UV cigarette packs offset printing problems

Offset printing process is currently a relatively mature printing process, especially in the level of printing, there are a set of standardized, data-based methods.

However, cigarette pack printing is not only a reproduction of product tones, it also involves a large number of spot color reproduction, such as a large area of ​​red field, gold and silver, pearlescent effects. Because spot colors, especially spot colors, have high requirements for saturation and brightness, offset printing is limited by the thickness of the ink layer when it is printed on the ground. In order to achieve the goal, the method of “deep first and then lightly” printing twice is usually adopted (design should be considered as possible to avoid emptying the text on the ground edition so as to avoid increasing the difficulty of overprinting). In addition, cigarette pack printing has higher requirements on the stability (consistency) of color. Offset printing ink is also relatively long due to the presence of ink emulsification. There are many factors affecting the stability of ink, and it is difficult to achieve the above requirements.

In order to meet the demand for high-grade cigarette pack printing, most printing manufacturers implemented UV process transformation on the offset printing press. The emergence of UV technology has fundamentally solved the problem of ink adhesion, friction resistance, and drying of composite paper printing products. The photosensitizers in the UV ink are exposed to UV light, the unsaturated bonds in the resin are opened, and cross-links form a network structure, which greatly improves the physical properties of the ink layer surface.

As a result, some cigarette pack manufacturers have begun to use offset UV inks to print fine sand, gold, silver and other common offset printing processes that are difficult to achieve. The PS plates, rubber rollers, and rubber blankets used in UV offset printing are different from normal offset printing. At the same time, the number of UV lamps, power, UV photosensitizer and other factors can affect the UV ink drying effect. In the arrangement of the color sequence, considering the different absorption of UV light by various colors, a printing sequence of white→black→cyan→yellow→red is often used. In addition, UV inks from different ink factories should not be mixed with each other. This should be paid special attention.