Some common faults and solutions for UV varnish
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
First, the gloss is not good, the brightness is not enough
main reason:
1. The viscosity of the UV varnish is too small and the coating is too thin.
2. Excessive dilution of non-reactive solvents such as ethanol.
3. UV oil coating is uneven.
4. The 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 the different conditions of the paper. For paper with high osmotic absorption, a layer of base oil can be applied first.
Second, dry is not good, light curing is not thorough, the surface is sticky
main reason:
1. The UV light is not strong enough.
2. The UV lamp is aging and the strength is weakened.
3. UV varnish storage time is too long.
4. Add too much diluent that does not participate in the reaction.
5. The machine is too fast.
Solution: When the curing speed requirement is less than 0.5s, it must be ensured that the power of the high-pressure mercury lamp is generally not less than 120w/cm, and the lamp should be updated in time, so don't wait for it to be replaced. If necessary, add a certain amount of UV varnish curing accelerator to accelerate drying.
Third, the surface of the printed matter UV varnish can not be painted, hair
main reason:
1. UV varnish has a small viscosity and the coating is too thin.
2. The ink contains too much varnish or dry oil.
3. The ink surface has been crystallized.
4. There are many anti-adhesive materials (silicone oil and dusting) on the ink surface.
5. The glue roller is too thin.
Solution: When printing products that require UV glazing, it is necessary to take corresponding measures to create conditions. When applying UV varnish, apply a proper thickness. If necessary, solve the problem by applying oil or replacing special varnish.
Fourth, the UV coating has white spots and pinholes
main reason:
1. The coating is too thin.
2. The anilox roller is too thin.
3. Add too much non-reactive diluent (such as ethanol).
4. The surface of the printed matter is dusty and so on.
Solution: The production environment and the surface of the printed matter should be kept clean and the coating thickness increased. A small amount of smoothing aid can also be added. It is preferred to use a reactive diluent that participates in the reaction.
Fifth, uneven surface coating, streaks and orange peel
main reason:
1. UV varnish viscosity is too high.
2. The coating roller is too thick and not smooth.
3. The pressure is not uniform.
4. The coating amount is too large.
5. The leveling property of UV varnish is poor.
Solution: Reduce the viscosity of UV varnish and reduce the amount of coating. The pressure is adjusted evenly. The coating roller should be ground and polished. A light leveling agent can be added.
Six, UN varnish adhesion is not good
main reason:
1. The surface of the printed ink is crystallized.
2. The auxiliary material in the printing ink is not suitable.
3. UV varnish itself has insufficient adhesion.
4. Light curing conditions are not suitable.
Solution: The printing process should consider the glazing conditions in advance. Printed products need to be coated with a primer that enhances adhesion.
Seven, UV varnish thickens and gels
main reason:
1. UV varnish storage time is too long.
2. The varnish is not completely protected from light.
3. The storage temperature is too high.
Solution: Pay attention to the effective use period of UV varnish and strictly avoid light storage. The storage temperature is preferably from 5 ° C to 25 ° C.
Eight, the residual smell is large
main reason:
1. Dry curing is not complete.
2. Insufficient UV source or lamp aging.
3. UV varnish has poor resistance to oxygen interference.
4. The non-reactive diluent in the UV varnish is added too much.
Solution: UV varnish must be dried and cured thoroughly. And to strengthen ventilation, if necessary, replace the variety of UV varnish.