Flame retardant thermoplastic multi-block copolyester elastomers

Claim 1

A substantially nondripping flame retardant copolyester elastomer composition which comprises (a) a multi-block copolyester elastomer consisting essentially of (A) repeating high melting point blocks comprising repeating short chain ester units having the formula ##STR5## wherein D is a divalent radical remaining after the removel of hydroxyl groups from a low molecular weight diol having a molecular weight not greater than 250 and R is a divalent radical remaining after the removal of carboxyl groups from a dicarboxylic acid having a molecular weight not greater than 300, D and R being selected so that a polymer consisting essentially of short chain ester units having a number average molecular weight of at least 5000 and has a melting point of at least 150° C., (B) repeating low melting point blocks which are derived from compounds containing hydroxyl groups or carboxyl groups or mixtures thereof and having a number average molecular weight of 400-4000 and a melting point not greater than about 100° C., and (C) an amount of difunctional radicals sufficient to join repeating blocks (A) and (B) to form a multi-block copolyester elastomer, the weight ratio of (A) to (B) being from about 1:0.67 to 1:2, (b) about 20-35 parts per 100 parts of said multi-block copolyester elastomer of a bromine-containing flame retardant containing at least 65% by weight bromine and having a weight loss of not greater than 5% at 250° C. as determined by thermogravimetric analysis in air at a heating rate of 10° C./minute, (c) about 0.20-0.75 parts per part of said bromine-coating flame retardant of antimony trioxide, and (d) about 2-10 parts per 100 parts of said multi-block copolyester elastomer of an organophilic clay which is the reaction product of at least one quaternary ammonium salt with a smectite clay having an ion exchange capacity of at least 75 meg/100 g of clay, said quaternary ammonium salt having the formula ##STR6## wherein M - is selected from the group consisting of chloride, bromide, iodide, nitrite, hydroxide, acetate, methyl sulfate and mixtures thereof, wherein R 1 is an alkyl group having 12-22 carbon atoms and wherein R 2 , R 3 and R 4 are selected from the group consisting of hydrogen, alkyl groups containing 1-22 carbon atoms, aryl groups and aralkyl groups containing 1-22 carbon atoms in the alkyl chain.