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FILM DEFINITIONS

 

Adhesive Lamination
A laminating process in which individual layers of multi-layer packaging materials are laminated to each other with an adhesive

Biaxial Orientation
Orientation of plastic films in both machine and cross machine directions by stretching. Biaxially stretched films are generally well balanced in both directions and much stronger in terms of tear strength.

Blown Films
Plastic films produced from synthetic resins (such as polyethylene) by the blown process. In this process, the molten resin is extruded through a circular die into a tube. This is expanded ("blown") by internal air pressure into a larger bubble with a much reduced wall thickness and cooled with external air quenching.

BON
Biaxially oriented nylon film, with excellent oxygen and aroma barrier properties (see NYLON) but is a poor water vapor barrier. BON is much stiffer than cast nylon film but cannot be thermoformed.

CAN
Cast nylon film (see NYLON). Used mostly for thermoformable packaging applications.

CAPP or CPP
Cast PP film. Unlike OPP (see PP), it is heat sealable but at much higher temperature than LDPE thus it is used as a heat seal layer in retortable packaging. It is however not as stiff as OPP film. (PP = polypropylene)

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.

Cold Seal
A pressure sensitive adhesive coating on plastic films or laminates that will allow the packages to be sealed by application of pressure (with no heat or minimal heat).

Coextrusion
Simultaneous extrusion of two or more different thermoplastic resins into a sandwich-like film with clearly distinguishable individual layers.

COF
Coefficient of fiction, 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.

Doy-Style Stand Up Pouch
A stand up pouch that has seals on both sides and around the bottom gusset.

EAA
Ethylene acrylic acid copolymer. Because of its excellent adhesion to aluminum foil it is mostly used for extrusion lamination of foil to other surfaces.

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.

EVA
Ethylene-Vinyl Acetate co-polymer. Much softer and clearer than LDPE or LLDPE and has lower melt temperature. Its melt temperature goes down while its softness increases with increasing vinyl acetate (VA) content. EVA resins with 2-18% VA content are used for cast and blown packaging films.

EVOH
Ethylene-Vinyl Alcohol copolymer, used in coextruded plastic films to improve oxygen barrier properties. It is however a poor water vapor barrier. Even its otherwise excellent OTR (oxygen transmission rate) is sensitive to high humidity therefore, for packaging applications, it is usually the core layer of coextruded plastic films where it is shielded from moisture by protective layers of polyethylene. Its OTR also depends on its VOH (vinyl alcohol) content.

Foil
A thin gauge (0.000285 - 0.0005 inches / 6 - 12 microns) aluminum foil laminated to plastic films to provide maximum oxygen, aroma and water vapor barrier properties. Although it is by far the best barrier material, it is increasingly being replaced by metalized films because of cost.

Four Process Colors
The four process colors (cyan, magenta, yellow and black) are also referred to as CMYK However it is a myth that every image can be duplicated using the "four process colors." Additional 'spot' colors are often required to generate the high resolution images that are most preferred in modern packaging.

HDPE
High density (0.0004 - 0.004) polyethylene. Has much higher stiffness, higher temperature resistance and much better water vapor barrier properties than LDPE but it is considerably hazier.

Heatseal Layer
A heat-sealable innermost layer in plastic packaging films and laminates. Can be either adhesive laminated or extrusion coasted onto a non-sealable film (or foil).

Heatseal Strength
Strength of heatseal measured after the seal is cooled (not to be confused with "hot tack").

Hot Tack
Strength of heat seal measured before the seal is cooled which is very important for high speed packaging operations.

LDPE
Low density (0.0009 - 0.010) polyethylene. Used mainly for heat-sealability and bulk in packaging.

LLDPE
Linear low density polyethylene. Tougher than LDPE and has better heatseal strength but has higher haze.

MDPE
Medium density polyethylene. Has higher stiffness, higher melting point and better water vapor barrier properties.

MET-PET
Metalized PET film. It has all the good properties of PET film plus much improved oxygen and water vapor barrier properties however it is not transparent.

MET-OPP
Metalized OPP film. It has all the good properties of OPP film plus much improved oxygen and water vapor barrier properties (but not as good as MET-PET).

Monoaxial Orientation
Orientation of plastic films by stretching in one direction (machine or cross machine direction) only. These films are generally much stronger and stiffer but have very poor tear strength in the direction of orientation.

MVTR
Moisture vapor transmission rate usually measured at 100% relative humidity and expressed in grams/square meter/24hours (or grams/square inches/24hrs). See WVTR.

