| 摘要 |
A method for preparing a polyurethane adhesive is provided to produce the partially cross-linked aqueous polyurethane adhesive having excellent initial adhesion, initial heat resistance, and water-dispersible stability. A method for preparing a polyurethane adhesive having improved heat resistance includes the steps of: (a) reacting polyester polyols with diisocyanate to prepare a polyurethane prepolymer having isocyanate groups at both ends of the molecule; (b) dissolving the prepolymer in an organic solvent comprising 3-8 carbon atoms and having a boiling point of 160 °C or below to prepare a self-emulsion type prepolymer having a controlled viscosity suitable for water dispersion; (c) adding water to the self-emulsion type prepolymer to perform emulsion; and (d) removing the organic solvent under reduced pressure. To introduce a partially crosslinked structure into the molecule, a polyfunctional alcohol having at least three alcohol functional groups is further added as a reactant when the prepolymer of the step (a) is prepared, or an amine having at least three primary amine groups in the molecule is further added after the emulsion process of the step (c). To introduce a hydrophilic group into the molecular chain, the preparation method further comprises a step of adding an aliphatic diamine having a sodium sulfonate group in the molecule before the step (b) or step (c). |
