Kraft liner curling

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Kraft liner curling

Postby wdustin1 » Wed May 08, 2019 9:34 am

Hello everybody!

We are having a issue with a white polyprop material that has a Kraft liner. We are fan folding it and it curls really bad during its run through the press, my assumption is the humidity in the air, it has been raining non stop for the past week. I thought about grabbing one of out industrial dehumidifier but the shop floor is pretty big i don't think it will be able to do much. Has anybody every tried to coat the backside of the liner to maybe keep it from drawing in so much moisture? We tried using the U.V. lamps to dry it out through its run through the press but the press lamps just don't put off enough heat. any ideas? Thanks!
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Re: Kraft liner curling

Postby Leadpress » Wed May 08, 2019 10:39 am

wdustin1

Don't use UV lamps on it. It only makes the curling worse. Is your material curling upward? Too much tension on rewind. Try not to make your rolls larger than 3500 feet and cover them with a shrink wrap at the press as you're taking the roll off; this will help with humidity. No heaters, and absolutely no UV lamps. Are you printing on it??? If so, try to use as little heat as possible to dry if it's water base; one heater? If UV, only one lamp, at the very beginning of the press and the lowest intensity possible without compromising curing. Hope some of this helps.
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Re: Kraft liner curling

Postby Leadpress » Wed May 08, 2019 10:43 am

another thing you can try is, if you are attempting to coat it first, use the corona treater before you coat it. Run the coating on your third station if you have over three print stations. How wide is the web?? If wide,. 12"+ turn on the first two lamps before coating and use two lamps after it, but not too high intensity.
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Re: Kraft liner curling

Postby wdustin1 » Wed May 08, 2019 1:25 pm

Its a blank die cut job, we print a trigger mark on the back of the liner and that's it, I was only thinking about a coating to keep it from drawing in moisture. I have the rewind tensions next to nothing it is curling up towards the face. I tried a delam relam and it didn't help, its just the liner curling terribly.
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Re: Kraft liner curling

Postby donaldwal » Wed May 08, 2019 8:56 pm

Do they make a lay flat Kraft liner? We run a 14 inch sheeted poly blank and we had to go to a heavy lay flat liner to prevent or reduce the curl. I know your fan folding but the heavier liner may help.
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