* General comments regarding this Glossary This Glossary has developed over time and has been started in part in the mid 1990's. We were not able to track all information back to its original source, which also does not allow us to identify the origin of all industry terms. The majority of the terms have been described by Loparex employees. Some parts of this glossary have been mixed together with explanations originated on www.wikipedi.org. In general this glossary is intended for our customers to explain general industry terms. Any copying for commercial use is not allowed! Please refer to our disclaimer for further information. Thank you for visiting www.loparex.com
3 Roll coating / Offset Gravure coating Offset Gravure coating is a coating method consisting of 3 roller and typically an enclosed doctor blade. The first roller is a gravure roller with a defined gravure shape and depth. On this roller the doctor blade is mounted to apply solvent based, water based or 100% solid coating materials. The second roller is a rubber based application roller which picks up the coating material from the gravure roller and transfers it over to the web, which is pushed by the third roller against the rubber roller.
5 Roll Coating / Multi Roll Coating / Smooth Roll Coating The five smooth roll coating method is a standard coating method in the release liner industry. It consist of three steel and two rubber rollers, which run at different speeds and reduce the initial coat weight based on different roller surface speeds.
6 Roll Coating / Multi Roll Coating / Smooth Roll Coating The 6 roll coating process is similar to the 5 roll coating process, however the sixth roll allows to reduce the coat weight even further and therefor this coating head is better suited for filmic surfaces and the application of coat weights well below 1 micron.
Accelerated Aging Subjecting material to far more severe conditions than are likely to be encountered normally in order to predict behavior during natural long-term aging in a much shorter time frame.
Accelerator A accelerator is a material added to a liquid composition to convert the mass into a solid or speed up its cure.
Adhesion Promoter A coating which is applied to the substrate which improves the adhesion of another material. Adhesion promoters can also be tie layers between two plastic layers or a plastic layer and another substrate, as well as liquids adhesion promoters which are added into coatings for improved anchorage, typically then referred to as anchorage additive.
Adhesive An adhesive is a material, usually in a liquid or semi-liquid state, that adheres to surfaces or bonds items together. Adhesives come from either natural or synthetic sources. The types of materials that can be bonded are vast but adhesives are especially useful for bonding thin materials. Adhesives cure or harden by either evaporating a solvent or by chemical reactions that occur between two or more constituents. In the release liner industry adhesives can be used to simply hold a label in place or as resins to build airplane body's and wings in composite materials. In general the release liner industry faces thousands of differently compounded adhesive type materials.
Adhesive Ooze (Bleed) Adhesive Ooze is the exudation of an adhesive from label stock or labels as a result of adhesive flow (promoted by high temperature or pressure). This is often seen as a discoloration of a paper face stock or as a sticky substance on the side of a roll material.
Age Down Age Down describes a phenomenon where release values decrease with time of aging. This is sometimes found when solvent-based adhesives are applied to release liners.
Age Resistance Age resistance is on one side the resistance to deterioration of a "product" by external influences like oxygen, heat, humidity, pressure or light, and on the other side resistance to internal chemical reaction or interaction with the material itself or with other externally chemicals in the environment. The aging of a material can be influenced by the right packaging and appropriate storage conditions.
Age Up Age up describes a phenomenon where release values increase with time. This has been explained as resulting from increasing association of the adhesive with the release composition due to adhesive flow and/or chemical reaction or interaction between the adhesive and excess silicone hydride cross-linker, and/or silicone post cure around the adhesive. In general adhesive age up is part of unstable release performance issues.
Aging The passage of time when a material may undergo changes due to internal chemical or physical changes or through exposure to radiation, temperature, humidity, gases and liquids.
Aging of Adhesives Aging of adhesives can also occur over longer periods of times like week or months. Typically the release values of a laminate between an adhesive like material and the release liner will be affected by this process.
Aging of Silicones In the release liner industry aging typically describes the fact, that e.g. addition cured silicones continue to finish off the internal network reactions after they have already be cured on the coating line. This aging typically takes 4 - 48 hours and happens while the material is still in the release liner manufacturers’ plant.
Air Knife An air knife is a tool used to blow off liquids or debris from products as they travel on a web. The knife consists of a high intensity, uniform sheet of laminar airflow sometimes known as streamline flow. An industrial air knife is a pressurized air plenum containing continuous slots through which pressurized air exits in a laminar flow pattern. The exit air velocity then creates an impact air velocity onto the surface of whatever object the air is directed. This impact air velocity can range from a gentle breeze to greater than Mach 0.6 (40,000 ft/min) to change the coating surface of a product without mechanical contact. Air knives remove liquids, control the thickness of liquids, dry the liquid coatings, cool product surfaces or create a hold down force to assist in the mechanical bonding of materials to the surface. Electrical currents from anti-static bars can also be injected into the exit air knife stream to neutralize the static electricity charge on some surfaces.
Air Permeability The air permeability is a property of a substrate, in our case typically of a paper web, which tells us something about the porosity of the paper itself. The air permeability can be measured by blowing air thru the paper and measure the drop in air pressure.
Anchorage Anchorage is a term used in the release liner industry to describe the attachment of a release coating to a converted web like a release liner. Anchorage is measured as rub-off and typically rated on a scale from 1 to 6, whereas 1 means the anchorage is perfect and the release coating is fully anchored to the substrate and a rating of 6 means that the release coating could not hold on to the substrate and can be removed with minimum force applied. Anchorage issues can cause serious issues in downstream converting processes and Loparex makes sure that only release liner with perfect anchorage leave the factory. However sometimes long term chemical reactions can influence the anchorage even long after coating and cause delayed anchorage issues, which Loparex's experienced staff is also trying to avoid.
Anilox Roller This is what makes Flexo printing or coating unique. The Anilox Roller meters the ink or coating that is transferred for uniform thickness. It has engraved cells that carry a certain capacity of the coating which are so small that they can only be seen with a microscope.
Annealing A process of holding a material at a temperature near, but below, its melting point. The objective is to permit stress relaxation without distortion of the dimensions. It is used on blown film and oriented film stock like MOPP or BOPP. Loparex has the capability to orient its blown films.
Anti-Oxidants Primary and secondary anti-oxidants are additives which are added into plastic resin to stabilize the resin at high processing temperatures.
Anti-Static / web discharge During processing of web like materials over rollers, static charge will build up. Especially with siliconized materials, which are isolators, the static buildup can be severe and reach several tens of thousands or over 100 000 Volts. A continuous static discharge of the web is a must during release liner processing. However it is known that certain types of electric discharge can lead like the static charge itself to unwanted effects on the release forces of a release liner.
Backing of a Laminate The backing of a laminate is the release liner. The release liner functions as protection during storage, processing and transportation for the pressure-sensitive adhesive. The backing is separated from the adhesive prior to application to end product.
Bagginess / Baggyness Bagginess is similar to a floppy edge, just that the low tension area is in the center of the web. Bagginess can be seen on paper and film substrates and can cause severe converting issues. Loparex is trying to avoid issues like bagginess or floppy edges by carefully screening raw materials and processes.
Base Weight The base weight of a substrate is the measured weight of a defined area of the same material. It is typically defined as "grams per square meter" [gsm] or as English pounds (454.4 grams) per (long)ream [#/ream] of material. Conversion factor: 1.0 #/ream = 1.6275 gsm
Bleed The migration of plasticizers from an adhesive film into the face stock or face stock into the adhesive. Edge ooze of adhesives is also sometimes referred to as bleed.
Blistering Blistering can occur when a poly coated paper web is heated too much in the thermal oven for silicone coating. The water which evaporates from the paper fiber in the web will push thru the poly coated surface, if the poly coat has been heated too much and gets soft. A blistered surface feels like goose bumps on the human skin. Blistering will make a release liner unusable due to its effect on the release force.
Blocking Blocking occurs when a silicone coating was not fully cured during the coating process and was wound up "wet" into the roll. The curing process will continue in the roll and bond two layers in the roll together. Depending on the amount of silicone which was uncured, the blocking can be light and only causes a slight sound, when rewinding the roll or it can be so strong that two layers of the roll cannot be separated, without damaging the substrate.
Blown Film Extrusion This process is the same as a regular extrusion process up until the die. The die is an upright cylinder with a circular opening similar to a pipe die. The diameter can be a few centimeters to more than three meters across. The molten plastic is pulled upwards from the die by a pair of nip rolls 4 to 20 meters above the die depending on the amount of cooling required. Changing the speed of these nip rollers will change the caliper of the film. Around the die sits a Cooling Ring. The air flow cools the film as it travels upwards. In the center of the die is an air outlet from which compressed air can be forced into the center of the extruded circular profile, creating a bubble. This expands the extruded circular cross section by some ratio (a multiple of the die diameter), this ratio is called the “blow-up ratio”.
Caliper In the release liner industry the caliper is defined as the thickness of a sheet or material measured under specific conditions, expressed in term appropriate to the material and technology involved. We typically use the term micro meter to specify the thickness of a carrier material.
Catalyst A material used in very small amounts to initiate a chemical change, for release coatings this means typically polymerization or crosslinking. With condensation cure silicone release coatings, the catalysts are organo-tin compounds, with addition cure silicone release coatings, the catalysts are rhodium or platinum complexes. The platinum catalysts are particularly subject to inhibition (or poisoning) by some antioxidants or other processing aids found in polyolefin stocks or polyolefin-coated paper, some size agents used in the manufacture of paper, and some clays used to make clay coated paper.
Cationic cure / UV cationic Reactions based on positive charged ions such as H+
Chill Roll A chill roller is typically a metal roll or drum which is internally chilled with water, to reduce the temperature of a web in a coating or printing line, after it has been heated for drying or curing. Chill rolls are also used to improve the effectiveness of re-moisturizing units.
Clay Coated Board A high-quality paperboard having a surface coating of pigment-like solids and appropriate binders. Clay coated board is the type of board on which clay is applied to fill the interstices between the fibers to provide an exceptionally smooth surface for high-quality printing and coating. The ink or coating liquid "sits" on the top of the surface, enabling a high gloss representation of the printing or coating.
Cling Tendency of adjacent materials to adhere to each other, as in blocking, except that the surface can be separated without any visible damage. Often caused by static electricity or result of chemicals which have been added in to material e.g. cling film.
Coat Weight The weight of a release coating or an extrusion coating per unit area of the substrate. This is expressed as pounds per ream or grams per square meter. The conversion factor is 1 pound per ream = 1.62 gsm
Coated Papers Coated paper is paper which has been coated by a compound to impart certain qualities to the paper, including weight, surface gloss, smoothness or reduced coating absorbency. Kaolinite or calcium carbonate are used to coat paper for high quality printing used in packaging industry, magazines and also in the release liner industry to improve the hold out of a silicone coating. The chalk or china clay is bound to the paper with synthetic viscosifiers, such as styrene-butadiene latexes and natural organic binders such as starch. The coating formulation may also contain chemical additives as dispersants, resins and PE, to give water resistance and wet strength to the paper, or to protect against ultraviolet radiation.
Coating in General A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. In many cases coatings are applied to improve surface properties of the substrate, such as appearance, adhesion, wettability, release against adhesives, corrosion resistance, wear resistance, and scratch resistance. In other cases, in particular in printing processes the coating changes the appearance of the product. Coating and printing processes involve the application of a thin film of functional material to a substrate, such as paper, fabric, film, foil or sheet stock. Loparex typically uses 'roll-to-roll' or 'web-based' coatings. A roll of substrate, when wound through the coating machine, is typically called a web. Coatings may be applied as liquids, gases or solids.
CoF / Coefficient of Friction There are different types of Frictions which might play a role in the release liner industry, the most common once are the static CoF, the sliding CoF and the rolling Friction. Especially when a moving web is processed thru a production line, the friction between the silicone surface and the rollers or solid standing bars can determine which silicone release system has to be chosen.
Color Concentrate Color concentrates are used in the manufacturing process of polymeric films or extrusion coatings. Color concentrates change the color of the plastic resin which is used to apply an extrusion coating or make a film. In co-extrusion lines, two different color concentrates to make two tone films. Loparex is using color concentrates in its filmic liner manufacturing and is also capable of making two tone films.
Co-Monomers Polyolefin’s made with one basic type of monomer are called homopolymers. Commonly used co-monomers in HDPE and L-LDPE extrusion are butene and hexene are called ALPHA OLEFINS. Other co-monomers used with ethylene to make extrusion coating grades are n-butyl acrylate (nBA), forming the co-polymer ethylene n-butyl acrylate (EnBA) and vinyl acetate (VA) , producing ethylene vinyl acetate (EVA). Depending on the type of co-monomere used in a base resin, the properties of the base resin will change.
Construction / Laminate A multi-layer laminate of web stocks. Usually consisting of a face stock, an adhesive layer, and a siliconized (or other release coated) backing.
Controlled Release Additive / CRA / RCA Controlled release additives are materials added to easy release polymer formulations which provide higher and controlled levels of release. Other terms are release controlled additives or release modifier.
Corona Treatment A surface treatment process which increases the surface energy of substrates to facilitate good wet out (and adhesion) of applied silicones (usually liquids). This is accomplished by passing the material to be treated through a corona generated by a high-voltage alternating current discharged to a ground. In air, this normally results in an oxidized surface caused by the ozone which is generated by the corona. Excessive corona treatment may result in the formation of volatile molecules some of which are speculated to act as inhibitors for platinum in addition cure silicones. A normal treatment level is 44 Dyne.
Creep / Cold Creep In the release liner industry the term cold creep is typically used in conjunction with plastic films. Cold creep in plastics is a phenomena which reorients the molecules in the plastic film, which can use e.g. an absolutely flat film to get a floppy edge over time.
Cross Direction / CD The direction at right angles (90 degree) to the machine direction in the plane of a sheet of paper (or web). The release liner industry also uses the term CD for cross direction and MD for machine direction.
Crosslink / Cross-linking The development of a three dimensional structure in a polymeric material by chemical reaction. With adhesives, this normally results in an increase in shear resistance, high temperature-resistance and solvent resistance. With release coatings, this will change the liquid coating into a solid coating which is not displaced or adhered too strongly by an applied adhesive.
Cure Curing of a material is a process of changing the properties of material by chemical reaction. The change may results from cross-linking or polymerization initiated via chemicals, catalysts, thermal treatment, radiation (UV or EB), or a combination of these elements.
Cure Temperature The temperature to which a material is subjected during curing, so the coating which needs to be cured can crosslink. Cure temperature also requires a cure time, which is the time needed to crosslink the coating to its desired end point of reaction.
Cure Time The time that a thermal cure coating has to be held at a certain (cure) temperature to first initiate (start) and then complete the curing / crosslinking process.
Curtain Coating Curtain coating is a process that creates an uninterrupted curtain of fluid that falls onto a moving web of paper, foil or film, without touching the web. The web moves at a regulated speed through the curtain to ensure an even coating. The curtain is created by using a slit at the base of a holding tank or by using a high precision die, allowing the liquid to fall upon the substrate. Most manufactures will also include a catch pan to retrieve and reuse the excess fluid, which is falling down on the sides of the web. The thickness of the coating layer that falls upon the object is mainly determined by the speed of the conveyor and the amount of material leaving the tank (Pump Speed). Curtain coating is a pre-metered method, which means that the amount of liquid required is supplying from the tank to the screen in order to be deposited on the substrate. Curtain coating is one of the technologies used in the converting industry to modify the properties of a substrates.
Degree of Cure The degree of cure is a term used to describe how much curable material has cured. In release coatings, we target a degree of cure which is higher than 95%.
Delamination / Composite Material Delamination is a mode of failure for composite materials. Modes of failure are also known as 'failure mechanisms'. In laminated materials, repeated cyclic stresses, impact, and so on can cause layers to separate, forming a mica-like structure of separate layers, with significant loss of mechanical toughness. Since composite materials are manufactured on release liner carrier it is important that the silicone does not transfer to the resin used in the composite material. Loparex is a leading manufacturer in composite carrying materials and has high end solutions which minimize or avoid silicone transfer.
Delamination / Laminate The delamination of a laminate is the separation of a release liner from the final product. Depending on the delamination speed release forces might vary. Loparex has special silicone systems which can offer stable release across different delamination speeds.
Delamination Speed The delamination speed is the stripping speed of the release liner, when it is removed from the sticky material. There is slow speed delamination like hand peels or high speed delamination like fully automated bottle labeling. Depending on the adhesive and the delamination speed of a specific application the silicone system has to be chosen carefully.
Die Any of various tools or devices used for imparting or cutting a desired shape or form from a material, usually to produce a label or a specifically sized sample.
Die Cut The line of severance between a pressure-sensitive label and its matrix or adjoining label made by the cutting edge of a die.
Die Cutting Die cutting is the process of using a die to shear webs of low strength materials, such as rubber, fiber, foil, cloth, paper, corrugated fiberboard, paperboard, plastics, pressure sensitive adhesive tapes, foam and sheet metal. Commonly produced items using this process include gaskets, labels, corrugated boxes, and envelopes. Loparex has a vast knowledge about which properties of a release liner will support the die cutting process of e.g. labels.
Differential Release Differential release refers to achieving two levels of release with two release surfaces (two liner or two sides of the same substrate) with an adhesive so that during the unwinding the adhesive remains on one release surface (the one with the higher release value) only, so that it may be applied to a substrate and the liner can then be removed completely e.g. like double side sticky carpet tape.
Dimensional Stability Dimensional stability indicates the resistance of a web to dimensional changes resulting from ambient atmospheric or other conditions. For example changes humidity the dimension and lay flat of a paper substrate.
Doctor Blade / Enclosed Doctor Blade An adjustable knife-like bar which controls the amount of material on a glue wheel or gravure cylinder. This is a very basic method of metering a coating. The more advanced type of this coating technology is the enclosed doctor blade, which has two blades and an enclosed and sometimes pressurized chamber, which pushes the coating into the gravure cells, allowing for a better controlled coat weight.
Dwell Time Dwell time is the time that a material is allowed to remain at one set of conditions before being subjected to another set of conditions (e.g., the time that a pressure sensitive adhesive is allowed to remain on a substrate prior to testing for peel adhesion, or the time in an oven to cure).
Dye Test / Dye Check A method of ascertaining the degree of coverage of the silicone on paper backings (coating quality). This is accomplished by applying a solution of dye, water, a surfactant, and optionally isopropanol, on the siliconised liner surface. The dye will color those places where the test solution contacts paper fibers which are sticking thru the silicone coating and would cause an undesired increase in release forces.
Dyne The dyne per centimeter is the unit traditionally used to measure surface tension. For example, the surface tension of distilled water is 72 dyn/cm at 25 °C (77 °F); in SI units this is 72 x 10−3 N/m or 72 mN/m. The surface treatment level of filmic surfaces to be siliconized should be between 42 and 48 dyn/cm
E-Beam / Electron Beam Electron beam in the release liner industry is a curing method for specialty silicone release systems. Electron beam processing or electron irradiation is a process of using high energy electrons, to crosslink a silicone liquid coating into a silicone rubber with release properties. This may take place under elevated temperatures and nitrogen atmosphere. Electron energies typically varies from the keV to MeV range, depending on the depth of penetration required. The irradiation dose is usually measured in Gray but also in Mrads. Where 1 Gy is equivalent to 100 rad. In polymers, an electron beam may be used on the material to induce effects such as chain scission (which makes the polymer chain shorter) and cross linking. Loparex uses E-beam technology and can offer specialty E-beam coatings for your application.
Elmendorf Test A standard test for determining the tear strength of paper or film.
Embossed / Embossing A term describing a surface that has printing or design in raised relief. The raised surface can be accomplished during the extrusion coating process while the extrusion coating is still soft and is pressed against an engraved cooling cylinder, which then transfers the raised image into the extrusion coating. Another method is to use an embossing station which reheats a film and embosses a new raised structure into the surface.
Emulsions An emulsion is a mixture of two or more liquids that are normally immiscible (nonmixable or unblendable). Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion should be used when both the dispersed and the continuous phase are liquids. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). In the release liner industry, emulsions are made from latex or silicone and are used for priming of substrates and for release coatings. Loparex uses a wide variety of addition and condensation cure emulsion types.
EVA / Ethylene vinyl acetate Ethylene vinyl acetate (also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene. Hot melt adhesives, hot glue sticks, top of the line soccer cleats, are usually made from EVA, usually with additives like wax and resin. EVA is also used as a clinginess-enhancing additive in plastic films or as tie layer in multi-layer film constructions.
Extractable - Atomic Absorption [AA -] Method The degree of cure can be measured by extracting uncured material from the silicone coating after it has been cured. For this a piece of release liner is submerged in a defined amount of solvent and the liner stays submerged for at least 24 hours. After this a sample of the solvent is analyzed by atomic absorption and the amount of extracted silicone is measured. If one calculates the amount of extracted silicone against the coat weight of the liner, one gets the amount of uncured silicone and silicone lights in the coating. Typically the amount of extractables should be below 5%, otherwise the adhesive can be negatively affected. For the electronics industry this level should be much lower and for this Loparex is offering its LOEX products.
