[Chinese Packaging Network News] High-line corrugated flexible printing is an integrated system with the process, the need to adjust and cooperate with each other to achieve a relative best value. Such as plate making, ink painting, corrugated paper and cardboard, printing equipment, printing technology and other links are all very important and must be well coordinated. How to achieve high-line corrugated flexible printing? The key technologies are:
1. Determine printability conditions
The first thing to know about printing equipment. Such as the unit color number, the type and number of anilox rollers, the paper feeding system, and the basic conditions of the squeegee system. There are paper types, white paper or coated paper. A conditional test plate can be provided to test the printability of the printer. It includes a ladder strip for testing the expansion of different flexographic screen points, a color patch for measuring the density of ink in the field, a simple chromatogram for the overprinting of different dot proportions, a yin and yang character and straight line with different font sizes, and a module for measuring trapping errors. To observe the pressure balance of printing pressure bar and so on. Test plates are required to be completed under normal printing paperboard, standard production water-based ink, normal printing pressure, and vehicle speed. Of course, you can change some of the printing conditions to get different test samples. Through the analysis of the test sample, we can get the printability of this type of printing machine under normal conditions. The network expansion, curve, waterborne ink density, hue value, dot impact condition, color sequence influence, reduction of fine lines, overprint error, and printing balance pressure are available for each color.
Combining the test data obtained above and the test results of the control test samples, a color matching management system for this printer can be established, such as creating a dot compensation curve for screen dot enlargement, screen color correction and gannina curve correction, and color simulation of proofing. And match and so on.
2. Determine the plate making process and color separation scheme
In the flexo platemaking, the determination of the color separation process plan is a key factor. It plays a decisive role in determining the success of the high-line cable products. The color separation of the flexible printing is to complete the superposition of color with as little color as possible and as pure color as possible, which greatly contributes to the printing and reduces the cost.
3. Selection of printing plate screen lines and angles
The number of screen printing screens is limited by the number of screens of the ink transfer roller, requiring a ratio of 1:5 or more. The 400L/in anilox roller can achieve a maximum of 80L/in plate, and the number of lines is too high to paste and produce moire. Therefore, the higher the number of screens, the better. Moreover, 80L/in and 75L/in printing effects do not have much difference in terms of fineness.
Flexographic screen angles mainly use 7, 37, 67, 82, and 7, 22, 52, 82 angles depending on the angle of the anilox roller. However, the screen angle must be based on the actual product, and it cannot be cut across the board. If the monochromatic pattern is hung in a straight line, the angle of the hanging net must be 45 degrees or 0 degrees, otherwise the edge of the hanging pattern will appear more jagged. The selection of the overlapping pattern angle should be based on the principle that the hue angle of the main hue of the product pattern is different by 30 degrees. If the portrait is yellow, then the color difference between magenta and yellow should be more than 30 degrees; if the scenery is mainly green, then the color difference between cyan and yellow should be above 30 degrees, otherwise it will easily produce moire . Before the plate making, the proofing of screening is performed to determine the best screening method. Discrete outlets use a certain amount of screening technology to increase the security of products.
4. At present, the direct plate-making system mainly adopts extremely high transfer technology. After color separation and imposition, images are directly formed on the resin plate. Digital printing plates have the advantages of complete dot type, extremely high light spot not easy to lose, low print dot enlargement rate, long step adjustment, large dots, and no paste, and are the best choice for flexo high net line plate making.