Packaging materials for Foods
Lamination (bonding together) of two or more films improves the appearance, barrier properties
or mechanical strength of a package. Some examples of laminated films are shown in Table 2.
Table 2: Selected laminated films used for food packaging
Typical food applications
Polyvinylidene chloride coated polypropylene Crisps, snackfoods, confectionery, ice cream,
Polyvinylidene chloride coated polypropylene- Bakery products, cheeses, confectionery,
dried fruit, frozen vegetables
Pies, crusty bread, bacon, coffee, cooked
Coffee, dried milk
Dried soup, dried vegetables, chocolate
Coextrusion is the simultaneous extrusion of two or more layers of different polymers to make a
film. Coextruded films have three main advantages over other types of film: they have very high
barrier properties, similar to laminates but produced at a lower cost; they are thinner than
laminates and are therefore easier to use on filling equipment; and the layers do not separate.
There are three main groups of polymers that are coextruded:
Low-density and high-density polyethylene, and polypropylene.
Polystyrene and acrylonitrile-butadiene-styrene.
Typically a three-layer coextrusion has an outside layer that has a high gloss and printability, a
middle bulk layer which provides stiffness and strength, and an inner layer which is suitable for
heat sealing. They are used, for example, for confectionery, snackfoods, cereals and dried foods.
Thicker coextrusions (75 - 3000 m) are formed into pots, tubs or trays (Table 3).
Table 3: Selected applications of coextruded plastic films
High impact polystyrene-PET
Polystyrene- polystyrene-PvDC- polystyrene
Typical food applications
Margarine, butter tubs
Juice and milk bottles
Tubs for butter, cheese, margarine,
bottles for coffee, mayonnaise, sauces.
Rigid and semi-rigid plastic containers
There is a wide range of plastic bottles, pots, jars, trays and tubs made from single or coextruded
plastics that are increasingly used for processed foods, when they are available in developing
countries. The main advantages, compared with glass and metal, are as follows:
Lower weight, resulting in savings of up to 40% in transport and distribution costs. Cups,
tubs and trays are tapered (a wider rim than base) for more compact stacking for transport
Lower production costs using less energy.
Tough, unbreakable and easy to seal.
Very good barrier properties.
Precisely moulded into a wider range of shapes than glass or metal containers.
Can be coloured for consumer appeal and to give UV-light protection to foods. However,
they are not re-usable, are less rigid than glass or metal for stacking and cannot be heated
to the same high temperatures as glass and metal. They are used for example as:
Cups or tubs for margarine, processed meats, cheese, spreads, yoghurt, peanut butter, dried
foods or ice cream and desserts (high-nitrile resin copolymers or high-impact polystyrene
and acrylonitrile butadiene styrene).
Trays for meat products and chocolates, tubs for margarine or jams, and (polyvinyl chloride)
- good oil resistance and low gas permeability.