Glossary


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

A

  • ADHERE - To bond; to cause two surfaces to be held together by adhesion.
  • ADHESION - Level of attraction between a coating and the surface it is bonded with. Surface energy of the material determines the strength of the attraction.
  • ANCHORAGE - A term for how well a coating sticks to the substrate. Poor anchorage can cause coating to easily rub off the substrate.
  • ANTI-BLOCK - An additive which prevents blocking (see Anti-stat).
  • ANTI-STAT - An additive which reduces the static electricity present in most finished plastic goods (caused by friction generated during processing). This 'static' is most apparent in very thin films - particularly HDPE.
  • AUTOCLAVE - Suitable for the safeguarding and sterilisation of surgical/dental instruments and workwear.  Convenience of use combined with seal integrity and security helps ensure that items are properly sterilised before use.

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B

  • BACKING ROLLER - A roller that is used to hold the web against another roller.
  • BAG RELEASE TAPE – General name given to the silicone coated release tapes used in the manufacture of courier / mailing bags, money bags etc. These bags often have a strip or strips of adhesive for sealing the bag shut when it has been filled. The bag release tape protects the adhesive strip until it is used. The release tape is then peeled off and the bag is sealed shut.
  • BIODEGRADABLE - A material that is broken down by bacteria or other organisms and absorbed into the eco-system without compromising it.
  • BLOCKING - A condition affecting mainly LDPE and LLDPE bags, where 2 layers of film stick to each other, making the bag difficult (or in extreme cases, impossible) to open. Bags in this state are 'blocked'.
  • BOBBINS - Also referred to as spools. It is where a material, such as film is wound laterally across the width of a core or bobbin, as well as around it. A well-known example of this is sewing machine thread. This process enables the converter to put extremely long lengths of custom slit material on one roll which means less roll changes and cost savings on a manufacturing line.
  • BUTT SPLICE - A splice made by joining two pieces of substrate end-to-end without a space nor any overlapping. An adhesive tape centred on both sides is usually used to make the splice.

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C

  • CAST FILMS – Polyolefin film, usually polypropylene, which is not oriented (stretched) after it is extruded.
  • CAST POLYPROPYLENE – Polyolefin film, usually polypropylene, which is not oriented (stretched) after it is extruded.
  • CATALYST - Any material which induces a chemical reaction, without undergoing any physical change itself.
  • CALIPER - Thickness measurement of material expressed in thousandth of an inch (mils), microns or millimetres.
  • CENTRE FOLD SHEET(ING) [CFS] - The same as 'lay flat tubing' but with a slit on 1 edge.
  • COATER - A machine that coats chemicals onto a substrate. Generally consists of a coating head, a drying oven / curing unit, and unwind / rewind stations for the substrates. It may also include stations for other functions such as corona treatment or surface priming.
  • COATING - The thin layer of material which is deposited onto the film substrate.
  • COATING WEIGHT / COAT WEIGHT – This is a measure of the weight of coating per unit area. In SI-units expressed as grams per square metre (g/m2).
  • COMPOSTABLE - A material which will fully degrade in the specific conditions of a compost heap with the presence of certain defined chemicals and/or microbes.
  • CONVERSION, CONVERTING- Related to the operation of making any change to a substrate, such as coating, slitting, spooling, edge trimming, sheeting, printing, perforating, laminating and so on.
  • CORE - A cardboard, resin impregnated cardboard or plastic tube around which a roll of film is wound.
  • CORE PLUG - A plastic plug which is fitted into the ends of a core to retain an end plate and packaging material.
  • CORONA TREATMENT – This is a form of treatment for films and papers to improve anchorage. The web is treated with a high voltage arc that creates an oxidized layer. This allows the coating to bond to the film better than to the untreated surface.
  • CORONA DISCHARGE TREATMENT – The film is passed through a device which changes the surface resistivity of the film (effectively scuffing the film electrically), so that ink, adhesives etc. can be applied to the film more easily.
  • CPP – Polyolefin film, usually polypropylene, which is not oriented (stretched) after it is extruded.
  • CRATER - Coating defect where a circular void opens up in the coating on a release liner.
  • CROSS DIRECTION - When referring to roll, sheet or web, "cross direction" is at right angles to the direction the web runs through a machine. This is also known as “Transverse Direction”.
  • CROSS LINKER - An additive that will cause polymer molecules to inter-connect, effectively increasing the molecular weight of the polymer.
  • CROSS-LINKING - Developing a three-dimensional molecular structure in a coating normally activated by heat or irradiation.
  • CURE / CURING - In U.V. systems, it refers to photo-polymerisation. It is the hardening of the coating by means of chemical reaction which occurs after exposure to UV light.

