Oxazolidines as curing agent for polyurethane adhesives
In a study, Chinese researchers have investigated the properties of oxazolidines as latent curing agents for single-component polyurethane adhesives.
Four oxazolidine compounds Ox1 to Ox4 were prepared. Their structures were characterised using Fourier transform infrared spectra, 1H-NMR, 13C-NMR, and ESI-MS.
Number of bubbles decreased
The kinetics research suggested that the hydrolysis of oxazolidine followed the first-order reaction. The gap of the ground energies between the open- and closed-ring was calculated using Gaussian software, which indicated that the stability of the open-ring system of OX1 was the best. Then, the obtained oxazolidines were applied to single-component polyurethane (SPU) and filler CaCO3 was added. The results show that the pore size and the number of bubbles produced in the SPU decreased with the increase of the rate of hydrolysis of the added oxazolidine, and the bondability of the polyurethane was better. With the increase of CaCO3 content, the polyurethane surface became smoother and the bond strength was stronger.
The study is published in: Journal of Applied Polymer Science, Volume 135, Issue 4, January 15, 2018
