Polyester compositions for hot-fill containers

Abstract

Disclosed is a polyester composition comprising: I. a polyester consisting essentially of (i) diacid residues consisting essentially of terephthalic residues; and (ii) diol residues consisting essentially of about 92 to about 98 mole percent ethylene glycol residues, about 1 to about 4 mole percent diethylene glycol (DEG) residues, and about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues; and having an inherent viscosity (IhV) which satisfies the equations IhV−X−Y=0.74 to 0.80, wherein X is the mole fraction of CHDM and Y is the mole fraction of DEG; and II. at least one reheat enhancing aid in an amount sufficient to provide between about 5 and about 25% reheat improvement. Also disclosed are heat set containers suitable for packaging hot-filled liquids and processes for the manufacture of such heat set containers.

We claim:  
     
         1 . A polyester composition capable of producing a heat-set container comprising: 
 I. a polyester consisting essentially of: 
 (i) diacid residues consisting essentially of terephthalic residues; and  
 (ii) diol residues consisting essentially of ethylene glycol residues, about 1 to about 4 mole percent diethylene glycol (DEG) residues, and about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues; having an inherent viscosity (IhV, in dl/g) which satisfies the equations IhV−X−Y=0.74 to 0.80, wherein X is the mole fraction, expressed as a decimal, of CHDM and Y is the mole fraction, expressed as a decimal, of DEG; and  
   II. at least one reheat enhancing aid in an amount sufficient to provide between about 5 and about 35% reheat improvement; wherein said heat-set container exhibits less shrinkage when hot filled if compared to containers produced from other polyester compositions.    
     
     
         2 . The composition of  claim 1  wherein polyester component I consists essentially of: 
 (i) diacid residues consisting essentially of terephthalic residues; and  
 (ii) diol residues consisting essentially of about 94.5 to about 97.5 mole percent ethylene glycol residues, about 1.5 to about 3 mole percent DEG residues, and about 1 to about 2.5 mole percent CHDM residues;  
 and has an inherent viscosity (IhV, in dl/g) which satisfies the equations IhV−X−Y=0.76 to 0.80, wherein X is the mole fraction of CHDM and Y is the mole fraction of DEG; wherein said heat-set container exhibits less shrinkage when hot filled if compared to containers produced from polyester compositions comprising diol residues outside the range of about 1 to about 4 mole percent diethylene glycol (DEG) residues, and outside the range of about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues.  
 
     
     
         3 . The composition of  claim 1  or  2  wherein said reheat enhancing aid is selected from the group consisting of black and gray body absorbers and near infrared absorbing dyes.  
     
     
         4 . The composition of  claim 3  wherein said reheat enhancing aid is present in an amount of about 5 to about 150 ppm.  
     
     
         5 . The composition of  claim 4  wherein said reheat enhancing aid is present in an amount of about 10 to about 100 ppm.  
     
     
         6 . The composition of  claim 1  wherein said reheat enhancing aid is selected from the group consisting of carbon black, iron oxide, antimony, tin, copper, silver, gold, palladium, platinum or a mixture thereof.  
     
     
         7 . The composition of  claim 1  wherein said reheat enhancing aid is selected from the group consisting of carbon black, black iron oxide and antimony metal.  
     
     
         8 . A polyester composition comprising: 
 I. a polyester consisting essentially of: 
 (i) diacid residues consisting essentially of terephthalic residues; and  
 (ii) diol residues consisting essentially of about 94.5 to about 97.5 mole percent ethylene glycol residues, about 1.5 to about 3 mole percent diethylene glycol (DEG) residues, and about 1 to about 2.5 mole percent 1,4-cyclohexanedimethanol (CHDM) residues;  
 and has an inherent viscosity (IhV, in dl/g) which satisfies the equations IhV−X−Y=0.76 to 0.80, wherein X is the mole fraction of CHDM and Y is the mole fraction of DEG; and  
   II. about 5 to about 150 ppm of at least one reheat enhancing aid selected from carbon black, black iron oxide and antimony metal; wherein said heat-set container exhibits less shrinkage when hot filled if compared to containers produced from polyester compositions comprising diol residues outside the range of about 1 to about 4 mole percent diethylene glycol (DEG) residues, and outside the range of about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues.    
     
