Preparation And Properties Of High Rrefractive Silicone Encapusulating Materials For LED

Both epoxy resins and silicone materials have widely been used in the field of LED encapsulation and they possessed specific and different advantages and shortcomings.Epoxy modified silicone materials integrate the excellent performance of epoxy and silicone resins,thus they are more suitable for the requirement of LED encapsulation development.The article aims to obtain high-performance LED encapsulation materials and modifies silicone encapsulation materials at the level of molecule.Epoxy modified silicone materials were prepared and exhibited good comprehensive properties.The main contents are shown as follows:1.Cycloaliphatic epoxyphenyl cyclotetrasiloxane was synthesized by the hydrosilylation of 1,2-epoxy-4-vinyl-cyclohexane(VCMX),dimethylphenylvinylsilane(DMPVS)and 1,3,5,7-tetramethylcyclotetrasiloxane(TMCTS).Then the epoxyphenyl cyclotetrasiloxane was cured with anhydride.The encapsulation materials showed high hardness(41 D~82 D),good optical transparency(above 90% in the range of visible wavelengths),high refractive index(about 1.51),excellent thermal stability(the temperature of 5 wt% loss was in the range from 339 °C to 353 °C),low water absorption ratio,superior adhesive property and thermal/UV light resistance.The prepared materials were suitable for LED encapsulation.2.A series of epoxyphenylvinyl polysiloxane(EPVS)with different epoxy value and vinyl contents were prepared through the nonhydrolytic sol-gel condensation of diphenylsilanediol(DPSD),methylvinyldimethoxysilane(MVDMS)and3-glycidoxypropyldimethoxymethylsilane(GPDMS).In the presence of Pt Karstedt's catalyst,the LED encapsulation materials with high refractive index and self-adhesion properties were produced by the hydrosilylation of the novel epoxyphenylvinyl polysiloxane(EPVS)and methylphenyl hydrogen-containing silicone resin.The obtained encapsulation materials exhibited suitable hardness(31 D~47 D),goodoptical transparency(92% at the wavelength of 450 nm),high refractive index(about1.55),low water absorption ratio(<2.71% after immersing in water for 168 h),excellent thermal stability(the temperature of 5 wt% loss was above 360 °C),superior adhesive property and thermal/UV light resistance.These results proved that the prepared encapsulation materials have great potential in the application of LED encapsulation field.