Glossary of Polythene Packaging Terminology

The blown polythene film industry like every other industry has its own terminology. The following glossary is a list of terms commonly used in the packaging industry and particularly by Hanmere.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Glossary

A

Anti-stat
Anti-static additive or film containing an anti-static additive that aids the dissipation of static electrical charges. Typically used in films where the is a lot of potentially explosive dust in the environment. Such films are not always suitable for food contact use due to the migration of the additive.

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B

Bags on a roll
Continuous roll of seamless tubing perforated under bottom seal. Bags must be torn off to open. See also Tear Off On Roll.
Barcode
An optical, machine-readable, representation of data; the data usually describes something about the object that carries the barcode. For further information on unique globally recognised barcodes refer to the GS1 UK® Website. Refer Solutions > Barcoding.
Bleed
Where the printing on a piece goes all the way to the edge of the plastic accomplished by printing beyond the margins of the piece and then trimming to the margin.
Blown Film
Plastic film produced from polymers, such as polyethylene, by the blown film process. In this process, the molten polymer is extruded through a circular die into a tube. This tube is expanded (“blown”) by internal air pressure into a larger bubble with a much reduced wall thickness and cooled with external air quenching and possibly internal bubble cooling.
Bottom seal bags
Individually bags formed from continuous tubing, sealed on the bottom. They can be flat or side gusseted bags with a seal at the bottom; usually with a skirt. They can be presented as cut bags in packs or boxes or as bags on a roll.

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C

Centre Fold Sheet (CFS)
Film that is presented folded longitudinally down the middle. Can be referred to as sheet/sheeting: continuous lengths of film, or Sheets: discrete cut or Tear Off On Roll pieces. Designated by two or three dimensions. Sheeting: Face Width / Open Width, Sheets: Face Width / Open Width x Length
CFS
See Centre Fold Sheet
Clarity
Transparency of the film based upon surface gloss and haze.
Co-extrusion
Extrusion using two or more extruders feeding a single extrusion die. The output of the extruders is combined in a die, the material from each one forms a distinct layer in the final film. See Tri-Ex and Hankraft.
Colour
A coloured film whose colour density/opacity is greater than a Tint film but less than an Opaque film.
Co-polymer
Result of two monomers being combined through polymerisation.
Core
A paper or plastic tube on which film is wound.
Core Bung
Plastic inserts placed in the open ends of cores in order to reduce the risk of the cores becoming crushed or damaged during transit and storage. Particularly so for rolls of finished product.
Corrugated Cardboard
A durable, lightweight material made from kraft paper. Corrugated cardboard has an arched layer, called fluting, between smooth sheets, called liners. The corrugated cardboard most commonly used to make cases has one layer of fluting between two smooth sheets. For stronger board two fluted layers are used with a smoother intermediate later.
Corrugated Case
A box made from corrugated cardboard.

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D

DIBG
see Dip In Bottom Gusset bag.
Die
The device which material is extruded to give its shape. In the case of blown film extrusion the die has a circular slot and thus the polymer exits as a tube.
Dip In Bottom Gusset Bags
A gusseted bag with a single gusset in the bottom and side welds rather than a bottom weld.
Double Wound Sheet
A double layer of film wound onto a core. Can be referred to as sheeting: continuous lengths of film, or sheets: discrete cut or Tear Off On Roll pieces. Designated by one or two dimensions. Sheeting: Full Width, Sheets: Full Width x Length
Dwell time
The time usually expressed in seconds at a given temperature that is required for the application of heat to heat seal a material.
DWS
See Double Wound Sheet.

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E

Elasticity
The ability of plastic to rebound back to its original state after being stretched.
Elongation
The ability of plastic to be stretched without breaking.
Extruder
A machine that makes product by means of extrusion. Typically an extruder consists of a large steel barrel surrounded by heaters, which melt the polymer granules. Inside of the barrel is a large feed screw which forces the liquid plastic under pressure through a die to be made into plastic forms by either the cast or blown processes.
Extrusion
A product formed by extruding material through a die, or the process of extruding a material.

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F

Face Width
The finished width of a product. In the case of a gusseted bags this is the width of the bag with the gussets folded in.
FCM
See Food Contact Material.
Food Contact Material (FCM)
Food contact materials are all materials and articles intended to come into contact with food, such as packaging and containers, kitchen equipment, cutlery and dishes. These can be made from a variety of materials including plastics, rubber, paper and metal. For further information refer to the European Food Safety Authority website
Flat Bag
A bottom seal bag or side weld bag with no gussets. Designated with two dimensions: Face Width x Bag Length
Full Width
The width of the tube used to manufacture the product. In the case of a gusseted bag this is the width with the gussets folded out, and in the case of a flat bag the full width is identical to the face width.

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G

Gauge
A term used when referring to the thickness of a sheet or film material. The higher the gauge, the thicker the material. Here are some examples and equivalents:

1 gauge : 1/100 mil
80 gauge : 8/10 mil
100 gauge : 1 mil
1 mil : 1/1000 inch
1 inch : 25.4 mm
1 mircon : 0.001 mm
Gauge band
Thickness irregularity in films.
GCFS
See Gusseted Centre fold Sheet
GLFT
See Gusseted Layflat Tube
GS69
Hanmere’s trade name for its blended single layer film. Refer “Solutions > Product Range“.
Gusset
The fold in the side or bottom of a bag, allowing it to expand when contents are inserted.
Gusseted Bag
A style bag with both sides tucked in to form gussets. Designated with three dimensions: Face Width x Full Width x Bag Length
Gusseted Centre Fold Sheet (GCFS)
Film that is presented folded longitudinally down the middle and with gussets in both sides. Can be referred to as sheet/sheeting: continuous lengths of film, or Sheets: discrete cut or Tear Off On Roll pieces. Designated by three or four dimensions. Sheeting: Face Width x Full Width / Open Width, Sheets: Face Width x Full Width / Open Width x Length
Gusseted Layflat Tube (GLFT)
Film that is presented in flattened tube form with gussets in both sides and without any end seals. Can be referred to as tube: continuous lengths of film, or tubes/sleeves: discrete cut or Tear Off On Roll pieces. Designated by two or three dimensions. Tubing: Face Width x Full Width, Tubes/Sleeves: Face Width x Full Width x Length

