Silicone Wax Modified Low Wear Polyoxymethylene

Abstract

A tribologically modified polyoxymethylene polymer composition is comprised of a polyoxymethylene polymer and at least one tribological modifier. The tribological modifier may comprise at least one silicone wax having a molecular weight of less than 40,000 g/mol. The composition may exhibit a dynamic coefficient of friction against a counter-material of from about 0.1 to about 0.5. The composition provides polymer articles with improved tribological properties.

1 . A polyoxymethylene polymer composition comprising
 a polyoxymethylene copolymer, and   at least one silicone wax having a molecular weight of less than 40,000 g/mol.   
     
     
         2 . The polymer composition of  claim 1 , wherein the silicone wax comprises a modified silicone wax. 
     
     
         3 . The polymer composition of  claim 1 , wherein the silicone wax has a molecular weight of less than about 30,000 g/mol. 
     
     
         4 . The polymer composition of  claim 1 , wherein the silicone wax comprises a modified polydimethylsiloxane wax. 
     
     
         5 . The polymer composition of  claim 1 , wherein the silicone wax comprises an alkyl group having more than 2 carbon atoms, an amine group, a polyether group, a hydroxyl group, or any combination thereof. 
     
     
         6 . The polymer composition of  claim 5 , wherein the silicone wax is comprised of pendant groups and wherein from about 10% to about 90% of the pendant groups are comprised of the alkyl group having more than 2 carbon atoms. 
     
     
         7 . The polymer composition of  claim 5 , wherein the silicone wax comprises a polyether group and wherein the polyether group comprises from 2 to 5 carbon atoms. 
     
     
         8 . The polymer composition of  claim 5 , wherein the silicone wax comprises a hydroxyl group and wherein the hydroxyl group has a hydroxyl value of from 5 to 150. 
     
     
         9 . The polymer composition of  claim 1 , wherein the silicone wax is present in an amount of from about 0.1 wt. % to about 10 wt. %. 
     
     
         10 . The polymer composition of  claim 1 , wherein the composition further comprises a nucleating agent in an amount of from about 0.05 wt. % to about 0.5 wt. %. 
     
     
         11 . The polymer composition of  claim 10 , wherein the nucleating agent is a polyoxymethylene terpolymer. 
     
     
         12 . The polymer composition of  claim 1 , wherein the composition further comprises an antioxidant in an amount of from about 0.05 wt % to about 0.5 wt. %. 
     
     
         13 . The polymer composition of  claim 1 , wherein the composition further comprises a formaldehyde scavenger in an amount of from about 0.005 wt. % to about 0.1 wt. %. 
     
     
         14 . The polymer composition of  claim 1 , wherein the composition further comprises an acid scavenger in an amount of from about 0.005 wt. % to about 0.1 wt. %. 
     
     
         15 . The polymer composition of  claim 1 , wherein the composition further comprises a lubricant in an amount of from about 0.05 wt. % to about 0.5 wt. %. 
     
     
         16 . The polymer composition of  claim 1 , wherein the composition has a dynamic coefficient of friction against a polyacetal surface of from about 0.1 to about 0.5. 
     
     
         17 . A polymer article comprising the composition of  claim 1 . 
     
     
         18 . A polymer article comprising a polyoxymethylene polymer composition comprising:
 a polyoxymethylene copolymer,   at least one silicone wax having a molecular weight of less than 40,000 g/mol, and   at least one of an antioxidant, a formaldehyde scavenger, a nucleating agent, an acid scavenger, a lubricant, or any combination thereof.   
     
     
         19 . The polymer article of  claim 18 , wherein the silicone wax comprises a polydimethylsiloxane wax. 
     
     
         20 . The polymer article of  claim 18 , wherein the silicone wax has a molecular weight of less than about 30,000 g/mol. 
     
     
         21 . The polymer article of  claim 18 , wherein the silicone wax comprises an alkyl group having more than 2 carbon atoms, an amine group, a polyether group, a hydroxyl group, or any combination thereof. 
     
     
         22 . The polymer article of  claim 21 , wherein the silicone wax is comprised of pendant groups and wherein from about 10% to about 90% of the pendant groups are comprised of the alkyl group having more than 2 carbon atoms. 
     
     
         23 . The polymer article of  claim 21 , wherein the silicone wax comprises a polyether group and wherein the polyether group comprises from 2 to 5 carbon atoms. 
     
     
         24 . The polymer article of  claim 21 , wherein the silicone wax comprises a hydroxyl group and wherein the hydroxyl group has a hydroxyl value of from 5 to 150. 
     
     
         25 . The polymer article of  claim 18 , wherein the composition comprises a polyoxymethylene terpolymer in an amount of from about 0.05 wt. % to about 0.5 wt. %. 
     
     
         26 . The polymer article of  claim 18 , wherein the composition comprises an antioxidant in an amount of from about in an amount of from about 0.05 wt % to about 0.5 wt. %, a formaldehyde scavenger in an amount of from about 0.005 wt. % to about 0.1 wt. %, an acid scavenger in an amount of from about 0.005 wt. % to about 0.1 wt. %, a lubricant in an amount of from about 0.05 wt. % to about 0.5 wt. %, or any combination thereof. 
     
     
         27 . The polymer article of  claim 18 , wherein the article exhibits a dynamic coefficient of friction against a polyacetal surface of from about 0.1 to about 0.5.