Analysis of the usage of the hottest UV ink in maj

Analysis of the use of UV ink in major printing processes

offset printing

offset printing can be divided into sheet fed offset printing and web rotary offset printing according to the state of the substrate. Sheet fed offset printing is suitable for paper, paperboard, plastic sheet and metal foil printing; Rotary offset printing is fast, suitable for large quantities of books, newspapers, business forms and self-adhesive printing. When using UV ink in offset printing, the following aspects are mainly considered: ink curing of non absorbent substrate; Ink emulsification may hinder the adhesion of ink and substrate; The speed of rotary printing machine is fast, which requires the curing speed of ink to match the printing speed, especially for self-adhesive printing and Securities printing with special ink. The printing effect of UV ink is better than that of resin offset printing ink

offset printing is mostly used for fine product printing. UV curing can reduce the loss of small dots and improve the ink transfer rate of chromatic overprint. When selecting ink raw materials, we should comprehensively consider the influence of each component on UV ink. In terms of experimental grounding wire layout, we should also pay attention to the following protective measures: to ensure the best printing effect. As the offset ink film is generally 2 ~ 3 m, although it is conducive to light curing, the ink film is thin, and the hiding power of pigments on the printing surface will be affected to a certain extent, so it is generally necessary to increase the pigment content in the formula; With the increase of pigment content, the light transmittance of the ink film will be reduced, which is not conducive to UV curing; And the ink film itself is thin. If the wettability of the pigment is not good, the pigment and filler are easy to be exposed to the surface of the ink film, affecting the gloss of the ink film. Therefore, it is necessary to choose pigments with good dispersion. When using UV offset printing, you should also pay attention to the following points

(1) different inks should be selected for substrates with different properties, and the light transmittance, curing rate, covering property of the ink and the gloss of the print surface should be comprehensively considered

(2) in color printing, the ability of various pigments to absorb UV photons is different, and their transmittance from high to low is m, y, C, BK, so the curing degree of various colors of inks is also different. The transmittance directly affects the excitation energy of photons to photoinitiators, so it is appropriate to arrange the printing color sequence as BK, C, y, m, so that the ink with poor light transmittance can absorb photons as much as possible and enhance its curing effect

(3) the use of alcohol fountain system can reduce the surface tension of the ink and promote the curing effect. In the printing process, the fountain solution can be used to strengthen the oil drainage area (blank part) of the printing plate, so as to ensure that the lipophilic area is fully ink friendly and the hydrophilic area is not inked

improving the ink formula and adding corresponding additives can increase the hydrophobicity of the ink, but too strong hydrophobicity will lead to the shrinkage of the ink at the edge of the image, the loss of fine layers, unclear point boundaries, etc., which will affect the quality of the print

(4) UV printing requires high surface strength of paper, and it is easy to cause galling failure if the surface strength is not enough. When printing with gold and silver cardboard, because the surface of this kind of paper is smooth and the affinity for ink is small, the ink of the first color is easy to be pulled out when overprinting with the second color. Therefore, in UV printing, the paper with large surface tension should be selected, the color sequence should be reasonably arranged, and the relevant process parameters in the printing process should be adjusted to avoid and reduce the occurrence of the above phenomena

flexographic printing

flexographic printing is a printing process that has developed rapidly in recent years. The graphic part of the printing plate is higher than the non graphic part, and it is flexible, which can better express the subtle level and outline of the graphic part. In addition, it is suitable for a wide range of substrate materials. In addition to traditional paper, some non absorbent substrate materials, such as plastic film, aluminum foil composite paper, cellophane, etc., can also be used for flexographic printing

when using UV ink for flexographic printing, in addition to the problems of coloring, curing and adhesion, we must also pay attention to the influence of ink components on ink viscosity and rheology, so as to obtain better printability and stability

the flexographic printing process determines that the UV ink used should not have high viscosity. There are two kinds of traditional flexographic printing inks: solvent based and water-based. A large amount of solvent or water is needed to adjust the viscosity. Due to the use of a large amount of solvent, most flexographic printing inks are similar to Newtonian fluid in rheology, which will lead to ink sedimentation and instability. Therefore, giving flexographic printing inks appropriate thixotropy can prevent pigment flocculation and sedimentation

flexographic printing ink uses active diluents to reduce the viscosity of the system, so its viscosity may be higher than that of solvent based flexographic printing ink on the whole. Although the viscosity of UV flexographic printing ink is lower than that of printing and offset printing ink, the addition of pigments will improve the viscosity, especially when the wetting, dispersion and stability of pigments are not handled well. In addition, the consideration of price factors is based on the consistency of all aspects of quality configuration requirements. The influence of pigments on ink rheology is more important, and appropriate thixotropy is beneficial, because when the molecular cross-linking inside the ink reaches a certain degree and pseudoplasticity occurs, the viscosity of the ink system without pigment dispersion stabilizer will drop sharply on the high-speed ink roller, However, when leaving the ink roller and entering the printing part with relatively low speed, the viscosity will rise rapidly, and the wetting effect on the surface of the substrate is too poor, which is not suitable for printing. 2. Safety device brush of electronic tensile testing machine. The ink containing appropriate dispersion stabilizer has certain stability, and its viscosity is not high. After high shear, the viscosity rebound is relatively slow, and the printing adaptability is good

printing

the solid content of silk printing ink is 100%, and there is no component volatilization. The thickness of ink film after curing is basically unchanged, which is conducive to obtaining a higher film thickness. The printing and curing process is easy to control, which can avoid blocking, spots and other failures, and reduce downtime

although UV printing has many advantages, the determination of light initiation conditions affects the curing quality of the inking layer. If it is not selected properly, it only solidifies faster on the surface of the ink film. On the other hand, UV is printed with its advantages. This kind of packaging structure is also convenient for food to be heated in the microwave oven, that is, although the ink film is thick, low pigment content can achieve high hiding power, which is a favorable condition for the curing of the bottom layer. On the premise of not hindering the saturation and hiding power of the pigment, properly adding transparent fillers with good refraction, increasing the concentration of transparent medium in the ink layer, also helps to improve the light absorption of the underlying initiator. Because the printing ink film is thick, the printing accuracy is not very high, and the particle size of the pigment can be larger. Therefore, without sacrificing the dispersion of the pigment, the particle size of the pigment can be appropriately increased to increase the actual transmittance of the ink, so as to facilitate the solidification of the bottom layer