Thermoplastic polymers

Abstract

Thermoplastic polymers, for example fluoropolymers, are foamed by use of a solid formulation comprising thermoplastic polymer and manganese oxalate.

1 . A formulation for use in preparing a foamed thermoplastic polymer, said formulation comprising a thermoplastic polymer and an oxalate compound. 
     
     
         2 . (canceled) 
     
     
         3 . A formulation according to  claim 1 , wherein said oxalate compound comprises manganese oxalate. 
     
     
         4 . A formulation according to  claim 3 , wherein said formulation includes less than 0.5 wt % water. 
     
     
         5 . A formulation according to  claim 3 , which includes 0.2 to 30 parts by weight (pbw) of said oxalate compound and 70 to 99.8 pbw of said thermoplastic polymer. 
     
     
         6 . A formulation according to  claim 3 , which includes a masterbatch which includes 1 pbw to 30 pbw of said oxalate compound and 70 to 99 pbw of said thermoplastic polymer. 
     
     
         7 . A formulation according to  claim 3 , wherein said formulation is a solid having a melting point of at least 250° C. 
     
     
         8 . A formulation according to  claim 3 , wherein said formulation is in the form of pellets which are homogenous, wherein said pellets include 1 to 11 pbw total oxalate compounds, 0 to 11 pbw total nucleators and 100 pbw in total of thermoplastic polymers. 
     
     
         9 . (canceled) 
     
     
         10 . A formulation according to  claim 8  wherein the sum of the pbw of all blowing agents in the pellets is 10 pbw or less based on 100 pbw in total of thermoplastic polymers. 
     
     
         11 . A formulation according to  claim 3 , wherein said pellets include 1 to 10 wt % of said oxalate compound, 0 to 10 wt % of said nucleator and 89 to 99 wt % of said thermoplastic polymer. 
     
     
         12 . A formulation according to  claim 3 , wherein, in said pellets, the sum of the wt % of manganese oxalate and thermoplastic polymer(s) is at least 98 wt %. 
     
     
         13 . (canceled) 
     
     
         14 . A formulation according to  claim 3 , wherein said thermoplastic polymer is a fluoropolymer. 
     
     
         15 . A method of preparing a foamed thermoplastic polymer which comprises subjecting a mixture comprising an oxalate compound and a thermoplastic polymer to a temperature of greater than 300° C. 
     
     
         16 .- 18 . (canceled) 
     
     
         19 . A method according to  claim 15  wherein said thermoplastic polymer to be foamed is a fluoropolymer and the method comprises:
 selecting a masterbatch comprising said thermoplastic polymer and manganese oxalate; 
 contacting said masterbatch with said thermoplastic polymer; and 
 subjecting a mixture comprising said masterbatch and said thermoplastic polymer to a temperature of greater than 300° C. 
 
     
     
         20 . A method according to  19 , wherein said thermoplastic polymer to be foamed is FEP. 
     
     
         21 . (canceled) 
     
     
         22 . A method according to  claim 19 , wherein the total amount of oxalate compounds in said mixture is in the range 0.1 to 2 wt % and the total amount of thermoplastic polymers in said mixture is in the range 98 to 99.9 wt %. 
     
     
         23 .- 27 . (canceled) 
     
     
         28 . A method according to  claim 19 , wherein 1 to 36 wt % of said masterbatch is contacted with 64 to 99 wt % of said thermoplastic polymer to be foamed in the method. 
     
     
         29 . A method of making a formulation according to  claim 1 , the method comprising selecting an oxalate compound and selecting a thermoplastic polymer and contacting said oxalate compound with said thermoplastic polymer. 
     
     
         30 . (canceled) 
     
     
         31 . A method according to  claim 29  wherein, in the method, the temperature of the components does not rise above 330° C. prior to formation of pellets comprising said oxalate compound and thermoplastic polymer, wherein said oxalate compound is manganese oxalate. 
     
     
         32 . (canceled) 
     
     
         33 . A formulation according to  claim 1 , said formulation comprising a solid masterbatch which comprises a thermoplastic polymer and manganese oxalate, wherein said formulation has a melt processing temperature of at least 250° C., wherein said thermoplastic polymer is a fluoropolymer, wherein said formulation comprises 5 to 15 parts by weight of manganese oxalate and 85 to 95 parts by weight of said thermoplastic polymer. 
     
     
         34 . A formulation according to  claim 3 , wherein said thermoplastic polymer is FEP.