Types of Film used in the Packaging Industry:
Polyethylene – Due to its excellent properties and the variety of possible uses, polyethylene is the most common and the most useful type of film for packaging. There are three, basic production methods:
- LDPE – Low-density polyethylene is the plastic industry’s main product. It is used for packaging, wrapping and covering. The film is flexible, has a high tensile strength, is relatively impermeable to water vapors and can be shaped into different forms. It also serves as the internal, bonding layer of laminates.
- LLDPE – Linear low-density polyethylene is characterized by: excellent tensile strength, flexibility, exceptional stretching qualities, highly resistant to rips and punctures, excellent bonding and serves as an alternative to LDPE.
- HDPE – High-density polyethylene has extensive tensile strength, rigidity and excellent stretching qualities. It is highly impermeable to water vapors and grease.
Other polymers, such as EAA, Ionomer and AVE, improve performance levels of bonding and sticking in comparison to polyethylene and their use is becoming more extensive. Polypropylene excels in its high levels of transparency and gloss, is more resistant to high temperatures than polyethylene and has average bonding qualities. All of the films surveyed so far are used primarily as internal layers and for the bonding of a variety of laminates.
The following films are used as an external layer for double-layered laminates or as an intermediate layer for multi-layered laminates:
1. PET – The outstanding properties of polyester include transparency and excellent gloss. It also has a high tensile strength, even at thin levels of thickness, is highly impermeable to oxygen and the penetration of grease, and its properties remain intact even at extremely high temperatures. These properties are primarily characteristic of films processed with a bi-axial orientation of polyester. This technology is commonly used to significantly improve the tensile qualities of numerous film types.
2. PVDC – Coated polyester: The coating significantly improves the barrier properties of the film. Laminates with coated polyester are used for vacuum packaging of cheese, meat, fish and the like.
3. PA – Nylon: The film excels in high levels of tensile strength and flexibility. It can be vacuum shaped is resistant to the transmission of gases and the penetration of grease.
4. BOPA – Bi-axially Oriented Nylon: Processing with this technology improves the film’s tensile strength and its resistance to the transmission of gases, in comparison to regular nylon, but negates the ability to vacuum shape the film.
5. BOPP – Bi-axially Oriented Polypropylene: Additional processing of the polypropylene improves many of its properties, such as: tensile strength, rigidity, transparency, gloss and resistance to the transmission of water. However, its bonding abilities are reduced. The co-extrusion line technology enables higher bonding levels.
6. BOPP Polypropylene coated with PVDC – The coating improves the barrier properties of the BOPP, against the penetration of oxygen as well as the penetration of water vapors. The film is used in laminates for snacks and other items that are sensitive to oxygen transmission.
7. BOPP Melted Polypropylene – The film is coated with a thin layer of aluminum. The melting process contributes to its resistance to light rays and significantly improves its resistance to the transmission of water vapors. The film is used in laminates for sweet and salty snacks.
8. CAST Polypropylene – Its properties include high levels of transparency and gloss, high bonding strength and relatively low oxygen barrier properties in comparison to other polypropylene films. It is used primarily for packaging of agricultural produce, flowers and textiles and as a film in multi-layered laminates for reinforcing bonding and mechanical strength.
9. Different types of paper – Properties include mechanical strength and stability, excellent printing properties and rigidity for improving the package composition. The film has no barrier properties against the transmission of oxygen, gases or moisture.
10. PVDC Coated Cellophane – This is one of the veterans in the field of laminated films. It is manufactured by a process of regenerated cellulose and coated with PVDC to make it more sealable against gases and water vapors. Its primary properties include: high transparency and glossiness, relatively sealable against gases and water vapors. Lately, the use of this raw material in paper films has been decreasing.
11. Aluminum Foil – Aluminum foil is used primarily in laminates that must be highly sealable against gases, water vapors or light rays. The foil serves as a complete sealant. Another property is its rigidity, even when very thin. In addition, its unique visual properties can be utilized for graphic design purposes.
12. P.L.A. Polylactic Acid Films – Polymers and films made completely from plant or vegetal sources such as corn starch.
A new generation of natural, raw materials for the manufacture of films and packaging, approved for contact with food products, with high transparency and qualitative gloss, high quality printing properties and good resistance to oxygen, aroma and grease transmission. The films are partially sealable to moisture but with the advantage of offering a long shelf life, they are widely used for packaging fresh produce.
The film is biodegradable and is transformed naturally into H2O or CO2 by the micro-organisms in the soil. These qualitative properties of an additional raw material for traditional plastic films endow PLA with a promising future and give it new and extra advantages in the packaging industry in general, and for flexible packaging in particular.
The various films can be improved by a variety of coatings. Coating with different solutions can improve the sealable level of the film, it smoothness or roughness and can prevent the accumulation of static electricity. Certain properties found in aluminum foil or those similar to paper can be added to the film by special metallizing techniques.
13. A Look Towards the Future – Flexible Films and Packaging – The different types of films, primarily those based on plastics, and the new groups of coatings and polymers offer a growing market for flexible packaging in the field of consumption. They are a novel concept serving as an alternative to traditional materials such as glass, wood, paper and metal. The films’ many advantages offer alternative solutions to rigid packaging (containers, bottles, cardboard boxes, cans, etc.) from numerous perspectives, including logistics and shipping, environmental aspects, recycling, reducing volumes, novel perceptions for usage and economic considerations.