Composition for maintaining good color when thermally treating polyester-polyamide blends

Abstract

A polymer composition and wall of a container made from such composition is set forth comprising a polyamide and polyester and a sufficient amount of an interfacial tension reducing agent such that the polyamide domains stretch disproportionately to the amount of stretch experienced by the polyester both with and without a cobalt salt.

I claim: 
     
         1 . A process for making a wall of a container comprising the steps of:
 A) making a crystallizable polyester in the presence of a di-ethylene glycol suppressant in the absence of a cobalt salt wherein the crystallizable polyester comprises acid units and glycol units; at least 85% of the polyester acid units of the crystallizable polyester are derived from terephthalic acid or the dimethyl ester of terephthalic acid; and at least a portion of the acid units, at least a portion of the glycol units, or at least a portion of both the acid units and the glycol units of the crystallizable polyester are an interfacial tension reducing agent consisting of a metal sulfonate;   B) forming a compartmentalized pellet having a sheath comprising the crystallizable polyester and a core comprising a polyamide;   C) subjecting the compartmentalized pellet to a solid state polymerization;   D) injection molding the compartmentalized pellet to form a preform comprising dispersed particles of the polyamide wherein the dispersed particles of the polyamide have an average particle diameter less than 100 nm; and   E) forming the wall of the container from the preform.   
     
     
         2 . The process of  claim 1 , wherein the di-ethylene glycol suppressant is selected from the group consisting of sodium acetate and lithium acetate. 
     
     
         3 . The process of  claim 1 , wherein the polyamide comprises at least one reaction product selected from the group consisting of the reaction of amino caproic acid with itself, and the reaction product of A-D where A is a residue of dicarboxylic acid comprising adipic acid, isophthalic acid, terephthalic acid, 1,4 cyclohexanedicarboxylic acid, resorcinol dicarboxylic acid, or naphthalenedicarboxylic acid, or a mixture thereof, and D is a residue of a diamine comprising m-xylylene diamine, p-xylylene diamine, hexamethylene diamine, ethylene diamine, or 1,4 cyclohexanedimethylamine, or a mixture thereof. 
     
     
         4 . The process of  claim 2 , wherein the polyamide comprises at least one reaction product selected from the group consisting of the reaction of amino caproic acid with itself, and the reaction product of A-D where A is a residue of dicarboxylic acid comprising adipic acid, isophthalic acid, terephthalic acid, 1,4 cyclohexanedicarboxylic acid, resorcinol dicarboxylic acid, or naphthalenedicarboxylic acid, or a mixture thereof, and D is a residue of a diamine comprising m-xylylene diamine, p-xylylene diamine, hexamethylene diamine, ethylene diamine, or 1,4 cyclohexanedimethylamine, or a mixture thereof. 
     
     
         5 . The process of  claim 1 , wherein the interfacial tension reducing agent is lithium sulfoisophthalate or sodium sulfoisophthalate. 
     
     
         6 . The process of  claim 5 , wherein the interfacial tension reducing agent is present at a level within the range of 0.1 and 2.0 mole percent based upon the moles of acid units or glycol units in the polyester. 
     
     
         7 . The process of  claim 6 , wherein the interfacial tension reducing agent is selected from the group consisting of functionalized lithium sulfonates, non-functionalized lithium sulfonates, functionalized sodium sulfonates and non-functionalized sodium sulfonates. 
     
     
         8 . The process of  claim 2 , wherein the interfacial tension reducing agent is lithium sulfoisophthalate or sodium sulfoisophthalate. 
     
     
         9 . The process of  claim 8 , wherein the interfacial tension reducing agent is present at a level within the range of 0.1 and 2.0 mole percent based upon the moles of acid units or glycol units in the polyester. 
     
     
         10 . The process of  claim 9 , wherein the interfacial tension reducing agent is selected from the group consisting of functionalized lithium sulfonates, non-functionalized lithium sulfonates, functionalized sodium sulfonates and non-functionalized sodium sulfonates. 
     
     
         11 . The process of  claim 3 , wherein the interfacial tension reducing agent is lithium sulfoisophthalate or sodium sulfoisophthalate. 
     
     
         12 . The process of  claim 11 , wherein the interfacial tension reducing agent is present at a level within the range of 0.1 and 2.0 mole percent based upon the moles of acid units or glycol units in the polyester. 
     
     
         13 . The process of  claim 12 , wherein the interfacial tension reducing agent is selected from the group consisting of functionalized lithium sulfonates, non-functionalized lithium sulfonates, functionalized sodium sulfonates and non-functionalized sodium sulfonates. 
     
     
         14 . The process of  claim 4 , wherein the interfacial tension reducing agent is lithium sulfoisophthalate or sodium sulfoisophthalate. 
     
     
         15 . The process of  claim 14 , wherein the interfacial tension reducing agent is present at a level within the range of 0.1 and 2.0 mole percent based upon the moles of acid units or glycol units in the polyester. 
     
     
         16 . The process of  claim 15 , wherein the interfacial tension reducing agent is selected from the group consisting of functionalized lithium sulfonates, non-functionalized lithium sulfonates, functionalized sodium sulfonates and non-functionalized sodium sulfonates.