Bayhydrol PT 355 Polyester polyurethane resin Bayer MaterialScience Polyurethane (PU) - Polyurethane dispersions (PUDs) >> Polyester Coatings >> Waterborne Aliphatic, hydroxyfunctional polyester polyurethane dispersion. Binder for the formulation of water-thinnable soft-feel coatings. Aliphatic, hydroxyfunctional polyester polyurethane dispersion. Used for the formulation of water-thinnable soft-feel coatings.