Extractable - Coat Weight Differential Method Silicone extractable can be measured by measuring the silicone coat weight differential of a release liner before and after the liner has been exposed to a solvent for some time. This method can be used directly at a coating machine, but is not as accurate as the AA method.
Extrusion Coating Extrusion coating is the coating of a molten web of synthetic resin on to a substrate. It is a versatile coating technique used for the economic application of various plastics, notably polyethylene and poly propylene, onto paperboard, corrugated fiberboard, paper, aluminum foils, cellulose or plastic films. Loparex offers a wide range of these products, which we all silicone coat.
Extrusion die Loparex uses two types of extrusion dies. One is the a straight Mono or co-polymer extrusion die for extrusion coating of polyolefins on paper or film and the second is a round extrusion die for blown film co-polymer extrusion.
Face Stock A Face stock is a paper, film, fabric, foil, etc. which has been directly or indirectly coated with an adhesive. In the release liner industry a label material is a typical face stock, which usually gets printed and die cut as well.
Felt Side The side of the paper web which has been in contact with the drying felt during the paper making process. Since the water of the pulp is rinsed off thru the felt, the felt side of the paper is typically a bit more porous.
Fiber Tear The dislocation and rupture of paper or cloth fibers during the separation of the adhesive adherent interface.
Film Forming The property or ability of a liquid material (i.e., a solvent-based adhesive or an emulsion) to be cast in a dimensionally-stable continuous film like in a slot die or free falling curtain coating process. Film forming can also happen when an emulsion coating dries to quickly on its surface and blocking the water which wants to evaporate during the curing process. This type of film forming causes blistering which will lead to erradic release behavior.
Finish The surface appearance and properties of a paper sheet determined by its surface contour and gloss (antique, eggshell, vellum, machine, English, super calendered, etc).
Fish Eyes Relatively small deformations (pock marks) in an applied film caused by the entrapment of air between layers in the roll. They are not an indication of a quality defect in release coatings.
Flag A marker, usually strips of colored paper or board, inserted in rolls of coated web stock and extending from the edge to designate a deviation from a standard, such as a splice, defect or specification change or to mark a specific length of material.
Flame treatment Flame treatment, like corona treatment is used to change the surface properties of a substrate. The benefits of flame treatment over corona treatment are. • Higher treatment levels • Low treatment decay rates • Guaranteed no backside treatment • No ozone • No pin holing • No material gauge restrictions • Surface decontamination of film
Flexo Printing Flexography (often abbreviated to flexo) is a form of printing process which utilizes a flexible relief plate. It is essentially a modern version of letterpress which can be used for printing on almost any type of substrate, including plastic, metallic films, cellophane, coated paper and straight paper. It is widely used for printing on the non-porous substrates required for various types of food packaging (it is also well suited for printing large areas of solid color). In the release liner industry the flexo process is used for printing, priming and pattern coating. Loparex has a large number of flexo coating stations which can be used for various coating materials.
Flexographic Ink There are three main types of ink: water based, solvent based and 100 solids (UV curable) inks. The printing surface (substrate or web type) normally dictates what ink can be used. In the release liner industry flexo printing inks are printed directly onto the raw paper or film and may negatively interact with the silicone release coating. Therefore the flexography printing inks have to be chosen carefully.
Floppy Edge A floppy edge is a phenomena typically seen with plastic films, where the center of the film is a tiny bit shorter than the edges of the web, this causes low tension areas on the side of the web and the web in that area can flatter during the converting process, which is explained a floppy edge when viewed from the side lines of a machine. Floppy edge can appear and disappear in a roll during converting or can be there all the time, which can be seen in the roll as a star on the side of the roll.
Flow Out The ability of an adhesive, a coating, a primer or a sealer to level (flow out) on the surface of the substrate after they have been coated. The flow out can be affected by pretreatment of the surface with a flame or corona treater.
Fountain Roller Typically a Fountain Roller is used in flexography printing and it transfers the ink that is located in the ink pan to the second roller, which is the Anilox Roller.
Free Radical / Radicals Radicals (often referred to as free radicals) are atoms, molecules, or ions with unpaired electrons or an open shell configuration. Free radicals may have positive, negative, or zero charge. With some exceptions, these unpaired electrons cause radicals to be highly chemically reactive. Free radicals play an important role in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. In the release liner industry free radical polymerization is typically used in Acrylate based UV or E-beam silicone coatings.
Ghosting Ghosting is a phenomena where a ghost image of a backside print of a release liner re-appears as a ghost image in and end product like a graphic art liner. There can be numerous causes for ghosting.
Glassine paper Glassine is a very thin and smooth paper that has some resistance to air and water. It is translucent unless dyes are added to color it or make it opaque. It is manufactured by super calendering: after pressing and drying, the paper web is passed under very high pressure through a stack of alternating steel and fiber-covered rolls called a super calender at the end of the paper machine such that the paper fibers flatten facing in the same direction. Glassine papers typically have a PVA top coat to improve their anchorage properties.
Global Release Liner Industry The release liner industry is split up in two major sections. The In-house and In-Line manufacturer like Avery and Raflatac who make release liner but also coat the adhesive on it and apply the final face stock and commercial silicone coating companies like Loparex who custom manufacture release liner and sell them to those companies which apply a coating or some other sticky material to it. The global release liner market size in 2011 was in between 30 to 40 billion square meter and those were produced in approximately 350 - 450 production plants.
Gravure coating Gravure coating is a standard coating technology at Loparex. There are different setups for gravure coating. The main coating technologies which Loparex is using are: Direct Gravure, Indirect Gravure and Offset Gravure coating.
Gravure printing Rotogravure (Roto or Gravure for short) is a type of intaglio printing process; that is, it involves engraving the image onto an image carrier. In gravure printing, the image is engraved onto a cylinder because, like offset printing and flexography, it uses a rotary printing press. Once a staple of newspaper photo features, the rotogravure process is still used for commercial printing of magazines, postcards, and corrugated (cardboard) product packaging.
HDPE / High Density Polyethylene High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a polyethylene thermoplastic made from petroleum. It takes 1.75 kilograms of petroleum (in terms of energy and raw materials) to make one kilogram of HDPE. Loparex uses HDPE in its extrusion coating and filmic liner manufacturing processes. The mass density of high-density polyethylene can range from 0.93 to 0.97 g/cm3. Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular 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, 110 °C /230 °F continuously). High-density polyethylene, unlike polypropylene, cannot withstand normally required autoclaving conditions.
Heat Resistance Heat resistance is the ability to withstand the exposure to higher temperature without losing important properties. E.g. Loparex's Film Plus material is PET core which has been coated with two PE layers, which gives the product some PE like properties, but similar heat resistance like PET film.
