Ube Material Industries, Ltd.

Tatsuki Okutsu

Ryoichi Nomura

Naoto Nishida

Akira Yoshida

Naoki Funabashi

To provide magnesium oxide which is excellent in hydration resistance and hardly causes volume expansion due to hydration and the like, a resin composition containing the same, and a method for producing the magnesium oxide powder. Magnesium oxide powder having a coating layer mainly comprising basic magnesium carbonate in the surface layer, when the amounts of substances of water vapor and carbon dioxide among the gas generated by thermal decomposition at 50 to 500&#xb0; C. are respectively designated as m-HO and m-CO, in a heating evolved gas analysis (EGA-MS) method, the molar fraction represented by m-CO/(m-HO+m-CO) being within the range of 0.3 to 0.6.

Magnesium oxide powder, resin composition including same, and method for producing magnesium oxide powder

A fibrous basic magnesium sulfate powder which does not contain COin an amount of more than 0.15% by mass, or a fibrous basic magnesium sulfate powder which has a ratio of the infrared absorption within the wave number range of 1,400-1,440 cmrelative to the infrared absorption within the wave number range of 3,180-3,530 cmof 0.005 or less. The fibrous basic magnesium sulfate powders exhibit improved physical property-improving effect when dispersed in a resin material.

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Ube, Japan

Tatsuki Okutsu