Printing with Xylene borne inks, non-textile

[ZooCity]

We are ready to r&d a silicone ink on some client samples of sil product but I'm in the dark about xylene and using inks borne in it.  Anyone care to share a little experience with it? 

My big questions were: 

photopolmer emlusion ok?

mesh recommendation?

do you simply thin/retard with xylene?

This stuff is flammable- how flammable? Any special precautions needed?  We were planning to give it the recommended 5min cure at 302˚F in our TexAir since it has a 10' chamber and tons of airflow.  But it's kind of an open environment inside that dryer so I was a little concerned about spark ignition and a potential big ol dryer fire if it caught some lint in the flash.   Our dryer is pretty clean and the exhaust system really moves the air rapidly but, you know, can't be too careful. 

Mfg has a tech sheet but it's pretty sparse on the hard information.  Thx in advance.

[balloonguy]

I use some nazdar inks that are pretty flammable. We use laquer thinner to thin and clean them.
I would not run anything with solvents through the dryer. We use hair dryers all the time. I actually put them in multiple printed heads and let things dry as they go around the press. When we were still printing on a manual I had 4 - 5 dryers hanging from the ceiling and I would put those items under they dryers. Once you have a good pace going you can do 300 - 500 and hour depending on the ink coverage. The 7200 series in we use says that it needs 20 minutes top dry. We get it done in 30 second with a hair dryer. We also use 305 or higher mesh on those.
I have used qx1 and it was fine. I prefer proclaim though.
Matt

[Frog]

I have cleaned enamels, poster, (and plastiso) inks with xylene, but always used the recommended ink-specific thinners and retarders. Enamels, I may have used mineral spirits to thin, never xylelne. Posters and signs were either racked and air dried in my operation, or sent through electric and/or gas dryers in shops in which I worked.
The MSDS should list flammability.

Emulsion tech sheets should list compatibility with solvent inks.

[mraph]

the other concern you asked was the effect on Phtopoymer emulsions.
this is a concern most photo-polymer emulsions are not solvent resistant , and will break down or at the very least lock the emulsion in
this is not just with xylene, but any low flash "hot solvents" solvent IE: min spirits, screen opener, laquer thinner, even some commercial press washes contain low flash "hot solvents".

hope this helps

alan

[Frog]

Alan just pointed out a possible side effect of solvents and solvent based inks on the wrong emulsion is to lock them in.

In this vein, remember that xylene was actually used as a seat-of-the-pants common ingredient off label use as a stencil hardener.
This is greatly exacerbated by the still-too-common condition of underexposure either by incorrect calculation, or on purpose in a misguided, effort to hold fine detail.

[Inkworks]

Jumping into printing silicone ink is a pretty big jump if you haven't messed with solvent based inks before. That's not to say you can't or shouldn't.

You'll want some of the recommended thinner for the ink, and hopefully some retarder. Xylene is a medium-slow thinner in most inks, Lacquer thinner is extremely fast.

You'll probably want to flood between prints, as long as you're moving fairly quickly and haven't over thinned or over retarded the ink. If you can move quickly enough you may get by without a flood in between.

You'll want a suitable fast thinner on hand along with gloves and rags in case the ink dries in the screen. We use Lacquer thinner for clean-up for all of our solvent based inks, but I'm not sure if it's compatible with the silicone ink you'll be using.

We dried solvent based inks through our electric conveyor dryers all day every day for decades without incident, including full flood background prints, never even a concern. The ovens were vented.

We've never experienced lacquer thinner or the thinners made for vinyl, MP, conductive, Coroplast, or epoxy inks locking emulsion in the screens, but we've always used dual cure emulsions (Autotype 8000 and the like.)

[ZooCity]

Thanks everyone.  I am going to run these through the TexAir.  We're talking about a max image of 3"x4".  Although there could be many of them on the belt at once I don't think it would be enough solvent airborne to cause a major problem, especially since there is more than adequate ventilation in this dryer. 

Inkworks- they didn't really give me a specific answer on what solvent to thin/clean up with but I'm drilling them for a hard answer.  The answer I got was:

It is recommended to use solvents with low Sulfur content since Sulfur can inhibit the platinum catalyst.  If you are using of the shelf solvents, I suggest doing a small side experiment where you add the solvent to the individual parts (particularly the Part A, since that’s the side the Catalyst is on) and let it sit overnight.  Mix it up the following morning and see if it still cures up well.  If it does, you should be good to go.