     
         9 . The composition of  claim 1  further comprising at least one UV absorbing compound which is thermally stable at polyester processing temperatures and provides less than 20% transmittance of UV light having a wavelength of 370 nm through a bottle wall 12 mils thick.  
     
     
         10 . The composition of  claim 9  wherein said UV absorbing compound has formula I:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R is hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl or alkenyl;  
 R 1  is hydrogen, or a group such as alkyl, aryl, or cycloalky, all of which groups may be substituted;  
 R 2  is any radical selected from the group consisting of hydrogen, alkyl, substituted alkyl, allyl, cycloalkyl or aryl;  
 R 3  is hydrogen or 1-3 substitutents selected from alkyl, substituted alkyl, alkoxy, substituted alkoxy and halogen, and  
 P is cyano, or a group such as carbamyl, aryl, alkylsulfonyl, arylsufonyl, heterocyclic, alkanoyl, or aroyl, all of which groups may be substituted.  
 
     
     
         11 . The composition of  claim 10  wherein R 2  is hydrogen, alkyl and hydroxyalkyl; R is selected from hydrogen or an alkyl linking group; and P is cyano.  
     
     
         12 . The composition of  claim 10  where said UV absorbing compound comprises at least two compounds of formula I.  
     
     
         13 . The composition of  claim 10  wherein said UV absorbing compound is present in an amount between 1 to about 5000 ppm by weight.  
     
     
         14 . The composition of  claim 10  wherein said UV absorbing compound is present in an amount between about 2 ppm to about 1,500 ppm by weight.  
     
     
         15 . The composition of  claim 10  wherein said UV absorbing compound is present in an amount between about 10 and about 700 ppm by weight.  
     
     
         16 . A heat-set container comprising: 
 I. a polyester consisting essentially of: 
 (i) diacid residues consisting essentially of terephthalic residues; and  
 (ii) diol residues consisting essentially of ethylene glycol residues, about 1 to about 4 mole percent diethylene glycol (DEG) residues, and about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues;  
 and having an inherent viscosity (IhV, in dl/g) which satisfies the equations IhV−X−Y=0.74 to 0.80, wherein X is the mole fraction, expressed as a decimal, of CHDM and Y is the mole fraction, expressed as a decimal, of DEG; and  
   II. at least one reheat enhancing aid in an amount sufficient to provide between about 5 and about 35% reheat improvement; wherein said heat-set container exhibits less shrinkage when hot filled if compared to containers produced from polyester compositions comprising diol residues outside the range of about 1 to about 4 mole percent diethylene glycol (DEG) residues, and outside the range of about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues.    
     
     
         17 . The heat set container of  claim 16  wherein polyester component consists essentially of: 
 (i) diacid residues consisting essentially of terephthalic residues; and  
 (ii) diol residues consisting essentially of about 94.5 to about 97.5 mole percent ethylene glycol residues, about 1.5 to about 3 mole percent DEG residues, and about 1 to about 2.5 mole percent CHDM residues; 
 and has an inherent viscosity (IhV, in dl/g) which satisfies the equations IhV−X−Y=0.76 to 0.80, wherein X is the mole fraction of CHDM and Y is the mole fraction of DEG; wherein said heat-set container exhibits less shrinkage when hot filled if compared to containers produced from polyester compositions comprising diol residues outside the range of about 1 to about 4 mole percent diethylene glycol (DEG) residues, and outside the range of about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues.  
 
 
     
     
         18 . The heat set container of  claim 17  wherein said reheat enhancing aid is selected from the group consisting of black and gray body absorbers and near infrared absorbing dyes.  
     
     
         19 . The heat set container of  claim 18  wherein said reheat enhancing aid is present in an amount of about 5 to about 150 ppm.  
     
     
         20 . The heat set container of  claim 4  wherein said reheat enhancing aid is present in an amount of about 10 to about 100 ppm.  
     
     
         21 . The heat set container of  claim 16  wherein said reheat enhancing aid is selected from the group consisting of carbon black, iron oxide, antimony, tin, copper, silver, gold, palladium, platinum or a mixture thereof.  
     
     
         22 . The heat set container of  claim 1  wherein said reheat enhancing aid is selected from the group consisting of carbon black, black iron oxide and antimony metal.  
     
