Synthesis And Properties Of Phosphorus-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 enviro-nmentally friendly. The halogen-free flame retardanted curing agents mainly included phosphorus-containing, silicon-containing and nitrogen-containing curing agents. Phosphorus-containing curing agent is concerned extensively due to its widely variety, high thermal stability and less smoke when it's burning.Firstly,2-(6-oxid-6H-dibenz<c,e><1,2>oxa-phosphorin-6-yl)chloride (ODC) was synthesized, and its structure was characterized by Fourier Transform Infrared Spectroscopy(FT-IR) and Nuclear Magnetic Resonance Spectrometer(1H-NMR). The synthesis of ODC include two steps, firstly phosphorodichloridate was prepared, then phosphorus heterocycles was synthesized in the second step which is the key step. Meanwhile, the synthetic conditions of ODC, including ratio of reactants, reaction time, amount of catalyst, reaction temperature were studied systematically. The results were shown that the reaction molar ratio of o-phenylphenol and phosphorus trichloride was1:1.2; o-phenylphenol melt at50℃,then phosphorus trichloride was added, and the mixture was heated6h at110℃.The mixture was heated at180℃,and maintained for8hours after0.4g AlCl3was added. Also the reaction mechanism of ODC was discussed at the same time.A novel acidic epoxy resin curing agent ODC-TA was synthesized from ODC and tartaric acid(TA), and its structure was characterized by FT-IR and'H-NMR. The synthetic conditions of ODC-TA, including reaction materials, reaction time, reaction temperature were studied by orthogonal experiment,and reaction solvents was also studied. The results shown that optimum reaction conditions of ODC-TA were that acetic acid was used as solvent when reaction temperature was110-120℃,reaction time was12hours, the reaction molar ratio of ODC and TA was2.5:1. ODC-TA was used as a curing agent in epoxy resins (CYD-128). The curing technology and the thermal properties of the cured system were studied detailly. The conclusions were as follows:(1) The curing temperature was100℃, curing ratio (ODC-TA:CYD-128) was45:100and curing time was45min. These data were obtained by sol-gel method.(2) The best range of curing temperature was from100℃to120℃, the post-curing temperature was153℃and the optimal curing ratio of ODC-TA and CYD-128was45:100. These data were measured by Differential Scanning Calorimeter(DSC).(3) The thermal stabilities of cured system were also studied. The thermal degradation behaviors of the cured system were investigated with the themrogravimetric analysis(TGA). The cured epoxy resin (ODC-TA/CYD-128=45:50) system exhibited5%weight loss at417.5℃and max weight loss at550.4℃, the char yield of750℃and800℃reached51.32%and50.04%. It was suggested that thermal stability of the cured producted has been significantly improved due to the rigid structure of ODC and pendant phosphorus group.A novel amine epoxy resin curing agent ODC-PA was synthesized from ODC and p-aminophenol (PA), and its structure was characterized by FT-1R and1H-NMR. The synthetic conditions of ODC-PA, including reaction materials, reaction time, reaction temperature were studied by orthogonal experiment. The results shown that optimum reaction conditions of ODC-PA were that methyl isobutyl ketone was used as solvent when the reaction molar ratio of ODC and PA was1.1:1. reaction temperature was110-120℃,reaction time was12hours.