Epoxy resins possess excellent comprehensive performance. Epoxy systems with latent curing agent have favorable storage stability

and have huge application demand and commercial value in adhesives

coatings

electronic packaging

composite materials and other fields. There are many kinds of latent curing agents. According to the chemical structure

latent curing agents include dicyandiamide

hydrazide

anhydride

benzoxazine and amino acid compounds

imidazole and modified amine compounds

boron amine complex and diazonium salt

iodonium salt and sulfonium salt compounds. In order to guide the design and use of latent curing agents

in this work

the reported latent curing agents are divided into three catalogues according to their different latent mechanisms

namely heat dissolving

chemical modification and microencapsulation

and their research progress is summarized and discussed. Meanwhile

the current evaluation methods of latent performance of curing agent are summarized

including DSC and rheological behavior analysis. Finally

the advantages and disadvantages of the current latent curing agents are evaluated

and the trends of future work are highlighted. Nowadays

the methods for achieving the latent performance are complex

and it’s still difficult to well balance the latent performance and storage stability for the latent systems. In the future

the one-component epoxy systems with long storage life at room temperature

and high curing speed at medium and low temperature

and favorable performance after curing should be focused; and the latent systems combined with other functions such as high performance

toughening

flame retardancy

energy conservation and environment protection should also be the development direction.