On the technical characteristics of seven types of UV inks at home and abroad

In recent years, the development speed of UV ink technology at home and abroad is very fast, mainly reflected in the following points.

1. UV ink for cationic light curing system

The UV ink of cationic light curing system is a research field that people pay attention to at present, because the UV ink of this system has the following advantages.

(1) It is not inhibited by oxygen, which is conducive to a high degree of cross-linking on the surface of the ink, making the coating tough and shiny. The radical photocuring system ink is seriously inhibited by oxygen.

(2) The cationic photocuring system UV ink does not produce unpleasant odor after curing, and once cations are generated after being irradiated with UV light, the curing reaction can continue after the light is stopped, which is conducive to deep curing of thick ink layer and deep ink Curing, which is difficult to achieve with free radical photocuring systems.

(3) After the UV ink of the cationic light curing system is cured, the volume shrinkage is small (generally 3% to 5%), so it is beneficial to improve the adhesion to the substrate. The radical photocuring system ink generally shrinks by 10% in volume after curing, which has a greater impact on the adhesion of the substrate.

Therefore, the use of cationic photocuring system UV ink or free radical / cationic compound photocuring system UV ink can improve the speed of photocuring, especially for the curing of colored UV inks and screen printing UV inks with thick ink film. For the benefit.

It can be seen from the fact that the market growth rate of cationic curing materials is higher than the total growth rate of the UV curing market. UV inks using cationic light curing system or free radical / cationic composite light curing system will be the new development direction of UV inks.

2. Water-based UV ink

In addition to the characteristics of UV inks that have little environmental pollution, water-based UV inks have low viscosity and good rheology, and have a certain relief effect on oxygen inhibition. It solves some technical problems that early solvent-free UV inks cannot be used in gravure and flexographic printing, and is very suitable for gravure and flexographic printing.

3. Mixed ink

Use ordinary ink printing, only after the ink film is completely dried and then UV glazing, can you get a good glazing effect. Therefore, if online glazing is used, the glazing effect is not ideal. If off-line glazing is carried out, in order to prevent the back side of the printed matter from being dirty in the drying stage, powder spraying is required, and the powder spray will make the surface of the originally bright and smooth printed sheet appear sand-like, which affects the appearance of the printed product after glazing.

Mixed ink is a new type of ink prepared by mixing common ink components with UV curing materials. This ink is printed on a traditional sheet-fed printing machine, and after UV lamp irradiation, it can be used for online UV glazing, and UV varnish can be quickly cured on the paper to obtain a uniform high-gloss glazing effect.

Printing with mixed inks has the following characteristics:

(1) Mixed ink printing combines the characteristics of UV light-curable ink and traditional offset ink, so that the ink can show the characteristics of UV ink to the maximum extent after UV light curing. The ink can be cured instantly, greatly reducing energy consumption, reducing production, storage and processing costs, and improving production efficiency.

(2) Special ink roller, blanket and fountain solution are not necessary for mixed ink printing. In this way, mixed ink can be used when online glazing is needed, and ordinary ink can be used when not glazed. As with ordinary ink printing, the effects of different ink rollers, blankets, and mixed inks may be somewhat different.

(3) Printing with mixed ink, its gloss will not fade after UV glazing, especially suitable for printing products with high requirements for ink coverage.

(4) The water-ink balance of mixed inks is relatively easy to control. Because the UV components in the mixed ink will not be cured without being irradiated by the UV lamp, the mixed ink will always flow on the printing machine, and will not cause skin failure on the ink roller like ordinary ink and cause printing failure.

(5) Printing with mixed inks achieves instant drying, so it can be UV-lined on the printing machine without the need of water-based glazing oil. The printing quality is no less than that of ordinary offset printing inks.

(6) Mixed ink can print clear dots and improve printing quality.

(7) At present, most CTP printing plates should not be printed with UV ink, but mixed ink printing can be used.

(8) The investment of mixed ink is low. For printing plants that already have UV technology, they only need to buy mixed inks, while for printing companies that have not yet used UV technology, they only need to invest in UV curing equipment and UV lamps after purchasing mixed inks.

(9) The mixed ink has a wide range of applications. In addition to paper printing, it is also suitable for printing very absorbent printing materials such as plastics, aluminum foil, and metal paper. Solved the problem of ink drying on non-absorbent printing materials.

(10) In addition to the use of sheet-fed printing presses, mixed inks can also be used for narrow-web printing presses.

Mixed inks are now more and more used to print products with high gloss requirements, such as photo albums, pharmaceuticals and cosmetic packaging boxes.

4. New oligomer

Currently, low-viscosity oligomers have been developed and used in UV inks, which can reduce the amount of active diluent that is irritating to the skin in the ink, and if printed on a porous substrate, no monomer adsorption will occur. To the surface. Recently, the United States has developed a new type of flexographic UV ink based on acrylic polyester, which does not contain monomer components, thus eliminating the harm caused by the transfer of monomers to food. The use of low-viscosity oligomers is very conducive to the preparation of low-viscosity UV inks for gravure printing and flexographic printing, especially the inkjet UV inks that are currently developing rapidly.

