The hottest mainstream digital printing technology

2022-08-13
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Mainstream digital printing technology

release date: Source: China paper industry

today, as we enter the era of short version rapid printing, digital printing technology has become more and more popular. However, the development of digital printing in China is not plain sailing, during which there are still many obstacles. Although digital printing is also gradually maturing, its proportion in China's total printing business is not high. On the one hand, because the overall price level of domestic offset printing is lower than that of Digital Express Printing, the advantages of digital printing in price and production cycle have not been fully brought into play. At the same time, the advantages of digital printing personalized printing have not been fully developed, and many people are still vague about the concept of digital printing; On the other hand, there are still some differences between digital printing and traditional printing products, so people have misunderstandings in product identification and printing demand, which also lags behind the development of digital printing in our country. On the whole, digital printing has become increasingly popular in China since 2004, but it is only in its infancy, and many people still have doubts and confusion about it. China paper introduces several mainstream digital packaging printing technologies in order to let more people know about digital printing technology

1. The concept of digital printing

digital printing, in a broad sense, any device connected to a computer that can print directly without plate making can be called digital printing. In the narrow sense, digital printing is a new printing technology that uses the prepress system to transmit the graphic information directly to the digital printing machine through the network to print color prints. At present, several mainstream digital printing technologies mainly include inkjet imaging, electrostatic imaging, magnetic recording imaging, direct imaging (DI) and electrocoagulation imaging

2. Several mainstream digital printing technologies

(1) ink jet imaging digital printing

ink jet printing refers to shooting the ink from the micro nozzle to the substrate at a certain speed, and then realizing the ink image reproduction through the interaction between the ink and the substrate. Its imaging principle is to shoot the ink from the micro nozzle (generally 30-50 in diameter) at a certain speed μ m) Spray it on the substrate, and finally realize the reproduction of the ink image through the interaction between the ink and the substrate. Generally, it is required that the solvent and water in the ink can quickly penetrate into the substrate to ensure sufficient drying speed, and the colorant in the ink can be fixed on the surface of the substrate as much as possible to ensure sufficient printing density and resolution. Therefore, the ink used must match the substrate to ensure good printing quality. The early equipment mainly used continuous ink-jet, and the nozzle dripped ink continuously according to a certain law. If the dripped ink did not need to be printed on the paper, it would pop open in the form of static electricity and be recycled to the ink tank. Because of the low efficiency of this method, the technology of on-demand ink dripping was developed later, and the ink jet head dripped only when it came to the place where it needed to be printed. Because the ink-jet heads can be replaced, many manufacturers make them in large quantities, which is advantageous in replacement and price, so the ink-jet printing equipment is mainly based on the on-demand ink dripping technology, while the continuous ink-jet heads must be consistently manufactured by the printer manufacturers, so they are not popular. In the field of inkjet printing, inkjet printers mostly appear in the image of color output terminals of personal computers. They do not have high requirements for quality and speed, but they are convenient, maintenance free and cheap

medium and large format inkjet printing technology is mainly used in the fields of digital proofing and inkjet painting. The main manufacturers are Epson, HP, Kodak, Roland, etc. In the field of digital proofing, inkjet printing has the trend of replacing offset proofing and heat transfer proofing with its quality advantages; In the field of digital printing, there are mainly two mainstream systems, electrostatic photography (toner) and inkjet imaging, which are mainly used in special fields such as variable data printing, publications, personality samples, direct mail printing, commercial printing, label printing, trademark printing, and even anti-counterfeiting printing; In the field of large format ink-jet painting, at present, all indoor and outdoor displays, advertisements, posters and other large format printing are mainly made by printing, offset printing and ink-jet imaging. Plate printing is more suitable for making more than 400 single sheet moving parts. However, in terms of the current market, the market demand for single sheet moving parts within 200 is greater. With the increase of multiple varieties and small batch moving parts, the traditional printing methods are greatly limited

among inkjet printing methods, water-based inkjet and paper-based substrate occupy the main market share of large format inkjet, but the proportion of solvent ink and UV curing inkjet is rapidly expanding. From the perspective of environmental protection and substrate adaptability, UV curing inkjet is likely to become the mainstream of large format color market in the future

(2) electrostatic imaging digital printing

electrostatic imaging, also known as electronic photography technology, its basic principle is to form electrostatic latent images on photoconductors by laser scanning, and then realize the visualization of latent images by using the Coulomb force between charged toner and electrostatic latent images, and finally transfer the toner image to the substrate to complete printing

in the digital printing industry, the digital printing technology of still film printing is much more mature than the inkjet technology. At the same time, it is also one of the most widely used and flexible ways in digital equipment. There are two basic modes in the electrostatic photography system. One is the high-resolution system using wet toner development, which generally adopts an 800 dpi imaging system. The main representative product is indigo's digital printing machine; The other is a low resolution system developed with dry toner, which adopts a 600 DPI imaging system, and strengthens the technical cooperation with the 1-wire flexible battery factory, mainly including the products of Xeikon, Xerox, Agfa, Canon, Heidelberg, Manroland, IBM and other companies

generally speaking, the application of electrostatic printing system is relatively flexible, which is basically not limited by the printing volume. It is mainly used in on-demand printing, variable data printing and other markets. It has not only been applied in the fields of commercial Express Printing and office printing, but also in the fields of finance, telecommunications, insurance, publishing and printing, packaging and printing

