Method of preparing thin-walled articles

Abstract

A polymeric binder system and method of making, and a method for extruding thin-walled articles such as thin-walled tubes is provided. The extrusion method comprises providing a polymeric binder system comprising a substantially homogeneous solution of a polymeric binder and an organic solvent, adding a ceramic or metal powder to form a mixture, and evaporating the solvent from the mixture. The remaining mixture is then extruded from a die and heated to burn-off the binder and sinter the article.

1 . A thin-walled article formed by providing a polymeric binder system comprising a substantially homogeneous solution of a polymeric binder and an organic solvent; 
 adding a ceramic or metal powder to said polymeric binder system to form a mixture;    evaporating said organic solvent from said mixture;    extruding the remaining mixture from a die to form a thin-walled green article; and    heating said extruded thin-walled green article to burn-off said binder and to sinter the article.    
     
     
         2 . The thin-walled article of  claim 1  wherein said article is tubular in shape.  
     
     
         3 . A method of making a polymeric binder system for use in extruding thin-walled articles comprising: 
 providing a polymeric binder; and    dissolving said polymeric binder in an organic solvent to form a substantially homogeneous liquid.    
     
     
         4 . The method of  claim 3  wherein said polymeric binder comprises a thermoplastic block copolymer, a first thermoplastic polymer, a second thermoplastic polymer different from said first thermoplastic polymer, and a plasticizer.  
     
     
         5 . The method of  claim 4  wherein said thermoplastic block copolymer comprises a copolymer of styrene and butadiene.  
     
     
         6 . The method of  claim 4  wherein said first thermoplastic polymer comprises polystyrene.  
     
     
         7 . The method of  claim 4  wherein said second thermoplastic polymer comprises polyindene.  
     
     
         8 . The method of  claim 4  wherein said polymeric binder further includes an antioxidant.  
     
     
         9 . The method of  claim 4  wherein said plasticizer comprises at least one oil and at least one wax.  
     
     
         10 . The method of  claim 3  wherein said solvent is toluene or tetrahydrofuran.  
     
     
         11 . A polymeric binder system for use in extruding a thin-walled article comprising: 
 a polymeric binder comprising a thermoplastic block copolymer, a first thermoplastic polymer, a second thermoplastic polymer different from said first thermoplastic polymer, and a plasticizer; and    an organic solvent.    
     
     
         12 . The polymeric binder system of  claim 11  wherein said organic solvent is toluene or tetrahydrofuran.  
     
     
         13 . The polymeric binder system of  claim 11  wherein said organic solvent has been substantially evaporated from said system.  
     
     
         14 . A composition for use in extruding a thin-walled article comprising: 
 a mixture of a polymeric binder system comprising a thermoplastic block copolymer, a first thermoplastic polymer, a second thermoplastic polymer different from said first thermoplastic polymer, a plasticizer, and an organic solvent; and    a ceramic or metal powder; wherein said organic solvent has been substantially evaporated from said system.