Ink Adhesion Fails, after Exposed to Icy Water

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Ink Adhesion Fails, after Exposed to Icy Water

Postby Frank Burgos » Sun Sep 13, 2015 9:17 am

Hi Folks,

A client is printing on PP for soft drink bottles. The ink passes the tape test, after printing, but the ink easily scratches off after the label, on a bottle, has been immersed in a chest of icy water.

We have had posts on this forum about poor adhesion, but not with these specifics. It's been a while, too, so I am posting a fresh one.

They are treating inline, printing with UV white and colors on top. Treat level is not tested beyond 40 dynes, using only pass/fail markers. After the ice chest, ink scratches off.

Different substrates and inks are being brought in, as are dyne level testing solutions, up t 50 or 52 dynes.

Your thoughts are welcome!

best regards,
Frank
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Re: Ink Adhesion Fails, after Exposed to Icy Water

Postby inkman » Sun Sep 13, 2015 2:19 pm

I have never seen this problem with UV inks, but I suspect the mechanism is the same for all inks. This phenomenon is also common with even solvent based inks, and especially with water based inks, on treated polyethylene for outdoor bags. What appears to be happening is that prolonged exposure to water appears to break the ionic bond between ink and substrate surface. So, even ink systems that typically have very good adhesion and water resistance will often fail this test. If the film supplier cannot provide a more ink receptive substrate, it might be advisable to look at ink systems from different suppliers. Increasing dyne level should help, particularly the polar component. A test that correlates to actual exposure conditions will need to be devised, if not done already, and substrate samples for the actual job will need to be provided to ink suppliers.
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Re: Ink Adhesion Fails, after Exposed to Icy Water

Postby guy de cafmeyer » Wed Sep 16, 2015 1:43 am

It is an ink system problem ; ie. Ink should pass a deepfreeze test at least .
The ink maker should be able to correct this . .
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Re: Ink Adhesion Fails, after Exposed to Icy Water

Postby Frank Burgos » Fri Sep 18, 2015 12:51 pm

Thanks guys. Very helpful.
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Re: Ink Adhesion Fails, after Exposed to Icy Water

Postby longtimefan » Sun May 08, 2016 2:01 am

Late to this, but..

Someone said to to ink rep.. Can you add a wax to the ink? Can you put a over print varnish on?
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Re: Ink Adhesion Fails, after Exposed to Icy Water

Postby Katherine » Mon Jun 11, 2018 1:33 pm

We don't work with unsupported plastic, but is laminating an option? For our Flexo and HP runs, I would probably recommend Laminate, but this is a different material/market.
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Re: Ink Adhesion Fails, after Exposed to Icy Water

Postby KF » Wed Jun 13, 2018 1:44 pm

Actually it doesn't need to be icy water, any temp. will do it. UV ink will pass tape and scratch tests right off of Press but will fail after being exposed to water. After the ink dries it will return to a state that regains it's adhesion once again. I believe it's as InkMan stated that it's breaking the ionic bonds. The only way I know to stop it is to print a catalyzed waterbased varnish in between the inks and the UV OPV or as a last down OPV if no other varnish is being used.
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