水性环氧固化剂分散体的制备及改性

采用不同分子量的聚乙二醇与液体环氧树脂EPON828合成反应型乳化剂,然后将反应型乳化剂链段引入到以液体环氧树脂EPON828与间苯二甲胺为原料合成的端胺基中间体的分子结构中,再用活性稀释剂进行封端,最后加水分散,制得水性环氧固化剂分散体。采用了γ-氨丙基三乙氧基硅烷(即硅烷偶联剂KH-550)对其进行改性。确定了间苯二甲胺与环氧树脂EPON828的摩尔比为2.2∶1,聚乙二醇6000与环氧树脂EPON828(摩尔比为1∶1)制备的反应型乳化剂用量为9%,硅烷偶联剂KH-550的用量为固化剂分散体的质量的2%时,所制备的水性环氧固化剂分散体稳定性最佳,其粒径为750.8nm,固含量约60%,胺值为118mgKOH/g,黏度为4500mPa·s。室温固化后,涂膜硬度为3H,光泽度(60°)为108%,冲击强度50kg·cm,柔韧性1mm,附着力1级,耐酸碱腐蚀性能好。通过傅立叶变换红外光谱表征了反应产物。

Preparation and modification of water-dispersible epoxy curing agent

A reactive emulsifier was synthesized through the reaction of liquid epoxy resin EPON828 and polyethylene glycol (PEG) with different molecular weight, and then used as a chain extender to react with the amine-terminated intermediate prepared with EPON828 and m–xylylenediamine (MXDA). After the amine-terminated curing agent was end-capped with reactive diluent, a water-dispersible epoxy curing agent was obtained by adding water continuously. The water-dispersible epoxy curing agent was modified by silane coupling agent KH-550 (namely 3–aminopropyltriethoxysilane). The molar ratio of MXDA to EPON828 was determined as 2.2:1. The dispersion of waterborne epoxy curing agent, which was prepared using 9% reactive emulsifier synthesized with PEG6000 and EPON828 at an equivalent molar ratio and modified with silane coupling agent KH-550 with an amount of 2% of the dispersion, had optimal stability and following properties: particle size ca.750.8 nm, solid content 60%, amine value 118 mgKOH/g, and viscosity 4 500 mP·s. The coating cured at room temperature had a hardness 3H, 60° gloss 108%, impact strength 50 kg·cm, flexibility 1 mm, adhesion strength 1 grade, and good resistance to acid and alkali corrosion. The product was characterized by Fourier transform infrared spectroscopy.