5 Layer Co Extrusion Blown Film Machine

Barrier films usually adopt multi-layer structures such as PE / Tie / EVOH / Tie / PE or PA / EVOH / PE.
Each material layer performs a specific function: PE provides flexibility and heat sealing performance, PA improves mechanical strength and puncture resistance, and EVOH offers excellent oxygen barrier properties. Before production, raw materials are dried and delivered to the extruders through an automatic feeding system.

Different materials are processed through separate extruders. Inside the extruder, the polymer is melted, plasticized, and homogenized by the rotating screw. The molten polymers are then combined through a co-extrusion feedblock or spiral mandrel die head, forming a stable multi-layer melt structure.

The molten material exits through a circular die head and is inflated with air to form a tubular film bubble. Process parameters such as blow-up ratio, extrusion output, and die temperature must be precisely controlled to ensure stable film forming.

The film bubble is cooled using a high-efficiency air ring system. Modern blown film lines may also integrate automatic thickness control systems and internal bubble cooling to improve film thickness uniformity and product stability.

After cooling, the bubble is flattened through a collapsing frame and pulled by the haul-off unit. The film is then wound into rolls with controlled tension, making it suitable for downstream processes such as printing, lamination, and bag making.