What are the main types of epoxy resin emulsions

What are the main types of epoxy resin emulsions? According to the classification of preparation methods, epoxy resin emulsions are roughly divided into three types: epoxy resin , self-emulsifying epoxy resin emulsions, and epoxy resin emulsions emulsified by curing agents.

(1) Add emulsifier type epoxy resin emulsion

Grind the epoxy resin emulsion to make micron-sized epoxy resin, and then add emulsifier for emulsification. The main factors affecting the stability of the emulsion are the nature of the emulsifier and the emulsification process, and the importance of the nature of the emulsifier goes without saying. The performance of epoxy resin emulsified by ordinary emulsifiers is not satisfactory, and special emulsifiers need to be synthesized. Most of them are synthesized by epoxy resin modified products, which are mainly the use of epoxy resin modified emulsifiers and bulk epoxy resins. The resin has an excellent structural similarity, so that the hydrophobic part of the emulsifier can be compatible with the epoxy resin to form a body, which not only improves the emulsification efficiency, but also hinders the migration of the emulsifier, so it can greatly improve the stability of the emulsion sex. Regarding the emulsification process, most of them use the phase inversion method in order to obtain an emulsion with small particle size and good stability.

Adding an emulsifier-type epoxy resin emulsion and adding an emulsifier accounting for 1% to 10% of the resin content can obtain a satisfactory emulsion. Compared with other types of epoxy resin emulsions, the cost is lower, and it has certain advantages in practical applications.

(2) Self-emulsifying epoxy resin emulsion

Introduce nonionic surfactant group (as epoxy vinyl group) on the main chain of epoxy resin, make each epoxy resin molecule have two or more than two epoxy groups, the epoxy resin of gained does not have to Adding an emulsifier can also be dispersed in water to form an emulsion, which is a self-emulsifying epoxy resin emulsion.

In addition, using medium and high molecular weight epoxy resins, using their more hydroxyl groups, using a certain amount of dibasic acid to esterify them, while retaining a certain amount of carboxyl groups, can also prepare self-emulsifying rings after being neutralized by ammonia. oxygen resin. But most of them are pre-type at present.

The advantage of self-emulsifying epoxy resin emulsion is that, firstly, there is no demulsification phenomenon; secondly, it can be ground into color paste together with pigments and fillers, so that the coloring part can be placed in the curing agent part and the environment. The oxygen emulsion part is more flexible. In addition, once the self-emulsifying epoxy emulsion has settled, the emulsion can be redispersed without special equipment. However, the cost of self-emulsifying epoxy resin is relatively high. Due to the introduction of other segments in self-emulsification, the physical and chemical properties of the resin (such as wettability to pigments, etc.) are greatly changed, and due to the non-ionic surfactant segment The attraction increases the water sensitivity of the coating film and reduces the corrosion resistance.

(3) Epoxy resin emulsion emulsified by curing agent

The emulsion obtained by emulsifying medium molecular weight and low molecular weight epoxy resin with emulsifier which has both curing function and emulsifying function. This is a promising class of epoxy resin emulsions. Emulsifier-type hardeners are less reactive overall. Thus prolonging the service life of the coating, and greater compatibility with epoxy resin, thereby improving the stability of epoxy resin emulsion and the uniformity of cured coating film.