Tung Oil Modified Waterborne Polyurethane And Its Application In Ink

Waterborne polyurethane(WPU) not only has excellent physical and chemical properties of polyurethane materials, and both has the advantages about security, environment, low costing or other features. However, because of presence of hydrophilic groups in molecular structure, which gives WPU inherent poor water resistance, and its comprehensive performance can not compare with solvent-based polyurethane. Tung oil is Chinese characteristics renewable biomass resources with three conjugated double bonds on molecule and it can be introduced in to WPU molecules, which can not only improve the water resistance of WPU, but also can increase the application range of natural renewable resources, catering the requirements of conservation of resources and environmental protection. In this paper, tung oil was transformed into tung oil-based diol through interesterification, then this diol was used in the synthesis of WPU to prepare a series of tung oil modified waterborne polyurethanes, at last, waterborne inks were prepared with WPU as binders. It can be summarized as follows:(1) Tung oil and glycerol were used as basic raw materials to synthesize tung oil-based diol through interesterification with sodium methoxide as catalyst. Infrared spectroscopy, Ultraviolet Visible Spectometer and 1H NMR were used to characterize the structure; At last, the reaction condition of interesterification was optimized, that is the reaction temperature is 210℃, the content of catalyst is 0.5%, the reaction time is 4h.(2) Tung oil modified waterborne polyurethanes with good water resistance were synthesize with tung oil-based diol as modifier. Infrared spectroscopy, TG, DSC, SEM, rotational rheometer and Digidrop Contact angel Meter were used to characterize the structure and performance of the products. The influence of tung oil-based diol content, POL content, DMPA content, and neutralization on the performance of the waterborene polyurethane were studied.(3) Waterborne gravure inks were prepared with tung oil modified waterborne polyurethane as binder mixing with blue pigment andadditives, the influences of ratio about pigment to binder on inks were studied. The result shows: as the content of resin increases, the storage stability, adhesion on PET film and gloss of waterborne ink all increase, and it can meet the requirements of gravure printing as the fineness, viscosity, rheology and water resistance and so on.