DEVELOPMENT OF AN EFFICIENT UV LED-CURABLE COATING FORMULATION FOR ENERGETIC PARTICULATES

摘要

Among numerous advantages of the ultraviolet light emitting diode (UV LED) lamps over traditional mercury UV sources, very low heat generation is of special interest for the curing of surface coating of heat sensitive energetic and combustible particulates such as RDX and propellants. The surface coating of energetic particles would decrease their sensitivity, reduce friction and provide protection against environmental conditions. However, the development of a suitable formulation for such coatings is challenging due to the lack of efficient photo-initiators. In this study, the formulation of UV LED-curable chemicals composed of acrylates and photo-initiators were developed; their curing mechanisms under UV LED were studied with Photo-DSC which was equipped with a UV LED spot-curing system. By comparing the amount of heat release upon UV LED spot lamp irradiation, five photo-initiators were screened. The effect of oxygen on curing rates was also investigated. The results showed that the formulations with Esacure TPO as the photo-initiator under N_2 gave the fastest curing rates; the system can be completely cured in 30 seconds. Fluidized bed coating process of stimulant particulates with the irradiation of UV LED lights was developed and evaluated, which will be used to coat energetic particles.