Synthesis of Epoxy-Modified Methyl Phenyl Silicone Resins for LED Encapsulation

The epoxy-modified silicones have the advantages of both epoxy and organic silicon. In this paper, a series of epoxy-modified methyl phenyl silicone resins were synthesized through the hydrosilylation reaction between 1, 2-epoxy-4-vinylcyclohexane and methyl phenyl silicone resins. The effects of catalyst dosage, reaction time and temperature on the products were further discussed to determine optimal reaction conditions. Then, the as-prepared epoxy-modified silicone resins were cured with methylhexahydrophthalic anhydride. The curing kinetics was investigated through differential scanning calorimetry (DSC). The curing conditions were determined as follows: 1-h curing at 80 °C for and subsequent 1-h curing at 110 °C. The as-prepared products exhibited high light transmittance (~ 90% at 450 nm), strong bonding, suitable hardness and sound waterproof performance. In addition, the introduction of methylphenylsiloxane chain significantly improved the heat resistance and UV resistance of cured products. The epoxy-modified silicone resins are ideal LED packaging materials.