Abstract: Magnesium hydroxide having low glossiness and acid resistance which is required for coatability. The magnesium hydroxide is coated magnesium hydroxide comprising magnesium hydroxide and colloidal silica coating the surface thereof, wherein (A) the coating amount of colloidal silica is 0.1 to 20.0 wt % in terms of SiO2 based on 100 wt % of magnesium hydroxide; and (B) the coated magnesium hydroxide has a long diameter (width) of 0.5 to 20 ?m, a thickness of 0.01 to 0.5 ?m and an aspect ratio of not less than 10.

Abstract: A resin composition which overcomes the defects of needle-like basic magnesium sulfate and has good balance among mechanical strength, molding productivity and the appearance of a molded article. The resin composition comprises (i) 100 parts by weight of a resin (component A), (ii) plate-like magnesium hydroxide having a crystal thickness (y) of 0.2 ?m or less, a crystal width (x) of 3.5 to 10 ?m and an aspect ratio of 20 to 100 (component B) and (iii) needle-like basic magnesium sulfate (component C), wherein the total content of the components B and C is 1 to 100 parts by weight based on 100 parts by weight of the resin, and the weight ratio of the component B to the component C is 0.1 to 0.9:0.9 to 0.1.

Abstract: A heat conductivity improving agent which can provide high heat conductivity to a resin. The heat conductivity improving agent comprises a magnesium hydroxide particle having a thickness of 10 nm to 0.2 ?m and an aspect ratio (long diameter/thickness) measured by a SEM method of not less than 10.

Abstract: A composite flame retardant which exhibits excellent flame retardancy and high dispersibility in a resin and rarely experiences the deterioration of mechanical strength, and a resin composition comprising the composite flame retardant. The composite flame retardant contains (i) 100 parts by weight of magnesium hydroxide particles (A) having an average thickness of 10 to 100 nm, an average width of 2.4 ?m or more and an average aspect ratio of 20 to 120 and (ii) 100 to 900 parts by weight of magnesium hydroxide particles (B) having an average width of 1 ?m or less and an average aspect ratio of less than 20.

Abstract: A resin composition which overcomes the defects of needle-like basic magnesium sulfate and has good balance among mechanical strength, molding productivity and the appearance of a molded article. The resin composition comprises (i) 100 parts by weight of a resin (component A), (ii) plate-like magnesium hydroxide having a crystal thickness (y) of 0.2 ?m or less and an aspect ratio of 20 to 100 (component B) and (iii) needle-like basic magnesium sulfate (component C), wherein the total content of the components B and C is 1 to 100 parts by weight based on 100 parts by weight of the resin, and the weight ratio of the component B to the component C is 0.1 to 0.9:0.9 to 0.1.