Polyester polymer and copolymer compositions containing metallic titanium particles

Abstract

Polyester compositions are disclosed that include polyester polymers or copolymers having incorporated therein metallic titanium particles that improve the reheat properties of the compositions. Processes for making such compositions are also disclosed. The titanium particles may be incorporated in the polyester by melt compounding, or may be added at any stage of the polymerization, such as during the melt-phase of the polymerization. A range of particle sizes may be used, as well as a range of particle size distributions. The polyester compositions are suitable for use in packaging made from processes in which a reheat step is desirable.

1 . A process for producing a polyester composition, comprising:
 an esterification step comprising transesterifying a dicarboxylic acid diester with a diol, or directly esterifying a dicarboxylic acid with a diol, to obtain one or more of a polyester monomer or a polyester oligomer;   a polycondensation step comprising reacting the one or more of a polyester monomer or a polyester oligomer in a polycondensation reaction in the presence of a polycondensation catalyst to produce a polyester polymer having an It.V. from about 0.50 dL/g to about 1.1 dL/g;   a particulation step in which the molten polyester polymer is solidified into particles;   an optional solid-stating step in which the solid polymer is polymerized to an It.V. from about 0.70 dL/g to about 1.2 dL/g; and   a particle addition step comprising adding and dispersing metallic titanium particles to provide an amount from about 1 ppm to about 100 ppm by weight of the polymer, wherein the particle addition step occurs before, during, or after any of the preceding steps.   
     
     
         2 . The process according to  claim 1 , wherein the process further comprises a forming step, following the solid-stating step, the forming step comprising melting and extruding the resulting solid polymer to obtain a formed item having the metallic titanium particles dispersed therein. 
     
     
         3 . The process according to  claim 2 , wherein the particle addition step occurs during or after the solid-stating step and prior to the forming step. 
     
     
         4 . The process according to  claim 1 , wherein the particle addition step comprises adding the metallic titanium particles as a thermoplastic concentrate prior to or during the forming step, the thermoplastic concentrate comprising the metallic titanium particles in an amount from about 100 ppm to about 5,000 ppm, with respect to the weight of the thermoplastic concentrate. 
     
     
         5 . The process according to  claim 1 , wherein the metallic titanium particles have a median particle size from about 0.005 μm to about 100 μm. 
     
     
         6 . The process according to  claim 1 , wherein the particle addition step is carried out prior to or during the polycondensation step. 
     
     
         7 . The process according to  claim 1 , wherein the particle addition step is carried out prior to or during the particulation step. 
     
     
         8 . The process according to  claim 1 , wherein the particle addition step is carried out prior to or during the solid-stating step. 
     
     
         9 . The process according to  claim 2 , wherein the particle addition step is carried out prior to or during the forming step. 
     
     
         10 . The process according to  claim 1 , wherein the dicarboxylic acid comprises terephthalic acid. 
     
     
         11 . The process according to  claim 1 , wherein the dicarboxylic acid diester comprises dimethyl terephthalate. 
     
     
         12 . The process according to  claim 1 , wherein the diol comprises ethylene glycol. 
     
     
         13 . The process according to  claim 1 , wherein the dicarboxylic acid comprises naphthalene dicarboxylic acid. 
     
     
         14 . The process according to  claim 1 , wherein the dicarboxylic acid comprises an aromatic dicarboxylic acid. 
     
     
         15 . The process according to  claim 4 , wherein the thermoplastic concentrate comprises:
 metallic titanium particles, in an amount ranging from about 0.15 wt. % up to about 35 wt. % based on the weight of the thermoplastic concentrate; and   a thermoplastic polymer, in an amount of at least 65 wt. % based on the weight of the thermoplastic concentrate.   
     
     
         16 . The process according to  claim 15 , wherein the thermoplastic polymer comprises one or more of: a polyester, a polyolefin, or a polycarbonate.