Bad drying:
phenomenon:
The ink has poor drying property and there is sticky ink on the cooling roller.
the reason:
<1> The surface temperature of the paper reaching the box is not high enough so that a considerable amount of solvent in the ink cannot be removed.
<2> The cooling effect of the web after printing is not good.
<3> The paper used has poor absorbency or the print has too much ink.
Countermeasures:
<1> Increase the paper surface temperature or reduce the print speed.
<2> Reduce the cooling drum temperature.
<3> Reduce the ink supply or use absorbent paper.
Paper breaks:
phenomenon:
The printed product will crack when folded.
the reason:
The oven temperature is too high and the paper is dehydrated.
Countermeasures:
Lower the oven temperature.
Poor friction resistance:
phenomenon:
The printed product is not resistant to rubbing and fades.
the reason:
<1> Low oven temperature thermosetting ink is not completely dry.
<2> The pH of the dampening solution is too low and the print is not drying properly.
<3> Strong Absorptivity of Paper Absorber
<4> There are few anti-friction additives in the ink.
Countermeasures:
<1> Raise the temperature of the oven to thoroughly dry the prints.
<2> Increase the pH of the fountain solution.
<3> Select moderately absorbent paper.
<4> Replace the new ink and add a rubbing aid afterwards.
Bad gloss:
phenomenon:
The print has insufficient brightness and low gloss.
the reason:
<1> The supply tank temperature is too high, resulting in thinning of the binder in the ink and excessive penetration of the paper.
<2> The print is not completely dry.
<3> Insufficient ink or low gloss of the paper itself.
Countermeasures:
<1> Lower the oven temperature and adjust the appropriate paper surface temperature.
<2> Adjust the temperature and printing speed so that the print is completely dry.
<3> Select high-gloss paper to increase the amount of ink in the print.
Ghosting:
phenomenon:
Two or more of the same prints appear on the print.
the reason:
<1> Mechanical ghosting: Loosening of the plate or blanket.
<2> Imprint overprinting is not allowed.
Countermeasures:
<1> Adjust the plate and blanket.
<2> Adjust the rules of the printing press to improve overprint accuracy and exchange overprinting sequence.
Uneven printing products:
phenomenon:
The unevenness of the printed product or the bound cross-section of the printed product is undulating.
the reason:
<1> The amount of printing water is too large to deform the printed product.
<2> The paper roll of the printing press has too much force to deform the paper.
Countermeasures:
<1> Reduce the amount of water when printing.
<2> Adjust the tension force of the printer tension roller.
---Tianjin Toyo Ink