Digital printing breakthrough direction

What are the breakthrough directions of digital printing in the label industry in terms of improving printing quality?

Almost all digital printing manufacturers admit that there is still a certain gap between the quality of digital printing and traditional printing. This may seem a bit like self-humility, but in fact, it is a way out for digital printing and traditional printing to judge the quality, and there is not enough confidence.

The author believes that there is no need to be humble, good is good, bad is bad, and self-humility is not good for competing for the market. We should rigorously and comparatively compare and judge the two major imaging modes of digital printing, namely electrostatic imaging and inkjet imaging.

(1) Electrostatic imaging adopts amplitude modulation network, and both electrostatic imaging processes of electronic ink and toner have their shortcomings. The unclean edges of the dots in toner electrostatic imaging are unique defects, similar to the emulsification of ink caused by large water in offset dots. Electronic ink is essentially a solvent-based ink, which is transferred by a blanket and its quality can be judged by the deformation of the geometric structure of the dots. Compared with traditional printing, digital printing using electronic ink electrostatic imaging has reached and partially surpassed the level of traditional printing, from the perspective of dot structure, not only the shape, but also the similarity, only in terms of color saturation and traditional printing is far away, especially compared with gravure printing.

Normally, digital printing uses a layer of black screen to trace colors, but the effect is not ideal. Because the saturation gap cannot be covered up by adding a layer of black mesh, hue darkening and saturation are actually two different ways to adjust. At this point, digital printing must throw in the towel.

(2) UV inkjet printing adopts frequency modulation mesh, and the minimum ink dot diameter is an effective way to judge the quality, the key is the difference between 1200dpi and 600dpi. The saturation of inkjet printing has been able to catch up with screen printing, especially in the combination printing of labels, the original use of screen printing for priming or surface glazing, or even partial glazing, has been replaced by inkjet printing in actual production. Inkjet printing adopts frequency modulation mesh, without the molar interference generated by multi-color overprinting, and the image appears very delicate and soft, but because the multi-color overprinting is used to form a clear and sharp dividing line at the edge of the pattern, the blurring of the dividing line is a unique defect of this printing process.

Inkjet digital printing with FM mesh is suitable for image printing of impressionist paintings, but not for fine gongbi paintings. In recent Asian Label Awards, many of the winning digital prints and pattern prints use the changes of light and shadow. I have the impression that there is a series of cultural and creative labels that use inkjet printing to interpret the style of well-known foreign oil paintings, which shows that the designer of the label is well versed in the essence of inkjet digital printing for pattern selection. UV inkjet printing has adaptability to images, which is a feature but also a limitation.

In fact, FM Network has also encountered a lot of embarrassment in the field of packaging and printing. First, traditional printing, especially packaging printing, does not use FM networks. This is because it is not easy to control the expansion of the outlets when repeating orders, which affects the stability of colors. FM networks are generally only used in the traditional printing field, such as pictorials, albums, etc. for one-time printing, and there are few printed materials. Because different batches of book editions are more tolerant of color difference. However, in the field of packaging and printing, it is difficult to bear this color difference, such as the spot color on the product packaging, especially the color of the logo, is the first element of the product packaging, and no one dares to take such a risk.

The second is the connection between short orders and long orders, if the amplitude modulation network is used, there is basically no technical difficulty. It should be noted that it is difficult to use electronic ink digital printing to chase traditional printing, as mentioned earlier, electronic ink electrostatic imaging to chase traditional gravure printing, but traditional printing chasing digital printing, as long as the ink amount is controlled during the printing process, the success rate will be extremely high.

Third, inkjet printing uses FM screen, color saturation is not a problem, but the digital printing of FM network and the traditional printing of AM screen will be very difficult in the connection, and prepress processing requires experience and skills. If the seamless connection is not achieved, the tragedy of the huge gap between the chromarolyn proofing of flexo printing and the actual printing more than 20 years ago may be repeated (the situation at that time was that the proofing quality of the FM network was comparable to photographic technology, which was very beautiful, but the actual printing of flexo printing was only 133 lines, and the minimum dot could not achieve 2%, which was not at the same level at all. Flexo finished products are chased by chromarolyn, no matter what method is used, the final result is still not the same). In the end, flexo printers can only laugh at themselves, and the proofing can only be seen, not counted, and the real proofing can only be on the printing press, laborious, and self-inflicted.

