Synthesis of Bisphenol A Based Phosphazene-Containing Epoxy Resin with Reduced Viscosity

Abstract

Phosphazene-containing epoxy oligomers (PEO) were synthesized by the interaction of hexachlorocyclotriphosphazene (HCP), phenol, and bisphenol A in a medium of excess of epichlorohydrin using potassium carbonate and hydroxide as HCl acceptors with the aim of obtaining a product with lower viscosity and higher phosphazene content. PEOs are mixtures of epoxycyclophosphazene (ECP) and a conventional organic epoxy resin based on bisphenol A in an amount controlled by the ratio of the initial mono- and diphenol. According to 31P NMR spectroscopy, pentasubstituted aryloxycyclotrophosphazene compounds predominate in the ECP composition. The relative content in the ECP radicals of mono- and diphenol was determined by the MALDI-TOF mass spectrometry method. The organic epoxy fraction, according to gas chromatograpy-mass spectrometry (GC-MS), contains 50–70 wt % diglycidyl ether of bisphenol A. PEO resins obtained in the present work have reduced viscosity when compared to other known phosphazene-containging epoxy resins while phosphazene content is still about 50 wt %. Resins with an epoxy number within 12–17 wt %, are cured by conventional curing agents to form compositions with flame-retardant properties, while other characteristics of these compositions are at the level of conventional epoxy materials.

Transparent epoxy resin material with excellent fire retardancy enabled by a P/N/S containing flame retardant

“…So, it is extremely important to ameliorate the fire safety of EP. At present, the most widely used method is additive flame retardants to improve the flame retardancy 7–10 . However, the low transparency, environmental pollution, or high‐addition amount are the main disadvantages of its application, 11,12 especially for coatings and circuit boards.…”

Synthesis and Application of Arylaminophosphazene as a Flame Retardant and Catalyst for the Polymerization of Benzoxazines

“…The other example is hexaphenoxycyclotriphosphazene, which is used as a highly effective flame retardant for a large number of synthetic polymers. A number of effective flame-retarded functional epoxy resins, amine curing agents and benzoxazines with a phosphazene core have been proposed [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Carboxyl-containing epoxyphosphazenes and their use as a catalyst for the polymerization of benzoxazines have also been reported [ 22 ].…”

Isothermal Kinetics of Epoxyphosphazene Cure

“…Arylphosphazenes compared with other organophosphorus compounds, have, as a rule, higher thermal stability and chemical resistance and are promising fire retardants [ 4 , 6 , 13 , 14 ], characterized by the synergistic effect of phosphorus and nitrogen [ 15 ]. Thus, phenoxycyclophosphazenes were commercialized as a flame retardant by Otsuka Chemical et al Recently it was shown that epoxy-amine matrices modified with epoxycyclophosphazene [ 16 ] are characterized by enhanced mechanical properties [ 17 ]. Therefore, epoxy resins modified with epoxycyclophosphazenes appear to be a promising base for halogen-free binders for critical use.…”

“…Therefore, epoxy resins modified with epoxycyclophosphazenes appear to be a promising base for halogen-free binders for critical use. Recently, scalable methods for epoxycyclophosphazene synthesis have appeared [ 6 , 16 , 18 ], which make it possible to believe that they may become available starting components in the market for composite manufacture.…”

“…This work is dedicated to the study of the isothermal curing of the epoxy-amine matrix modified with epoxycyclophosphazene [ 16 ]. In particular, the modifier influence on the main kinetic parameters of the curing process is revealed.…”