- Barrier filmsDescription
Barrier films are foils consisting of several layers, which in combination create a barrier layer. Generally, they are applied as packaging material in the food industry. However, they also provide appropriate packaging for sensitive products from medical technology and industry. Barrier films reliably limit oxygen permeability. Moisture, germs and spores are blocked out to the greatest possible extent. The barrier is composed of a material mix varying according to requirements. Barrier film is usually made of polyamide and polyethylene. Yet EVOH, PET, PP or Surlyn can be incorporated into barrier films as well. Barrier films are also extremely valuable for Modified Atmosphere Packaging (MAP), as they maintain the protective atmosphere supplied. Nitrogen (N2) and carbon dioxide (Co2) are retained in the packaging providing an extended shelf life. Barrier films are primarily intended for use as thermoforming packaging, as they serve to produce top and bottom films.
The barrier layers are generated during foil production by means of extrusion, in which several layers are placed on top of each other. The choice of material mix used is largely dependent on the intended purpose of the packaging. Barrier films not only represent functional packaging material, but can also be printed excellently (flexographic printing). The composite films’ outstanding machine compatibility and sealing properties make them particularly suitable for the production of vacuum bags.
- Blow extrusionDescription
Blow extrusion refers to the process of manufacturing blown film as produced by ALLVAC. In this process, molten plastic material is blown-out through a ring nozzle by means of air. The result is a 10 to 20 metre high melting hose, which is folded and wound up after cooling. The extruder represents the most important component in blow extrusion. It heats the plastic granulate and generates the required pressure to force the molten plastic through the ring nozzle. It is in this production phase that the thickness and diameter of the film is determined. ALLVAC manufactures films with a thickness between 50my and 300my. At this point, different numbers of barrier layers are also defined. PA/PE barrier film with seven to nine layers is a well-established scale. Regardless of the thickness, film always requires cooling before it is flattened by squeeze rollers and finally wound up.
- Blown filmsDescription
Numerous different packaging materials are produced from blown films. Starting substance is thermoplastic material in various formulas. ALLVAC manufactures blown films offering different barrier properties. Primary components are polyamide and polyethylene. Plastic granules are first heated on several special blown film extruders and pressed through a blow head with an annular gap, resulting in a vertical film bubble and subsequently a 10 to 20 metre tall film tube. Afterwards, the tubular film, virtually floating in the air, is finally cooled down and folded. In the next production step it is wound up by means of corresponding tools. ALLVAC manufactures thermoforming film as well as films for flow pack applications that wrap around the product like a second skin, for use especially in food processing.
Films produced by means of coextrusion consist of several layers of different materials. This process involves melting plastic granules in at least three extruders, from which the films are subsequently either cast or blown. Coextrusion in the blowing process entails combining the melt streams into a film via a multi-layer ring die. Coextrusion is more complex in the production of flat films. The polymer melts are combined via multilayer nozzle or adapter technology. The cast film, which is forced against the casting roll by means of a strong air jet, is allowed to cool down completely on the cast roll. This process enables a film to be manufactured from several granulates containing non-related materials.
- Coextrusion filmDescription
Coextrusion film is a plastic film with various properties. The distinctions result from material composition, thickness and the number of different layers. These parameters directly affect the barrier properties and sealing ability, as well as the degree of gloss and puncture resistance of the finished film. ALLVAC produces coextrusion films. In addition to the classic, a film made of polyamide and polyethylene, the portfolio also includes a material mix of renewable raw materials. The latest innovation, a recyclable barrier film of extreme purity, has been developed in the company’s in-house laboratory and application technology centre.
- Composite filmsDescription
Composite films are composed of different material layers, in most cases employing alternating layers of polyamide and polyethylene. They are used to produce flexible packaging. Composite films from ALLVAC are produced in up to 11 layers by means of two different processes: cast extrusion and blow extrusion. Thermoformed packaging or vacuum packaging produced from film mainly serves as food packaging. Composite film comprises of individual layers that can be combined in various ways depending on the specific application requirements. Each of ALLVAC’s composite films includes a barrier layer which reliably keeps oxygen, moisture, germs and spores from entering the packaged goods.
