What is epoxy resin？

Epoxy resin is a kind of high molecular polymer, the molecular formula is (C11H12O3)n, which refers to the general name of a class of polymers containing more than two epoxy groups in the molecule. It is the polycondensation product of epichlorohydrin and bisphenol A or polyol. Due to the chemical activity of the epoxy group, a variety of compounds containing active hydrogen can be used to open the ring, cure and crosslink to form a network structure, so it is a thermosetting resin. Bisphenol A epoxy resin not only has the largest output and the most complete variety, but also the new modified varieties are still increasing and the quality is constantly improving.

Epoxy resins have secondary hydroxyl groups and epoxy groups, and the secondary hydroxyl groups can react with isocyanates. The epoxy resin is directly added to the hydroxyl-containing component of the polyurethane adhesive as a polyol. In this method, only the hydroxyl group participates in the reaction, and the epoxy group fails to react.
The carboxyl group of the acid resin is used to open the epoxy ring, and then react with the isocyanate in the polyurethane adhesive. It is also possible to dissolve the epoxy resin in ethyl acetate, add phosphoric acid for heating reaction, and add its adduct to the polyurethane adhesive, which can improve the initial viscosity, heat resistance and hydrolysis stability of the adhesive. Alcohol amines or amines can also be reacted to generate polyols, and the presence of tertiary nitrogen atoms in the adduct can accelerate the NCO reaction.
Using epoxy resin as polyhydroxy component combines the advantages of polyurethane and epoxy resin, and has good bonding strength and chemical resistance. The epoxy resin used in the manufacture of polyurethane adhesives generally adopts EP-12 and EP-13. , EP-16 and EP-20 varieties.