Common Quality Problems And Countermeasures Of UV Coating On Paper Products

Date:Jan 11, 2018

1-bad gloss, brightness is not enough


main reason:

1, UV Varnish viscosity is too small, too thin coating.

2, ethanol and other non-reactive solvent dilution.

3, UV coating uneven.

4, the paper is too absorbent.

5, Anilox too thin, insufficient fuel supply.

The solution: According to the different conditions of the paper to increase the viscosity and coating amount of UV varnish. On the permeability of paper, can be coated with a layer of base oil.


2- poor drying, light curing is not complete, the surface sticky


main reason:

1, UV intensity is not enough.

2, UV lamp aging, strength weakened.

3, UV varnish storage time is too long.

4, do not participate in the reaction diluent added too much.

5, the machine speed is too fast.

Solution: In the case of curing speed requirements of less than 0.5s, must ensure that the power of high-pressure mercury lamp is generally not less than 120w / cm, the lamp should be updated in time, do not wait for a bad change. If necessary, add a certain amount of UV Varnish curing accelerator, accelerated drying.


3- printed surface UV varnish coated, hair flowers


main reason:

1, UV Varnish viscosity is small, the coating is too thin.

2, ink containing varnish or dry oil too much.

3, the ink surface has been crystallized.

4, ink surface anti-sticking material (silicone oil, dusting) and more.

5, coating roller too thin.

The solution: When printing on the products that require UV coating, corresponding measures must be taken to create the conditions for thickening the UV varnish. If necessary, the problem can be solved by replacing the varnish with the special varnish.


4- UV coating with white spots and pinholes


main reason:

1, the coating is too thin.

2, anilox roller too thin.

3, non-reactive diluent (such as ethanol) added too much.

4, printed surface dust and more.

The solution: the production environment and printed surface should be kept clean, increase the thickness of the coating. Can also add a small amount of smooth additives. Dilution is best used to participate in the reaction of reactive diluent.


5-uneven coating surface, there are stripes and orange peel phenomenon


main reason:

1, UV Varnish viscosity is too high.

2, coating roller is too thick and not smooth.

3, the pressure of uneven size.

4, the coating is too large.

5, UV varnish poor leveling.

The solution: Reduce the viscosity of UV varnish, reduce the amount of coating. Pressure adjusted evenly. Coating roller should be ground, polished. Can add light leveling agent.


6- UN Varnish adhesion is not good


main reason:

1, printing ink surface crystallization.

2, printing ink in the auxiliary material is not suitable.

3, UV varnish itself lack of adhesion.

4, light curing conditions are not suitable.

The solution: printing process to consider polishing conditions in advance. Printed products need to be coated with primer oil to enhance adhesion.


7- thick UV varnish, a gel phenomenon


main reason:

1, UV Varnish storage time is too long.

2, Varnish failed to completely dark storage.

3, high storage temperature.

The solution: pay attention to the effective use of UV Varnish and dark storage strictly. Storage temperature to 5 ~ 25 is appropriate.


8-residual odor

main reason:

1, dry curing is not complete.

2, inadequate UV light or lamp aging.

3, UV Varnish poor resistance to oxygen interference.

4, UV varnish non-reactive diluent added too much.

Solution: UV varnish dry curing must be complete. And to strengthen the ventilation, if necessary, replace the UV varnish varieties.

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