     
         23 . A heat set container comprising: 
 I. a polyester consisting essentially of: 
 (i) diacid residues consisting essentially of terephthalic residues; and  
 (ii) diol residues consisting essentially of about 94.5 to about 97.5 mole percent ethylene glycol residues, about 1.5 to about 3 mole percent diethylene glycol (DEG) residues, and about 1 to about 2.5 mole percent 1,4-cyclohexanedimethanol (CHDM) residues;  
 and has an inherent viscosity (IhV, in dl/g) which satisfies the equations IhV−X−Y=0.76 to 0.80, wherein X is the mole fraction of CHDM and Y is the mole fraction of DEG; and p 1  II. about 1 to about 300 ppm of at least one reheat enhancing aid; wherein said heat-set container exhibits less shrinkage when hot filled if compared to containers produced from polyester compositions comprising diol residues outside the range of about 1 to about 4 mole percent diethylene glycol (DEG) residues, and outside the range of about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues.  
   
     
     
         24 . The heat set container of  claim 16  further comprising at least one UV absorbing compound which is thermally stable at polyester processing temperatures and provides less than 20% transmittance of UV light having a wavelength of 370 nm through a bottle wall 12 mils thick.  
     
     
         25 . The heat set container of  claim 16  wherein said UV absorbing compound has formula I:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R is hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl or alkenyl;  
 R 1  is hydrogen, or a group such as alkyl, aryl, or cycloalky, all of which groups may be substituted;  
 R 2  is any radical selected from the group consisting of hydrogen, alkyl, substituted alkyl, allyl, cycloalkyl or aryl;  
 R 3  is hydrogen or 1-3 substitutents selected from alkyl, substituted alkyl, alkoxy, substituted alkoxy and halogen, and  
 P is cyano, or a group such as carbamyl, aryl, alkylsulfonyl, arylsufonyl, heterocyclic, alkanoyl, or aroyl, all of which groups may be substituted.  
 
     
     
         26 . The heat set container of  claim 25  wherein R 2  is hydrogen, alkyl and hydroxyalkyl; R is selected from hydrogen or an alkyl linking group; and P is cyano.  
     
     
         27 . The heat set container of  claim 25  where said UV absorbing compound comprises at least two compounds of formula I.  
     
     
         28 . The heat set container of  claim 25  wherein said UV absorbing compound is present in an amount between 1 to about 5000 ppm by weight.  
     
     
         29 . The heat set container of  claim 10  wherein said UV absorbing compound is present in an amount between about 2 ppm to about 1,500 ppm by weight.  
     
     
         30 . The heat set container of  claim 25  wherein said UV absorbing compound is present in an amount between about 10 and about 700 ppm by weight.  
     
     
         31 . The heat set container according to  claim 16 ,  17 ,  23 ,  24  or  25  wherein said container is a bottle.  
     
     
         32 . A process for forming a heat-set container which comprises the steps of: 
 (1) injection molding the polyester composition of  claim 1  to form a container perform;    (2) reheating or temperature conditioning the perform; and    (3) stretch blow molding the preform of step (2) into a mold heated at a temperature of about 90 to 160° C.; wherein said container exhibits less shrinkage when hot filled if compared to containers blown with compositions comprising diol residues outside said range.    
     
     
         33 . The process of  claim 16  wherein step (3) comprises stretch blow molding the preform of step (2) into a mold heated at a temperature of about 100 to about 140° C.  
     
     
         34 . A heat set container formed from the composition of  claim 1 .  
     
     
         35 . A heat set container formed from the composition of  claim 5 .  
     
     
         36 . A process for forming a heat-set container which comprises the steps of: 
 (1) injection molding the polyester composition of  claim 8  to form a container perform;    (2) reheating the preform; and    (3) stretch blow molding the preform of step (2) into a mold heated at a temperature of about 100 to about 140° C.; wherein said heat-set container exhibits less shrinkage when hot filled if compared to containers produced from polyester compositions comprising diol residues outside the range of about 1 to about 4 mole percent diethylene glycol (DEG) residues, and outside the range of about 1 to about 4 mole percent 1,4-cyclohexanedimethanol (CHDM) residues.