Spherical magnesium oxide, method for producing same, heat-conductive filler, and resin composition
AssigneeTateho Chemical Industries Co., Ltd.
InventorsYoshihisa OSAKI, Tomoaki CHIKAZAWA, Keisuke TSUTSUMI
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Abstract
The purpose of the present invention is to provide: spherical magnesium oxide having high sphericity, exceptional moisture resistance, and exceptional fluidity in a resin composition when a resin is filled therewith. The present invention is a spherical magnesium oxide characterized by containing 300-2000 ppm of boron, by the content of lithium being less than 15 ppm, and by the sphericity read from an SEM photograph in a volume-based cumulative 50% particle diameter (D50) range of 3-200 μm by laser diffraction scattering particle size distribution measurement being 1.00-1.20.
Claims4
A method for producing a spherical magnesium oxide, comprising the steps of:
- 1) reacting an aqueous magnesium chloride solution with an aqueous alkaline solution to prepare a magnesium hydroxide slurry,
- 2) drying and then firing the magnesium hydroxide slurry to prepare magnesium oxide particles,
- 3) forming a dispersion of the magnesium oxide particles and wet-grinding the magnesium oxide particles,
- 4) spray-drying the wet-ground magnesium oxide, and
- 5) firing the magnesium oxide granulated by the above step,
- wherein, in at least one of the steps 1) to 4), an amount of boron is adjusted so that a content of boron after the firing is 300 to 2,000 ppm and wherein, in at least one of the steps 1) to 2), a mixed lithium amount is reduced by a repulp washing, with a washing procedure repeated five or more times, so that a content of lithium in the produced spherical magnesium oxide is less than 1 ppm.
Dependencies are inferred from the claim text.