Professional industrial inkjet printer manufactuers.
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Professional industrial inkjet printer manufactuers.
A common question we receive is whether a TIJ printer for plastic bags can print production dates, batch numbers, barcodes or QR codes directly onto plastic packaging.
In many applications, it can.
But the more useful question is not simply:
“Can the printer put ink on plastic?”
The mark also needs to remain readable after printing.
Plastic bags are often relatively smooth and non-porous compared with paper packaging. That means ink adhesion and drying deserve much more attention.
A code that looks clear immediately after printing is not enough if it can be rubbed away during the next production step.
“Plastic Bag” Is Still Too Broad
Plastic packaging can use different films, laminates, coatings and printed surface layers.
Two bags that look similar in a photograph may not behave exactly the same when ink is applied.
That is why we prefer to test the real material.
For plastic bag inkjet printing, the surface that actually receives the ink matters more than the general word “plastic.”
A pre-printed bag may have a coating or varnish in the coding area.
Another package may use a smooth film without the same surface treatment.
The ink result can change.
We therefore avoid promising the same adhesion on every plastic bag based only on appearance.
Drying Time Matters Because Production Does Not Stop After Printing
One of the easiest mistakes in a sample test is checking the code immediately after it leaves the printhead.
Production continues.
The bag may touch a roller.
It may move through a guide.
Another package may rub against it.
It may be stacked or handled shortly afterwards.
For an inkjet printer for plastic packaging, the useful question is:
Does the code remain acceptable after these normal production steps?
Fast-drying ink can be important on non-porous surfaces, but ink selection should still be based on the actual material.
The goal is not simply the shortest possible drying time.
The code also needs suitable adhesion, contrast and readability.
Print Position Can Be More Important Than Expected
If there is a choice, we normally look for a printing area that is flat, accessible and reasonably stable.
Printing onto a flexible bag after it has already become curved can make the application more difficult.
A flat area before final filling may be easier, depending on the packaging machine.
The printed area should also avoid immediate contact with rollers or guides when possible.
This can give the ink more time before the surface is touched.
For a thermal inkjet printer for plastic bags, physical installation and ink choice therefore need to be considered together.
Moving the printhead to a better position can sometimes solve a problem that would otherwise be blamed on the ink.
QR Codes Make Surface Problems Easier to See
A large date code can remain readable even if the dot edges are not perfect.
A small QR code has less tolerance.
On glossy plastic packaging, reflections can affect scanning. Wrinkles can distort the code. Poor adhesion can damage individual cells if the surface is touched too soon.
For QR code printing on plastic bags, we prefer to test the actual code size.
If the customer needs the code for product traceability, we scan it after printing.
If the bag will normally be filled when the customer scans it, it is also useful to consider what happens to the code after the package changes shape.
A perfectly flat laboratory sample does not always represent the final product.
TIJ Is Not Automatically Suitable for Every Plastic Surface
TIJ offers a practical way to print variable dates, batch numbers and machine-readable codes without preparing printing plates.
But we would not say that one cartridge or one ink can work equally well on every plastic package.
Some surfaces need a specific ink approach.
Some bags may need a different print location.
Some materials should be tested before the printer is selected.
This is especially important when adhesion is more important than simply making a visible mark.
For a new project, a small quantity of the real bag material and the customer's actual printing content normally gives us a much better basis for testing.
If the final requirement is a date code, we test the date code.
If the customer wants a small QR code, we test and scan that QR code.
For a TIJ printer for plastic bags, the result we care about is not the first second after printing.
It is whether the code remains usable during the customer's actual production and handling process.
Professional industrial inkjet printer manufactuers.
Industrial Inkjet Printer