Hexachloroplatinic Acid / Pt catalyst Chloroplatinic acid or hexachloroplatinic acid is the chemical compound usually found as the hexahydrate with the formula H2PtCl6·(H2O)6. This is one of the most readily available soluble compounds of platinum. It is rarely obtained in the pure state. The commercial product is the oxonium salt of the hexachloroplatinate(IV) anion. Therefore, the correct formula is [H3O]2[PtCl6]·4H2O. The related palladium compound, [H3O]2[PdCl6] is extremely unstable and has not been isolated in pure form. This is the main molecule used to make silicone based platinum catalyst.
High Release Additives High release additive is a general and older term for controlled release additive or a release modifier.
Hockey Stick Curve In the release liner industry the release behavior of release modifier agents is typically called a hockey stick, since the release curve will increase only slowly, if one adds between 1% and 50% of a release modifier, but will increase ever faster after one passes the addition level of 50%. In order to double the release force of a laminate one might need to add 50% release modifier, to triple the release force one might only need 60%.
Hold out The hold out is a property of a paper substrate. It determines how good a coating will stay on the surface of the substrate. A paper with a good hold out will consume lesser coating formulation compared with a paper which has a bad hold out and is porous.
Hot Melt Coating Application of a coating material which is solid at room temperature and by the use of applied heat will melt to a sufficiently low viscosity for coating. Hot melt adhesives are used widely in the release liner industry.
Hygroexpansivity Expansivity of a paper liner due to moisture or humidity exposure. A liner with unbalanced or excessive Hygroexpansion can be difficult to be converted, this is why Loparex is using extrusion coated materials to enclose the fiber based paper web, which will protect the fiber from exposure to water or moisture.
Inert Atmosphere Non-reactive atmosphere surrounding reactants. Usually this comprises introduction of nitrogen into the reaction chamber to force out air and to eliminate the negative effect of oxygen on the curing speed or the degree of cure of free radical polymer chemistries.
Inhibition In the release liner industry inhibition is typically something that we don't want (besides Inhibitors designed to extend pot life). Typically inhibition is something that slows down the cure of the release liner coating, so in general the cure of the silicones, but it can also affect the release values and the anchorage to the substrate. Inhibition can occur in addition and condensation cure thermal systems as well as in radiation cure systems. Chemicals which can inhibit the cure of a silicone system are additives used in the manufacturing of the substrate, chemicals which are used to make rubber rollers or can come from the environment. Inhibition can be slight and can be overcome by changes to the coating process or the coating formulation or can be as severe, that a coating of the substrate is no longer possible.
Inhibitor / Silicone Inhibitor Inhibitors are in the release liner industry are typically Alkinol or Maleate type of molecules, which are added into the silicone formulation to provide a long and stable pot life of the bath or a good thin film pot life on the coating rollers, to avoid gels etc..
Interface The area of contact between two adjacent surfaces. E.g. the silicone and the adhesive. In the release liner industry chemical reactions happening between two materials like the release agent and an adhesive are most critical. Understanding and manipulating these interfaces is what Loparex knows very well.
Label The Functional portion of o pressure-sensitive adhesive construction comprising the face stock and the adhesive which is die-cut into various shapes. The label market represents the largest market segment in the release liner industry.
Laminate A web material formed by bonding two or more web materials together. Laminate are e.g. PSA Labels, composite materials, multi-layer constructions of individual plastic and or paper webs.
Lay Flat The lay flat describes the property of a substrate to keep laying down flat on a flat surface, without pulling up its edges, when being exposed to humidity changes or how good it lays flat after a paper has been re-moisturized. Typically paper has poor lay flat properties, which are greatly improved when the paper gets one or two side extrusion coated.
LDPE / Low Density Polyethylene Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. Despite competition from more modern polymers, LDPE continues to be an important plastic grade. In 2009 the worldwide LDPE market reached a volume of US$22.2 billion (15.9 billion Euro). Loparex uses LDPE resins in extrusion coating as well as filmic liner manufacturing. LDPE is defined by a density range of 0.910–0.940 g/cm3. It is not reactive at room temperatures, except by strong oxidizing agents, and some solvents cause swelling. It can withstand temperatures of 80 °C continuously and 95 °C for a short time. LDPE has more branching (on about 2% of the carbon atoms) than HDPE, so its intermolecular forces (instantaneous-dipole induced-dipole attraction) are weaker and its tensile strength is lower.
Legging / Filimentation The stringing-out (filimentation) of a pressure-sensitive adhesive when a label or tape is drawn away from a substrate, its release liner, or its matrix.
Leveling / Flow Out The ability of a coating to flow sufficiently so that its surface will be relatively flat and free from irregularities resulting from its application.
Lifting Pulling away from the substrate a section of an applied label or tape. Automatic lifting is the dispensing process when labels are applied to bottles. When the laminate is pulled around a sharp corner the face stock is lifting off the release liner and adheres to e.g. a bottle which then pulls the rest of the face stock away from the release liner.
Loop Tack A test to determine the strength of immediate adhesion at a pressure-sensitive adhesive tape to a substrate (usually stainless steel). The value from this test has been shown to be very sensitive to the contamination at the adhesive surface via transferred silicone, adhesive oxidation, antioxidant, blooming, etc.
Machine Direction / MD Machine Direction is the direction of web materials parallel to its forward movement on a machine (coater). Typically our industry uses the abbreviation MD. The other term use is CD which stands for cross direction.
Machine Finish / MF / MF Grade The paper finish obtained on the paper machine. Commonly referred to as MF grade.
Machine finished Kraft paper / MFK Machine Finished Kraft paper, is the paper as it comes from a standard paper machine.
Machine Glazed / MG Machine glazing is a surface treatment on the wire side of a paper sheet which has been passed over a single, large, diameter, glossy, steam-heated, chrome-plated cylinder, typically called Yankee Cylinder. The heat glazes the surface of the paper and gives it gloss and a better hold out.
Malachite Green Malachite Green is also a test solution for the coating quality of a silicone coating. Malachite green is an organic compound that is traditionally used as a dye for materials such as silk, leather, and paper. Although called malachite green, the compound is not related to the mineral malachite — the name just comes from the similarity of color.
Matrix The face and adhesive layers of a pressure sensitive construction surrounding the die cut labels. This is usually removed after die cutting to obtain pressure sensitive labels mounted on a release liner.
Matrix Stripping The act of removing the matrix surrounding the label. This is often done at high speed. The cross member (cross direction) between labels is subjected to very high stresses due to high peel rates at low peel angles.
Matte Finish A dull finish. Loparex produces a lot of C2S (double side coated) extrusion coated liner. Typically one side is made as a matt finish and one side is made with a glossy finish.
Mayer rod coating / rod coating The Mayer rod is a stainless steel rod that is wound tightly with a stainless steel wire. The rod is used to meter off the excess coating solution and control the coat weight. The wet thickness after metering is controlled by the diameter of the wire used to wind the rod. Several rods can be placed in series to achieve a more homogenous coating.
MDPE / Medium Density Polyethylene Medium-density polyethylene (MDPE) is a type of polyethylene defined by a density range of 0.926–0.940 g/cm3. It is less dense than HDPE, which is more common. MDPE can be produced by chromium/silica catalysts, Ziegler-Natta catalysts or metallocene catalysts. MDPE is defined by a density range of 0.926–0.940 g/cm3. MDPE has good shock and drop resistance properties. It also is less notch sensitive than HDPE. 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. Loparex uses MDPE for specialty applications.
