Direct coupling of melt polymerization and solid state processing for PET
First Claim
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1. A process for decreasing energy usage in a polyethylene terephthalate production process comprisinga) 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.
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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.
61 Citations
48 Claims
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1. 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
- C. to about the Tg of the polyethylene terephthalate to form warm polyethylene terephthalate pellets; and
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20. A process for decreasing energy usage in a polyethylene terephthalate production process comprising:
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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.;
oriii) both. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A process for decreasing energy usage in a polyethylene terephthalate production process comprising:
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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. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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Specification