For example, silk screens can accumulate thick layers of ink, which are distinguished by their excellent hiding power. They are mainly printed on substrates with opaque white, like "no-look" signs. Silkscreen color is suitable for printing thick, thick patterns and text. On the other hand, the printing speed of screen printing is the slowest one compared to the other printing processes. Both offset printing and embossing have good graphic sharpness and high printing speed, but their acquisition cost is high and they lack sufficient hiding power compared with screen printing. Flexographic printing power is worse than silk screen printing, but higher than offset printing and embossing. Flexographic printing speed and print resolution are stronger than silk screen printing, but they are slightly inferior to offset printing and embossing. Look, it happens to be between low-end screen printing and high-end embossing and offset printing. Each of these processes has its own inherent limitations when used individually. If they are selected for their optimal characteristics and combined with each other to form a narrow web production line, they can be obtained for the user at the best output efficiency. The best image clarity offers a variety of options.
The number of signs printed using the combined printing process is rapidly increasing. There are two fundamental reasons for this. First, the end-users are always looking for ways to make their products more competitive on the shelves of supermarkets, and the difference is precisely the first in this consumable and brand-name product area. demand. The concept of innovation on packaging and decorating has promoted continuous technological innovation. Driven by this innovative concept, the market is optimistic about the combined printing process, especially the flexographic and screen printing processes using UV-curing inks. Second, due to the improvement of the performance of printing presses, inks, printing materials, and other auxiliary materials, the combined printing process has been rapidly promoted and trusted. As a result, the post-press processing of high-end label products has also been promoted into various medium and small-scale enterprises in the printing industry. It is no longer confined to processing in a few large printing plants, thus opening up wider applications.
Second, the advantages of UV-curing inks Now, the development of inks, especially UV-curing ink technology has become one of the main factors to promote the development of printing process technology. It promotes the market's growing demand for combination printing processes. UV curing inks have made significant progress since entering the market 20 years ago and have played a leading role in the silk screen industry. In some cases, they have become an ink curing process that people are willing to use. So far, the quality and stability of UV-curable inks have reached a very high level and are easy to use, so the application in other printing processes has also achieved significant growth. In fact, 8 of the 10 new presses currently added to the flexo industry are equipped with at least one UV curing press. Compared with other ink curing methods, the advantages of UV-curable inks are not only in the processing process, but also in the print quality level, which can achieve effects that cannot be achieved by other processes. From the processing point of view, the advantage is that the curing process of the UV ink is very stable, and the entire process needs only to be completed from under the UV lamp. This process allows printing, hot stamping, die-cutting and any other post-printing process to be carried out on a single machine for continuous production, so that maximum productivity can be achieved with minimal effort during processing. In addition, the good adhesion properties of UV inks are suitable for a wide range of substrates, including plastic films such as BOPP, PET, polyethylene, polystyrene, and co-extruded composite films that were difficult to handle in the past. Due to the excellent adhesive properties of UV inks, the pre-press assistive working time is significantly reduced.
UV inks do not contain volatile components, such as solvents or water, that do not change color and printing characteristics. In the printing, UV inks are easy to maintain the stability of color and viscosity. Once the ink is adjusted before printing, the adjustment workload on the printing machine is very small, and it is unnecessary to add other additives. When printing is stopped midway, the ink on the light roll and the anilox roll will not dry. The surface of the UV ink layer has extremely high abrasion resistance and chemical stability, which is also the main reason why the label product adopts combination printing. UV inks have a high hiding power and gloss, and the clarity of prints is also high, which fully reflects the end user's demand for product quality - enabling the user's products to achieve outstanding results in the market.
Third, the challenge of combination printing Clearly, this combination of quality and ease of use once the successful printing process, anyone will follow, the market will also be filled with a large number of similar products. Although this process has become very reliable, in fact, there are still some difficulties in mastering. For print operators, there are still a series of controversial issues, and there are quite a few variables that need to be effectively controlled, such as:
1. When purchasing a combination printer, the printer must ensure that the sequence between the printing units is sufficiently variable to accommodate the combination of printing processes required for various prints. In general, the hot stamping unit is always placed at the end of the printing unit. When the screen is used to print the color version, the screen printing unit is placed before or after the flexo printing unit or even in the middle. When it comes to printer configuration, consider whether each unit should be a fixed or variable decision.
2. The composition of the inks used in different printing processes is different. Different inks are not always compatible with each other because different technologies are supported by different chemical principles. This creates problems with overprinting and adhesion between inks used in two different systems. For example, non-silicon UV flexo inks often cause poor overprint performance on silicon-containing screen printing inks; inconsistencies between inks produced by different manufacturers often occur, even at the same manufacturing plant. Incompatibility issues can also occur between product lines. When such incompatibility is encountered, it is usually solved by the operator adjusting the ink on the printing machine. However, the best method is to test the ink compatibility before printing and obtain technical support from the ink supplier.
3. Ink is sometimes incompatible with other finishing processes such as: hot stamping, ink jet, and laser-printing graphics. Proper testing or technical support from the ink supplier is to overcome this. The key to failure.
4. When the same color is used for ink color matching with different printing processes, because the manufacturers often choose pigments from different substrates for preparation, this means that when using different process inks, such as screen printing ink and flexo printing ink, color matching will often occur. There is a problem. For those who have not undergone regular color matching training or lack of advanced color matching spectrophotometers, the error in color distribution is considerable.
5. The speed of printing on a combination printer is always tied to one of the slowest speeds, such as a hot stamping unit or a rotary screen printing unit. For example, a flexo press using UV ink can reach speeds of up to 300 feet per minute. If the speed of the press is only 100 feet per minute, when the prints need to be stamped, they cannot run at 300 feet per minute. .
6. It is important for the factory to train operators on various printing processes because different processes require different types of operating skills. Many aspects of skill training are necessary measures to ensure that operators have a variety of process operations and fully understand the technical parameters of various processes.
7. When the printing plant first stepped into the combined printing process, another training target was the factory's sales staff, not only to enable them to deal with the customer's supply department, but also to ask the designers and customers to create design staff. Communicate and interact closely with each other in the design process of the final product