Polyisocyanate hardeners as reaction partners in waterborne dispersion
In order to obtain the best possible properties and to facilitate good processing with waterbased polyurethanes the ease of mixing is critical. Bayer MaterialScience has developed hydrophilized polyisocyanate hardeners (Bayhydur®) for this purpose. They only need little shear energy when incorporating them into Bayhydrol® polyol dispersions. The properties of a two-component waterbased coating depend largely on the level of hydrophilization, which in turn determines how easily the two components can be mixed. It is even possible to incorporate hydrophobic polyisocyanates of the Desmodur® range like the low-viscosity Desmodur® N 3900 into waterbased systems. This can easily be realized with a two-component mixing equipment. Incorporating hydrophobic polyisocyanates into a polyol dispersion gets much easier when it is combined with a hydrophilic grade like the Bayhydur® XP 2655.
hand-mixed
hand-mixed jet-mixed
Bayhydur®
Hydrophilic polyisocyanate
Easy emulsification
Homogeneous crosslinking
Broad range of applications
High gloss / transparency
easy to obtain
Desmodur®
Hydrophobic polyisocyanate
Better weather resistance
Better chemical resistance
Lower water uptake
Higher hardness
Properties of two-component waterborne coatings are also influenced by the degree of hydrophilization, which determines the blending characteristics of the two components.
The new Bayhydur® XP 2759 - An ideal combination of efficiency and user friendlyness
A new hydrophilic polyisocyanate with an interesting property profile is our Bayhydur® XP 2759. This IPDI-based crosslinker, which is commonly formulated with HDI-based polyisocyanates, combines efficiency, outstanding properties and user friendlyness in an ideal way. The product shows fast drying, a long pot-life and a good popping limit. The resulting coating films exhibit a high hardness and good weather resistance.
Have a look at the entire product line of hydrophilic polyisocyanates - Overview - Product data sheets
(Please register e.g. login if you would like to see the entire product line including all trial products)
An overview of Bayhydur product portefolio you can find here
Low viscosity Desmodur® grades can be used as hardeners in order to enhance the chemical resistance. They can also be formulated in combination with Bayhydur® polyisocyanates to modify the viscosity or to optimize the property profile of the finished coating.
Get more information on aliphatic polyisocyanates to be used as crosslinkers in waterborne two-component polyurethane systems here.
The low viscosity Desmodur® polyisocyantes are particularly suitable as crosslinkers for the hydroxy-functional Bayhydrol® grades Bayhydrol® A and Bayhydrol® U; on top of that, Bayhydur® polyisocyanates can be used for post-curing of higher molecular dispersions (Bayhydrol® UH range), Bayhydrol® UA, Bayhydrol® AH and for adhesives dispersions of the Dispercoll® U type. (Please be sure to login to see all products, including trial products)
Technical data and application information in these product overviews and brochures:
