The use of flow wrappers has transformed the way in which some industries such as food, pharmaceutical or cosmetics present and protect their products. The type of film and its design are two decisive factors in the final result of the packaging process: it will influence the operational efficiency as well as the final perception of the product by the consumer.
In this article we explain what heat sealable films are, which are the most commonly used in flow pack machines, what features a quality reel should have and how they can be customized for each application.
What are heat-sealable films?
Flow pack wrappers use heat-sealable films in reel form. During the packaging process, the film wraps around the product and seals on three sides: one longitudinal seal and two end seals, creating a compact, hygienic and attractive package.
Heat sealable films are plastic or multilayer materials that, when heat and pressure are applied, melt or adhere to hermetically seal a package. This property is key to the operation of flow pack machines, since the wrapping process is based on the formation of a film tube that is sealed around the product.
These films can be composed of one or several layers of different materials, each with specific functions: an outer layer for printing or resistance, an intermediate layer for barrier (gases, humidity, light) and an inner layer with sealing capacity. Thanks to this configuration, it is possible to adapt the package to the needs of product preservation, presentation or even recyclability.
In addition to being heat-sealable, the films used in flow pack must offer good mechanical strength, stable behavior at high speed and, in many cases, barrier properties that protect the contents from the external environment.
Films compatible with flow pack wrappers
Flow pack wrappers are compatible with a wide variety of materials.
BOPP
BOPP (biaxially oriented polypropylene) films incorporate a metallized or transparent layer that can be combined with other layers to improve sealing. They are known for their stiffness, tear resistance and excellent visual presentation. Main applications include snacks, industrial bakery, candy, dry goods and non-food items.
PET
PET (polyethylene terephthalate) film is noted for its thermal and mechanical strength. It can be used as an outer layer in multilayer structures, especially when high print quality and good dimensional stability are required. It is ideal for bars, chocolates, cosmetics and premium products.
PE
PE is very flexible and has high sealability. It is used as an inner layer in laminated films and allows hermetic sealing even in modified atmospheres. It is used for fresh, frozen or vacuum-packed products such as meat, cheese or vegetables.
Multilayer laminates (PET/PE, BOPP/PE…)
These films combine several layers with specific functions: a tough, printable outer layer, a middle layer with barrier properties and a sealable inner layer. They are extremely versatile. They are used for sensitive products such as food, cosmetics or pharmaceuticals.
Sustainable films
The market is increasingly demanding sustainable solutions. There are options for recyclable mono-material films (100% PE or PP) and heat sealable paper with biodegradable barrier. Sectors such as organic food, natural cosmetics or innovative packaging start-ups are already incorporating them.
According to Lucas Palma, general manager of the Barcelona Packaging Hub and CMO of Synchropack, “mono-materials are and will be a turning point to lead the packaging sector towards sustainability”.
What features should a film reel have?
A well-made film reel that is correctly adapted to the machine is key to the smooth running of the flow pack process. From its winding shape to its physical properties, everything influences the performance of the line.
The dimensions must be accurate: film width, outside diameter and mandrel size must match what is specified by the flow pack wrapper. An error in these measurements can cause misalignment, sealing errors and production stoppages.
Mechanical strength is another essential aspect. The film must withstand the pull of drag without breaking, and it must heat seal properly at the set temperature and pressure. The higher the machine speed, the more critical this point is.
In addition, the unwinding must be uniform. Undulations or poor centering cause jams and misalignments.
Customization on film reels for flow pack packaging
In addition to their technical functionality, the films used in flow pack machines offer a wide range of customization possibilities, making the packaging a powerful brand communication medium.
Among the most common design options are flexographic or rotogravure printing, the inclusion of markings for cutting and registration control, matte or gloss finishes, selective varnishes and product viewing windows.
Brands can adapt the reel design to promotional campaigns, product launches or sustainability strategies, including recyclability icons, instructions or visual claims.
In addition, it is possible to adapt the type of film (thickness, barrier, treatments) to the product life cycle, logistics and exposure conditions (refrigeration, sunlight, international transport, etc.).
