Synthesis And Properties Of A Flame Retardant Silicon-Containing Curing Agent Of Epoxy Resin

Epoxy resins are widely used in electronic packaging materials, printed circuit board and adhesives, etc. Due to the flammability of epoxy resins, their applications are limited. Curing agents are very important in the application of epoxy resins, so it is necessary to study the halogen-free flame retardanted curing agent which is environmentally friendly. The halogen-free flame retardanted curing agents mainly included phosphorus-containing, silicon-containing and nitrogen-containing curing agents. Silicon-containing curing agent is concerned extensively due to its high thermal stability, oxidation resistance and less smoke when it's burning.It is tried to synthesize the desired product bis(4-aminophenoxy) dimethyl silane(APDS) by three different methods in this paper. The structures of APDS and intermediate products were characterized by Fourier Transform Infrared Spectroscopy(FT-IR), Differential Scanning Calorimeter(DSC) and Nuclear Magnetic Resonance Spectro meter('H-NMR). The curing agent APDS was synthesized by one-step and two-step methods. Meanwhile, the synthetic conditions of one-step and two-step methods, including reaction materials, reaction time, reaction temperature and reaction solvents were studied systematically. It was found that one-step was simple, reaction time was short and yield was high. The optimum reaction conditions of one-step were that benzene was used as solvent when reaction time was 8 hours, the reaction molar ratio of p-aminophenol and dimethyldichlorosilane was 1.8:1, reaction temperature was 70℃. The reaction mechanism of one-step method was also discussed.The curing techology conditions of APDS/CYD-128 system, the thermal properties and flame retardance of cured epoxy resins were studied seperately. The conclusions were as follows:(1) The curing temperature was 100℃, curing ratio (APDS:CYD-128) was 35:100 and curing time was 60min. These data were obtained by sol-gel method. (2) The best range of curing temperature was from 100℃to 130℃, the post-curing temperature was 153℃and the optimal curing ratio of APDS and CYD-128 was 35:100. These data were measured by Differential Scanning Calorimeter. (3) The thermal stabilities of cured system were also studied. The thermal degradation behaviors and the thermo-stability of the cured APDS/CYD-128 system were investigated with the themrogravimetric analysis(TGA), the char yield of 750℃and 800℃reached 36.20%,34.96%. (4) The flame retardancy of cured system was tested by LOI value. It was found that the LOI value of cured system could reached 31.6 when the curing ratio(APDS/CYD-128) was 35:100, and it was enhanced 63.7% comparing to the value of 19.3 of DDM/CYD-128. (5) The curing reaction kinetics were studied by the data which obtained by Differential Scanning Calorimeter, and the curing reaction rate equation was also acquired.