Coating technology of the hottest UV UV coating

UV coating technology

add UV coating on ordinary ink. 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 materials, but the flexible packaging enterprises must keep up with the pace of market recovery, 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 priming paint, especially. 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. For this reason, it is recommended to use two coating units and extended drying section for high-quality coated prints

ultraviolet (UV) coating

now, offset printing and clearing machines and table surfaces are mostly brushed with 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 UV paint (rubbing UV with each other at a regular speed), 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

ul859:42 only the coating without foam can produce good gloss 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