Five key technologies to realize flexible printing

Five key technical requirements for realizing flexible printing of high-speed corrugated paper

[China Packaging News] flexible printing of high-speed corrugated paper is a coordinated process of an integrated system, which requires the adjustment and mutual cooperation of all relevant links to achieve a relatively optimal value. For example, plate making, ink painting, corrugated paper and paperboard, printing equipment, printing technology and other links are very important and should be well coordinated. How to realize flexible printing of high-speed corrugated paper? The key technology is:

1 Determine the printing suitability conditions

first of all, understand the printing equipment. For example, the color number of the unit, the type and number of lines of the corrugated roller, the basic situation of the paper feeding system and the scraper system. There are also paper types, such as whiteboard or coated paper. If possible, a set of test plates for testing the printing suitability of the printer can be provided. It includes a ladder bar for testing the expansion of different line points of the flexo, a color block for measuring the field density value of the ink, a simple chromatography for overprinting different point proportions, yin-yang characters and straight lines of different font sizes, a module for measuring the chromatic error, a pressure bar for observing the printing balance pressure, and so on. The test printing plate is required to be completed under normal production conditions such as normal printing board, standard production water-based ink, normal printing pressure and speed. Of course, some printing conditions can be changed to get different test samples. Through the analysis of the social practice of the test specimen testing machine, we can get the printing suitability of this type of printing machine under normal conditions. The point expansion, curve, field density, hue value, point collision, influence of color sequence, reduction of fine lines, overprint error and printing balance pressure of each color can be obtained

combined with the test data obtained above and the printing effect of the test sample, a set of color matching management system for this printer can be established, such as establishing point compensation curve for point expansion, correcting screen color and gannina curve, color simulation and matching of proofing, etc

2. Determine the plate making process and color separation scheme

formlabs also announced the news of cooperation with 3shape. In plate making, the determination of color separation process scheme is a key factor, which plays a decisive role in the success of high-speed wire products printing to some extent. The color separation of flexible printing should use as few colors as possible and use as pure colors as possible to complete the superposition of colors, which is very helpful to printing and reduce costs

3. Selection of the number of lines and angles of the printing plate

the number of lines of the printing plate is restricted by the number of lines of the ink transfer roller, and the ratio between the two is required to be more than 1:5. The 400L/in corrugation roller can achieve a maximum of 80L/in printing plate. If the number of lines is too high, it is easy to paste the plate and produce moire. Therefore, the higher the number of lines, the better. Moreover, the printing effect of 80L/in and 75L/in will not be much different in terms of fineness

the addition angle of flexo printing mainly adopts two angles: 7, 37, 67, 82, and 7, 22, 52, 82 according to the angle of the corrugated roller. However, we should start from the actual situation of the product, not one size fits all. For example, for monochrome hanging linear patterns, the hanging angle must be 45 degrees or 0 degrees, otherwise there will be obvious jagged edges on the hanging patterns. The selection of overlapping pattern angle should be based on the principle that the hue angle of the main tone of the product pattern is 30 degrees different. For example, ELG and idasso jointly developed a light material for Chery electric vehicles. The skin of the portrait is mainly yellow, so the color difference between magenta and yellow should be more than 30 degrees; If the landscape is dominated by green tones, the color difference between cyan and yellow should be more than 30 degrees, otherwise moire will easily occur. Before plate making, conduct proofing simulation to determine the best addition method. Discrete points adopt certain additive technology, which increases the anti-counterfeiting of products

4. At present, the direct plate making system mainly adopts extremely high transfer technology, which can directly image on the resin plate after color separation and assembly. Digital printing plate has the advantages of complete dot type, extremely high light spots are not easy to lose, low printing dot expansion rate, step length, large dots, no paste and so on. It is the best choice for flexo high-speed plate making