Properties / Applications: Bayhydrol® UV XP 2690 is used for the formulation of waterborne UV coatings, especially for application on exterior wood materials. The addition of 1.0 to 2.5 ppw photoinitiator calculated on the solid binder, have proved suitable for initiating the curing reaction.Viscosity is set by the addition of polyurethane thickeners. Matting agents should be added in the form of pastes. After evaporation of the water, the coating is physically dry and can be handable. UV-curing up to 10 m/min. per 80 W/cm lamp will leads to results in a very high final quality. For the formulation of weather resistant coatings, the use of light protecting agents (preferably a combination of UV absorbers and hindered amine light stabilizers) is recommended. A modification of the photoinitiator component towards longer absorbing types (MAPO, BAPO) might be necessary. The resulting formulation should always be tested in weathering experiments with regard to the specific substrate, application and curing conditions. Bayhydrol® UV XP 2690 shows optimum weatherability and excellent chemical resistance. The films are hard and in the same time flexible. The product can also be combined with e.g. Bayhydur® XP 2655 or Bayhydur® 305 to produce ”dual cure ” waterborne UV coatings.

Information provided by Covestro