Study On Synthesis And Printability Of The New Aqueous Polyurethane For Flexible Packaging Printing Ink

Waterborne ink binder has been synthesized with water as solvent in stirring and emulsifing at high-speed which can be obtained water-based polyurethane emulsion. Aqueous polyurethane ink are non-toxic and safe, do not pollute the environment . So the aqueous polyurethane ink binder has a certain theoretical significance and practical value.With the raw materials of domestic commercial by condensation and chain extender was prepared aqueous polyurethane ink binders,and prepared the water-based with aqueous polyurethane ink binders.The synthesis process of aqueous polyurethane ink can be approximately divided into the following steps in the experiment:(1) The synthesis of a chain extender that is low molecular weight polyester diols: Low molecular weight polyester diols have been preparated in polycondensation reaction,with different types,different proportions of dicarboxylic acid and glycol in a certain conditione.The content of hydroxyl value of 2.5~5mmol/g.(2) Studied with the rotational rheometer on the rheology of the aqueous polyurethane ink binder. The results show that, the aqueous polyurethane is the pseudoplastic fluid and has the thixotropic property.(3) Synthesis and Optimization of aqueous polyurethane :By the once chain-extension and the secondary chain-extension was prepared water-bases polyurethane prepolymer,optimized the reaction time, the content of the catalyst , toluene-2,4-diisocyanate(TDI) and dihydromethyl propionic acid (DMPA).Then studied effect on the type and the amount of polyester diols. Known from experiments, with the pol-756 polyester diol, once chain-extension with number 21 #, secondary chain-extension with number 28# (the numbers are experiment numbers), the catalyst prescent of the total reactants is about 0.6%,the rage of R(-NCO/-OH) is 1.2 ~ 1.275, the content of DMPA is 9% to 10%. In the synthesis , with the way of the emulsion and neutralization to prepared the water-based polyurethane printing ink binder which has a good adhesion on non-polar soft packaging plastic film. Infrared spectroscopy and scanning electron microscopy was used for analyzing the molecular structure and microfacies of aqueous polyurethane. (4) Water-base ink was compounded with excellent compositive performances of aqueous polyurethane as ink binders.Studied the adhesion of the water-base polyurethane ink on non-polar soft packaging such as BOPP and the printing adaptability, such as viscosity,fineness, tack , Initial dryness test and so on.