Preparation Of The Colourless Transparent And Fast Curing Epoxy Adhesives

Application of epoxy resin adhesives are widely because they have excellent adhesive ability on a variety of materials and have the advantages of high adhesion strength, excellent electrical properties, low shrinkage, dimensional stability and good weathering resistance. The mix using of polythiol curing agents, tertiary amine accelerate and epoxy resin shows the advantage of colourness transparency and fast curing. So the polythiol curing agents have received extensive attention in recent years.Aimed to prepare excellent colorless transparent rapid curing epoxy resin adhesive, and ultimately to enlarge production, this paper is divided into the following four steps to start research work:1. Synthesis and process optimization of a multi sulfhydryl compounds.2. Preparation of the polythiol curing agent.3. Amplification of curing agent synthesis.4. Preparation of the colourless transparent and fast curing adhesive and the performance study.The firt step is synthesis of pentaerythritol-tetrakis-3-mercaptopropionate. A kind of drying agent A-10and a kind of composite catalyst were found to solve the problem of low esterification rate. Choosing mole ratio of3-mercaptopropionic acid and pentaerythritol between4to5, organic solvent G-10as the solvent. The best reaction temperature is between90to100℃. Put in the drying agent A-10in the end of the reaction, the keep reacting for1to2hours, After the separating and vacuum distillation, the purity of the product reached more than88%by testing.On the basis of the first step, pentaerythritol-tetrakis-3-mercaptopropionate is used to react with E-51epoxy resin in order to increase the viscosity of the curing agent and compatibility with epoxy resin. And finally makes the viscosity of884mPa.s (70℃) multiple mercapto colorless and transparent curing agent.The next step is finishing the amplification of curing agent synthesis in5L reactor to get the reference data for the industrial production. Optimized the process, the product performance is meet the standard by testing. The products’viscosity is874mPa.s(70℃). and the purity of the product reached more than87%by testing.The colorless transparent fast curing epoxy resin adhesive with excellent performance was prepared by the curing agent we prepared. The tensile shear strength, contact angle, UV-Vis light transmission, electrical properties and water absorption are tested, then calculated the surface energy of epoxy adhesive. The tensile shear strength is12.IMPa, surface energy is38.6mJ/m2, the maximal optical transmission is91.5%, water absorption is9.3%. It has higher tensile shear strength, lower surface energy, similar relative dielectric constant and UV-Vis light transmission compared with the J-13, it has a much lower water absorption than J-13.