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Particle board, also known as chipboard or low-density fiberboard, is an engineered wood product manufactured from wood chips and a synthetic
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 nat ...
or other suitable binder, which is pressed and extruded. Particle board is often confused with oriented strand board (OSB) (also known as flakeboard, or waferboard), a different type of fiberboard that uses machined wood flakes and offers more strength.


Characteristics

Particle board is cheaper,
denser Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematically ...
and more uniform than conventional wood and
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
and is substituted for them when cost is more important than strength and appearance. Particleboard can be made more appealing by painting or the use of wood veneers on visible surfaces. Though it is denser than conventional wood, it is the lightest and weakest type of fiberboard, except for insulation board. Medium-density fibreboard and hardboard, also called high-density fiberboard, are stronger and denser than particleboard. Different grades of particleboard have different densities, with higher density connoting greater strength and greater resistance to failure of screw fasteners. A significant disadvantage of particleboard is its susceptibility to expansion and discoloration from moisture absorption, particularly when it is not covered with paint or another sealer. Therefore, it is rarely used outdoors or in places where there are high levels of moisture, except in bathrooms, kitchens and laundries, where it is commonly used as an underlayment shielded beneath a moisture resistant continuous sheet of vinyl flooring. In dry environments, veneered particleboard is preferred over veneered plywood because of its stability, lower cost, and convenience.


History and development

Particleboard originated in Germany. It was first produced in 1887, when Hubbard made so-called "artificial wood" from wood flour and an adhesive based on
albumin Albumin is a family of globular proteins, the most common of which are the serum albumins. All the proteins of the albumin family are water- soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Album ...
, which was consolidated under high temperature and pressure. During the
Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...
, phenolic resin was more readily accessible than top-grade wood veneer in Germany, and
Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German '' Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the '' Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabt ...
pilot and inventor Max Himmelheber played a role in making the first sheets of particleboard, which were little more than pourings of floor sweepings, wood chips, and ground-up off-cuts and glue. The first commercial piece was produced during the Second World War at a factory in Bremen, Germany. For its production, waste material was used, such as planer shavings, off-cuts or sawdust, hammer-milled into chips and bound together with a phenolic resin. Hammer-milling involves smashing material into smaller and smaller pieces until they can pass through a screen. Most other early particleboard manufacturers used similar processes, though often with slightly different resins. It was found that better strength, appearance and resin economy could be achieved by using more uniform, manufactured chips. Producers began processing solid
birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' cont ...
,
beech Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engl ...
, alder,
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...
and spruce into consistent chips and flakes; these finer layers were then placed on the outside of the board, with its core composed of coarser, cheaper chips. This type of board is known as three-layer particleboard. More recently, graded-density particleboard has also evolved. It contains particles that gradually become smaller as they get closer to the surface.


Manufacturing

Particleboard or chipboard is manufactured by mixing particles or flakes of wood or jute-stick together with a
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 nat ...
and forming the mixture into a sheet. The raw material is fed into a disc chipper with between four and sixteen radially arranged blades. The chips from disk chippers are more uniform in shape and size than from other types of wood chippers. The particles are then dried, and any oversize or undersized particles are screened out.
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 nat ...
is then sprayed as a fine mist onto the particles. Several types of resins are used in the procces. Amino-formaldehyde based resins are the best performing based on cost and ease of use. Urea melamine resins offer water resistance with more melamine offering higher resistance. It is typically used in external applications, with the coloured resin darkening the panel. To further enhance the panel properties,
resorcinol Resorcinol (or resorcin) is an organic compound with the formula C6H4(OH)2. It is one of three isomeric benzenediols, the 1,3-isomer (or '' meta''-isomer). Resorcinol crystallizes from benzene as colorless needles that are readily soluble in ...
resins can be mixed with phenolic resins, but that is more often used with
marine plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
applications. Panel production involves other chemicals including wax, dyes, wetting agents and release agents, to aid processing or make the final product resistant to water, fire or insects. After the particles pass through a mist of resin sufficient to coat all surfaces, they are layered into a continuous carpet. This 'carpet' is then separated into discrete, rectangular 'blankets' which will be compacted in a cold press. A scale weighs the flakes, and they are distributed by rotating rakes. In graded-density particleboard, the flakes are spread by an air jet that throws finer particles further than coarse ones. Two such jets, reversed, allow the particles to build up from fine to coarse and back to fine. The formed sheets are cold-compressed to reduce thickness and make them easier to transport. Later, they are compressed again, under pressures between and temperatures between to set and harden the glue. The entire process is controlled to ensure the correct size, density and consistency of the board. The boards are then cooled, trimmed and sanded. They can then be sold as raw board or surface improved through the addition of a wood veneer or laminate surface.


