Paperboard
Encyclopedia
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.25 mm (0.00984251968503937 in) or 10 points) than paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
. According to ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
standards, paperboard is a paper with a basis weight (grammage) above 224 g/m2, but there are exceptions. Paperboard can be single or multi-ply. Paperboard can be easily cut and formed, is lightweight, and because it is strong, is used in packaging. Another end-use would be graphic printing, such as book and magazine covers or postcards. Sometimes it is referred to as cardboard, which is a generic, lay term used to refer to any heavy paper pulp
Pulp (paper)
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
based board.
History
In 1817, the first paperboard carton was produced in EnglandEngland
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. Folding carton
Folding carton
The folding carton created the packaging industry as it is known today, beginning in the late 19th century. Basically, a folding carton is made of paperboard, and is cut, folded, laminated and printed for transport to manufacturers. The cartons are shipped flat to a manufacturer, which has its own...
s first emerged around the 1860s and were shipped flat to save space, ready to be set up by customers when they were required. 1879 saw the development of mechanical die cutting and creasing of blanks. In 1911 the first kraft sulphate mill
Kraft process
The kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers...
was built in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
and in 1915 the gable top milk carton was patented and in 1935 the first dairy plant was observed using them. Ovenable paperboard was introduced in 1974.
Terminology and classification
Terminology and classifications of paperboard are not always uniform. Differences occur depending on specific industry, locale, and personal choice. In general, the following are often used:- Boxboard or cartonboard – paperboard for folding cartonFolding cartonThe folding carton created the packaging industry as it is known today, beginning in the late 19th century. Basically, a folding carton is made of paperboard, and is cut, folded, laminated and printed for transport to manufacturers. The cartons are shipped flat to a manufacturer, which has its own...
s and rigid set-up boxes- Folding boxboardFolding boxboardFolding boxboard also referred to as FBB, GC, UC. FBB is a paperboard grade which is made up of multiple layers of chemical and mechanical pulp. This grade is made up of mechanical pulp in between two layers of chemical pulp.The top layer is of bleached chemical pulp with an optional pigment coating...
(FBB) – a bending grade capable of being scored and bending without fracture - ChipboardChipboardChipboard may refer to:* A type of paperboard generally made from reclaimed paper stock; the term generally used in the US** White lined chipboard, a grade of paperboard* Particle board, a type of engineered wood known as "chipboard" in some countries...
– all recycled, low quality board - KraftKraft processThe kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers...
board – a strong virgin fiber board often used for beverage carriers. Often clay coated for printing - Laminated board – a lamination of paperboards and other materials, for example Liquid packaging boardLiquid packaging boardLiquid packaging board is a multi-ply paperboard with high stiffness, strong wet sizing and a high barrier coating. Only virgin paper fibers are used. The barrier coating must hold the liquid and prevent migration of air and flavors through the paperboard....
- Solid Bleached BoardSolid bleached boardSolid Bleached Board or Solid bleached sulphate is a virgin fibre grade of paperboard.This grade is made purely from bleached chemical pulp and usually has a mineral or synthetic pigment coated top surface in one or more layers as well as a coated reverse side...
(SBB) or Solid Bleached Sulphate (SBS) – clean white board used for foods etc. Sulphate refers to the Kraft processKraft processThe kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers... - Solid unbleached boardSolid unbleached boardSolid Unbleached Board also known as SUB.This is a grade of paperboard which is typically made of unbleached chemical pulp. Most often it comes with two to three layers of mineral or synthetic pigment coating on the top and one layer on the reverse side...
(SUB) – board made from unbleached chemical pulp - White lined chipboardWhite Lined ChipboardWhite Lined Chipboard, also referred to as: WLC, GD, GT or UD.This grade of paperboard is typically made from layers of waste paper or recycled fibers. Most often it comes with two to three layers of coating on the top and one layer on the reverse side...
(WLC) – a white, often clay coated, chipboard
- Folding boxboard
- ContainerboardContainerboardContainerboard, also referred to as CCM , is a type of paperboard specially manufactured for the production of corrugated board. The term encompasses both linerboard and corrugating medium , the two types of paper that make up corrugated board...
– a type of paperboard manufactured for the production of corrugated fiberboard- Corrugated medium – the inner fluted portion of corrugated fiberboard
- Linerboard – a strong stiff board for one or both sides of corrugated boxes. It is the flat covering over the corrugating medium.
- Other
- Binder's boardBinder's boardBinder's board is a paperboard used in bookbinding for making hardcovers. These are normally acid free....
– a paperboard used in bookbinding for making hardcovers.
- Binder's board
Production
Fibrous material is turned into pulpPulp (paper)
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
and bleached
Bleaching of wood pulp
Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter. The main use of wood pulp is to make paper where whiteness is an important characteristic...
, to create one or more layers of board, which can be optionally coated for a better surface and/or improved visual appearance. Paperboard are produced on paper machines that can handle higher grammages and several plies.
Raw materials
The above mentioned fibrous material can either come from fresh (virgin) sources (e.g. wood) or from recycled waste paperPaper recycling
Paper recycling is the process of recovering waste paper and remaking it into new paper products. There are three categories of paper that can be used as feedstocks for making recycled paper: mill broke, pre-consumer waste, and post-consumer waste. Mill broke is paper trimmings and other paper...
. Around 90% of virgin paper is made from wood
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
pulp.
Today paperboard packaging in general, and especially products from certified
Ecolabel
Ecolabels and Green Stickers are labelling systems for food and consumer products. Ecolabels are often voluntary, but Green Stickers are mandated by law in North America for major appliances and automobiles. They are a form of sustainability measurement directed at consumers, intended to make it...
sustainable
Sustainability
Sustainability is the capacity to endure. For humans, sustainability is the long-term maintenance of well being, which has environmental, economic, and social dimensions, and encompasses the concept of union, an interdependent relationship and mutual responsible position with all living and non...
sources, are receiving new attention, as manufacturers dealing with environmental, health, and regulatory issues look to renewable resources to meet increasing demand. It is now mandatory in many countries for paper-based packaging to be manufactured wholly or partially from recycled
Recycling
Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...
material.
Raw materials include:
- HardwoodHardwoodHardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
: Ca 0.05 inches (1.3 mm) (length) e.g. BirchBirchBirch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
which has short fibres. It is generally more difficult to work with; however, it does provide higher tensile strength, but lower tear and other strength properties. Although its fibres are not as long and strong as those in softwood, they make for a stiffer product defined by some stifness tests. Hardwood fibres fill the sheet better and therefore make a smoother paper that is more opaque and better for printing. Hardwood makes an excellent corrugating medium.
- SoftwoodSoftwoodThe term softwood is used to describe wood from trees that are known as gymnosperms.Conifers are an example. It may also be used to describe trees, which tend to be evergreen, notable exceptions being bald cypress and the larches....
: Ca 0.13 inches (3.3 mm) (length) e.g. PinePinePines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
and spruceSpruceA spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...
which have typically long fibres and make superior paperboard in services where strength is important. Softwood makes excellent linerboard.
- Recycled: Used paper is collected and sorted and usually mixed with virgin fibres in order to make new material. This is necessary as the recycled fibre often loses strength when reused; the added virgin fibres enhance strength. Mixed waste paper is not usually deinkedDeinkingDeinking is the industrial process of removing printing ink from paperfibers of recycled paper to make deinked pulp.The key in the deinking process is the ability to detach ink from the fibers. This is achieved by a combination of mechanical action and chemical means. In Europe the most common...
(skipping the deinking stage) for paperboard manufacture and hence the pulp may contain traces of inks, adhesives, and other residues which together give it a grey colour. Products made of recycled board usually have a less predictable composition and poorer functional properties than virgin fibre-based boards.
Health risks have been associated with using recycled material in direct food contact. Swiss studies have shown that recycled material can contain significant portions of mineral oil, which may migrate into packed foods. (Mineral oil levels of up to 19.4 mg/kg were found in rice packed in recycled board.)
- OthersTree-free paperTree-free paper or tree-free newsprint describes an alternative to wood-pulp paper by its raw material composition. It is claimed to be more eco-friendly considering the product's entire life cycle.Sources of fibre for tree-free paper include:...
: It is also possible to use the fibres of StrawStrawStraw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and...
, HempHempHemp is mostly used as a name for low tetrahydrocannabinol strains of the plant Cannabis sativa, of fiber and/or oilseed varieties. In modern times, hemp has been used for industrial purposes including paper, textiles, biodegradable plastics, construction, health food and fuel with modest...
, CottonCottonCotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
, FlaxFlaxFlax is a member of the genus Linum in the family Linaceae. It is native to the region extending from the eastern Mediterranean to India and was probably first domesticated in the Fertile Crescent...
