Expert knowledge from A-Z

Specifies the strength of a seal seam; influenced by sealing pressure time, temperature and the length of the substrate. Higher temperatures result in higher strengths.

Sealed-rim pouches have properties such as good weldability, water vapour tightness, oxygen barrier, flavour preservation, high tensile strength and good printability. Use: Vacuum packaging, fumigation of food, pharmaceuticals, cosmetics, chemicals and technical products.

Thermoplastic materials, such as PP, can be easily welded at the corresponding temperature. Temperature, pressure and time are crucial for the quality of welding for all welding methods. Methods: Thermal pulse, heat contact, separating seam, ultrasonic and high frequency. Corona pretreatment and having too much colouring or additives can affect the weld strength. Sealing means binding film surfaces using "seal seams" or "seal surfaces," usually by applying higher temperatures. The word "sealing" actually applies to film that cannot be welded, e.g. aluminium foil or cellophane which are made suitable for welding by applying sealing layer. Sealing is used in many methods of film processing, particularly for manufacturing and sealing bags or sacks, for attaching cover films to cups or bowls, for shaping, filling and sealing methods, and for manufacturing blister packs. Heat sealing is most common today, cold sealing is limited to special applications.

Sealing temperature (sealing range) is the temperature at which the surface of a film melts and firmly attaches to itself or to another film after cooling. The exact determination of the sealing temperature is associated with many years of experience. It is specified in a broad range, e.g. 90 °C - 180 °C for cellophane, 120 °C - 140 °C for BOPP; it also depends on the speed and number of cycles.

Human sensory organs (eyes, nose, ears and mouth) are used for testing and measuring purposes.

Stand-up pouches with stamped outlines in special shapes.

Made of thermoplastic materials and contract in the presence of heat. The memory effect is generated during the manufacturing process by stretching and cooling the film, essentially freezing it in place. This effect restores the original condition when the material is heated again.

Tubular wrap-around labels that contract when exposed to heat and shrink to the container, allowing them to be fixed in place with adhesive.

Shrink sleeve: Film is placed over containers and shrunk in a heat tunnel; it creates the impression that containers and labels are one. Stretch sleeve: Film is pulled around the container without adhesive in the form of a 360 degree decoration.

Isolated impurities in the film web, which negatively affect the film properties; the risk of tearing the film web is increased. Causes of specks: Undissolved granules or additive particles in the melt, foreign impurities (dust/dirt), from the environment in raw materials or in the manufacturing process of the film. Cross-linked or high molecular weight fractions in the polymers in use which do not melt completely. Due to temperatures being too high, damaged raw material (incorrect process control system) or unsuitable formula, recycling of thermoplastics, reuse of regranulated raw material. Impurities present on the nozzle gap or precipitated additives. For films with filling materials (opaque BOPP films), this can lead to the formation of specks in the event of poor distribution. Individual polymers have different tendencies for forming specks. Heat-sensitive products are particularly susceptible. This is true for materials such as PVC and polyamide.

See: Splice

Stable bags, usually made of composite film and often featuring a reinforced base for extra stability. Often equipped with a snap fastener, carrying handle opening or filling spout.

Method used to remove living micro-organisms from materials and objects; all of the micro-organisms present, their spores as well as viruses and plasmids are destroyed. Removal or killing off all micro-organisms in every stage of development Including: Steam sterilisation (heating in a damp state); Hot air sterilisation (heating in a dry state); Fractional sterilisation (multiple phases at 100 degrees and room temperature); Radiation sterilisation (with ionising radiation).

Usually made from LLDPE, highly elastic and usually transparent. The film thicknesses vary between 15 and 25 µm; they are used to wrap goods and for safely transporting pallets. Alternative to shrink film hood.

Tubular, flexible labels, which are pulled into place over containers without adhesive or temperature treatment.

Material receiving printing (e.g. film)

The irreversible formation of wrinkles and folds in film material, a phenomenon to watch for in thin films in particular. The reasons for this stem from the migration of mineral-oil-based printing inks or non-organic substances into the polypropylene matrix, and from waiting an insufficient period after printing onto the products to be packed in film or insufficient drying of the printing ink in the print operation. As the amount of recycled paper increases, it is also important to keep in mind that mineral oil-based substances may, in turn, find their way into paper and/or cardboard through the increased proportion of recycled materials. These mineral oil-based papers and cardboards are prohibited in food applications. In regards to film applications, PLA is currently resistant against swelling.