Type I waterborne epoxy resin curing agent is a modified product of polyethylene polyamine, and its synthetic technical route: using low molecular weight liquid epoxy resin and nonionic surfactant (indicated by BM) to generate terminal groups as epoxy groups The BM adduct is then added to the polyethylene polyamine to form an adduct that contains both a surface-active segment and an NH2 end group. In order to improve its compatibility with epoxy resins, the primary amine hydrogen is reduced. In order to extend the pot life of the waterborne epoxy system, the monoepoxy compound (aliphatic and aromatic) is reacted with the primary amine hydrogen to block part of the addition of the primary amine hydrogen and the monoepoxy compound. Therefore, it must also consider the hydrophilic and lipophilic balance so that it still has good water dispersibility. The method used is to add acetic acid to make it into a salt. This aspect can improve the closure of some primary amine hydrogen, on the other hand, it can be appropriately improved. Hydrophilicity makes the modified curing agent have a good hydrophilic-lipophilic balance.
Synthesis of waterborne epoxy curing agent: BM reacts with epoxy resin: epoxy 618 and BM (equivalent ratio 2:1) are reacted at 90~110C in the presence of a catalyst, and the epoxy equivalent epoxy equivalent is measured every 1h When the theoretical value is reached, the reaction is stopped.In the whole reaction process, both the temperature and the stirring speed must be controlled.Especially in the early stage of the reaction, the temperature will rise significantly due to the release of a large amount of heat. Try to cool it to avoid condensation. Synthesis of polyamine epoxy adducts: take the above product and react it with 2 equivalents of epoxy 618 and a certain equivalent of triethylenetetramine at 6080'C for 3 to 5 hours.After the reaction is completed, add water to dilute to solid content (quality Fraction, the same below) is 80%, and continue to stir for 0.5h for end-capping: control the reaction temperature to 60C, add a certain amount of butyl epoxypropyl ether (BGE) dropwise with a dropping funnel, about 0.5h drop
After completion, then continue the reaction at 60C for 1h to form a salt: slowly add acetic acid at room temperature, the salt formation rate is 20% due to the exothermic temperature of the reaction will rise, and then gradually decrease. Wait until the temperature drops to 50C and then heat it to control the reaction temperature at At 60C, keep the reaction for 1h and then add water at 60C to dilute to a solid content of about 50.0%. Continue to stir for 0.5h and then stop heating and stirring. The preparation of Type I water-based epoxy curable emulsion coating is as follows. Pour Type I water-based epoxy curing agent into a beaker, slowly add epoxy 618 under high-speed stirring, and continue to stir for 5 minutes after the addition is completed, that is, to form a Type I water-based ring Oxygen curable emulsion coating. The equivalent ratio of amine hydrogen to epoxy group is 1:1.