Cause analysis of yellowing phenomenon in the most

Analysis of the causes of yellowing in UV glazing prints

ink using UV glazing "> printing materials sometimes appear yellowing, which is mainly caused by two reasons: first, the UV glazing oil itself turns yellow; second, in the glazing process, the glazing oil only solidifies on the surface of the printing material. The interior is not completely cured.

the yellowing of the glazing oil is related to the fact that the oligomer and active diluent used have a certain yellow, so colorless oligomer and active diluent should be selected to prepare the glazing oil. In addition, the influence of photoinitiator is also Very large, some photoinitiators will make the system yellow after curing, such as benzoin dimethyl ether, so we should avoid using this kind of photoinitiator to prepare varnish

in the glazing process, when the interior of the glazing oil is not completely cured, the internal glazing oil diluent will gradually be absorbed by the ink and paper, and will act on the binder in the ink, resulting in the loss of grease When the surface material is not adequately protected, the pigment particles are free At this time, the smoothness of the paper coating and ink layer surface will be reduced by Liansi's complete and systematic new product development method. The rough surface will produce diffuse reflection of light, which will add some white components to the color, making the brightness increase and the saturation decrease, giving people the feeling of overall yellowing and color fading. Therefore, we should improve the curing speed of UV varnish or choose an efficient UV curing light source. In addition, the use of water-based UV varnish can avoid the chemical action of diluent Liu ink layer and paper coating, and can avoid the yellowing of printed matter

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