Set off while printing on PVC using oil based Ink on Heidelberg Machines

Hi,

We are printing on PVC sheets using Oil based heat resistant inks on a Heidelberg offset machine. Post printing we also do a aqua varnish on the sheet. The sheet is then stretched or expanded post varnish. However during the printing process we are facing a problem of set off and also the inks are not scratch resistant post varnish.

We have tried using UV inks and UV Varnish but they tend to break when the sheet is stretched. Hence it does not work for us.

Please help on this.

Thanks

Mahesh

 

Hi,
If you want to print on such material, I recommend you to check the followings:
- Dampening solution should be ballanced precisely, in order to have minimum moisture on the plate and blanket.
- You should use special inks which are oil based but a little aggressive than conventional inks, so it's penetrating through the material.
- Try to use ink additives. They also help drying process.
- Finally, UV varnish at the end can protect the printed material.

Good luck,

 

Couple of things as Mathew mentioned,

You should use oxi dry inks that dry with oxidation. Conventional inks dry by Oxidation and penetration so you should look for the inks that are made for non absorptive substrates.
You can additionally add ink dryers in the ink.
If you are printing with alcohol, try to add upto 15% alcohol, this will help in drying process.
Run minimum water, just a little scum line at the leading edge of the plate.
Make low piles at delivery, approx 50 to 100 sheets.
You can PM me or email me at aqazi81 at gmail dot com for inks or dryers.

 

oxybind inks or high solids inks a MUST. Id recommend Dyne testing the substrate your printing on to insure its adhesion properties. As mentioned small lifts. Use a large micron sized powder. Id say at least 30 microns. Slow the press down, and be sure to deliver as smoothly as possible with the minimum blowdown air in the delivery. Even following all the listed suggestions your talking about a high risk job. The printer that does a once or twice a year run of these sort of jobs are really not equipped to do it profitably. If at all possible reduce your risk and send this type of work out to a specialty printer who has the experience and equipment to do the job properly.

 

We have been successful printing PET by using K+E F100 series inks, non-oil based, deliver in piles of 250 sheets maximum, it takes two days for curing, frequent airing the sheets and then lowering the pile to around 100 sheets in wooden crates to finally cut the large 50 X 70 cm sheets for die cutting in both a Minerva and SBG cylinder, the fountain solution is prepared for printing in a conventional dampening press with a drying enhancer of blue color called Feuerwassertrokenstoff. We also print a smaller 20" X 14" sheet in our GTOF. We rather print in the GTOF in one pass and endure the two days of idle time, however, the SORMZ 52 X 74 cm capability saves on paper, the largest cost issue of the job and we print a variety of label size.

The job comes every month. The material liner is highly sensitive to humidity in the press room, very prone to curling and it is very hard to cut in the guillotine, however, we have managed to perform the job profitably. However, it is better suited for flexo.

Good luck and keep us posted.

 

One thing I would add to the list of procedures would be to "not" use glycol based fountain solution or alcohol sub. Use only a solution comparable to "red etch" with alcohol.I have found this to be key in successfully printing on synthetic substrates along with the other procedures mentioned in other replies. Proper ink, large micron powder, small lifts,delivery set up, press speed and ample drying time with good press room conditions are all sound advice.