The language of flexible packaging is a specialized terminology that is used in the design, manufacturing, and marketing of flexible packaging materials. It includes terms related to the physical properties of the materials used, such as barrier properties, tear resistance, and flexibility, as well as the different types of packaging formats, such as stand-up pouches, flat pouches, and bags.
Understanding this enables effective communication between manufacturers, suppliers, and customers. Additionally, it allows designers to create packaging solutions that meet the specific needs of their clients, such as keeping products fresh, protecting them from damage, and making them more convenient to use
Absorbent packing: material within a package that absorbs liquids from a product; pad in meat trays is made from paper and has a plastic liner.
Anilox Roll: Engraved ink metering roll used in flexo presses to provide a controlled film of ink to the printing plates which print onto the substrate.
Anti-Block: The name for a treatment applied to plastic film surfaces to keep them from sticking together or “blocking” when they are tightly rolled up on a mandrel.
Aseptic packaging: a technique for creating a shelf-stable container by placing a commercially sterile product into a commercially sterile container in a commercially sterile environment. The sealed container is designed to maintain product sterility until the seal is broken.
Barrier Properties: refer to the ability of a material to prevent the passage of gases, liquids, or other substances through.
Base Film: The original form in which a film exists before coating or laminating.
Beta Gauge: Consists of two facing elements, one emitting and one detecting beta radiation. The device accurately measures density or thickness when mounted above and below the web.
Biaxial Orientation: Orientation of plastic films in both machine and cross machine (transverse) directions by stretching. Biaxial stretched films are generally well balanced in both directions and much stronger in terms of tear strength.
Bioplastics: are a type of plastic that is made from renewable resources, such as starch and cellulose. They are commonly used to produce eco-friendly plastic films and flexible packaging.
Blister packaging: the item is secured between a preformed (usually transparent plastic) dome or “bubble” and a paperboard surface or “carrier”; also referred to as a “bubble pack.” (example: bologna package hanging on a peg in a supermarket’s refrigerated case).
Block, Blocking: Undesired adhesion of two or more plies of material in roll or sheet form. May be caused in cellophane by exposure to excessive heat, pressure or humidity; in printed film, occasionally caused by improper or insufficient drying of inks, resulting in printed areas sticking together.
Boil-in-bag: a sealed container made of heat-resistant material designed to hold a food product and permit the ultimate user to bring the bag and product to boiling temperature in preparation for eating before the product is removed from the bag. (example: frozen entrees or vegetables).
Breathing package: packaging material made in such a manner that air may enter or leave under varying conditions, including temperature changes, with or without a drying agent to remove moisture from entering the package. Most wrap used for fresh red meat allows enough air to pass through to keep the proper color in the meat.
Burst Strength: A measure of the ability of a sheet to resist rupture when pressure is applied to one of its sides by a specified instrument under specified conditions.
Cast Film: Plastic film produced from synthetic resins (such as polyethylene) by the cast process. In this process, the molten resin is extruded through a slot die onto an internally cooled chill roll.
Cast Nylon (CAN): Film used mostly for thermoformable packaging applications.
Cellophane: Transparent film made from regenerated cellulose, a fibrous material occurring in plants.
Chemical Resistance: Ability of a material to retain utility and appearance following contact with chemical agents. Chemical resistance implies that there is no significant chemical activity between the contacting materials.
Clarity: Freedom from haze; transparency.
Controlled Atmosphere Packaging (CAP): a packaging method in which selected atmospheric concentrations of gases are maintained throughout storage in order to extend product shelf life. Gas may either be evacuated or introduced to achieve the desired atmosphere. Normally used for fruits and vegetables, not meat products.
Coefficient of Friction (COF): A measurement of “slipperiness” of plastic films and laminates. Measurements are usually done film surface to film surface. Measurements can be done to other surfaces as well, but not recommended, because COF values can be distorted by variations in surface finishes and contamination on test surface.
Co-extrusion – a process of extruding multiple layers of material simultaneously to create a composite material with specific properties.
Corona Treatment: A treatment to alter the surface of plastics and other materials to make them more receptive to printing inks.
Cross-Linking: A film conversion technique in which polymer chains are bound into a web or network to increase the web’s heat stability and strength.
Crystallized Polyethylene Terephthalate (CPET): a heat-tolerant plastic that can be molded into multi-compartment and single frozen food containers; can be heated in the microwave or conventional oven.
Delamination: Separation or splitting of laminate layers caused by lack of or inadequate adhesion, or by mechanical disruption such as peeling or shearing forces.
Dimensional Stability: The absence of dimensional change of a material when subjected to changes in temperature, humidity, heat or aging.
