초록 ▼

An apparatus and process maintain control of the temperature of low-melting compounds, high melt flow polymers, and thermally sensitive materials for the pelletization of such materials. The addition of a cooling extruder, and a second melt cooler if desired, in advance of the die plate provides for

An apparatus and process maintain control of the temperature of low-melting compounds, high melt flow polymers, and thermally sensitive materials for the pelletization of such materials. The addition of a cooling extruder, and a second melt cooler if desired, in advance of the die plate provides for regulation of the thermal, shear, and rheological characteristics of narrow melting-range materials and polymeric mixtures, formulations, dispersions or solutions. The apparatus and process can then be highly regulated to produce consistent, uniform pellets of low moisture content for these otherwise difficult materials to pelletize.

대표청구항 ▼

1. A method for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line including a pelletizer with an extrusion die, the method comprising the steps of: forming a melt of a material difficult to be pelletized; passing the melt through a heat exchanger locate

1. A method for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line including a pelletizer with an extrusion die, the method comprising the steps of: forming a melt of a material difficult to be pelletized; passing the melt through a heat exchanger located upstream of a cooling extruder to cool the melt in advance of said cooling extruder; directly passing said melt into and through the cooling extruder from said heat exchanger, said cooling extruder processing and mixing said melt to increase dispersive homogeneity of the melt and to further cool the melt to an appropriate temperature for extrusional pelletization; feeding the melt into said extrusion die of said pelletizer located downstream of said cooling extruder; pelletizing the melt into pellets in said pelletizer; and drying said pellets in a dryer. 2. The method as claimed in claim 1, wherein the pelletizing step is carried out in an underwater, hot face, strand or water ring pelletizer. 3. The method as claimed in claim 1, wherein the pelletizing step is carried out in an underwater pelletizer. 4. The method as claimed in claim 1, wherein the pelletizing step is carried out in a hot face pelletizer. 5. The method as claimed in claim 1, wherein said step of forming a melt to be pelletized includes filtering the melt and pressurizing the melt sufficiently to ensure its passage through the cooling extruder and through said extrusion die of said pelletizer. 6. The method as claimed in claim 1, wherein, after said melt is passed through said cooling extruder, the melt is further pressurized and passed through a screen changer before entering said extrusion die of the pelletizer. 7. The method as claimed in claim 1, wherein said step of forming a melt to be pelletized includes passing the melt through a diverter valve in order to divert said melt from the processing line when desired. 8. The method as claimed in claim 1, wherein the step of passing the melt through the cooling extruder includes the addition of thermally sensitive ingredients through one or more feeders of said cooling extruder. 9. The method as claimed in claim 8, wherein said sensitive ingredients may be solid or liquid and selected from the group consisting of rheological additives, miscibilizing agents, surfactants, expanding agents, catalysts, inhibitors, antioxidants, chain extenders, nucleation agents, flavors, fragrances, colorants, devolatilizing agents, and chemical scavengers. 10. The method as claimed in claim 1, wherein, after passing said melt through said cooling extruder, the melt is passed through a second heat exchanger located downstream of said cooling extruder for additional regulation of the temperature and final mixing of the melt before entering said extrusion die of the pelletizer. 11. The method as claimed in claim 1, wherein, before passing said melt through said heat exchanger, the melt is passed through a first extruder for shear mixing and melting. 12. The method as claimed in claim 1, wherein said cooling extruder is selected from a single, twin, multiple screw, or a ring extruder. 13. An apparatus for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line comprising: a mixing device for forming a melt of a material difficult to be pelletized; a pelletizer having an extrusion die; a heat exchanger located downstream of said mixing device and upstream of said pelletizer, said heat exchanger configured to cool said melt received from said mixing device; a cooling extruder located upstream of said pelletizer and extrusion die and directly downstream of said heat exchanger, said cooling extruder configured to process and mix said melt to increase the dispersive homogeneity of the melt and to cool the melt to an appropriate temperature for extrusional pelletization before introduction into said extrusion die of the pelletizer; and a drying component located downstream of said pelletizer. 14. The apparatus as claimed in claim 13, wherein the pelletizer is an underwater, hot face, strand or water ring pelletizer. 15. The apparatus as claimed in claim 13, wherein the pelletizer is an underwater pelletizer. 16. The apparatus as claimed in claim 13, wherein the pelletizer is a hot face pelletizer. 17. The apparatus as claimed in claim 13, wherein said processing line includes one or more pumps sufficient to pressurize the melt to ensure its passage through the cooling extruder and through said extrusion die of said pelletizer. 18. The apparatus as claimed in claim 13, wherein said processing line includes one or more pumps after said cooling extruder to further pressurize said melt before entering said extrusion die of the pelletizer. 19. The apparatus as claimed in claim 13, wherein said processing line includes a diverter valve in advance of said cooling extruder to divert the melt from the processing line when desired. 20. The apparatus as claimed in claim 13, wherein said cooling extruder includes one or more feeders for the addition of one or more thermally sensitive ingredients. 21. The apparatus as claimed in claim 20, wherein said one or more feeders are configured to add sensitive ingredients that may be solid or liquid and selected from the group consisting of rheological additives, miscibilizing agents, surfactants, expanding agents, catalysts, inhibitors, antioxidants, chain extenders, nucleation agents, flavors, fragrances, colorants, devolatilizing agents, and chemical scavengers. 22. The apparatus as claimed in claim 13, wherein said processing line includes a second heat exchanger after said cooling extruder for additional regulation of the temperature and final mixing of the melt before entering said extrusion die of the pelletizer. 