Melt Index (MI) / Melt Viscosity All poly olefin resins are a mixture of short and long carbon based molecule chains. The flow characteristic of this molecule blend is expressed by the melt index (MI) which is tested at 374F under specific pressure. As the average molecular weight increases the MI DECREASES. The resin’s flow, when melted, increases with increasing MI, which means it contains more short chain molecules. Blown film resins have a low melt index to give the bubble stability and resins for extrusion coating have higher melt indexes.
Migration / Tape Migration / Migration Test The migration test is a tape test which can be done directly during production of a release liner or at a later point in time. A specific tape is applied 3-4 times to the surface or the siliconized material and then the adhesive side of the tape is placed against another section of the adhesive tape, whereas both of these sections had to be in contact with the silicone surface. Then the release force of the adhesive against itself is tested. If silicone has transferred to the adhesive, the release force will now be lower. With enough experience one can make predictions about the silicone extractable level (degree of cure) of the silicone.
Migration of Plasticizer Loss of plasticizer from a polymeric composition (e.g., a vinyl) with subsequent absorption by an adjacent phase of lower plasticizer concentration (e.g., an adhesive). This may result in making the vinyl more brittle (raising the Tg) and lowering the adhesive's shear properties.
Miscible Capable at being mixed to produce one phase; mutually soluble in each other.
Molecular weight distribution When polymers are made up of molecular chains which are close to the average molecular chain length, the polymer is said to have a “Narrow molecular weight distribution” In general, poly olefin resins with a narrow molecular weight distribution have greater stress cracking resistance and better optical properties. Resins with broad molecular weight distributions generally have greater impact strength and better processability. Also silicone polymers can have different molecular weights within one product.
Neocarmin Neocarmin is a test solution which is used to determine coverage of a silicone coating on paper.
Non-Blocking Pertaining to an applied material that will not adhere to itself and/or other surfaces under normal storage conditions in roll form or as stacked sheets.
Offset A printing defect characterized by partial transference of ink from a freshly printed surface to an adjacent contacting surface when the materials are stacked or rolled.
Ooze / Edge ooze A "squeezing out" of the adhesive out of the laminate. When this occurs, the edges of a roll of tape become tacky.
Orange Peel Orange peel is a surface irregularity resembling the skin of an orange in texture when a filmic surface is coated with a release coating like silicone. There are several ways to approach this issues and to avoid orange peel in release liner applications.
PET / BoPET / Biaxially-oriented polyethylene terephthalate PET film also called polyester film is made from biaxially stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties. It is the film that is used most commonly in the release liner industry and offers the highest heat resistance. Loparex offers a wide variety of silicone coated PET films to the industry.
Photo Initiator / Photoinitiator In radiation-initiated curing or polymerization systems (e.g. UV), the chemical which when exposed to the radiation breaks certain chemical bonds and forms an active species which initiates polymerization or cross-linking reactions. In some silicone systems which are UV curable, the catalyst is a photoactive complex. Under UV radiation the complex is broken and cure is initiated via the active catalytic species generated. The same silicone systems which need a photo initiator for curing under UV, don't need it when cured with E-beam.
Pin Holes Pin hole is a term for uncoated spots on the surface of a release liner. Pin holes can be caused e.g. by loose debris on the surface of the web, holes in the raw substrate, gels on the coating roller, other pre-treatment processes or numerous other reasons. Pin holes typically cause release value instabilities or blocking of the release liner and the adhesive.
Platinum / Pt / catalyst The name of Platinum is derived from the Spanish term platina, which is literally translated into "little silver". It is a dense, malleable, ductile, precious, gray-white transition metal. It is one of the rarest elements in the Earth's crust and has an average abundance of approximately 5 μg/kg. It occurs in some nickel and copper ores along with some native deposits, mostly in South Africa, which accounts for 80% of the world production. Because only a few hundred tons are produced annually, it is a scarce material, and is highly valuable and is a major precious metal commodity. In the release liner industry Platinum is still the main catalyst used to initiate the chemical reaction of silicones. Probably 70% of all release liner coatings use Platinum as catalyst. Until 1999 the Platinum price was quite stable at around $400 per ounce, since then Platinum pricing has increased until 2012 to ~$1500 per ounce and is believed to rise further.
Polyolefin / Poly olefin A polyolefin is a polymer produced from a simple olefin (also called an alkene or with the general formula CnH2n) as a monomer. For example, polyethylene is the polyolefin produced by polymerizing the olefin named ethylene. An equivalent term is polyalkene; this is a more modern term, although polyolefin is still used in the petrochemical industry. Polypropylene is another common polyolefin which is made from the olefin called propylene. Other thermoplastic polyolefins are: polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutene-1 (PB-1); Polyolefin elastomers (POE): polyisobutylene (PIB), Ethylene propylene rubber (EPR), ethylene propylene diene Monomer (M-class) rubber (EPDM rubber). The most common thermoplastic olefine in the release liner industry are PE, PP and PET.
Polystyrene (PS) Polystyrene is an aromatic polymer made from the monomer styrene, which is a liquid petrochemical. Polystyrene is one of the most widely used plastics, especially in packaging applications. As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled. This temperature behavior is exploited for molding and extrusion, since it can be cast into molds with fine detail. Polystyrene can be transparent, white, or, upon dying, various colors.
Post Cure A continuation of the cross-linking reaction leading to increased degrees of cure following exposure to cure initiation energy (thermal, UV). Some silicone systems (tin catalyzed, condensation) may post cure for as long as three weeks, and others (platinum catalyzed, vinyl addition) may post cure in a few days or just hours. The amount of post cure is dependent on the degree of initial cure and the chemical and physical environment surrounding the reactants.
Pot Life / pot-life The time period in which a material remains effective and/or coatable. In the release liner industry, pot life is typically defined as an increase in batch viscosity. Pot life = starting batch viscosity multiplied by two.
PP / Polypropylene Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging and labeling, textiles (e.g., ropes, thermal underwear and carpets), stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes. An addition polymer made from the monomer propylene, it is rugged and unusually resistant to many chemical solvents, bases and acids. Loparex uses Polypropylen in its extrusion coating and filmic liner manufacturing processes. Most commercial polypropylene is isotactic and has an intermediate level of crystallinity between that of low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Polypropylene is normally tough and flexible, especially when copolymerized with ethylene.
Primer A primer can be a water based, solvent based or 100% "solids" liquid material, which is applied a raw paper or raw film to enhance the bond between the substrate / web and the final coating. The final coating can be a silicone release material or a poly olefin extrusion coating.
Quick Stick / Tack Quick stick or also called Tack, finger tack, initial adhesion, grab, etc. is the property of a pressure sensitive adhesive that allows it to adhere to a surface under very light contact pressure. It is determined by the ability of the adhesive to wet the surface contacted quickly.
