Epoxy resin refers to a kind of polymer with more than two epoxy groups in the molecule. It is the Polycondensation product of epichlorohydrin with bisphenol A or polyol. Because of the chemical activity of epoxy group, a variety of compounds containing active hydrogen can be used to open the ring, curing and crosslinking to form a reticular structure, so it is a kind of thermosetting resin.Bisphenol A epoxy resin not only has the largest yield and the most complete variety, but also the new modified varieties are still increasing and the quality is improving.
01 material properties.
Epoxy resin has secondary hydroxyl group and epoxy group, and secondary hydroxyl group can react with isocyanate. Epoxy resin, as a polyol, is directly added to the hydroxyl component of polyurethane adhesive. By using this method, only hydroxyl participates in the reaction, and the epoxy group does not react. The epoxy ring was opened by acidic resin and carboxyl group, and then reacted with isocyanate in polyurethane adhesive. The epoxy resin can also be dissolved in ethyl acetate, the phosphoric acid heating reaction can be added, and the adduct can be added to the polyurethane adhesive.Heat resistance and hydrolysis stability can also be improved by the reaction of alkanolamine or amine to form polyol. Tertiary nitrogen atoms exist in the adduct, which can accelerate the NCO reaction. Epoxy resin as a multi-hydroxyl component combines the advantages of polyurethane and epoxy resin, and has good bonding strength and chemical resistance. Epoxy resins used in the manufacture of polyurethane adhesives are generally used in EP-12, EP-13, EP-16 and EP-20.
02 Market Prospect.
China is the largest and last piece of epoxy resin market in the world, and the prospect of China's epoxy market is very broad.
Epoxy coating (anticorrosion, anti-marine biological pollution). Experts predict that 40, 000 tons of marine coatings will be needed in China in 2000, most of which are epoxy anticorrosive coatings.
Container manufacturing industry continues to develop at a high speed, canned coatings need more and more epoxy resin.
Northeast China is bound to be a huge potential market for epoxy resin.
Waterborne epoxy coatings have a bright future. These two are the mainstream of the development of epoxy coatings. China is the fourth largest producer of powder coatings in the world and the largest producer of powder coatings in Asia. The Chinese government has identified powder coatings and waterborne coatings as priority for development in the future, and waterborne epoxy coatings play an important role in the waterborne coatings industry.
03 corrosion resistance.
As an anticorrosive material, epoxy resin not only has the characteristics of compactness, water resistance, good leakage resistance and high strength, but also has good technological properties such as strong adhesion, room temperature operation and simple construction, and the price is moderate. Anticorrosion works using such materials generally include: FRP integral surface layer and isolation layer supported by resin adhesive, block surface layer of resin cement and mortar, block surface layer of resin cement hook joint and grouting joint, Resin dilute cement or mortar made of a single and composite integral surface layer and isolation layer, resin glass flake cement surface layer and so on. If the selected materials are different, the final product function and application scope of anti-corrosion engineering will be very different.
04 material composition.
Epoxy resin anticorrosive materials are mainly composed of the following materials.
First, epoxy resin, refers to the polymer containing epoxy group, mainly suitable for corrosive media, alkali resistance is prominent, but also resistant to general acid (except hydrofluoric acid) corrosion.
The main characteristics of epoxy resin are high bond strength, low shrinkage, high brittleness and high price. The service temperature of epoxy resin cured at room temperature does not exceed 80 ℃.
The other is the curing agent of epoxy resin, including amines, anhydride, resin compounds and so on, among which amine compounds are the most commonly used.
The third is diluent, epoxy resin is usually diluted with inactive diluent.