Stabilizers for polymers containing aliphatically-bound bromine

Abstract

Aliphatic bromine-containing polymers are stabilized using a mixture of an alkyl phosphite and an epoxy compound. This stabilizer package is very effective at preventing cross-linking reactions from occurring when the aliphatic bromine-containing polymer is subjected to high temperatures as are seen in melt processing operations. The stabilized aliphatic bromine-containing polymer is useful as a flame retardant for other polymers, notably polystyrene foam.

1 . A polymer composition comprising (a) a bulk polymer, (b) an aliphatic bromine-containing polymer, and (c) at least one alkyl phosphite, at least one epoxy compound or a mixture of at least one alkyl phosphite and at least one epoxy compound. 
     
     
         2 . The polymer composition of  claim 1 , wherein from 1 to 40 parts by weight of the epoxy compound are present per 100 parts by weight of the aliphatic bromine-containing polymer. 
     
     
         3 . The polymer composition of  claim 1 , wherein from 1 to 40 parts by weight of the alkyl phosphite are present per 100 parts by weight of the aliphatic bromine-containing polymer. 
     
     
         4 . The polymer composition of  claim 1 , wherein the aliphatic bromine-containing polymer is a brominated butadiene homopolymer or a brominated styrene/butadiene block copolymer. 
     
     
         5 . The polymer composition of  claim 1  wherein the aliphatic bromine-containing polymer is a copolymer of styrene and allylmaleimide; an aliphatically unsaturated polyester; an allyl ether of a novolac novolac resin, or a ROMP polymer or copolymer. 
     
     
         6 . The polymer composition of  claim 1  wherein the bulk polymer is a polymer or copolymer of styrene. 
     
     
         7 . The polymer composition of  claim 2 , which is in the form of a foam. 
     
     
         8 . The polymer composition of  claim 1 , wherein the alkyl phosphite contains at least one 
       
         
           
           
               
               
           
         
         moiety, in which each R group is an unsubstituted or substituted, linear or branched, alkyl group, or the two R groups together form a divalent group, which may be substituted, that bonds to the adjacent —O— atoms through an aliphatic carbon to form a ring structure that includes a —O—P—O— linkage, and the R 1  group is another R group, or an aryl or substituted aryl group. 
       
     
     
         9 . The polymer composition of  claim 1 , wherein the alkyl phosphite is a pentaerythritol diphosphite compound having the structure 
       
         
           
           
               
               
           
         
         wherein each R 2  is an unsubstituted or substituted, linear or branched, alkyl group, an aryl group or a substituted aryl group. 
       
     
     
         10 . The polymer composition of  claim 9 , wherein the alkyl phosphite is bis(2,4-dicumylphenyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite or di(2,4-di-(t-butyl)phenyl)pentaerythritol diphosphite. 
     
     
         11 . A method for producing a polymer composition of  claim 1 , comprising melt processing a mixture containing a molten bulk polymer and an aliphatic bromine-containing polymer or copolymer in the presence of (1) at least one alkyl phosphite, (2) at least one epoxy compound or (3) a mixture of at least one alkyl phosphite and at least one epoxy compound. 
     
     
         12 - 15 . (canceled)