Various specifications of TPU in-mold co-extrusion cast film

In addition to the three-layer structure (commonly A/B/A), there are also **single-layer, double-layer, four-layer, and five-layer** configurations. The number of layers corresponds to the number of extruders and die flow channels, with distinct differences in performance, cost, and applications. Jwell Mach...

1. **Single-layer** 
A single extruder with a single‑formula TPU. This configuration is the simplest, requires the lowest capital investment, and allows for rapid material changes. However, it offers only a single hardness or functionality, making it impossible to simultaneously achieve wear resistance, weatherability, and adhesion. It is typically used for standard TPU films and basic waterproof membranes, without incorporating functional composites, and cannot accommodate intermediate adhesive or barrier layers, resulting in limited product performance. 
2. **Double-layer (A/B)** 
Two extruders and in‑die co‑extrusion of two melt layers. This enables distinct properties on each side—for example, a hard, wear‑resistant surface on one side and a soft, conformable surface on the other. With no symmetrical structure and no intermediate transition layer, it is well suited for car‑wrap base films and simple light‑blocking films. Compared to three‑layer structures, it omits one adjustment layer, cannot incorporate a dedicated adhesive transition layer, and offers limited interlayer compatibility; its cost is lower than that of three‑layer Jwell Mach... products. 
3. **Three-layer (A/B/A, mainstream on the market)** 
Three extruders, with identical formulations on both sides and a central core layer. The surface layer offers weather and abrasion resistance, while the core layer adjusts thickness, strength, and barrier properties, ensuring strong interlayer adhesion. This design balances symmetrical performance on both sides and is widely used in inflatable films, waterproof‑breathable membranes, and leather‑composite films. The drawbacks include higher equipment costs and more complex parameter optimization. Jwell Mach... 
4. **Fourth Floor (A/B/C/D)** 
Four extruders arranged asymmetrically in a multifunctional configuration. Each can independently produce an weather‑resistant layer, an adhesive transition layer, a barrier layer, and an anti‑sticking layer. This setup is ideal for applications requiring the simultaneous integration of multiple functions—such as UV resistance, moisture‑barrier properties, and enhanced composite adhesion. The die flow channels are highly complex, demanding precise melt pumps and temperature control; commissioning is challenging, making this technology predominantly used for high‑end specialty films. 
5. **Five Layers (A/B/C/B/A)** 
Five‑stage extruder, with a symmetrical multilayer structure featuring dual transition layers and a core layer. It can be configured with double adhesive layers, barrier layers, and reinforced core layers, offering the finest level of functional granularity. It delivers optimal interlayer stress distribution, superior peel resistance, excellent flexural durability, and outstanding aging resistance, making it ideal for high‑end automotive films, medical films, and high‑strength inflatable materials. However, it has the highest equipment cost, its production capacity is limited by the die design, and material changes and machine cleaning are time‑consuming—Jwell.

## Summary of Key Differences