Thermal crystallization of a molten polyester polymer in a fluid

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 T g 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.

1 - 59 . (canceled)  
   
   
       60 . A process for separating a crystallized polyester polymer having an It.V. of at least 0.55 dL/g from a liquid medium comprising separating said polymer from said liquid medium under a pressure equal to or greater than the vapor pressure of the liquid medium, drying the separated crystallized polyester polymer, and following separation and before drying, directing a flow of cool liquid onto the separated crystallized polyester polymer, wherein the temperature of the cool liquid is less than the temperature of the separated crystallized polyester polymer.  
   
   
       61 . The process of  claim 60 , wherein the polymer has a degree of crystallinity of at least 20%.  
   
   
       62 . A process for crystallizing a polyester polymer, comprising introducing a polyester polymer to a feed of liquid medium, crystallizing the polymer in the liquid medium, separating the polymer from the liquid medium, removing residual liquid medium on or around the separated polymer in a dryer, and re-circulating at least a portion of the removed liquid medium from the dryer to or as said feed of liquid medium.  
   
   
       63 . A process for crystallizing a polyester polymer comprising introducing a polyester polymer to a feed of liquid medium, crystallizing the polymer in the liquid medium and in the absence of rotating mechanically induced agitation, separating the polymer and the liquid medium from each other, and directing at least a portion of the separated liquid medium to or as said feed of liquid medium.  
   
   
       64 . The process of  claim 63 , wherein said polyester polymer is introduced as a molten polyester polymer having an It.V. of at least 0.55 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       65 . The process of  claim 64 , wherein the polyester polymer comprises a polyethylene terephalate or naphthalate homopolymer or copolymer modified with 40% or less of a repeat unit or units other than ethylene terephthalate  
   
   
       66 . The process of  claim 65 , wherein the liquid medium temperature is at least 130° C.  
   
   
       67 . A process for making an article comprising contacting a molten 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/1 00 ml, of 0.70 dL/g or more with a liquid medium at a liquid medium temperature sufficient to induce crystallinity to the molten polyester polymer, allowing the molten crystallized polymer to cool to a pellet, isolating the pellets without increasing the molecular weight of the pellet in the solid state, and melt processing the pellets into a shaped article.  
   
   
       68 . The process of  claim 67 , wherein the liquid medium temperature is above 100° C.  
   
   
       69 . The process of  claim 68 , wherein the liquid medium temperature ranges from 140° C. to 180° C.  
   
   
       70 . The process of  claim 67 , wherein the polyester polymer comprises at least 60 mole % ethylene units based on the moles of all diols added and at least 60 mole % terephthalate units or naphthalate units based on the moles of all dicarboxylic acids added.  
   
   
       71 . The process of  claim 67 , wherein the molten polyester polymer is extruded in an extruder through a die at a temperature of 190° C. or more as measured at the extruder nozzle.  
   
   
       72 . The process of  claim 67 , wherein the molten polyester polymer is cut underfluid.  
   
   
       73 . The process of  claim 72 , wherein the liquid medium comprises water.  
   
   
       74 . The process of  claim 67 , comprising allowing the molten polyester polymer to reside in the liquid medium at a liquid medium temperature above the T g  of the polyester polymer for a time sufficient to impart to the molten polyester polymer a degree of crystallinity of at least 25%.  
   
   
       75 . The process of  claim 67 , comprising crystallizing the molten polyester polymer in the liquid medium at a pressure on the liquid medium which is equal to or higher than the vapor pressure of the liquid medium.  
   
   
       76 . The process of  claim 75 , comprising a pressure on the liquid medium of greater than 25 psia.  
   
   
       77 . The process of  claim 67 , comprising crystallizing the molten polyester polymer in a pipe for a time sufficient to impart to the molten polyester polymer a degree of polymerization of at least 20%, and the molten polyester polymer travels in the same direction as the liquid medium in the pipe.  
   
   
       78 . The process of  claim 67 , wherein the residence time of the molten polyester polymer or globules made from the molten polyester polymer in said liquid medium to obtain a degree of crystallinity of 20% or more is 10 minutes or less.  
   
   
       79 . The process of  claim 78 , wherein the degree of crystallinity is 30% or more at a residence time of 4 minutes or less.  
   
   
       80 . The process of  claim 67 , wherein crystallization is conducted in the absence of rotating mechanically induced agitation.  
   
   
       81 . A process for making a molded part or sheet from pellets comprising: 
 d) drying polyester pellets crystallized from molten polyester polymer;    e) introducing the dried pellets into an extrusion zone to form molten PET polymer; and    f) forming a sheet, strand, fiber, or a molded part from extruded molten PET polymer.    
   