Doctor Blade: Scrapers that regulate the thickness of adhesives, or inks, on a feed roller.
Dyne: A measurement unit of force (centimeter-gram-second) traditionally used to quantify the energy on the surface of a film as an indicator of its ability to accept inks or coatings.
Elmendorf Tear Test: A method of testing film for resistance to tearing. The weight required to tear one of several layers of notched film is measured.
Emulsion: A non-separating dispersion or suspension of a solid in a liquid.
Ethylene Acrylic Acid (EAA): EAA is a copolymer of ethylene and acrylic acid. lts ionic nature allows for excellent adhesive bonding to metal foil and other polar surfaces. EAA’s adhesive and toughness qualities are taken advantage of in high performance multi-layer laminates.
Ethylene-Ethyl Acrylate (EEA): The copolymerization of ethylene with ethyl acrylate produces an ethylene acid copolymer. The polymers are produced with varying percentages of acrylate content, most typically between 15 and 30%. EEA is compatible with all olefin polymers and often is blended with these to modify properties. EEA is used in hot-melt formulations. lt also can be used alone or as a component of heat-sealable coatings where it offers improved toughness at low temperatures, excellent adhesion to nonpolar substrates, and a broad service temperature range. EEA is used as a tie layer between mating laminate films.
Ethylene-Methyl Acrylate (EMAC): The copolymerization of ethylene with methyl acrylate produces an ethylene copolymer, one of the most thermally stable of the olefin copolymers. The polymers are produced with varying percentages of methyl acrylate content, most typically between 1 8 and 24o/o of the structure. Alone or in blends, it has found applications in film, extrusion coating, sheet, laminating, and co-extrusion.
Ethylene-Vinyl Acetate (EVA): A polar copolymer of ethylene and vinyl acetate, retaining some of the properties of polyethylene but with increased flexibility, elongation, and impact resistance. EVA is frequently specified as the extrusion coating on polypropylene, aluminum foil and poly(ethylene terephthalate), to provide good heat-seals at high converting rates, or as the adhesion layer in some laminates.
Ethylene-Vinyl Alcohol (EVOH): Can be regarded as a copolymer of polyethylene in which varying amounts of the -OH functional group have been incorporated. A typical packaging EVOH is about 20 to 35% ethylene. EVOH is one of the best polymeric oxygen barriers available to packagers. However, its susceptibility to water requires that for most applications it be laminated or co-extruded into a protective sandwich with materials that will keep the EVOH layer away from water.
Extrusion Coating: A process where a film of molten polymeric material is extruded onto the surface of a substrate material and cooled to form a continuous coating.
Extrusion Lamination: A laminating process in which individual layers of multi-layer packaging materials are laminated to each other by extruding a thin layer of molten synthetic resin (such as polyethylene) between the layers.
Eye Mark Register: A printed rectangular mark most often found along the edge of rollstock that can be identified by an electric eye. The mark identifies a point on the web where an individual package is to be cut.
Fiberboard can: a rigid container constructed almost completely of lightweight fiber stock; may be lined, treated or coated; ends of can may be made of paperboard or metal (composite can). (examples: packaging used for juice concentrates, potato sticks and onion rings)
Film: Generally used to describe a thin plastic material usually not more than 75 micrometres (0.003 inch) thick.
Film, Calendered: A film manufactured by forcing base material through rolls of a calendering machine, making it smooth and glossy.
Film, Cast: (1) Film made by pouring or metering material onto a highly polished moving drum or endless belt, or (2) film produced by extruding into a solution, as in the case of cellophane.
Film, Density: The ratio of the weight of a body to the weight of an equal volume of water at some specified temperature.
Film, Extruded: Film produced by the extrusion method.
Film, Extrusion: The process of forming a thermoplastic film, container, or profile by forcing the polymer melt through a shaped orifice.
Film, Non-Fogging: Film that does not become cloudy from condensation of moisture caused by temperature drops or humidity changes.
Film, Orientation: The process of mechanically stretching plastic film or parts in order to produce a straightening and alignment of the molecules in the stretch direction. If done in one direction, the material is said to be uniaxial or monoaxially oriented. If done in two directions, the film is biaxially oriented.
Fin Seal: Seal that results when edges of two superimposed sheets are bonded, resulting in a pouch having fin-like protuberances.
Finishing: Any final operation done to packaging before shipping.
Fish Eyes: Particles of undissolved extraneous material in a film or coating.
Fitment: A device attached to the container finish to provide a performance function. For example, a pour-out fitment is plastic component for a glass, plastic or metal package, designed to improve the dispensing action of liquid products.
Flexible container: bags, envelopes, pouches or wraps which can be changed in shape or bent manually; made of materials such as paper, plastic film, foils, etc., or combinations of them.
