Barrier films are multi-layer films that have been designed to be impervious to gas migration and are often called gas barrier films. They are used for lamination and protective system applications. The small size of the pores in these films prevents penetration of liquid water, but the interconnected pore structure allows for transmission of water vapor.

Barrier films are durable and flexible, having excellent compatibility with variety of products. They extend the shelf life and improve the hygienic conditions for handling the packaged products. They eliminate expensive and often inadequate cleanup. They are easy to use and quick to install and remove.

Barrier Film Materials
In most cases, in the cross sections of barrier films, the inner is made up of polyethylene sealing layer, the outer layer is thin and the middle layer of the barrier is of microscopic thickness. It is to be noted that the composition of the barrier material is most important in determining its permeability and not its thickness. Metal foil or aluminum foil is the most effective gas barrier material, which is followed by transparent ceramic barriers. EVOH, sputtered aluminum, barrier nylon are transparent plastic barrier layers used in the food industry. Each specific barrier material has its own unique barrier properties.

Barrier Film Construction
All gas barrier films are made of multiple layers. The outer layer is a strong plastic with a high melting point, often made of polyester or polypropylene. The inner-middle layer is the gas barrier material. The bottom layer is a low-density polyethylene, which softens at relatively low temperatures. Additional inner layers are used to increase the barrier properties of the film, and adhesives may be used to cement the layers.

Commercially significant materials used for making barrier films are aluminum foils, glass-coated films, nylon resin, metallized film, cyclic olefin copolymer resin and films, polychlorotrifluoroethylene resins and films, polytetrafluoroethylene, diverse polyolefins, and precipitation-cast polyurethanes.

The number of layers, the selection of polymers, the layer configuration and the thickness of individual layers depend on the intended film use.

Barrier Films Applications
Barrier films are used for applications in protective clothing and packaging. These are also used as barrier against spills, as needed in carpet underlayments or baby seats. They offer excellent resistance to a wide variety of chemicals for chemical resistant clothing.

They are well suited in food packaging where moisture, oxygen and odor barrier is essential. It is ideal for applications such as cheese packaging, sausage chubs, and capliners. Some common examples for barrier films are found in grocery store. Bags used for packaging potato chips and meat products are gas barrier bags. They can also be laminated to other films and substrates for additional barrier functionality.

These films provide moisture protection in health care and pharmaceutical blister packaging and other industrial applications. They are also valued in exotic military, aerospace, aircraft, and electronic applications. Barrier films are used to make different packaging products like

• Packaging bags
• Aluminum foil
• Aluminum sheet
• Packaging pouch
• Packaging rolls