Ink Adhesion Issues

[NZOC]

We are running the Fujifilm Acuity Select 4006 flat bed and having issues with ink adhesion on rigid polypropylene. Ink scratches off very easily even after being left overnight.

UV lamps turned to max. Uvijet adhesion master used but made minimal improvement. Using Uvijet KI inks.

Something I'm missing or is this normal?

 

[Cornishpastythighs]

Have you checked the Dyne level of the substrate. was it Corona treated prior to printing. Turing up the lamps may not help as 'cure' and 'adhesion' are two separate issues

 

[NZOC]

Have you checked the Dyne level of the substrate. was it Corona treated prior to printing. Turing up the lamps may not help as 'cure' and 'adhesion' are two separate issues

The material is the same that we have had other companies print on prior to getting our own machine, it hasn't been treated.

 

[aqazi81]

The material is the same that we have had other companies print on prior to getting our own machine, it hasn't been treated.

Even though the material is same but the surface tension may have increased due to lack of corona treatment or if its an old stock. Usually corona treatment last not more than a year. If this is the case , the ink will not adhere to the substrate even though the ink is cured properly.

 

[D Ink Man]

Could be an over cure. Using the MEK test could help you to see if you are curing the print properly. Using MEK and a cotton swab stroke 20-25 times to see if ink is removed. Less than 20 strokes is under cure and over 25 strokes is over cure. One back and forth stroke counts as one.

D Ink Man

 

[9162]

Even though the material is same but the surface tension may have increased due to lack of corona treatment or if its an old stock. Usually corona treatment last not more than a year. If this is the case , the ink will not adhere to the substrate even though the ink is cured properly.

cant ever assume treatment has not gone past time. to me sounds like the need for fresh stock

 

[NZOC]

So, still having major issues with adhesion on Polypropylene and in particular with the white ink. Not having a lot of luck with the Fuji people as they can't seem to give an answer. This isn't an issue with the material as it's fresh material, and still an issue even after using adhesion promoter. Another issue is the ink still feeling sticky even a few days after printing.

 

[Cornishpastythighs]

Maybe get some of these to measure the dose of UV you are getting, just because you turn the lamps up does not mean you are getting efficient dose, I have used these before and they highlighted so issues at the outside edges of our lamps

https://www.uvprocess.com/uv-intensity-labels/1971-uv-fastcheck-strips.html

 

[Cornishpastythighs]

Here's some info on 'Doped' UV lamps, we used these for Opaque Whites

https://www.alpha-cure.com/technical...ctral-outputs/

 

[Seeking Knowledge]

Hello NZOC,

UV ink is an interesting animal, manufactures of ink try to make so it adheres to a wide variety of materials/substrates, since it is not cost effective to swap out ink in a digital printer. This can cause some issues, where you say it feels sticky, this may be because the ink series you are using is a flexible ink. I know Fuji has several ink series for their digital machines. Some are more flexible than others, some are more hard curing, it kind of depends on the majority of your work for which ink series you choose.

It is strange that an adhesion promoter would not help but it may be it is not the proper one for the material you are printing on.

A couple of suggestions, 1- try wiping an area of your sheet with Isopropyl Alcohol. If the sheets surface has contamination, plasticizer migration, this wipe will remove it and should help with adhesion. If the wipe helps, your stock is old and a Dyne test would show this too, but my guess is you do not have a testing kit. 2- increase the number of passes and if you can make sure the lamp is on the lead edge of the print head is on too, this can help. 3- have you tried flipping the sheet over and seeing if the adhesion is better on the other side?

SK

 

[NZOC]

Maybe get some of these to measure the dose of UV you are getting, just because you turn the lamps up does not mean you are getting efficient dose, I have used these before and they highlighted so issues at the outside edges of our lamps

https://www.uvprocess.com/uv-intensity-labels/1971-uv-fastcheck-strips.html

Interesting. Might look at getting these. Thanks.

 

[NZOC]

Here's some info on 'Doped' UV lamps, we used these for Opaque Whites

https://www.alpha-cure.com/technical...ctral-outputs/

Will consider upgrading the lamps when these ones need replacing, won't be for a while though as the machine is only about 6 months old.

 

[NZOC]

Hello NZOC,

UV ink is an interesting animal, manufactures of ink try to make so it adheres to a wide variety of materials/substrates, since it is not cost effective to swap out ink in a digital printer. This can cause some issues, where you say it feels sticky, this may be because the ink series you are using is a flexible ink. I know Fuji has several ink series for their digital machines. Some are more flexible than others, some are more hard curing, it kind of depends on the majority of your work for which ink series you choose.

It is strange that an adhesion promoter would not help but it may be it is not the proper one for the material you are printing on.

A couple of suggestions, 1- try wiping an area of your sheet with Isopropyl Alcohol. If the sheets surface has contamination, plasticizer migration, this wipe will remove it and should help with adhesion. If the wipe helps, your stock is old and a Dyne test would show this too, but my guess is you do not have a testing kit. 2- increase the number of passes and if you can make sure the lamp is on the lead edge of the print head is on too, this can help. 3- have you tried flipping the sheet over and seeing if the adhesion is better on the other side?

SK

Yeah, there are other Fuji inks that are better but unfortunately Fuji NZ don't supply them in New Zealand. We could get them in at a cost but a cost we need to avoid at present. We are using KI, KN is apparently much better, but more difficult to work with.
1/ Have tried using IPA - Minimal improvement.
2/ Both lamps always on. More passes puts down more ink which reduces adhesion.
3/ Yeah. Both sides. Same result, although some colours do have a rougher side which does adhere better.

 

[NZOC]

Have been asking around and other companies have had the same issues/struggles we are having with this material. Fuji themselves have admitted this is an issue they are aware of and there isn't much that can be done. Their white ink just isn't compatible with polypropylene.

We have found reducing the white linearization curve to put down less ink has made a significant improvement, although can reduce the brightness and quality of the print obviously but is acceptable for some of the work we are doing. Currently running a job now at 65% and so far so good. Most other colours adhere well, it is only white that is the issue.

One experiment I tried last week, and will try again when I have the chance, is to put a layer of colour down under the white. In this case I put a layer of 50% yellow with the white on top. The yellow adhered to the material perfectly and the white adhered to the yellow. Yes this process will use more ink and take a little longer which could be an issue on larger production runs, but if it works would be great for smaller runs at least. Will try again with maybe 25% magenta or something later.

 

[PrinterB]

You should try using an UV adhesion promoter this will help with ink adhesion. Rigid polypropylene is difficult to print even with solvent based screen and pad printing ink. UV inks would also be much harder to print with. The reason for this is because of the Low surface energy of the material. For the UV ink to adhere well, you must increase the surface energy of the material. This is where the adhesion promoter such as PP Primer come in handy.