Matters needing attention in color box printing
1. Problems related to design
When using an offset press to print corrugated box paper, the following points should be paid attention to in design:
(1) The density distribution of the continuous tone pattern should be uniform, and the hanging angle should be distinguished by color.
(2) If there is a large area of solid overprinting, do not design small patterns or words overprinted in the same color.
(3) Avoid designing long strips along the printing direction, so as not to cause the surrounding blank parts to be affected by the printing color of the strip edges under the inking action of the inking roller.
(4) Avoid designing large areas of dark tones.
(5) The bar code should not be overprinted in the design. Note that the bar code should be located on the back or side of the carton after the box is formed.
2. Printing failures related to offset presses
When printing corrugated box paper with an offset press, there are many printing failures related to the offset press, which can be summarized as follows:
(1) Overprinting is not allowed
There are many reasons for inaccurate overprinting, such as insufficient overprinting accuracy of the machine and loose plate clamps. If you want to print color boxes, you might as well go to contact Bookprintingchina, who is a professional China printing company with more than 20 year printing experience.
(2) Water bar, ink bar
Generally, it is caused by the uneven contact pressure of the water roller and the ink roller.
(3) The dots are enlarged or reduced, or even lost.
(4) Sticky Dirty Flowers
Due to the high quantitative weight of corrugated box surface paper, generally above 180g/m2, high stiffness, poor winding, but strong rebound, it is easy to produce sticky, dirty and flowered phenomenon. Therefore, it should be positioned according to the die-cutting position in the printing unit. Anti-scratch device, if necessary, a sponge pad can be added to the part where there is no ink or little ink on the paper feeding roller.
3. Printing failures related to ink
(1) The ink viscosity is not suitable
The viscosity of the ink is too low, it is easy to paste the plate during printing, and the water supply must also be increased. During the transmission, the water roller will also stick the ink on the plate cylinder back, making the fountain solution dirty. The viscosity of the ink is too high, and the inking is difficult, especially the mesh tone can not be printed, even if the ink volume is increased, the effect is not obvious, and the printed matter is prone to sticking.
(2) The printed matter is easy to fade
When printing corrugated box paper, high-gloss wear-resistant ink should be used to ensure that the printed pattern can withstand frequent handling and friction during transportation.
(3) Prints dry too slowly
This has a lot to do with the ink adjustment. When printing a large area, if there are too many lipids in the ink, the lipophilic and lipophilic properties of the paper fibers will affect the volatilization and drying of the additives. Moreover, the large area after printing often needs to be varnished, which is even more unfavorable for the drying of the ink. In addition, in the season of high temperature drying, drying oil should not be used too much, and part of drying oil can be replaced by anti-adhesive agent, and the amount of powder spraying should be appropriately increased to prevent sticking, which may bring trouble to the subsequent lamination process, but lamination The powder removal process can be temporarily added.
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