Thermal crystallization of a molten polyester polymer in a fluid
AssigneeEastman Chemical Company
InventorsMichael Paul Ekart, Mary Therese Jernigan, Cory Lee Wells, Larry Cates Windes
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Abstract
A process for crystallizing a polyester polymer by introducing a molten polyester polymer, such as a polyethylene terephthalate polymer, into a liquid medium at a liquid medium temperature greater than the Tg of the polyester polymer, such as at a temperature ranging from 100° C. to 190° C., and allowing the molten polyester polymer to reside in the liquid medium for a time sufficient to crystallize the polymer under a pressure equal to or greater than the vapor pressure of the liquid medium. A process flow, underwater cutting process, crystallization in a pipe, and a separator are also described.
Claims82
A process for crystallizing a polyester polymer comprising introducing a molten polyester polymer, made in the melt phase polycondensation process, into a liquid medium at a liquid medium temperature greater than the Tg of the polyester polymer before the molten polyester polymer falls to a temperature below its Tg.
A process for separating a crystallized polyester polymer having an It.V., when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml, of at least 0.55 dL/g from a liquid medium comprising introducing molten polyester polymer from a melt phase polycondensation process into hot liquid medium having a temperature greater than the Tg of the polymer before the molten polyester polymer falls to a temperature below its Tg, thereafter forming a crystallized polyester polymer in the hot liquid medium, separating the crystallized polymer from the hot liquid medium under a pressure equal to or greater than the vapor pressure of the liquid medium, and directing a flow of cool liquid onto the crystallized polymer before separation, wherein the temperature of the cool liquid is less than the temperature of the hot liquid medium.
A process for crystallizing a molten polyester polymer comprising:
- a) directing molten polyester polymer from a melt phase polycondensation process through a die, and
- b) before the temperature of the molten polyester polymer falls below its Tg, first contacting the molten polyester with a liquid medium when the liquid medium temperature is greater than the Tg of the polyester polymer and crystallizing the molten polyester polymer.
A process for crystallizing a polyester polymer, comprising:
- a) directing a molten polyester polymer from a melt phase polycondensation process through a die, and
- b) before the temperature of the molten polyester polymer falls below its Tg, contacting the molten polyester with a liquid medium at a liquid medium temperature greater than the Tg of the polyester polymer for a time sufficient to provide a crystallized polyester polymer having a degree of crystallinity of at least 10%, followed by
- c) separating, under a pressure equal to or greater than the vapor pressure of the liquid medium, the crystallized polyester polymer from the liquid medium.
A process for crystallizing a polyester polymer, comprising
- a) directing a molten polyester polymer from a melt phase polycondensation process through a die, and
- b) before the temperature of the molten polyester polymer falls below its Tg,
- i) cutting the polymer into globules with a cutter;
- ii) contacting the globules with a flow of liquid medium at a liquid medium temperature greater than the Tg of the polyester polymer to form a flow of slurry;
- iii) directing the flow of slurry away from the cutter to a crystallizer and allowing the globules to reside in the crystallization zone under a pressure equal to or greater than the vapor pressure of the liquid medium for a time sufficient to impart a degree of crystallinity of at least 10% to the globules, thereby forming crystallized globules;
- and
- c) separating in a separation apparatus under a pressure equal to or greater than the vapor pressure of the liquid medium, the crystallized globules or resulting pellets from the liquid medium to form a stream of crystallized polyester polymer and a stream of separated liquid medium, wherein:
- i) at least a portion of the source of the flow of liquid medium in step bii) is the stream of separated liquid medium;
- and
- ii) the stream of crystallized polyester polymer is directed to a dyer for removing at least a portion of the residual liquid on or in the crystallized polymer.
Dependencies are inferred from the claim text.