Composition and Classification of Epoxy Resins

The epoxy resin adhesive has good bonding properties for various technologies and most non-metallic materials, and is often called "all-powerful adhesive". Widely used in aircraft, missile, automobile, construction, electronic appliances and wood processing and other industrial sectors, epoxy resin adhesive has the advantages of good technological performance, high bonding strength, small shrinkage rate, excellent dielectric resistance, good electrical insulation performance, but it is generally more brittle with poor impact resistance. As a result, commonly toughening agent is used to improve the performance.

1. The composition of epoxy resin

Epoxy resin is a polymer compound with two or more epoxy groups in the molecule and low relative molecular mass. An epoxy group is a three-way ring made up of one oxygen atom and two carbon atoms. Epoxy groups can react with free groups on the surface of the medium to form chemical bonds, so the adhesive force of epoxy resin is particularly strong. It has good adhesion properties for most materials such as wood, metal, glass, plastic, rubber, leather, ceramics, fibers and so on. It has poor adhesion to only a few materials such as polystyrene, polyvinyl chloride, celluloid, etc. Cured epoxy resin has excellent chemical corrosion resistance, heat resistance, acid and alkali resistance, organic solvent resistance and good electrical insulation. In addition, the shrinkage of resin after curing is small. For example, if appropriate filler is added, shrinkage can be reduced to 0.1% to 0.2%, and can be used at 150 to 200℃ for a long time, and cold resistance can reach -55℃.

Epoxy resin adhesive consists of epoxy resin, curing agent, plasticizer, toughening agent, accelerator, diluent, filler, coupling agent, flame retardant, stabilizer and so on. Among them, epoxy resin, curing agent, toughening agent are indispensable components, and others are decided to add or not according to needs.

2. The types of epoxy resin

There are many types of epoxy resins, which are constantly increasing. According to their chemical structure, they are classified as glycidyl ether epoxy resins, glycidyl esters, glycidyl amines, aliphatic epoxy resins, epoxy olefins, Hein epoxy resins, imide epoxy resins, naphthalene epoxy resins, organosilicone epoxy resins, organic titanium epoxy resins, etc. Glycidyl ether epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol P type epoxy resin, hydrobisphenol A type epoxy resin, phenolic type epoxy resin, bromine epoxy resin, aliphatic glycidyl ether resin, etc.