PETG Pellets: Dimethyl Terephthalate with Ethylene Glycol and CHDM

PETG is PET in which part of the ethylene glycol is replaced by CHDM, which keeps the plastic clear and amorphous. Eastman's patent US 7,026,027 describes PETG 6763 as terephthalate with about 69 mol % ethylene glycol and 31 mol % CHDM, but gives no recipe for it. This blueprint is our own combination: that composition, made by the same patent's pilot-plant process (Example 12, written for a CHDM/neopentyl glycol copolyester), with ethylene glycol in place of neopentyl glycol as in Kibler's 1959 Eastman patent. The charge weights are our arithmetic. The picture: our diagram.