Waterborne epoxy resin refers to a stable dispersion in which the epoxy resin is dispersed in the form of particles or droplets in a dispersion medium containing water as a continuous phase. Room temperature curing of waterborne epoxy resin coating system. Generally can be divided into four categories. First introduced under the simple.

1, Ⅰ type waterborne epoxy resin system
The system consists of low molecular weight liquid epoxy resin (epoxy equivalent of about 190) and water-based epoxy curing agent composition. Epoxy resins in such systems are generally pre-emulsified and emulsified by aqueous epoxy curing agents prior to use, and such curing agents must be both crosslinking and emulsifying agents. Water-based epoxy curing agent synthesis is based on polyethylene polyamine, through the introduction of its molecules in the molecular role of the molecular segment, making it amphiphilic molecules. Can be well dispersed or dissolved in water, so as to have a good emulsification effect on low molecular weight liquid epoxy resin. Ⅰ water-based epoxy resin system has the advantage of being equipped with zero VOC paint, coating hardness increased faster. The disadvantage is that the resin used is a low molecular weight liquid epoxy resin, after the evaporation of water still need to go through a certain reaction time to achieve the surface dry; performance for the short period of application, about 2 ~ 4h system viscosity with the extension of time And the rapid increase; and within the scope of application system rheological performance is not stable.

2, Ⅱ type waterborne epoxy resin system
Ⅱ type waterborne epoxy resin system consists of high molecular weight solid epoxy resin emulsion and water-based epoxy curing agent composition. Epoxy resin is a lipophilic molecule with a hydrophilic-lipophilic balance (HLB) of less than 3. To obtain a stable aqueous epoxy emulsion, a surfactant having a surface activity such as polyoxyethylene polyoxypropylene chain And the molecular weight of the crosslinked chain was increased after the introduction of this segment, and the crosslinking density decreased, so the coating had some toughening effect. Most of the high molecular weight solid epoxy resin emulsions actually used are based on low molecular weight liquid epoxy resins using glycidyl ethers containing polyoxyethylene polyoxypropylene segments by bisphenol A chain extension and low molecular weight Epoxy resin reaction, the polyoxyethylene polyoxypropylene segments into the epoxy resin molecular chain, the product diluted with water and glycol ether can be a stable waterborne epoxy resin emulsion. As the epoxy resin in the type Ⅱ waterborne epoxy resin system has been pre-formulated into the emulsion, no water-based epoxy curing agent and then the epoxy resin emulsification, but only with the function of cross-linking agent. The curing reaction of the aqueous epoxy resin system is the reaction of the amine group in the molecule of the waterborne epoxy curing agent with the epoxy group in the epoxy resin molecule, while the low molecular weight epoxy resin has a low molecular weight epoxy resin. Type waterborne epoxy resin system is longer than the type Ⅰ, but at the same time also caused the coating to increase the hardness of the slow. Adding a small amount of film-forming additives can be good type Ⅱ water-based epoxy resin film forming performance, Ⅱ water-based epoxy resin coating system, once the water evaporation, even if the epoxy resin has not yet cross-linked curing has become a solid state, To achieve the requirements of the surface dry, so Ⅱ type water-based epoxy resin system will be relative to the dry time of the short.

3. Type Ⅲ waterborne epoxy resin system
Type III waterborne epoxy resin system consists of waterborne epoxy resin emulsion and polyurethane modified epoxy curing agent composition. Epoxy resin coating with high adhesion, good insulation properties, high hardness, but the formation of the coating flexibility and wear resistance is less than polyurethane coatings, so with the right amount of polyurethane modified epoxy resin, can be made comprehensive performance A good polyurethane modified epoxy curing agent, used to cure waterborne epoxy resin emulsion can improve the performance of waterborne epoxy resin coating. Polyurethane modified epoxy curing agent specific synthetic route for the polyurethane and polyether polyol first reaction, in the polyurethane molecular chain to introduce hydrophilic groups, the preparation of polyurethane prepolymer, and then the prepolymer and epoxy resin Grafting reaction, after the end of the reaction by adding triethylamine and salt, while in the water phase to expand and disperse.

4, IV type waterborne epoxy resin system
IV waterborne epoxy resin system consists of low molecular weight liquid epoxy resin emulsion and water-based epoxy curing agent composition, low molecular weight liquid epoxy resin emulsion is generally used to reverse phase technology. In order to overcome the shortcomings of the addition of low molecular weight surfactants to emulsify the epoxy resin, a new type of reactive epoxy resin emulsifier has been developed. By combining the molecular segments having a surface active action into the chain of the epoxy resin, the emulsifier molecule contains both a surface-active segment (hydrophilic segment) and an epoxy resin segment (lipophilic Segment), greatly improving the compatibility of emulsifiers with epoxy resin. The low molecular weight liquid epoxy resin emulsion having a dispersed phase average particle diameter of about 1 to 2 m can then be formulated with the emulsifier and by means of a phase reversal technique. At the same time, the reactive emulsifier molecular side also contains epoxy group, with water-based epoxy curing agent molecules in the amine reaction, after the film emulsifier molecules will not precipitate from the curing system, and the coating has a certain increase Toughness.