Discussion on the requirements of baking conditions for steel drum water-based paint
Text / Liu Shengbo Hu Yubing
Recently, I visited a number of barrel factories, thanked my friends for their warm reception, and witnessed the surface effects of different drying tunnels using water-based paint. To be honest, the surface effects of the same water-based paints after baking in different drying tunnels vary greatly.
Water-based paint manufacturers can adjust the formula according to the baking conditions of various manufacturers. However, in order to better control the product quality, smoother production and minimize the number of defective products, I would like to understand my understanding of the baking conditions of water-based paints. share it. I hope that experts will discuss and discuss!
First, why does the baking of water-based paint need to take the baking temperature before low?
1. The temperature in the front section is too high, the moisture evaporates quickly, and the viscosity of the coating increases rapidly, which tends to cause poor leveling.
2. It is well known that at standard atmospheric pressure, the boiling point of water is 100 °C. If the temperature in the front section of the drying tunnel is too high, causing the temperature of the water-based paint film to exceed 100 ° C, the water will become water vapor, resulting in an increase in the volume of the wet film. As a result, the thickness of the paint film increases sharply, and the macroscopic performance is loss of light and charring. .
Second, why is the hot air blowing directly on the top of the bucket not suitable for water-based paint?
The hot air blows directly into the top of the bucket. For water-based paints, there is another hazard besides the poor leveling and the loss of the paint film.
The hot air temperature is generally higher than 200 ° C. Under the hot air blowing, the surface of the wet film on the top of the barrel will exceed 120 ° C in a short time. This temperature is the crosslinking reaction temperature of the common amino baking varnish. At this temperature, the chemical reaction begins. The small molecules are crosslinked into macromolecules, and finally a dense coating film is formed on the surface.
As the baking progresses, the temperature of the undercoat of the paint film will reach the boiling point of water, and the liquid water will be discharged into gaseous water. However, since the surface of the coating film is about to form or has formed a dense paint film, water vapor is not easily discharged. The people began to fight each other. The final result was that the escaping bubbles formed pinholes after the surface of the paint film broke, and the unexhausted gas was fixed as bubbles in the paint film.
Since such a paint film contains a large number of pinholes and air bubbles, the structure is not dense, which inevitably leads to a decrease in the corrosion resistance of the coating film.
3. What are the special requirements for water-based paint on oven temperature?
At present, water-based paint has been applied in domestic barrel factories, and has been evaluated by many users. This not only solves the environmental problems of the spray booth, but also solves the environmental problems of the baking process, which saves the user's investment. It also saves the environmentally friendly finished products in the production process, but the baking requirements of water-based paints are different from the baking requirements of oil-based paints. Many steel drum companies believe that baking is not stressful, as long as the temperature required in the drying tunnel is reached. It can also be dried under the sun. It is not so simple. The drying requirements and temperature requirements of oil paints have been introduced in the Guilin meeting last time. However, most barrel mills do not meet the requirements, so the temperature of water-based paints. The distribution and temperature control requirements are different. It has a time requirement from the low temperature to the constant temperature in the temperature zone of the drying tunnel. The temperature zone also has time requirements, so the air volume distribution of the drying room is put forward higher. First of all, do you know that your drying room air volume distribution is adjustable? Is the temperature in each temperature zone controllable? Is the hot air in your drying room blown directly onto the bucket? Therefore, in order to use water-based paint, you must have a good baking equipment. Many companies have an understanding of our Huayu drying room, but only consider the price when investing, do not consider the use, do not consider the price. In short, I hope that when you invest, do not blindly pursue the low price, but also consider the beauty.
Medical Cosmetology Series,Medical Beauty Academy,Otc Cosmetology,Medical Beauty
Homesafe , https://www.homesafebio.com