Epoxy resin is a high molecular polymer with the molecular formula (C 11 H 12 O 3 ) n . It refers to a class of polymers containing more than two epoxy groups in the molecule. It is the condensation 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 and solidify and cross-link to form a network structure , so it is a thermosetting resin . Bisphenol A-type epoxy resin not only has the largest output and the most complete varieties, but also new modified varieties are still increasing, and the quality is constantly improving.

Epoxy resin has secondary hydroxyl groups and epoxy groups , and the secondary hydroxyl groups can react with isocyanates . Epoxy resin is directly added as a polyol to the hydroxyl-containing component of the polyurethane adhesive . Using this method, only the hydroxyl group participates in the reaction, and the epoxy group fails to react.

Use the carboxyl group of the acidic resin to open the epoxy ring, and then react with the isocyanate in the polyurethane adhesive . Epoxy resin can also be dissolved in ethyl acetate , phosphoric acid is added for heating reaction, and its adduct is added to the polyurethane adhesive, which can improve the initial tack, heat resistance , and hydrolysis stability of the adhesive. Alcoholamines or amines can also be used to react to generate polyols. The presence of tertiary nitrogen atoms in the adduct can accelerate the NCO reaction.