, KenafKenafKenaf [Etymology: Persian], Hibiscus cannabinus, is a plant in the Malvaceae family. Hibiscus cannabinus is in the genus Hibiscus and is probably native to southern Asia, though its exact natural origin is unknown. The name also applies to the fibre obtained from this plant...
, AbacaAbacáAbacá, Musa textilis is a species of banana native to the Philippines, grown as a commercial crop in the Philippines, Ecuador, and Costa Rica. The plant is of great economic importance, being harvested for its fibre, once generally called Manila hemp, extracted from the trunk or pseudostem. On...
and other plant products
Pulping
Two principal methods for extracting fibres from their sources are:- Chemical PulpingPulp (paper)Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
uses chemical solutions to convert wood into pulp, yielding around 30% less than mechanical pulping; however, pulp made by the kraft process has superior strength
- Thermo mechanical pulp is a two stage process which results in a very high yield of wood fibres at the expense of strength.
Bleaching
Pulp used in the manufacture of paperboard can be bleachedBleaching of wood pulp
Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter. The main use of wood pulp is to make paper where whiteness is an important characteristic...
to decrease colour and increase purity. Virgin fibre pulp is naturally brown in colour, because of the presence of lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
. Recycled paperboard may contain traces of ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
s, bonding agents
Adhesive
An adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
and other residue which colors it grey.
Although bleaching
Bleaching of wood pulp
Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter. The main use of wood pulp is to make paper where whiteness is an important characteristic...
is not necessary for all end uses, it is vital for many graphical and packaging purposes. There are various methods of bleaching
Bleaching of wood pulp
Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter. The main use of wood pulp is to make paper where whiteness is an important characteristic...
, which are used according to a number of factors for example, the degree of colour change required, chemicals chosen and method of treatment. There are three categories of bleaching methods
Bleaching of wood pulp
Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter. The main use of wood pulp is to make paper where whiteness is an important characteristic...
:
- Bleaching by delignification using chlorine gas, which is a method that has been largely replaced by procedures which are gentler to the environment such as the use of oxygen as a replacement for the chlorine gas.
- Bleaching by oxidation using chemicals such as chlorine dioxideChlorine dioxideChlorine dioxide is a chemical compound with the formula ClO2. This yellowish-green gas crystallizes as bright orange crystals at −59 °C. As one of several oxides of chlorine, it is a potent and useful oxidizing agent used in water treatment and in bleaching....
, hydrogen peroxideHydrogen peroxideHydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
or sodium hypochlorite. - Bleaching by reductionRedoxRedox reactions describe all chemical reactions in which atoms have their oxidation state changed....
using chemicals such as sodium bisulphite.
Plies
Multi-ply paperboard generally has higher creasing and folding performance than single-ply as a result of layering different types of pulp into a single product. In cases where the same kind of pulp is being used in several layers, each separate layer is treated and shaped individually in order to create the highest possible quality. The benefits of multi ply paperboard are for example its higher creasing and foldingFolding
Fold or folding may refer to:* Paper folding, the art of folding paper* Book folding, in book production* Skin fold, an area of skin that folds* Fold , in the game of poker, to discard one's hand and forfeit interest in the current pot...
performance.
Coating
In order to improve whiteness, smoothness and gloss of paperboard,one or more layers of coating is applied. Coated paperCoated paper
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 ink absorbency. Kaolinite or calcium carbonate are used to coat paper for high quality printing used in packaging industry and in magazines...
is usually made up of:
- a pigmentPigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
, which could be china clay, calcium carbonateCalcium carbonateCalcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
or titanium dioxideTitanium dioxideTitanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
, usually a combination of two - an adhesive or binder as styrene-butadieneStyrene-butadieneStyrene-Butadiene or Styrene-Butadiene-Rubber is a synthetic rubber copolymer consisting of styrene and butadiene. It has good abrasion resistance and good aging stability when protected by additives, and is widely used in car tires, where it may be blended with natural rubber...
emulsions or starchStarchStarch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
es and waterWaterWater is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
.
Additional components could be OBA (optical brightening agent
Optical brightener
Optical brighteners, optical brightening agents , fluorescent brightening agents or fluorescent whitening agents are dyes that absorb light in the ultraviolet and violet region of the electromagnetic spectrum, and re-emit light in the blue region...
s).
Grades
The DINDeutsches Institut für Normung
is the German national organization for standardization and is that country's ISO member body. DIN is a Registered German Association headquartered in Berlin...
