Multi-Layer Co-Extrusion Blow Molding Technology

2025-11-08

Multi-layer co-extrusion blow molding technology is an advanced plastic processing and molding method. A multi-layer blow molding machine connects two or more extruders to a co-extrusion die, allowing various plastic melts with different properties to converge in the die to form a multi-layered preform. This preform is then blown into shape using traditional blow molding processes (closing the mold and injecting compressed air), ultimately resulting in a multi-layered composite hollow plastic product.

Multi-Layer Co-Extrusion Blow Molding Technology-Kingplas Machinery Co., Ltd

Multi-Layer Co-Extrusion Blow Molding Technology Main Stages:

1. Co-extrusion Stage:

Different plastic particles (such as PP, PE, PA, EVOH, etc.) are fed into different extruders.

Each extruder, under precise temperature and pressure control, melts, plasticizes, and homogenizes the plastic.

This molten plastic flow is then conveyed into a specially designed co-extrusion die.

2. Multilayer Parison Formation Stage:

Inside the co-extrusion die, layers of melt are stacked and compounded according to a pre-defined structure (such as symmetrical or asymmetrical distribution).

The die design is crucial; it must ensure that each layer of melt flows smoothly and uniformly, and adheres well at the interfaces to prevent interlayer separation.

At the die exit, a tubular parison with a clearly defined layered structure is extruded continuously or intermittently.

3. Blow Molding Machine and Cooling Stage:

The die closes rapidly, clamping the parison.

Compressed air is injected into the parison through an air needle, causing it to adhere tightly to the cold inner wall of the die, forming the desired shape.

After the product cools and solidifies in the mold, it is removed from the mold and then trimmed and processed.

Advantages of Multi-Layer Blow Molding Machines:

1. Functionality: By combining the advantages of different materials, performance unattainable by a single material can be achieved. For example: strength + barrier properties + chemical resistance.

2. High-Performance Barrier Properties: This is the most prominent advantage of this technology. It can effectively extend the shelf life of food and pharmaceuticals.

3. Cost Savings: Inexpensive resins can be used as the main layer, requiring only a small amount of expensive barrier material, reducing costs while maintaining performance.

4. Lightweight Design: While achieving the same or better performance, multi-layer structures can be designed to be thinner, achieving lightweight design and saving materials.

5. Design Flexibility: Blow molding machines can flexibly adjust the number of layers and the thickness of each layer to adapt to different product requirements.

Why Choose Kingplas Machinery?

Has 30 years blow molding experience. Our blow molding machine portfolio is designed to handle a wide range of thermoplastic materials, including HDPE, PP, PE, PVC, PC, and PETG, for containers ranging from 10ml to 1250L.

Automatic Extrusion Blow Molding Machines: High-speed continuous extrusion systems (Single/Double Station) for cosmetics, lubricants, and household chemicals.
Accumulator Head Blow Molding Machine: Robust solutions for large-scale industrial parts, such as 200L drums, IBC tanks, and automotive components.
Multi-Layer Co-Extrusion Technology: Advanced 2-to-6 layer systems that provide superior barrier properties for agrochemical and fuel tank applications.
Turnkey Solutions: Integrated production lines including precision mold design and auxiliary equipment.