Preparation and optimization of WPU dispersion from polyether/polyester polyols for film and coating applications

• Published in: Journal of the Taiwan Institute of Chemical Engineers 2023-04, Vol.145, p.104832, Article 104832
• Main Authors: Liao, Yi-Han, Chen, Yi-Chun
• Format: Article
• Language: English
• Subjects: Castor oil; Cleaner process; Colloidal stability, Pre-polymerization, Waterborne polyurethane
• ISSN: 1876-1070; 1876-1089
• DOI: 10.1016/j.jtice.2023.104832

•The first case of pre-polymerization process without a DBTDL catalyst and ketones to synthesize castor oil-based WPU.•WPU dispersion exhibits excellent shelf-life stability for 6 months.•PTMG/castor oil molar ratio of 1/1 can improve the thermal and mechanical properties significantly.•WPU film and coating reveals high water resistance and chemical stability. Castor oil and polytetramethylene ether glycol (PTMG) are used as polyester and polyether polyols. The waterborne polyurethane (WPU) resin is synthesized from polyether/polyester polyols following a ketone and catalyst-free pre-polymerization process. WPU resins are prepared from PTMG/castor oil with various hydroxyl molar ratios, such as 1/0, 3/1, 1/1, 1/3, and 0/1. The results indicate that the WPU dispersions has a long shelf-life, high colloidal stability, and narrow distribution of molecular size. The addition of castor oil can increase the proportion of the cross-linking density, hard segments and hydrogen bonds of the WPU molecular chain. The addition of PTMG/castor oil increases from the molar ratio 1/0 to 1/1, the tensile strength of WPU film increases from 17.1 MPa to 25.6 MPa; the T5% increases from 250°C to 262°C; the water swelling ratio at 24 h decreases from 33.2 g/g to 19.4 g/g. The results indicate the using PTMG/castor oil can improve the mechanical strength, water resistance, and thermal stability of WPU film. The WPU could be applied to wood coatings with high properties. This study provides a cleaner process for optimizing the performance of WPU resin, which can replace conventional ketone- and organotin-based films and coatings. [Display omitted]