UV Varnish Common Faults and Solutions

First, the gloss is not good, the brightness is not enough
1. UV varnish viscosity is too low and the coating is too thin.
2. Non-reactive solvents such as ethanol are diluted in excess.
3. UV oil coating is not uniform.
4. Paper is too absorbent.
5. The anilox roller is too thin and the oil supply is insufficient.
Solution: Appropriately increase the viscosity and coating amount of UV varnish according to different conditions of the paper. For osmotic and absorbent paper, a layer of base oil can be used first.
Second, poor drying, light curing is not complete, the surface of the sticky main reasons:
1. UV light intensity is not enough.
2. UV lamp aging, strength weakened.
3. UV Varnish storage time is too long.
4. Excessive diluent added to the reaction.
5. The machine speed is too fast.
Solution: In the case of a curing speed requirement of less than 0.5s, it must be ensured that the power of the high-pressure mercury lamp is generally not less than 120W/cm, the lamp should be updated in time, and do not wait for the bad to change. If necessary, add a certain amount of UV varnish curing accelerator to accelerate drying.
Third, the surface of the printed matter UV light oil is not on the main reasons for hair:
1. The UV varnish has a low viscosity and the coating is too thin.
2. Ink contains excessive varnish or dry oil.
3. The ink surface has crystallized.
4. Ink surface anti-stick material (silicone oil, dusting) and more.
5. The rubberizing roller is too thin.
Solution: When printing products that require UV coating, appropriate measures must be taken to create the conditions. When applying UV varnish, apply thicker coatings. If necessary, use oil on the base or replace special varnish to solve the problem.
Fourth, UV coating coating has white spots and pinholes
1. The coating is too thin.
2. Anilox roller is too thin.
3. Excessive amounts of non-reactive diluents such as ethanol are added.
4. Printed surface dust more.
Solution: The production environment and printed surface should be kept clean and the thickness of the coating should be increased. A small amount of smoothing aid can also be added. The dilution is preferably a reactive diluent that participates in the reaction.
Fifth, uneven surface coating, there are stripes and orange peel phenomenon Main reasons:
1. UV varnish viscosity is too high.
2. The coating roll is too rough to be smooth.
3. Uneven pressure.
4. The coating amount is too large.
5. UV Varnish is poorly leveled.
Solution: Reduce the viscosity of UV varnish and reduce the amount of coating. Even pressure adjustment. The coating roller should be ground and polished. Light leveling agents can be added.
VI, UV light oil adhesion is not good
1. Print ink surface crystallization.
2. Insufficient auxiliary materials in printing inks.
3. The UV varnish itself has insufficient adhesion.
4. Irradiation conditions are not suitable.
Solution: The printing process must be considered in advance glazing conditions. The printed product needs to be coated with an adhesion-enhancing primer.
Seventh, UV light oil thickens, gel phenomenon Main reasons:
1. UV Varnish storage time is too long.
2. Varnish cannot be stored in a dark place.
3. Storage temperature is high.
Solution: Pay attention to the effective period of use of UV Varnish and strictly avoid light storage. The storage temperature is 5°C~25°C.
main reason:
1. Dry curing is not complete.
2. In addition, the light source is insufficient or the lamp tube is aged.
3. UV varnish has poor anti-oxidation capability.
4. UV Varnish Add too much non-reactive diluent.
Solution: UV varnish must be thoroughly dried and cured. And to strengthen ventilation, if necessary, change the UV Varnish varieties.