Does anyone have any experience printing on polypropylene bags? They melt up in the dryer, and we think we might have found the ideal setting with the flash unit, but it's a dangerous middle ground between melting a bag and not curing the ink at all.
The ink seems to be bonding alright - these are for resuable grocery bags, so it's not like they'll be washed much (I think). If anyone has had any experience with something like this, any advice would be well appreciated.
thanks in advance!
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I just printed on a bunch of those bags and we experienced the melting problem at first also.
What we did was increase the belt speed to get it through faster, with just enough time to get to just at 250. We went from a speed setting of 2 to about 5 or 6.
just triple your belt speed and use a laser thermometer at the exit of the dryer and the finger touch test. slow the belt time bit by bit until you reach the perfect cure time. then go with that for the run.
this worked with me and should be more reliable and controllable than trying to do it with a flash unit.
What ink did you use? i would have just used marabu TPR, as its an air dry ink works on polypropylene with the help of some P2 primer, then no heat needed.
I haven't tried using it myself, but I know my supplier sells a polypropylene ink marketed specifically for printing on those bags. Something like that may make the job a lot easier.
Hi, I just got a job to print on 100% polypropylene thermals. They're from Militarythermals.com. Do I need a special ink and will they melt in the dryer? I know I can go water based but that presents other issues.
i just printed some frog toggs, and they are polypro. The supplier i used said to use the cp inks same as you would use on coroplast signs, and let them air dry. We printed a dozen or so of these frog toggs and they came out fine. It is just that you cannot do light print on dark cause the color will peek thru.
I have done several test on these bags now as these bags are so hot. Using a heat press, I have found 320 degrees for 4 seconds with jpss (dark-opaque) will work. If you use jpss light it is not enough heat and time to keep the transfer on the fabric. I put a mouse pad under the area and center it on the bag, there is some melting of the material that will give it a slight gloss over. By doing this I eliminate this effect on the reverse side and it will give the graphic a "framed look" since it does give it a gloss look. I also put parchment over the top. I'm still looking into other graphics I would think a plastisol will work since it is a short time for adhesion. I haven't tried this method yet. Hope this can help someone. OH I used inkjet pigment ink on to the transfer.
printing on polypropylene? 
