| 초록 |
Waterborne polyurethane dispersions (WPUD) were prepared with polycarbonate-diols, 4,4’-methylenebis(cyclohexyl isocyanate), dimethyol propionic acid, and dibutyltin dilaurate catalyst. Conventional acetone process was used to synthesize the WPUDs. We determined the storage stability of the synthesized WPUDs whose physical properties, such as viscosity, particle size, molecular weight, and the content of hard- and soft-segment, were controlled by the molecular weight of polycarbonate-diols (MW = 500, 1000, and 2000 g/mol), the NCO index(=[NCO]/[OH] ratio or eqNCO/eqOH) 1.17 ~ 1.70, and the type of chain extender (1,4-butanediol and ethylene diamine). The storage stability was determined by measuring the variation of the viscosity, the particle size, and phase separation of the WPUDs with time at ambient temperature and ~5 ºC ( 1.0 ºC) |
