Flexographic plate prepress production notes

The socio-economic development and the improvement of people's living standards have begun to focus on aspects related to their own health, and care about the health effects of daily necessities, foods, and packaging products used in daily life. As a kind of environmental protection printing, flexographic printing has been applied more and more in packaging products in Europe and the United States, with a relatively large share. The products used in particular are products related to people's lives such as napkins and disposable cups.

Paper cups are one of the common household items. When people used to drink water from disposable cups, they would smell a pungent odor when they lifted their cups to their lips. Do you know why this is the case? Because in the past paper cups were printed by offset printing, the odor they smelled was the odor of offset ink; the offset ink itself contained harmful components to the human body. In the past, there was a case where domestically used offset printed packaging products were exported to foreign countries and the entire batch of goods was returned because they did not meet the foreign environmental protection requirements.

Now that you don't smell the pungent scent of a cup when you drink at KFC, it's because it uses flexo printing. Flexo uses environmentally friendly water-based inks, and water-based inks have passed the EU's environmental certification.

Of course, flexo printing has its own shortcomings. Because it is web printing, it is slightly inferior to offset in registering. Offset printing is usually done in four versions of Y, M, C, and K. Many small texts are overprinted with two or three colors. If flexographic printing also uses multiple colors to superimpose small text, the effect is certainly not good, so at this time, flexo printing can be made into spot colors for printing. This not only reduces the problem of overprinting, but also makes the text hue stable. With the two-colored small text, we can see that the text has two colors of edges due to overprinting problems.

Flexographic and gravure printing: Gravure printing can be used to create a gradient version of the field and mesh lines on a single plate. In the engraving process, the depth of the engraving plate can be used to achieve better results in the field and network lines. Flexo Printing If a large area of ​​the field and a large range of network cables are used together on a single plate, the two cannot be taken into account: Light pressure is required for the printing of the network cable, and a slightly larger pressure is required for the printing. If the network cable is printed, The actual part of the field is imaginary (not sufficiently thick); if it is faithfully printed, the outlet will be deformed too much.

We suggest that if you encounter the existing color pattern and the actual situation, you can divide it into two plates for plate making, and separate the plates from the color network lines in the field.

Flexographic printing is a type of printing between offset printing and gravure printing. Its ink layer is thicker than offset printing. In addition, it features: environmental protection printing; high color saturation; stable printing quality; flexible combination printing; And screen printing, offset printing, gravure line; bronzing, die-cutting unit processing to the finished product advantages.

The effect of a packaging printing product is good or bad because of its own design suitable for printing. Designing according to the characteristics of the flexographic printing method, the flexographic feature can be fully displayed before the flexographic product can be printed; for example, a multi-color spot color can be designed because the flexographic printing is based on the anilox roller and the ink is transferred, and only one net is used. The quantitative transfer of ink by the roller means that the amount of ink transferred to the printing plate during the printing process is basically the same. Compared with the ink transfer method of offset printing and gravure printing, the ink has a more stable and stable print quality.

Here are a few things to note about flexo prepress design.

Should avoid the following points: excessive fine text, small lines; two or more color overprint lines or text; small anti-white text or anti-white lines; picture high light off the net, or 1% of small outlets; In Photoshop software; design long and wide bars and fields in the horizontal direction of the printing cylinder; avoid long and wide gradient designs in the printing direction; large areas in the field with dots and small text on the same plane; operating software is not Unity, and so on.

There are also aspects to be noted in the design of the artwork format: As the design company often needs to operate some ideas in Photoshop, but it is necessary to adjust the image according to the characteristics of flexo printing before the flexo printing is made. If you have a layered file, it is best to save it in psd format; do not put the entire layout of the design, pictures and text at the same time into the Photoshop software; picture accuracy is not less than 300dpi; graphic design operation available Illustrator, Freehand professional Typography software.

Use Photoshop software to make the text come out with jagged edges. Take a look at the effect of the small anti-white characters printed out, and some of the text's strokes are pasted together. Designing a long, wide gradient along the printing direction is prone to ink bars.

Above, we list some designs that are not suitable for flexo printing. You can look at some designs that are more suitable for flexo printing.

The background color is a spot color on the ground. The dark color document above is directly imprinted on the background color. There is no overprint problem. The edges of the flowers are lighter in color, and there is no darker color resulting from the superimposition of the buckle.

The overall design uses four colors + spot colors, there is not much of the opposite color, due to suitable for flexo printing, so the overall printing out of the effect is very good. Reasonable process has a great influence on printing. Because more flexographic products are now transferred from the original offset or gravure, we also need to change in the process. The original design was designed according to offset printing. We performed color separations for the flexographic properties. The base image was completed with four colors, and the red color blocks and text were printed with spot colors. For flexographic printing, good or bad color separation also plays a key role in the printing effect.

Separation principle: whether it is close to the original; processing according to different printing characteristics; image contrast; image contrast, image authenticity;

Although flexo plates do not try to avoid netting, some products can also use net effect. Of course, this requires us to perform some technical processing on the images, so that the reversed colors of the printed products will not be changed by 3% of the dots. Darkness is not as hard as a normal broken network. Figure 7 is our use of network technology to make.

At present, 175 lines can be made from 1% to 97%, but we generally do not recommend that customers do too high network lines. On the one hand, the number of plate lines must be determined according to the anilox roller configured by the printing factory. From the author's experience, the difference in the number of lines within the 20 lines, usually there will not be too much visual difference, but the printing of India's resistance to force there is a big difference, such as the 175-line printing plate resistance to India will It is 40% less than the 150-line version; it is higher in terms of cost. On the other hand, from the point of view of the printed product yield, the image of the 150 line dot blocking ink will be less than that of the 175 line blocking ink, so the intangible yield is also high.

These are some of the author's technical experience, and share with your readers. All of the above products are printed using traditional flexographic printing, and the printing effect is similar to that printed using laser printing. At present, our company through some technical adjustments, allows users to use traditional flexographic printing to print close to the effect of laser printing.