Patent ID: 8586701

Claim:
A process for the preparation of a copolyester, comprising: reacting a diester composition comprising dimethyl terephthalate with a first diol component comprising 2,2,4,4-tetramethyl-1,3-cyclobutanediol and a second diol component comprising 1,4-cyclohexanedimethanol, said reaction comprising (i) reacting said first diol component comprising about 100 mole percent of said 2,2,4,4-tetramethyl-1,3-cyclobutanediol, based on the total moles of 2,2,4,4-tetramethyl-1,3-cyclobutanediol in said first and second diol components, and about 30 to about 80 mole percent of said 1,4-cyclohexanedimethanol, based on the total moles of 1,4-cyclohexanedimethanol in said first and second diol components, with said diester composition to form a polyester oligomer at a conversion of said 2,2,4,4-tetramethyl-1,3-cyclobutanediol of at least 50 mole percent, based on the total moles of said 2,2,4,4-tetramethyl-1,3-cyclobutanediol in said first and second diol components; (ii) reacting said second diol component comprising about 20 to about 70 mole percent of said 1,4-cyclohexanedimethanol based on the total moles of 1,4-cyclohexanedimethanol in said first and second diol components, with said polyester oligomer of step (i) to form a modified polyester oligomer; and (iii) heating said modified polyester oligomer to form a thermoplastic, random copolyester having an inherent viscosity of about 0.4 dL/g to about 1.0 dL/g; wherein the molar ratio of all diols in said first and second diol components to all diesters in said diester composition is about 1.1 to about 1.5.