Flexible Packaging: refers to a type of packaging that is made of flexible and easily moldable materials, such as plastic, aluminum, and paper.
Flexographic Printing: A method of printing using flexible rubber or photopolymer printing plates in which the image to be printed stands out in relief. Fluid ink metered by an engraved roll is applied to the raised portions of the printing plate and then transferred to the substrate.
Form-Fill-Seal (FFS): A packaging machine that forms, fills, closes and seals a package in one continuous or intermittent-motion operation. Flexible packaging stock fed from a roll is folded to the desired package shape and stabilized by heat sealing. The product is placed into the formed package, and the remaining opening is sealed. Machines can be configured so that the stock travels horizontally through the machine (horizontal form-fill-seal, HFFS) or vertically through the machine (vertical form-fill seal, VFFS).
Four-Color Process: Printing with cyan, yellow, magenta, and black ink (CMYK) using halftone screens to create a full color reproduction.
Fractional Packaging: Interior packaging of individually wrapped units so that unused portions will be protected after outside package has been opened. Usually used for biscuits, crackers and ready-to-eat cereals.
Gas Transmission Rate (GTR): The quantity of a given gas passing through a unit area of the parallel surfaces of a film, sheet, or laminate in a given time under the test conditions. Test conditions may vary and must always be stated.
Gauge: Thickness. In North America, film thickness, measured in mils, is usually given in gauges. A 100 gauge shrink film is one mil, or 1/1000 of an inch, thick. In Europe, the film thickness metric is the micron. A quick equivalency equation is: 1 mil = 25.4 microns.
Gauge Band: A thickness irregularity found in rolls of film. A thicker area in the machine direction at some location across the width of a flat film will produce a raised ring in a finished roll. Gauge bands can cause winding problems and when unwound, the material tends not to be perfectly flat.
Gas Transmission: The movement of gas, air, oxygen, etc., through a film material. The gas transmission property (permeability) of a film is measured in terms of the volume of gas (at standard temperature and pressure) transmitted through a given area of film of a given thickness, within a given time.
Gel: A general term used to describe a defect consisting of insoluble polymer causing a visible discontinuity in a film.
Ghosting: Reproduction, very faint, of printed design without actual ink transfer.
Glassine: smooth, dense, transparent or semi-transparent paper manufactured primarily from chemical wood pulps; is grease resistant and has a high resistance to the passage of air. May be waxed, lacquered or laminated to be impervious to the transmission of moisture vapor. White and colors.
Heat-Seal Strength: Strength of heat-seal measured after the seal is cooled, (not to be confused with “hot tack”, see next item).
Heat Sealing: A method of bonding two or more surfaces by fusing thermoplastic or thermosetting coatings of films under controlled conditions of temperature, pressure and time (dwell).
Hermetic Seal: Airtight or impervious to gases or fluids under normal conditions of handling and storage.
HFFS: Abbreviation for horizontal form-fill-seal.
High Barrier: Describes a material or package that has very low gas permeability characteristics; that is, it offers a great deal of resistance to the passage of a gas through its volume.
High-Density Polyethylene (HDPE): is a type of polyethylene known for its high strength, durability, and resistance to moisture and chemicals. It is commonly used in the production of plastic films and flexible packaging.
Hot Tack: Strength of heat seal measured before the seal is cooled, which is very important for high-speed packaging operations.
Lamination: is a process of bonding two or more layers of material together to create a thicker and more durable material.
Low-Density Polyethylene (LDPE): is a type of polyethylene known for its flexibility, clarity, and resistance to moisture and chemicals. It is commonly used in the production of plastic films and flexible packaging.
Lap Seal: A seal made with two layers of film overlapping one another. Because lap seals require less material than fin seals, packagers are converting to lap seals in the name of sustainability, lean operations and economics.
Laser Scoring: Use of high-energy narrow light beam to partially cut through a material in a straight line or shaped patterns. This process is used to provide an easy-opening feature to various types of flexible packaging materials.
Lidding, Lidstock: Material or stock used to form a lid. For example, material that can be heat-sealed over the open ends of pharmaceutical tablet blister cards.
Light Resistance: The ability of material to withstand exposure to light (usually sunlight or the ultraviolet part of the light spectrum) without change of color or loss of physical and/or chemical properties.
Linear Low Density Polyethylene (LLDPE): Tougher than LDPE and has better heat-seal strength, but has higher haze.
Lip: That part of the tube of a flat or square bag, or pouch, extending beyond the face of the bag.
Lithography, Offset: Printing process using etched metal plates. Ink adheres to etched area, is transferred to rubber printing blanket, from there to paper to be printed.
