The invention discloses a preparation method of a waterborne
polyurethane emulsion modified by a natural
monosaccharide compound. The preparation method comprises the following steps: firstly, adding polyglycol to a dry reaction
bottle, heating to melt the polyglycol in the reaction
bottle and vacuumizing to removal water for 1 hour at 120 DEG C; next, adding a hydrophilic
reagent, a chain
extender and diisocyanate to the reaction
bottle to have a
polymerization reaction, thereby obtaining a
polyurethane prepolymer; next, adding the natural
monosaccharide compound for reacting, cooling after a period of time, and adding an
organic base to regulate the pH value of the reaction; and adding deionized water under high speed stirring for emulsifying, and removing the
solvent by virtue of reduced pressure
distillation, thereby obtaining the waterborne
polyurethane emulsion modified by the natural
monosaccharide compound. According to the preparation method, the waterborne polyurethane is modified by use of the natural monosaccharide, and the product has excellent overall properties, and also is environment-friendly, harmless, cheap and the like. The
coating of the product can be just thermally decomposed at 300 DEG C; compared with the polyurethane before modification, the
heat resistance of the modified polyurethane is obviously improved, and meanwhile, the water tolerance of the modified polyurethane is also greatly improved.