Two new triazine-based dyes have been prepared with the following general formula:
in which R = HNCH2CH2OH or NHCH2COOH. As a result of the presence of suitable functional groups, these compounds can be incorporated in the polycondensation process which gives colored polyethylene glycol terephthalates (PEGT). By means of a spectrophotometric investigation, it has been demonstrated that the dye does not change its structure under high temperature or its incorporation in the polymer chain. A colorimetric study has been made of the dye content of the polymer as related to the quantity initially taken for the reaction. It has been shown that the inclusion of the dye in the polycondensation process does not affect notably the molecular weight, melting point, and the polydispersion of the polymers. Intensive coloration can be obtained with very low concentrations of the dye, 0.1–0.5%. By comparing the infrared spectra of the polymer and the pure dyes, the dyes have been demonstrated to be bound to the polymer molecule. Since the dye is part of the basic chain of PEGT, the polymers retain their color after repeated reprecipitation. The proposed method can be used for the preparation of saturated polyesters of divers properties and persistent colors.