Coating knowledge: Discussion on low temperature curing powder coating

Core tip: Although powder coating has the advantages of four "e" (economic, environmental, efficient and excellent performance), some of its weaknesses are also obvious If the curing conditions are harsh, the curing temperature is generally between 180 ℃ and 200 ℃ If the curing temperature can be reduced, the energy consumption can be reduced, which is the need of environmental protection, energy conservation and emission reduction High curing temperature, in addition to high energy consumption, can not withstand high temperature of some base materials, such as plastics Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Home of coatings: Although powder coating has the advantages of four "e" (economic, environmental, efficient and excellent performance), some weaknesses are also obvious If the curing conditions are harsh, the curing temperature is generally between 180 ℃ and 200 ℃ If the curing temperature can be reduced, the energy consumption can be reduced, which is the need of environmental protection, energy conservation and emission reduction High curing temperature not only leads to high energy consumption, but also limits the application of high temperature resistant base materials, such as plastics and wood, which greatly affects the expansion of powder coating application From the perspective of further improving the efficiency, the powder coating which can be solidified at low temperature can greatly shorten the curing time and improve the production efficiency under the condition of keeping the temperature unchanged Therefore, the realization of low temperature curing of powder coating has become one of the development directions of powder coating industry For a long time, with the efforts of colleagues engaged in powder coating and related supporting fields such as raw materials and equipment, the low-temperature curing of powder coating has made great progress Now pure epoxy system sand effect products can be cured at 130 ℃ / 15 minutes The surface high gloss epoxy system can be cured at 140 ℃ / 15 minutes However, the yellowing resistance and weather resistance of epoxy are poor, so it can not be used outdoors Compared with the epoxy system, the polyester / epoxy mixed system with better yellowing resistance can also be cured at 135 ℃ / 15 minutes, and the flat high gloss product can be cured at 150 ℃ / 15 minutes (with slightly poor leveling) The sand grain products of pure polyester system can be cured at 140 ℃ / 15 minutes, and the flat high light can be cured at 160 ℃ / 15 minutes However, it is still very difficult for the pure polyester system flat low light products at present It is very difficult to realize ultra-low temperature curing of powder coatings First of all, the curing system of powder coating is a kind of low-temperature latent curing system If the low-temperature reaction activity of the system is high, it will affect the extrusion and storage stability of powder On the other hand, the resin and curing agent used in powder coating are solid with high softening point, with high melting viscosity at low temperature When curing at low temperature, the coating film It is difficult to level, affecting the surface effect If the resin and curing agent with lower softening point are used, the melting viscosity can be reduced, but the storage stability of the powder is poor, which needs to be kept in cold storage at low temperature, which brings a lot of inconvenience to use Therefore, the key to prepare low temperature curing powder coating is to find a kind of resin and curing agent with high softening point and suitable reaction activity suitable for powder storage The development direction of low temperature curing powder coatings is to reduce the curing temperature of powder coatings The following aspects are discussed: making powder coatings for powder coatings and curing reaction of free radicals from the main resins, curing agents, catalysts, UV curing, UV curing and spray drying methods No matter thermoplastic or thermosetting, the film forming temperature of powder coating is about 180-200 ℃, and the curing time is long (10-20min), which limits that it can only be used for metal and other heat-resistant base materials, and it is time-consuming and relatively energy consumption In order to save energy and reduce cost, expand the coating range of powder coating, and better connect with solvent coating line, powder coating should be developed to low temperature curing type The low temperature curing of powder coating can be realized by reducing the melting temperature, viscosity, softening point, increasing the functional group of the resin, increasing the degree of crosslinking, adding appropriate additives, and using appropriate catalysts Reducing the curing temperature of powder coating can not only speed up the production of automatic production line and improve the production efficiency, save energy, but also greatly increase the application range of powder coating Home of coatings is 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