คู่มือการเลือกสายการผลิตฟิล์มหลายชั้นแบบอัดรีด: 3, 5, 7, 9 หรือ 11 ชั้น?

More layers can provide more freedom to distribute sealant, structural, barrier, tie and recycled materials, but every added extruder and flow channel increases capital cost, control complexity, cleaning time and operator skill requirements. The most advanced line is not automatically the most profitable one.

This guide focuses on blown-film coextrusion for flexible packaging. It explains what layer count changes, where each configuration fits and how to select a line from the performance of the finished package backward.

First Define What the Film Must Do

Before choosing three, five or eleven layers, create a film specification that includes:

• Finished-film width and thickness range
• Target output in kg/h and line speed
• Oxygen and water-vapor transmission requirements
• Seal initiation temperature, hot tack and seal strength
• Puncture, dart impact, tensile and tear performance
• Transparency, haze, gloss and print surface
• Retort, pasteurization, freezing or sterilization exposure
• Food-contact or other regulatory requirements
• Converting method, including printing, lamination, bag making and thermoforming
• Recyclability goals and permitted rework content

Layer count is a means of meeting these requirements. It is not itself a quality specification.

What Each Layer Does

Common multilayer film functions include:

• Seal layer: contacts the package interior and provides the required sealing window, contamination resistance or peel behavior.
• Structural layer: supplies stiffness, toughness, puncture resistance and machinability; polyethylene families are widely used.
• Barrier layer: materials such as EVOH can limit oxygen transmission, while polyamide can add toughness and barrier performance. Actual barrier depends on grade, thickness, humidity and orientation.
• Tie layer: an adhesive resin bonds otherwise incompatible polymers, such as PE and EVOH or PA.
• Outer/print layer: supports printing, surface treatment, optical properties and abuse resistance.
• Rework layer: uses compatible in-house edge trim or start-up scrap without placing it on the food-contact or print surface, subject to regulation and performance validation.

One polymer may appear in several layers, and one extruder can sometimes feed more than one symmetrical layer through the die. Therefore, “seven layers” does not necessarily mean seven different resins or seven extruders. Ask the machine supplier for the exact extruder-to-layer mapping and minimum controllable layer percentage.

3-Layer Film: Efficient for Mainstream Structures

Typical arrangements are A/B/A or A/B/C. Three-layer lines suit general packaging, liners, lamination film, shrink film and other products that need differentiated surfaces or a strong core but not a complex high-barrier structure.

With A/B/A, a manufacturer can use premium resin on both surfaces and a lower-cost or rework-containing formulation in the core. A/B/C permits different print and seal sides. Three-layer equipment has fewer extruders, simpler controls, faster cleaning and generally lower investment than higher-layer systems.

Choose three layers when a validated structure meets all package requirements and the product portfolio is stable. Do not choose it when future products will clearly require a barrier core isolated by tie layers.

5-Layer Film: A Practical Step Into Barrier Packaging

A five-layer structure such as PE/tie/EVOH/tie/PE can place a thin oxygen-barrier layer between protective and sealable polyolefin layers. Five layers are also useful for assigning different mechanical or sealing functions without moving to a highly complex die.

For many food and non-food barrier applications, five layers provide a good balance of performance, investment and operating simplicity. The limitation is allocation freedom: once two tie layers and one barrier layer are assigned, only two layers remain for the outside and inside functions. If the film needs separate print, toughness, recycled-content and specialty-seal layers, five may be restrictive.

เจเวลล์ 3/5-layer classical blown film extrusion line processes common polyethylene families as well as PA, EVOH and tie materials in suitable configurations, with listed models covering different widths and outputs.

7-Layer Film: More Control Over Cost and Performance

Seven layers allow a barrier structure to be supplemented with dedicated bulk, abuse or seal layers. A conceptual structure might be outer PE/structural PE/tie/EVOH/tie/tough PE/seal PE. The actual resins and ratios must be engineered for the application.

This additional freedom can reduce the percentage of expensive functional resin while maintaining performance, improve curl balance and support differentiated inside and outside surfaces. Seven-layer lines are widely relevant to demanding food packaging, vacuum bags and structures using PA or EVOH.

Choose seven layers when the product portfolio needs high barrier plus meaningful formulation flexibility, and when the expected volume can absorb higher capital and training costs.

9-Layer Film: Fine Layer Allocation and Broader Product Range

Nine-layer systems can split structural or functional materials into thinner layers, add a dedicated rework position, or build more sophisticated symmetrical and asymmetrical structures. This can improve downgauging options and let a converter serve several high-value packaging categories on one platform.

The business case depends on whether customers pay for that flexibility. Thin functional layers require accurate gravimetric feeding, stable low-output extruders, precise temperature control and a die capable of uniform distribution. A nominal nine-layer line that cannot hold a low barrier-layer ratio will waste expensive resin.

Changeovers also deserve attention. More material circuits mean more resin retained in extruders, adapters and die channels. Frequent shifts between incompatible materials may reduce effective uptime.

11-Layer Film: Maximum Architecture, Maximum Discipline

Eleven-layer equipment is intended for complex, high-performance structures and converters that need very fine allocation of multiple functions. It can create room for separate seal, bulk, toughness, tie, barrier, rework and outer layers, sometimes with symmetrical repetition to control stress and curl.

The benefits include material optimization and product differentiation. The costs include more drives, feeders, heating zones, maintenance points and process interactions. Recipe development and troubleshooting also become more demanding.

An eleven-layer line is justified when a defined product roadmap and customer demand require it—not merely because competitors advertise more layers. JWELL’s 7/9/11-layer high-barrier blown film line is designed for PA- and EVOH-containing structures and lists automatic air-ring, online thickness-control and optional internal-bubble-cooling capabilities.

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Machine Specifications That Matter More Than Layer Count

Extruder sizing and minimum output

Each extruder should operate in a stable range at the smallest and largest required layer ratios. Check screw design for every resin family, drive torque, cooling and residence time. A tiny EVOH layer cannot be controlled well by an oversized extruder operating below its stable range.

Die and flow-path design

Ask how the supplier models flow, balances layers around the circumference and manages polymers with different viscosities. Confirm acceptable melt-temperature differences and how the design limits interfacial instability.

Feeding and thickness control

Loss-in-weight feeding supports repeatable layer ratios. An automatic air ring and online gauge can close the loop on thickness profile. Verify measurement method, correction speed and what happens during sensor failure.

Bubble cooling and stability

Internal bubble cooling can raise cooling capacity and improve bubble control, but it must be integrated with air-ring, cage and haul-off design. Define frost-line stability, width control and achievable output on your formulation.

Winding and downstream compatibility

Poor winding can erase the value created upstream. Specify roll diameter, tension range, taper-tension control, slit configuration, automatic changeover and surface/center winding needs. Confirm compatibility with printing and bag-making equipment.

Build the Financial Case

Compare total cost per saleable kilogram and per package. Validate projected resin savings with trials, and include power, labor, scrap, purging resin, downtime and spare parts.

During the factory acceptance test, run at least one demanding structure using the intended resin grades. Measure output, thickness profile, layer distribution, optical and mechanical properties, barrier performance, roll quality, scrap and energy consumption. A clear test protocol is more valuable than a generic maximum-output claim.

Choose the Layer Count From the Package Backward

The correct multilayer film extrusion line is the least complex configuration that meets today’s validated specifications while leaving commercially justified room for future products. Bring JWELL your target structures, resin grades, layer ratios, barrier targets, width, thickness, output and converting requirements. Explore the complete film extrusion line portfolio or contact JWELL’s film team for a layer map, equipment configuration and trial plan.