Extrusion process
View Patent ↗The present invention relates to the extrusion of a composition comprising tetrafluoroethylene/hexafluoropropylene copolymer, 10-60 wt % inorganic particulate filler, and hydrocarbon polymer for dispersing the filler in the copolymer, preferably 0.1 to 5 wt % hydrocarbon polymer, at low temperatures, e.g. up to 650° F. (343° C.).
1. A process comprising extruding a composition comprising tetrafluoroethylene/hexafluoropropylene copolymer, about 10-60 wt % inorganic particulate filler, and an effective amount of hydrocarbon polymer to disperse said particulate filler in said copolymer either during melt blending prior to said extruding of said composition or during said extruding, the amount of said copolymer, filler and polymer totaling 100 wt %, wherein said extruding is carried out at a melt temperature ranging from about 520° F. (271° C.) to 650° F. (343° C.), said effective amount of hydrocarbon polymer being about 0.5 to 3 wt %, wherein said copolymer and said hydrocarbon polymer are incompatible to one another and said hydrocarbon polymer is an aromatic-containing thermoplastic elastomer.
2. The process of claim 1 wherein 20 to 50 wt % of said inorganic particulate filler is present.
3. The process of claim 1 wherein the dispersion of said particulate filler in said copolymer is characterized by said composition having an elongation of at least about 150% in accordance with ASTM D 3032.
4. The process of claim 1 wherein said extruding is carried out at a melt temperature of said composition of about 560° F. (293° C.) to 620° F. (326° C.).
5. The process of claim 1 wherein said particulate filler has an average particle size of less than about 3 micrometers.
6. The process of claim 1 wherein said extruding is to form cable jacket and said extruding is carried out at a speed of at least about 300 ft/min (91.5 m/min).
7. The process of claim 6 wherein said extruding is carried out at a draw down ratio of no greater than about 40:1.
8. The process of claim 1 wherein said filler comprises a plurality of fillers.
9. The process of claim 8 , wherein at least one of said fillers is ceramic microspheres.
10. The process of claim 1 wherein said copolymer has a melt flow rate of at least about 10 g/10 min.
11. A process comprising extruding a composition comprising tetrafluoroethylene/hexafluoropropylene copolymer, 20 to 50 wt % inorganic particulate filler, about 0.1 to 5 wt % of hydrocarbon polymer to disperse said particulate filler in said copolymer either during melt blending prior to said extruding of said composition or during said extruding, the amount of said copolymer, filler and polymer totaling 100 wt %, wherein said extruding is carried out at a melt temperature ranging from about 560° F. (293° C.) to 620° F. (326° C.) to form cable jacket, wherein said copolymer and said hydrocarbon polymer are incompatible to one another and said hydrocarbon polymer is an aromatic-containing thermoplastic elastomer.