Properties / Applications: Bayhydrol® A XP 2770 is a hydroxyfunctional polyacrylic dispersion which can be thinned with water to application viscosity. Bayhydrol® A XP 2770 combined with aliphatic polyisocyanates yields high-gloss top coats which can be dried at room temperature or force-dried, e.g. at 80 °C. The cured paint films are hard and flexible with outstanding resistance to solvents and water and excellent weatherability. When properly formulated, e.g. in combination with Bayhydur® 304 in an NCO / OH ratio of 1.5 : 1, the pot life is approx. 4 hours. Bayhydrol® A XP 2770 has good pigment wetting properties and high shear stability. Bead mills have proved suitable as grinding equipment. Only pigments and extenders with a minimum water-soluble content should be used. Given the many pigments and extenders available, compatibility testing should always be carried out. When mixing Bayhydur® or Desmodur® into the mill base, a thickener must be added to ensure a high shear effect. The addition of approximately 0.4 % Borchigen® PW 25 (calculated on the solid binder) has proved suitable for formulations based on Bayhydrol® A XP 2770. Levelling and substrate wetting can be optimised by adding, for example Byk® 349 and Byk® 378. Byk® 011 has proved to be a suitable antifoam. Application and formulation equipment can be cleaned with water, alkaline cleaning agents or isopropanol.

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