Yes. Bird eye fabric can be bonded with TPU film, but the result depends heavily on the hole size and actual yarn contact area.
For this type of fabric, the main challenge is not whether the TPU can stick to polyester or other fibers. The real issue is that bird eye fabric contains open spaces where there is no yarn surface available for bonding.
As the openings become larger, two things happen at the same time:
- the effective bonding area decreases;
- the risk of adhesive or molten material penetrating through the openings increases.
This is why an open bird eye structure usually requires more careful lamination development than a flat knitted fabric.
Hole Size Directly Affects Bonding Quality
In our development experience, hole size is one of the first specifications we check before selecting the lamination process.
The principle is simple:
Larger holes → less yarn contact area → lower effective bonding area
TPU film or adhesive can only bond to the yarns surrounding the openings. It cannot create textile contact inside an empty hole.
This means the peel-strength limit is sometimes determined less by the adhesive itself and more by how much actual fabric surface is available.
In our experience, once the openings approach roughly 1–2 mm, the bonding behavior normally needs more attention.
This is not a universal technical limit. Yarn density, GSM, fabric construction, TPU film and processing conditions all affect the final result. However, it is a useful warning point during development.
| Bird Eye Structure | Bonding Area | Penetration Risk | Development Difficulty |
|---|---|---|---|
| Small, dense holes | Higher | Lower | Relatively easy |
| Medium holes | Moderate | Moderate | Process adjustment needed |
| Large, open holes | Lower | Higher | Trial strongly recommended |
Three Problems We Watch Most Closely
Adhesive Strike-Through
Large openings provide more space for molten adhesive to flow into the fabric.
When temperature, pressure or adhesive flow is too high, the front surface may show:
- glue dots;
- shiny spots;
- tacky areas;
- visible bonding marks.
This is why increasing adhesive quantity is not always the correct solution when peel strength is low.
If there is not enough yarn contact area, additional adhesive may simply move into the holes instead of creating useful bonding.
For relatively open bird eye structures, we generally prefer a controlled adhesive film system over a highly mobile liquid adhesive.
For very open constructions, additional surface stabilization or pre-treatment may also be considered before lamination.
Low Peel Strength Around the Openings
Another common problem is local delamination.
On a relatively flat fabric, the bonding interface is more continuous. With bird eye fabric, the structure is different:
yarn → hole → yarn → hole
Part of the TPU layer is therefore positioned above an area without direct fabric contact.
When the laminated fabric is bent, stretched or peeled, stress can become concentrated around the edges of the holes.
This means a peel-strength problem may begin locally around the bird eye openings rather than appearing evenly across the whole surface.
When this happens, we normally check:
- hole size;
- yarn density;
- actual bonding area;
- adhesive distribution;
- TPU flexibility.
Simply changing to a “stronger adhesive” may not solve a structural bonding problem.
Wrinkling and Curling
A laminate can have acceptable peel strength and still fail in practical use.
One reason is a mismatch between the TPU film and the thermal or elastic behavior of the bird eye fabric.
During lamination and cooling, the fabric and TPU may shrink or recover at different rates.
Possible results include:
- surface wrinkles;
- edge curling;
- dimensional instability;
- distortion after relaxation.
This becomes especially important when the bird eye fabric contains spandex or has noticeable stretch.
The fabric, adhesive and TPU membrane must work as one structure after bonding. If their stretch or thermal behavior is very different, the laminate may become unstable even if the initial bonding looks good.
Temperature and Pressure Need to Be Balanced
Bird eye lamination usually has a narrower processing window than a flat fabric.
If the temperature or pressure is too low:
- bonding may be incomplete;
- peel strength may be insufficient.
If it is too high:
- the adhesive may become too mobile;
- penetration through the holes may increase;
- the surface may develop shiny marks;
- the hand feel may become harder;
- the knitted structure may deform.
The objective is therefore not maximum heat or maximum pressure.
It is:
enough bonding between the adhesive and yarn surface without excessive flow into the openings.
This is why we prefer trial development using the actual bird eye fabric and TPU construction rather than copying a lamination setting from another fabric.
What Happens to Breathability?
This is another point that should be clarified before development.
Bird eye fabric is naturally open and allows direct airflow through the knitted holes.
Once a continuous TPU membrane is laminated over the structure, those holes are covered.
The finished laminate may still provide moisture-vapor transmission if a breathable membrane is selected, but this is different from the original air permeability of the bird eye fabric.
So when a customer asks for a “breathable bird eye + TPU laminate,” we normally clarify whether they mean:
- direct airflow;
- moisture-vapor transmission;
- wearing comfort;
- waterproof but moisture-permeable performance.
If maximum airflow is the main requirement, covering the bird eye structure with a continuous membrane may work against the original purpose of using an open knit.
What We Check During the First Trial
Before moving to bulk production, we first check the laminate itself.
| Check | What We Look For |
|---|---|
| Surface | Glue dots, shiny spots, strike-through, wrinkles |
| Bonding | Uneven peel or separation around holes |
| Stretch | Whether TPU follows the fabric without separation |
| Relaxation | Curling or dimensional distortion after cooling |
| Performance | Peel strength, waterproofness, MVTR and wash durability |
For open bird eye structures, we prefer solving visible structural problems first before optimizing laboratory performance.
So, Is Your Bird Eye Fabric Suitable for TPU Lamination?
Usually, yes—but hole size can matter more than the basic fiber composition.
A smaller, denser bird eye structure normally provides a larger bonding area and a wider processing window.
As the openings become larger, three risks increase together:
less bonding area + higher penetration risk + greater stress concentration around the holes
For bird eye fabrics with visibly open structures, especially those approaching the 1–2 mm opening range in our development experience, we recommend a lamination trial before confirming bulk production.
Before development, the most useful information is:
- bird eye hole size;
- GSM;
- composition;
- stretch requirement;
- TPU film specification;
- waterproof or MVTR target;
- final application.
For this type of laminated fabric, choosing a suitable fabric structure + adhesive system + TPU film is more important than simply selecting the strongest adhesive.