Method for preparing waterborne polyurethane adhesive based on hexamethylene diisocyanate (HDI)-toluene diisocynate (TDI)

The invention discloses a method for preparing a waterborne polyurethane adhesive based on hexamethylene diisocyanate (HDI)-toluene diisocynate (TDI). A diisocyanate system formed by combining polyester polyol, the TDI and the HDI is reacted to produce a prepolymer, hydrophilic chain extender and a polyatomic alcohol monomer are added for further reaction, chain extension is performed based on micromolecule dihydric alcohol, and finally the waterborne polyurethane adhesive based on the TDI and the HDI is prepared. The solid content of the prepared waterborne polyurethane adhesive can reach to40-50%, initial adhesion is large, and cohesive strength is high. When the waterborne polyurethane adhesive is used, heat-resisting temperature can reach above 160 DEG C without adding a curing agent, the viscosity is controlled in a range of 200-500cp, and polyvinyl chloride (PVC)/ PVC peel strength can reach 5-7N/mm2.