Ethylene-vinyl alcohol copolymer, EVOH for short, is a copolymer composed of the monomers ethylene and vinyl alcohol. In films from ALLVAC, EVOH is extruded. Its properties depend on the proportion of ethylene within the copolymer. EVOH is particularly effective as a barrier layer in packaging food products using this type of film. The excellent barrier properties of EVOH ensure a significantly increased shelf life.
The extruder, also known as screw extruder or screw press, is the key component in the production of thermoplastics. For manufacturing film, the plastic granulate is first filled pneumatically from silos into containers, weighed in batches and passed through a vertical opening into the extruder feed section. Once there, it is fed to a rotating screw, melted down and conveyed by one or more screws to the extruder outlet. The heated metal cylinder, housing a rotary plasticizing screw, stands out as a special feature. By conveying the molten plastic, pressure is built up to ensure that the molten mass is forced through a narrow mould slot, which provides for the shaping. In blown film extrusion, the molten mass emerges from an annular die and creates the film tube, ready to be inflated. In cast film extrusion, the melt emerges from a wide slot die in order to subsequently cool down on a horizontal cylinder.
- Film made from renewable raw materialsDescription
Films made from renewable raw materials contain the raw materials polyamide and polyethylene, which are no longer obtained from crude oil, but instead from rapeseed oil or sugar cane. This specific film type achieves a barrier quality of the same level. Although ALLVAC is able to produce these films, the company now draws attention to the latest generation of films, which are recyclable and of extreme purity and consequently can be fed back into the closed loop economy.
- Film tubeDescription
When producing film by means of blown film extrusion, liquid plastic emerges through ring dies and is blown upwards as a film tube forming a column 10 to 20 metres high. The flattened blown film is wound up into a full tube and subsequently processed into bags or sacks. A tubular film has no side seams, which makes it particularly attractive for packaging. A distinction is made between single-layer films, so-called mono blown films and multi-layer films, which are called coextrusion blown films. ALLVAC has specialised in producing them. The films are characterized by their excellent barrier properties. The desired effect is that foodstuffs, for example, have longer shelf lives, as oxygen, moisture or germs are reliably prevented from gaining access to the packaged goods. Moreover, a packaging solution based on a film tube also allows sensitive non-food products to be perfectly wrapped.
- Flexo printingDescription
Flexo printing is a web-fed rotary printing process employing flexible printing plates, so-called clichés, and low-viscosity printing inks. Flexo printing is primarily applied to print packaging materials, such as barrier films from ALLVAC. This method allows for printing basic information onto the film, such as the ingredients or even entire advertising messages. The films can be printed with up to ten colours offering a wide range of creative design options. Print quality is excellent and colours are brilliant. Printing is not limited to the surfaces of a packaging. Interlayer printing is equally possible. Medium and large size batches are ideally suited for this printing method.
- Oxygen barrierDescription
An oxygen barrier becomes essential when packaging particularly sensitive products such as meat, sausage, fish or cheese. Pet food (BARF) and cosmetics benefit equally from packaging that includes an oxygen barrier. It prevents the rapid spoilage of a product while slowing down the oxidation process of meat. Pre-prepared potatoes, for example, require packaging including an oxygen barrier, as without they tend to turn black. In foil production, polyamide and EVOH serve as a barrier layer to ensure virtually no oxygen enters the products.
PET refers to polyethylene terephthalate, a plastic material within the polyester family. Our film production processes simply would not be complete without it. The range of applications this material can be used for is extremely diverse. It is processed into plastic bottles, but also textile fibres and of course into films. PET exhibits polar properties, which means that strong intermolecular dynamics are involved. The molecule also has a linear structure without cross-linking. Both factors render semi-crystalline structures and fibres possible. Increased resistance to fracture and deformation is a further important feature. Packaging films containing PET retain the aroma of food products exceptionally well.
Polyamide is one of the main components in ALLVAC’s barrier films. Polyamides are linear polymers containing regularly repeating amide bonds along the main chain. Their most valuable properties include strength and resilience. In addition, they are characterized by excellent aroma and fat density as well as extremely high resistance to heat and cold. Besides that, they tolerate organic solvents. However, they are not resistant to acids and oxidizing solvents. In common parlance, the term “polyamide” stands for thermoplastics and establishes a distance to chemically related proteins.
