UV screen printing matte ink printing common problems and solutions
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In recent years, screen printing has become more and more widely used in the high-end packaging printing market. The special effects of screen printing such as freezing point, snowflake, light change, convex word and matte make the packaging products more beautiful. However, there are some common problems in the application process. Below, the author takes Jiangsu “Jinsha Yipinmei” cigarette pack as an example to analyze the common problems and solutions in the printing process of UV screen printing matte ink.
“Nanjing (Jinsha Yipinmei)” cigarette pack has a high sand content due to its high ink content, resulting in high ink solid content, high ink viscosity, lack of fluidity, and easy to appear in the printing process. some problems. Common problems and solutions are now shared here.
Surface shrinkage
1. Principle of formation
The initial state of the ink transferred from the printing plate to the substrate is a uniformly distributed ink dot which is not completely extended and joined together before entering the drying system, so the ink layer on the surface of the printed matter does not completely cover the surface of the printing substrate, thereby Produced a small gap like a pinhole.
2. The main reason
(1) The ink has poor fluidity.
(2) The ink is likely to generate bubbles during the printing process, and the bubble surface is broken to cause uneven distribution of the ink surface.
3. Solution
(1) Try to remove the solid filler other than the sand powder in the ink component to improve its fluidity.
(2) Adding UV diluent to make the ink thinner and increase fluidity.
(3) Add an appropriate amount of antifoaming agent and leveling agent to improve the printing effect.
Dry edge phenomenon
1. Principle of formation
If the ink layer of the printed matter is thick, there will be a significant "step" phenomenon in the printed area and the blank area. In the case of consistent blade pressure, the actual pressure of the ink will be larger in the printing area than in the blank area, while the UV screen printing sanding ink has a strong matte feel, the sand powder content is relatively high, and the particles are relatively large, so during the printing process, The edge position at the transition of the printed area to the blank area is prone to dry edges.
2. The main reason
(1) The sand powder particles are large, the mesh number is high, and the mesh is small.
(2) The blade printing pressure is insufficient.
(3) The viscosity of the ink is insufficient, and the components are easily dispersed after being subjected to a certain pressure.
3. Solution
(1) Select a medium ink with a moderate amount of sand particles and a screen with a moderate mesh size to match the two.
(2) Adjust the blade pressure.
(3) Adding a resin component which increases viscosity to the ink enhances the integrity of the ink composition.
The ink is shallow and deep before the sand, and the sand is weak before the strong phenomenon
1. Principle of formation
Screen printing This unique printing method determines that small particle size components such as monomers, resins, and auxiliaries in the ink component are easily transferred to the substrate at the time of printing than large particle size components such as pigments and sand powder. This makes the ink composition on the screen inconsistent in the printing cycle from the time of ink refilling to the next ink refilling, and the sand sensation changes from weak to strong and the ink color changes from shallow to deep.
2. The main reason
(1) The ink has a high solid content, and the composition is not easily formed into a whole body, and the separation between the components is fast.
(2) The printing characteristics of screen printing are determined.
3. Solution
(1) Adding a resin liquid which increases encapsulation to the ink, as far as possible, the components of the ink are integrally formed and uniformly transferred to the substrate.
(2) Add automatic ink refilling and ink returning system to the equipment to minimize the cycle time.
Paste phenomenon
1. Principle of formation
During the transfer of the ink onto the substrate until it is completely dry in the drying system, due to its poor fluidity, the printed small text will be slightly smaller than the actual size of the printing plate, resulting in unclear text.
2. The main reason
The fluidity of the ink itself is unstable.
3. Solution
(1) In the case where the viscosity of the ink is determined, the actual size of the printing plate is enlarged according to the actual printing condition.
(2) Thickening the ink in the case where the actual size of the printing plate is determined.
In addition to the above common problems, screen printing UV matte inks will also have other quality problems in the printing process, which requires the operator to learn and use the conditions and process, and analyze the reasons reasonably. Find solutions and summarize them in a timely manner, and continuously accumulate experience to improve their technical level.