利用γ-氨基丙基三甲氧基硅烷(γ-APS)对环氧树脂分子进行改性合成了具有键合特性的活性树脂(γ-APS/EP),将活性树脂作为液态添加剂加入到环氧涂层中,利用活性树脂与金属表面羟基反应生成耐水解的噁烷键的特点,实现了环氧涂层/金属界面的化学键合。研究表明,活性树脂添加量为3% (质量分数)时,环氧涂层与金属基体的界面结合力和对腐蚀介质的抗渗透性能达到最佳。根据活性树脂含量的影响,提出了活性树脂在环氧涂层/金属界面的键合机理。

Epoxy coatings are widely used to protect metals from corrosion in ocean engineering and process industries. It has been proved that the adhesion between epoxy coating and metal is a key factor that affects their service life of the coating. However, interface between epoxy coating and metal substrate is usually combined by weak van der Waals force or secondary bond, which limits the protective performance of coatings. This work aims to translate the interface state from the physical adsorption to chemical bonding so as to increase the service life of epoxy coating. A kind of reactive resin γ-APS/EP with hydrolysis characteristic was prepared using γ-aminopropyltrimethoxysilane (γ-APS), and used as a coating filler with different contents of 0.5%~10%. Both dry and wet adhesion strength of epoxy coatings with different contents of γ-APS/EP were examined, the resistance to aggressive medium of epoxy varied with the contents of γ-APS/EP was evaluated by water absorption measurement, and the structure and composition of the coating/metal systems were characterized by using SEM, XPS, DSC and FTIR. The results showed that amino groups in γ-APS/EP disappeared and methoxysilyl groups (Si—O—CH₃) were remained after the synthesis process. Adhesion strength of the epoxy coating with metal substrate was significantly enhanced by introducing γ-APS/EP. Moreover, the dry adhesion strength of epoxy coating with 3%γ-APS/EP reached the maximum value of 12.4 MPa, which was twice the strength of pure epoxy, and was decreased with the content of γ-APS/EP further increasing. Meanwhile, wet interface adhesion strength of epoxy coating with 3%γ-APS/EP was still kept about 7.4 MPa after 900 h immersion in 3.5%NaCl, more than three times of pure epoxy coating. And also, epoxy coating with 3%γ-APS/EP showed the best performance with lower saturated water absorption. The chemical bonding can be obtained by the generation of oxane on the interface resulting from the reaction between the synthesized reactive resin and the hydroxyl on the metal surface after the reactive resin was added in the epoxy resin. Furthermore, the content of γ-APS/EP affected the number of chemical bonds at the interface, the hydrophilicity and the bulk density of coating. Finally, an interfacial chemical bonding mechanism was proposed.