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Common problems of UV varnish

Information Sources:Internet posted on:2020-06-17

Common problems of UV varnish: 1. Poor gloss and insufficient brightness 1. The viscosity of UV oil is too small, the coating is too thin 2. Excessive dilution of non-reactive solvents such as ethanol 3. Uneven coating 4. The paper is too absorbent 5. The anilox roller is too fine and the oil supply is insufficient. Solution: According to the different conditions of the paper, increase the viscosity and coating amount of the UV varnish appropriately: you can apply a layer of primer to the paper with strong absorption. Second, the drying is not good, curing, the surface is sticky 1. The intensity of ultraviolet light is not enough 2. The UV lamp is aging, the light intensity is weakened 3. The UV varnish storage time is too long 4. Too much diluent that does not participate in the reaction is added 5. The solution of the machine speed is too fast: in the case of curing speed less than 0.5s, generally should ensure that the power of the high-pressure mercury lamp is not less than 120W/cm; the lamp tube should be replaced in time, if necessary, add a certain amount of UV varnish to promote curing Agent to accelerate drying. 3. The UV varnish on the surface of the printed matter can not be applied, and the flower is the main reason 1. The viscosity of UV varnish is too small, the coating is too thin 2. The content of ink or dry oil in the ink is too high 3. The ink surface has crystallized 4. Too much anti-sticking material (silicone oil, powder spraying) on ​​the surface of the ink 5. The line of the anilox roller coated with glue is too thin 6. Problems of construction technology (technical personnel are not good at technology) Solution: For products that require UV coating, corresponding measures should be taken when printing to create certain conditions: UV varnish can be applied thicker, if necessary. Base oil or special varnish formula. 4. The UV coating has white spots and 1. Coating and thin 2. The anilox roller is too thin 3. Excessive addition of non-reactive diluent (such as ethanol) 4. There are many dusts on the surface of the printed matter. Solutions: Keep the production environment and the surface of the printed matter clean; increase the thickness of the coating; add a small amount of smoothing aid: call the release agent a good active diluent. 5. Uneven coating of UV varnish, streaks and orange peels 1. The viscosity of UV varnish is too high 2. The anilox roller wire is too thick (the coating amount is too large), the surface is not smooth 3. Uneven coating pressure 4. Poor leveling of UV varnish Solution: Reduce the viscosity of varnish and reduce the amount of coating; adjust the pressure evenly; the coating roller should be finely polished; add a bright leveling agent. 6. The adhesion of UV varnish is not good 1. Crystallization of printed matter ink surface 2. The additives in the printing ink are not suitable 3. The UV varnish itself has insufficient adhesion 4. Inappropriate photo-curing conditions Solution: The printing process should consider the glazing conditions in advance; apply primers to enhance adhesion on the printed products. 7. The UV varnish becomes thick and has a gel phenomenon. Main reasons: 1. The UV varnish storage time is too long 2. UV varnish failed to be completely protected from light 3. The storage temperature of UV varnish is too high. Solution: Pay attention to the effective use period of UV varnish and store it strictly in the dark. The storage temperature is preferably 5~25℃. 8. Large residual odor Main reason: 1. UV varnish curing 2. Insufficient ultraviolet light or UV lamp aging 3. Poor anti-oxygen interference ability of UV varnish 4. Excessive addition of non-reactive diluent in UV varnish. Solution: UV varnish is cured, and ventilation should be strengthened, if necessary, replace varnish varieties.
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