The challenge of UV inks to printing plates

(Solid flexo printing with UV inks-a chalenge for printing plates)

Nowadays, the quality of flexible printing is getting higher and higher, and the proportion of UV inks is increasing. From the paper box to the self-adhesive labels, it is inseparable from its participation. Compared with other inks, UV inks can be adjusted by the amount of ink, printing on the media more colorful, more compact works in the field.

However, it also has a drawback, that is, the monomer molecules of the UV ink and the molecular structure of the monomer on the photographic printing plate are similar in nature and can easily cause molecular diffusion, thereby causing deformation of the printing plate, commonly known as printing plate expansion. Plate makers 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 hybrids or inks incorporating cationic surfactants, has contributed to the unremitting efforts of the plate-making companies to improve their products and make better use of this UV ink. BASFPrinting System is such a company.

We conducted comparative experiments on various types of UV inks in the market related to the expansion deformation and the printing effect. The results showed that various conclusions about the performance of printing plates can only play a role in guiding reality. Therefore, most of the statistics listed in this article are only experimental results and are for reference only. After the experiment, this article also gave a brief look at the new version of the nyloflex series.

Printing Tests The plates used in this experiment were nyloflex FAH, digiflex FAH DII, and some flexographic printing plates commonly found on the market. Ink is used by BASF and other companies. The experimental conditions are the same and the time is six hours. Ink roller 320 lines/cm (800 lines/inch), 60 degree screen line, ink supply 3 cubic centimeters per square meter.

After 3 hours of uninterrupted operation, we found that the ink fountain temperature has increased from the original 20°C (68°F) to the current 40°C (104°F). It can be concluded that there is a certain correspondence between the printing time, the printing temperature and the reproduction of the dots, and the temperature may also have a certain influence on the printing plate expansion. The experiment also found that the hardness change of the plate is only about 1 degree, which is far from 6 degrees in the static expansion experiment, and the change of hardness is not every time. From this it can be concluded that the change in the hardness of the printing plate during the printing process only has a minimal effect on the printing quality.

It is the focus of this experiment to observe the change of dot reproduction caused by the deformation of the printing plate. The phenomenon of printing plate expansion caused by the reaction between the printing plate and the UV ink is mainly manifested in the following two aspects:

With the prolongation of the printing time, the printing plate will be thickened due to the influence of the ink and the printing plate reaction, which will press the nip between the printing cylinder and the printing plate, so that the material between the parts shrinks and deforms, resulting in the printing plate base. Larger print dots make the dots more variegated.

At the same time, because the halftone area is filled, the print quality is greatly reduced. If the print pressure is greater, then this printing will cause considerable damage to the printing plate, greatly reducing the service life of the printing plate.

Plates and Test Results This experiment was conducted on two types of plates, traditional and digital plates. In all traditional printing plates, FAH printing plates perform best and the performance is very stable. Especially under the conditions of various UV inks, they all have good performance. Once again, they prove that the FAH printing plate is the king in the flexographic printing plate. status. Other types of printing plates are rarely exposed, and there may be fluctuations in tone performance.

Nyloflex FAH plates burst out of flash in high-quality halftone flexible printing. In particular, thin-printing processes with flexible linings are used to print flexible packaging films and printed products such as packaging papers, labels, cartons, shopping bags, and aluminum foils.

In digital printing plates, FAH DII and another printing plate exhibited characteristics that were higher than those of conventional photographic printing plates. In particular, the maintenance of outlets is no longer expanding, reflecting the quality of digital printing plates. Digital plate-making by laser etching and oxygen ambient exposure imaging can effectively reduce the image volume and plate thickness.

Especially for the delicate dots of high-light parts, digital platemaking can transform it into intermediate or solid shades that can be printed in the printing, instead of washing the colors like the traditional printing plate.

Under proper printing pressure, the digital printing plate can reflect all the delicate parts of the original product in the printed product without any omission, thus maintaining the sharpness of the printed product. The experimental results show that for extremely delicate parts, and in the case of long-term use of UV inks, the digiflex FAH DII plate shows only a little bit of color drift. This proves that it is the best choice when printing with UV ink.

Nyloflex sprint plates This type of plate, 1.14 mm (or 0.045 in) thick, is a new product designed specifically for use with UV inks. It has appeared at Drupa but was not found in this experiment. It is a washable plate that can be processed in 30 minutes. When UV inks are used for a long period of time, there is no noticeable swelling change in such plates. With a Shore hardness of 77 to 79 degrees, it is an ideal high-quality UV half-tone flexographic printing tool. In addition, it also comes with an inexpensive waste water processor that can directly convert printing waste water into biodegradable water that can be discharged, demonstrating its other advantages.

The high performance of this type of printing plate is also reflected in the reproduction ability of fine highlights and fine-tuning areas. The screen cable can reach 60 lines/cm (150 lpi). It has anti-UV ink, good ink transmission performance, small dot gain, and printing. High quality features.

Summary This experiment tested the swelling performance of all printing plates under UV ink and found that the nyloflex FAH printing plate and the digiflex FAH DII printing plate are two kinds of UV inks with better usability in the BASF Printing Systems printing system. The nyloflex sprint product is an extension of this UV-applicable principle. It provides a strong backing for UV ink manufacturers to continue to develop new products and raises the UV ink printing product to a new level.