How to make UV offset printing more advantageous

2022-08-07
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How to make UV offset printing more advantageous

uv offset printing products have incomparable advantages over traditional offset printing products in terms of surface texture, protection, wear resistance and production efficiency, especially for the printing of non absorbent materials such as plastic sheets, gold and silver cardboard. These advantages make those printing enterprises applying UV offset printing technology stand out from the competition. However, UV offset printing process is more complex. How do packaging and printing enterprises deal with the problems existing in the process of UV offset printing? How should packaging printing enterprises that intend to adopt UV offset printing be prepared

uv offset printing problem solving

to make UV offset printing work better, the main problems to be solved are as follows

1. Design plate making

the output format of the design draft for UV printing must be determined according to the work order, such as the forward or reverse scanning of the film surface, the number of output lines, line angle, etc. Some special printing pieces require higher resolution. For example, the resolution of 3D printing must be very high, and the line angle must match the printing material to avoid collision; Transparent plastic sheet and aluminized paper often need to be printed with white ink. Attention should be paid to the influence of printing material expansion and contraction, and the film should be corrected in advance to achieve the best quality

2. Adhesion

due to the poor permeability of substrates such as plastic sheet or gold and silver cardboard, the adsorption of ink is very weak. Therefore, even if UV ink is used for printing, the ink adhesion is very poor and the printing quality is not high. It can be solved by surface treatment of materials

3. Ink emulsification

uv ink has a narrow tolerance of water ink balance. It is easy to cause ink emulsification and dirty version in printing, which will affect the printing quality

solution: reduce the printing speed and control the printing speed at 5000 ~ 8000 prints/hour

4. Curing degree

in order to improve the color saturation of printed matter, when UV printing is carried out on the surface of substrate such as plastic sheet, the printing pressure is large, the ink layer is thick, and the dot increases seriously, which makes the ink difficult to cure. In order to ensure the printing quality, the printing pressure cannot be adjusted greatly. The solution is to reduce the printing speed, lengthen the UV lamp irradiation time, and let the ink solidify completely; The second is to adjust the distance between the UV lamp and the substrate, increase the intensity of UV light, and solidify the ink. The effective wavelength range of UV curing is 200 ~ 400nm, and the wavelength of some light sources in the printing workshop is also within this range, which will cause slight curing of the ink surface. Therefore, attention should be paid to the impact of ambient light on UV ink

5. Color sequence arrangement

uv offset printing color sequence arrangement is complex. Due to the limitation of inking principle, the ink layer on the substrate is thin. When it is necessary to select a thicker ink layer than how to select a single arm tensile testing machine, it is difficult to achieve the desired replication effect. For example, in four-color overprint, the commonly used printing color sequence is black, cyan, magenta and yellow. Because black almost occupies all the space, the inking power of cyan, magenta and yellow is lower, and the total amount of ink is not enough, the color will not be full

solution: change the color sequence, first print the color with a small amount of ink, and finally print the black with a large amount of ink, so as to maximize the ink amount and make the color fuller

6. Printing registration

uv offset printing uses UV lamp to cure the ink. The main problem caused by curing is that the substrate is heated and expanded, resulting in inaccurate overprint. This is in contradiction to UV ink curing, because ink curing requires a longer UV lamp irradiation time, which can effectively meet the impact resistance test requirements of explosion-proof equipment, while the printing set requires a shorter UV lamp irradiation time

solution: UV curing shall be carried out after the last color printing. At this time, even if the substrate expands, the operating environment can be reduced by placing it for a period of time: low temperature, and the continuous production of prepreg semi-finished products will stop for a period of time to minimize the substrate deformation. Under special circumstances, the intermediate color group can also be illuminated with UV lamp, but the shorter the irradiation time, the better. Alternatively, cold UV technology can be used

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