The performance of epoxy resin coating varies greatly with the type of curing agent, mainly in the following aspects:
(1) Improve the mechanical properties of epoxy resin coatings.
The epoxy resin coating has high reactivity and high crosslinking density, so the coating film has good corrosion resistance. However, there are also insufficient physical and mechanical properties, such as poor elasticity and high brittleness, which can be improved by introducing curing agents with flexible segments, such as polyamides with long-chain fatty acids.
(2) Improve the process performance of epoxy resin coatings.
Epoxy resin coatings are often applied on-site on a large scale, and there are problems with the toxicity of volatiles and the operability in humid and low temperature environments. In recent years, a variety of non-toxic or low-toxic modified curing agents, such as modified ketimine curing agents, have been developed with excellent workability, mechanical properties and corrosion resistance.
(3) Improve the corrosion resistance of epoxy resin coatings.
The corrosion resistance of different epoxy curing systems is also quite different. The epoxy resin cured by the amine curing agent has good alkali resistance but poor acid resistance, because the tertiary amine structure formed after curing is easy to react with acid to form tertiary ammonium salt. The epoxy resin cured by acid anhydride curing agent is just the opposite. It has good acid resistance and poor alkali resistance, because the ester group formed after curing undergoes irreversible hydrolysis under alkaline conditions.
(4) The temperature resistance of the epoxy resin coating.
The epoxy resin cured with aliphatic amine curing agent has a lower heat distortion temperature, usually only 70~80℃. The use of a suitable aromatic curing agent or acid anhydride curing agent can increase the heat distortion temperature to about 150°C, but the latter two curing agents generally need to be cured under heating when used alone.
(5) Improve the dielectric properties of epoxy resin coatings.
When epoxy resin is used for insulating coatings, an improved copolymer of trimellitic anhydride can be selected as the curing agent, which can significantly improve the heat resistance and dielectric properties of the coating.