Flame retardant non halogenated silicone composition for high temperature and automotive and building construction applications

Abstract

Blends of a non-halogenated, formaldehyde-cured silicone rubber are described. The blend includes magnesium oxide and zinc borate. The compositions exhibit thermal stability at high temperatures as well as improved chemical resistance.

1 . A thermally stable polymeric blend that does not char or deteriorate at a temperature of up to 700° F. comprising magnesium oxide and a non-halogenated, formaldehyde-cured silicone rubber. 
   
   
       2 . The composition according to  claim 1  further comprising about 2 to about 15% by weight of a synergist. 
   
   
       3 . The composition according to  claim 2  wherein said synergist is magnesium hydroxide. 
   
   
       4 . The composition according to  claim 1  wherein said magnesium oxide is present in an amount of about 4 to about 8 weight percent. 
   
   
       5 . The composition according to  claim 4  wherein said magnesium oxide is present in an amount of about 5 to about 7 weight percent. 
   
   
       6 . The composition according to  claim 1  wherein said zinc borate is present in an amount of about 11 to about 14 weight percent. 
   
   
       7 . A method of forming a thermally stable composition comprising blending about 10 to about 15% by weight zinc borate and about 2 to about 10% by weight magnesium oxide and the balance of the composition being a non- halogenated, formaldehyde-cured silicone rubber. 
   
   
       8 . The method according to  claim 7  further comprising blending said compositions with about 2 to about 15% by weight of a synergist. 
   
   
       9 . The method according to  claim 8  wherein said synergist is magnesium hydroxide. 
   
   
       10 . The method according to  claim 7  wherein said magnesium oxide is present in an amount of about 4 to about 8 weight percent. 
   
   
       11 . The method according to  claim 7  wherein said magnesium oxide is present in an amount of about 5 to about 7 weight percent. 
   
   
       12 . The method according to  claim 7  wherein said zinc borate is present in an amount of about 11 to about 14 percent by weight. 
   
   
       13 . A polymeric blend comprising a silicone rubber, zinc borate and magnesium oxide and wherein said silicone rubber is a formaldehyde-cured silicone rubber. 
   
   
       14 . (canceled) 
   
   
       15 . The polymeric blend according to  claim 13  where said silicone rubber is non-halogenated. 
   
   
       16 . (canceled) 
   
   
       17 . The composition according to  claim 13  further comprising about 2 to about 15% by weight of a synergist. 
   
   
       18 . The composition according to  claim 13  wherein said synergist is magnesium hydroxide. 
   
   
       19 . The composition according to  claim 13  wherein said magnesium oxide is present in an amount of about 4 to about 8 weight percent. 
   
   
       20 . (canceled) 
   
   
       21 . The composition according to  claim 13  wherein said zinc borate is present in an amount of about 11 to about 14 weight percent. 
   
   
       22 . The composition according to  claim 1  wherein the magnesium oxide comprises about 2 to about 10% by weight of the composition. 
   
   
       23 . The composition according to  claim 1  wherein the zinc borate comprises about 10 to about 15% by weight of the composition.