Waterborne polyurethane adhesives have problems such as […]
Waterborne polyurethane adhesives have problems such as slow drying speed, poor wettability to non-polar substrates, low initial tack, and poor water resistance. At the same time, the hardness and mechanical properties of the latex film are far from sufficient.
(1) Adjusting the structure Under the premise of ensuring the stability of the emulsion, the content of the hydrophilic group is as low as possible, and the water resistance of the film can be improved;
(2) Improved process The heat treatment of the emulsification equipment with excellent process performance can improve the strength and water resistance of the film.
(3) Composite modification In order to improve certain properties of waterborne polyurethane, it can be blended with other water-based resins such as epoxy resin emulsions, urea-formaldehyde resins, etc. to form new water-based adhesives, and the performance thereof is improved.
(4) Graft modification A suitable amount of styrene monomer was added to the polyurethane emulsion, and a polyurethane-styrene graft emulsion was prepared by in-situ polymerization to improve adhesion and water resistance.
(5) Vinyl emulsion dispersion modification The polyisocyanate (or its prepolymer) organic solution can be dispersed in an aqueous solution of polyvinyl alcohol or carboxymethyl cellulose.
(6) Crosslinking modification is an effective method for improving the performance of waterborne polyurethane, and can improve the water resistance, heat resistance and bonding strength of the film.