Polyethylene is a thermoplastic material produced by polymerisation of ethylene; it is semi-crystalline, non-polar and belongs to the polyolefin group. By far the most widely used plastic material in the world it is primarily applied in the production of packaging – therefore it is also a key component in ALLVAC’s film production. It distinguishes itself by its high chemical resistance as well as a convincing sealing ability and water barrier. As a composite material for our barrier films, it thus ensures particularly smooth machinability in thermoforming packaging processes. Owing to their special properties, however, polyethylenes are also employed in other production processes. Their chemical composition allows them to be used to produce not only soft but also hard plastics, as well as waxes, lubricants or even oils.
Polypropylene is highly valued in our film manufacture for its outstanding tear resistance, which is ensured by the chain polymerization of propene. Whenever polypropylene is not an integral part of barrier films, it is often found as the main component in adhesive packaging tapes. Its properties are similar to those of polyethylene, but it is slightly harder and more heat-resistant, but equally semi-crystalline and non-polar. Thermoplastics are used second most frequently as standard plastics, especially for packaging. The melting and continuous operating temperature of polypropylene is generally higher in comparison to polyethylene. Polypropylene also surpasses polyethylene in rigidity, hardness and strength.
- Sealing propertiesDescription
Efficient sealing seams are an essential feature of flexible packaging, as they provide an airtight closure and thus ensure longer shelf life for food products as well as optimum protection for sensitive products during transport and storage. Sealed seams result from applying heated tools and pressure to the films so that they fuse together or become peelable. This may sound simple, but it is not, as obtaining the desired bond requires sufficient heat exposure and appropriate length of time for the sealing process to be completed. Too low a temperature or too short a time period will not allow the seam to be fully closed. The appropriate amount of pressure is equally important, as polymers do not melt completely under sealing temperatures and therefore require the application of sufficient force for the molecular chains of the plastic to bond together.
The amount of temperature, time and pressure required depends on the composition of the film as well as the type of goods to be packaged. The process must still run smoothly, even if the film or sealing tool has been contaminated with product fluids or blood, as is often the case with meat packaging, for example. Films manufactured by ALLVAC have undergone a series of test runs in the company’s in-house application technology centre, enabling us, based on our extensive experience, to determine the sealing properties of each individual type. To ensure reliability, ALLVAC or the customer himself may conduct test runs to examine the sealing properties of special film types very thoroughly – even under a microscope, if necessary. By then at the latest, our experienced team will identify for you the optimum film with the best sealing properties to suit the product to be packaged.
- Shelf life expiration dateDescription
The shelf life expiration date (SLED) is a marking element required by law. It is subject to EU law and Swiss law. It must be displayed on all finished packages to indicate the minimum shelf life of a food or pharmaceutical product under appropriate storage and handling conditions. If the shelf life expiration date is exceeded, there may be a loss of taste and quality. Health risks may also evolve beyond expiry of the SLED. Cosmetic products that cannot be stored for at least two and a half years must carry an expiration date as well.
The minimum shelf life of a food product is at the discretion of the producer. It is therefore possible that different producers of the same product may declare different SLEDs. Highly perishable foods, such as minced meat, do not display a shelf life expiration date, but rather a consumption date that indicates by when the product should be considered processed. The shelf life expiration date is comparably more significant, as it is based on best before tests.
- Transport packagingDescription
Transport packaging facilitates the transport of goods while protecting them from damage or external influences in transit. In Germany, the handling and requirements for transport packaging are regulated by the Packaging Ordinance. For Austria we follow the Shipping Container Ordinance. The consulate and sample regulations serve as a reference book for foreign packaging regulations. Barrier films from ALLVAC protect particularly sensitive products such as food or items for medical technology against spoilage during transport, providing optimum resistance to moisture, oxygen and dirt. Apart from that, flexible packaging serves as an especially space-saving transport solution.
- Vacuum packagingDescription
Vacuum packaging describes gas-tight packaging of a product, in which the spaces between the product and the reactive gases within the product have been virtually eliminated by air extraction. The extraction of oxygen from the packaging is essential, as it significantly delays food spoilage. Vacuum packaging involves at most a rough vacuum where the flexible plastic film is propped up against the ambient air pressure by the packaging content. Vacuum packaged goods are marked as: “packed under vacuum”. The fact that vacuum packing reduces the volume of the packaging to a minimum is an additional advantage. ALLVAC produces numerous types of barrier films that can be applied for vacuum packaging. They are also used to manufacture our sister company ALLFO’s vacuum bags.