5-Layer Co-Extrusion Blown Film Machine

A 3-layer machine produces film where all three layers are made from compatible materials — typically PE-family resins that bond to each other without adhesives. A 5-layer machine introduces a barrier core material (EVOH or PA) that is chemically incompatible with PE. Two additional TIE (adhesive) layers are required — one on each side of the barrier core — to bond the structure together. The result is a film that can block oxygen transmission or resist puncture at a level that PE alone cannot achieve. The trade-off is higher material cost, greater process complexity, and the need for five independent extruders and a 5-channel die head.

EVOH (ethylene vinyl alcohol) is selected primarily for its oxygen barrier performance. It is the standard choice for food packaging applications where extending shelf life by blocking oxygen transmission is the primary requirement — vacuum bags, retort pouches, MAP film and dairy packaging are typical examples.

PA (polyamide / nylon) is selected primarily for mechanical performance — puncture resistance, abrasion resistance and tensile strength. It is the standard choice for heavy-duty industrial packaging where the film must withstand rough handling, sharp edges or heavy loads. Chemical bags, fertilizer packaging and industrial liner bags are typical examples.

The two materials are not interchangeable — they serve different performance requirements. LayerQuestar's 5-layer line supports both configurations. If your application requires both oxygen barrier and puncture resistance simultaneously, contact us to discuss 7-layer structures that can combine both functions.

A TIE layer is a thin adhesive resin layer — typically maleic anhydride grafted polyethylene — that creates a chemical bond between two otherwise incompatible materials. PE and EVOH will not bond to each other directly; without a TIE layer between them, the film structure would delaminate under mechanical stress or during heat sealing.

In a 5-layer PE/TIE/EVOH/TIE/PE structure, two TIE layers are used — one between the outer PE and the EVOH core, and one between the EVOH core and the inner PE. This symmetric arrangement ensures the barrier core is fully bonded on both sides, creating a stable, delamination-resistant film. The TIE layer is typically very thin (5–10% of total film thickness) but is essential to the structural integrity of the film.

Technically yes — a 5-layer machine can run PE-only structures by feeding compatible PE-family resins into all five extruders. However, this is not an economically rational use of the machine. A 5-layer co-extrusion line carries significantly higher capital cost, operating complexity and maintenance requirements than a 3-layer machine. Running it on standard PE film means paying for capability you are not using.

If your current and foreseeable product range does not require EVOH or PA barrier layers, a 3-layer ABA or ABC machine is the more appropriate investment. Contact LayerQuestar and we will recommend the configuration that matches your actual production requirements.

Yes. EVOH has a narrower processing window than PE and is sensitive to both under-heating and over-heating. Processing temperatures typically range from 190°C to 230°C depending on the specific EVOH grade and ethylene content — lower ethylene content grades generally require higher processing temperatures. EVOH is also sensitive to moisture: it must be pre-dried before processing (typically at 80°C for 4–6 hours) and should be protected from ambient humidity during storage and feeding.

Critically, EVOH degrades if left in the barrel at processing temperature without material flow. If production is interrupted, the EVOH extruder must be purged promptly. LayerQuestar's OMRON PID temperature control system — with ±1°C deviation under stable conditions — is specified in part to meet the precise temperature management requirements of EVOH processing.

The centre extruder (C) feeds the EVOH or PA barrier core layer, which is intentionally kept thin — typically 5–15% of total film thickness. EVOH and PA are significantly more expensive than PE, so minimising their proportion while maintaining barrier performance is a key part of the film cost structure. A smaller screw diameter on Extruder C is correctly matched to this lower output requirement.

The outer PE layers (Extruders A and E) carry the majority of the film's total thickness and require higher output capacity — hence the larger screw diameters. This asymmetric extruder sizing is standard practice in 5-layer barrier film line design and is reflected in LayerQuestar's model specifications.

Yes. Each extruder's screw speed is independently controlled via its variable-frequency drive. Adjusting the screw speed of any individual extruder changes that layer's output rate and therefore its proportion of the total film thickness. This can be done while the line is running without stopping production.

In practice, operators adjust layer ratios in response to changes in raw material costs, customer specification requirements, or film performance targets. The EVOH or PA core layer ratio is typically the most actively managed — increasing it improves barrier performance but raises material cost, while reducing it lowers cost but may reduce barrier performance below specification.

Under normal production conditions, a 5-layer co-extrusion line typically requires 2–3 operators per shift. A lead operator manages the five extruder control panels, die head and process parameters. A second operator handles winding, roll changes and film quality monitoring. A third operator — optional depending on line size and production pace — manages material feeding across the five hoppers and assists with roll handling.

Prior experience with multi-layer extrusion is recommended for the lead operator role, particularly for EVOH processing where temperature management and purging protocols are critical. LayerQuestar provides operator training as part of the commissioning process and remote training support is available after installation.