Abstract: The aminated lignin was prepared by Mannich reaction with alkali lignin, formaldehyde and diethylenediamine(DETA) as the raw materials. The structure of aminated lignin product was characterized by elemental analyzer, infrared spectrometer and nuclear magnetic resonance instrument, and its solubility and emulsifying properties were analyzed. The infrared spectrum and ¹H NMR spectrum analyses also demonstrated that the diethylenediamine was successfully grafted to the benzene ring of lignin. The grafting rate was less affected by temperature and time and more affected by raw material ratio. When the temperature was 80℃, the reaction time was 6 h, the molar ratio of formaldehyde and DETA was 3 and the mass ratio of DETA and lignin had 1.55, the nitrogen content of aminated lignin could reach the maximum of 16.95%. The experimental results showed an obvious correlation between the grafting rate and solubility in acidic solution. When the nitrogen content of aminated lignin reached above 16.59%, its solubility in acid conditions reached 100%. The acid soap solution was prepared by using aminated lignin in the mass fraction of 5% and the pH value of 2, and the aspHalt emulsion was prepared in the concentration of 62% using this acid soap solution. As the examination results showed, the better solubility of aminated lignin had, the better performances of the aspHalt emulsion had. When the nitrogen content of lignin reached above 16.95%, the residual volume of aspHalt emulsion was 0, and the storage stability of 1 and 5 days was less than 1% and 5%, respectively. The average particle size of the emulsion reached 2.2 μm.

Key words: aminated lignin, acid solubility, diethylenetriamine, nitrogen content