Flame-retardant composition and insulated wire, and method for producing flame-retardant composition

A flame-retardant composition comprising:

• a polymer component comprising:
• silane-crosslinked polyolefin;
• and
• polyolefin, the polyolefin content being 32 to 157 parts by mass with respect to 100 parts by mass of the silane-crosslinked polyolefin;
• at least one of magnesium hydroxide and aluminum hydroxide, the content of the at least one of magnesium hydroxide and aluminum hydroxide being 28 to 190 parts by mass with respect to 100 parts by mass of the polymer component;
• a phenolic antioxidant, the phenolic antioxidant content being 0.5 to 9.5 parts by mass with respect to 100 parts by mass of the polymer component;
• a sulfurous antioxidant that comprises a benzimidazole compound, the sulfurous antioxidant content being 5 to 9.5 parts by mass with respect to 100 parts by mass of the polymer component;
• a zinc oxide, the zinc oxide content being 0.5 to 9.5 parts by mass with respect to 100 parts by mass of the polymer component;
• and
• a copper inhibitor, the copper inhibitor content being 0.1 to 4.7 parts by mass with respect to 100 parts by mass of the polymer component,
• wherein:
• the silane-crosslinked polyolefin comprises polyethylene having a density of 0.880 to 0.910 g/cm3 that is silane-crosslinked, and
• the polyolefin consists of:
• a polypropylene elastomer having a melting point of 140° C. or more;
• and
• a polyethylene that is the same as the polyethylene from which the silane-crosslinked polyolefin is made.