Abstract: Antimony pentoxide-containing flame retardant for halogen-containing vinyl resins which comprises, with respect to 100 parts by weight of Sb.sub.2 O.sub.5, (A) 3 to 20 parts by weight of an alkali metal in terms of M.sub.2 O wherein M represents an alkali metal, (B) 1 to 25 parts by weight of an alkaline earth metal in terms of M'O wherein M' represents an alkaline earth metal, and (C) 0.04 to 3 parts by weight of a compound selected from the group consisting of phosphoric acid, an ammonium salt of phosphoric acid, and an alkali metal salt of phosphoric acid, in terms of P.sub.2 O.sub.5, as well as a method for preparing the same.The flame retardant according to this invention does not impair, the transparency, the thermal stability, or the bleeding resistance of the halogen-containing vinyl resins.

Abstract: A flame retarded resin composition, which comprises 100 parts by weight of a synthetic resin, a sodium antimony phosphate amorphous product mixed in an amount of 0.05 to 30 parts by weight based on said synthetic resin, and optionally a flame retardant such as an organic halogenated compound further mixed in an amount of 1 to 30 parts by weight based on said synthetic resin. The resin composition has good transparency and coloring property.