环氧树脂是分子结构中含有两个以上环氧基团且能交联的一类 合成树脂。环氧基团是由一个氧原子和两个碳原子组成的环，即—C—C—/O，具有高度的活泼性，使环氧树脂能够与多种类型的 固化剂产生交联反应，形成三维网状结构的高聚物。环氧树脂的性能与分子量有重要关系：低分子量环氧树脂的硬度高，脆性大，冲击强度不高；线型环氧树脂附着力强，抗水性差，多用挥发型涂料；中分子量环氧树脂硬度，柔韧性适中。
Epoxy resin is a kind of synthetic resin which contains more than two epoxy groups and can be crosslinked. Epoxy group is a ring composed of one oxygen atom and two carbon atoms, namely - C-C - / O. it has high activity, which makes epoxy resin cross-linked with various curing agents to form a three-dimensional network polymer. The performance of epoxy resin has an important relationship with molecular weight: low molecular weight epoxy resin has high hardness, high brittleness and low impact strength; linear epoxy resin has strong adhesion and poor water resistance, so it is often used with volatile coatings; medium molecular weight epoxy resin has moderate hardness and flexibility.