of 60% or lower, particles in each of which a maximum value among major axes of internal voids is not smaller than half a major axis of the particle.

A biocompatible hydrogel hybrid material useful in regenerative medicine, in particular in reconstruction of bone tissue and a method of its preparation is disclosed.