(3) magnetic recording digital printing

magnetic recording imaging technology adopts the same recording principle as tape recording technology, that is, relying on the directional arrangement of magnetic particles of magnetic materials under the action of external magnetic field to form magnetic latent images, and then using the interaction of magnetic force between magnetic toner and magnetic latent images to complete the visualization of latent images, and finally transferring magnetic toner to the substrate

the magnetic material used in magnetic toner is mainly iron oxide, which has a very deep color. Therefore, this method is generally only suitable for making black-and-white images, and it is not easy to realize color images. Magnetic recording products are mainly used in the printing of securities, lottery tickets, various bills, business forms, labels and magnetic bar codes; Due to the limitations of its product production, this printing method is mainly used in black-and-white images; At the same time, its adjustable step adjustment can only be in a limited range, and its comprehensive quality can only be equivalent to the low-grade level of offset printing. Compared with traditional plate printing, due to the particularity of magnetic recording printing, although its color density is large, it has certain requirements for toner and substrate, so it lacks flexibility

(4) di (direct image) digital printing

di digital printing system is essentially an imaging system that integrates the printing plate of the offset press. The prepared printing plate is used to print a large number of prints with the same content. It is used in the direct plate making printing technology to output the graphic information of the printing plate directly from the computer to the printing plate installed on the printing machine, and complete the plate making and printing at one time. Its printing method is the same as that of traditional offset printing

di printing system (direct stripping fixture) has the characteristics of short preparation time for printing, fast printing (tens of thousands of sheets per hour) and high printing quality. The market is mainly targeted at printing with a printing volume of about 5000. This printing volume of about 5000 copies is too large for other types of digital camshaft handle with three positions of "horizontal", "working" and "lifting", but too small for traditional printing. On the premise of ensuring the printing quality, it can greatly speed up the printing speed, and also has the advantages of offset lithography and digital printing. Its main representatives are heidlberg's quickmaster-di46, workers exposed to solvents need to pay attention to -4, and speedmaster-di, mandroland's Web Di digital printing machine DICOweb. Komori, screen and other companies also have their own Di digital printing machines

although the foreign Di printing system has developed very rapidly, its application in China is not very ideal, and the utilization rate of equipment is generally low. This is mainly because the investment cost of Di equipment is high, and its consumables are expensive. At the same time, due to the difference from electrostatic, inkjet and other equipment, di printer cannot print variable data, so it also needs to charge startup fee

(5) electrocoagulation imaging digital printing

the basic principle of electrocoagulation imaging technology is to condense the ink through the electrochemical reaction between electrodes, so that the ink is fixed on the surface of the imaging drum to form an image area. The oil and ink in the blank area without electrochemical reaction is still in a liquid state, and then scrape the ink in the blank area through the mechanical action of a scraper, so that only the ink in the graphic area is left on the surface of the drum, Finally, the ink fixed on the imaging drum is transferred to the substrate through pressure, so as to complete the whole printing process

electrocoagulation imaging technology can change the pulse width in 15 nanosecond steps, so as to obtain fixed inks with different areas and thicknesses on the imaging roller, and realize multi-step modulation of pixels. This imaging method has no special requirements for the substrate, so the ink can be transferred to the ordinary substrate

the representative of the electrocoagulation digital printer is the product of elcorsy company, with a resolution of 400 DPI. Electrocoagulation imaging system is similar to traditional offset printing, which can be imaged on plain paper; Using pigments, different from the previous digital printing technologies, its adjustable range of step number is wide, which can realize the change range of multiple values, and can basically reach the level of mid-range offset printing

3. The development prospect of digital printing

digital printing is a high-tech printing technology developed in the 1990s. Since the first color digital printing machine was launched by Indigo company in Israel and Xeikon company in Belgium in 1993, more and more large multinational companies have launched digital printing machines, and the digital printing technology has been developed relatively mature. Digital printing has developed rapidly in Europe and the United States in recent years. Germany's manoland company and KBA company, which take the lead in the production field of traditional printing machines, have also actively launched a series of products of digital printing machines. World-renowned large-scale printing machine manufacturing enterprises have entered the field of digital printing, which also reflects that digital printing technology will have broad prospects for development in the future

the development of the printing industry is moving towards short edition and variable data printing, and the printing industry is also launched with the concept of service. Personalized printing is one of this service concept. Digital printing technology, which is different from traditional printing technology, is becoming more and more mature and eye-catching. At the same time, digital printing develops a new concept to develop the market, which is different from the traditional printing business

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