Coating
Encyclopedia
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, wetability, corrosion resistance, wear resistance, and scratch resistance. In other cases, in particular in printing processes and semiconductor device fabrication (where the substrate is a wafer
), the coating forms an essential part of the finished 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. This article discusses what is frequently termed 'roll-to-roll'
or 'web-based' coating. A roll of substrate, when wound through the coating machine, is typically called a web.
Coatings may be applied as liquid
s, gas
es or solid
s. Coatings can be measured and tested for proper opacity and film thickness by using a drawdown card
.
The main coating and varnishes for the printing industry include:
Covering
-Mathematics:*In topology:** Covering map, a function from one space to another with uniform local neighborhoods** Cover , a system of sets whose union is a given topological space...
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, wetability, corrosion resistance, wear resistance, and scratch resistance. In other cases, in particular in printing processes and semiconductor device fabrication (where the substrate is a wafer
Wafer (electronics)
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
), the coating forms an essential part of the finished product.
Coating and printing processes involve the application of a thin film
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
of functional material to a substrate, such as paper, fabric
Fabric
A fabric is a textile material, short for "textile fabric".Fabric may also refer to:*Fabric , the spatial and geometric configuration of elements within a rock*Fabric , a nightclub in London, England...
, film, foil or sheet stock. This article discusses what is frequently termed 'roll-to-roll'
Roll-to-roll processing
In the field of electronic devices, Roll-to-roll processing, also known as web processing, reel-to-reel processing or R2R, is the process of creating electronic devices on a roll of flexible plastic or metal foil...
or 'web-based' coating. A roll of substrate, when wound through the coating machine, is typically called a web.
Coatings may be applied as liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
s, gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
es or solid
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
s. Coatings can be measured and tested for proper opacity and film thickness by using a drawdown card
Drawdown card
Drawdown cards are used for testing paints and coatings through wet film preparation.Black and white cards are used to measure both opacity and contrast ratio. By measuring reflectance values of both parts of the card one can gain a quantitative opacity value of a paint sample....
.
Functions
- PrintingPrintingPrinting is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....
(text or decoration) such as on paper, fabric, and flexible packaging - Self adhesive properties such as for tape, labels and packaging
- Melt-adhesive properties such as for vacuum seal and heat seal applications
- "Release" coatings such as the liner of a double-sided tape or vinyl stickers
- Low surface energy coatings to act as a non-stick surface
- Optical properties such as tint, color, anti-reflection, and holographics
- Photo-sensitivity such as for photographic film and paper
- Electronic properties such as passivity or conduction as with flexible circuits
- Magnetic properties such as for magnetic media like cassette tapes and floppy disks
- Water-resistant or water-proof coatings, such as for fabrics or paper, or on wood surfaces such as outdoor furniture, patio decks, yacht hulls and decks.
- Scent properties such as scratch and sniffScratch and sniffScratch and sniff technology generally refers to things that have been treated with a microfragrance coating. When scratched, the coating releases an odor that is normally related to an image being displayed under the coating...
stickers and labels
Chemical vapor deposition
- Metalorganic vapour phase epitaxyMetalorganic vapour phase epitaxyMetalorganic vapour phase epitaxy , also known as organometallic vapour phase epitaxy or metalorganic chemical vapour deposition , is a chemical vapour deposition method of epitaxial growth of materials, especially compound semiconductors, from the surface reaction of organic compounds or...
- Electrostatic spray assisted vapour deposition (ESAVD)
Physical vapor deposition
- Cathodic arc depositionCathodic Arc DepositionCathodic arc deposition or Arc-PVD is a physical vapor deposition technique in which an electric arc is used to vaporize material from a cathode target. The vaporized material then condenses on a substrate, forming a thin film...
- Electron beam physical vapor depositionElectron Beam Physical Vapor DepositionElectron Beam Physical Vapor Deposition or EBPVD is a form of physical vapor deposition in which a target anode is bombarded with an electron beam given off by a charged tungsten filament under high vacuum. The electron beam causes atoms from the target to transform into the gaseous phase...
(EBPVD) - Ion platingIon platingIon plating is a physical vapor deposition process that is sometimes called ion assisted deposition or ion vapor deposition and is a version of vacuum deposition. Ion plating utilizes concurrent or periodic bombardment of the substrate and depositing film by atomic-sized energetic particles...
- Ion beam assisted depositionIon beam assisted depositionIon beam assisted deposition or IBAD or ""IAD"" is a materials engineering technique which combines ion implantation with simultaneous sputtering or another physical vapor deposition technique...
(IBAD) - Magnetron sputtering
- Pulsed laser depositionPulsed laser depositionPulsed laser deposition is a thin film deposition technique where a high power pulsed laser beam is focused inside a vacuum chamber to strike a target of the material that is to be deposited...
