Flexographic printing has been developed in the domestic market for over 10 years and has achieved remarkable results in many application fields. The current quality characteristics of the flexographic printing market are: large patterns, large color blocks, with text and lines as the main focus, medium to coarse dots (with a screen size of less than 133 lines/inch), and the best color gamut is the middle tone (circular screen images with a screen area of over 2% to 3% and less than 70% have the strongest hierarchical expression). This article focuses on several publicly available flexographic latest technologies and their characteristics.
Several Latest Flexographic Printing Technologies
Firstly, the flat top dot technology of laser flexography. This is a hot technology in recent years, which further improves the wear resistance of high gloss small dots on the basis of direct plate making technology, thereby improving the printing plate's resistance rate.
Secondly, Kodak FlexcelNX flexographic printing dot technology. It uses square laser technology to randomly generate multilateral rectangles, and the minimum dot diameter of the printing plate reaches 10 μ M.
Thirdly, Esco HD network technology. Using a circular laser, during the main exposure process, due to the involvement of oxygen, the photosensitive resin reaction is not thorough. By washing the plate, the dot becomes sharper and the diameter becomes smaller.
Fourth, Japan Asahi Kasei's washing technology. Its characteristic is that it has a printing plate surface tension that matches the surface tension of UV ink, so it is not easy to cause plate blockage in printing. I have conducted tracking tests on this type of printing plate and found that its surface tension is 1-2mN/m lower than the surface tension of the laser printing plate we usually use.
Fifth, DuPont's thermal version technology. This is an environmentally friendly technology that is truly worth our attention. It uses heating to turn the uncured photosensitive resin from a solid to a liquid, and then uses non-woven fabric to suck out the liquefied resin under a certain pressure. It eliminates the interference of plate washing solution (including organic and water-based solvents) on the surface tension of the printing plate, and can control the surface tension of the inking and concave areas of the printing plate without fluctuation.
Sixth, ContiTech's rubber plate technology. It is built on the foundation of offset printed rubber cloth, and the resistance rate of offset printed rubber cloth is very high, which can reach 5-6 million prints. Therefore, reducing the cost of flexographic printing is a worthwhile approach to consider.
Seventh, other prepress technologies for flexographic printing, such as square and circular mesh technology, mixed mesh technology for special areas, and micro hole technology on the printing plate surface (on-site screening technology).
What are the characteristics of the new flexographic technology?
Firstly, flat top dots are a significant correction to laser flexography, restoring and improving the UV curing strength of the printing plate and increasing its printing resistance.
Secondly, the most fundamental principle of flexographic printing determines the characteristics of the printing plate. The flexographic ink printing process has the highest printing plate resistance, which can exceed the printing resistance of the gravure plate of 600000-700000 (without stripping, after one electroengraving). However, the printing plate resistance of the flexographic UV ink and solvent ink printing process is much lower, and the printing plate often encounters a large number of problems during the second printing, such as independent point breakage, printing plate cracking, wear and tear Insufficient printing resistance, lack of mesh, etc.
Thirdly, there are shortcomings in traditional plate washing methods, namely the fluctuation of the solubility of the plate washing solvent. In fact, flexo suppliers have fixed testing methods for washing solvents, such as regularly testing a few data points and then adding specific solvents according to the test values. But how many companies in the industry insist on doing so? To the best of my knowledge, everyone has used up their old solvent and replaced it with a new one. As for what is missing and what is needed, only a few companies are doing so. Because of this, it causes fluctuations in the surface tension of the printing plate.
Fourthly, the study of printing plate surface tension that matches the ink surface tension is worth paying attention to, and in recent years, many domestic enterprises have been carrying out work in this area. To my knowledge, a company that specializes in packaging KFC products has found in production that after determining a certain type of printing plate, if different surface tension inks are used, the probability of the printing plate not blocking greatly increases. So, new technologies based on the basic principles of flexographic printing are worthy of our strong attention, and frontline flexographic printing technicians in China have keenly observed this.
In short, quality and cost are the internal driving forces of flexographic printing innovation. Whether it's flat top dots or fine small dots, they are all aimed at improving the quality of flexographic printing and reducing its costs. It's not a purely theoretical issue, but a practical cost and practical issue.