Synthesis and application research of high phosphorus content epoxy resin with low dielectric loss
A high phosphorus content epoxy resin(DPOEP)was synthesized by using 2,5-dihydroxybenzyl(diphenyl)phosphine oxide(DPOHQ)and epichlorohydrin(ECH)as reactants,and then the structure of DPOEP was characterized by Fourier-transform infrared spectroscopy(FTIR)and nuclear magnetic resonance(NMR).The curing reaction characteristics of DPOEP with the curing agent of active ester resin DFE617 was studied,and the effects of DPOEP content and phosphorus-containing epoxy resin structure on the flame-retardant performance,dielectric properties,and thermal stability of dicyclopentadiene(DCPD)epoxy resin curing system were investigated.The results show that the curing process of DPOEP/DFE617 system follows a first-order reaction.DPOEP can promote the carbonization of condensed phase in the DCPD epoxy resin/DFE617 system,and the limiting oxygen index of cured resin reaches 36.6%-38%,achieving V-0 rating in the UL94 test.The dielectric loss factor of the epoxy resin curing system decreases with the increase of DPOEP content.At a lower content of DPOEP,the epoxy resin cured material is halogen-free and flame retardant while maintaining good thermal properties.
high phosphorus epoxy resincuring kineticsdielectric propertiesflame retardancythermal properties