Methods for Making Polyester Resins Having Reduced Frictional Properties

Abstract

The invention is a method for the late introduction of inert particulate additives via a reactive carrier to achieve a polyester resin that is capable of being formed into low-haze, high-clarity bottles possessing reduced coefficient of friction. The invention is also a polyester resin that includes between about 20 and 200 ppm of an inert particulate additive, such as surface-modified talc or surface-modified calcium carbonate.

1 . A method for introducing surface-modified talc into polyethylene terephthalate, comprising: 
 forming polyethylene terephthalate polymers via melt phase polycondensation; and    thereafter introducing between about 20 and 200 ppm of surface-modified talc into the polyethylene terephthalate polymers via a reactive carrier having a molecular weight of less than about 10,000 g/mol.    
     
     
         2 . A method according to  claim 1 , wherein the surface-modified talc comprises organosilane-treated talc having an average particle size of less than about ten microns.  
     
     
         3 . A method according to  claim 1 , wherein the surface-modified talc has an average particle size of less than about two microns.  
     
     
         4 . A method according to  claim 1 , wherein the step of introducing surface-modified talc into the polyethylene terephthalate polymers comprises introducing between about 40 and 150 ppm of surface-modified talc.  
     
     
         5 . A method according to  claim 1 , wherein the step of introducing surface-modified talc into the polyethylene terephthalate polymers comprises introducing less than about 100 ppm of surface-modified talc.  
     
     
         6 . A method according to  claim 1 , wherein the reactive carrier has a molecular weight of more than about 300 g/mol.  
     
     
         7 . A method according to  claim 1 , wherein the reactive carrier is a liquid or slurry at near ambient temperatures.  
     
     
         8 . A method according to  claim 1 , wherein the reactive carrier possesses a carboxyl functional group, a hydroxyl functional group, or an amine functional group.  
     
     
         9 . A method according to  claim 1 , wherein the step of introducing surface-modified talc via a reactive carrier comprises introducing the reactive carrier into the polyethylene terephthalate polymers in quantities such that bulk properties of the polyethylene terephthalate polymers are not detrimentally affected.  
     
     
         10 . A method according to  claim 1 , wherein the step of introducing surface-modified talc via a reactive carrier comprises reacting the reactive carrier with the polyethylene terephthalate polymers.  
     
     
         11 . A method according to  claim 1 , wherein the reactive carrier is introduced into the polyethylene terephthalate polymers via an additive delivery system that does not employ an extruder to introduce the reactive carrier into the polyethylene terephthalate polymers.  
     
     
         12 . A method according to  claim 1 , further comprising forming the polyethylene terephthalate polymers into a preform.  
     
     
         13 . A method according to  claim 1 , further comprising forming the polyethylene terephthalate polymers into a container.  
     
     
         14 . A method for introducing talc into polyethylene terephthalate polymers, comprising: 
 polymerizing polyethylene terephthalate precursors via a continuous melt phase polycondensation process to form a polyester melt comprising polyethylene terephthalate polymers; and    thereafter introducing into the polyester melt formed during the continuous melt phase polycondensation process a reactive carrier having a molecular weight of between about 300 g/mol and 10,000 g/mol, the reactive carrier being the delivery vehicle for between about 20 and 200 ppm of talc.    
     
     
         15 . A method according to  claim 14 , wherein the talc has an average particle size of less than about ten microns.  
     
     
         16 . A method according to  claim 14 , wherein the talc comprises surface-modified talc having an average particle size of less than about two microns.  
     
     
         17 . A method according to  claim 14 , wherein the reactive carrier is the delivery vehicle for less than about 150 ppm of surface-modified talc.  
     
     
         18 . A method according to  claim 14 , further comprising, after the introduction of the reactive carrier and talc into the polyester melt, forming the polyethylene terephthalate polymers into a preform or a container.  
     
     
         19 . A method for introducing talc into polyethylene terephthalate polymers, comprising: 
 polymerizing polyethylene terephthalate precursors via a continuous melt phase polycondensation process to form a polyester melt comprising polyethylene terephthalate polymers having an intrinsic viscosity of at least about 0.45 dl/g;    thereafter introducing into the polyester melt formed during the continuous melt phase polycondensation process a reactive carrier having a molecular weight of between about 300 g/mol and 10,000 g/mol, the reactive carrier being the delivery vehicle for between about 20 and 200 ppm of talc; and    then continuing the melt phase polycondensation of the polyethylene terephthalate polymers.    
     
     
         20 . A method according to  claim 19 , wherein the talc has an average particle size of less than about ten microns.  
     
     
         21 . A method according to  claim 19 , wherein the talc has an average particle size of less than about two microns.  
     
     
         22 . A method according to  claim 19 , wherein the reactive carrier is the delivery vehicle for between about 40 and 150 ppm of talc.  
     
     
         23 . A method according to  claim 19 , further comprising, after the step of continuing melt phase polycondensation, forming the polyethylene terephthalate polymers into a preform or a container.