23. The apparatus as claimed in claim 13, wherein said mixing device in said processing line includes a first extruder positioned upstream of said heat exchanger, said melt passing through said first extruder for shear mixing and melting before passing into said heat exchanger. 24. The apparatus as claimed in claim 13, wherein said cooling extruder is a single, twin, multiple screw, or a ring extruder. 25. The apparatus as claimed in claim 13, wherein said heat exchanger is a coil-type, scrape wall, plate and frame, or a shell and tube design with or without static mixers, or a U-style tube design with or without static mixers. 26. The apparatus as claimed in claim 23, wherein said processing line includes a second heat exchanger after said cooling extruder for additional regulation of the temperature and final mixing of the melt before entering said extrusion die of the pelletizer. 27. The method as claimed in claim 11, wherein, after the melt has passed through the cooling extruder, the melt is passed through a second heat exchanger located downstream of said cooling extruder for additional regulation of the temperature and final mixing of the melt before entering said extrusion die of the pelletizer. 28. A method for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line including a pelletizer with an extrusion die, the method comprising the steps of: forming a melt to be pelletized;passing the melt through a heat exchanger located upstream of a cooling extruder to cool the melt in advance of said cooling extruder;passing said melt through the cooling extruder for processing and mixing to increase dispersive homogeneity of the melt and to further cool the melt to an appropriate temperature for extrusional pelletization and, while passing said melt through the cooling extruder, adding at least one thermally sensitive ingredient into said melt while in said cooling extruder through one or more feeders;feeding the melt into said extrusion die of said pelletizer located downstream of said cooling extruder;pelletizing the melt into pellets in said pelletizer; anddrying said pellets in a dryer. 29. An apparatus for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line comprising: a mixing device for forming a melt to be pelletized;a pelletizer having an extrusion die;a heat exchanger located downstream of said mixing device and upstream of said pelletizer, said heat exchanger configured to cool said melt received from said mixing device;a cooling extruder located downstream of said heat exchanger and upstream of said pelletizer and extrusion die, said cooling extruder configured to receive cooled melt from said heat exchanger through an extruder inlet and to then process and mix said melt in said extruder to increase the dispersive homogeneity of the melt and to cool the melt to an appropriate temperature for extrusional pelletization before introduction into said extrusion die of the pelletizer;said cooling extruder including one or more feeders separate from and downstream of said extruder inlet for the addition of one or more thermally sensitive ingredients into said melt while said melt is being processed in said cooling extruder; anda drying component located downstream of said pelletizer. 30. A method for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line including a pelletizer with an extrusion die, the method comprising the steps of: forming a melt to be pelletized;passing the melt through a first extruder for shear mixing and melting;passing the melt through a heat exchanger located downstream of said first extruder and upstream of a cooling extruder to cool the melt in advance of said cooling extruder;passing said melt through the cooling extruder for processing and mixing to increase dispersive homogeneity of the melt and to further cool the melt to an appropriate temperature for extrusional pelletization;feeding the melt into said extrusion die of said pelletizer located downstream of said cooling extruder;pelletizing the melt into pellets in said pelletizer; anddrying said pellets in a dryer. 31. An apparatus for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line comprising: a mixing device for forming a melt to be pelletized, said mixing device including a first extruder through which said melt passes for shear mixing and melting;a pelletizer having an extrusion die;a heat exchanger located downstream of said mixing device and upstream of said pelletizer, said heat exchanger configured to cool said melt received from said mixing device;a cooling extruder located downstream of said heat exchanger and upstream of said pelletizer and extrusion die, said cooling extruder configured to process and mix said melt to increase the dispersive homogeneity of the melt and to cool the melt to an appropriate temperature for extrusional pelletization before introduction into said extrusion die of the pelletizer; anda drying component located downstream of said pelletizer. 32. An apparatus for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line comprising: a mixing device for forming a melt to be pelletized;a pelletizer having an extrusion die;a heat exchanger located downstream of said mixing device and upstream of said pelletizer, said heat exchanger configured to cool said melt received from said mixing device;a cooling extruder located downstream of said heat exchanger and upstream of said pelletizer and extrusion die, said cooling extruder configured to process and mix said melt to increase the dispersive homogeneity of the melt and to cool the melt to an appropriate temperature for extrusional pelletization;one or more pumps located downstream of said cooling extruder and upstream of said pelletizer and extrusion die to further pressurize said melt before entering said extrusion die of the pelletizer; anda drying component located downstream of said pelletizer. 33. A method for pelletizing materials which are otherwise difficult to pelletize in a pelletizer processing line including a pelletizer with an extrusion die, the method comprising the steps of: forming, in a mixing device, a melt to be pelletized;cooling said melt received from said mixing device in a heat exchanger located downstream of said mixing device and upstream of said pelletizer and said extrusion die;processing and mixing said melt using a cooling extruder located downstream of said heat exchanger and upstream of said pelletizer and extrusion die, said processing and mixing of said melt increasing the dispersive homogeneity of the melt and further cooling the melt to an appropriate temperature for extrusional pelletization;pressurizing said melt before entering said extrusion die of the pelletizer using one or more pumps located downstream of said cooling extruder and upstream of said pelletizer and extrusion die;pelletizing the melt into pellets in said pelletizer using said extrusion die; andpassing said pellets to a drying component located downstream of said pelletizer.