The three-layer co extrusion blown film machine is an advanced plastic film production equipment widely used in packaging, agriculture, construction and other fields. Its core technology lies in the three-layer co extrusion process, which combines plastic melts of different materials or colors in a mold and finally blows them into multi-layer films.

Working principle

The working principle of a three-layer co extrusion blown film machine is based on co extrusion technology, which involves simultaneously extruding plastic melts of different materials or colors through multiple extruders and compounding them in a mold. The specific process is as follows:

Raw material preparation: Add different types of plastic particles into the hoppers of three extruders. Common plastic materials include polyethylene (PE), polypropylene (PP), polyester (PET), etc.

Melt extrusion: Each extruder heats plastic particles to a molten state and pushes the melt into the co extrusion mold through a screw. The temperature and pressure of the extruder need to be precisely controlled to ensure the uniformity and stability of the melt.

Co extrusion composite: In a co extrusion mold, the melt from three extruders is combined inside the mold to form a three-layer structure. The design of the mold determines the thickness of the film and the interlayer bonding strength.

Blow molding: The composite melt is extruded through the annular mouth of the mold to form a tubular thin film. Subsequently, the film is inflated to the desired diameter using an inflation device and rapidly cooled and shaped using a cooling device.

Roll cutting: The formed film is stretched by a traction device and finally rolled into a roll by a winding device. According to the needs, the film can undergo subsequent processing such as cutting and printing.

Structural composition

The three-layer co extrusion blown film machine mainly consists of the following parts:

Extruder: Typically equipped with three extruders, each used to extrude plastic melts of different materials or colors. The screw design, heating system, and control system of the extruder are key components.

Co extrusion mold: The mold design is complex, and it is necessary to ensure that the three-layer melt is uniformly compounded inside the mold. The flow channel design, temperature control, and pressure balance of the mold are important factors affecting the quality of the film.

Inflation device: including inflation ring, air ring, and cooling device. The inflation ring is used to inflate the film to the desired diameter, while the air ring and cooling device are used for rapid cooling and shaping.

Traction device: used for stretching film, controlling the thickness and width of the film. The speed and tension of the traction device need to be precisely controlled.

Rolling device: used to roll the film into a roll. The design of the winding device needs to ensure the flatness and winding tension of the film.

Control system: including temperature control, pressure control, speed control, etc. Modern three-layer co extrusion blown film machines are usually equipped with PLC control systems to achieve automated production.

Technical advantages

The three-layer co extrusion blown film machine has the following technical advantages compared to the single-layer blown film machine:

Multifunctionality: Through co extrusion technology, multi-layer films with different properties can be produced, such as high barrier properties, high strength, high transparency, etc.

Material saving: By designing the film structure reasonably, it is possible to reduce material usage and lower production costs while meeting performance requirements.

Stable quality: Co extrusion technology ensures high bonding strength between the layers of the film, and stable physical and chemical properties of the film.

High production efficiency: The three-layer co extrusion blown film machine can achieve continuous production with high production efficiency, suitable for large-scale production.

application area 

The thin films produced by the three-layer co extrusion blown film machine are widely used in the following fields:

Packaging industry: used for producing food packaging film, pharmaceutical packaging film, industrial packaging film, etc. Multilayer films have advantages such as high barrier properties, heat resistance, and chemical resistance.

In the agricultural field, it is used to produce agricultural films such as plastic film, greenhouse film, etc. The multilayer film has the properties of anti ultraviolet, anti-aging, heat preservation, etc.

Construction industry: used for producing thin films for construction, such as waterproof films, soundproof films, etc. Multilayer films have advantages such as high strength and weather resistance.

Other fields, such as the electronics industry, medical industry, etc., are used to produce films with special properties.

As an advanced plastic film production equipment, the three-layer co extrusion blown film machine achieves multifunctional, high-quality, and high-efficiency production through co extrusion technology. It is widely used in packaging, agriculture, construction and other fields, meeting the diverse needs of different industries for film performance. With the continuous advancement of technology, three-layer co extrusion blown film machines will play a greater role in promoting the development of the plastic film industry in the future.