Epoxy resins are generally used in conjunction with additives to achieve application value. Additives can be selected according to different uses, and commonly used additives include curing agents, curing accelerators, fillers, diluents, plasticizers and the like. Among them, the curing agent is an indispensable additive, otherwise the epoxy resin cannot be cured.
1. Curing agent. Commonly used epoxy resin curing agents are fatty amines, alicyclic amines, aromatic amines, polyamides, acid anhydrides, resins, and tertiary amines. In addition, ultraviolet light or light can also cure epoxy resins under the action of a photoinitiator. Generally, an amine curing agent is used for curing at room temperature or low temperature; an acid anhydride and an aromatic curing agent are commonly used for heating and curing; a latent curing agent is generally used as a curing agent for dicyandiamide.
2. Curing accelerator. In the epoxy resin, some substances added to accelerate the curing reaction, lower the curing temperature, and shorten the curing time are referred to as curing accelerators. Commonly used curing accelerators mainly include substituted phenols and some catalytic curing agents such as imidazoles (methylimidazole, 2-phenylimidazole).
3. Filler. The role of the filler is to improve some properties of the product, and to improve the heat dissipation conditions when the resin is cured. The use of the filler can also reduce the amount of epoxy resin and reduce the cost. Different fillers can be used depending on the application. The size is preferably less than 100 mesh, depending on the application.
4, thinner. Its role is to reduce viscosity and improve the permeability of the resin. Diluents can be divided into two categories: inert and active.
5, Plasticizer. Adding an appropriate amount of plasticizer can increase the fluidity of the resin, reduce the brittleness of the resin after curing, and improve the bending and impact strength. The varieties used are active plasticizers and inactive plasticizers. The commonly used active plasticizers are liquid nitrile rubber, polysulfide rubber, hydroxyl end polyether, etc. The commonly used inactive plasticizers are o-benzene. Dibutyl diformate, dioctyl phthalate, triphenyl phosphate, and the like.