Multi-layer co extruded composite film

summary

Multi layer co extrusion blown composite film is commonly used as 2-3 layers of co extrusion film, and there are also 4 or 5 layers of composite film

Multi layer co extrusion casting composite film. Initially consisting of 2-3 layers, it has now developed to 5-7 layers. The equipment and technology for 5-layer co extrusion casting film have become more perfect and mature.

Multilayer co extruded composite films have the following advantages

1. Improve the quality of the film and endow it with special properties

Multi layer co extruded film can combine the advantages of various single materials, overcome the shortcomings of single materials, and obtain high-performance films, such as 5-layer co extruded film, LDPE/adhesive layer PA6/adhesive layer/LDPE. It combines the gas barrier properties of nylon film, water vapor barrier properties of LDPE film, good heat sealing properties, high mechanical properties, puncture resistance, and excellent low-temperature resistance of composite films.

2. Improve the post processing performance of thin films

The post-processing properties of thin films mainly include heat sealing bag making and adaptability to automatic packaging machinery.

1) Improve the heat sealing strength, reduce the heat sealing temperature, and use specialized resins such as LDPE and EVA with good heat sealing performance as co extruded inner layer materials to improve the heat sealing temperature, quality, and yield of composite film materials.

2) Prevent adhesion between the film and the heat sealing heating plate. Choosing LDPE resin or HDPE resin with low melt flow rate as the co extruded outer layer material can prevent adhesion between the film and the heating plate.

3) When packaging oily food or oil like items, in order to prevent oil pollution and reduce the heat sealing strength, ionic polymer resins with good heat sealing properties, oil resistance, and high heat sealing strength can be selected as the inner layer of the co extruded film, which can achieve both oil resistance and improved heat sealing strength.

4) Selecting rigid HDPE, MDPE, and PP resins as co extruded film surface materials can improve the rigidity and stiffness of composite films, suitable for automatic packaging machinery.

3. Can reduce film costs

1) It can produce extremely thin functional film layers, while the co extrusion method can produce extremely thin (such as 2um) film layers, which can economically and reasonably utilize materials and is difficult to achieve by other methods.

2) Functional additives such as Antistatic agent, colorant, smoothing agent or their masterbatch can be saved. It can be added to the surface resin according to the usage requirements, which greatly reduces the amount added compared to single-layer films, thereby reducing costs.

3) Recyclable materials can be used as intermediate layers and new materials as surface layers, which can effectively reduce costs. For example, PP/PP recycled materials/PP three-layer composite films can be used for packaging pastries and biscuits. Of course, recycled materials used for food packaging should be clean and hygienic recycled materials

4. Advantages of co extrusion composite compared to dry composite.

1) Co extrusion composite is a one-step production method with short cycle, high efficiency, and dry composite 5-layer films requiring 3-4 composite processing times, resulting in a long production cycle.

2) Dry lamination requires adhesives and solvents, which can cause pollution to humans and the atmosphere. Therefore, recycling is necessary. The adhesive layer of co extrusion lamination is a composite resin, which is generally non-toxic.

3) The co extruded composite film leftover material can be recycled, while the dry composite film leftover material cannot be recycled.