| Schiff base metal complex is a novel kind of latent curing agent for epoxy resins. The cured epoxy has excellent heat resistance and mechanical properties.In this paper, a series of Schiff base metal complexes were synthesized and then used as latent curing agents for commercial DGEBA epoxy resin. The main contents include:(1) Two novel kinds Schiff base metal complexes have been synthesized by using salicylaldehyde, triethylenetetramine and Fe (Ⅲ), Cu (Ⅱ) metal salts as raw materials. The possible side reactions in the synthesis process have been discussed, and the most appropriate synthesis methods for these metal complexes have been identified. Elemental analysis, IR, NMR, and single crystal X-ray diffraction characterization showed that the synthetic products are target products.(2) Melting point, molar conductivity of [Fe(sal)2trien]NO3, Ni(sal)2trien, Cu(sal)2trien, Zn(sal)2trien metal complexes have been measured. According to the curing mechanism of metal complexes/E44syestem, we determine the amount of curing agent preliminarily. One-component metal complexes/epoxy resin/DMF resin syetems have been prepared. The storage stability of the resin system has been investigated by using gel time testing. The infrared spectra of each hardener/epoxy system (10/100molar ratio) at170℃for different curing time was tested and the curing process of each system was determined.(3) Heat resistance, glass transition temperature, dielectric properties, mechanical properties, insulation properties, water resistance of the schiff base metal complexes/E44systems have been studied comprehensively. The results show that Ni(II), Cu(II) and Zn(II) schiff base metal complexes containing epoxy polymers have better comprehensive properties than DDS/E-44and DICY/E-44system. While [Fe(sal)2trien]NO3/E44system containing free nitrate ions, all aspects of performance are poor, therefore, it is difficult to apply in the electronics industry.(4) Divalent metal Schiff base complexes/E-44systems were treated at250℃in air atmosphere for1h, then dielectric properties of them were measured and infrared spectra were characterized before and after heat treatment. The dielectric constant decreased to3.2-3.5range, the hydroxyl peak intensity decreases in the IR spectra of3430cm"1and carbonyl peak appears at1730cm"1after heat treatment, confirmed that hydroxyl group is oxidized to carbonyl group. In addition, the volume resistivity of each system which was immersed in95℃water for48h has been measured. Each system has excellent insulating properties. From the results we infer that the metal ions being chelated in the resin structure will not be free after treated at250℃in air atmosphere for1h. Epoxy cured by Ni(sal)2trien, Cu(sal)2trien or Zn(sal)2trien has excellent comprehensive performance, so they have important application prospects in the field of high-performance Lead-free epoxy copper clad laminates. |
PDF Full Text Request