采用示差扫描量热分析技术,研究了一种环氧树脂粉末涂料与酚醛改性的该种涂料的固化反应机制和两种涂膜的交联结构,并结合两种涂膜在90℃蒸馏水中的静态浸泡实验结果,分析了涂膜交联结构对涂膜吸水性的影响。 结果表明:酚醛改性环氧粉末涂料的固化反应包括酚醛树脂与一部分环氧树脂的共聚反应,环氧树脂与固化剂的交联反应,以及少量酚醛树脂的自聚反应。而环氧粉末涂料的固化反应只有环氧树脂与固化剂-双氰胺的交联反应。酚醛改性环氧粉末涂料由于两种树脂的共聚交联反应,增加了体系的交联密度,提高了涂膜耐介质渗透能力。在高温下适当延长改性涂料的固化时间,能使两种树脂反应更充分,交联结构趋于完善,从而进一步提高耐介质渗透能力。
The chemical reaction processes occurring during the curing of epoxy powder coating and the phenolic modified epoxy coating were investigated. The structures of these two coatings were also studied and the effect of crosslinked structure on water absorption of coatings was examined by the static immersion testing in distilled water at 90℃. The results showed that the curing reactions of phenolic modified epoxy coating consisted the reaction between epoxy and curing agent, the copolymerization between phenolic resin and epoxy, as well as the polymerization of phenolic, while the curing process of epoxy coating only consisted of the crosslinking between epoxy and dicyandiamide. The cross-linked density in the mixture structure of epoxy and phenolic resins increased because of the crosslinking between the two resins. The resistance of this coating to medium permeation was enhanced. The curing time of phenolic resin modified coating should be properly extended at high temperature so that the curing reaction could be conducted thoroughly and the more ideal structure of coating for enhanced permeation resistance could be obtained.
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