长链烷基脲类消泡剂的合成及性能研究

Developing silicon-free defoamer is one of the development directions in the field of defoaming agent in the future. In this work, three long-chain alkyl ureas were prepared via the reaction of 1-isocyanatooctadecane with oleylamine, 1,6-hexanediamine and tris (2-aminoethyl) amine, respectively, and three urea defoamers were formulated with alkyl urea as active substance, mineral oil as carrier, and Span-Tween as emulsifier. The structure of the products was characterized by nuclear magnetic resonance spectroscopy (¹H NMR) and Fourier transform infrared spectroscopy (FT-IR). The defoaming process and mechanism of hydrophobic particles in oil-based defoamers were studied by microscopic method. Through single factor experiments, the influences of each composition and dosage on the performance of defoamer were explored. The results indicate that when the low viscosity white oil was selected, and the urea active substance accounted for 4% of the defoamer mass fraction, the Span-Tween compound emulsifier has hydrophilic-lipophilic balance (HLB) value of 8 and the mass fraction of the defoamer is 5%, the urea defoamer had better defoaming performance than similar commercial products in coating application.