UV varnish is also called ultraviolet varnish or curing varnish. The main components of UV varnish are composed of photosensitive resin, reactive diluent, photoinitiator and additives. The principle is that under a certain wavelength of ultraviolet radiation, the system initiates light The free radical of the agent initiates the unsaturated double bond in the resin, and the key-lock polymerization reaction occurs rapidly, so that the cross-linked junction film is cured.
Its advantages are: fast glazing speed, high brightness of the film layer, firm film surface after drying, high production efficiency, small occupied space, good mechanical and heat resistance, cold resistance, water resistance, wear resistance and other properties, good It has a protective effect. After glazing, it can make the surface of the printed product very bright and smooth. The refraction effect makes the picture and text produce a strong three-dimensional sense, the colors are more vivid, and the printed product has a high-end sense.
The disadvantage is that the UV oil has a high degree of polymerization, poor surface molecular polarity, and no capillary pores, so the UV film layer has poor affinity.
The following problems are common:
1. "Pocket"
the reason:
a. The ink has crystallized.
b. The surface tension value is large, and the wetting effect of the ink layer is not good.
solve:
a. Add 5% lactic acid to the UV oil to destroy the Changhua membrane, remove oil or deburr.
b. Lower the surface tension value, add surfactant or solvent with lower surface tension value.
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2. Streaks and wrinkles
Reason: The UV oil is too thick and the coating amount is too large, mainly appearing in the roller coating.
Solution: Reduce the viscosity value of the UV oil and dilute with an appropriate amount of alcohol solvent.
3. Orange peel
the reason:
a. UV oil has high viscosity and poor leveling.
b. The coating roller is too rough and unsmooth and the coating amount is too large.
c. The pressure is uneven.
solve:
a. Reduce the viscosity, enter the leveling agent and appropriate solvent.
b. Use thin coating roller and reduce coating amount.
c. Adjust the pressure.
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4. Sticky
the reason:
a. The ultraviolet light intensity is insufficient or the machine speed is too fast.
b. The storage time of UV varnish is too long.
c. Add too much diluent that does not participate in the reaction.
solve:
a. When the curing speed is less than 0.5 seconds machine speed, the ultraviolet light power should not be less than 120w / cm.
b. Add a certain amount of UV varnish curing accelerator or replace the varnish.
c. Pay attention to the rational use of thinner.
5. Can not be painted or flower
the reason:
a. Crystallized oil and powder spraying are produced on the surface of the printed matter ink.
b. Too much ink and dry oil are mixed in the ink.
c. The viscosity of UV varnish is too low or the coating is too thin.
d. The anilox roller is too thin.
e. Light curing conditions are not suitable.
f. Poor adhesion of UV varnish itself and poor adhesion of printed materials.
solve:
a. Eliminate the crystallized layer, roughen, remove grease or add 5% lactic acid.
b. Select the ink auxiliary material that matches the UV oil process parameters, or wipe with a cloth.
c. Use UV varnish with high viscosity to increase the coating amount.
d. Replace with anilox roller matching the UV varnish.
e. Check if the UV lamp tube is aging or the machine speed does not match, select the appropriate drying conditions.
f. Apply primer or replace special UV varnish or choose good surface performance.
With the improvement of people's consumption level and the enhancement of consumption ability, essential oil as the production of daily chemical products for keeping the human body relax and beauty, have been unprecedentedly developed, and the competition in the cosmetic market is becoming more and more fierce. In order to better publicize their products, the manufacturers have different classification and packaging of cosmetics for their own characteristics.
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