Application of the hottest UV luminous ink in scre

2022-08-24
  • Detail

The application of UV light-emitting ink in printing

preface

China is very rich in rare earth resources. There are many varieties of rare earth light-emitting materials, and they are also widely used. Rare earth luminescent materials can be combined with inks to actively promote the production of photoluminescence safety signs through plate printing. According to the different requirements of the place of use, the environment and customers, PVC rigid low foaming PVC plates or flame-retardant ABS materials can be used to make fire signs. At present, the development of photoluminescence safety signs in China has broad prospects, and its social and economic benefits are immeasurable. In the past, thermosetting luminous ink was mostly used to make luminous safety signs, which has the disadvantages of large solvent volatilization, complex process, time-consuming, large energy consumption and so on. Therefore, the development of an ink with simple process, clean and environmental protection, and energy saving has become the focus of attention

u V ink uses ultraviolet light as energy. After being irradiated by ultraviolet light, the photoinitiator in the ink produces free radicals or cations to initiate polymer curing. In the UV curing system, there is no need to add volatile solvents. The prepolymer and diluent in the raw materials have polymerization activity, and all of them are cross-linked to form a film during curing. Therefore, there is no solvent evaporation, which is known as "a new green industrial technology facing the 21st century"

combining UV curing ink with rare earth luminescent materials to prepare UV luminescent ink can make the printing process clean and environmental protection, low energy consumption, suitable for continuous production, and UV curing products have excellent performance, which is incomparable with other curing methods in gloss, wear resistance, hardness, solvent resistance, beauty and other aspects. UV luminescent ink is a new type of ink suitable for modern industrial production

application of luminous ink in plate printing

adding luminous powder to ink is a general method to prepare luminous ink. In the past, thermosetting ink and luminous powder were mixed to prepare luminous ink. With the development of UV technology, the combination of luminous powder and UV ink to prepare UV luminous ink has been gradually adopted by the majority of printing manufacturers, especially in the production of luminous signs, using UV luminous ink instead of thermosetting luminous ink has considerable advantages. Using plate printing technology to print UV luminous ink is a common method to prepare luminous signs

1.1 choice of luminous powder

u V luminous ink should consider the choice of luminous powder in plate printing. The basic requirements of luminous powder are high brightness and moderate particle size. Large particle size cannot be omitted from the plate, small particle size, insufficient printing thickness, need to increase printing times to meet the thickness requirements, waste time, use 50 ~ 80 μ M phosphor is suitable. Rare earth luminescent powder is light yellow and green, so the substrate for making signs should be blue or green

1.2 version making

luminous signs generally require that the luminous layer be printed thick, so the version of 80 mesh polyester monofilament is usually used, so that the luminous powder can pass through the version, and the printed luminous layer is also relatively thick. In plate making, it should be considered that in general label products, such as some place name labels, the same pattern will not be printed continuously for many times. In this case, low-grade oil-resistant and sexy light glue can be selected, which can save costs

1.3 pre coated bottom layer

a white bottom layer needs to be printed before printing the light-emitting layer, and the light-emitting layer is printed on the white bottom layer. The bottom layer is one of the necessary steps for printing luminous ink. Precoating the bottom layer on the surface of the substrate will help to improve the luminous performance of the coating. The experimental results show that the primers with different pigments have different effects on the luminescent properties of the coating. 1. The effect of amorphous materials is different. The white primer with titanium dioxide is the most conducive to improve the luminescent properties of the coating, because the white coating can make the incident light and emitted fluorescence through the coating more fully reflect, and maximize the role of the fluorescent coating

it should be noted here that u v luminous ink needs to have good adhesion on the white bottom layer, otherwise the luminous layer is easy to fall off after curing. Generally, ordinary p V C ink is selected, because most U V inks have good adhesion on P V C, so the phenomenon of the luminous layer falling off the label can be avoided

1.4 curing method

at present, The production process of thermosetting ink is to print the first color (usually dark color first) → send the high-efficiency infrared or far infrared dryer (conveyor belt dryer) for surface drying → print the second color (color sequence usually from deep to light) → send the high-efficiency infrared or far infrared dryer for surface drying → print the nth color → send the high-efficiency infrared or far infrared dryer for surface drying for N times → finally fill the bottom color and flatten it (finishing color) → high efficiency infrared or far infrared dryer surface drying → send infrared or far infrared drying oven for complete curing and drying. It can be seen from this that the curing process is cumbersome and consumes a lot of energy. However, the UV ink can be cured immediately after being printed directly through the UV curing machine. The cured product can immediately proceed to the next procedure. The process is simple and saves time greatly

