A novel thermal curing reaction of oxetane resin with active diester

Thermal curing reactions of oxetane resins {mixtures of novolac type oxetane (PNOX) with 2,2'-bis[(3-ethyl-3-oxetanyl)methoxy}biphenyl (2,2'-BPOX) and mixtures of tris{4-[(3-ethyl-3-oxetanyl)methoxy]phenyl}methane (THPMOX) with 2,2'-BPOX with active diester, 4,4'-isopropylidenebis(2,6-dichlorophenyl diacetate) (IBDCPA) were examined using certain quaternary phosphonium salts as catalysts. The thermal curing reaction of oxetane resins with IBDCPA proceeded smoothly at 170-190 degrees C to produce insoluble gel products. However, the rate of gel production was strongly affected by catalyst concentration and reaction temperature, and gel products were obtained in the highest yield when the reaction was carried out at 190 degrees C in bulk using 7 mol % of tetraphenylphosphonium chloride (TPPC) as a catalyst. The glass transition temperatures (T-g)s and 5 weight-% of loss temperatures (T-d(5%))S of the resulting gel products were determined by DSC and TGA analysis, and it was found that their T(g)s and T(d)(5%)s were 97-118 degrees C and 374-380 degrees C, respectively, when the thermal curing reaction of oxetane resins PNOX/2,2'-BPOX with equivalent amount of cross-linker IBDCPA was performed using TPPC as a catalyst in bulk. On the other hand, the T(g)s and T-d(5%) s of gel products obtained from the reaction of oxetane resins THPMOX/2,2'-BPOX with IBDCPA using the same catalyst were 96-128 degrees C and 381-386 degrees C, respectively.