Synthesis And Performance Research Of A Kind Of Epoxy Resin Containing Three Phenolic Groups And Ethyl Group With High Refractive Index

Epoxy resins with many excellent properties such as strong bonding, good heat resistance, small shrinkage rate and low cost have been widely used for LED packaging materials. However, the refractive index of epoxy resins used for LED packaging materials currently is generally low, which greatly influences the LED light out-coupling efficiency and reduces the working life of the LED chip. Therefore, study and synthesis of new type epoxy resins with high refractive index is a meaningful research and has broad application prospects.The epoxy resin containing three phenolic groups——tri(4-hydroxyphenyl)ethane epoxy resin(E-THPE) was synthesized in the thesis. Different synthesis process conditions affecting the yield of tri(4-hydroxyphenyl)ethane(THPE) and the epoxy value of E-THPE were studied. The structures of THPE and E-THPE were characterized by IR and1H NMR. The maximum epoxy value of E-THPE is up to0.529mol/100g and the maximum refractive index of E-THPE is up to1.6180.Hexahydrophthalic anhydride(HHPA) and methyl nadic anhydride(MNA) as the curing agents, E44epoxy resin and E-THPE as the resins,2-methyl imidazole as the promoter, composed four kinds of curing systems. Their curing processes were explored by non-isothermal DSC technology. The appropriate curing process parameters were determined and the curing dynamics were analyzed.Aimed at four selected curing systems, a series of researches about the differences between the properties of four kinds of cured epoxy resins and the effects of kinds and amounts of promoters and curing agent dosage on the properties of cured epoxy resins were carried out. The introduction of E-THPE and MNA improves the refractive index, bending strength and Tg of cured epoxy resins, reduces the impact strength and has no obvious effect on light transmittance. Two kinds of promoters2-methyl imidazole and benzyltrimethylammonium chloride(TMBAC) can both improve the refractive index, bending strength, impact strength and Tg of cured epoxy resin to a certain extent. When the molar ratio of E-THPE to MNA is1:0.8, the refractive index, bending strength and impacting strength reach up to1.6112,130.6MPa and13.8kJ·m-2. Tg decreases with the increase of dosage of MNA. The dosage of MNA, the kinds and amounts of promoters have no obvious effect on light transmittance.E44epoxy resin was used to improve the toughness of E-THPE/MNA/2-methyl imidazole cured epoxy resin. With the increase of E44content in the curing system, the refractive index, bending strength and Tg have a small decline, but the impact strength has been enhanced.