Can I use off-the-shelf Xylene for thinning (slow thinner) and the lacq thinner for wipe down in the event of dry in?   

They have no recommended retarder, which is a bummer but they are open to developing one if needed.  I guess I'll just hope it's not necessary. 

We'll just have to see if the Aquasol holds up to it.  I have a box of Chromaline MagnaCure 38µ that I need to run through if not though I worry about delamination. Print runs will be in the 150-350 pc range on avg.

[Inkworks]

Yikes, so you're printing catalyzed silicone...

I've used it for pouring my own pad printing pads, but I've never printed it.

okay, my printing experience is out the door on that one, so the best I can do if is give you edumacated guesses.

Remember with catalyzed inks "dry" and "cured" are two different things. Dry refers to the flashing off of the thinners in the print, Cured refers to the completion of the catalyzation, which can be minutes, hours or days depending on the chemistry.

Sounds like it will be thinned with Xylene to make it more fluid and allow flash-off of the solvents to keep the print in place while it catalyzes. Be aware that heat-curing could cause the image to flow/bleed as many catalyzed products go through a temporary decrease in viscosity when heated, followed by an accelerated cure as the heat speeds up the chemical reaction. Your silicone should be thick enough to resist this, but if it happens, it's nice to know why and you could maybe explore rack-drying.

Clean-up is a guess at best,  I'd start with lacquer thinner, but be prepared to use Xylene as a back-up. If Xylene thins it, it should be good for clean-up too, but it's such a slow evaporator compared to lacquer thinner that it may be a pain in the butt, leaving oily residue all over. If Lacquer thinner doesn't work on the silicone, then at worst you could use it to clean up the residue from the Xylene.

I'd also bet you won't need a retarder if you're using Xylene as a thinner. I can't imagine needing even slower evaporation than that on a catalyzed ink.

Emulsion problems would be a surprise to me too. Just start with a decent dual-cure.

i'd probably start with a screen mesh or 230 - 300 to start with.

[ZooCity]

Yep, 2 part, catalyzed.  Is there something else out there that will be durable on silicone and friendlier to cure? 

I don't have any issue hitting the 5 min at 305˚ since the pcs are so small we could run the belt at "1" and line them up but I really don't want to do the post cure which would require some type of oven/low temp kiln.  Maybe run them twice/thrice through the dryer instead if it's even needed. 

Thank for that reminder on catalysts, I forget that as nylobond is the only catalyzing agent we ever use and that's rare. 

[Inkworks]

It's sounds like you'll be printing plain old silicone, not really "ink" Depending on how quickly they cure, you may need to rack them at the end. The 2 part silicone I used cured completely in 5-6 hours. I don't know how much heat would have cut off that, and I doubt it's the same you'll be using. (I was using RTV664 with a lot of diluent to lower the finished durometer)

Do they say how long of cure it needs?

On the plus side, I'd bet you'll get great adhesion and durability as silicone on silicone usually works very well.

Do be aware of possible contamination with Platinum cure Silicones, check this site:

http://rawmaterialsuppliers.com/cgi-bin/p/awtp-product-category.cgi?d=raw-material-suppliers&pc=11972

[ZooCity]

Damn, inkworks thank you!  That explained a lot for me.  I get along better when I know what I'm working with on more of a ground level. 

We should be all good on the contam issue save for the natural rubber tape we use but I'll be sure to stick the small images away from the tape or use acrylic adhesive. 

From the mfg on curing:

The material will cure fully in 5 minutes at 302ºF, but for optimal adhesion curing (or post curing) for 30-60 minutes at 150 – 180ºC is recommended.

I think a 3x run through the dryer at temp ought to be fine.  Then rack out overnight before packing to ship.  I'm not going to setup an oven just for this, we don't have the floor space. 

[Inkworks]

You should be fine. If you've printed WB before, you can use it as a frame of reference since they both can dry in the screen.

Mix enough ink and thin a bit, don't over thin! I generally find thicker ink to be easier to work with than too thin...to a point...! I like to add enough ink to the screen to comfortably print, then as the Xylene evaporates and the ink gets thicker add more of thinned ink rather than trying to thin it out on-screen. If it just gets too think, remove the ink from the screen and mix in more thinner off-screen.