Common problems and solutions of UV varnish of Kraft Paper Food Box

Common problems and solutions of UV varnish of Kraft Paper Food Box

First, the gloss is not good, the brightness is not enough

Main reason:

1. The viscosity of UV varnish of Kraft Paper Food Box 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. 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 of Kraft Paper Food Box according to the different conditions of the paper. For paper with strong penetration and absorption, a layer of primer can be applied first.

Second, the drying is not good, the light curing is not complete, and the surface is sticky

Main reason:

1. The intensity of UV light is not enough.

2. The UV lamp is aging and its strength is weakened.

3. The storage time of UV varnish of Kraft Paper Food Box is too long.

4. Too much diluent that does not participate in the reaction is added.

5. The machine is too fast.

    Solution: When the curing speed is required to be less than 0.5s, it is necessary to ensure that the power of the high-pressure mercury lamp is generally not less than 120w/cm, and the lamp tube should be updated in time, and do not wait for it to be broken before replacing it. If necessary, add a certain amount of UV varnish of Kraft Paper Food Box curing accelerator to accelerate drying.

3. The surface of the printed matter cannot be coated with UV varnish of Kraft Paper Food Box, and it becomes flowery

Main reason:

1. The viscosity of UV varnish of Kraft Paper Food Box is small and the coating is too thin.

2. The ink contains too much varnish or drying oil.

3. The ink surface has been crystallized.

4. There are many anti-stick materials (silicon oil, powder spraying) on the surface of the ink.

5. The glued mesh roller is too thin.

Solution: Corresponding measures must be taken when printing products that require UV varnish of Kraft Paper Food Box to create conditions. When applying UV varnish of Kraft Paper Food Box, apply a thicker coat. If necessary, you can solve the problem by applying primer or replacing special varnish.

Fourth, UV glazing coating has white spots and pinholes

Main reason:

1. The coating is too thin.

2. The anilox roller is too fine.

3. The amount of non-reactive diluent (such as ethanol) added is too much.

4. There is a lot of dust on the surface of the printed matter.

Solution: The production environment and the surface of the printed matter should be kept clean, and the coating thickness should be increased. A small amount of smoothing aid can also be added. Dilution is best to use reactive diluents that participate in the reaction.

5. The surface is unevenly coated, with streaks and orange peel.

Main reason:

1. The viscosity of UV varnish of Kraft Paper Food Box is too high.

2. The coating roller is too rough and not smooth.

3. The pressure is uneven.

4. The coating amount is too large.

5. The leveling property of UV varnish of Kraft Paper Food Box is poor. Solution: reduce the viscosity of UV varnish of Kraft Paper Food Box and reduce the coating amount. The pressure is adjusted evenly. The coating roller should be ground and polished. Light leveling agent can be added.

 Sixth, the adhesion of UN varnish is not good

Main reason:

1. The surface of the printed ink is crystallized.

2. The auxiliary materials in the printing ink are not suitable.

3. UV varnish of Kraft Paper Food Box 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 an adhesion-enhancing primer.

Seven, UV varnish of Kraft Paper Food Box thickens, there is a gel phenomenon

Main reason:

1. The storage time of UV varnish of Kraft Paper Food Box is too long.

2. Varnish is not completely protected from light storage.

3. The storage temperature is too high.

Solution: Pay attention to the effective use period of UV varnish of Kraft Paper Food Box and store it strictly in the dark. The storage temperature should be 5℃～25℃.

Eight, the residual odor is large

Main reason:

1. Incomplete drying and curing.

2. The UV light source is insufficient or the lamp tube is aging.

3. UV varnish of Kraft Paper Food Box has poor anti-oxidative interference ability.

4. Too much non-reactive diluent in UV varnish of Kraft Paper Food Box.

Solution: The drying and curing of UV varnish of Kraft Paper Food Box must be thorough. And to strengthen ventilation, if necessary, replace the variety of UV varnish of Kraft Paper Food Box.

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