Introduction of HD flexographic technology and its impact on packaging and printing

In China's domestic packaging market, offset printing and gravure printing dominate, and flexo printing accounts for a very low percentage. Although flexo printing has been on the rise in recent years, it is only a small increase. Flexo printing has always been developing and innovating in recent years. Since the flexographic platemaking technology was introduced into the market in 1995, the precision and quality of plate-making in packaging printing have been improved. At the same time, some defects in the traditional plate-making technology have been avoided and the flexographic plate-making technology has achieved a qualitative leap. However, since the advent of direct platemaking technology, some inherent defects in flexo printing have not been well resolved. For this reason, high-definition flexo printing technology came into being and became the promoter of flexo printing development. Bisheng Xiaobian will focus on high-definition flexo printing technology and briefly describe its impact on the future development of the packaging printing market.

Learn about HD flexo technology

HD flexo technology consists of high-resolution laser imaging technology and high-definition dot technology:

1. High-resolution laser imaging technology

Flexo plate direct imaging technology usually has an imaging resolution of 2100ppi, a laser spot size of 18μm, and high definition flexographic technology has an imaging resolution of up to 4000ppi, and the laser spot size is reduced to 6μm, which not only can reproduce the image details better, but also It can avoid the occurrence of moiré, and more importantly, the image resolution of 4000ppi has more usable grayscales. In addition to meeting the 256-level gray level usually required in the design stage, it can be retained after the compensation of tone. Sufficient gray levels provide the print with excellent visual quality while also providing high definition and high contrast.

2. HD network technology

HD network technology uses a brand new screening technology in the high-light area, which is different from the “hybrid” screening in the usual sense, but “differential modulation” screening. In other words, the dots maintain the regular grid arrangement, just like the standard AM circular dot, but in the highlight area, there is no independent dot or irregular gap dots by changing the dot size. In the end, these differentiated outlets will also participate in printing, so that the high-light areas can achieve a gradient-to-zero printing effect, and at the same time ensure the printing plate's durability.

At the same time, high-definition network technology selectively uses special screening technologies for the field and shadow areas, namely, micro-cell technology. The general sense of the micro-cell structure applied to the entire printing plate will affect the overall quality of the printed image, and the high-definition dot technology allows the solid and dark tone areas to reach the gravure printing effect through controlled micro-cells. Among them, controllable means that the micro-cells do not appear on the edge of the pixel, so that the edge of the printed graphic or dot can be kept intact and sharp. In addition, under the printing conditions using the same amount of ink, micro-cell technology can be used to obtain a smoother, higher density of the field, as well as a higher contrast tone.

The 3 parts of the core of HD dot flexo technology:

In the printing design in Europe and the United States, the emphasis is generally placed on the use of linework and text, while our country is accustomed to the use of exquisite pictures, especially character images. Although the emergence of digital flexography has greatly improved the quality of flexo printing, it is still difficult for the gradual change from the field to the end of the network, and “hard mouth” often appears.

(1) Using a high-resolution output device combined with digital flexo platemaking, the output resolution of the platesetter is as high as 4000 dpi, which has exceeded the limitations of previous output devices. With the same dot area rate, output devices with high resolution can get smoother dots on the edges, which is also helpful for fine-grained and detailed reproduction of printed products. At the same time, high-resolution output devices can also implement high-overline network cables. The number of plate-making, of course, this also takes into account printing machine anilox roller and ink to high network printing with the issue. It is worth mentioning that with the high-resolution plate-making machine, the printing capacity of small texts can also be greatly improved. With a 4000-dpi direct plate-making mechanism version, a positive and negative 1pt (0.35146mm) can be printed clearly and completely. word.

(2) The use of frequency modulation and amplitude modulation hybrid screening technology, combined with the concept of network reinforcement, makes it possible to print 175 lpi and 0.4% dot. For example, in a label printing company in the south, after adopting high-definition dot flexographic technology, its printed products can stably get 0.5% to 1% of the outlets. Under the same conditions, the traditional flexo platemaking technology can only obtain 4% outlets. As the dominant concept of high-definition dot flexography, the idea of ​​dot strengthening is worth exploring. In flexo printing, isolated dots are usually least resistant to printing, but if more dots are added around isolated dots, the overall print resistance of the media can be increased. To give a simple example, in the open plains, a lonely tree is difficult to withstand storms. If trees are planted together, each tree in the forest can protect each other and it is much safer. In flexo printing, isolated dots can be seen as independent “big trees,” and the impact from the anilox roll and the substrate is similar to the impact of wind and rain on the trees.

In the high-definition screen flexo technology, the high-light area outlets are generated using large outlets. The smaller outlets surround the surrounding area, and the smaller outlets have a slightly lower height, which provides support for large outlets, and large outlets can More impact from the anilox roller and substrate, thereby protecting the small dots from heavy pressure.

(3) Accurately control the plate making process to ensure that the quality of the manufactured plates is stable. It is not difficult to see from the above description that for the production of high-precision dot-matrix printing plates, controlling the size of large outlets and surrounding small sites to enable stable printing is an important part of the technology, so precise control of the plate-making process All parameters, the strict inspection of the quality of the finished plate is a necessary part of this technology.

The above characteristics of the HD dot flexographic technology require upgrading of the prepress system in most cases. In the environment tested by the author, it was found that most printing devices can print high quality flexo prints without upgrading, so the technology Once launched, it was welcomed in the European market. At the label exhibition in Brussels, Belgium, in September 2009, there were many proofs using high-definition dot flexographic technology. In China, some label printing companies have succeeded in converting some offset and gravure printing products to flexo printing, which has reduced the cost and quality of printed products. The author sincerely hopes that with the help of high-definition dot flexographic technology, China's flexo printing technology can achieve considerable development and progress.