Low Viscosity, High Strength Adhesive Materials with Low CTE

NanoSonic has developed a low viscosity, UV curable epoxy technology for fast adhering of optical components to ceramic glass substrates. The aliphatic epoxy adhesive formulations have viscosities 10 Poise and the fully cured networks display glass transition temperatures higher than 70 C using cationic photo initiation at ambient conditions. The adhesive formulation has successfully demonstrated curing inside of UV-opaque substrates via a dark cure mechanism. Dogbone specimens display tensile strength up to 36 MPa. Aluminum lapshear samples strength shows adhesive failure up to 26 MPa, while no ceramic glass lapshear failed in the bond area. CTE values for unfilled aliphatic epoxies were as low as 40 ppm C. A low viscosity, UV curable adhesive with high strength, high glass transition temperatures, and low coefficient of thermal expansion is needed as a replacement for hydroxide catalyst bonding used to bond mirrors and optics for Laser Interferometer Space Antenna and other structures. An injectable adhesive with stronger bonding strength is required to support precision aligned components during the expected launch loads of a telescope structure. UV curable aliphatic epoxy adhesives were developed as a fast setting, non-caustic, bonding technology under ambient conditions. The cationic photoinitiated aliphatic epoxy adhesive formulation displays tensile strength up to 36 MPa. The adhesive formulation has successfully demonstrated curing inside of UV-opaque substrates via dark cure mechanism. Aluminum lapshear samples strength shows only adhesive failure at 26 MPa, while no ceramic glass failed in the bond area indicating good adhesion. CTE values for the unfilled epoxies were as low as 40 ppm °C and dependent upon the precursor(s) structure and formulation. Establish commercially scalable synthetic procedures for producing novel functionalized UV-curable epoxy silane precursors. Formulate HybridSil epoxy silane systems containing functionalized inorganic nanoparticles as reactive modifiers to affect CTE and cure shrinkage and improve adhesion. Characterize HybridSil UV-setting epoxy resin cure profile, including cure time, depth of cure, and extent of cure. Measure the thermal and thermochemical properties and mechanical properties of the cured epoxy resin to establish structure – property relationships for optimalization adhesive formulation. Develop a feasibility plan to scale the down selected epoxy resin to pilot scale quantity Complete cost analysis on down selected UV curable resin materials and Phase III commercialization work plan
Benefits: A low viscosity, UV curable adhesive system that possess high strength, high glass transition temperatures (Tg), and low coefficient of thermal expansion can be used in precise bonding of Laser Interferometer Space Antenna (LISA) and other stable structure applications, as well as encapsulants in electronics and UV-stable coatings. UV curable epoxy based-precursors and polymers are used as adhesives, UV-stable coatings, encapsulants for electronics, inks, and paints/varnishes applications. The low CTE and dielectric properties make these materials attractive for electronics and specialty application.