[Discussion] When printing black on clear BOPP film, some characters in the light screen areas are not clear. How should this be solved?
- When printing black on clear BOPP film with gravure lamination ink, unclear characters in light screen areas were attributed to dry plate, poor transfer in light screen areas, plate clogging, and plate scumming.
- For dry plate, add slow-drying solvent or fresh ink to the black ink; for ester-soluble ink, add isopropyl alcohol when adding solvent and avoid running the printing speed too fast.
- The printing speed in this case was 100 m/min; one suggestion was to add butyl acetate, while another explicitly advised against butyl acetate and recommended isopropyl alcohol instead.
- The company was currently using toluene, ethyl acetate, and methyl ethyl ketone as solvents.
- Shallow engraving of dots in the light screen area on a new plate may cause this phenomenon, and new plates generally have more problems, with similar issues disappearing after longer use.
Heliansheng Packaging Materials: When using gravure lamination ink to print on clear BOPP film, some characters in the light screen areas are not clear when printing black. How should this be solved?
Yu Ke, Printing & Lamination: This is caused by dry plate. Add some slow-drying solvent to the black ink. Or add some new ink; if it is an ester-soluble ink, add isopropyl alcohol when adding solvent. At the same time, do not run the printing speed too fast.
Heliansheng Packaging Materials: Could it be a problem with the ink itself?
Yu Ke, Printing & Lamination: It should not be an ink problem.
Deng, Ink Engineering: Your problem is either dry plate or poor ink fluidity. What is your machine speed?
Heliansheng Packaging Materials: 100m/min.
Deng, Ink Engineering: Then dry plate is more likely. Add some butyl acetate.
Yu Ke, Printing & Lamination: It is best not to add butyl acetate; add isopropyl alcohol.
Heliansheng Packaging Materials: Currently we add toluene, ethyl acetate, and methyl ethyl ketone.
Deng, Ink Engineering: The most direct causes are poor transfer in the light screen areas, plate clogging, and plate scumming.
Heliansheng Packaging Materials: When we print, there is one place with a block of small characters in a light screen. Every time we print, the last few characters are blurry, always in the same place. There is no problem with the plate cylinder.
Deng, Ink Engineering: Is it a new plate?
Heliansheng Packaging Materials: Yes.
Deng, Ink Engineering: The dots in this area being engraved too shallowly may also cause this phenomenon.
Heliansheng Packaging Materials: The plate is engraved very evenly.
Deng, Ink Engineering: New plates generally have more problems; after being used for a long time, there are no similar problems.
Heliansheng Packaging Materials: So there are three possibilities: the plate is engraved too shallowly, the ink fluidity is not good enough, and dry plate, right?
Deng, Ink Engineering: Right.
Huang Chuan, Printing: It may also be that the solvent is not properly mixed and the doctor blade angle is not properly adjusted. You can rule these out one by one to find a solution. (From the Packaging Frontier flexible packaging technology QQ group. You are welcome to join: Main group: 121451012; Group I: 64311965; Group II: 37848282; Group III: 119411638; Group IV: 116162302; Group V: 256925591. For more technical content, see the bimonthly magazine Packaging Frontier. Subscriptions welcome: Mr. Xie: 020~85626447/605, 13310896471. For more content, visit the Packaging Frontier website www.pack168.com.)
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