| abstract |
The present invention discloses flame retardant compounds, hardeners and polyphenol-based epoxy resins. In the molecular structure, such flame retardant compounds contain phenolic hydroxyl groups, and groups M of nitrogen phosphorus skeleton consisting of unsaturated phosphorous and nitrogen atoms, wherein M contains at least 50 wt% of cyclotriphosphazene groups M 1 , at most 48 wt% of M 2 , which is a cyclic ring consisting of four or more phosphazene groups, and at most 48 wt% of non-cyclic polyphosphazene groups M 3 . Therefore, such flame retardant compounds have better flame retardancy, and the cured products thereof have better heat resistance, water resistance, cohesiveness, mechanical property and electrical property. Additionally, such compounds can improve flame retardancy, economy and envionmental friendly protection when applied in composite metal laminates and circuit boards. |