POLYESTER COMPOSITIONS COMPRISING TETRAMETHYL CYCLOBUTANEDIOL AND 1,4-CYCLOHEXANEDIMETHANOL HAVING AN IMPROVED CATALYST SYSTEM COMPRISING TITANIUM AND ZINC

This invention relates to a polyester composition comprising: (1) at least one polyester which comprises: (a) a dicarboxylic acid component comprising: (i) about 70 to about 100 mole % residues of terephthalic acid or esters thereof; (ii) about 0 to about 30 mole % of aromatic and/or aliphatic dicarboxylic acid residues having up to 20 carbon atoms; (b) a glycol component comprising: (i) about 10 to about 50 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; (ii) about 50 to about 90 mole % residues of modifying glycols; wherein the total mole % of the dicarboxylic acid component is 100 mole %, wherein the total mole % of the diol component is 100 mole %; and (2) residues of a catalyst system comprising lithium atoms, aluminum atoms, and, optionally, less than 30 ppm, or less than 20 ppm, or less than 10 ppm, or less than 5 ppm, or from 0 to 30 ppm, or from 0 to 20 ppm, or from 0 to 10 ppm, or 0 ppm of tin atoms, relative to the mass of final polyester being prepared.