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The drying of water-based paint is a very important issue to be solved in order to continue the development of the water-based paint industry. Under the pressure of the environmental storm in Guangdong, many furniture factories and wood products companies are considering using water-based paints. There are many drying methods for waterborne paints, and different drying methods have significant differences in the drying speed and film formation quality of waterborne paints.

Infrared drying is a very fast and low-cost drying method. Printed matter dried using infrared rays is stacked high and does not appear to be covered by the printed matter. Adhesion phenomenon: Infrared drying radiation is harmless to human health, and infrared drying does not cause the coating to solidify as quickly as external radiation.

What is the infrared drying method for water-based paints?

Infrared drying of water-based paints is the use of a light source that can emit energy within a very narrow wavelength range to heat a coating film that can absorb radiation within that wavelength range. The organic molecules in the coating absorb energy, promote the vibration or rotation of molecular atoms or groups, thereby increasing the energy inside the material, inducing physical and chemical changes in the material, and drying the coating.

Currently, infrared drying technology is commonly used for infrared drying, which can penetrate into the interior of the coating film to increase the internal temperature of the coating film. The internal temperature of the coating film is higher than the surface, causing the thermal diffusion of the coating film to form a temperature gradient from the inside out.

At the same time, there is also a moisture gradient inside the coating film that causes moisture movement. The interior with more water content gradually diffuses towards the exterior with less water content, consistent with the direction of thermal diffusion, thereby accelerating the drying process.

Infrared drying:

（1）The spectrum used for infrared drying can be divided into near infrared (wavelength 760-1400), mid infrared (wavelength 1400-3000 nm), and far infrared (wavelength 3000nm-1mm). The absorbed energy of infrared radiation decreases as the wavelength increases. Infrared curing has the advantages of fast temperature rise, fast curing speed, and good curing quality. However, due to the existence of temperature and moisture gradients, far infrared drying is not suitable for drying thicker coating films, and the thicker the coating film, the more obvious the gradient. In addition, infrared drying can only heat areas that can be irradiated by infrared rays, and a significant portion of the heat provided by far infrared rays is absorbed by the air, which also lacks a penetrating effect on the paint. It is not suitable for drying three-dimensional workpieces with complex shapes, and is generally used for drying the surface of objects.

（2）Medium wave infrared (MWIR) is a wavelength range commonly used for drying water-based paint coatings, and its penetration effect on coatings is much stronger than far infrared. Most of the light can penetrate the coating to reach the paper, and the drying effect is also very good, providing a truly efficient and economical heating method. Near infrared rays generate the highest energy and are rarely absorbed and scattered by air, making them suitable for heating thin coatings and paper.

In summary, selecting the appropriate infrared emitter can match the product and process based on wavelength, power, and emitter shape. In each case, the heating source should be selected based on the characteristics of the process and material. This ensures not only increased production speed, but also improved quality, while reducing scrap rates and saving costs.

Advantages of infrared drying

（1） Non contact heat transfer;

（2）High heat transfer capability.

（3）Efficient energy transfer through the use of optimal wavelengths;

（4）Due to the short response time, energy is only used when needed;