Consider the types and properties of curing agents: The types of curing agents have great influence on the mechanical properties, heat resistance, water resistance and corrosion resistance of cured products. For example, the heat resistance of curing epoxy resin with aromatic polyamine, imidazole, anhydride and other curing agents is higher than that of aliphatic polyamine and low molecular polyamide curing agents; the water resistance of curing epoxy resin with aromatic anhydride is better than that of aromatic diamine and aliphatic group. Polyamine curing agent; triethylenetetramine curing agent has good alkali resistance, but poor acid resistance and formaldehyde solution resistance. Resistance of epoxy resin cured with alicyclic polyamine (e.g. isophorone diamine) is excellent. The alkali resistance of epoxy resin cured by anhydride curing agent is better than that of acid resistance. Appropriate curing agents should be selected according to different applications and performance requirements.
Compound application of several curing agents: Several curing agents can achieve complementary effects. For example, low molecular weight polyamide curing agent combined with a small amount of m-phenylenediamine curing agent can not only cure at room temperature, but also increase the toughness of cured products while properly improving heat resistance. When TMA and methyl tetrahydrophthalic anhydride are combined, the eutectic mixture has low viscosity (25 C, 200-250 mPa. s). It is easy to mix with epoxy resin and improves the technological properties. The curing agent for injection is environmentally friendly. The selected curing agent should be harmless to human body and no pollution to the environment. Ethylenediamine can never be used as a curing agent alone. Modified amine curing agent should be used as far as possible.