UV Printing on Silver Laminated boards ( Tape test failures)

[bibu.sridhar]

Hi All,

We have a 6 color CD 102 UV machine with 2 intermediate UV lamps and 3 delivery UV lamps. When ever we try to print on silver laminated duples boards, we have issues of ink peeling off ( Tape testing fail).Sometimes its not happening on all the sheets.
What is the best solution to make sure the ink sits on the surface well..

Note - At the moment we are coating the sheets with a water based primer and then printing on top of this. Although this solves the problem, it results in 2 main issues.
* No. of impresssion is double
* Plate wear off within 2000 impressions.

Could some one help find a better solution / solutions for this.

Regards
Ahlia

 

[Cornishpastythighs]

Printing a Prima coat is one way to ensure you get good ink adhesion to foil or plastic, the main issue is around having your substrate treated prior to printing to make sure the ink sticks/bonds. There are various ways to treat the stock Corona treating is probably the most common. Corona treaters can be installed right on your press if you are printing on non absorbant stocks day in and day out. You must check that your stock has the correct surface tension to hold onto the ink and this is usually done using a Dynes pen or fluid. I think the target is 40 Dynes or higher. Most ink companies will supply a High adhesion ink series but be careful with your rollers as this ink is pretty aggressive. Check your UV lamps are in all functioning 100% but dont confuse 'cure' with adhesion. you can have great ink cure but the ink still wont stick to the substrate.

 

[bibu.sridhar]

Thanks mite,

Can u detail me on corona treating online.....if it is to be installed on the press....i think instead of 6 units we could only use 5 units.....
At the moment we are trying to get the foils with 42 + dynes......but since the foils doesnot have any name or technical details its hard to confirm the lots are same...
Also most of the time..may be the first few sheets are ok but ink peel off happens in between...
Your comments appreciated

 

[chevalier]

You must check that your stock has the correct surface tension to hold onto the ink and this is usually done using a Dynes pen or fluid.

This is most likely the issue. As he mentioned primer coating or other pre-treatement is the best resolution to this problem. Depending on who applied the foil to the sheet, what type of foil they applied and how they applied it makes a big difference. We experimented with in-house hot-stamping with "printable" foil and then printing upon it with disastrous results. We played with different inks, replaced UV lamps, cleaned UV system components diligently and still did not have optimal results. The surface simply did not have enough tension for the inks to bond to. We do not have the same problems with our poly metal vendor nor do we have to pretreat.

 

[Cornishpastythighs]

Here's a link to some information regarding sheetfed surface treating
Enercon launches automated sheetfed corona treater | Labels and Labeling
Corona treatment effects are reduced over time so if your substrate is treated by your supplier and stored for a long period of time it can lose its effectiveness. Likewise if the sheets are sitting around in your place. You have to check the Dynes of each load prior to running through the press to ensure the surface tension is ok. If you have a jogger/aerator then pull sheets from various spots throughout the load and check surface tensions prior to printing.
Have your supplier in for a visit and show them the issue and have them provide some recommendations.