Innovative UV LED Curable Resins for Optical Coatings for Medical Applications and Materials Processing

UV curable resins for optical coatings are of special interest, since the fast curing of resins by UV LEDs allow fast processing of the materials and short production times.[1,2] Beside the processing properties of the resins also thermal and mechanical properties have to fulfill increasing requirements, such as thermal stability, low optical propagation loss and high mechanical stability. Fluorinated polymers, especially acrylates and methacrylates, with low refractive index (n < 1.39 at 1550 nm) were investigated and the development of a modular system of resins was necessary in order to achieve these properties.[3] The studied thermosetting polymers provide an excellent curing behavior especially for UV LED cure. It was found that the resins cure very fast and completely by irradiatio n with 390 nm UV LEDs,figure 1. The glass transition temperature as well as the curve of the loss factor and the modulus were determined by dynamic mechanical analysis. A broad peak between 0 °C and 150 °C was observed at the curve of the loss factor. This indicates a large glass transition state of the thermosetting polymer. Additionally the modulus decreased slowly but steadily over this large range.