Nowadays, the quality of flexible printing is getting higher and higher, and the proportion of UV ink is becoming larger and larger. From the carton to the sticker, it is inseparable from its participation. Compared with other inks, UV ink can adjust the amount of ink to print more colorful and solid works on the media.
But it also has a disadvantage, that is, the monomer molecules of UV ink are similar in structure to the monomer molecules on the photosensitive printing plate, and it is easy to cause molecular diffusion, resulting in deformation of the printing plate, commonly known as printing plate expansion. Plate manufacturers can use special plate-making methods to control this deformation within a certain range, extend the life of the plate, and improve the printing effect. The continuous introduction of new UV inks, such as new hybrid or cationic surfactant-added inks, etc., has prompted plate-making companies to make unremitting efforts to improve their products and make better use of this UV ink. BASF Printing System is one such company.
We conducted comparative experiments on various types of UV inks on the market in terms of expansion and deformation and printing effects. It was found that various conclusions about the performance of the printing plate can only play a guiding role in reality. Therefore, most of the statistical data listed in this article is only an experimental result, which is for reference only. After the experiment, this article also made a simple outlook for the new printing plates of the nyloflex series.
Printing test
The printing plates used in this experiment are nyloflex FAH, digiflex FAH DII and some common flexible printing plates on the market. The ink uses products from BASF and other companies. The experimental conditions are the same, and the time is six hours. Ink supply roller 320 lines / cm (800 lines / inch), 60-degree screen line, ink supply is 3 cubic centimeters per square meter.
After 3 hours of uninterrupted operation, we found that the temperature of the ink fountain has increased, from the original 20 ℃ (68? H) to the current 40 ℃ (104? H). It can be concluded that there is a certain correspondence between printing time, printing temperature and dot reproduction, and the temperature may also have a certain effect on the expansion of the printing plate. The experiment also found that the hardness change of the printing plate is only about 1 Shore, which is far from 6 degrees in the static expansion experiment, and this hardness change is not every time. It can be concluded that, in the printing process, the change of the printing plate hardness has only a minimal effect on the printing quality.
Dot reproduction
Observing the changes of the dot reproduction caused by the deformation of the printing plate is the focus of this experiment. The phenomenon of printing plate expansion caused by the reaction of printing plate and UV ink is mainly manifested in the following two aspects:
As the printing time is extended, the printing plate will be thickened due to the reaction between the ink and the printing plate, which will press the impression line between the printing cylinder and the printing plate, causing the material between this part to shrink and deform, resulting in the printing film base The dots become larger, making the dots have extra noise.
At the same time, because the halftone area is filled, the printing quality will be greatly reduced. If the printing pressure is higher, this printing will cause considerable damage to the printing plate, greatly reducing the service life of the printing plate.
Plate and test results
This experiment is based on two types of printing plates-traditional printing plates and digital printing plates. Among all the traditional printing plates, the FAH printing plate performs the best and the performance is very stable, especially under various UV ink conditions, it has a good performance, and once again proves that the FAH printing plate is the king in the flexographic printing plate. status. Other types of printing plates rarely show outstanding performance, and there will be ups and downs in the tone performance.
The Nyloflex FAH printing plate bursts with many flash points in high-quality halftone flexible printing. Especially when the flexible plate liner is used to print flexible packaging film and packaging paper, labels, cartons, shopping bags, aluminum thin and other printed products.
In the digital printing plate, FAH DII and another printing plate show higher characteristics than the traditional photosensitive printing plate. Especially in terms of keeping the network from expanding, the quality of the digital printing plate is reflected. Digital platemaking can effectively reduce the imaging volume and the thickness of the printing plate through laser etching and oxygen environment exposure imaging.
Especially for the delicate dots in the highlight part, digital plate making can convert it into intermediate or solid tones that can be printed in printing, instead of washing out the colors like traditional printing plates.
Under the appropriate printing pressure, the digital printing plate can reflect the various delicate parts of the original product in the printed product without omission, so the freshness of the printed product is maintained. The experimental results show that the digiflex FAH DII printing plate only shows a little color drift for extremely delicate parts and when using UV ink for a long time. This proves that it is the best choice when printing with UV ink.
nyloflex sprint plate
This kind of printing plate with a thickness of 1.14 mm (or 0.045 inch) is a new product specially designed for the use of UV ink. It has appeared at the Drupa exhibition, but it was not found in this experiment. It is a washable printing plate that can be processed in 30 minutes. When using UV ink for a long time, there is no obvious change in the expansion of this printing plate. Its Shore hardness is 77 ~ 79 degrees, making it an ideal high-quality UV halftone flexographic printing tool. In addition, it is also equipped with a low-cost waste water processor, which can directly convert printing waste water into biodegradable water that can be discharged, and shows another advantage of it.
The high performance of this printing plate is also manifested in the good highlight and fine adjustment area dot reproducibility. The screen screen line can reach 60 lines / cm (150lpi), with UV resistant ink, good ink transfer performance, small dot expansion, printing High-quality features.
to sum up
In this experiment, the expansion performance of all printing plates under UV ink was tested, and it was found that in the BASF Printing Systems printing system, nyloflex FAH printing plate and digiflex FAH DII printing plate are two products with good practicality of UV ink. The nyloflex sprint product is an extension of this UV application principle. It provides a strong backing for UV ink manufacturers to continue to develop new products and raise UV ink printing products to a new level.
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