Structural effects of glycol and benzenedicarboxylate units on the adhesion of water‐soluble polyester sizes to polyester fibers

Abstract

The adhesion of water‐soluble polyester (WSP) sizes to polyester fibers was investigated to reveal the relation between the functions of glycol and benzenedicarboxylate units in WSP macromolecules and the adhesion in order to improve the performance of WSP in warp sizing. Serial WSPs with the variation in both glycol and benzenedicarboxylate structures were synthesized through a two‐step reaction: transesterification and polycondensation. The adhesion was evaluated in terms of tensile strength and work‐to‐break using a slightly sized polyester roving method. The adhesion depended markedly on the structures of glycol and benzenedicarboxylate units. The decrease in the length of glycol unit enhanced the adhesion. With the increase in the amount of dimethyl isophthalate‐5‐sodium sulfonate (SIPM), the adhesion initially increased and then decreased while the amount of dimethyl isophthalate (DMI) appreciably affected the adhesion. Suitable monomers for the preparation of the sizes were ethylene glycol, dimethyl terephthalate (DMT), DMI, and SIPM. To achieve maximum adhesion, the proportion of benzenedicarboxylate monomers in molar ratio should be about 64(DMT)/11(DMI)/25(SIPM). The adhesion of the WSP thus produced to polyester fibers is similar to that of polyacrylates, but better than that of PVA.