Mylar®
Mylar is a registered trademark of the Dupont-Teijin Corporation. It is the industrial brand name for that corporation's polyester (PET) film. Polyester film is a staple of multi-layer packaging for a wide variety of applications.

Nylon
Polyamide resins with very high melting points, excellent in clarity and stiffness. Two types are used for films: nylon-6 and nylon-66. The latter has much higher melt temperature thus better temperature resistance; but the former is easier to process and it is cheaper. Both have good oxygen and aroma barrier properties but they are poor barriers to water vapor. Nylon films can be cast (see CAN) or oriented (see BON).

Opacity
Hiding power of pigmented (mostly white) plastic films. It is beneficial for packaging materials sensitive to light (visible or ultraviolet).

OPP
Oriented PP (polypropylene) film. A stiff, high clarity film but not heat-sealable. Usually combined with other films such as LDPE for heat-sealability. Can be coated with PVDC (polyvinylidene chloride) or metalized for much improved barrier properties.

OPS Shrink Film
Oriented Polystyrene film. Very common alternative to PVC shrink films in Asia and Europe. Slightly higher priced than PVC films but more recyclable and has a greater shrink percentage.

OTR
Oxygen transmission rate. OTR of plastic materials varies considerably with humidity therefore it needs to be specified. Standard conditions of testing are 0, 60 or 100% relative humidity. Units are cubic centimeters (cc)/square meter/24 hour (or cc./100 square inches/24Hrs).

PP
Polypropylene. has much higher melting point thus better temperature resistance than PE. Two types of PP films are used for packaging: cast (see CAPP) and Oriented (see OPP).

PE
Polyethylene, depending on its density, it may be low density (see LLDPE); or medium density (see MDPE); or high density (see HDPE).

PET
Polyester (Polyethylene Terephtalate). Tough, temperature resistant polymer. Biaxially oriented PET film is used in laminates for packaging where it provides strength, stiffness and temperature resistance. It is usually combined with other films for heat sealability and improved barrier properties.

PET-G Shrink Films
Polyethylene Terephtalate Glycol shrink film. the most expensive shrink film for full body shrink sleeves, but clear, glossy, strong and most recyclable. the highest shrink percentage available is about 75% so this film is often required when the container has a narrow waist or neck.

Pinholing
The term for very small holes found in aluminum foil which dramatically affects MVTR (moisture vapor transmission rate) and OTR (oxygen transmission rate). Thicker foils have fewer pinholes.

PMS Number
The Pantone Matching System is the universally accepted color definition system. Colors can be blended or individually specified to match a specific Pantone reference color exactly.

PVC
Poly Vinyl Chloride. A tough, stiff, very clear film. The oriented version is used mainly for shrink film applications.

PVC Shrink Films
Polyvinyl chloride shrink film. Shrink percentages vary from about 40% for extruded PVC shrink tubing to over 60% for seamed material. The most cost effective shrink film for full body shrink sleeves.

PVDC
Polyvinylidene chloride. A very good oxygen and water vapor barrier but not extrudable therefore it is found primarily as a coating to improve barrier properties of other plastic films (such as OPP and PET) for packaging. PVDC coated and 'saran' coated are the same.

Release Coating
A coating applied to the non sealing side of cold sealable packaging films and laminates supplied in a roll form that will allow the packer to unwind these films or laminates on packaging machines.

Reverse Printing
The outermost layer is printed on the back side and laminated to the rest of the multi layer structure. While not mandatory in all industries, it is the preferred method of printing for the food industry as it guarantees there will be no ink contact with the food product.

Shrink Films
Oriented films that are not heat set after orientation. These films can shrink back close to their unstretched dimension at temperatures higher than the temperature of their orientation.

Single Web Stand-up Pouch
A stand up pouch is made from one piece of film. The front, gusset and back are continuous, so there is no seal at the gusset. Holds more weight than the Doy-style pouches so are commonly used for products weighing more than 500g.

Surface Print
The process whereby the ink is deposited directly onto the outermost surface of the packaging film or material. The process is most commonly used in short run printing. A UV (ultraviolet) coating may be added to provide a hard exterior finish that prevents the ink from flaking or chipping.

Trap Print
Another term for Reverse Printing. Trap printing derives its name from the fact that the ink is trapped between the outer layer of material and the substrate.

WVTR
Water vapor transmission rate usually measured at 100% relative humidity, expressed in grams/ square meter/24 Hours (or grams/100 square inches/24Hrs). See MVTR

ZipSeal™ Bag
A reclosable or resealable pouch produced with a plastic track in which two plastic components interlock to provide a mechanism that allows for reclosability in a flexible package.

 

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