Abstract:

A kind of two-component waterborne polyurethane(2K-WPU)was prepared by mixing HDI biuret and water.soluble acrylic resin.a dilution with water being followed.The influences of the mixture viscosity and the way of adding HDI biuret during the dilution on the properties of 2K-W PU,which was then characterized by particle size-testing instrument.TEM and rI'IR,were also investigated.The results indicate that:(1)the phase inversion 0f 2K-WPU OCCUrs at a solid content of the mixture of 45%(mass fraction).(2)if added before the phase inver.sion point of waterborne acrylic resin.HDI biuret will disperses in water.achieving a stable 2K-WPU emulsion.(3)according to the TEM results,2K-WPU particles possess the core.shell structure,in which HDI biuret is en.capsulated by waterborne acrylic resin,(4)the 2K-WPU emulsion with HDI biuret is of larger particle size and narrower particle distribution than the acrylic resin emulsion,while the 2 K-WPU emulsion with HDI isocyanurate trimer possesses not only a larger particle size but also a double-peak particle distribution，and(5)according to the FTrIR results．the curing reaction between HDI biuret and warerborne acrylic resin completes in 1 2 h．

Key words: HDI biuret, waterborne acrylic resin, polyurethane, mixture, preparation, characterization