Fire retardant thermoplastic polyester type block copolymer composition

A fire retardant thermoplastic polyester block copolymer composition, which comprises (a) a thermoplastic polyester block copolymer consisting of a hard polyester segment having a high melting point and a soft polymer segment having a low melting point and a molecular weight of 400 to 6,000, wherein the hard polyester segment has a melting point of 150.degree.C or more when a high molecular weight polymer is produced from the component thereof alone, and the soft polymer segment has a melting point or softening point of 80.degree.C or less and is included in a ratio of 1 to 85% by weight, and (b) a mixture of one or more kinds of halogenated bisphenyl compounds selected from the group consisting of a compound of the formula (I), and a compound of the formula (II) and an organic or inorganic antimony compound in a ratio of 1:0 to 1:3 by weight:

• ##SPC5##
• wherein R.sub.1 and R.sub.2 are each hydrogen or an alkyl having 1 to 4 carbon atoms:
• R.sub.3 and R.sub.4 are each an alkyl having 1 to 18 carbon atoms;
• an acyl or glycidyl wherein the hydrogen combined with carbon atoms may be substituted by bromine or chlorine;
• A.sub.1, A.sub.2, are each oxygen or sulfur;
• B is oxygen, sulfur or sulfoxide;
• X.sub.1, X.sub.2, X.sub.3, X.sub.4, are each bromine or chlorine;
• m and n are an integer of 1 to 4 and m + n is 4 to 8;
• and p and q are an integer of 1 to 5 and p + q is 4 to 10.