Synthesis and properties of epoxy resins containing bis(3-hydroxyphenyl) phenyl phosphate

A reactive phosphorus-containing diol compound, bis(3-hydroxyphenyl) phenyl phosphate (BHPP), was synthesized. The compound (BHPP) was used as a reactive flame-retardant for diglycidyl ether of bisphenol-A (DGEBA). Thermal stability and the weight loss behavior of the cured polymers were studied by thermogravimetric analysis. The phosphorous-containing epoxy resin showed lower weight loss temperature and higher char yield than that of DGEBA. The high char yields and limiting oxygen index values as well as excellent UL-94 vertical burn test results of BHPP/DGEBA indicated the flame retardancy of the phosphorous-containing epoxy resins. The resulting phosphorous-containing epoxy resin exhibited better flame retardancy and higher thermal stability than the regular bromine containing flame retardant epoxy resin in encapsulation application. UL 94-VO rating could be achieved with a phosphorus content of as low as 1.5% (comparable to bromine content of 10%) in the cured resin, and no fume and toxic gas emission were observed.