Here, I will introduce you to a case of traditional printing chasing digital printing. The 7th Asian Label Awards in 2020 won the championship according to the score, and it was originally a shrink sleeve printed with UV inkjet digital printing, but the label postponed the listing time due to the epidemic, so that the original work submitted by stepping on the point became an unlisted work to participate in the evaluation, and was pulled down according to the evaluation rules, missing the top award. Later, once the work was listed, the sales were hot, and the original process of UV inkjet digital printing could not complete the large number of orders in time, so the printing company used flexo printing to chase digital printing, and replaced the frequency modulation network of inkjet digital printing with flexo printing modulation net. Later, the flexo work participated in the national flexo printing quality evaluation of the Flexo Printing Branch of the China Printing Technology Association and won the Excellence Award of the label group. This work reflects the active cooperation between flexo printing and digital printing, opening up the market with digital printing without printing plates, completing orders with high-capacity flexo printing, and creating a new business growth point in the flexo printing industry.

It should be noted that flexo printing chases digital printing with conditions: first, use the AM network to chase the FM network, the key is the prepress of flexographic printing; second, successful follow-up requires exquisite skills; Third, this technology is difficult to replicate in large quantities and has limitations.

So, can traditional printing catch up with digital printing, and can digital printing successfully catch up with traditional printing? Here, we need to think about two questions first: first, flexo printing can actively cooperate with digital printing, and whether inkjet digital printing can be imaged with an amplitude modulation network from the beginning, which is seamlessly connected with the traditional printing behind; Second, when the network structure tends to be the same or consistent, digital printing and traditional printing can be similar from appearance to god, and when the two printing reach the same printing quality, is it necessary for digital printing to be humble that there is always some gap in quality?

In fact, for digital printing, inkjet digital printing using traditional amplitude modulation networks is not a new technology, and the Montai software that existed before the epidemic has such a function. Therefore, inkjet digital printing must not be satisfied with following the rhythm of foreign countries, that is, as long as it is inkjet printing, it must use the frequency modulation network. The author has not been clear about the original intention of foreign peers to love the FM network, just when Wenzhou conducted market research in June, Wenzhou users did not hesitate to say that they would choose the electrostatic imaging mode of electronic ink with a traditional network structure when choosing a digital printing machine, because the customer who issued the order liked it. This reason is very real, and it is worth doing a good study of the psychology and needs of customers in the industry.

According to the needs of customers, the improvement of inkjet digital printing machines is not difficult in the author's opinion. It can be considered from the following aspects:

(1) The improvement and upgrading of RIP of digital printing machine is an effective method for inkjet printing to use amplitude modulation screen.

(2) Compared with electrostatic imaging of electronic ink, the ink color of UV inkjet imaging is thicker and more environmentally friendly.

(3) UV inkjet digital printing using amplitude modulation screen will be achieved overnight with traditional printing. Therefore, this scheme will be reproducible in large quantities and is relatively stable and reliable.

It is necessary to remind friends of prepress technology that the current prepress technology is mainly keen on color management, and if part of the energy can be allocated to upgrade the RIP software of inkjet printing, it will be of great contribution to the entire printing industry chain, especially the label industry chain. In fact, there are also ready-made software abroad, which is more expensive, but for the subdivision of label digital printing, the improvement and upgrade of RIP, even if it accounts for 10% of the equipment price, is not impossible in this field. The key is not the price, but listening to the voices of users, including potential users. Labels actually reflect culture, the aesthetic concept of the Chinese market, the printing quality standards of Chinese enterprises, and the practical needs of Chinese users are all worth paying attention to. Users obviously need the structure of the outlets to be basically consistent with the color saturation, but the supplier stubbornly requires users to accept the color rendering of the FM outlets, emphasizing that the AM screen of traditional printing and the FM screen of inkjet digital printing are consistent in color, which is a bit ironic.

Finally, as an old printer, I would like to make two suggestions: first, traditional printing should take the initiative to embrace digital printing, use the automation of digital printing to drive the automation of traditional printing, and move forward at full speed towards the goal of intelligent traditional printing; Second, because flexo printing has found a way to break the game in terms of characteristic defects, and traditional flexo printing has occupied a favorable situation in greening and automation, and the distance from green and intelligent in the three traditional printing processes is the shortest, so as long as it seizes the opportunity of digital printing peers, its difficulties are the smallest.