High-line corrugated paper flexographic plate making and printing technology (2)

Update:14 Mar 2020
Summary:

2. Determine the plate making process and color separat […]

2. Determine the plate making process and color separation scheme
In flexographic printing plates, the determination of the color separation process plan is a key factor, which plays a certain role in determining whether the high-line product can be successfully printed. The color separation of flexible printing needs to use the least amount of color and the purest color to complete the color superposition, which is very helpful for printing and reduces costs.
Choosing the number of screen lines and angles
The number of screen lines of the printing plate is restricted by the number of screen lines of the anilox transfer roller, and the ratio between the two is required to be above 1: 5. The 400L / in anilox roller can achieve a printing plate of 80L / in at the highest, and the number of lines is too high, which is easy to paste and produce moire. So the higher the number of screening lines, the better. Moreover, 80L / in and 75L / in printing effects will not have much difference in terms of fineness.
According to the different anilox roll angles, the screen printing angle of flexo printing mainly adopts two angles of 7, 37, 67, 82, and 7, 22, 52, 82. However, the screening angle must be based on the actual product and cannot be a one-size-fits-all. For a linear pattern of a monochrome hanging net, the angle of the hanging net must be 45 degrees or 0 degrees, otherwise the edges of the hanging net pattern will have a more obvious jagged shape. The selection of the overlapping color pattern angle should be based on the principle that the hue angle of the main color of the product pattern differs by 30 degrees. If the skin of the portrait is dominated by yellow, the color difference between magenta and yellow should be more than 30 degrees; if the scenery is dominated by green, the color difference between cyan and yellow should be more than 30 degrees; otherwise, moire is likely to occur . Screen proofing simulation is performed before plate making to determine the best screen screening method. Discrete outlets use certain screening technology to increase the security of the product.
4. At present, the direct plate-making system mainly adopts extremely high transfer technology, and the image is directly formed on the resin plate after color separation and imposition. Digital printing plate has the advantages of complete dot pattern, extremely high highlight points are not easy to lose, low expansion rate of printing dots, long tone, large dots, and no paste, etc. It is the best choice for flexographic high screen line plate making.

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