Coating Science: Epoxy

Epoxy resin is a kind of organic macromolecule compound with two or more epoxy groups in its molecule Except for some, its relative molecular weight is not high The molecular structure of epoxy resin is characterized by the active epoxy group in the molecular chain, which can be located at the end, middle or ring-like structure of the molecular chain Because of the active epoxy group in the molecular structure, they can react with many kinds of curing agents to form insoluble and immiscible polymer with three-way network structure English term: epoxy resin refers to the polymer compound containing epoxy group in molecular structure The cured epoxy resin has good physical and chemical properties It has excellent bonding strength to the surface of metal and non-metal materials, good dielectric properties, small variable shrinkage, good dimensional stability of products, high hardness, good flexibility, and stability to alkali and most solvents Therefore, it is widely used in various departments of national defense and national economy for pouring, impregnation, laminating materials Adhesive, coating and other applications Epoxy resin has been studied since 1958 in China, and it has been put into industrial production at a very fast speed Up to now, it has flourished all over the country In addition to producing ordinary bisphenol-a-epichlorohydrin type epoxy resin, it also produces various types of new epoxy resin to meet the urgent needs of national defense construction and national development and economic departments Type 1: reactive hydrides react with epichlorohydrin epoxy resin mortar floor; 2 Hydrogen peroxide or peracid (such as peracetic acid) are used to oxidize double bond in liquid phase; 3 Air oxidation of double bond compounds; 4 Others Because its performance is not very perfect, at the same time, the application of epoxy resin is not the same According to the different objects used, the performance of epoxy resin is also required, for example, some require fast drying at low temperature, some require excellent insulation performance ------ Therefore, it is necessary to modify the epoxy resin in a targeted way: 1 Select curing agent; 2 Add reactive diluent; 3 Add filler; 4 Add other thermosetting or thermoplastic resins; 5 Improve the epoxy resin itself Characteristics 1 Various forms All kinds of resin, curing agent and modifier systems can almost meet the requirements of various applications Their range can be from very low viscosity to high melting point solid 2 Convenient curing With different curing agents, the epoxy resin system can be cured in the temperature range of 0 ~ 180 ℃ 3 Strong adhesion The existence of polar hydroxyl and ether bond in the molecular chain of epoxy resin makes it have high adhesion to various substances The shrinkage of epoxy resin is low and the internal stress is small, which also helps to improve the adhesion strength 4 Low contractility The reaction between epoxy resin and curing agent is carried out by direct addition reaction or ring opening polymerization of epoxides in resin molecules, without water or other volatile by-products.