Flame retardant polyester compositions

Abstract

A halogen-free, flame retardant polyester composition comprises, based on the total composition, (a) A poly(ethylene terephthalate) with a molecular weight of at least 50,000 or a blend of poly(ethylene terephthalate) with another polyester, taking into account that the ratio poly(ethylene terephthalate)/other polyester should be at least 55/45. (b) A combination of at least one N-containing compound, selected from the group of triazine, guanidine, or (iso)cyanurate compounds, and at least one P-containing compound, selected from the group of BPA-diphosphates or phosphoramides with the proviso that the ratio of the total amount of P- and N-containing compounds over the total polyester amount should be between 0.3 and 0.6 and the ratio of the P-containing compound over the N-containing compound should be higher than 0.8. (c) An anti-dripping agent in an amount of 0.01-2 weight percent of the total composition. (d) A reinforcing filler in an amount of 040 weight percent of the total composition.

What is claimed is:  
     
         1 . A halogen-free, flame retardant polyester composition comprises, based on the total composition, 
 (a) A poly(ethylene terephthalate) with a molecular weight of at least 50,000 or a blend of poly(ethylene terephthalate) with another polyester, taking into account that the ratio poly(ethylene terephthalate)/other polyester should be at least 55/45,    (b) A combination of at least one N-containing compound, selected from the group of triazine, guanidine, or (iso)cyanurate compounds, and at least one P-containing compound, selected from the group of BPA-diphosphates or phosphoramides with the proviso that the ratio of the total amount of P- and N-containing compounds over the total polyester amount should be between 0.3 and 0.6 and the ratio of the P-containing compound over the N-containing compound should be higher than 0.8,    (c) An anti-dripping agent in an amount of 0.01-2 weight percent of the total composition,    (d) A reinforcing filler in an amount of 0-40 weight percent of the total composition.    
     
     
         2 . The composition of  claim 1 , further comprising up to about 40 weight percent of glass fiber.  
     
     
         3 . The composition of  claim 1 , wherein the other polyester resin is derived from an aliphatic or cycloaliphatic diol, or mixtures thereof, containing from 3 to about 10 carbon atoms and at least one aromatic dicarboxylic acid.  
     
     
         4 . The composition of  claim 1 , wherein the other polyester has repeating units of the following general formula:  
       
         
           
           
               
               
           
         
       
       wherein n is an integer of from 3 to 6, and R is a C6-C20 aryl radical comprising a decarboxylated residue derived from an aromatic dicarboxylic acid.  
     
     
         5 . The composition of  claim 1 , wherein the ratio of the total amount of P- and N-containing compounds over the polyester is between 0.35 and 0.58.  
     
     
         6 . The composition of  claim 1 , wherein the ratio of the P-containing compound over the N-containing compound is between 0.8 and 2.5  
     
     
         7 . The composition of  claim 1 , wherein the ratio of the P-containing compound over the N-containing compound is higher than 1.0  
     
     
         8 . The composition of  claim 7 , wherein the ratio of the P-containing compound over the N-containing compound is between 1.0 and 3.0, and preferably between 1.2 and 2.5  
     
     
         9 . The composition of  claim 1 , wherein the N-containing compound is a melamine derivative as melamine cyanurate, melamine pyrophosphate or melamine polyphosphate.  
     
     
         10 . The composition of  claim 1 , wherein the phosphorus-based compound is a bisphenolic diphosphate as bisphenol A-diphosphate.  
     
     
         11 . The composition of  claim 1 , wherein the phosphorus-based compound is a phosphoramide compound as tetraxylyl piperazine diphosphoramide.  
     
     
         12 . The composition of  claim 1 , wherein the anti-dripping agent is present in an amount of 0.02-2 weight percent of the total composition, and preferably in an amount between 0.05 and 1 weight percent.  
     
     
         13 . The composition of  claim 1 , wherein the anti-dripping agent is poly(tetrafluoroethylene).  
     
     
         14 . The composition of  claim 1 , further comprising up to about 60 weight percent of alumina, amorphous silica, anhydrous aluminum silicates, mica, feldspar, clays, talc, glass flake, glass fibers, glass microspheres, wollastonite, metal oxides such as titanium dioxide, zinc oxide, ground quartz, and mixtures thereof.