Extrusion of polyurethane composite materials

Abstract

Methods of extruding polyurethane composite materials are described. One method includes introducing at least one polyol and inorganic filler to a first conveying section of the extruder, transferring the at least one polyol and inorganic filler to a first mixing section of an extruder, mixing the at least one polyol and the inorganic filler in the first mixing section, transferring the mixed at least one polyol and inorganic filler to a second conveying section of the extruder, introducing a di- or poly-isocyanate to the second conveying section, transferring the mixed at least one polyol and inorganic filler and the di- or poly-isocyanate to a second mixing section, mixing the mixed at least one polyol and inorganic filler with the di- or poly-isocyanate in the second mixing section of the extruder to provide a composite mixture, and transferring the composite mixture to an output end of the extruder. Other related methods are also described.

1 . A method of forming a polymeric composite material in an extruder, the method comprising:
 introducing at least one polyol and inorganic filler to a first conveying section of the extruder;   transferring the at least one polyol and inorganic filler to a first mixing section of an extruder;   mixing the at least one polyol and the inorganic filler in the first mixing section;   transferring the mixed at least one polyol and inorganic filler to a second conveying section of the extruder;   introducing a di- or poly-isocyanate to the second conveying section;   transferring the mixed at least one polyol and inorganic filler and the di- or poly-isocyanate to a second mixing section;   mixing the mixed at least one polyol and inorganic filler with the di- or poly-isocyanate in the second mixing section of the extruder to provide a composite mixture; and   transferring the composite mixture to an output end of the extruder.   
     
     
         2 . The method of  claim 1 , wherein the extruder is a twin screw extruder. 
     
     
         3 . The method of  claim 1 , wherein the composite mixture comprises about 40 to about 85 weight percent of the inorganic filler. 
     
     
         4 . The method of  claim 1 , wherein the composite mixture comprises about 60 to about 85 weight percent of the inorganic filler. 
     
     
         5 . The method of  claim 1 , wherein the composite mixture comprises about 65 to about 80 weight percent of the inorganic filler. 
     
     
         6 . The method of  claim 1 , wherein the inorganic filler is fly ash. 
     
     
         7 . The method of  claim 1 , wherein the first conveying section comprises one or more transfer screws. 
     
     
         8 . The method of  claim 1 , wherein the first mixing section comprises a slotted screw. 
     
     
         9 . The method of  claim 1 , wherein the first mixing section comprises a lobal screw. 
     
     
         10 . The method of  claim 1 , wherein the first mixing section comprises a lobal screw and a slotted screw. 
     
     
         11 . The method of  claim 1 , wherein the second conveying section comprises a transfer screw. 
     
     
         12 . The method of  claim 1 , wherein the second mixing section comprises a reverse screw. 
     
     
         13 . The method of  claim 12 , wherein the reverse screw comprises a reverse slotted screw. 
     
     
         14 . The method of  claim 1 , further comprising adding one or more components of the composite mixture in the first conveying section of the extruder, the one or more components being selected from the group consisting of a catalyst, a surfactant, and a blowing agent. 
     
     
         15 . The method of  claim 14 , further comprising blending the one or more components with the at least one polyol prior to introduction to the first conveying section. 
     
     
         16 . The method of  claim 1 , further comprising mixing the mixed at least one polyol and inorganic filler and the di- or poly-isocyanate in a third mixing section subsequent to the second conveying section and prior to the second mixing section. 
     
     
         17 . The method of  claim 16 , wherein the third mixing section comprises a reverse screw. 
     
     
         18 . The method of  claim 16 , further comprising introducing fibrous material in a third conveying section, the third conveying section being located between the second mixing section and the third mixing section. 
     
     
         19 . The method of  claim 1 , further comprising introducing fibrous material in the second conveying section. 
     
     
         20 . The method of  claim 19 , further comprising mixing the fibrous material with the mixed at least one polyol and inorganic filler and the di- or poly-isocyanate in the second mixing section.