The curing agent can be classified into a room temperature curing agent and a heating curing agent according to the use. Epoxy resin generally has excellent performance when cured at high temperature. However, coatings and adhesives used in civil engineering are difficult to heat and require room temperature curing. Therefore, most of them use fatty amines, alicyclics, and polyamides, especially in winter. Coatings and adhesives have to be used in combination with polyisocyanates or with odors of polysterols.
The medium-temperature curing agent and the high-temperature curing agent are selected based on the heat resistance of the object and the heat resistance, adhesion, and chemical resistance of the cured product. The choice is focused on polyamines and anhydrides. Since the anhydride cured product has excellent electrical properties, it is widely used in electronics and electrical appliances.
The aliphatic polyamine cured product is excellent in adhesion, alkali resistance, and water resistance. Aromatic polyamines are also excellent in chemical resistance. Since the nitrogen element of the amino group forms a hydrogen bond with the metal, it has an excellent rust preventing effect. The higher the amine mass concentration, the better the rust prevention effect. The acid anhydride curing agent and the epoxy resin form an ester bond, exhibit high resistance to organic acids and inorganic acids, and generally have electrical properties superior to polyamines.
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