1. Do a good job in ink balance control
In the offset printing process, the UV ink is weakly polar. If the ink balance control is not good, the emulsification phenomenon is easily caused, and the ink film becomes opaque, thereby directly affecting the transmittance of the ultraviolet light, thereby slowing down the curing speed of the UV ink. After the formation of the ink film, the interior thereof is still not fully cured. If the printed matter in this case is folded or rubbed or taped, the surface of the printed matter may be scratched or drawn on the surface of the printed product.
Therefore, controlling the ink-and-water balance during the printing process is one of the important factors to ensure the curing quality of the UV ink. Since the viscosity of the UV ink is large, the adhesion between the molecules is large, and the water resistance of the UV ink becomes strong. Therefore, in order to reduce the emulsification value of the UV ink, the principle of small amount of water must be grasped in the printing process, thereby Ensure that the printed products are brightly colored, the ink layer is thick, and the dots are clear and full.
2. Keep the temperature and humidity of the workshop suitable
During the printing process, changes in the temperature and humidity of the shop will affect the performance of the UV ink and substrate. For example, when the temperature of the shop is low and the humidity is high, the photocuring reaction of the UV ink is slow, and the ability to bond with the substrate is also reduced. Therefore, when printing with UV ink, the temperature and humidity of the workshop must be controlled within a suitable range. Generally, the temperature of the workshop should be controlled at 20 to 25 Â°C, and the relative humidity should be controlled at 50% to 65%.
3. Guarantee UV light intensity of UV lamp
First of all, it is an important prerequisite to choose a suitable UV lamp according to the printing speed and product type. The UV intensity of the UV lamp directly affects the curing time of the UV ink, which is also a key factor affecting the internal hardenability of the ink film. When the intensity of the ultraviolet light becomes low, even if the cumulative amount of light is increased by increasing the irradiation time, the hardenability inside the ink film cannot be improved, so that the UV lamp which exceeds the actual service life cannot completely cure the UV ink. Generally, the UV lamp is equipped with a timing device for the UV lamp. The actual service life of the imported UV lamp is about 1000 hours, and the actual life of the domestic UV lamp is about 600 hours. In order to ensure the curing quality of the UV ink, the UV lamp should be replaced in time after the actual service life is reached.
Secondly, if the ink contains impurities or dust in the production process adheres to the surface of the UV lamp, the intensity of the ultraviolet light is weakened, thereby greatly reducing the curing quality of the UV ink. Therefore, after the UV lamp is used for a period of time, the light box should be removed. Gently wipe the surface of the UV lamp with a clean, soft cotton cloth and dry ethanol to ensure it is clean and bright.
Finally, the reflector inside the UV light box can concentrate 80% of the UV light on the printed matter. If the paper powder or dust adheres to the reflector, it will affect the reflection of ultraviolet light. Therefore, in daily production, the reflector must be cleaned and maintained in time to maintain its best reflection angle and reflection capacity. This work can be done while cleaning the UV lamp, which is cleaned with a clean, soft cotton cloth filled with absolute ethanol. During cleaning and maintenance, the reflector should also be manually closed to check whether the closed state is intact. If necessary, check the integrity of the closing device. Generally, the closing device uses pneumatic components, which can be detected by electric eyes or electromagnetic. In addition, check the condition of the launching board. If the surface of the reflector is black or unsmooth, it should be replaced in time.
In addition, the purity and amount of pigments in the UV ink system, the arrangement of the printing color sequence, and the printing speed all have an effect on the curing of the UV ink.
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