Metalized Film: a type of flexible packaging material that has a thin layer of metal, usually aluminum, applied to it to enhance its barrier properties.
Migration: transfer of a component of a packaging material into the product contained, or loss of a component of the product into the packaging material.
Modified Atmosphere Packaging (MAP): a packaging method in which a combination of gases such as oxygen, carbon dioxide, and nitrogen is introduced into the package at the time of closure. The purpose is to extend the shelf life of the product packaged. (example: lunch meat in a blister package).
Moisture Vapor Transmission Rate (MVTR): is a measure of the amount of water vapor that can pass through a material over a given period of time.
Netting (plastic): continuous extruded net of flexible plastic material, most commonly polyethylene, which can be made into bags, sleeves or wraps. (example: net over a frozen turkey package).
Nylon: is a versatile family of thermoplastic resins that vary from relatively flexible products to tough, strong, and stiff materials; resistant to oils and greases; widely used for meat and cheese packaging, for boil-in-bags and pouches.
Oriented Polypropylene (OPP):. This polypropylene film is monoaxially stretched in either the transverse or longitudinal direction. OPP plastic can be used in many applications including tapes, labels, and packaging.
Oxygen Transmission Rate (OTR): a measure of the amount of oxygen that can pass through a material over a given period of time.
Packaging: the enclosure of products in a wrap, pouch, bag, box, cup, tray, can, tube, bottle or other container form to perform one or more of the following functions: 1. containment for handling, transportation, and use; 2. preservation and protection of the contents for required shelf and use life; 3. identification of contents, quantity, quality and manufacturer; 4. facilitate dispensing and use.
Plasticizer: material added during the manufacturing process to increase flexibility; for example, the plasticizer ATBC (acetyl tributyl citrate), used in such DowBrands™ as Saran™ and Handiwrap™, is made from citric acid which is commonly present in citrus fruit.
Polyester (PET): is a synthetic polymer that is used in the production of plastic films and flexible packaging. It is known for its high tensile strength, durability, and resistance to moisture and chemicals.
Polyester, thermoset: filled plastic which is heated to harden into a shape and does not soften when heated during normal cooking temperatures; example: plastic dishes in frozen dinner entrees; can be heated in the microwave or conventional oven.
Polyethylene Terephthalate (PET): a thermoplastic polyester used in beverage bottles and food trays designed for microwave and conventional ovens.
Polyethylene (PE): is the most commonly used material in the production of plastic films and flexible packaging. It is a thermoplastic polymer known for its flexibility, durability, and resistance to moisture and chemicals.
Polyethylene film: the most-used transparent flexible packaging material; made from polyethylene, a synthetic clear compound formed by subjecting ethylene, a gas found in coal, to pressure. It is low cost, transparent, tough, heat sealable, moisture-proof and resistant to low temperatures.
Polypropylene (PP): a synthetic resin plastic packaging material used for microwave-only heating of foods with low fat and sugar content; not heat stable for use in conventional ovens. It is a thermoplastic polymer that is known for its high strength-to-weight ratio and clarity.
Polystyrene (PS): is a thermoplastic polymer that is used in the production of plastic films and flexible packaging. It is known for its clarity, rigidity, and resistance to moisture and chemicals.
Polyvinyl Chloride (PVC): replaced cellophane as the preferred meat wrapping used in supermarkets; a member of the vinyl family made from a compound found in petroleum. Low cost, protects against moisture loss, but has some oxygen permeability so it allows meat to “bloom” (stay red and fresh looking).
Polyvinylidene Chloride (PVDC): a thermoplastic polymer that can withstand higher temperatures than polyethylene; especially useful for covering utensils when microwaving foods; moisture-proof and transparent. (example: Saran Wrap™)
Retort packaging: a flexible container typically formed from aluminum foil and plastic laminates. Can withstand in-package sterilization of the product, and, like metal food cans, can provide a shelf-stable package for foods.
Seal Strength: refers to the strength of the bond created between two layers of flexible packaging material when they are heat-sealed together.
Shrink wrapping: plastic film that shrinks when heated, producing a tight, neat fit; the most popular form of grocery store meat packaging is PVC wrapping with foam trays.
Vacuum packaging: rigid or flexible containers from which substantially all air has been removed before sealing. Carbon dioxide or nitrogen may be introduced into the container. This process prolongs shelf life, preserves the flavors and retards bacterial growth.
References
Glossary of Packaging Terms, Sixth Edition, Compiled and Published by The Packaging Institute International, 1988, ISBN 0-86512-951-7.
Packaging Foods with Plastics, by Wilmer A. Jenkins and James P. Harrington, Technomic Publishing company, Inc., 1991, ISBN 87762-790-8.