Coated paper (also known as enamel paper, gloss paper, and thin paper) is paper that has been coated by a mixture of materials or a

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

to impart certain qualities to the paper, including weight, surface gloss, smoothness, or reduced ink absorbency. Various materials, including kaolinite, calcium carbonate,

bentonite Bentonite () is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-m ...

, and

talc Talc, or talcum, is a clay mineral, composed of hydrated magnesium silicate with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent a ...

, can be used to coat paper for high-quality printing used in the packaging industry and in magazines. The

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...

china clay Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedra ...

is bound to the paper with synthetic s, such as

styrene-butadiene Styrene-butadiene or styrene-butadiene rubber (SBR) describe families of synthetic rubbers derived from styrene and butadiene (the version developed by Goodyear is called Neolite). These materials have good abrasion resistance and good aging st ...

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well. In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms ...

es and natural organic binders such as starch. The coating formulation may also contain chemical additives as

dispersant A dispersant or a dispersing agent is a substance, typically a surfactant, that is added to a suspension of solid or liquid particles in a liquid (such as a colloid or emulsion) to improve the separation of the particles and to prevent their se ...

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on n ...

s, or

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including b ...

to give water resistance and

wet strength The wet strength of paper and paperboard is a measure of how well the web of fibers holding the paper together can resist a force of rupture when the paper is wet. Wet strength is routinely expressed as the ratio of wet to dry tensile force at brea ...

to the paper, or to protect against ultraviolet radiation.

Varieties

Machine-finished coated paper

''Machine-finished coated paper'' (MFC) has a

basis weight Grammage and basis weight, in the pulp and paper industry, are the area density of a paper product, that is, its mass per unit of area. Two ways of expressing grammage are commonly used: * Expressed in grams (g) per square meter (g/m2), regardless ...

of 48–80 g/m². They have good surface properties, high print gloss and adequate sheet stiffness. MFC papers are made of 60–85% groundwood or

TMP TMP can refer to any of the following: Chemistry * 2,2,6,6-Tetramethylpiperidine, an organic chemistry reagent * Thymidine monophosphate, a nucleotide * Trimethoprim, an antibiotic * Trimethyl phosphate, a solvent * Trimethylolpropane, a precurso ...

and 15–40% chemical pulp with a total

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

content of 20–30%. The paper can be soft nip calendered or supercalendered. These are often used in

paperbacks A paperback (softcover, softback) book is one with a thick paper or paperboard cover, and often held together with glue rather than stitches or staples. In contrast, hardcover (hardback) books are bound with cardboard covered with cloth, ...

Coated fine paper

''Coated fine paper'' or ''woodfree coated paper'' (WFC) are primarily produced for offset printing: ; Standard coated fine papers: This paper quality is normally used for advertising materials, books, annual reports and high-quality catalogs. Grammage ranges from 90–170 g/m² and ISO brightness between 80–96%. The fibre furnish consists of more than 90%

chemical pulp Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw ma ...

. Total

content are in the range 30–45%, where calcium carbonate and clay are the most common. ; Low coat weight papers: These paper grades have lower coat weights than the standard WFC (3–14 g/m²/side) and the grammage and pigment content are also generally lower, 55–135 g/m² and 20–35% respectively. ; s: Art papers are one of the highest-quality printing papers and are used for illustrated books, calendars and brochures. The grammage varies from 100 to 230 g/m². These papergrades are triple coated with 20–40 g/m²/side and have matte or glossy finish. Higher qualities often contain

cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...

Plastic coatings

Plastic-coated paper Plastic-coated paper is a coated or laminated composite material made of paper or paperboard with a plastic layer or treatment on a surface. This type of coated paper is most used in the food and drink packaging industry. Function The plastic is u ...

includes types of paper coatings;

or polyolefin extrusion coating, silicone, and

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...

coating to make paper cups and photographic paper. Biopolymer coatings are available as more sustainable alternatives to common

petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable so ...

coatings like

LDPE Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. It was the first grade of polyethylene, produced in 1933 by Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. Its ...

(see

plastic-coated paper Plastic-coated paper is a coated or laminated composite material made of paper or paperboard with a plastic layer or treatment on a surface. This type of coated paper is most used in the food and drink packaging industry. Function The plastic is u ...

) or

mylar BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and a ...

Others

Printed papers commonly have a top coat of a protective polymer to seal the print, provide scuff resistance, and sometimes gloss. Some coatings are processed by

UV curing UV curing (ultraviolet curing) is the process by which ultraviolet light is used to initiate a photochemical reaction that generates a crosslinked network of polymers. UV curing is adaptable to printing, coating, decorating, stereolithography, ...

for stability. A

release liner A release liner or ''release paper'' is a paper or plastic-based film sheet (usually applied during the manufacturing process) used to prevent a sticky surface from prematurely adhering. It is coating, coated on one or both sides with a release ag ...

is a paper (or film) sheet used to prevent a sticky surface from adhering. It is coated on one or both sides with a

release agent A release agent (also mold release agent, release coating, or mold release coating) is a chemical used to prevent other materials from bonding to surfaces. It can provide a solution in processes involving mold release, die-cast release, plastic r ...

. Heat printed papers such as receipts are coated with a chemical mixture, which often contains estrogenic and carcinogenic poisons, such as BPA. It is possible to check whether a piece of paper is thermographically coated, as it will turn black from friction or heat. (see

thermal paper A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...

) Paper

label A label (as distinct from signage) is a piece of paper, plastic film, cloth, metal, or other material affixed to a container or product, on which is written or printed information or symbols about the product or item. Information printed ...

s are often coated with adhesive (pressure sensitive of gummed) on one side and coated with printing or graphics on the other.

Varieties

Machine-finished coated paper

Coated fine paper

Plastic coatings

Others

See also

References

Further reading