Direct coupling of melt polymerization and solid state processing for PET
AssigneeEastman Chemical Company
InventorRichard Gill Bonner
Life of this patent
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Abstract
Strands of molten polyethylene terephthalate (PET) from a PET polycondensation reactor are solidified, pelletized, and cooled only to a temperature in the range of 50° C. to a temperature near the polymer Tg by contact with water. The still hot pellets are conveyed, optionally followed by drying to remove water, to a PET crystallizer. By avoiding cooling the amorphous pellets to room temperature with water and cool air, significant savings of energy are realized.
Claims48
A process for decreasing energy usage in a polyethylene terephthalate production process comprising
- a) solidifying a molten polyethylene terephthalate to form amorphous polyethylene terephthalate pellets and cooling the pellets to a temperature from about 50° C. to about the Tg of the polyethylene terephthalate to form warm polyethylene terephthalate pellets;
- and
- b) conveying said warm polyethylene terephthalate pellets to a crystallizer, wherein the temperature of the warm polyethylene terephthalate pellets is in the range of about 50° C. to below the Tg of the polyethylene terephthalate at an inlet of the crystallizer.
A process for decreasing energy usage in a polyethylene terephthalate production process comprising:
- a) solidifying a molten polyethylene terephtha late to form amorphous polyethylene terephthalate pellets and cooling the pellets to a temperature from about 50° C. to about the Tg of the polyethylene terephthlate to form warm polyethylene terephthlate pellets;
- b) conveying said warm polyethylene terephthlate pellets to a crystallizer, wherein the temperature of the warm polyethylene terephthalate pellets is in a range of about 50° C. to below the Tg of the polyethylene terephthalate inlet of the crystallizer;
- c) crystallizing said pellets in a crystallizer:
- i) over a period of 30 to 90 minutes;
- ii) at a temperature between 160° C. and 190° C.;
- or
- iii) both.
A process for decreasing energy usage in a polyethylene terephthalate production process comprising:
- a) solidifying a molten polyethylene terephthalate to form amorphous polyethylene terephthalate pellets and cooling the pellets to a temperature from about 50° C. to about the Tg of the polyethylene terephthalate to form warm polyethylene terephthalate pellets;
- b) introducing the warm pellets into a stream of gas, and conveying said warm pellets in the stream of gas to a crystallizer, wherein the temperature of the warm polyethylene terephthalate pellets is in the range of about 50° C. to below the Tg of the polyethylene terephthalate at an inlet of the crystallizer.
Dependencies are inferred from the claim text.