Bayhydrol PT 241 Polyester polyurethane resin Bayer MaterialScience Polyurethane (PU) - Polyurethane dispersions (PUDs) >> Polyester Coatings >> Waterborne Automotive OEM >> Primer / Surfacer Automotive refinishing >> Clearcoat General Industrial /Maintenance Plastic coating >> Primer Plastic coating >> Topcoat water/N-methyl pyrrolidone, neutralised with dimethyl ethanol amine 53:5:1 Polyester polyurethane dispersion In the formulation of stoving industrial coatings, stoving automotive primer surfacers and two-pack polyurethane primers and top coats for plastics. The viscosity of Bayhydrol PT 241 is greatly influenced by the pH. As the pH may decrease during storage, a corresponding decrease in viscosity is to be expected. It can be restored to its original value by the addition of small amounts of dimethyl ethanol amine. Bayhydrol PT 241 is a polyester-polyurethane dispersion neutralised with dimethyl ethanol amine which is resistant to hydrolysis. The product can be thinned with water for application and shows no thinning anomalies. Bayhydrol PT 241 can be combined with partially methylated melamine resins to formulate water-thinnable stoving coatings and primers which cure in 30 min at 120 °C. The ratio of Bayhydrol PT 241 to the amino resin (calculated on the solvent-free resin) is usually 75 : 25 to 70 : 30. Given the many amino resins on the market, compatibility should always be tested. Coatings based on Bayhydrol PT 241 will remain stable for at least 6 months at room temperature. It should be ensured that the coating is adjusted to a pH of 8.7-9.0 after formulation. Bayhydrol PT 241 is characterised by its good pigment wetting and high shear stability. Suitable grinding equipment includes sand and bead mills. Pigments and extenders are ground in some of the amount of Bayhydrol PT 241 for the formulation, with the addition of deionised water, to set the necessary dispersion viscosity. Because of the outstanding shear stability of Bayhydrol PT 241, dispersion temperatures up to approx. 50 °C have no negative effects. Optimum pigment wetting is achieved by adding the total amount of dimethyl ethanol amine required to adjust the pH of the coating to 8.7 to 9.0 during grinding. Only pigments and extenders with the minimum possible water-soluble content should be used. Given the many different pigments and extenders on the market, the storage stability should always be tested. Suitable pigments include all rutile products from the Kerr- McGee1 range, preferably Tronox R-KB-4. The flow of spray and dip coatings can be optimised by the addition of, e.g. BykÒ 3012. Polyester polyurethane dispersion neutralised with dimethyl ethanol amine. Used in the formulation of stoving industrial coatings, stoving automotive primer surfacers and two-pack polyurethane primers and top coats for plastics. Offers resistance to hydrolysis. Can be combined with partially methylated melamine resins to formulate water-thinnable stoving coatings and primers. Provides good pigment wetting and high shear stability.