| abstract |
A magnesium oxide having excellent hydration resistance and hardly causing volume expansion due to hydration, a resin composition containing the magnesium oxide, and a method for producing a magnesium oxide powder are provided. A magnesium oxide powder having a coating layer mainly composed of basic magnesium carbonate as a surface layer, and generated by thermal decomposition at 50 to 500 ° C. in a heat generation gas analysis (EGA-MS) method. of water vapor and carbon dioxide substance amount m-H 2 O, respectively, when the m-CO 2, m-CO 2 / (m-H 2 O + m-CO 2) in a mole fraction represented by 0 . Magnesium oxide powder characterized by being in the range of 3 to 0.6. [Selection] Figure 1 |