In addition, with the development of cationic oligomers and water-based oligomers in the field of UV curing, cationic photocuring systems, free radical / cationic composite photocuring systems and water-based UV inks have been developed, improving the performance and application of UV inks range.

5. New active diluent

Many acrylic functional monomers used as reactive diluents affect their application due to their greater toxicity and skin irritation. However, after the alkoxylation, the toxicity of the monomer and the skin irritation are greatly reduced. At present, many alkoxylated acrylic functional monomers have been developed.

Another newly developed active diluent is vinyl ether monomer, which has the advantages of low viscosity, high activity, weak toxicity and low skin irritation. At the same time, such monomers can not only undergo free radical photocuring reactions, but also cationic photocuring reactions, and are very promising reactive diluents. In addition, some cationic reactive diluents suitable for UV ink printing have been developed.

6. New photoinitiator

In order to cure the ink film deep and the colored film layer well, acylphosphine oxide photoinitiators have been developed. It has good absorption of 400nm light waves and high photoinitiation efficiency; the generated free radical absorption moves to short waves and has a "photobleaching" effect, which is conducive to the photocuring reaction deep in the ink film; the final product is colorless, so No yellowing, very suitable for screen printing UV ink with thick ink film. There are also newly developed organometallic photoinitiators of this type.

Since most photoinitiators are small-molecule photoinitiators, they tend to volatilize and migrate during storage, resulting in low photopolymerization efficiency, unpleasant odors, and even toxicity, which affects the use of UV inks in food packaging. At present, some low-odor, non-toxic photoinitiators have been developed. For example, the polymer photoinitiator has excellent performance and can reduce the migration effect. At the same time, the polymer photoinitiator also has the following characteristics: adjust the distance between the photosensitive groups to obtain polymer photoinitiators with different reactivity; use the synergistic effect of the photoactive groups to improve the photosensitive performance; prevent yellowing of the ink layer Change and aging. UV inks using polymer photoinitiators can be used for food packaging printing and have good curing properties.

In addition, with the development of water-based photoinitiators, cationic photoinitiators, composite photoinitiators and hybrid photoinitiators, the performance of UV inks has been further improved and the scope of application has been further expanded. Among them, the composite photoinitiator is a compound of a radical photoinitiator and a cationic photoinitiator, and the curing speed of the UV ink using the composite photoinitiator has been greatly improved; while the hybrid photoinitiator is under UV light, both It can generate free radicals and cations. UV inks with hybrid photoinitiators can overcome the inhibition of oxygen to free radicals and the sensitivity of cationic polymerization to water, and improve the curing degree and physical and chemical properties of ink films.

7. New UV curing light source

(1) The electrodeless mercury lamp can be switched on and off instantaneously, and has a long service life and great efficiency. Unlike the spectrum of medium-pressure mercury lamps, the spectrum of electrodeless mercury lamps used for UV curing is a continuous spectrum that can be used for the curing of thicker ink films.

(2) New light-emitting diode UV curing light source. Light-emitting diodes have many advantages, such as: instant on and off, more than 50,000 hours of lighting life, low operating voltage, low electrical losses, and continuous energy output, which can be said to be very convenient and economical to use. This kind of light source has very little heat, which is very suitable for drying temperature-sensitive prints. Almost all of the light-emitting diodes emit monochromatic light (the half-peak value of the emission wavelength is about 25 μm). For UV curing with special requirements, the emission wavelength can reach 450 nm.

(3) Excimer lamp. The so-called excimer (excited dimer, trimer) is a molecular form that has no stable ground state and only exhibits a weak-bonded excited state. Some important excimers are formed by rare gas, rare gas chloride, halogen, and mercury and halogen mixtures excited by electrons. Several excimer lamp products currently developed are mainly light sources with UV light emission at wavelengths of 172nm, 222nm, 308nm and 351nm. Excimer lamp band distribution is extremely narrow and has high energy, which can quickly cure UV ink. Excimer lamp with a wavelength of 172nm can directly activate acrylate. The energy produced by a xenon chloride excimer lamp at a wavelength of 308 nm can quickly cure UV ink. In addition, the excimer lamp does not generate ozone during the curing of UV ink, and there is no heat transfer to the substrate and production equipment. It is reported that the excimer lamp with a wavelength of 308nm is particularly effective for curing UV inks of the cationic photocuring system.

• PU leather
• 360 degree Spinner wheels that enable mobility over a variety of surfaces especially crowded airports
• Fully lined interior offers two packing compartments with tie-down straps on one side and a zippered divider on the other side to minimize shifting of contents zippered pocket holds delicate items and accessories ;Main compartment expands maximizing space and packing flexibility.
• Ergonomic handle grips allow for maximum control of your suitcase while traveling and moving through crowded airports
• Fully expandable to ensure maximum packing capacity

PU Business Travel Trolley Luggage

PU Business Travel Trolley Luggage,Business Travel Trolley Luggage,PU Business Caster Luggage,Travel Trolley Luggage

Jiangxi Jizhirui Luggage CO.,Ltd. , https://www.jxjzr.com