A method for producing forsterite microparticles having a primary particle size of 1, to 50 nm, as determined through electron microscopy. The method includes spray-drying, in an atmosphere of 50° C. or higher and lower than 300° C., a solution containing a water-soluble magnesium salt and colloidal silica at a mole ratio of magnesium atoms to silicon atoms (Mg/Si) of 2; and subsequently, firing the spray-dried product in air at 800 to 1,000° C.

A filler composition is excellent in heat dissipation. A silicone resin composition includes the filler composition. A heat dissipation element is made by molding the silicone resin composition. More specifically, the filler composition has a filler (A1) having an average particle diameter of 0.3-1.0 μm, a filler (A2) having an average particle diameter of 3-15 μm, and a filler (A3) having an average particle diameter of 35-140 μm, wherein the filler (A1), the filler (A2) and the filler (A3) are one or more kinds selected from alumina, magnesia, AlN covered alumina, AlN and SN.

The present invention discloses magnesia and a method for manufacturing same, wherein the magnesia can be produced into granules of various shapes and sizes and can be improved in moisture resistance with the formation of a moisture resistant surface oxide layer by donor addition and then thermal treatment. The magnesia according to the present invention comprises a MgO granule; and a surface oxide layer formed on a surface of the MgO granule and a composition of the surface oxide layer is different from a composition of an inside of the MgO granule.

Coated magnesium oxide particles having high filling efficiency and high mass-productivity and suitable for a thermal conductive filler are provided, the coated magnesium oxide particles being coated magnesium oxide particles in which the surface of magnesium oxide particles is coated with at least one of a fatty acid and a fatty acid metal salt, and wherein X in relation to particles is defined as X=[a BET specific surface area diameter calculated from a BET specific surface area of the particles]÷[D.sub.50 of the particles], provided that D.sub.50 is a particle diameter at 50% accumulation in a cumulative particle size distribution of the particles, the magnesium oxide particles having X of less than 0.2 and D.sub.50 of 5 to 100 μm, and the coated magnesium oxide particles having X of 0.2 or more, D.sub.50 of 5 to 100 μm, and oil absorption of less than 25 mL/100 g.

Provided is a filler that has a low viscosity when mixed in a resin material and has reduced permittivity and dielectric loss tangent. The filler includes: a metal oxide particle material; and a polyorganosiloxane compound with which a surface treatment is performed on the metal oxide particle material and which is represented by general formula (1): (RO).sub.3Si—(SiR.sub.2—O—).sub.n—SiR.sub.3 (in general formula (1), each R is independently selected from among alkyl groups having 1 to 4 carbon atoms, and n is not less than 10 and not greater than 200). A resin composition obtained by containing the filler in a resin is suitable for an electronic material.

Inorganic particulate compositions containing inorganic particles associated with a copolymer of a hydrophilic monomer and a hydrophobic monomer associated with the inorganic particles are provided. The particulate composition satisfies at least one of the following properties: a BET surface area of the inorganic particles is greater than 8 m.sup.2/g, a Hegman value of the inorganic particles is 75 microns or less, and a rate of water loss from the composition upon drying from a moisture level greater than 2% wt % is at least 30% greater than a composition having a corresponding content of a polyacrylate polymer associated with the particles. A method to prepare the composition and formulations for inks, paints, coatings and filled polymeric articles containing the inorganic particulate composition are also provided.

The present invention refers to a process for the preparation of a surface-treated magnesium hydroxide-comprising material, a surface-treated magnesium hydroxide-comprising material as well as the use of the surface-treated magnesium hydroxide-comprising material in polymer composition, in paper making, paper coatings, agricultural applications, paints, adhesives, sealants, composite materials, wood composite materials, construction applications, pharma applications and/or cosmetic applications as well as surrounding materials, wherein the surface treatment agent of the surface-treated magnesium hydroxide-comprising material is undergoing a reaction with the surrounding material.

A basic magnesium sulfate powder according to the present invention has a surface at least partially coated with an inorganic phosphorus compound. The basic magnesium sulfate powder preferably has a phosphorus content of from 0.001 to 5.0 mass %.

Inorganic particulate compositions containing inorganic particles associated with a copolymer of a hydrophilic monomer and a hydrophobic monomer associated with the inorganic particles are provided. The particulate composition satisfies at least one of the following properties: a BET surface area of the inorganic particles is greater than 8 m.sup.2/g, a Hegman value of the inorganic particles is 75 microns or less, and a rate of water loss from the composition upon drying from a moisture level greater than 2% wt % is at least 30% greater than a composition having a corresponding content of a polyacrylate polymer associated with the particles. A method to prepare the composition and formulations for inks, paints, coatings and filled polymeric articles containing the inorganic particulate composition are also provided.

A basic magnesium sulfate powder according to the present invention has a surface at least partially coated with an inorganic phosphorus compound. The basic magnesium sulfate powder preferably has a phosphorus content of from 0.001 to 5.0 mass %.