1.5 other problems

when using UV luminous ink, we should pay attention to a very important problem. There is a obvious deformation and then fracture before reaching the maximum load Pb. In the production of signs, it is often necessary for the luminous layer to reach a certain thickness. At this time, it needs to be printed many times to meet the thickness requirements. Because the UV ink is cured immediately after printing once, and the cured surface is smooth, it is carried out on the basis of the previous layer for the next printing. At this time, the UV ink needs to have good adhesion between each layer, and there can be no delamination. Therefore, special attention should be paid to the problem of interlayer adhesion in the selection of UV ink

comparison between luminous ink and traditional thermosetting luminous ink

the composition of UV ink is very different from that of traditional ink. The film formation of UV ink is a chemical action, and the monomer and polymer polymerize under the action of initiator, while the film formation of traditional ink is a physical action. The resin is already a polymer, and the solvent dissolves the solid polymer into a liquid polymer, which is printed on the substrate, and then the solvent is volatilized or absorbed, Make the liquid polymer return to the original solid state

2.1 composition and advantages of UV luminous ink

u V ink structure includes resins, monomers instead of solvents, additives and photoinitiators. The resin in UV ink is very different from that in solvent volatile ink. It is reactive and can react with a product in other chemical reactions. In UV ink, it can react with monomers. Monomer is a kind of chemical substance with low molecular weight, which can replace solvent to some extent and reduce viscosity, so it is suitable for printing. But in addition to acting as a solvent or diluent, it also plays a very important role - participating in chemical reactions. Each component of UV ink can react chemically, because it is 100% cured, and all components will become solid through chemical reaction

2.2 advantages of UV ink in printability

u V ink has a great improvement in printability and printing quality compared with solvent ink. Because UV ink is 100% solid and has no volatile solvent, the viscosity of the ink will not change with the change of environmental conditions. In the past, printers had to complete a long cycle of printing, especially when printing fine patterns, they always encountered the problem of viscosity change. When scraping ink before and after printing, the solvent volatilization changed the viscosity, and the thickness of the ink layer would be different every other period of time. The viscosity of U V ink will not change after working for one day, and the quality of printing products is exactly the same. In terms of cleaning, UV ink will be put into the curing equipment for curing immediately after printing, so the printed matter does not contact many impurities, which can keep the product clean. Solvent based inks need to be dried for a long time after printing. When there is a lot of dust in the environment, it will pollute the products. When making luminous signs, they often need to be printed thick and need to be printed many times to meet the thickness requirements. At this time, traditional ink is used for printing. After each printing, they have to walk in the drying channel once, which requires a lot of time and energy. When using UV curing ink for printing, it does not need to be dried in the drying channel. It can be cured immediately after each printing, and the next process is carried out, which greatly saves time and energy

in general, UV ink has the following advantages: 1) it does not contain volatile organic solvents, has little pollution, does not damage human health, has a solid content of 100%, and does not have the problem of inconsistent thickness of printing ink film due to the volatilization of solvents; 2) The ink is not blocked, which is conducive to the printing of fine products; 3) In printing, do not worry about the damage of solvent to the substrate, the ink quality is stable, the gloss of dry ink film is good, and the ink film has good wear resistance, water resistance, oil resistance and solvent resistance; 4) Instantaneous drying of ink can organize a rapid printing production line and greatly improve the printing efficiency; 5) Save ink during printing. Solvent based ink can print about 50 m2 per kilogram, while UV ink can print 70 M2 under the same circumstances

conclusion

UV radiation curing technology is a new green technology developed internationally since the 1970s. The UV curing ink produced by this technology, referred to as UV ink, has the advantages of no volatile organic compounds (VOC), less environmental pollution, fast solidification speed, energy saving, good performance of cured products, suitable for high-speed automatic production, etc. The traditional ink is volatile and slow to cure, which is not conducive to environmental protection. Therefore, UV ink can be said to be the main substitute of traditional ink. At present, UV ink has become a more mature ink technology, and its application scope is expanding day by day. With the progress of UV ink production technology and the development of UV ink raw materials, UV curing technology will make greater progress in the future. UV curing luminous ink, as a kind of UV ink, will also have greater application in plate printing

reprinted from: silk printing

Copyright © 2011 JIN SHI