New low viscous Urethane Acrylates

摘要

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 these properties can be attributed to the hydrogen bridge bonding of the urethane groups. However, the same hydrogen bridge bonding is the reason why urethane acrylates usually suffer from rather high viscosity, making it necessary to add high amounts of reactive thinners to achieve viscosities suitable for coatings application. Increasing amounts of reactive thinners reduce the properties of resins dramatically. According to this, low viscous urethane acrylates were developed and discussed, including: 1. Products for indoor application, synthesized from aceotropic precursors and diisocyanates. 2. Products based on Hexamethylene diisocyanate (HDI). HDI is a very versatile starting material for urethane acrylates with different oligomeric structures like isocyanurate, biuret, uretdione allo-phanate and iminooxadiazindione. We investigated the influence of the structure of the HDI derivative on the properties of the corresponding urethane acrylates and evaluated the potential for outdoor applications.