Process to Make Polyesters With An Interfacial Tension Reducing Agent for Blending with Polyamides

Abstract

Process to Make Polyesters With An Interfacial Tension Reducing Agent for Blending with Polyamides A process to make an improved polymer-polyamide blend composition and wall of a container made from such composition is set forth comprising making a modified polyester with a sufficient amount of an interfacial tension reducing agent such that the polyamide domains are better dispersed into the polyester.

1 . A method for making an improved polyamide-polyester polymer blend, comprising: 
 reacting a terephthalate component and a diol component to form polyethylene terephthalate precursors;    thereafter reacting sulfonated organic compound with the polyethylene terephthalate precursors to yield modified polyethylene terephthalate precursors;    polymerizing the modified polyethylene terephthalate precursors to form polyamide-compatible polyethylene terephthalate polymers; and    blending polyamide polymers with the polyamide-compatible polyethylene terephthalate polymers to form a polyamide-polyester polymer blend.    
   
   
       2 . A method according to  claim 1 , wherein the step of reacting a terephthalate component and a diol component comprises reacting a terephthalate component and a diol component to form polyethylene terephthalate precursors having at least some comonomer substitution, but less than about 10 mole percent comonomer substitution.  
   
   
       3 . A method according to  claim 1 , wherein the step of reacting sulfonated organic compound with the polyethylene terephthalate precursors comprises initiating a reaction between the sulfonated organic compound and the polyethylene terephthalate precursors when the polyethylene terephthalate precursors have a carboxyl end group concentration of less than about 1000 microequivalents per gram.  
   
   
       4 . A method according to  claim 1 , wherein the step of polymerizing the modified polyethylene terephthalate precursors comprises polymerizing the modified polyethylene terephthalate precursors to form polyamide-compatible polyethylene terephthalate polymers comprising sulfonated organic compound substitution in an amount between about 0.1 and 2.0 mole percent.  
   
   
       5 . A method according to  claim 1 , wherein the step of polymerizing the modified polyethylene terephthalate precursors comprises polymerizing the modified polyethylene terephthalate precursors to form polyamide-compatible polyethylene terephthalate polymers comprising sulfonated organic compound substitution in an amount between about 0.2 and 1.0 mole percent.  
   
   
       6 . A method according to  claim 1 , wherein the step of polymerizing the modified polyethylene terephthalate precursors comprises: 
 polymerizing the modified polyethylene terephthalate precursors via melt phase polycondensation to form polyamide-compatible polyethylene terephthalate polymers; and    thereafter polymerizing the polyamide-compatible polyethylene terephthalate polymers via solid state polymerization, wherein the step of solid state polymerizing the polyamide-compatible polyethylene terephthalate polymers comprises solid state polymerizing the polyamide-compatible polyethylene terephthalate polymers to an intrinsic viscosity of between about 0.65 and 1.0 dL/g.    
   
   
       7 . A method according to  claim 1 , wherein each step, until the blending of the polyamide polymers with the polyamide-compatible polyethylene terephthalate polymers, is performed by a process selected from the group consisting of continuous, semi-continuous and batch processes.  
   
   
       8 . A method according to  claim 1 , wherein the sulfonated organic compound comprises a compound selected from the group consisting of mostly sulfonated aliphatic compounds, mostly sulfonated aromatic compounds, mostly esterified sulfonated aromatic compounds, organic sulfonic acids, neutralized organic sulfonic acids, mostly ionomeric sulfonated isophthalate derivatives, dimethyl sulfoisophthalates (DMSIP), and sulfoisophthalic acids (SIPA).  
   
   
       9 . A method according to  claim 1 , wherein the step of reacting sulfonated organic compound with the polyethylene terephthalate precursors comprises introducing the sulfonated organic compound into polyethylene terephthalate precursors having an average degree of polymerization between about 2 and 10.  
   
   
       10 . A method according to  claim 1 , wherein the step reacting sulfonated organic compound with the polyethylene terephthalate precursors comprises introducing the sulfonated organic compound into polyethylene terephthalate precursors having an average degree of polymerization between about 3 and 6.  
   
   
       11 . A method according to  claim 1 , wherein the step of reacting a terephthalate component and a diol component comprises reacting in an esterification reaction (i) a diacid component comprising terephthalic acid and (ii) a diol component comprising ethylene glycol.  
   
   
       12 . A method according to  claim 11 , wherein the step of reacting a terephthalate component and a diol component comprises reacting a diacid component that includes at least 95 mole percent terephthalic acid and a diol component that includes at least 95 mole percent ethylene glycol.  
   
   
       13 . A method according to  claim 12 , wherein the sulfonated organic compound is introduced to the polyethylene terephthalate precursors just prior to melt phase polycondensation.  
   
   
       14 . A method according to  claim 11 , wherein the step of reacting a terephthalate component and a diol component comprises reacting a diacid component and a diol component in the presence of a buffer in an amount sufficient to control the acidity of the sulfonated organic compound and thereby reduce diethylene glycol formation during the esterification reaction.  
   
   
       15 . A method according to  claim 14 , wherein the buffer is introduced to the esterification reaction prior to or concurrently with the initiation of the reaction between the sulfonated organic compound and the polyethylene terephthalate precursors.  
   
   
       16 . A method according to  claim 11 , wherein the sulfonated organic compound is introduced to the polyethylene terephthalate precursors after the completion of the esterification reaction.  
   
   
       17 . A method according to  claim 11 , wherein the step of reacting sulfonated organic compound with the polyethylene terephthalate precursors comprises initiating a reaction between the sulfonated organic compound and the polyethylene terephthalate precursors when the polyethylene terephthalate precursors have a carboxyl end group concentration of between about 300 and 900 microequivalents per gram.  
   
   
       18 . A method according to  claim 11 , wherein the step of reacting sulfonated organic compound with the polyethylene terephthalate precursors comprises initiating a reaction between the sulfonated organic compound and the polyethylene terephthalate precursors when the polyethylene terephthalate precursors have a carboxyl end group concentration of between about 400 and 800 microequivalents per gram.  
   
   
       19 . A method according to  claim 1 , wherein the step of polymerizing the modified polyethylene terephthalate precursors comprises: 
 polymerizing the modified polyethylene terephthalate precursors via melt phase polycondensation to form polyamide-compatible polyethylene terephthalate polymers; and    thereafter polymerizing the polyamide-compatible polyethylene terephthalate polymers via solid state polymerization to an intrinsic viscosity of between about 0.70 and 0.85 dL/g.    
   
   
       20 . A method according to  claim 1 , wherein the step of blending polyamide polymers with the polyamide-compatible polyethylene terephthalate polymers comprises blending between about 1 and 5 weight percent nylon-MXD6 polyamide polymers with at least 95 weight percent polyamide-compatible polyethylene terephthalate polymers comprising ionomeric sulfonated isophthalate derivatives in an amount between about 0.1 and 2.0 mole percent.