Furniture design

Particle board has had a huge influence on furniture design. In the early 1950s, particle board kitchens started to come into use in furniture construction but, in many cases, it remained more expensive than solid wood. A particle board kitchen was only available to the very wealthy. Once the technology was more developed, particle board became cheaper. Some large companies base their strategies around providing furniture at a low price. To do this, they use the least expensive materials possible. In almost all cases, this means particle board, medium-density fibreboard (MDF), or the like. However, in order to maintain a reputation for quality at low cost, manufacturers may use higher grades of particle board, e.g., higher density particle board, thicker particle board, or particle board using higher-quality resins. One may note the amount of sag in a shelf of a given width in order to draw the distinction. In general, the much lower cost of sheet goods (particle board, medium density fiberboard, and other engineered wood products) has helped to displace solid wood from many cabinetry applications.


Safety

Safety concerns exist for both manufacturing and use. Fine dust and chemicals are released when particleboard is machined (e.g., sawing or routing). Occupational exposure limits exist in many countries recognizing the hazard of wood dusts. Cutting particle board can release
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
,
carbon monoxide Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ...
,
hydrogen cyanide Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on a ...
in the case of amino resins, and
phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it r ...
in the case of phenol formaldehyde resins. The other safety concern is the slow release of formaldehyde over time. In 1984 concerns about the high indoor levels of formaldehyde in new
manufactured home Manufactured housing (commonly known as mobile homes in the United States) is a type of prefabricated housing that is largely assembled in factories and then transported to sites of use. The definition of the term in the United States is regul ...
s led the United States Department of Housing and Urban Development to set construction standards. Particleboard (PB), medium-density fibreboard (MDF), oriented strand board (OSB), and laminated flooring have been major sources of formaldehyde emissions. In response to consumer and woodworker pressure on the industry, PB and MDF became available in "no added formaldehyde" (NAF) versions, but were not in common use . Many other building materials such as furniture finish, carpeting and caulking give off formaldehyde, as well as
urea-formaldehyde foam insulation Urea-formaldehyde (UF), also known as urea-methanal, so named for its common synthesis pathway and overall structure, is a nontransparent thermosetting resin or polymer. It is produced from urea and formaldehyde. These resins are used in adhesive ...
, which is banned in Canada for installation in a residential closed cavity wall. Formaldehyde is classified by the WHO as a known human
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
.


See also

* Fiberboard *
Glued laminated timber Glued laminated timber, commonly referred to as glulam, is a type of structural engineered wood product constituted by layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives so that all of the grain r ...
* Masonite * Pressed wood *
Waferboard Waferboard belongs to the subset of reconstituted wood panel products called flakeboards. It is a structural material made from rectangular wood flakes of controlled length and thickness bonded together with waterproof phenolic resin under extrem ...
* Haskelite


References


External links


Composite Panel Association: Particleboard

European Panel Federation: Particleboard
{{DEFAULTSORT:Particle Board Composite materials Woodworking materials Engineered wood German inventions of the Nazi period es:Madera#Aglomerados o conglomerados