- Sputter depositionSputter depositionSputter deposition is a physical vapor deposition method of depositing thin films by sputtering, that is ejecting, material from a "target," that is source, which then deposits onto a "substrate," such as a silicon wafer...
- Vacuum depositionVacuum depositionVacuum deposition is a family of processes used to deposit layers atom-by-atom or molecule-by-molecule at sub-atmospheric pressure on a solid surface. The layers may be as thin as one atom to millimeters thick . There may be multiple layers of different materials...
- Vacuum evaporationVacuum evaporationVacuum evaporation is the process of causing the pressure in a liquid-filled container to be reduced below the vapor pressure of the liquid, causing the liquid to evaporate at a lower temperature than normal...
, evaporation (deposition)Evaporation (deposition)Evaporation is a common method of thin film deposition. The source material is evaporated in a vacuum. The vacuum allows vapor particles to travel directly to the target object , where they condense back to a solid state...
Chemical and electrochemical techniques
- AnodisingAnodisingAnodizing, or anodising in British English, is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. The process is called "anodizing" because the part to be treated forms the anode electrode of an electrical circuit...
- Conversion coatingConversion coatingConversion coatings are coatings for metals where the part surface is converted into the coating with a chemical or electro-chemical process. Examples include chromate conversion coatings, phosphate conversion coatings, bluing, black oxide coatings on steel, and anodizing. They are used for...
- Anodizing
- Chromate conversion coatingChromate conversion coatingChromate conversion coating is a type of conversion coating used to passivate aluminum, zinc, cadmium, copper, silver, magnesium, and tin alloys. It is primarily used as a corrosion inhibitor, primer, decorative finish, or to retain electrical conductivity. The process is named after the chromate...
- Plasma electrolytic oxidationPlasma electrolytic oxidationPlasma electrolytic oxidation , also known as microarc oxidation , is an electrochemical surface treatment process for generating oxide coatings on metals. It is similar to anodizing, but it employs higher potentials, so that discharges occur and the resulting plasma modifies the structure of the...
- Phosphate (coating)
- Ion beam mixingIon Beam MixingIon Beam Mixing is a process for adhering two multilayers, especially a substrate and deposited surface layer. The process involves bombarding layered samples with doses of ion radiation in order to promote mixing at the interface, and generally serves as a means of preparing electrical junctions,...
- Pickled and oiledPickling (metal)Tarnision is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, rust or scale from ferrous metals, copper, and aluminum alloys. A solution called Tarnision liquor, which contains strong acids, is used to remove the surface impurities...
, a type of plate steelSteelSteel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
coating. - PlatingPlatingPlating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years, but it is also critical for modern technology...
- Electroless plating
- ElectroplatingElectroplatingElectroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal...
- Sol-gel
Spraying
- High velocity oxygen fuel (HVOF)
- Plasma spraying
- Thermal spraying
- Plasma transferred wire arc thermal spraying
Optical coatings
- Antireflection coating, to reduce reflection
- A mirrorMirrorA mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...
coating to enhance it
Other
- Dip-coatingDip-coatingthumb|A schematic of the continuous dip coating process.Dip coating is a popular way of creating thin films for research purposes. Uniform films can be applied onto flat or cylindrical substrates...
- EpitaxyEpitaxyEpitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate, where the overlayer is in registry with the substrate. In other words, there must be one or more preferred orientations of the overlayer with respect to the substrate for this to be termed epitaxial growth. The...
(Vapor-phase, Liquid-phase) - Vitreous enamelVitreous enamelVitreous enamel, also porcelain enamel in U.S. English, is a material made by fusing powdered glass to a substrate by firing, usually between 750 and 850 °C...
- PaintPaintPaint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
- Enamel paintEnamel paintEnamel paint is paint that air dries to a hard, usually glossy, finish, used for coating surfaces that are outdoors or otherwise subject to hard wear or variations in temperature; it should not be confused with decorated objects in "painted enamel", where vitreous enamel is applied with brushes and...
- Silicate mineral paintSilicate mineral paintSilicate mineral paints or silicate emulsion paints are mineral based coatings formulated with potassium silicate or sodium silicate, otherwise known as waterglass as the binder, combined with inorganic, alkaline-resistant pigments. Traditionally, they have been fully inorganic and are...
- Enamel paint
- PolymerPolymerA polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
coatings, such as Teflon - Powder coatingPowder coatingthumb|right|Aluminium extrusions being powder coatedPowder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler...
- Fusion bonded epoxy coatingFusion bonded epoxy coatingFusion bonded epoxy coating, also known as fusion-bond epoxy powder coating and commonly referred to as FBE coating, is an epoxy based powder coating that is widely used to protect steel pipe used in pipeline construction, concrete reinforcing bars and on a wide variety of piping connections,...