Radiation cure silicone coatings / UV coatings Radiation cure silicones are split up in two different cure mechanisms, free radical and cationic. Both cure mechanism have found their place in the release liner industry and are used in various specialty applications. Loparex is using UV coatings in different manufacturing sites to offer its customers special release solutions.
Radiation Curing / Electron beam Curing Electron beam (E-beam) processing or electron irradiation is a process which involves using electrons, usually of high energy, to treat an object for a variety of purposes. This may take place under elevated temperatures and nitrogen atmosphere. Possible uses for electron irradiation include sterilization and to cross-link polymers. Electron energies typically varies from the keV to MeV range, depending on the depth of penetration required. The irradiation dose is usually measured in Gray but also in Mrads. Where 1 Gy is equivalent to 100 rad. Loparex uses E-beam technology for specialized customer applications, which cannot be served with standard addition, condensation or radiation cure systems.
Ream / Ream Size A number of sheets of paper, usually 500, according to paper type or grade. For purposes of certain types of testing a ream is considered 500 sheets. A commonly used figure is 3,000 square feet or 432,000 square inches.
Release (1) The act of freeing or separating a pressure-sensitive adhesive from its release liner. The following adjectives are often used to describe the perception of release: a.) Low Forces = easy, low, free b.) High Forces : high, tight, hard c.) Force oscillation = noisy, raspy, zippy (as opposed to ”smooth”)
Release (2) The force required to separate a pressure sensitive label or tape from its release liner under specified conditions of peel angle and speed.
Release Coating A release coating is typically a silicone based material. However other materials have also shown some form of release properties but their uses is limited. Silicones have the best and most stable release properties. Loparex can offer silicone based and non-silicone based release coatings for every application.
Release Liner Backing The component of the pressure-sensitive construction which functions as a protective carrier for the pressure-sensitive adhesive. It is separated from the adhesive and the face stock prior to their application to a substrate.
Release values Silicone systems and formulations are able to generate a wide range of release values and in general terms are called premium, easy, medium, tight and super tight. Depending on the adhesive theses system can generate release forces of 1 N/m up to several hundred N/m.
Release values / Units Typically the release values are expressed in N/m, cN/cm, g/inch.
Rheology The determination of a material’s ability to flow under a range of degrees of stress, stress rates, and temperatures.
Rub off / Rub off test Rub off is a term to describe the anchorage of a coating on the substrate. Typically it is tested by rubbing firmly with a finger over the silicone coating. Now one can feel if the resistance of the silicone against the finger is dropping or one uses an adhesive tape to see if the release force at the point where the surface was rubbed has changed. In bad instances, one can see a white powder on the surface. Typically the rub off test is expressed in a rating from 1 to 6, whereas 1 is perfect (the silicone is fully anchored on the surface) to 6 which is the worst (the anchorage has completely failed). The anchorage of the silicone to the surface of the paper can be negatively affected over time and a coating which showed perfect anchorage can show anchorage problems after some time, typically due to wrong storage conditions or internal and unwanted chemical reactions, caused by chemicals coming from other components in the end product.
Shelf Life Shelf life is the length of time in transit or in a warehouse that a material, will remain in an acceptable condition under supplier recommended storage and transportation conditions and in its unopened packaging. Material which is beyond its shelf life, might still be usable but the properties are no longer guaranteed by the supplier.
Shirlastain A Shirlastain A is a test solution to check the coating quality of a release coating on paper.
Silicone / Crosslinker In order for the silicone to be able to form a network which will lead to a silicone rubber like release material, silicone polymers and silicone resins will have to be crosslinked. The most common crosslinker is H-Siloxane and H-Siloxane based Co-polymers.
Silicone / reactive groups Silicone polymers or resins are supplied with different reactive groups. The most common once are Vinyl, Hexenyl, Hydroxy, Acrylate and Vinylether.
Silicone polymer Silicone polymers are the main base material for release coatings in our industry. Typically these silicones are polydimethyl siloxanes which have been functionalized with different reactive groups so they can be used in condensation, addition or radiation cure systems.
Silicone supplier There are only a few companies around the world who produce silicones for the release liner industry, with somewhat different product offerings. The main companies are (sorted alphabetically) Bluestar Silicones, Dow Corning, EVONIK, KCC Silicones, Momentive, Shin-Etsu and WACKER AG. As a leading supplier of release liner materials, Loparex stays up to date with the offerings of all silicone suppliers in order to provide its customers with customized solutions for each application.
Silicone system There are thermal and radiation cure silicone systems available in our industry for silicone coating, which are delivered as Solvent based, Solvent free and Water based systems. Within those general system categories the reaction mechanism can vary like addition cure, condensation cure, free radical or cationic. Each silicone system offers unique properties, which can solve the numerous challenges which release liner face in the market. Loparex manufactures over 2000 different silicone systems and liner combinations and is the most versatile and knowledgeable release liner manufacturer in the world.
Size A chemical substance, such as resins, starch or synthetic polymers, coated on a surface (e.g. paper) to reduce water absorption, scuffing, oil penetration, etc.
Slip Stick Slip Stick is a phenomena, known from production processes, where the release liner is removed in stop and go intervals. Every time the web starts moving again the release values might spike in the beginning, which can cause severe production issues. The interactions between the silicone release system in combination with the customers adhesive is something that needs to be understood to offer a trouble free product.
Smear Test A quick subjective test for determining whether the silicone has cured sufficiently. In order to do a smear test typically makes a firm finger stroke across the cured silicone surface and observing whether a greasy streak shows up or not. Depending on how severely the surface has been changed a rating from 1 to 6 can be given, whereas 1 is the best (silicone is fully cured) and 6 is the worst (silicone is not cured at all).
Smoothness Test The relative smoothness of a paper surface is determined by measuring the time for a specified volume of air to pass under a specific test piece resting on the paper surface. The shorter the time the rougher is the surface of the paper.
Solvent A solvent is a liquid, solid, or gas that dissolves a solute (a chemically different liquid, solid or gas), resulting in a solution. The maximum quantity of solute that can dissolve in a specific volume of solvent varies with temperature. Common solvents in the release liner industry are Toluene, Xylene, White Spirit, Heptane, Ethyacetate and the like.
Solvent Resistance Resistance of a material to a solvent. In the release liner industry these solvents are primarily liquids.
Solvents and silicones In the release liner industry a solvent is used to dissolve a long molecular chain silicone or a silicone resin, so its viscosity can be coated by a coating line or to reduce the coat weight amount. Loparex can handle solvents in some of the coating lines in North America, Europe and Asia.
Splicing Splicing in the release liner industry is a term to describe the joining of two single webs, to make bigger rolls. Since splices can cause issues for the downstream web converting Loparex tries to minimize the amount of splices for its customers.
Static Control Methods of eliminating or reducing static electricity in plastic materials such as film stocks. This is sometimes found to be necessary to obtain a uniform coating of silicone on a polymer film backing. This is often accomplished by dragging a grounded metallic tinsel on the web or by passing the web under a radioactive source which ionizes the surrounding air.
