What are the synthesis processes of epoxy powder coatings?

The synthesis process of epoxy powder coatings mainly includes the following steps:
Selection of raw materials: Epoxy resin is the main raw material of epoxy powder coatings, and its quality directly affects the performance of the coating. Therefore, attention should be paid to the matching of quality and performance when selecting. At the same time, it is also necessary to select suitable auxiliary raw materials such as curing agents, solvents, and additives according to different application fields and use environments. Batching: During the batching process, various raw materials should be accurately weighed out according to a certain ratio and added to the mixing equipment. During the batching process, attention should be paid to avoid the mixing of impurities and the generation of errors to ensure the quality of the coating. Mixing: Mixing is a key link in the synthesis process of epoxy powder coatings. The selection and operation of mixing equipment have an important impact on the quality and performance of the coating. According to the composition, proportion and properties of the coating, appropriate mixing equipment and operation methods should be selected to ensure uniform mixing. Spraying: Spraying is the last link of epoxy powder coatings. Before spraying, the substrate needs to be surface treated to ensure the adhesion of the coating to the substrate. During the spraying process, attention should be paid to the control of parameters such as spraying thickness, spraying distance, spraying speed, as well as the cleaning and maintenance of the spraying equipment to ensure the quality and stability of the coating. Specific synthesis method One-step solvent method: bisphenol A, epichlorohydrin and organic solvent are added into the reactor in a certain proportion, heated and dissolved, and then sodium hydroxide aqueous solution is added dropwise between 50 and 75°C to react. After the reaction is completed, the reaction temperature is raised to 85-95°C, kept warm for 8-9 hours, and then a large amount of solvent is added for extraction, and then washed, filtered, and the solvent is removed to obtain the finished product. The reaction temperature of this method is easy to control, the finished resin has good transparency, less mechanical impurities and gel particles, and a high product yield. Two-step method: The first step is to generate a diphenolyl propane chlorohydrin ether intermediate through an addition reaction, and the second step is to perform a closed-ring reaction in the presence of sodium hydroxide to generate an epoxy resin. The solvent is removed under high temperature and high vacuum conditions to obtain a pure solid epoxy resin.