   
       82 . The process of  claim 81 , wherein said pellets have an It.V. ranging from 0.7 to 1.15 dL/g.  
   
   
       83 . The process of  claim 81 , wherein said pellets are dried in a said drying zone at a zone temperature of at least 140° C.  
   
   
       84 . The process of  claim 81 , wherein the residence time of the pellets in the drying zone ranges from 0.50 hours to 16 hours.  
   
   
       85 . The process of  claim 81 , wherein the temperature in the drying zone ranges from 140° C. to 180° C.  
   
   
       86 . The process of  claim 81 , wherein the PET pellets have an average degree of crystallization ranging from 25% to 50%.  
   
   
       87 . The process of  claim 81 , wherein the molten polyester polymer is crystallized at a temperature greater than or equal to 40° C. below the drying temperature.  
   
   
       88 . The process of  claim 81 , comprising forming a bottle preform.  
   
   
       89 . The process of  claim 81 , comprising forming a thermoformable sheet.  
   
   
       90 - 106 . (canceled)  
   
   
       107 . A process for underfluid cutting a molten polyester polymer comprising a die plate having an inner surface disposed toward a cutter each contained within a housing having an inlet and an outlet, and continuously directing a flow of hot liquid medium having a first temperature through the inlet and exiting through the outlet and continuously directing a flow of a cool liquid medium having a second temperature into the housing, wherein the first temperature is higher than the second temperature.  
   
   
       108 . The process of claim  90 , wherein the flow of cool liquid medium is directed into the housing through the hot liquid medium in the housing and impinges on inner surface of the die plate, the cutter, or both, wherein the flow of hot liquid medium and the flow of cool liquid medium in the housing are in contact with each other.  
   
   
       109 . A process for thermally crystallizing a molten polyester polymer in a pipe comprising directing a flow of molten polyester polymer in a liquid medium through a pipe having an aspect ratio L/D of at least 15:1, wherein the molten polyester polymer is crystallized in the pipe at a liquid medium temperature greater than the T g  of the polyester polymer.  
   
   
       110 . The process of  claim 109 , wherein the molten polyester polymer is crystallized in said pipe at a liquid medium temperature exceeding the boiling point of the liquid medium at 1 atmosphere.  
   
   
       111 . The process of  claim 109 , wherein the molten polyester polymer is crystallized in said pipe at a liquid medium temperature of at least 140° C.  
   
   
       112 . The process of  claim 109 , wherein the molten polyester polymer and liquid medium in said pipe are under a pressure equal to or greater than the vapor pressure of the liquid medium.  
   
   
       113 . The process of  claim 109 , wherein the pipe has an aspect ratio L/D of at least 25:1, the molten polyester polymer are crystallized in said pipe at a liquid medium temperature of at least 140° C., the molten polyester polymer and liquid medium in said pipe are under a pressure equal to or greater than the vapor pressure of the liquid medium, and the molten polyester polymer is crystallized to a degree of at least 20% in the pipe.  
   
   
       114 . The process of  claim 109 , comprising crystallizing said solid molten polyester polymer in said pipe to a degree of crystallinity of at least 30%.  
   
   
       115 . The process of  claim 109 , comprising introducing solid polyester molten polyester polymer into said pipe and crystallizing said molten polyester polymer to a degree of crystallinity of at least 30% in said pipe in 15 minutes or less.  
   
   
       116 . The process of  claim 115 , comprising crystallizing in 8 minutes or less.  
   
   
       117 . The process of  claim 109 , wherein the pipe is devoid of mechanically rotating paddles, in-line mixers, weirs, or baffles.  
   
   
       118 . The process of  claim 109 , wherein the liquid flow velocity within the pipe ranges from 1 ft/s to 8 ft/s.  
   
   
       119 . The process of  claim 109 , wherein the molten polyester polymer has an It.V. of at least 0.70 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       120 . The process of  claim 109 , wherein the molten polyester polymer has an It.V. of at least 0.75 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       121 - 126 . (canceled)  
   
   
       127 . The process of  claim 62 , wherein the molten polyester polymer has an It.V. of at least 0.70 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       128 . The process of  claim 127 , wherein the molten polyester polymer has an It.V. of at least 0.75 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       129 . The process of  claim 67 , wherein the molten polyester polymer has an It.V. of at least 0.70 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       130 . The process of  claim 129 , wherein the molten polyester polymer has an It.V. of at least 0.75 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       131 . The process of  claim 81 , wherein the molten polyester polymer has an It.V. of at least 0.70 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.  
   
   
       132 . The process of  claim 131 , wherein the molten polyester polymer has an It.V. of at least 0.75 dL/g when measured at 25° C. in a 60/40 wt/wt phenol/tetrachloroethane solvent at a polymer concentration of 0.50 g/100 ml.