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H

Hankraft
Hanmere’s proprietary co-extruded paper replacement film, that has the external appearance and texture of kraft paper. Refer “Solutions > Product Range” and “Solutions > Paper Replacement
HDPE
See High Density Polyethylene.
High Density Polyethylene (HDPE)
HDPE is defined by a density range of 0.93-0.97 g/cm3. It is not reactive at room temperatures, except by strong oxidising agents, and some solvents cause swelling. Although the density of HDPE is only marginally higher than that of LDPE, HDPE has little branching, giving it stronger inter-molecular forces and tensile strength than LDPE. The difference in strength exceeds the difference in density, giving HDPE a higher specific strength. It is also harder and more opaque and can withstand somewhat higher temperatures (120 °C/ 248 °F for short periods).

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I

IBC
IBC may refer to Internal Bubble Cooling or Intermediate Bulk Container
Internal Bubble Cooling (IBC)
A process where there is forced movement by cool air in the blown film extrusion bubble whilst maintaining a constant pressure. For IBC to function cold air is forced into the bubble at the same time as hot air sucked out of the bubble.

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L

Layflat Tube (LFT)
Film that is presented in flattened tube form with out gussets and without any end seals. Can be referred to as tube: continuous lengths of film, or tubes/sleeves: discrete cut or Tear Off On Roll pieces. Designated by one or two dimensions. Tubing: Full Width, Tubes/Sleeves: Full Width x Length
LDPE
See Low Density Polyethylene.
LFT
See Layflat Tube
Linear Low Density Polyethylene
LLDPE is defined by a density range of 0.910–0.940 g/cm3. It is not reactive at room temperatures, except by strong oxidising agents, and some solvents cause swelling. LLDPE film has higher tensile strength and higher impact and puncture resistance than the LDPE.
LLDPE
See Linear Low Density Polyethylene
Low Density Polythene (LDPE)
LDPE is defined by a density range of 0.910–0.940 g/cm3. It is not reactive at room temperatures, except by strong oxidising agents, and some solvents cause swelling. It can withstand temperatures of 80 °C continuously and 95 °C for a short time. Made in translucent or opaque variations, it is quite flexible and tough. This resin has good clarity but weak film strength. Primarily for food and utility bags

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M

MDPE
See Medium Density Polyethylene.
Medium Density Polythene (MDPE)
MDPE is defined by a density range of 926–0.940 g/cm3. MDPE has good shock and drop resistance properties. It also is less notch sensitive than High Density Polyethylene. Stress cracking resistance is better than that of HDPE. MDPE is typically used in gas pipes and fittings, sacks, shrink film, packaging film, carrier bags, and screw closures
Micron
Thickness of material: 1 micron = one millionth of a metre.
Migration
Migration is the transfer of chemical contaminants from food contact materials into food.
Mil
Thickness of material. 1 mil = on thousandth of an inch.

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O

Opacity
Hiding power of pigmented plastic films. It is beneficial for packing materials sensitive to light (visible or ultraviolet).
Opaque
A high opacity film that is relatively impervious to light.
Open Width
The width of folded sheet material with all the folds opened.

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P

Perforations
The practice of creating holes in a product for venting purposes or a long series of holes so that plastic film can be torn more easily.
Polyethylene
A simple thermoplastic polymer of ethylene. Highly puncture and tear resistant. Not affected by extreme temperatures. Depending on its density, it may be low density (see LDPE). medium density (see MDPE). or high density (see HDPE).
Polymer
A material made through the process of polymerisation.
Polymerisation
The process by which a gas heated under pressure forms a solid.

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S

Sack
A large flat or gusseted bag in a heavy gauge (>100µm) used for transporting and storing goods.
Seal
Term used to describe the permanent welding of the film to from a closure or the closure itself.
Seal strength
Measurement of force required to break or destroy a heat seal.
Side weld
Bags formed by sealing the sides rather than the bottom. The typical method of forming Dip in Bottom Gusset (DIBG) bags.
Single Wound Sheet
A single layer of film wound onto a core. Can be referred to as sheeting: continuous lengths of film, or sheets: discrete cut or Tear Off On Roll pieces. Designated by one or two dimensions. Sheeting: Full Width, Sheets: Full Width x Length
Skirt
The short piece of film between the seal and the cut end of a bag.
Slitting
The cutting of a wide master roll into several narrower rolls.
Slit-sealing
The cutting and sealing of a wide tube to form several narrower tubes.
Static
An electrical charge built-up in plastic film.
SWS
See Single Wound Sheet.

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T

Tear Off On Roll (TOOR)
A conversion method where by discrete products are presented in a continuous strip wound on a roll and separated by tear-off perforations.
Tear resistance
The ability of a film to resist the propagation of a tear.
Tensile strength
The force required to break through film and bags, or snap rope, cable ties, and wire by pulling on opposite ends. Determined by material thickness and width.
Tint
A coloured film with a very low opacity
Tolerance
Allowable deviation from a nominal or specified dimension. Minimum/maximum range of measurement.
TOOR
See Tear Off On Roll
Transmission Rate
The quantity of moisture and/or gas passing through the film over a specific period of time for a given humidity and an temperature.
Tri-Ex
Hanmere’s brand name for its standard co-extruded film.

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