With the development of UV LED curing technology, UV LED curing machines are more and more widely used, and they have been applied in many industries, such as the medical industry, microelectronics industry, and printing industry. UV LED curing machine has different precautions for different curing materials such as UV glue, UV ink, UV varnish and UV coating. So, what factors should be paid attention to when the UV LED curing machine is curing the UV coating?
In the curing process of UV coatings, by absorbing enough ultraviolet light energy, the "photoinitiator" contained in the inside is triggered to produce polymerization, cross-linking and grafting reactions, so that the coating will be cured in a short time. In order to ensure the complete curing of the coating, it is necessary to provide an appropriate amount of ultraviolet light energy. If the energy is too low, it may cause incomplete curing of the UV coating; and if the energy is too high, it will also have a negative impact on the UV coating, such as discoloration, cracking, or anti-curing reaction. Therefore, when using the UV coating curing machine, the energy must be controlled appropriately.
The thickness of the UV coating plays an important role in the effect of UV curing. If the coating is too thick, it will take longer to irradiate the UV LED curing machine with the same light power, which will not only affect the curing speed of the coating, but also easily cause the substrate surface temperature to be too high and cause deformation; if the coating is too thin, it will cause that the color of the surface coating deteriorates.
When the UV coating curing machine is in use, the distance between the irradiation head and the substrate will also affect the curing effect. The curing distance of different cured substrates is also different, most of the irradiation distance is generally controlled at about 10 to 15mm. If the distance is too close, it will cause thermal deformation of the substrate; if the distance is too far, it may cause incomplete curing, which will seriously affect the curing effect. Therefore, when using a UV LED curing machine, be sure to adjust the distance between the irradiation head and the bottom plate.
Different UV coatings require different curing time. Some UV glues can be cured within 5s, and some UV inks can be cured within 20s. This needs to be tested according to the actual situation to get the best Irradiation time.
The adhesion of UV coatings is also affected by the ambient temperature. Generally, the working temperature is between 15 and 25°. It should be noted that it cannot be exposed to sunlight for curing.