Polyamide ink resins for untreated HDPE: how Unimide US 77 changes the cost calculation
Most flexo and gravure ink chemistry assumes a corona-treated film. Unimide US 77 lets printers test untreated HDPE and LDPE without adding a surface-treatment step.
The default workflow for flexo or gravure on polyolefin films is surface treatment followed by ink. Corona, plasma and flame treatment raise surface energy enough for the ink to wet and adhere. The method works, but it adds capital cost and another process step that can drift out of calibration.
Unimide US 77 is a polyamide ink resin built around a different assumption: that the substrate may not be treated. It passes the tape test on untreated HDPE and LDPE.
Why it works
The chemistry is a dimer-fatty-acid polyamide with a balanced amine/acid profile that interacts with the polyolefin surface directly, without relying on the surface-energy lift that corona treatment provides. It's alcohol and co-solvent soluble, so it slots into standard flexo and gravure ink make-up.
What it doesn't fix
It doesn't change ink rheology, you still tune your viscosity around the press. It doesn't solve adhesion to oily or contaminated film, substrate cleanliness still matters. And it doesn't override the residual-solvent profile of your ink: that's still on your formulation.
Where the cost changes
US 77 changes the cost calculation when a converter is considering another corona line only to keep up with HDPE or LDPE printing demand. In those cases, reformulating around US 77 may avoid that investment.
Test before specifying
Send the film you are testing. We can provide a sample and a tape-test protocol before the grade is specified for production.