Powder coating curing temperature and time and coating effect

Update:14-08-2020
Summary:

The powder coating itself is only a semi-finished produ […]

The powder coating itself is only a semi-finished product, and only after spraying and curing can it become the final product. Consumers only pay attention to the effect and quality of the coating, which means that the use of powder coatings is as important as the production of powder coatings. Low-quality powder No matter how good the spraying equipment, no matter how meticulous the pretreatment, and no matter how strict the painting process, high-quality products will not be produced; no matter how good the quality of the powder is, there will be no high-quality products if there are problems with the spraying equipment, process and pretreatment However, the reality is that most of the attention of domestic coating companies is on the powder coating products themselves. When there are quality problems, they only look for problems in the powder. However, there is not enough attention and research on the coating construction process, which makes a large number of coating products unable to meet the application. Some effect.

 

Each powder coating has its own curing characteristic curve, which can achieve complete curing within a certain temperature and time range. In order to improve efficiency and reduce costs, it is against the law to shorten the curing time. If the curing temperature or time If it is not enough, the curing will be incomplete, the proper performance will not be exerted, its physical properties will be greatly reduced, the chemical resistance will not be good, and the decoration, corrosion resistance and weather resistance will not reach the expected results. Even if some coatings cured at low temperature are completely cured, they are not as good as those cured at high temperature. Especially for some workpieces formed after curing, small cracks will be formed at the stamping and bending parts, and moisture will penetrate along the cracks. , And quickly corrode the base material. We can see that the traffic barriers used outdoors will show signs of rust at the arc corners of the intersection soon after being put into use. This is related to the baking temperature and time and the bending after spraying. Direct relationship.

Some people think that the heating temperature is lower, the reaction speed is reduced, and the leveling can be better. In fact, it is the opposite, because after powder spraying, its melting and solidification are carried out almost at the same time. The heating is rapid, the temperature rises quickly, and the viscosity of the system decreases rapidly. The leveling process has been completed before gelatinization, and this kind of board has good leveling and less orange peel. At the same time, the coating can wet the surface well, improve its adhesion, and has better durability. Due to the rapid curing, the internal stress of the film layer will be more, but because the coating film is thinner, the physical properties have little influence. On the contrary, if the heating is slow, the viscosity of the system always maintains a higher level. At this time, the curing has already begun. As the reaction proceeds, the viscosity continues to rise, and the leveling effect will not be good.

 

In short, if you want to heat quickly and reach the curing temperature in a short time, you can get the ideal coating effect and long-term protection function. If the heating temperature is low and the time is too long, the powder coating will melt, level and wet the coated object. The curing effect occurred before, and the physical properties are not ideal. At the same time, the volatiles are difficult to escape, which leads to the premature damage of the coating under corrosive conditions, and the decorative and protective properties are not reflected.

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