Hardener - hardener cure temperatures and heat resistance
Various curing agent curing temperature varies, the heat resistance of the cured product is also very different. In general, the use of higher curing temperature curing agent can be cured product excellent in heat resistance. For addition polymerization type curing agent, curing temperature and heat resistance improve in the following order:
Aliphatic polyamine <; alicyclic polyamine <; aromatic polyamine phenolic ≈ <anhydride
Heat resistance generally catalyzed polyaddition type curing agent is an aromatic polyamine levels. Anionic polymeric (tertiary amines and imidazole antiquity), cation polymerization type (complex of BF3) is substantially the same heat resistance, although the reaction mechanism is largely different from the initial, but eventually form a network structure of an ether bond .
A chemical reaction of the curing reaction, the curing temperature by great temperature increased, the reaction rate increases, the gel time becomes shorter; values ​​with cure temperature rise of a generally straight gelation time decreased. However, the curing temperature is too high, often make the cured performance degradation, so the upper limit of the curing temperature of the existence; must be ed so that the curing speed and curing temperature performance compromise, as a suitable curing temperature. Press the curing temperature curing agents can be divided four categories: low temperature curing agent at a temperature below room temperature; room temperature curing agent at room temperature ~ 50 ℃; temperature curing agent is 50 ~ 100 ℃; high temperature curing temperature curing agent above 100 ℃. Belonging to low temperature curing agent species rarely curable, poly-sulfur alcohol type, type, etc. polyisocyanate; In recent years, the development of domestic production of the amine-modified T-31, YH-82 can be modified amine curing below 0 ℃. Part room temperature curing many types: aliphatic polyamines, alicyclic polyamines; low molecular weight polyamide and modified aromatic amines. Temperature curing type belongs to a part of alicyclic polyamines, tertiary amines, azoles Mi and boron trifluoride complexes. Belonging to high-temperature curing agents are aromatic polyamines, acid anhydrides, resol resins, amino resins, dicyandiamide and acyl hydrazide.
For high temperature curing systems, the curing temperature is generally divided two stages, prior to the use of low temperature curing gel, gel, or after reaching a state slightly above the gel state, and then heated at high temperature cure (post-cure), the relative before paragraph curing the pre-cured (pre-cure).