Whitening phenomenon treatment of printing ink film
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1 point whitening. The main reason is that the ink system is poor in the mutual solubility of the wax surfactants; the second is because the ink printing process is not reconstituted and the ink is transferred to the image.
Treatment method: An aromatic hydrocarbon or ester true solvent should be added to promote its dissolution. Or install a stirrer in the ink fountain (such as plastic pipe, put it on the outside with unprinted plastic film, then tie the two ends tightly in the ink head to stir the ink randomly), or add anti-ink during the ink manufacturing. Oxygen treatment.
2 point white point. The main cause is ink static or substrate static electricity. Or caused by the static electricity generated by the dilution solvent (the resistance is different due to different solvents). Usually occurs when the temperature is high or the printing speed is fast. Secondly, when the film is laminated, it is loose or loose before the front, and the static electricity is often caused by the humidity.
Treatment method: It can increase the amount of antistatic agent in the ink (the excess affects the composite fastness), select the solvent with less resistance to dilute the ink, and adjust the grounding and receiving ground wire (the general depth is 700 ~ 1500 mm).
3 crack type whitening. The main reason is that the ink transfer performance is too poor, and the second is that the printing pattern is too shallow and the solvent in the ink system is easily evaporated too quickly.
Generally, the roughness of the imprinting leads to poor film formation, especially the whitening of the ink system or the ink fountain diluent which is absorbed by the inhalation of water, and most of them occur in an environment where the humidity in the workshop is too high in summer.
Treatment method: replace the transferable ink or replace the deeper printing plate, and the third one is added to the slow dry solvent treatment.
4 whitening of the whole block. The main reason is that in the continuous printing time is too long, the operator repeatedly adds a single solvent when the viscosity of the ink becomes sticky or thick, thereby breaking the balance of the volatilization of the mixed solvent in the original ink system, resulting in printing ink. The ink layer is rough and white when filming. Second, even if the operator adds a mixed solvent, excessive addition tends to relatively reduce the content of the synthetic resin in the ink, and the above-mentioned whitening phenomenon also occurs. Treatment method: First, add 3% to 7% of slow-drying solvent, especially the true solvent that can plasticize the ink to resist the invasion of water molecules; the second is to use a special thinner containing resin; the third is to add 5 in the ink %~15% varnish to overcome whitening caused by insufficient resin content. Fourthly, install a central air conditioner that can regulate temperature and humidity in the workshop or use a moisture absorber to eliminate it.