The pet of packaging and printing: rich application of screen printing technology (below)

5. The digitalization process of screen printing and prepress plates is speeding up
Modern printing technology has entered the digital age, and the continuous maturation of digital printing technology has brought about tremendous changes in screen-making technology. At present, computer-printed plate-making films, photo-taking output films, and inkjet output films are being widely promoted. With the continuous enhancement of the economic strength of the screen printing industry, it is believed that screen printing CTP will become the mainstream of screen printing plate making technology. The computer-to-plate system broke the traditional screen-making mode, completely abandoning the film bottom plate, using the computer screen digital processing technology design required screen printing graphics and text symbols, and in accordance with the screen printing plate requirements for color separation, network management After professional processing and storage in the computer, and then through the digital conversion output, drive a dedicated inkjet equipment, the image will be sprayed onto the screen stencil coated with emulsion, after direct exposure, development (washing) to get the wire Screen printing plates used for screen printing. There is also a method of direct image plate-making, which uses a computer-scanning laser imaging method on a special metal alloy film. This method can eliminate the screen and photosensitive adhesive and does not require a complicated stretching process. No distortion, high level of alignment, and high printing accuracy are the directions for future development.

Sixth, combination printing makes packaging screen printing process colorful
Due to the strong visual impact of packaging, especially some high-end packaging products are seeking unique artistic effects, in order to be unique in the market, so the combination of printing has become one of the popular trends in the packaging field. As we all know, the main advantages of offset printing, gravure printing and flexo printing are the exquisite graphics, rich levels of reproduction, and good dot reproducibility, which are suitable for the printing of fine meshes and fine images. The screen printing is characterized by a thick ink layer, bright colors, high saturation, and a strong three-dimensional impression of printed products, and can achieve a variety of anti-counterfeiting functions and special effects. The appearance of the combination of screen printing and other printing methods has determined that screen printing has an unmissable position in the field of packaging and printing. It has gradually become one of the major printing processes in the field of packaging and printing, greatly improving the quality and grade of products. Product sales also have a certain role in promoting. In actual production, more and more companies have begun to adopt a combination of multiple printing processes to achieve the desired special effects, such as offset printing, screen printing, flexo printing, and screen printing. In particular, the rotary screen printing unit with extremely high printing precision combined with the application of the flexographic printing press makes the printed products icing on the cake. This method can obtain gold, silver and other metal effects and embossing and matte effects on the substrates.

Seventh, screen printing in the field of packaging and printing in the future improvement and development
The printing speed is slower. Although the printing speed of screen printing equipment has been greatly improved at present, it is still relatively slow compared to other printing processes. If the production volume is too large, it may restrict production and affect delivery time.

Long ink drying time. The thick ink screen printing feature brings great difficulties to drying and takes a long time; printed products cannot be piled up immediately, and many drying racks and large work places are required.

Accuracy and stability need to be further improved. From the point of view of production control and quality, the accuracy and quality stability of screen printing are inferior to those of offset printing and gravure printing. In particular, the accuracy of domestic screen printing machines still has certain problems, which may easily result in inconsistent product quality during production. Not only between batch products, but even the same batch of products is difficult to ensure the consistency of hue, specifications, etc.

higher cost. At present, the cost of screen printing is still relatively high. This mainly includes two factors: First, the ink thickness of screen printing is relatively large, and the use of ink is relatively large, which of course increases the cost; second, the production efficiency of screen printing is relatively Say it is lower, the same process effect, screen printing will take more time, this will also increase the cost of production.

Multi-color overprinting is more difficult. The current screen printing equipment is basically monochrome printing. If you want to achieve a variety of effects on the same product or perform multi-color overprinting, there will often be inaccurate color registration and cause a lot of waste products, not only a waste of time and resources, but also affect The delivery date is even the next order.

The market needs multicolor automatic screen printers. In order to increase production efficiency and overprint accuracy, it is hoped that fully automatic screen printers will be able to develop in the direction of multicolorization, and will be popularized and popularized, so that domestic packaging and printing users can fully enjoy the advantages brought by multicolor automatic technologies.

Ink should develop toward environmental protection. In general, China's production of screen printing ink is relatively complete, and some of the quality is very good, it should be said that rapid development. The problem is that the proportion of solvent-based ink solvents accounts for 60%. When drying, the solvents must be evaporated in the air, so the pollution is serious. With the rising popularity of environmental protection, the government has also successively introduced a series of related policies to formulate relevant standards. The environmental protection requirements of customers for packaging products will be higher and higher. Therefore, the development of environmental protection inks will be increased in the future.

Screen printing materials need to increase development efforts. China's screen printing industry is currently in a relatively backward state from equipment to materials, from platemaking process to printing and post-press processing, and has not formed scale and modernization. In particular, the use of high-quality, high-precision inks and special-purpose inks, four-color screening inks and UV inks are almost entirely imported. Therefore, the screen printing industry must actively absorb modern science and technology so that the screen printing technology can be rejuvenated and create greater economic value.

Digital printing will replace some of the screen printing market. Printing, computer graphics and other non-printing technologies will play a major role in the small print market, and will certainly replace some of the traditional application areas of screen printing. This has also shaken the determination of some screen printing companies to screen printing in the end.

Digitization of screen printing is the future direction of development. The introduction of direct plate-making technology by screen printing companies will face problems such as changing the entire workflow, installing new equipment, and training personnel. Moreover, due to the immature digital workflow in China's silk screen industry, the investment recovery cycle is longer. These factors will become an important reason to hinder the digitalization of China's screen printing plates.

As we all know, in the packaging and printing industry, screen printing plays a very important role in improving package quality, enhancing sales promotion effect, and enhancing value-added products. It is believed that with the improvement of equipment and materials and the improvement of process technology, screen printing will be The packaging field will surely achieve greater breakthroughs and development.

Author/Zhong Zehui

Source: Packaging Printing and Processing 2005/12