6. Adhesion
Coiled immediately after printing, the ink and film adhere to each other, or the ink sticks to the opposite side of another film.
the reason:
(1) Bad drying.
(2) As the temperature rises, the ink partially softens.
(3) The winding is too tight.
(4) Insufficient ink adhesion.
(5) The affinity between ink and non-printing surface is too strong.
Solution:
(1) Weakening the coiling pressure.
(2) Cool sufficiently before coiling.
(3) Make the ink sufficiently dry.
(4) Design layout of graphics and texts that are not affected by roll pressure.
(5) Use quick-drying thinner to increase ink drying speed.
(6) Appropriate use of antiblocking additives.
(7) Reduce the wetting tension of the non-printed surface.
7. Electrostatic fault
Electrostatic failure refers to whiskered ink caused by static electricity. If the electrostatic whisker ink occurs on the bar of the bar code, the edge roughness of the bar will not meet the requirements and the reading effect will be affected.
Cause: The plastic film is a poor conductor of electricity and generates static electricity in the printing process (moving, rubbing, peeling, etc.) that affects the transfer of ink. Electrostatic faults often occur in dry winter months.
Solution:
(1) Using static eliminators;
(2) Sprinkle water in the printing shop or use an air humidifier to increase the humidity;
(3) Eliminating electrostatic grounding on the guide roller. (Although the guide roller is a good conductor of electricity, the lubricant in the bearing tends to turn the guide roller back into an insulator.)
(4) Improve the working viscosity of the printing ink.
(5) Ground immediately after printing.
(6) Contact the film and ink manufacturer to add an appropriate amount of antistatic agent to the ingredients. (Excessive use of antistatic agents will affect the fastness and composite strength of the ink).
Bad size
In the process of printing and post-press compound bag making, if the processing conditions are not suitable, such as too high drying temperature and too much tension, the film will be deformed to stretch or shrink, and accordingly the bar code will also be deformed. Especially for stretchable films such as polyethylene, special attention should be paid.
the reason:
(1) Improper process conditions such as film tension.
(2) Bad film flatness.
(3) Roller roll accuracy is poor.
Solution:
(1) Accurately adjust the tension of the retracting roll to avoid film stretching
(2) Adjust the diameter difference of the roller and adapt the tension.
(3) Replace wrinkles or membranes with lotus leaves
(4) Confirm the accuracy, circumferential accuracy and parallelism of the roller.
From "Guangdong Packaging" Author: Shiraki