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teebc123
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Join Date: Nov 2007
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Ink Smearing At Printing Process

01/13/2008 10:37 PM

Hi!

I would like to know what is the main cause of the ink smearing problem at gravure printing process for flexible plastic films such as BOPP film.

The ink look like to spear out with very thin hairy lines. Method such as put in static eliminator during the process but not realy overcome the problem.

Could someone advise what other method else should either on the raw material; BOPP film or additive to be add to the ink ...........

Thanks in advance!
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aurizon
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#1

Re: Ink Smearing At Printing Process

01/14/2008 11:33 PM

flexo inks are a black art. Find an inkmaker who has solved this problem and buy his inks.

the whole field is full of trade secrets and valuable information is closely guarded.

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Snaketails
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#2

Re: Ink Smearing At Printing Process

01/14/2008 11:38 PM

Have you checked that the ink is of the type specified by the manufacturer?

That when the ink is transferred onto the plate, then onto the surface, that your not getting "strings" between the plate and the material your printing the design on to?

Is this a new installation, or is it a current machine in operation that has started to play up on you?

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#3

Re: Ink Smearing At Printing Process

01/15/2008 6:48 AM

You may have a drying problem. To accelerate drying, especially in a humid climate I've had to add acteone to our ink.

What treat level are you running the film at?

Are you using solvent or water based inks?
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ca1ic0cat
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#4

Re: Ink Smearing At Printing Process

01/15/2008 7:25 AM

Could be a viscosity problem. Or a surface tension problem. Static charge could contribute, but you seem to have fixed that problem.

I'll agree with aurizon, you need to get a good inkmaker and a press operator together to sort this out. It's not as easy as it looks.

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double_j_b
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#5

Re: Ink Smearing At Printing Process

01/15/2008 7:31 AM

Sounds like a viscosity problem you may need to thin the ink to reduce the viscosity.

It has been a while since i worked in a gravure facility but i think you looking for a 5-10 second drip out on a #2 Zonn cup, so pretty thin.

Also you might want to check out your doctor blades to see if they are worn. Since you are using etched cylinders the doctor blade will wear pretty quickly and require replacement every 50,000 feet of material.

Gravure printing is very dependant upon the viscosity and quality of the inks used. The cylinder etching is very precise and the ink fill must be fluid enough to be readily removed by the doctor blade assembly. also the angle of the doctor blade assembly can have a great effect on this as well. To much steep an angle and the blade chatters and ruins the cylinder, to flat and the ink can lift it and go under creating streaks as well.

One other thing to look for would be ink gathering at the opening of the dryer. Since this is a high speed process and there is a lot of ink vapor created it can build up on the inlet to the dryer creating little bumps that the material can flutter into and create streaks just before the ink dries.

Hope this is helpful.

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ronald
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#6

Re: Ink Smearing At Printing Process

01/15/2008 9:52 AM

I have worked with Zebra printers for labels and I had seen the same problem. I agree with the other members; it looks to me you have to thin-out the ink a little. If it's too viscous it will "float on the medium". Drying time will be extended and it will smear and spread.

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#7

Re: Ink Smearing At Printing Process

01/15/2008 6:12 PM

Check speed match of applicator to web speed or possibly the ink viscosity is too high.
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Carpe Diem
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#8
In reply to #7

Re: Ink Smearing At Printing Process

02/24/2009 9:50 AM

Hello Gentlemen,

I'm not in the printing business, but have worked with them from time to time.

One of the main problems I hear is the effects of temperature in the room. This effects web feed, drying time and viscosity of the ink.

If you can control a variable, then printing becomes easier and more cost effective. Most of the time the pressmen play catch up with the effects of temperature where the liquid is thick at cold temps and more viscous at higher temps.

Install a inline viscosity sensor to monitor the ink viscosity and control the temperature of the ink with a bath.

www.cambridgeviscosity.com has solved this problem.

Good luck

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Anonymous Poster (2); aurizon (1); ca1ic0cat (1); Carpe Diem (1); double_j_b (1); ronald (1); Snaketails (1)

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