UV UV Curing Technology Creates the Future of Screen Printing

Ultraviolet (UV) curing technology has been widely used, from furniture to optical fiber cables and optical lenses, and it is also expanding new applications.

Screen printing UV ink curing technology has an absolute advantage in the United States and Australia, although its development is not balanced in Europe, but the growth is very fast, UV curing technology will make the screen printing process to the bottom of prosperity.

First, UV screen printing ink quality and output

UV screen printing ink has achieved rapid development in the past 20 years. Due to its high safety and fineness, and the quality and efficiency of UV production technology, it has gradually gained industry recognition. UV inks have excellent ink fastness, which can ensure that the prints of batch prints are uniform in ink color and are not affected by changes in weather conditions. The same products can be printed from Scandinavia to Spain. This is because UV inks do not dry on the web, so for fine contrast prints, or for prints with high light levels, as long as the use of high-mesh screen printing, its quality can fully meet customer requirements. This quality advantage is particularly reflected in water-based UV inks. Because this UV ink does not dry on the Internet and does not block the eyes, it is not necessary to wash the screen plate after printing a plate. This greatly reduces downtime and scrap rates that often occur when solvent-based inks are used, and also significantly increases the wire count. Web printing speed, productivity and economic benefits.

In early 1990, the European advertising printing industry has widely used UV screen printing inks and printed large-format outdoor advertisements using a multi-color screen printing machine equipped with a UV light curing device. The most noteworthy is a multicolor screen printing line with low energy consumption flash or UV curing machine, which is jointly researched and developed by many printer manufacturers such as Sias, M&R, and Svecia, called MCMs. . The emergence of MCMs screen printing production line has played an important role in promoting the development of UV screen printing inks, and changed the direction of development of UV inks. Because when the first flash-type UV light curing machine was put on the market, UV inks suitable for screen printing had not yet been produced. With the advent of new screen printing machines, ink manufacturers must develop inks that are compatible with them, so they have played a significant role in the development of UV screen printing inks. The emergence of MCMs screen printing production lines, together with their supporting low energy UV curing systems and screen printing inks that are later applied to the photo-curing systems, have brought new prosperity to the screen printing industry. At the same time, with the improvement of processing capacity and printing quality, Therefore, it is possible for screen printing to compete with other printing methods and achieve a certain market share. The best example is mass production of large format color outdoor advertising market.

UV curing technology is also continuously expanding its new application areas. For example, in the beginning of 1990, the company successfully developed UV-curable inks for screen printing CDs for the first time, and it also used it with German Kammann filaments. The screen printing machine provided by the network printing machine factory was put into practical production and once again opened up new application fields.

In terms of the quality of color printed images, the use of UV light and solid screen printing systems to screen printing CDs is a leap in production technology compared with pad printing techniques using solvent inks. Images copied to optical discs can almost be Same as color photos. At the same time, due to the flexibility of UV curing technology, it is also continuously applied to a variety of printing areas, such as POP printing materials, printing industry containers and packaging labels. Now, some ink factories in Europe have been able to provide various UV-replacement products for solvent-based printing inks. These products include pre-treated Polyolefin substrates, vinyl substrates for buses and taxi bodies. UV inks, as well as UV plastic inks for a variety of deformable plastics and extruded plastics.

The application of UV curing technology is naturally not limited to screen printing. Manufacturers of UV inks have applied it to a range of other printing methods, such as UV photocurable inks for flatbed digital printers and elastic UV photocurable inks for label printing. However, the number of manufacturers that can supply the above UV light solid ink products to the market is still small.

In addition, UV curing technology can also be used for screen printing. Many MCMs screen printing lines now use larger format screens. Direct exposure printing is not practical and requires a projection system. Since projection emulsions are similar to UV printing inks, the development of UV inks also promotes the progress of screen printing. And this new process is also very conducive to printing small-size POP printing materials.

Second, UV screen printing ink development prospects

How to predict the future of UV inks? What are the benefits of UV curing technology in screen printing in the coming years?

To be sure, the demand for UV inks will continue to grow in the future. One of the world's largest UV ink suppliers, Chrysene Ink Co., Ltd. has only doubled the production of UV inks in the past six years. Its UV ink sales are among the largest among ink suppliers in the world. Still continuing. In terms of market expansion, some printing companies have adopted UV inks and have directly given up traditional production techniques using solvent inks.

