Modern multilayer film is supposed to replace such materials as glass, metal, paper. Each polymer material has wide range of properties: physical, mechanical, barrier, optical.
Polyethylene (PE) Depending on the parameters of polymerization and catalysts used you can get polyethylene of different types, which considerably differ by their properties. The main properties of polyethylene are good heat sealability, barrier to steam.
Polyamid (PA) is the material with high tensile strength, transparent, has a barrier to oxygen, nitrogen, carbon dioxide. PA is not resistant to water vapor, it is absorbent.
Polyethylene terephthalate (PET) is characterized by high strength, is resistant to abrasion and multiple deformations during stretching and folding. It has low
absorbability and high transparency. The range of working temperatures is from -60°С to 170°С
In order to ensure full protection of product the multilayer structure is used. The technologies make it possible to produce films, consisting of 14:16 layers. Each layer has its own properties, which are not lost inside the multilayer structure, but they supplement each other.
Standard situation. It is necessary to protect the product from oxygen effect, water vapor and ensure high transparency.
This problem can be solved in two ways:
1. Coextruded film. PE / adhesive / PA. Polyethylene protects the product from the effects of water vapor and provides heat sealability. PA, in turn, protects packaging against oxygen.
2. . Laminated film. PE / adhesive / PET. Polyethylene protects the product from the effects of water vapor and provides heat sealability. Polyethylene packaging protects against oxygen. Interlayer printing in this structure is also possible, which makes the package more attractive, keeps high-gloss paint and protects against abrasion.
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As became clear from the description above the multilayer film can be produced by several means: coextrusion, lamination.
Coextrusion is the process of forming a product by a continuous or periodic punching of material in a plastic or viscous flow condition via the instrument (head).
Coextrusion can be divided into the flat coextrusion and coextrusion with blow. These two methods differ by the geometry of forming element.
So the coextrusion is the process of simultaneous extrusion of multiple materials through the forming holes to produce a multilayer film in one pass.
Lamination is the process of gluing of two or more materials. Lamination allows connection of materials, which are cannot be connected by means of extrusion. For example, PET and PE, Pet and PP, aluminium foil and PE etc.
To make the film fulfill its function it is necessary to make clear requirements for the future packaging. There is the number of factors, which influence the choice of the packaging type:
The type of the product, that will be packed.
Necessity of freezing.
Welding through pollution.
Molding depth (for thermoforming "low" films).
Wide range of additive can be placed into to the film:
- Peel – easy opening effect;
- Slip - is is intended for to reduce friction, i.e to improve the slip between the layers of the film during its processing.
- anti-block - is intended for to prevent self-adhesion of film layers in rolls, and easy opening of bag when placing the product.
- antistatic - is intended for to reduce the electrostatic charge on the surface of the film.
- anti-fog - is intended for to prevent dropwise condensation on the film surface.
- UV-filters - is intended for to stabilize and protect the film and the product, which is packed in it from UV rays.
- Antimicrobial additive - is intended for the active protection of the package from the development of mold, bacteria and germs.
Modern film packaging material is a product of high technology, which can provide a high level of protection for your products.