(FBE coating)
- Fusion bonded epoxy coating
- Molecular beam epitaxyMolecular beam epitaxyMolecular beam epitaxy is one of several methods of depositing single crystals. It was invented in the late 1960s at Bell Telephone Laboratories by J. R. Arthur and Alfred Y. Cho.-Method:...
- Sheradizing
- Spin coatingSpin coatingSpin coating is a procedure used to apply uniform thin films to flat substrates. In short, an excess amount of a solution is placed on the substrate, which is then rotated at high speed in order to spread the fluid by centrifugal force...
- Paper coatingCoated paperCoated paper is paper which has been coated by a compound to impart certain qualities to the paper, including weight, surface gloss, smoothness or reduced ink absorbency. Kaolinite or calcium carbonate are used to coat paper for high quality printing used in packaging industry and in magazines...
- Industrial coatingIndustrial coatingAn industrial coating is a paint or coating defined by its protective, rather than its aesthetic properties, although it can provide both.The most common use of industrial coatings is for corrosion control of steel structures such as offshore platforms, bridges and underground pipelines. Other...
Roll-to-roll coatings
Common roll-to-roll coating processes include:- Air knifeAir knifeAn air knife is a tool used to blow off liquid or debris from products as they travel on conveyors. Air knives are normally used in manufacturing or as the first step in a recursive recycling process to separate lighter or smaller particles from other components for use in later or subsequent...
coating - AniloxAniloxIn printing, anilox is a method used to provide a measured amount of ink to a flexo printing plate.An anilox roll is a hard cylinder, usually constructed of a steel or aluminum core which is coated by an industrial ceramic whose surface contains millions of very fine dimples, known as cells...
coater - Curtain CoatingCurtain CoatingCurtain coating is a process that creates an uninterrupted curtain of fluid that falls onto a substrate. The substrate is transported on a conveyor belt at a regulated speed through the curtain to ensure an even coat of the die. The curtain is created by using a slit at the base of the holding...
- Single and Multilayer Slide Coating
- Flexo coater
- Gap Coating
- Gravure coating
- Hot Melt coating
- Immersion (dip) coatingHydrographics (printing)Hydrographics or HydroGraphics, also known as immersion printing, water transfer printing, water transfer imaging or cubic printing, is a method of applying printed designs to three-dimensional objects. The hydrographic process can be used on metal, plastic, glass, hard woods, and various other...
- Knife-over-roll coating
- Metering rod (Meyer bar) coating
- Reverse Roll coating
- Roller coater
- Rotary screen
- Silk ScreenScreen-printingScreen printing is a printing technique that uses a woven mesh to support an ink-blocking stencil. The attached stencil forms open areas of mesh that transfer ink or other printable materials which can be pressed through the mesh as a sharp-edged image onto a substrate...
coater - Slot Die (ExtrusionExtrusionExtrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn through a die of the desired cross-section...
) coating
The main coating and varnishes for the printing industry include:
- Overprint varnish
- Water based coating
- Acrylic based
- Solvent based
- Aqueous coating
- UV CoatingUV Coating"UV coating" refers to surface treatments which are either cured by ultraviolet radiation, or protect the underlying material from its harmful effects.-Ultra-violet coating of paper:...
- curing (chemistry)Curing (chemistry)Curing is a term in polymer chemistry and process engineering that refers to the toughening or hardening of a polymer material by cross-linking of polymer chains, brought about by chemical additives, ultraviolet radiation, electron beam or heat...
Standards
- ISO 1461 Hot dip galvanized coatings on fabricated iron and steel articles—Specifications and test methods
- ISO 4042 Fasteners—Electroplated coatings
- ISO 10683 Fasteners—Non-electrolytically applied zinc flake coatings
- ISO 10684 Fasteners—Hot dip galvanized coatings
- ISO 12944ISO 12944ISO 12944 is an international standard for Paints and varnishes -- Corrosion protection of steel structures by protective paint systems -- Part 5: Protective paint systems.-See also:...
Paints and varnishes—Corrosion protection of steel structures by protective paint systems—Part 6: Laboratory performance test methods
See also
- Adhesion TesterAdhesion TesterIn the paint and coating industries, paint adhesion testing is necessary to determine if the paint or coating will adhere properly to the substrates to which they are applied...
- DepositionDeposition (physics)Deposition is a process in which gas transforms into solid . The reverse of deposition is sublimation.One example of deposition is the process by which, in sub-freezing air, water vapor changes directly to ice without first becoming a liquid...
- FormulationsFormulationsFormulation is a term used in various senses in various applications, both the material and the abstract or formal. Its fundamental meaning is the putting together of components in appropriate relationships or structures, according to a formula...
- Printed electronicsPrinted electronicsPrinted electronics is a set of printing methods used to create electrical devices on various substrates. Printing typically uses common printing equipment or other low-cost equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography and...
- Thermal barrier coating
- Thin-film deposition