Plastic film flexographic printing process quality control

The flexographic printing inks used in ink plastic films are available at home and abroad. High-grade inks are still known for their foreign inks. The flexo printing inks of the 1980s are suitable for use in printed plastic vests (also known as pouches) for primary flexo presses (such as laminated flexo presses). In the 1990s, great progress was made in the flexo printing process of plastic films. Flexographic inks adapted to high speed, fineness, and high color were successively landed in the domestic market. Ink quality control, in addition to the perception of fineness, color viscosity and other parameters, the author thinks that the color concentration should be emphasized.
Flexographic inks, when printing fine flexographic plates, due to the use of high-line anilox rolls, even if the current anilox roll manufacturing process has undergone great reforms, CO2 laser engraving processes have been unambiguously named by YAG or others. With the laser replaced, the amount of strike ink has been significantly improved, but the anilox roller with a high number of screens also needs high-color ink, but it is still an indisputable fact. Many ink companies in their own production series, in addition to the general product, also specifically provide its ink, or high-density ink, is specifically designed to deal with this situation. However, if the ink used in normal production is overcharged, it exceeds a certain percentage, the resin in the ink is reduced, and the adhesion of the ink to the plastic film is inevitably reduced. Therefore, the ink is not as good as possible. To control a degree.
Choosing and controlling the color intensity of flexographic inks, the author believes that it is essential in process quality control. We feel that using a density meter to measure field density is simple and effective. However, the ink sample scraped on the film by the scraper bar is still different from the actual print process conditions (such as a certain number of lines of anilox roller, a certain density of double-sided adhesive tape, a certain printing speed). This difference must also be noted when the instrument is tested. In addition, when it comes to the residual amount of solvent in printed products, it should also pay attention to the resin used in the selection of flexo ink. Polyamide, nitrocellulose, and PVB have their own strengths, which cannot be ignored. The inks produced by foreign companies for printing on plastics have also been trial-controlled in the domestic market. I have tested such inks and have good performance, but there are still some problems. It is estimated that it will take time to fully replace alcohol inks.
The general printing and drafting enterprises do not produce their own drafts. The sales department handed over the electronic documents submitted by the customer to the technical department and then transferred it to a special plate-making company. The plate-making company could handle it. However, we often encounter a problem that is puzzling. The plates produced by the plate-making company according to the design in the electronic file are always unsatisfactory and sometimes have to be reworked.
Once there was such a thing, in the production of Coca-Cola 350ml “distribution” six cans of shrink packaging, the plates produced by the plate-making company according to the design in the electronic file were sent to Confirmation that it was rejected twice and successively reworked because the sent to the Palm was not approved by the advertising creative department. Customers do not confirm, where is the problem? After repeated analysis, we found the reason. Because of the heat-shrinkage PE film we use, the transparency is very poor and the product is printed on it. The whole feeling is not clear. In 2000, the design draft of the "Fanta" was orange-red. The emphasis was bright and lively, but now the product feels a gap.
Before sending the sample for the third time, the author went to the advertising company to communicate with the design department and chose one of the two different resolution manuscripts in the electronic file. Under possible conditions, the Fen drawn icon was fine-tuned. Because the lightness of the film is not enough, we have simplified the details around the icon in the design, highlighting the white part. White is the color with the highest brightness. With this part of the color, it can effectively mask the lack of film. Of course, when we printed, we printed two layers of white, which also made up for the lack of film. During the process of laying out the orange-red version of the cable, we clearly proposed a red net plus one percent based on the characteristics of the process. The printing plate produced by the plate-making company according to our above requirements was successfully printed and was soon confirmed by the customer.
In general, for the electronic documents transmitted by various printing companies, the plate-making company needs to make some adjustments, but this adjustment is mainly based on the adjustment of the compensation curve for network expansion and the compensation for the extension of the printing plate caused by the radius of curvature of the printing plate. For other parameters, it is generally determined according to the parameters in the electronic file. At most, in terms of deduction, some proposals for plate-making companies are recommended. However, in the actual printing process, there are various problems, such as clasps, 0.1mm can be done according to the printing technology of the satellite flexographic printing machine, but if it is not the printed plastic packaging, instead of the printed paper trademark, at this time dozens of The trademarks are put together into one piece, and there are no major or minor parts. For the trademark, the main part is everywhere, so the 0.1mm buckle can not take into account the overprint accuracy of the entire layout. In the past, when I was producing Tiger Brand Aluminizer trademarks, we had to put forward a series of specific requirements for the platemaking companies according to the characteristics of our company's equipment. In some places, the fasteners should reach 0.25mm, and some places should be left blank. Never stack. The shrinkage of the PE film during the printing process is also the same. The PE film, especially the PE of 25-40 [mu]m, shrinks very much during the printing process, and some products can reach 3% to 4%. This compensation for design manuscripts is essential.
This kind of parameter is unknown to the platemaking company. This requires the technical department to submit its own compensation requirements when submitting the electronic file. In addition, the adjustment of the layout is suitable for the flexographic printing process, such as the gradual change of the curve, large area on the ground. It is also necessary to take into account the separation of small plates from the plate making. In this way, product quality will be greatly guaranteed and delivery will not be delayed.
Therefore, the process quality control in the production process is to understand the design in the electronic file and adjust it according to actual production conditions. It is not just an electronic file that we hand over to the plate-making company. It must be a complete set of instructions. If you do not have a bottom in your mind at the moment, you should discuss with the technicians of the plate-making company and work out a better plan. We feel that the role of the technical department should not be just a setter, but should be a headquarters.