Hydrophilic modification is key
Polyisocyanate crosslinkers improve properties of waterborne coatings
The degree of hydrophilic modification determines the blending characteristics and properties of two-component (2K) waterborne coatings. In order to optimize the application and the performance properties of 2K waterborne polyurethane (PU) coatings, Covestro developed a variety of Bayhydur® hydrophilically modified polyisocyanates.
Bayhydur® hydrophilically modified HDI polyisocyanate crosslinkers for 2K waterborne PU systems facilitate ease of mixing when incorporated into Bayhydrol® polyol dispersions.
Hydrophilically modified IPDI-based crosslinkers are commonly formulated together with HDI-based polyisocyanates. Together they combine efficiency, outstanding properties and user friendliness in an ideal way. The product offers fast drying and longer pot life. The resulting coating provides high hardness and good weather resistance.
Desmodur® low-viscosity hydrophobic polyisocyanates are also used as hardeners in water-based systems. They enhance chemical resistance and performance of the finished coating. They are usually incorporated into water-based systems by using 2K mixing equipment. The addition of a hydrophilic grade makes this process easier.
All hydrophilically modified polyisocyanates are suitable as crosslinkers for the hydroxy-functional Bayhydrol® A and Bayhydrol® U dispersion grades.
Additionally, Bayhydur® polyisocyanates are used for post-curing of Bayhydrol® UH and Bayhydrol® UA non-functional dispersions to further improve properties.