Evaluation of Sealing Properties to LED Light Emitting Substrate of Organic-inorganic Hybrid Materials Composed of Polysilsesquioxane with Thiol Group

Novel organic-inorganic hybrid materials were developed as LED sealants. Polysilsesquioxane with an -SH group (PSQ-SH) and acrylic monomer were selected as the inorganic and organic components, respectively. Trimethylolpropane trimethacrylate (TRIM), which is a trifunctional monomer, was selected as an acrylic monomer, and curing of the material was performed by the thiol-ene reaction. The LED was sealed using the prepared PSQ-SH/TRIM hybrid material (PTH), and a light emission test was performed. However, cracks occurred in the hybrid material during lighting. Therefore, ditrimethylol propane tetraacrylate (DTMPTA), which is a tetrafunctional monomer, was selected for the first time to prepare a PSQ-SH/DTMPA hybrid material (PDH) in order to enhance the strength and heat resistance of the material. The characteristics of the novel PDH were evaluated and compared with those of PTH. Specifically, the heat resistance was evaluated by confirming the onset temperature of weight reduction using thermogravimetry-differential thermal analyzer (TG-DTA) analysis, and the mechanical strength was also evaluated by bonding the glass substrates with a hybrid material and measuring the sealing strength. In conclusion, it was possible to suppress crack generation during lighting by using PDH instead of PTH in the light emission test.