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D

  • DEGRADABILITY - Ability of materials to break down, by bacterial (biodegradable) or ultraviolet (photodegradable) action.
  • DENSITY - The mass per unit volume of a substance under specified conditions of pressure and temperature.

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E

  • EDGE-TRIMMED - The edges of single wound or double wound sheet film are slit by fixed blades so that the width of the film is accurate to 2mm. This is more expensive than standard film because of the wasted trim and should only be specified when accurate width is essential.
  • ELECTROMAGNETIC SPECTRUM - The entire range of radiant energy. Ultraviolet light lies to the left of the visible region.
  • ELECTROSTATIC CHARGE – This is an (static) electrical charge which builds up on a film due to its high dielectric strength. It can be caused by rubbing of film against itself or against another non-metallic surface. It can also be caused as the film is unwound, as the layers of film are separated. This charge can be either negative or positive.
  • ELONGATION - The distance a film will stretch in the machine or cross direction before breaking under controlled conditions, expressed as a percentage of original length. Elongation is not necessarily an indication of conformability.
  • EMBOSSED - A series of small indentations in the film give a cosmetic effect.

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F

  • FACESTOCK - In label printing, the facestock refers to the material, such as paper or film that is used for the top layer of the label. This is the layer that is adhered to another surface.
  • FOCAL LENGTH - The distance from the lamp reflector to the focal point.
  • FOCAL POINT - A U.V. lamp reflects and focuses the radiant energy into a point. The focal point should be at the substrate surface when UV coating.
  • FREE RADICAL - An atom or group of atoms that has at least one unpaired electron and is therefore unstable and highly reactive. They are formed when a photo-initiator absorbs U.V. light during a UV coating process.

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G

  • GRAVURE COATING - Coating using a gravure roller. A gravure roller has a surface covered with a pattern of cells or grooves that meter the coating to the web after a doctor blade wipes off the excess.
  • GAUGE - A measure of the thickness of films: 100 gauge = 1.0 mil = 25.4 micrometers (micron).
  • GAUGE BAND - A variation in the thickness of a roll of film usually in (or nearly in) the machine direction, observed as a thinner band in the roll.
  • GRAMS/SQUARE METRE OF COATING – A metric measure of the amount of dry coating applied to a surface.

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H

  • HAZE - The amount of light, which is transmitted through or reflected from a film.
  • HEAT SEAL - An adhesive film intended to be reactivated by the application of physical or chemical changes caused by exposure to high temperatures.
  • HOT MELT (THERMOPLASTIC) – A type of adhesive that is solid at room temperature, but flows when heated.
  • HIGH DENSITY POLYETHYLENE (HDPE) - A polyethylene thermoplastic made from petroleum that has a density of greater or equal to 0.941 g/cm3.
  • HIGH SLIP (HDPE) - An additive which makes film more slippery (desirable in some applications, undesirable in others)

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I

  • I.D. - Inside diameter.

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J

  • J FOLD SHEETING (JFS) - Similar to centre fold sheeting, but slit at a point not on the edge - mainly used for making side weld bags with a lip.

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L

  • LABEL STOCK - Materials in roll or sheet form with liner, which can be later printed, frequently die cut, and intended for use as labels.
  • LAMINATE – The act of bringing two or more layers together to create a multi-layer construction, such as release liner-adhesive-paper. This is generally done at the rewind station of a coater. Can also refer to the construction made by this process, containing layers of substrates and adhesive(s).
  • LAPPING – A material, such as film is wound laterally across the width of a core or bobbin, as well as around it. A well-known example of this is sewing machine thread. This process enables the converter to put extremely long lengths of custom slit material on one roll which means less roll changes and cost savings on a manufacturing line.
  • LAYFLAT TUBING(LFT) – A tube of material which is squashed flat and wound on to a reel.
  • LINE SPEED - The rate of travel of the substrate through a machine, usually expressed in metres per minute.
  • LOW DENSITY POLYETHYLENE (LDPE) - A polyethylene thermoplastic made from petroleum that has a typical density range of 0.910 - 0.940 g/cm³.

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M

  • MACHINE DIRECTION - Strength properties are usually different across the width of a paper or film compared to the length, so it is important to be able to differentiate between the manufactured directions of the substrate. When referring to roll, sheet or web, "machine direction" is parallel to the direction which it runs through the machine it was produced on.
  • MEDIUM DENSITY POLYETHYLENE (MDPE) - A polyethylene thermoplastic made from petroleum that has a typical density range of 0.926 - 0.940 g/cm³.
  • METALLIZE – The act of coating a surface by vacuum evaporation, usually with aluminium.
  • METALOCENES – A fairly new member of the polythene family - excellent clarity and strength, but difficult to extrude and process.
  • MICRON - A linear measurement, 1/1000 of 1mm (0.001mm).
  • MICROPERFORATED - A series of tiny holes in the film, making it pervious to air and other gases.
  • MIL – Imperial unit of measurement for the thickness of a substrate. A unit of length equal to one thousandth of an inch. Converting mils to metric units equate one mil to 25.4 microns or 0.0254mm. However, caution should be taken with the accuracy, as the number of mils is often a rounded figure rather than an exact figure.
  • MOISTURE VAPOUR TRANSMISSION RATE - A measure of the rate of water vapour transmission through a film, usually measured in grams / square meter / 24 hours.