For a long time, electronic radiation curing devices (abbreviated as EB) have played a greater role in the drying of ink. The difference between EB and UV curing is that it does not require the use of photoinitiators. The UV photocuring method must rely on photoinitiators to receive the UV light and complete the ink cure by free radical action. The electron beam generated by the EB photocuring device is used instead of UV light to irradiate the ink film of the substrate without the need to complete the curing reaction by radicals. The thicker the ink layer is, the larger the radiation resistance is, and the electron beam penetrates the ink layer deeper than the UV light radiation, allowing the thicker ink layer to cure instantaneously, so the electron beam curing has practical advantages in some fields. This EB curing method has now been applied in some industrial sectors, such as curing drying for decorative coatings for the material industry. However, such equipment must be operated under vacuum conditions, and its bulkiness and high price are not yet practical in the printing industry. However, the prices of EB curing machines have been declining in recent years, and small EB curing machines suitable for the printing industry may appear in the future.

Another trend in UV curing technology may be the use of UV lamps with the trade name Eximer. This kind of special product is different from the mercury lamp, its spectral distribution interval is the highest only 1 ~ 2mμm, so the lamp tube will not produce or only generate a small amount of heat. In theory, this type of Eximer lamp is the ideal replacement for traditional UV lamps. Conventional UV lamps used in existing UV curing machines on the market may cause curling or burning of heat-sensitive materials. However, the use of Eximer light curing process still has two resistances: 1 It requires a dedicated photoinitiator, the cost is higher, and this photoinitiator requires the UV lamp to emit precise UV wavelength to react with it; 2 technology Difficult. It is required to send sufficient energy in such a small ultraviolet wavelength range to complete the rapid photo-solid effect, and there is still a certain degree of technical difficulty.

The positive ion ink curing system will be a replacement product of the current conventional UV light curing machine using free radicals, and will be put into production in the short-term in the screen printing industry. The main feature of this curing technology is that instead of using UV light, ionization reactions are used instead of UV-induced curing reactions. When it enters the ink, positive ion curing occurs with the ink components in the entire ink layer, and it can penetrate the deep layer of the ink until the ink layer and the cross-section layer of the substrate. However, the ionization process of the positive ion curing method is very slow, and it waits until the reaction with all the components of the ink to complete the ion curing. The entire ink curing process takes 24 hours or even longer.

Since UV radiation cannot penetrate the entire ink layer, the effect of the UV curing device is not as good as that of the positive ion curing device for the opaque ink, and the curing speed is slow, which can reduce the occurrence of wrinkles in some special printing products. However, at present, the positive ion curing apparatus is progressing slowly due to its expensive ink composition and the limitations of its use. At the same time, the working efficiency of the positive ion curing device is more seriously affected by the humidity, and some of the initiators contained in the ink are also dangerous to human health and safety. Therefore, the positive ion curing device will not replace the UV curing device now. However, if the price of raw materials falls and the difference in work is obvious, then it may be used in places where special needs are needed. For example, for some very opaque prints, the use of free radical curing can not achieve the purpose of ink curing and drying. With the further application of UV curing technology in special printing fields, such as glass printing or other first-class quality printing, thick ink layer printing and printing requiring no wrinkles, positive ion curing will be understood by more users.

UV water-based inks are recognized as the most promising product in the future. Now, the quality of printed products brought about by the use of UV water-based inks in other printing methods is constantly improving. We can believe that it can provide the best print quality for screen printing.

Another noteworthy aspect is the development of functional inks suitable for a variety of substrates. If it is successfully developed, it will be very beneficial to reduce the burden on the ink storage and transportation department, and thus it can speed up the treatment of ink, reduce the scrap rate, and increase productivity. For advertising printing and industrial screen printing plants, this means that production costs will once again be reduced. In addition, the emergence of new printing materials and changes in user requirements will also affect the direction of UV curing ink. For example, PVC substrates that have remained in use have been replaced by polystyrene in recent years. These conditions will also affect the development of UV inks.

In summary, the role of UV curing technology for screen printing, both now and in the future, is clear and is developing every day. Although UV curing technology is not complicated in theory, to achieve the most perfect state in practical use, it requires the screen printers to correctly understand its basic technology, so that all potential advantages of UV curing technology can be truly played.