Cationic CO2-based Waterborne Polyurethane with High Solid Content and Excellent Ageing Resistance

High solid content CO2-based cationic waterborne polyurethanes (CWPUs) were prepared using CO2-polyols as soft segment and N-methyl diethanolamine (MDEA) as hydrophilic group. The resulting stable aqueous dispersion displayed a high solid content of 52% with a low MDEA loading of 3.52 wt%. This novel structural CWPU can provide excellent adhesive strength, whose T-peel strength could reach 173.48 N/5cm, 20% higher than that of ester-based cationic waterborne polyurethane (87.55 N/5cm). The CO2-based CWPU film showed only 2 wt% swelling percentage after 240 min immersion in water, and no change was observed during its immersion in 5 wt% sodium hydroxide solution. The tensile strength of CO2-WPUs dropped slowly to 91.2% after 480 min immersion in a 5 wt% sodium hydroxide solution, whereas that of ester-based CWPUs dropped quickly to 32% after 240 min and their mechanical properties were lost after 360 min immersion. Meanwhile, the retention of the tensile strength of the CO2-CWPUs was 81.5% even after 720 min immersion in 10 wt% H2O2 solution, while it was only ca. 38% for the ester-based CWPUs. These results indicated that the cationic CO2-based CWPU may be promising waterborne adhesive with outstanding ageing resistance due to its synergistic effect from carbonate and ether groups of CO2-polyol structure.

Automated summary

High solid content CO2-based cationic waterborne polyurethanes (CWPUs) prepared using CO2-polyols and MDEA exhibited excellent adhesive strength and aging resistance.