Halogen free flame retardant thermoplastic elastomer compositions having improved insulation resistance

Abstract

Halogen-free flame retardant compositions comprising coplyetherester thermoplastic elastomers, melamine cyanurate and epoxy-containing compounds and cables and wires made from such flame retardant polymer composition provide good electrical insulation resistance during use.

What is claimed is: 
     
         1 . A flame retardant polymer composition comprising:
 a) one or more copolyetherester thermoplastic elastomers;   b) melamine cyanurate; in an amount of between 10 to 30 weight percentage, based on the total weight of the flame retardant polymer composition and   c) at least one epoxy-containing compound.   
     
     
         2 . The flame retardant polymer of  claim 1 , further comprising at least one compound selected from the group consisting of phosphites and aromatic phosphate ester flame retardants and mixtures thereof; with the proviso that i) when the flame retardant polymer composition comprises an aromatic phosphate ester flame retardant and a phosphite, the amount of epoxy-containing compound present is such that the total epoxy functional group equivalent weight is at least about 32 milliequivalents per kg of the combined weight of the one or more copolyetherester thermoplastic elastomers and the aromatic phosphate ester flame retardant and ii) when the flame retardant polymer composition comprises an aromatic phosphate ester flame retardant in the absence of phosphite, the amount of epoxy-containing compound present is such that the total epoxy functional group equivalent weight is at least about 56 milliequivalents per kg of the combined weight of the one or more copolyetherester thermoplastic elastomers and the aromatic phosphate ester flame retardant. 
     
     
         3 . A flame retardant polymer composition according to  claim 1 , wherein the one or more copolyetherester thermoplastic elastomers are copolyetherester elastomers having a multiplicity of recurring long-chain ester units and short-chain ester units joined head-to-tail through ester linkages, said long-chain ester units being represented by formula (A): 
       
         
           
           
               
               
           
         
         and said short-chain ester units being represented by formula (B): 
       
       
         
           
           
               
               
           
         
         wherein: 
         G is a divalent radical remaining after the removal of terminal hydroxyl groups from poly(alkylene oxide)glycols having a number average molecular weight of between about 400 and about 6000; 
         R is a divalent radical remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight of less than about 300; and 
         D is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about 250. 
       
     
     
         4 . A flame retardant polymer composition according to  claim 1 , wherein the one or more copolyetherester thermoplastic elastomers are copolyetherester elastomers prepared from monomers comprising (1) poly(tetramethylene oxide) glycol or poly(trimethylene oxide) glycol and mixtures thereof; (2) a dicarboxylic acid selected from the group consisting of isophthalic acid, terephthalic acid and mixtures thereof; and (3) a diol selected from the group consisting of 1,4-butanediol, 1,3-propanediol and mixtures thereof. 
     
     
         5 . A flame retardant polymer composition according to  claim 1  wherein the at least one copolyetherester thermoplastic elastomers are copolyetherester elastomers prepared from monomers comprising (1) poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected from the group consisting of terephthalic acid; and (3) a diol selected from the group consisting of 1,4-butanediol, 1,3-propanediol and mixtures thereof and wherein the level of poly(tetramethylene oxide) glycol is less than about 25 weight percent based on the total weight of the copolyetherester elastomers. 
     
     
         6 . A flame retardant polymer composition according to  claim 5 , further comprising at least one copolyetherester thermoplastic elastomer prepared from monomers comprising (1) poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected from the group consisting of mixtures of isophthalic acid and terephthalic acid; and (3) a diol selected from the group consisting of 1,4-butanediol, 1,3-propanediol and mixtures thereof and wherein the level of said copolyetherester elastomer is from about 5 to about 50 weight percent based on the total weight of the copolyetherester elastomers. 
     
     
         7 . A flame retardant polymer composition according to  claim 1  wherein the amount of epoxy-containing compound c) is such that it provides from at or about 2.4 to about 10 milliequivalents of total epoxy functionality based on hundred grams of the total weight of the flame retardant polymer composition. 
     
     
         8 . A flame retardant polymer composition according to  claim 1  wherein the amount of phosphite is from at or about 0.1 to 1 weight percent based on the total weight of the flame retardant polymer composition. 
     
     
         9 . A flame retardant polymer composition according to  claim 1  wherein the amount of aromatic phosphate ester is from at or about 2 to 12 weight percent based on the total weight of the flame retardant polymer composition. 
     
     
         10 . A flame retardant polymer composition according to  claim 1  wherein the epoxy-containing compound c) is selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane-epichlorohydrin copolymer and tetraglycidyl ether of tetraphenol ethane and combinations thereof. 
     
     
         11 . A flame retardant polymer composition according to  claim 1  wherein the phosphite is a pentaerythritol diphosphite. 
     
     
         12 . A flame retardant polymer composition according to  claim 1  wherein the aromatic phosphate ester is selected from the group consisting of resorcinol bis(di-2,6-dimethylphenyl phosphate) and bisphenol bis(di-2,6-dimethylphenyl phosphate) and combinations thereof. 
     
     
         13 . A wire or cable comprising a coating made of the flame retardant polymer composition recited in  claim 1 .