Most popular in ordinary ink plus UV coating

2022-09-19
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Add ultraviolet (UV) coating on ordinary ink (bottom)

priming material

Add UV coating on ordinary ink in a coordinated way. The usual practice is to use diffusion coating for priming first. Ordinary offset ink and ultraviolet (UV) coating are incompatible chemicals, and this "intermediate coating" needs to be applied to the printing sheet in a wet superimposed form in a short time. The water-based diffusion synthesis solution contains about 40 to 45% solids, and its flow resistance (viscosity) varying with temperature can be adjusted by adding water

Once the diffusion coating is applied to the printing sheet, a considerable amount of water must be sucked into the printing material, and some will disappear due to volatilization. It is only at this time that the polymer begins to bind and form a tight coating film. In the process of linkage processing, the priming material must be able to dry as soon as possible

the drying speed, flexibility, penetration ability, traction ability, flow resistance (viscosity), gloss and adhesion that can be achieved depend on the base material and the additives used

the function of priming paint as a bonding and balancing element

from the increase of the type and quantity of priming paint used, its important function is clearly shown

especially on the surface with high ink coverage, there is a change in weight and mixing, which affects the primer more significantly. Figures 4 and 5 illustrate these relationships

turn the 13 cubic centimeter roller per square meter into 18 cubic centimeter roller, and the ultraviolet (UV) coating layer is smoother and glossier (photos 3 and 4). This situation is more obvious in places with high coverage

different types of primer. Its influence is also easy to identify: comparing Photo 5 (left) and photo 6 (right), the primer on the left is relatively hard and has good gloss; The primer on the right contains a soft color developing agent. Applying hard and glossy primer on the surface with 400% ink coverage can increase 35 gloss points; Even on the surface with 100% ink coverage, the difference of more than 15 gloss points can be measured (Figure 6)

when using soft primer, serious paper deformation can only be seen on the surface of 200% of the field. The hard primer appears to have a smooth surface before UV coating. However, the ability to resist rubbing flowers is weakened. The type of priming paint has a strong influence when relatively few components are used

these tests clearly show that drying between coating units is extremely important. If the drying time and drying condition are not enough before applying UV coating, the best primer and the most effective amount cannot achieve the best gloss. It is for this reason that it is recommended to use two coating units and extended drying department to predict high-quality coated prints for the 2019 paper industry

ultraviolet (UV) coating

nowadays, offset printing mostly uses chemical root solid coating. These ultraviolet (UV) coatings contain color developing agents, chemical reaction diluents, and photoinitiators. Under the irradiation of UV light, it plays a formative role and makes the coating become solid (solidified). UV light causes the photoinitiator to release chemical radicals, which leads to the polymerization of acrylate; That is to form a long chain. Oxygen interferes with this reaction

for cationic solid coatings, UV light initiates ions; It's cascading to create a solid situation. Because of the continuity of curing, although it takes a long time, it will be completely solid. Although the reaction process is inhibited by moisture, cationic ultraviolet (UV) coating method is mostly used in food packaging because it has no smell and is completely solid. Our tests focus on chemical roots of solid ultraviolet (UV) coatings

UV coating layer and gloss that can be achieved

increasing the amount of UV coating can improve the gloss (photos 9 and 10), but the effect is not as good as increasing the amount of primer. When testing, increase the amount of ultraviolet (UV) paint from 20 to 30 cubic centimeters per square meter, and increase the gloss by 10 points regardless of the ink layer coverage. When determining the amount of ultraviolet (UV) paint, don't forget that depending on its flow resistance (viscosity), too much is difficult to apply smoothly (photos 7 and 8)

heating ultraviolet (UV) paint to 40 ℃ can enhance fluidity and increase gloss at the same time

the geometry of the textured roller also affects the smoothness of the coating. In addition to the load capacity, its line condition also plays a role

only the coating without foam, and then create a good light input data * re-use effect. When the pit of the roller is full of paint, small bubbles form in the paint, causing micro foam. This situation can be improved by adding defoamer and properly combining the paint circulation system to ensure that the paint will not be stirred too much

