Ultra-high iv polyester for extrusion blow molding and method for its production

Abstract

An ultra-high IV polyester suitable for high melt strength end-uses, such as injection blow molding, pipe extrusion, profile extrusion, and extrusion blow molding, is provided, having IV of greater than 0.9; and a process for its production having high IV lift rate during SSP processing.

1 . A method for producing an ultra-high intrinsic viscosity (IV) polyester resin having a final IV (IV f ) of at least 0.9 dL/g, comprising:
 solid-state polymerizing a polyester starting material having a starting IV (IV st ) meeting the following relationship:
   0.65 dL/g< IV   st <0.9 dL/g; 
   wherein the polyester starting material is a polyethylene terephthalate polymer, optionally containing one or more comonomers in amounts up to 30 mol %, wherein the polyester starting material has been prepared by melt polymerization up to the IV st  with no more than 0.05 dL/g of IV lift due to solid-state polymerization, and wherein the polyester starting material is in solid form as a resin particle having been subjected to latent heat crystallization upon formation of the resin particle, and having a variation of IV of no more than 0.05 dL/g across any dimension of the resin particle.   
     
     
         2 . The method of  claim 1 , wherein the IV f  of the ultra-high IV polyester is greater than 1.0 dL/g. 
     
     
         3 . The method of  claim 2 , wherein the IV f  of the ultra-high IV polyester is greater than 1.1 dL/g. 
     
     
         4 . The method of  claim 3 , wherein the IV f  of the ultra-high IV polyester is greater than 1.2 dL/g. 
     
     
         5 . The method of  claim 4 , wherein the IV f  of the ultra-high IV polyester is greater than 1.3 dL/g. 
     
     
         6 . The method of  claim 1 , wherein the IV st  of the polyester starting material is from 0.70 to 0.85 dL/g. 
     
     
         7 . The method of  claim 6 , wherein the IV st  of the polyester starting material is from 0.72 to 0.82 dL/g. 
     
     
         8 . The method of  claim 1 , wherein the resin particle of the polyester starting material has a variation of IV of no more than 0.03 dL/g across any dimension of the resin particle. 
     
     
         9 . The method of  claim 1 , wherein the solid-state polymerizing is carried out at a temperature of 190-230° C. 
     
     
         10 . The method of  claim 9 , wherein the solid-state polymerizing is carried out at a temperature of 200-225° C. 
     
     
         11 . The method of  claim 10 , wherein the solid-state polymerizing is carried out at a temperature of 210-220° C. 
     
     
         12 . The method of  claim 11 , wherein the solid-state polymerizing is carried out at a temperature of about 215° C. 
     
     
         13 . The method of  claim 1 , wherein the one or more comonomers are selected from the group consisting of diethylene glycol (DEG), cyclohexane dimethanol (CHDM), 1,3-propane diol, isophthalic acid (IPA). 
     
     
         14 . The method of  claim 13 , wherein the one or more comonomers are both DEG and IPA. 
     
     
         15 . The method of  claim 14 , wherein the IPA is present in an amount of from 2-6 mol %. 
     
     
         16 . The method of  claim 14 , wherein the IPA is present in an amount of from 8-25 mol %. 
     
     
         17 . The method of  claim 14 , wherein the DEG is present in an amount of 2 mol % or less. 
     
     
         18 . An ultra-high IV polyester resin prepared by the method of  claim 1 . 
     
     
         19 . A molded article prepared from the ultra-high IV polyester resin of  claim 18 . 
     
     
         20 . The molded article of  claim 19 , wherein the molded article is prepared by extrusion blow molding. 
     
     
         21 . The molded article of  claim 19 , wherein the molded article is prepared by thermoforming. 
     
     
         22 . The molded article of  claim 19 , wherein the molded article contains no bisphenol A. 
     
     
         23 . The molded article of  claim 19 , wherein the molded article is selected from the group consisting of bottles, trays, cups, glasses, other containers and extruded hollow articles. 
     
     
         24 . A parison prepared from the ultra-high IV polyester resin of  claim 18 , wherein the parison is suitable for use in a molding process selected from the group consisting of stretch blow molding, pipe extrusion, profile extrusion, and extrusion blow molding.