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N

  • NIP - The point where two rollers come together.

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O

  • O.D. - Outside Diameter.
  • ORANGE PEEL - Coating defect that resembles the dimples on the surface of an orange, caused by the coating film failing to flow out to a perfectly smooth surface.
  • ORIENTED POLYPROPYLENE (OPP) - A flexible thermoplastic film derived from melting, orienting and stretching polypropylene polymer. It can be stretched in 1 direction or 2 directions, which give it different properties.
  • OUT-GASSING - The release of volatile components under heat or vacuum.
  • OXY-DEGRADABLE FILM - Plastics that have an additive to help degradation within a realistic time scale. The film can be extruded with a small amount of an additive that does not affect the performance, until it is triggered by UVA & UVB light sources. The additive then acts as a catalyst to help the degradation process.

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P

  • PANCAKE WOUND - The typical form of a roll of tape or film where each layer is directly on top of the next one.
  • PEEL STRENGTH - A measure of the force to pull a strip of tape off of a substrate. The test is usually done at a 90 or 180 degree angle. Results are in units of force per unit width (typically g/25mm, cN/inch or N/cm).
  • PERFORATING (HOT NEEDLE) - A series of tiny holes in the film, making it pervious to air and other gases.
  • PHOTOINITIATOR - The chemical substance that absorbs U.V. light and by the formation of free radicals initiates the polymerisation of the coating.
  • POLYESTER (PET) - Polyethylene Terephthalate (polyester) thermoplastic film, which has excellent optical clarity, smoothness and processing performance.
  • POLYETHYLENE (PE) - Called “Polythene” in the U.K. A thermoplastic made from ethene through polymerization. Mechanical properties of PE depend significantly on variables such as the extent and type of branching, the crystal structure, and the molecular weight.
  • POLYMER – A large molecule composed of mostly or completely from a large number of smaller, identical molecules (called monomers) linked together.
  • POLYPROPYLENE (PP) - A thermoplastic polymer with a level of crystallinity typically between that of Low Density Polyethylene (LDPE) and High Density Polyethylene (HDPE).
  • POST CURE - U.V. coatings can continue to react for a period of time after exposure to U.V. light, until a point when all possible cross-linking has been done.
  • PRESSURE SENSITIVE - A term used to describe a category of adhesive tapes and adhesives (PSA’s) which, when dried (solvent / water free) are aggressively and permanently tacky at room temperature. They firmly adhere to a surface upon contact with little pressure applied. These products require no activation by heat, water, or added solvents in order to exert a strong adhesive holding force to the surface to which they have been applied. Despite their aggressive tackiness, they have sufficient cohesive holding power and elastic nature so that they can be handled with the fingers and removed from smooth surfaces without leaving a residue.

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R

  • RECYCLED - A processed plastic which has been used for its intended purpose and subsequently reworked.
  • RELEASE FORCE - The measure of the force required to separate a unit width of pressure sensitive tape from a release coated surface at a controlled angle and speed.
  • REPROCESSED - A processed plastic which has not been used (e.g. factory waste) and subsequently reworked.
  • REWINDING - The operation of winding the web from the reel onto a core to produce rolls of the desired length, diameter, and tension.
  • REWIND SLITTING - The method is for producing multiple cuts per cycle. This has a longer set-up time than log slitting. The process actually rewinds the web across a set of pre-spaced knives and spacers, onto a rewind shaft that is set with pre-slit cores and spacers, with each individual slit roll wound onto separate cores.
  • ROLL COATING - A system of coating that uses a combination of 2 or more rollers to meter and apply the coating to the web. Rollers may be polished or rubber coated. Metering is adjusted by changing variables, such as nip gap, roll speed and line speed. If the applicator moves in the web direction, it is called a "direct roll". If it moves opposite the web, it is called a "reverse roll". A common configuration is a 3 roll reverse coater, with a pick-up roll in the adhesive pan, a metering roll, and an applicator roll. There is also a backing roller to hold the web at the nip.

