| Bayhydrol A 2227/1 is a polyester-polyacrylate dispersion. In the formulation of stoving industrial coatings with high whiteness retention on exposure to high temperatures. Also in the formulation of two-component polyurethane primers and top coats for plastics. Properties / Applications: The viscosity of the product is highly dependent on the pH. As the pH may decrease during storage, a decrease in viscosity must also be expected. The viscosity can be restored to its original value by adding small amounts of an aqueous 10% solution of dimethyl ethanol amine. Stoving industrial coatings: To ensure optimum pigment wetting, the pH should be adjusted with aqueous dimethyl ethanol amine (10%) to between 8.5 and 9. Details can be found in the relevant guide formulations. Combined with melamine resins, Bayhydrol A 2227/1 can be used to formulate stoving top coats with less than 5% co-solvent content at application viscosity. The coatings cure at stoving conditions from 30 minutes at 120°C. The ratio of Bayhydrol A 2227/1 to amino resin (solids on solids) is usually 80 : 20. Given the many different amino resins available on the market, compatibility tests should always be carried out. As it is a hydroxyfunctional binder, Bayhydrol A 2227/1 is also suitable for use as a co-reactant for aqueous aliphatic polyisocyanates. An OH/NCO ratio of 1 : 1 should be used. To achieve good storage stabilities of coatings based on Bayhydrol A 2227/1 the pH of the coating should be adjusted to between 8.5 and 9 after formulation. Coatings for plastics: In the case of coatings for plastics, we recommend the use of Bayhydur 302. An OH/NCO ratio of 1 : 1.5 should be used. Bayhydrol A 2227/1 is characterized by its good pigment wetting properties and high shear stability. Bead and sand mills have proved suitable as grinding equipment. Grinding temperatures of up to approximately 50°C have no detrimental effect on quality of the coating. Given the many different pigments available, the storage stability should always be tested. The rutile titanium dioxide pigments of the Tronox range, especially Tronox® R-KB-4, are particularly suitable. As with any product, use of Bayhydrol A 2227/1 in a given application must be tested (including but not limited to field testing) in advance by the user to determine suitability. Information provided by Covestro |
