The curing agent can be divided into the curing agent at normal temperature and the curing agent according to its use. High temperature curing epoxy resin is excellent performance, but used in civil construction in coating and adhesive because of difficult heating, need room temperature curing; so most of the use of aliphatic amine, alicyclic chiral polyamide and especially, coating and adhesive used in winter had to do with polyisocyanate and use, or use a Mephitical poly Okinawa alcohol.
As for medium temperature curing agents and high temperature curing agents, they should be selected on the basis of heat resistance and heat resistance, adhesion and drug resistance of cured products. The emphasis is on polyamines and anhydrides. As the acid anhydride solidified material has excellent electrical properties, it is widely used in electronic and electrical fields.
The aliphatic polyamines have good adhesiveness, alkali resistance and water resistance. Aromatic polyamines are also excellent in drug resistance. As the amino nitrogen elements and metals form hydrogen bonds, it has a good antirust effect. The higher the concentration of amine, the better the antirust effect. The acid anhydride curing agent and epoxy resin form ester bonds, which show high resistance to organic acids and inorganic acids, and the electrical properties generally exceed the polyamines.
The curing temperature of various curing agents is different, and the heat resistance of the cured material is also very different. Generally speaking, a good curing agent can be obtained by using a curing agent with high curing temperature. In addition polymerization type curing agent, curing temperature and heat resistance increased in the following order: aliphatic polyamine < <; alicyclic polyamine; aromatic polyamine is phenolic anhydride with catalytic < heat resistant polymer curing agent in aromatic polyamine levels in general.
Anionic polymerization type (tertiary amine and imidazole of antiquities), a cationic polymerization type (BF3 complex) heat resistance are basically the same, although this is mainly different reaction mechanism of initiation, but eventually form a network structure with ether bond, curing reaction is a chemical reaction, by the great influence of curing temperature, the temperature increases, the reaction speed accelerate the gelation time shortened; gelation time on the value with the curing temperature rising is roughly linear downward trend.