Ultraviolet Ink Technology from Theory to Practical Extension (3)

American perspective

When Europe developed water-based inks, the U.S. market did not stop developing UV inks. In the United States, the invention of UV inks suitable for printing on vinyl and polyethylene webs is critical. These substrates have their own unique problems during the printing process. For example, adding plasticizers to vinyl can improve ink handling and durability. The successful development of UV technology together with the raw material developers has created a unique and lasting solution for this substrate. Other substrates, such as polyolefins, also bring about some special problems with adhesion and durability. However, UV inks solve these problems well.

The United States also hopes to provide solutions for more industrial markets, such as printing on dials, dashboards or fast cars. The inks used in these fields must have strong durability and abrasion resistance, and they must be very flexible.

The main advantages of this kind of technology development, especially for global companies, are that ideas and technologies can be generated at the same time and implemented simultaneously. This brings about a leap in the development and application of ink technology.

What will happen in the future? How will UV technology promote the development of screen printing in the coming years? One thing is certain: that is, people's demand for UV technology will continue to develop. In the markets of developing countries, such as Eastern Europe, the new printing business is flocking to the ultraviolet technology, and out of the traditional, solvent-based technology circles. Looking into the future of UV technology, it also has some potential, and some of them can also be used in screen printing.

Electron beam (EB) curing systems will also play a long-term role. The biggest advantage of the EB curing system is that it does not require photolithography. It promotes the cross-linking reaction by emitting electrons to the ink layer, instead of emitting ultraviolet light, and does not require radicals. The action of photolithography absorbs ultraviolet light, releases free radicals, and promotes cross-link curing. The EB system also contributes to the formation of a thicker ink film because the penetration of electrons in the ink layer is more thorough than that of ultraviolet light.

Thicker ink layers can bring higher opacity, which is useful for some applications. The EB system has been used in a number of areas, such as wood coating; however, such equipment can only be used in a vacuum environment, and it is still relatively large and expensive for the screen printing industry today. In spite of this, the prices of EB devices have dropped further in recent years, and in the future there will be smaller devices that can be used in ordinary printing environments.

Another possibility is the use of Eximer UV lamps. Unlike mercury vapor lamps, the spectral distribution of this particular product is very narrow, at most 1 or 2 nanometers, so the amount of heat it produces is negligible. In theory, it is very suitable for heat-sensitive substrates, when the traditional UV curing system, these materials are prone to shrinkage, curl or ignition and so on. However, Eximer still faces two problems. The first is to prepare a photolithographic plate that can accurately respond to the wavelength of light emitted by the Eximer lamp. The second is to create enough energy to achieve high-speed curing in such a narrow UV wavelength range.

Anion ink systems can now also replace traditional, free radical ultraviolet light curing technology, and can bring more short-term opportunities for screen printers. The biggest feature of this system is that it does not require UV light to penetrate the entire ink layer (through the ink/substrate interface), but when the UV light reaches the ink, it can promote cross-link curing of the components in the ink layer. The occurrence of the reaction - this reaction will continue until all the ink components have been consumed. It takes about 24 hours or even longer if the ink is completely dry.

Because it does not require energy to enter the entire ink layer, the negative ion system can be used for more opaque inks, and its slower drying speed also helps to avoid the problem of substrate shrinkage and increase printing adhesion. The slow development of negative ion systems is mainly due to the relatively expensive and relatively rare ink components required. The performance of the anion system is also related to the operator, and the photolithography used in the ink may also cause health and safety problems.

Anion systems may never replace the current UV curing technology. However, if the cost of raw materials is reduced and their popularity is improved, then anionic inks can be widely used in printing with higher opacity. With the deepening of UV technology in the product area, negative ion systems will become more popular - for example, printing on glass or other materials, can achieve superior adhesion, the desired ink thickness and lower Contractility.

Multiple substrates products may also be a focus. With the application of UV ink systems on a variety of substrates, the inventory of ink will be reduced, which makes the color distribution system more widespread. This will help speed up the processing of ink, reduce waste, and increase the efficiency of the printing plant.

In the same way, the emergence of new substrates and changes in customer preferences will also influence the future direction of UV inks. For example, the industry has strict restrictions on the use of PVC. Such products have become unpopular in recent years. Therefore, people are increasingly demanding new drums, such as polystyrene, which can change the direction of UV inks.

Final evaluation

The development speed of UV inks is shocking. It has been the preferred technology in many fields since it started 25 years ago. Today's UV inks can be printed and decorated on virtually all surfaces without the surface, and UV coating can also be affected by temperature and stretching. The issues of health and safety, as well as the issues of stability and durability that were previously raised, have now become distant memories of people.
Source: Bison