Abstract
A novel epoxy resin (DGEHMB) was prepared in two step reactions using 2, 2', 3, 3', 5, 5'-hexamethyl 4, 4'-biphenol as a starting material. Because of the biphenol being hardly soluble in aq.NaOH solution, the reaction of the biphenol with epichlorohydrin was carried out using a phase transfer catalyst, tetrabutylammonium bromide, at 90°C in the absence of alkali, followed by epoxidation with aq.NaOH solution at a lower temperature (<10°C). Melt viscosity of the DGEHMB obtained was a little higher than that of a commercial 2, 2', 3, 3'-biphenol diglycidyl ether (YX 4000TM) : for example, the melt viscosities (poise) at 150°C of DGEHMB and YX 4000 were 2.2 and 0.13, respectively. Differential thermal analysis indicates that the curing reactivity of DGEHMB was similar to that of YX 4000 when using methyl hexahydrophthalic anhydride (MHHPA) as a curing agent. Flexural strength and modulus of the MHHPA-cured DGEHMB resin were larger than those of the YX 4000 resin. The Tg value of the cured DGEHMB resin was similar to that of the cured YX 4000 resin.