drying is necessary

in a few seconds, the material giving color and gloss is applied to the substrate. Although manufacturers try their best to make these films change from liquid to solid quickly, high-speed printing is limited. Therefore, the process must choose the appropriate drying support

drying is determined by the production speed

high speed production is certainly desirable, but remember that the described drying method has limited power of the dryer. When the production speed increases, it is difficult to completely dry and firm the printing surface to maintain an acceptable heat. After printing, this situation directly causes the printed sheets to be on the receiving pile ldquo; In neonatal care, the interaction between paper surface and paper bottom. If the influence causes visible conditions, it is called anti India. Ultraviolet (UV) coating products will not stabilize until several days later. Gloss and bonding quality can still change after 24 hours, depending on the ink and glazing paint used. However, change is not necessarily a disadvantage. Please refer to figure 7

the coating surface after the beam is solid should be maintained in its condition. After drying, don't let the bottom of it change. The printed sheets are stacked one by one in the paper receiving department, which is under considerable pressure. Therefore, the printing surface should be solid to ensure that it will not be damaged by contacting the bottom of the first printed sheet. This solid surface is caused by the appropriate beam energy generated by the UV dryer

drying causes the temperature of the receiving stack to rise, causing reverse printing, and even making the paper stick into blocks. Therefore, the most important thing for the combination of printing machines is to apply appropriate drying energy at an appropriate time. Therefore, after the printing and coating machine, it really needs the support of infrared (IR) lamp plus cold air or warm air and air extraction. To dry water-based diffusion coatings, it is recommended to use two extended drying parts in the form of transfer between two coaters. If you think that only the drying time determines the gloss effect, then add a transmission part between the two coaters to ensure that the production speed can be increased by 40% without affecting the gloss. Figure 8 shows that the output energy of the dryer must match the production speed. The output energy of UV should follow the random speed, but not the linear mode. IR output energy is linear mode

production: the faster the better

when the speed of the printer increases, the gloss decreases depending on the ink coverage. As mentioned above, the interval between the application of individual paint layers determines the stability of the formed "base course". The paper moves at the speed of 10000 sheets per hour between the units, and the ink can only penetrate into the paper in less than a second. These tests let the ink penetrate at normal production speed. Comparing the gloss of the first and last printing ink, the result shows that the gloss of the last printing ink is poor. This situation can be used for reference to arrange the printing layout and color sequence. However, while the gloss can be increased, the speed of the printing machine increases, but the gloss decreases due to the use of ordinary ink. The inherent problem of this ink is a fact that cannot be concealed. However, the selection and coordination of ink, coating and adjustment of dryer can minimize such quality degradation

summary

the effect that ultraviolet (UV) paint can achieve depends mainly on the substrate. Apply high gloss diffusion coating on a certain kind of substrate, and adhere to air circulation when applying ultraviolet (UV); Don't tamper with the parts of each unit to provide a good pointer to the expected effect of the paint on the substrate. Ink, especially in the case of high coverage, can cause the gloss to weaken, but it can be improved with dense pigments and inks that are easy to penetrate. The composition of the ink and the affinity of its backing material determine the degree of adhesion of the coating layer to them, and the adhesion is stable after a few days of printing. Proper selection of the type and weight of priming materials plays a decisive role in the gloss that can be achieved. Ultraviolet (UV) paint is the surface layer, which helps prevent scratching. At the same time, if it is evenly coated, it will become a bright surface. Choosing an appropriate combination of machines, especially in the drying section, and coordinating the condensation of materials and inks, the printing press provides a number of prerequisites for achieving the best results

the requirements for product quality are constantly improving, prompting the corresponding improvement in the selection of appropriate materials, the appropriate combination of printing machines and the skills of machine operators

the process we studied is a special application. The information provided by relevant partners helps printing companies achieve results. This study shows that the cooperation between users and manufacturers of printing presses, coatings, inks, substrates and so on is extremely important. No company can do it alone, but can make full use of the maximum benefits provided by this method. (Manroland)

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