Film for clear-window packaging
A window is the one part of a printed pack that has to carry two jobs at once: show the product, and keep the barrier the rest of the structure was built for. A metal layer cannot do the first, so the window is where AlOx earns its place.
What the window has to do
The window is a hole in the print, so the film that fills it is the whole barrier of that area. Four properties decide whether it works.
| Property | Why it matters in a window | On the grade sheet |
|---|---|---|
| Transparency | The product has to be seen through the film, not guessed at | Haze ≤ 2 % · GB/T 2410 |
| Barrier | The window interrupts the print web, so it has to carry the OTR and WVTR itself | OTR · WVTR with conditions |
| Printability | Ink sits next to the window, and sometimes on the coated face itself | Wetting tension ≥ 38 mN/m |
| Lamination | A patch or a printed window is bonded into the structure | Adhesion confirmed in the trial |
Which grade to start from
A printable window starts from the printing grade; a window that is bonded inside a laminate uses the lamination grade. Both stay clear.
- ALOX BOPP-A printing grade
- 18 µm OTR ≤ 1, typ. 0.63 · WVTR ≤ 1, typ. 0.89
- ALOX BOPP-B lamination grade
- 18 µm OTR ≤ 2, typ. 1.29 · WVTR ≤ 2, typ. 1.32
- Haze both grades
- ≤ 2 % typ. 1.59 (A) / 1.39 (B) · GB/T 2410
- High-barrier window ALOX PET
- 12.0–12.5 µm OTR typ. 0.11–1.55
Printing grade or lamination grade
A carries a protective coating over the AlOx layer and is specified for printing as well as lamination: it is the grade to take when the ink runs over or beside the window. B has no protective coat and is specified for lamination only, which is what a window patch bonded into a board or film structure usually needs.
A is also specified tighter on barrier: OTR ≤ 1 and WVTR ≤ 1 against ≤ 2 for B.
Why not a metallized film
A metallized layer is the better light barrier, and the reason a metalized pack hides the product. If the brief is a visible product, the window has to come from an oxide layer; the two choices are exclusive in the same web.
What the trial has to prove
Adhesion at the window edge, haze after lamination or patch application, and the OTR of the finished structure rather than of the film alone. A window is a bond as much as a barrier.
Structures converters run
Starting points, quoted against the converting process you actually run. The trial decides the gauge and the bond.
| Pack | Typical structure | Grade in the structure | What it buys |
|---|---|---|---|
| Printed PP pack with a window | PP / AlOx-BOPP / PP | ALOX BOPP-A | Clear barrier with the product visible through the print |
| Board pack with a film window | board / AlOx-BOPP patch | ALOX BOPP-B | Window film bonded into a board structure |
| Flat high-barrier window | PET / AlOx-PET / PE | ALOX PET | Transparent barrier where the process rules out BOPP |
Other application notes: coffee packaging · snacks and confectionery · dry pet food · documentation and samples.
Questions before the trial
If the answer you need is not here, ask it directly — technical questions get an engineer's reply, not a brochure.
Does the window stay clear?
Yes. AlOx is an oxide layer, not a metal layer, and the haze limit on both grades is 2 % or below — typical 1.59 on grade A and 1.39 on grade B, to GB/T 2410.
Can the film be printed?
Grade A can: it carries a protective coating over the oxide and its AlOx face is specified at ≥ 38 mN/m wetting tension, running at 48 typical. That is the surface a press needs when the ink sits beside or over the window.
Does the window lose the barrier of the pack?
Not from the film: the window film carries its own OTR and WVTR, so it is a barrier area rather than a hole. The edge bond is the part the trial has to confirm.
Can I get a metallized window?
A metallized film is not transparent, so it cannot serve as a visible window. It is the right choice when light barrier matters more than visibility, and that is a different pack.
What is the minimum order?
One roll of ALOX film. A4 sheets are free, and a sample roll ships with its dimension sheet and lot data.
Trial a window structure
Tell us the structure the window goes into, the width and the print face. The sample roll ships with its lot data, and the edge-bond result goes on the grade record.
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