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Aromatic polyamide and its derivative coatings crosslinking agent
2017-8-20 23:51:11
Aromatic polyamide and its derivative coatings crosslinking agent
Aromatic polyamines and their derivative coatings have high reaction activity and excellent chemical resistance, but also have a very prominent yellow tendency. Another weakness is that the toxicity of aromatic polyamines and their derivative crosslinking agents leads to very suspicious physical activity.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Aromatic polyamines and their derivative coatings have high reaction activity and excellent chemical resistance, but also have a very prominent yellow tendency. Another weakness is that the toxicity of aromatic polyamines and their derivative crosslinking agents leads to very suspicious physical activity.
In other words, aromatic polyamide and its derivative crosslinking agents are difficult to resist the cross-linking agent of those systems required for environmental protection. Imidazole is a five-element heterocyclic compound with two nitrogen atoms, one of which is a secondary amine, and the other one is a tertiary amine.
The hydrogen activity on secondary amines is very high, causing the epoxy-opening ring. The hydrogen in the 2, 4 position of the midazole molecule can be replaced by a different group, resulting in a cluster of imidazole homologues. 2 - methymidazole and 2-phenymidazoline are the most commonly used crosslinking promoters in powder coatings.
Industrial product 2-methyl imidazole melting point 140? - 146? , the boiling point of 263? - 265? Activation temperature 82? - 87? (refers to the temperature that can produce crosslinking after 4 hours in 100gE - 51 epoxy resin). The appearance is light yellow to white crystal, often used as crosslinking accelerator.
It can be used as a promoter of dicyandiamide, dihydrazine, anhydride, phenolic resin and phenolic crosslinking agent. Generally, the amount of addition in powder coatings is 0.1% to 0.6%, and the dosage of catalyst for phenol crosslinking agent in heavy anti-corrosion epoxy powder coating is 0.6% to 1%.
The disadvantage is that the coating color can be yellowed easily and affect the storage period of powder coating to varying degrees. The imidazole addition is sometimes referred to as the addition of imidazole, the famous epi-curep101. It is A 1:1 or 1.5:1-equivalent ratio of 2-methymidazole and Epon828 liquid bisphenol A epoxy resin.
The imidazole addition can be used either separately or in combination with other non-catalytic crosslinking agents. Individual use can provide optimal low-temperature crosslinking performance, and other crosslinking agents can provide better application effects, so this cross-linking agent ACTS as a catalyst.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Uses:
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Uses:
The product is identical to Ethancure 100 and Lonza DETDA 80, DETDA is very effective polyurethane elastomer chain extender; also be used as polyurethane and epoxy resin curing agent, epoxy resin of an antioxidant, industrial oils and lubricants . In addition, also as intermediates in organic synthesis.Especially for the RIM (reaction injection molding), is important in the field of spray polyurea chain extender species. Also can be used for casting polyurethane elastomer (CPU) and a curing agent, epoxy curing agent, epoxy resin of antioxidants, lubricants and industrial oils other antioxidants.
And imidazole compounds, as to it simply as a promoter of powder coating is not appropriate, because it can reduce the storage stability of the powder coating and lead to serious agglomeration and eventually lose industrial applications.
Most of aliphatic and aromatic primary amine with secondary amine are solid at room temperature, but they cannot be used as a crosslinking agent in epoxy powder coating, because the system of high reactivity, in extrusion processing can cause many problems, also can significantly reduce the storage stability of coatings.
Several amine derivatives that have been developed can provide the necessary stability in the combination of powder coatings and solid epoxy resin.
Multiple amine is not belong to a polyol, but it in polyurethane synthesis with polyol up effect similar to that of strictly speaking the polymer obtained cannot be named pu, shall be referred to as poly (amino formamide or polyurea, however, as a people will usually polyurethane class discussion.
TGIC activity is poor, when designing coating formulation, we will consider selecting active polyester. And the hydroxyalkylamide itself is very reactive, and the reaction needs to be produced when the reaction is produced. If use the polyester neither reaction too fast to molten coating sufficient flow leveling time, also did not give response produced by the steam flow sufficient discharge time, so that a coating surface defects such as dim is not clear and the pinhole. Therefore, hydroxyalkylamide should choose polyester with poor activity.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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