Also known as hardening agent, curing agent curing agent or stabilizer, is a kind of improve or control the curing reaction of a substance or mixture. Curable resin is through condensation, cyclization, or catalytic chemical reactions, the thermosetting resin process irreversible change curing is by adding crosslinking curing agent. Otherwise, not curing epoxy curing agent is essential additives, whether it is in adhesive, coating, casting material are required to add curing agent. The variety of curing agent has great influence on the mechanical properties, heat resistance, water resistance and corrosion resistance of the cured material..
Curing temperature and heat resistance of the curing agent
The curing temperature of various curing agents is different, and the heat resistance of the cured is also very different.. Generally speaking, the curing agent with high curing temperature can get the heat cured substance.. For the addition polymerization type curing agent, curing temperature and heat resistance as high in the following order: aliphatic polyamine < alicyclic polyamines < aromatic polyamine < phenolic < anhydride catalyst addition polymerization type curing agent of heat resistance generally in the aromatic polyamine levels. (tertiary amine and imidazole of antiquities) anionic polymerization, cationic polymerization type (BF3 complex) heat resistance are basically the same, which is mainly although the initiation of the reaction mechanism is different, but eventually the formation of ether bond network structure.
Curing reaction belongs to the chemical reaction and curing temperature effect, temperature increase, accelerate the reaction speed, shorter gelation time; gel time of numerical with the curing temperature rise is generally linear downward trend. But the curing temperature is too high, often make the properties of cured compound decreased, so there is the upper limit of the curing temperature; must choose the curing rate and the properties of cured compound compromise temperature, as a suitable curing temperature. According to the curing temperature of the curing agent is divided into four categories: low temperature curing agent, curing temperature below room temperature; room temperature curing agent, curing temperature to room temperature to 50 DEG C; moderate temperature curing agent for 50 to 100 DEG C; high temperature curing agent curing temperature of 100 DEG C. Belongs to the low temperature curing type curing agent varieties rarely, poly sulfur alcohol, polyisocyanate and so on; domestic development production of T-31 modified amine, YH-82 modified amine can be cured at the temperature below 0 DEG C. Many species belong to the type of room temperature curing: aliphatic amine, alicyclic polyamine; low molecular polyamide and modified aromatic amine etc.. Belong to the medium temperature curing type of a part of the aliphatic ring family polyamine, tertiary amine, and three boron fluoride compound. It belongs to the high temperature curing agent with aromatic amine, anhydride, A-stage phenolic resin, amino resin, dicyandiamide and acyl hydrazine.
For high temperature curing system, curing temperature generally divided into two stages. In front of the gel using low temperature curing, after in gel state or to a slightly higher than in the gel state, and then heated to a high temperature after curing (post-cure), relative to the previous segment curing for pre cure (pre-cure).