Product Code Database
Particle board, also known as particleboard or chipboard, is an engineered wood product, belonging to the wood-based panels, manufactured from wood chips and a synthetic, mostly formaldehyde-based resin or other suitable binder, which is pressed under a hot press, batch- or continuous- type, and produced. 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.
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.
In 1932, Luftwaffe pilot and inventor Max Himmelheber patented a process for making particleboard without fully impregnating wood fibers with adhesive, distinguishing it from earlier wood composites. This particleboard could be produced with waste products such as planer shavings, off-cuts, or sawdust, Hammermill 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 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, beech, alder, pine, 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.
Resin is then sprayed as a fine mist onto the particles. Several types of resins are used in the process. Amino-formaldehyde-based resins are the best-performing based on cost and ease of use. Urea Melamine resin 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 resins can be mixed with phenolic resins, but that is more often used with marine plywood 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 Weighing 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.
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.
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 homes 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, which is banned in Canada for installation in a residential closed-cavity wall. Formaldehyde is classified by the WHO as a known human carcinogen.
|
|
