Catalytic Process Regulation of Low-Impurity PET Polyester and Its Application in Medical Sutures

Polyethylene terephthalate (PET), recognized for its excellent mechanical properties and chemical stability, holds significant potential in biomedical applications. However, the antimony-based catalysts commonly used in conventional PET synthesis result in metal residues and uncontrolled byproduct formation, limiting their application in high-end medical suture materials. In this study, a titanium-based catalytic system, TZC, characterized by high catalytic activity (TOF = 1723 h–1) and low loading (100 ppm), was developed through catalyst structure design to minimize metal residues during polymerization. Based on the highly active titanium–zinc bimetallic synergistic catalysis, PET exhibited a significantly reduced reaction temperature (265 °C) and shortened reaction time, effectively controlling thermal degradation and side reactions. PET pellets showed a b* value of approximately 8, while PET-500 L exhibited a DEG content of 0.77 wt %. Furthermore, PET yarns were fabricated from the resulting high-purity PET pellets by melt spinning. The resulting PET pellets exhibited low residual metal levels (≤10 ppm for the analyzed metals), supporting their potential for medical material applications. The resulting yarns and braided sutures showed favorable mechanical performance and preliminary biocompatibility for medical suture applications. This study provides experimental evidence and technical guidelines for the preparation of raw materials and the optimization of processing routes for medical PET sutures.