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S

  • S1S - Silicone one side. Coating is on only one side of the material.
  • S2S - Silicone two sides. Coating is on both sides of the material.
  • SILICONE – Any of a number of polymers containing alternate silicon and oxygen atoms, with organic groups attached to the silicon atoms. Their properties vary depending on the organic groups. They are fluid, resinous, rubbery, extremely stable in high temperatures, and water-repellent.
  • SILICONE COATING - A type of coating often used on a release sheet.
  • SILICONE RELEASE COATING - Thin coating of material applied to a paper or film to produce a silicone release liner. The coating enables a tacky substance or adhesive coated facestock to be wound up or stacked in sheets for safe transport until required to be used.
  • SILICONE RELEASE LINER– Paper or film with a release coating for carrying the adhesive or tacky facestock material; also called “backing”. This is generally peeled off and discarded when the facestock is used.
  • SINGLE WOUND SHEETING (SWS)– A single layer of film wound on to a reel - made by slitting layflat tubing on both edges and winding on to 2 reels.
  • SLITTING - The process of cutting a large roll of film to several shorter or narrower rolls.
  • SPOOLER – A machine that winds narrow width products across and around a core or bobbin (see TRAVERSE WOUND).
  • SPOOL WOUND – See Traverse Wound.
  • SPOOL OR SPOOLING – A material, such as film is wound laterally across the width of a core or bobbin, as well as around it. A well-known example of this is sewing machine thread. This process enables the converter to put extremely long lengths of custom slit material on one roll which means less roll changes and cost savings on a manufacturing line.
  • SPREADER ROLLER - A roller used on film converting equipment which prevents a thin film from wrinkling or creasing.
  • SUBSEQUENT ADHESION - The force required to remove a unit width of pressure sensitive face-stock from an uncoated film after it has been in contact with a release liner for a given period of time. This must be compared with the adhesion of the same tape that has not been in contact with the release liner to determine the degree of loss of adhesion.
  • SUBSTRATE - The product (usually film or paper) upon which a coating or ink is printed.
  • SURFACE ENERGY – All substrates have a surface energy value. These are measured in dynes. The lower the dyne value the more difficult it is for a coating to stick to or wet out on the substrate.
  • SURFACE TREATING - Any method of treating (such as chemical, flame, and corona) a substrate so as to alter the surface and render it receptive to inks, paints, lacquers, and adhesives.

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T

  • TEAR RESISTANCE - The force required to propagate a tear in a substrate in a given direction after the tear has been initiated.
  • TELESCOPING - A sideways sliding of the layers in a roll, one over another, such that the roll looks like a funnel or a telescope, often over a period of time. This can cause scratches in the film.
  • TENSILE STRENGTH - The force required to break a unit width of a substrate by pulling on opposite ends of the piece.
  • THERMOPLASTIC - Substances (esp. synthetic resins) that become plastic on heating and harden on cooling. Films such as Polyethylene, Polypropylene and Polyester are classed as thermoplastic films.
  • TOLL COATING - Coating of a Customers own material. (see Silicone Release Coating)
  • TRANSVERSE DIRECTION - See Cross Direction.
  • TRAVERSE WOUND - Also referred to as spool wound. It is where a material, such as film is wound laterally across the width of a core or bobbin, as well as around it. A well-known example of this is sewing machine thread. This process enables the converter to put extremely long lengths of custom slit material on one roll which means less roll changes and cost savings on a manufacturing line.
  • TREATMENT/TREATED - see corona discharge treatment

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U

  • ULTRAVIOLET LIGHT - Part of the electromagnetic spectrum. The 190 to 260-nm wavelength region of the U.V. spectrum is the portion used to cure U.V. silicones.
  • UNWIND / REWIND - Stations at either end of the coating or slitting machine that hold the rolls of product used or made. The unwind stations hold the rolls to be used and feed them to the machine. The rewind station winds up the material after processing.
  • UNIFORMITY – Consistency in the properties of a coating along and across a piece of film.
  • UV CURED COATING - A coating which is reacted or polymerized through the action of ultraviolet light rather than heat.
  • UV Stabiliser - An additive which reduces the tendency of plastic materials to photodegrade as a result of ultraviolet rays (i.e. sunlight).

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W

  • WATER PENETRATION RATE (WPR) - The weight of water which passes through a known area of film under a specified time and conditions.
  • WATER VAPOUR TRANSMISSION – This is defined as the weight of water vapour which passes through a known area of film, within a specified time and conditions.
  • WEB - The general term for a material that is fed through a coater in a continuous sheet.
  • WINDING DIRECTION – When a roll is wound up, a term for the side of the film where the required surface (such as a coating) is. It can be described as either "INSIDE" or "OUTSIDE" wound.
  • WINDOW PATCHING FILMS – PET (Polyethylene Terephthalate) films are ideally suited for carton windows. The surface of these films are corona treated and offer excellent adhesion to typical adhesives used in this industry. Window patching PET’s are 100% recyclable and are available in a variety of thicknesses with or without anti-fog. Films are used for cartons that may contain Sandwiches, cakes and other food and non-food stuffs.

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