Patent ID: 7915374

Claim:
A process for producing a polyethylene terephthalate copolyester, comprising: esterifying a mixture of at least terephthalic acid, from 25 mole percent to 45 mole percent 1,4-cyclohexanedimethanol, and ethylene glycol, optionally in the presence of one or more alkaline earth metals or alkali metals, to form an oligomer; polycondensing the oligomer in the melt phase in the presence of aluminum and one or more alkaline earth metals or alkali metals, to obtain a copolyester having an intrinsic viscosity of at least 0.5 dL/g, as calculated from the inherent viscosity (Ih.V.) measured at 25° C. in 60/40 wt/wt phenol/tetrachloroethane; and thereafter adding to the copolyester a phosphorus-containing compound.