Polyester polymer and copolymer compositions containing particles of one or more transition metal compounds

A beverage bottle preform having improved reheat, comprising:

• a polyester polymer in which poly(ethylene terephthalate) residues comprise at least 90 wt. % of the polyester polymer;
• and
• particles of one or more transition metal compounds, randomly dispersed in the polyester polymer in an amount from about 0.5 ppm to about 1,000 ppm with respect to the total weight of the polyester composition, the transition metal compounds being binary compounds of a transition metal element selected from titanium, vanadium, zirconium, niobium, hafnium, and tantalum, and a non-metallic element selected from boron, carbon, and nitrogen,
• wherein the beverage bottle preform reheats in the presence of infrared energy to a higher temperature in a given time than would a beverage bottle preform having no such particles present, and
• wherein the beverage bottle preform has a b* value from about minus 0.8 to about plus 2.5, and a preform L* value of 70 or more.

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 particles of one or more transition metal compounds in the polymer in an amount from about 0.5 ppm to about 1,000 ppm with respect to the total weight of the polyester composition, the transition metal compounds being binary compounds of a transition metal element selected from titanium, vanadium, zirconium, niobium, hafnium, and tantalum, and a non-metallic element selected from boron, carbon, and nitrogen, wherein the particle addition step occurs before, during, or after any of the preceding steps.