Manual applied polyurethane-urea: High performance coating based on CO2-based polyol and polyaspartic ester

Abstract

Brushable polyurea based on slow reactive process was prepared by simple, mild and solvent-free method. Firstly, polyurethane prepolymer was synthesized from poly (propylene carbonate) diol (PPCD, copolymer of propylene oxide/CO2) and 4,4′-dicylocyhexylmethane diisocyanate (HMDI). Polyurethane-urea (PPCD–PUU) was then obtained by the chain extension of prepolymer with polyaspartic ester (PAE). The mechanical properties of PPCD–PUU were optimized by adjusting the content of –NCO in the prepolymer and the ratio of prepolymer to PAE. The mechanical strength, thermal resistance, solvent resistance and hydrolysis resistance of PPCD–PUU were compared with those of PUUs derived from polypropylene glycol and poly-caprolactone diol. The results showed that the comprehensive mechanical properties of PPCD–PUU were balanced when the R value was 1.15 and the content of –NCO was 8 %. The tensile strength was 20.5 MPa, the elongation at break was 352 %, and the Young's modulus was 168.2 MPa. Especially, after soaking in 10 % H2SO4 aqueous solution, 10 % NaOH aqueous solution and 10 % NaCl aqueous solution for 24 h, the tensile properties were basically unchanged. Manual applied polyurethane-urea based on commercial PPCD has broad application prospects because it avoids the use of expensive spraying equipment.