Subsequent Adhesion A tape adhesion value following contact with a release composition. This is normally done as a function of aging in contact with the release liner and is compared against the values achieved with no contact. The unit that this is expressed in is Percent. So if the adhesive tape has lost 10% of its initial tack after being in contact with a release liner, the subsequent adhesion value is 90%. A typical test tape to measure subsequent adhesion is TESA 4154 or TESA A7475.
Substrate The surface to which material (i.e., a pressure-sensitive adhesive) is applied.
Super Calendered Kraft paper / SCK SCK paper is similar to a Glassine paper, but typically has no surface coating.
Surface Energy A numerical expression in dynes/cm of the cohesive energy of the surface molecules. Liquids which have a lower surface energy than a solid will normally wet or spread on that solid. Liquids or liquid like materials (i.e., a pressure-sensitive adhesive) which have a higher surface energy than the solid (i.e. a silicone release coating) with which they are in contact, do not wet these solids well and thus do not form a strong adhesion to such substrates. Heterogeneous compositions will tend to reduce their surface energy by exuding the lowest surface energy component to the surface or through orientation of molecules so that the lowest surface energy portion of a molecule is on the surface and the higher surface energy portion of the molecule is pointed away from the surface (into the bulk).
Surface Sized Paper that has been treated with starch or other sizing material at the size press of the paper machine.
Surface Tension Surface Tension reflects the cohesive property of a liquid which causes it to reduce its total energy by assuming a spherical shape to obtain the smallest surface area. (see also Surface Energy)
Surface Treatment Methods for treatment of surfaces (such as low surface energy poly olefins) to increase their surface energy and thus increase their ability to be wet by inks, paints, lacquers and adhesives. Chemical, flame and corona are examples of surface treatments.
Surfactant A material used in small quantities which affects the tendency of liquids (water) to wet or penetrate. Those which decrease the surface tension are wetting, dispersing, foaming, penetrating, or detergent agents. Those which increase the surface tension act as defoaming or demulsifying agents.
Sustainability Sustainability is the capacity to endure. For humans, sustainability is the long-term maintenance of responsibility, which has environmental, economic, and social dimensions, and encompasses the concept of stewardship, the responsible management of resource use. In ecology, sustainability describes how biological systems remain diverse and productive over time, a necessary precondition for the well-being of humans and other organisms. Long-lived and healthy wetlands and forests are examples of sustainable biological systems. Healthy ecosystems and environments provide vital resources and processes (known as "ecosystem services"). There are two major ways of managing human impact on ecosystem services. One approach is environmental management; this approach is based largely on information gained from educated professionals in earth science, environmental science, and conservation biology. Source Wikipedia. http://www.loparex.com/en/media-detail.aspx?ID=2&Type=1
Tack The properly of a pressure-sensitive adhesive which causes it to adhere to a substrate with a minimum of pressure and time.
Telescoping A sideways sliding of a wound roll. Where one layer is sliding over the other, such that the roll looks like a funnel or telescope. Especially with very smooth filmic substrates like PET films or poly coater papers this can occur. Loparex has found ways to avoid telescoping of rolls when smooth surfaces have been coated.
TESA 4154 Test Tape Like tesa® 7475 and tesa® 7476, tesa® 4154 or also called T154 is a especially designed test tape for the characterization of silicone coated release liner. A typical test method represents FINAT 10 and FINAT 11. tesa® 4154 features a typical modified rubber based adhesive to record and standardize the interaction of a cured silicone coating and a rubber based adhesive. Additionally it is used as a test tape for the migration test. T154 test tape can also be used for the measurement of the grade of curing of a silicone by measuring the subsequent adhesion in accordance with the FINAT 11 test method. Loparex uses the tesa® 4154 test tape in some of its manufacturing plants to characterize the release coatings or for migration testing.
TESA A7475 Test Tape tesa® 7475 is a especially designed test tape for the characterization of silicone coated release liner. A typical test method represents FINAT 10 and FINAT 11. tesa® 7475 features a typical modified acrylic adhesive to record and standardize the interaction of a cured silicone coating and an acrylic adhesive. Additionally it shows a significant interaction with the Si-H Groups of a silicone crosslinker. A 7475 test tape can also be used for the measurement of the grade of curing of a silicone by measuring the subsequent adhesion in accordance with the FINAT 11 test method. Loparex uses the A 7475 test tape in all of its manufacturing plants to characterize the release coatings.
TESA K7476 Test Tape tesa® 7476 is a especially designed test tape for the characterization of silicone coated release liner. A typical test method represents FINAT 10. tesa® 7476 features a typical rubber based adhesive to record and standardize the interaction of a cured silicone coating and an rubber adhesive. Additionally it shows significant property in detecting uncoated spots in a release coating. Loparex uses the K7476 test tape in almost all of its manufacturing plants to characterize the release coatings.
Thermal Cure Systems Thermal cure release coatings are silicone or non-silicone release coatings which need thermal heat to initiate the curing process. Different technologies like air-foil or Infrared heat can be used to heat up the release coatings to their cure temperature. Thermal cure silicone systems are the most popular silicone release systems for release applications and probably make up 90% of the coatings in the release liner industry. Thermal cure systems can use the addition cure or condensation cure mechanism. Loparex can offer a wide variety of thermal cure silicone systems for your specialty applications.
Thermoplastic A Thermoplastic, also known as a thermo softening plastic, is a polymer that becomes pliable or moldable above a specific temperature, and returns to a solid state upon cooling. Most thermoplastics have a high molecular weight, whose chains associate through intermolecular forces; this property allows thermoplastics to be remolded because the intermolecular interactions spontaneously reform upon cooling. In this way, thermoplastics differ from thermosetting polymers, which form irreversible chemical bonds during the curing process; thermoset bonds break down upon melting and do not reform upon cooling. However thermoplastic materials can be crosslinked by E-beam radiation or chemicals, which make them more heat resistant but no longer recyclable.
Tie Coat One layer of a coating system used to improve the adhesion of adjacent coats.
Tie Layer One layer of an extrusion coated product which adheres to each layer next to it, but those two layers next to the tie layer would not stick to each other. The tie layer allows the bond between two polymeric materials which usually do not bond with each other.
Transfer Tape An unsupported pressure-sensitive adhesive applied to a two-side release coated liner like a carpet tape. There are many applications in the release liner industry which are using this type or similar types of construction.
Unwind / Unwind Adhesion / Un-Rolling Force The force required to remove tape from a roll.
UV cure / Ultra Violet Cure Ultraviolet curing also called UV curing is a photochemical process in which high-intensity ultraviolet light is used to cure silicone release coatings, inks or adhesives. Loparex can offer a wide variety of specialty UV cure release coatings for various applications.
Web The web in the release liner industry is the term for a moving substrate which will be coated with the release agent and is supplied in large rolls to the coating machine.
Web cleaning Web cleaning is an in-line process used to remove debris from the webs surface before coating it. Loose debris on the surface can lead to uncoated spots in a release liner surface and therefor to unpredictable release behavior.
Zippy Release Zippy release describes a release force phenomena, where the release force is fluctuating and is typically detected during high speed delamination. Loparex has found ways to eliminate zippy release for various applications.
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