Urethane Acrylates from Oligomerric Hexanenthylene Siisocyanate Derivatives

Urethane acrylates as binders for UV curable coatings offer an excellent property profile combining toughness, chemical and abrasion resistance with flexibility and, for the aliphatic types, outdoor resistance. Most of the excellent properties can be attributed to the hydrogen bridge bonding of the urethane groups. However, the same hydrogen bridge bonding is the reason why formulations based on urethanes usually suffer from rather high viscosity. Hexamethylene diisocyanate (HOl) is a versatil starting material for urethane acrylates. HDI can be used to synthesize oligomeric derivatives with different structures like isocyanurate, biuret, uretdione, allophanate and iminooxadiazindione. We investigated the influence of the structure of the derivative on the properties of the corresponding urethane acrylates. New low viscosity urethane acrylates and their potential for outdoor applications are discussed.