Standard 19303 "Paperboard - Terms and grades" (Publication date : 2005-09) defines different grades of paperboard based on the surface treatment (first letter), the main furnish (second letter) and the colour (non-D grade) or bulk (D grade only) (numbering).
| First letter (surface treatment) |
Second letter (main furnish) |
Number |
|---|---|---|
| A = cast-coated G = pigment coated U = uncoated |
Z = bleached virgin chemical pulp C = virgin mechanical pulp N = unbleached virgin chemical pulp T = recycled/secondary fibre with white, cream or brown reverse D = recycled/secondary fibre with grey back |
(all except D grades): 1 = white reverse side 2 = cream reverse side 3 = brown reverse side (D grades only): 1 = bulk >= 1.45 cm³/g 2 = bulk < 1.45 cm³/g, > 1.3 cm³/g 3 = bulk <= 1.3 cm³/g |
Example: GC1 would be a "pigment coated", "virgin mechanical pulp" board with a "white reverse side". Often the used paperboard type would be FBB, which was coated on both sides.
Common terms
Basis Weight (US): Is the weight 1000 square feet (92.9 m²) of paperboard.Brightness: Brightness is a technical term that is defined as the amount of blue-white light that a paper reflects. This property is very subjective and individual to each buyer and end use, as skin colour and food are better reproduced on ‘warm’ (yellow) whites and not blue whites.
Grammage: The grammage of the paperboard is assessed in accordance ISO 536.
Grammage expresses weight per unit area and is measured in g/m2.
PH: Surface pH is measured on a water extract and is on a scale of 0-14, 0 being acidic, 7 neutral and 14 alkaline.
Stiffness: Stiffness is one of the most important properties of paperboard as it affects the ability of cartons to run smoothly through the machine that erects, fills and closes them. Stiffness also gives strength and reduces the propensity of a carton to bulge under the weight of settling flowable contents such as cereals.
Although most paper strength properties increase with increasing sheet density, stifness does not. A rule of thumb is that stiffness is proportional to the 1.6 power of sheet caliper.
The species fo fiber used has an effect on stiffness, other things being equal. Northern softwood species impart superior stiffness sompared to southern softwoods.
Other factors which affect board stiffness include coatings and moisture content.
Smoothness: Smoothness is particularly important when being used for printing, the smoother the paperboard, the better the image quality, because of better ink coverage. Smoothness is measured using air leak methods – the greater the rate of air leakage, at a specific air pressure, from under a cylindrical knife placed on the surface, the rougher the surface.
Caliper/Thickness: In the US caliper is usually expressed in thousandths of an inch (0.001”) or points, where a sheet of paperboard with a thickness of 0.024” would be 24 points. In Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
it is measured in g/m2. Paperboard also tends to be referred to with thickness rather than weight.
Whiteness: It refers ideally to the equal presence of all colours, because a truly white sheet will reflect all wavelengths of visible light equally.
Paperboard industry
The paperboard sector is mainly looked at in conjunction with the paper industry. The Paper & Paperboard market size (2007) had a value of 630.9 billion USD and a volume of 320.3 million metric tons . 40.1% of that market is European. About 50% of all produced paper is used for packaging, followed by printing and writing. The consumption of paper and paperboard seem to correlate with economic trends (GDP)According to ProCarton, the consumption of paper and paperboard seem to correlate with economic trends (GDP) the sales of carton in Europe sum up to around 8 billion Euros worth. Over 1,100 printers consume 5.4 million tonnes of cartonboard yearly. Cartons make up one third of paper and board packaging and 15% of all packaging. A bit more than half (54%) of the European carton is produced using recovered fibre or waste paper.
The paper and paperboard industry is quite energy and capital intensive. Just a coated board machine itself can costs around 90 - 120 million Euros
(about 125 - 166 million USD in 11/2011). Economies of scale apply, because of which a few large players often dominate the market place. E.g. in North America the top 5 producers have a market share of 85%.
Further reading
- Brody, A. L., and Marsh, K, S., "Encyclopedia of Packaging Technology", John Wiley & Sons, 1997, ISBN 0-471-06397-5
- Soroka, W, "Fundamentals of Packaging Technology", IoPP, 2002, ISBN 1-930268-25-4
External links
- TAPPI Technical Association of the Pulp and Paper Industry
- Paperboard Packaging A renewable, recyclable resource for innovation (Videos)