What is Multi-layer plastic film?

A mixture of several materials at the lowest cost is always used to achieve optimal packaging performance,therefore, plastic film is usually mixed with other plastic materials or other materials by coating, complex, and of coextrusion process.

1) Coating
A thin layer of plastic film commonly is coated on the surface of the other layer of plastics film or plastic sheet, or more generally, is applied to the non-plastic substrates such as paper, cellophane or aluminum foil. Can coated by a solution, suspension, or melt coated.The reason of give flexible packaging coating is coating can make paper, cellophane, aluminum foil more easily heat sealable; provide moisture resistant for
paper or cellophane; improve barrier properties; prevent the substrate in direct contact with the product.
Low density polyethylene is always coated on paper, this makes a heat sealing, moisture proof, protect the printing does not wear. It is also commonly used for aluminum foil, sealing and produce abrasion resistance, aluminum foil to prevent interaction with the product. PVDC copolymer coating is also used to improve the barrier properties and heat sealing.

2) Compound
Compound is the two kinds of the composite film substrate combined processes. In flexible packaging applications, it commonly uses plastic film combined with paper or foil, or paper and aluminum foil. There are a variety of complex methods used. When using plastic film as a substrate or layer of the final structure, the composite binder are generally low density polyethylene, to the composite by extrusion, the extrusion process is the compound. Flexible when there is paper in which the reason is often used because it has excellent printability, durability, strength and can produce. When using an aluminum foil, which is commonly used because it is light and permeate good barrier agent. Sometimes, in order to use it mainly obtain the desired appearance.
Another important application is the production of a composite material covered print. In this material, the first material is a negative printing, and then another substrate composite to a same or different polymer production. Printing can be seen through the transparent plastic to prevent wear and tear, so the appearance of the surface area more attractive bright printed updates.

3) Coextrusion
Co-extruded multi-layer film can be produced without the two steps:producing the first layer film, and then the two-layer film combined. The molten polymer is carefully added together, producing layered melt, and then in a conventional manner to produce a plastic film or sheet. Only when the plastic flexible packaging structure, in general, superior to composite coextrusion, unless a covering printing. But it is clear, can not use the non- co-extruded thermoplastic materials included.
Compared with the compound, the main advantage is the ability to use co-extruded thin layer of material capable of producing much thinner than a mono-layer film. This is particularly important for expensive substrates, as usual for imparting barrier properties of the material. The amount of expensive resins used
for produce the desired properties as long as it is sufficient. Thinness of the layer is not restricted by non-liner film production and processed in the subsequent process requirements of the composite.