Polyamide is widely used for the production of flexible film for packaging of perishable food due to its unique combination of properties:
*Mechanical strength
*High heat distortion temperature
*High flexibility and toughness
*Good barrier to oxygen, chemicals and aroma substances
*High transparency
*Thermoformability
Polyamide provides excellent gas, flavor and aroma barrier properties, as well as high mechanical and excellent thermoforming functionalities.
The most common, synthetic polyamide is nylon, which is well known for its tensile strength and is used for preparing sutures, balloons (angiography), and catheters.
Polyamide is used in both cast and blown film equipment, predominantly for multilayer films. Since nylon is a semicrystalline material, processes that rapidly cool the polyamide film will result in lower crystallinity and therefore provide more transparent, flexible, thermoformable film.
Different types of polyamides are characterized by a number that relates to the number of carbons in the originating monomer. For example, nylon‐6 has 6 carbons and is typically used in packaging. Major polyamides for packaging materials are polyamide 6 and polyamide 66. Both polymers are semicrystalline and known for hardness.
For some applications such as shrink bags or sausage casing, a controlled level of shrinkability is retained in the film by only partly annealing the film. Such sausage casing film – which has a double function as processing aid for curing the sausage.
Polyamide based packaging
